Merge tag 'sched-urgent-2024-03-24' of git://git.kernel.org/pub/scm/linux/kernel...

[sfrench/cifs-2.6.git] / kernel / trace / ftrace.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Infrastructure for profiling code inserted by 'gcc -pg'.
 *
 * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
 * Copyright (C) 2004-2008 Ingo Molnar <mingo@redhat.com>
 *
 * Originally ported from the -rt patch by:
 *   Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
 *
 * Based on code in the latency_tracer, that is:
 *
 *  Copyright (C) 2004-2006 Ingo Molnar
 *  Copyright (C) 2004 Nadia Yvette Chambers
 */

#include <linux/stop_machine.h>
#include <linux/clocksource.h>
#include <linux/sched/task.h>
#include <linux/kallsyms.h>
#include <linux/security.h>
#include <linux/seq_file.h>
#include <linux/tracefs.h>
#include <linux/hardirq.h>
#include <linux/kthread.h>
#include <linux/uaccess.h>
#include <linux/bsearch.h>
#include <linux/module.h>
#include <linux/ftrace.h>
#include <linux/sysctl.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include <linux/sort.h>
#include <linux/list.h>
#include <linux/hash.h>
#include <linux/rcupdate.h>
#include <linux/kprobes.h>

#include <trace/events/sched.h>

#include <asm/sections.h>
#include <asm/setup.h>

#include "ftrace_internal.h"
#include "trace_output.h"
#include "trace_stat.h"

/* Flags that do not get reset */
#define FTRACE_NOCLEAR_FLAGS    (FTRACE_FL_DISABLED | FTRACE_FL_TOUCHED | \
                                 FTRACE_FL_MODIFIED)

#define FTRACE_INVALID_FUNCTION         "__ftrace_invalid_address__"

#define FTRACE_WARN_ON(cond)                    \
        ({                                      \
                int ___r = cond;                \
                if (WARN_ON(___r))              \
                        ftrace_kill();          \
                ___r;                           \
        })

#define FTRACE_WARN_ON_ONCE(cond)               \
        ({                                      \
                int ___r = cond;                \
                if (WARN_ON_ONCE(___r))         \
                        ftrace_kill();          \
                ___r;                           \
        })

/* hash bits for specific function selection */
#define FTRACE_HASH_DEFAULT_BITS 10
#define FTRACE_HASH_MAX_BITS 12

#ifdef CONFIG_DYNAMIC_FTRACE
#define INIT_OPS_HASH(opsname)  \
        .func_hash              = &opsname.local_hash,                  \
        .local_hash.regex_lock  = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock),
#else
#define INIT_OPS_HASH(opsname)
#endif

enum {
        FTRACE_MODIFY_ENABLE_FL         = (1 << 0),
        FTRACE_MODIFY_MAY_SLEEP_FL      = (1 << 1),
};

struct ftrace_ops ftrace_list_end __read_mostly = {
        .func           = ftrace_stub,
        .flags          = FTRACE_OPS_FL_STUB,
        INIT_OPS_HASH(ftrace_list_end)
};

/* ftrace_enabled is a method to turn ftrace on or off */
int ftrace_enabled __read_mostly;
static int __maybe_unused last_ftrace_enabled;

/* Current function tracing op */
struct ftrace_ops *function_trace_op __read_mostly = &ftrace_list_end;
/* What to set function_trace_op to */
static struct ftrace_ops *set_function_trace_op;

static bool ftrace_pids_enabled(struct ftrace_ops *ops)
{
        struct trace_array *tr;

        if (!(ops->flags & FTRACE_OPS_FL_PID) || !ops->private)
                return false;

        tr = ops->private;

        return tr->function_pids != NULL || tr->function_no_pids != NULL;
}

static void ftrace_update_trampoline(struct ftrace_ops *ops);

/*
 * ftrace_disabled is set when an anomaly is discovered.
 * ftrace_disabled is much stronger than ftrace_enabled.
 */
static int ftrace_disabled __read_mostly;

DEFINE_MUTEX(ftrace_lock);

struct ftrace_ops __rcu *ftrace_ops_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
struct ftrace_ops global_ops;

/* Defined by vmlinux.lds.h see the comment above arch_ftrace_ops_list_func for details */
void ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
                          struct ftrace_ops *op, struct ftrace_regs *fregs);

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS
/*
 * Stub used to invoke the list ops without requiring a separate trampoline.
 */
const struct ftrace_ops ftrace_list_ops = {
        .func   = ftrace_ops_list_func,
        .flags  = FTRACE_OPS_FL_STUB,
};

static void ftrace_ops_nop_func(unsigned long ip, unsigned long parent_ip,
                                struct ftrace_ops *op,
                                struct ftrace_regs *fregs)
{
        /* do nothing */
}

/*
 * Stub used when a call site is disabled. May be called transiently by threads
 * which have made it into ftrace_caller but haven't yet recovered the ops at
 * the point the call site is disabled.
 */
const struct ftrace_ops ftrace_nop_ops = {
        .func   = ftrace_ops_nop_func,
        .flags  = FTRACE_OPS_FL_STUB,
};
#endif

static inline void ftrace_ops_init(struct ftrace_ops *ops)
{
#ifdef CONFIG_DYNAMIC_FTRACE
        if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED)) {
                mutex_init(&ops->local_hash.regex_lock);
                ops->func_hash = &ops->local_hash;
                ops->flags |= FTRACE_OPS_FL_INITIALIZED;
        }
#endif
}

static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
                            struct ftrace_ops *op, struct ftrace_regs *fregs)
{
        struct trace_array *tr = op->private;
        int pid;

        if (tr) {
                pid = this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid);
                if (pid == FTRACE_PID_IGNORE)
                        return;
                if (pid != FTRACE_PID_TRACE &&
                    pid != current->pid)
                        return;
        }

        op->saved_func(ip, parent_ip, op, fregs);
}

static void ftrace_sync_ipi(void *data)
{
        /* Probably not needed, but do it anyway */
        smp_rmb();
}

static ftrace_func_t ftrace_ops_get_list_func(struct ftrace_ops *ops)
{
        /*
         * If this is a dynamic or RCU ops, or we force list func,
         * then it needs to call the list anyway.
         */
        if (ops->flags & (FTRACE_OPS_FL_DYNAMIC | FTRACE_OPS_FL_RCU) ||
            FTRACE_FORCE_LIST_FUNC)
                return ftrace_ops_list_func;

        return ftrace_ops_get_func(ops);
}

static void update_ftrace_function(void)
{
        ftrace_func_t func;

        /*
         * Prepare the ftrace_ops that the arch callback will use.
         * If there's only one ftrace_ops registered, the ftrace_ops_list
         * will point to the ops we want.
         */
        set_function_trace_op = rcu_dereference_protected(ftrace_ops_list,
                                                lockdep_is_held(&ftrace_lock));

        /* If there's no ftrace_ops registered, just call the stub function */
        if (set_function_trace_op == &ftrace_list_end) {
                func = ftrace_stub;

        /*
         * If we are at the end of the list and this ops is
         * recursion safe and not dynamic and the arch supports passing ops,
         * then have the mcount trampoline call the function directly.
         */
        } else if (rcu_dereference_protected(ftrace_ops_list->next,
                        lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
                func = ftrace_ops_get_list_func(ftrace_ops_list);

        } else {
                /* Just use the default ftrace_ops */
                set_function_trace_op = &ftrace_list_end;
                func = ftrace_ops_list_func;
        }

        update_function_graph_func();

        /* If there's no change, then do nothing more here */
        if (ftrace_trace_function == func)
                return;

        /*
         * If we are using the list function, it doesn't care
         * about the function_trace_ops.
         */
        if (func == ftrace_ops_list_func) {
                ftrace_trace_function = func;
                /*
                 * Don't even bother setting function_trace_ops,
                 * it would be racy to do so anyway.
                 */
                return;
        }

#ifndef CONFIG_DYNAMIC_FTRACE
        /*
         * For static tracing, we need to be a bit more careful.
         * The function change takes affect immediately. Thus,
         * we need to coordinate the setting of the function_trace_ops
         * with the setting of the ftrace_trace_function.
         *
         * Set the function to the list ops, which will call the
         * function we want, albeit indirectly, but it handles the
         * ftrace_ops and doesn't depend on function_trace_op.
         */
        ftrace_trace_function = ftrace_ops_list_func;
        /*
         * Make sure all CPUs see this. Yes this is slow, but static
         * tracing is slow and nasty to have enabled.
         */
        synchronize_rcu_tasks_rude();
        /* Now all cpus are using the list ops. */
        function_trace_op = set_function_trace_op;
        /* Make sure the function_trace_op is visible on all CPUs */
        smp_wmb();
        /* Nasty way to force a rmb on all cpus */
        smp_call_function(ftrace_sync_ipi, NULL, 1);
        /* OK, we are all set to update the ftrace_trace_function now! */
#endif /* !CONFIG_DYNAMIC_FTRACE */

        ftrace_trace_function = func;
}

static void add_ftrace_ops(struct ftrace_ops __rcu **list,
                           struct ftrace_ops *ops)
{
        rcu_assign_pointer(ops->next, *list);

        /*
         * We are entering ops into the list but another
         * CPU might be walking that list. We need to make sure
         * the ops->next pointer is valid before another CPU sees
         * the ops pointer included into the list.
         */
        rcu_assign_pointer(*list, ops);
}

static int remove_ftrace_ops(struct ftrace_ops __rcu **list,
                             struct ftrace_ops *ops)
{
        struct ftrace_ops **p;

        /*
         * If we are removing the last function, then simply point
         * to the ftrace_stub.
         */
        if (rcu_dereference_protected(*list,
                        lockdep_is_held(&ftrace_lock)) == ops &&
            rcu_dereference_protected(ops->next,
                        lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
                *list = &ftrace_list_end;
                return 0;
        }

        for (p = list; *p != &ftrace_list_end; p = &(*p)->next)
                if (*p == ops)
                        break;

        if (*p != ops)
                return -1;

        *p = (*p)->next;
        return 0;
}

static void ftrace_update_trampoline(struct ftrace_ops *ops);

int __register_ftrace_function(struct ftrace_ops *ops)
{
        if (ops->flags & FTRACE_OPS_FL_DELETED)
                return -EINVAL;

        if (WARN_ON(ops->flags & FTRACE_OPS_FL_ENABLED))
                return -EBUSY;

#ifndef CONFIG_DYNAMIC_FTRACE_WITH_REGS
        /*
         * If the ftrace_ops specifies SAVE_REGS, then it only can be used
         * if the arch supports it, or SAVE_REGS_IF_SUPPORTED is also set.
         * Setting SAVE_REGS_IF_SUPPORTED makes SAVE_REGS irrelevant.
         */
        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS &&
            !(ops->flags & FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED))
                return -EINVAL;

        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED)
                ops->flags |= FTRACE_OPS_FL_SAVE_REGS;
#endif
        if (!ftrace_enabled && (ops->flags & FTRACE_OPS_FL_PERMANENT))
                return -EBUSY;

        if (!is_kernel_core_data((unsigned long)ops))
                ops->flags |= FTRACE_OPS_FL_DYNAMIC;

        add_ftrace_ops(&ftrace_ops_list, ops);

        /* Always save the function, and reset at unregistering */
        ops->saved_func = ops->func;

        if (ftrace_pids_enabled(ops))
                ops->func = ftrace_pid_func;

        ftrace_update_trampoline(ops);

        if (ftrace_enabled)
                update_ftrace_function();

        return 0;
}

int __unregister_ftrace_function(struct ftrace_ops *ops)
{
        int ret;

        if (WARN_ON(!(ops->flags & FTRACE_OPS_FL_ENABLED)))
                return -EBUSY;

        ret = remove_ftrace_ops(&ftrace_ops_list, ops);

        if (ret < 0)
                return ret;

        if (ftrace_enabled)
                update_ftrace_function();

        ops->func = ops->saved_func;

        return 0;
}

static void ftrace_update_pid_func(void)
{
        struct ftrace_ops *op;

        /* Only do something if we are tracing something */
        if (ftrace_trace_function == ftrace_stub)
                return;

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                if (op->flags & FTRACE_OPS_FL_PID) {
                        op->func = ftrace_pids_enabled(op) ?
                                ftrace_pid_func : op->saved_func;
                        ftrace_update_trampoline(op);
                }
        } while_for_each_ftrace_op(op);

        update_ftrace_function();
}

#ifdef CONFIG_FUNCTION_PROFILER
struct ftrace_profile {
        struct hlist_node               node;
        unsigned long                   ip;
        unsigned long                   counter;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        unsigned long long              time;
        unsigned long long              time_squared;
#endif
};

struct ftrace_profile_page {
        struct ftrace_profile_page      *next;
        unsigned long                   index;
        struct ftrace_profile           records[];
};

struct ftrace_profile_stat {
        atomic_t                        disabled;
        struct hlist_head               *hash;
        struct ftrace_profile_page      *pages;
        struct ftrace_profile_page      *start;
        struct tracer_stat              stat;
};

#define PROFILE_RECORDS_SIZE                                            \
        (PAGE_SIZE - offsetof(struct ftrace_profile_page, records))

#define PROFILES_PER_PAGE                                       \
        (PROFILE_RECORDS_SIZE / sizeof(struct ftrace_profile))

static int ftrace_profile_enabled __read_mostly;

/* ftrace_profile_lock - synchronize the enable and disable of the profiler */
static DEFINE_MUTEX(ftrace_profile_lock);

static DEFINE_PER_CPU(struct ftrace_profile_stat, ftrace_profile_stats);

#define FTRACE_PROFILE_HASH_BITS 10
#define FTRACE_PROFILE_HASH_SIZE (1 << FTRACE_PROFILE_HASH_BITS)

static void *
function_stat_next(void *v, int idx)
{
        struct ftrace_profile *rec = v;
        struct ftrace_profile_page *pg;

        pg = (struct ftrace_profile_page *)((unsigned long)rec & PAGE_MASK);

 again:
        if (idx != 0)
                rec++;

        if ((void *)rec >= (void *)&pg->records[pg->index]) {
                pg = pg->next;
                if (!pg)
                        return NULL;
                rec = &pg->records[0];
                if (!rec->counter)
                        goto again;
        }

        return rec;
}

static void *function_stat_start(struct tracer_stat *trace)
{
        struct ftrace_profile_stat *stat =
                container_of(trace, struct ftrace_profile_stat, stat);

        if (!stat || !stat->start)
                return NULL;

        return function_stat_next(&stat->start->records[0], 0);
}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/* function graph compares on total time */
static int function_stat_cmp(const void *p1, const void *p2)
{
        const struct ftrace_profile *a = p1;
        const struct ftrace_profile *b = p2;

        if (a->time < b->time)
                return -1;
        if (a->time > b->time)
                return 1;
        else
                return 0;
}
#else
/* not function graph compares against hits */
static int function_stat_cmp(const void *p1, const void *p2)
{
        const struct ftrace_profile *a = p1;
        const struct ftrace_profile *b = p2;

        if (a->counter < b->counter)
                return -1;
        if (a->counter > b->counter)
                return 1;
        else
                return 0;
}
#endif

static int function_stat_headers(struct seq_file *m)
{
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        seq_puts(m, "  Function                               "
                 "Hit    Time            Avg             s^2\n"
                    "  --------                               "
                 "---    ----            ---             ---\n");
#else
        seq_puts(m, "  Function                               Hit\n"
                    "  --------                               ---\n");
#endif
        return 0;
}

static int function_stat_show(struct seq_file *m, void *v)
{
        struct ftrace_profile *rec = v;
        char str[KSYM_SYMBOL_LEN];
        int ret = 0;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        static struct trace_seq s;
        unsigned long long avg;
        unsigned long long stddev;
#endif
        mutex_lock(&ftrace_profile_lock);

        /* we raced with function_profile_reset() */
        if (unlikely(rec->counter == 0)) {
                ret = -EBUSY;
                goto out;
        }

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        avg = div64_ul(rec->time, rec->counter);
        if (tracing_thresh && (avg < tracing_thresh))
                goto out;
#endif

        kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
        seq_printf(m, "  %-30.30s  %10lu", str, rec->counter);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        seq_puts(m, "    ");

        /* Sample standard deviation (s^2) */
        if (rec->counter <= 1)
                stddev = 0;
        else {
                /*
                 * Apply Welford's method:
                 * s^2 = 1 / (n * (n-1)) * (n * \Sum (x_i)^2 - (\Sum x_i)^2)
                 */
                stddev = rec->counter * rec->time_squared -
                         rec->time * rec->time;

                /*
                 * Divide only 1000 for ns^2 -> us^2 conversion.
                 * trace_print_graph_duration will divide 1000 again.
                 */
                stddev = div64_ul(stddev,
                                  rec->counter * (rec->counter - 1) * 1000);
        }

        trace_seq_init(&s);
        trace_print_graph_duration(rec->time, &s);
        trace_seq_puts(&s, "    ");
        trace_print_graph_duration(avg, &s);
        trace_seq_puts(&s, "    ");
        trace_print_graph_duration(stddev, &s);
        trace_print_seq(m, &s);
#endif
        seq_putc(m, '\n');
out:
        mutex_unlock(&ftrace_profile_lock);

        return ret;
}

static void ftrace_profile_reset(struct ftrace_profile_stat *stat)
{
        struct ftrace_profile_page *pg;

        pg = stat->pages = stat->start;

        while (pg) {
                memset(pg->records, 0, PROFILE_RECORDS_SIZE);
                pg->index = 0;
                pg = pg->next;
        }

        memset(stat->hash, 0,
               FTRACE_PROFILE_HASH_SIZE * sizeof(struct hlist_head));
}

static int ftrace_profile_pages_init(struct ftrace_profile_stat *stat)
{
        struct ftrace_profile_page *pg;
        int functions;
        int pages;
        int i;

        /* If we already allocated, do nothing */
        if (stat->pages)
                return 0;

        stat->pages = (void *)get_zeroed_page(GFP_KERNEL);
        if (!stat->pages)
                return -ENOMEM;

#ifdef CONFIG_DYNAMIC_FTRACE
        functions = ftrace_update_tot_cnt;
#else
        /*
         * We do not know the number of functions that exist because
         * dynamic tracing is what counts them. With past experience
         * we have around 20K functions. That should be more than enough.
         * It is highly unlikely we will execute every function in
         * the kernel.
         */
        functions = 20000;
#endif

        pg = stat->start = stat->pages;

        pages = DIV_ROUND_UP(functions, PROFILES_PER_PAGE);

        for (i = 1; i < pages; i++) {
                pg->next = (void *)get_zeroed_page(GFP_KERNEL);
                if (!pg->next)
                        goto out_free;
                pg = pg->next;
        }

        return 0;

 out_free:
        pg = stat->start;
        while (pg) {
                unsigned long tmp = (unsigned long)pg;

                pg = pg->next;
                free_page(tmp);
        }

        stat->pages = NULL;
        stat->start = NULL;

        return -ENOMEM;
}

static int ftrace_profile_init_cpu(int cpu)
{
        struct ftrace_profile_stat *stat;
        int size;

        stat = &per_cpu(ftrace_profile_stats, cpu);

        if (stat->hash) {
                /* If the profile is already created, simply reset it */
                ftrace_profile_reset(stat);
                return 0;
        }

        /*
         * We are profiling all functions, but usually only a few thousand
         * functions are hit. We'll make a hash of 1024 items.
         */
        size = FTRACE_PROFILE_HASH_SIZE;

        stat->hash = kcalloc(size, sizeof(struct hlist_head), GFP_KERNEL);

        if (!stat->hash)
                return -ENOMEM;

        /* Preallocate the function profiling pages */
        if (ftrace_profile_pages_init(stat) < 0) {
                kfree(stat->hash);
                stat->hash = NULL;
                return -ENOMEM;
        }

        return 0;
}

static int ftrace_profile_init(void)
{
        int cpu;
        int ret = 0;

        for_each_possible_cpu(cpu) {
                ret = ftrace_profile_init_cpu(cpu);
                if (ret)
                        break;
        }

        return ret;
}

/* interrupts must be disabled */
static struct ftrace_profile *
ftrace_find_profiled_func(struct ftrace_profile_stat *stat, unsigned long ip)
{
        struct ftrace_profile *rec;
        struct hlist_head *hhd;
        unsigned long key;

        key = hash_long(ip, FTRACE_PROFILE_HASH_BITS);
        hhd = &stat->hash[key];

        if (hlist_empty(hhd))
                return NULL;

        hlist_for_each_entry_rcu_notrace(rec, hhd, node) {
                if (rec->ip == ip)
                        return rec;
        }

        return NULL;
}

static void ftrace_add_profile(struct ftrace_profile_stat *stat,
                               struct ftrace_profile *rec)
{
        unsigned long key;

        key = hash_long(rec->ip, FTRACE_PROFILE_HASH_BITS);
        hlist_add_head_rcu(&rec->node, &stat->hash[key]);
}

/*
 * The memory is already allocated, this simply finds a new record to use.
 */
static struct ftrace_profile *
ftrace_profile_alloc(struct ftrace_profile_stat *stat, unsigned long ip)
{
        struct ftrace_profile *rec = NULL;

        /* prevent recursion (from NMIs) */
        if (atomic_inc_return(&stat->disabled) != 1)
                goto out;

        /*
         * Try to find the function again since an NMI
         * could have added it
         */
        rec = ftrace_find_profiled_func(stat, ip);
        if (rec)
                goto out;

        if (stat->pages->index == PROFILES_PER_PAGE) {
                if (!stat->pages->next)
                        goto out;
                stat->pages = stat->pages->next;
        }

        rec = &stat->pages->records[stat->pages->index++];
        rec->ip = ip;
        ftrace_add_profile(stat, rec);

 out:
        atomic_dec(&stat->disabled);

        return rec;
}

static void
function_profile_call(unsigned long ip, unsigned long parent_ip,
                      struct ftrace_ops *ops, struct ftrace_regs *fregs)
{
        struct ftrace_profile_stat *stat;
        struct ftrace_profile *rec;
        unsigned long flags;

        if (!ftrace_profile_enabled)
                return;

        local_irq_save(flags);

        stat = this_cpu_ptr(&ftrace_profile_stats);
        if (!stat->hash || !ftrace_profile_enabled)
                goto out;

        rec = ftrace_find_profiled_func(stat, ip);
        if (!rec) {
                rec = ftrace_profile_alloc(stat, ip);
                if (!rec)
                        goto out;
        }

        rec->counter++;
 out:
        local_irq_restore(flags);
}

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static bool fgraph_graph_time = true;

void ftrace_graph_graph_time_control(bool enable)
{
        fgraph_graph_time = enable;
}

static int profile_graph_entry(struct ftrace_graph_ent *trace)
{
        struct ftrace_ret_stack *ret_stack;

        function_profile_call(trace->func, 0, NULL, NULL);

        /* If function graph is shutting down, ret_stack can be NULL */
        if (!current->ret_stack)
                return 0;

        ret_stack = ftrace_graph_get_ret_stack(current, 0);
        if (ret_stack)
                ret_stack->subtime = 0;

        return 1;
}

static void profile_graph_return(struct ftrace_graph_ret *trace)
{
        struct ftrace_ret_stack *ret_stack;
        struct ftrace_profile_stat *stat;
        unsigned long long calltime;
        struct ftrace_profile *rec;
        unsigned long flags;

        local_irq_save(flags);
        stat = this_cpu_ptr(&ftrace_profile_stats);
        if (!stat->hash || !ftrace_profile_enabled)
                goto out;

        /* If the calltime was zero'd ignore it */
        if (!trace->calltime)
                goto out;

        calltime = trace->rettime - trace->calltime;

        if (!fgraph_graph_time) {

                /* Append this call time to the parent time to subtract */
                ret_stack = ftrace_graph_get_ret_stack(current, 1);
                if (ret_stack)
                        ret_stack->subtime += calltime;

                ret_stack = ftrace_graph_get_ret_stack(current, 0);
                if (ret_stack && ret_stack->subtime < calltime)
                        calltime -= ret_stack->subtime;
                else
                        calltime = 0;
        }

        rec = ftrace_find_profiled_func(stat, trace->func);
        if (rec) {
                rec->time += calltime;
                rec->time_squared += calltime * calltime;
        }

 out:
        local_irq_restore(flags);
}

static struct fgraph_ops fprofiler_ops = {
        .entryfunc = &profile_graph_entry,
        .retfunc = &profile_graph_return,
};

static int register_ftrace_profiler(void)
{
        return register_ftrace_graph(&fprofiler_ops);
}

static void unregister_ftrace_profiler(void)
{
        unregister_ftrace_graph(&fprofiler_ops);
}
#else
static struct ftrace_ops ftrace_profile_ops __read_mostly = {
        .func           = function_profile_call,
        .flags          = FTRACE_OPS_FL_INITIALIZED,
        INIT_OPS_HASH(ftrace_profile_ops)
};

static int register_ftrace_profiler(void)
{
        return register_ftrace_function(&ftrace_profile_ops);
}

static void unregister_ftrace_profiler(void)
{
        unregister_ftrace_function(&ftrace_profile_ops);
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

static ssize_t
ftrace_profile_write(struct file *filp, const char __user *ubuf,
                     size_t cnt, loff_t *ppos)
{
        unsigned long val;
        int ret;

        ret = kstrtoul_from_user(ubuf, cnt, 10, &val);
        if (ret)
                return ret;

        val = !!val;

        mutex_lock(&ftrace_profile_lock);
        if (ftrace_profile_enabled ^ val) {
                if (val) {
                        ret = ftrace_profile_init();
                        if (ret < 0) {
                                cnt = ret;
                                goto out;
                        }

                        ret = register_ftrace_profiler();
                        if (ret < 0) {
                                cnt = ret;
                                goto out;
                        }
                        ftrace_profile_enabled = 1;
                } else {
                        ftrace_profile_enabled = 0;
                        /*
                         * unregister_ftrace_profiler calls stop_machine
                         * so this acts like an synchronize_rcu.
                         */
                        unregister_ftrace_profiler();
                }
        }
 out:
        mutex_unlock(&ftrace_profile_lock);

        *ppos += cnt;

        return cnt;
}

static ssize_t
ftrace_profile_read(struct file *filp, char __user *ubuf,
                     size_t cnt, loff_t *ppos)
{
        char buf[64];           /* big enough to hold a number */
        int r;

        r = sprintf(buf, "%u\n", ftrace_profile_enabled);
        return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}

static const struct file_operations ftrace_profile_fops = {
        .open           = tracing_open_generic,
        .read           = ftrace_profile_read,
        .write          = ftrace_profile_write,
        .llseek         = default_llseek,
};

/* used to initialize the real stat files */
static struct tracer_stat function_stats __initdata = {
        .name           = "functions",
        .stat_start     = function_stat_start,
        .stat_next      = function_stat_next,
        .stat_cmp       = function_stat_cmp,
        .stat_headers   = function_stat_headers,
        .stat_show      = function_stat_show
};

static __init void ftrace_profile_tracefs(struct dentry *d_tracer)
{
        struct ftrace_profile_stat *stat;
        char *name;
        int ret;
        int cpu;

        for_each_possible_cpu(cpu) {
                stat = &per_cpu(ftrace_profile_stats, cpu);

                name = kasprintf(GFP_KERNEL, "function%d", cpu);
                if (!name) {
                        /*
                         * The files created are permanent, if something happens
                         * we still do not free memory.
                         */
                        WARN(1,
                             "Could not allocate stat file for cpu %d\n",
                             cpu);
                        return;
                }
                stat->stat = function_stats;
                stat->stat.name = name;
                ret = register_stat_tracer(&stat->stat);
                if (ret) {
                        WARN(1,
                             "Could not register function stat for cpu %d\n",
                             cpu);
                        kfree(name);
                        return;
                }
        }

        trace_create_file("function_profile_enabled",
                          TRACE_MODE_WRITE, d_tracer, NULL,
                          &ftrace_profile_fops);
}

#else /* CONFIG_FUNCTION_PROFILER */
static __init void ftrace_profile_tracefs(struct dentry *d_tracer)
{
}
#endif /* CONFIG_FUNCTION_PROFILER */

#ifdef CONFIG_DYNAMIC_FTRACE

static struct ftrace_ops *removed_ops;

/*
 * Set when doing a global update, like enabling all recs or disabling them.
 * It is not set when just updating a single ftrace_ops.
 */
static bool update_all_ops;

#ifndef CONFIG_FTRACE_MCOUNT_RECORD
# error Dynamic ftrace depends on MCOUNT_RECORD
#endif

struct ftrace_func_probe {
        struct ftrace_probe_ops *probe_ops;
        struct ftrace_ops       ops;
        struct trace_array      *tr;
        struct list_head        list;
        void                    *data;
        int                     ref;
};

/*
 * We make these constant because no one should touch them,
 * but they are used as the default "empty hash", to avoid allocating
 * it all the time. These are in a read only section such that if
 * anyone does try to modify it, it will cause an exception.
 */
static const struct hlist_head empty_buckets[1];
static const struct ftrace_hash empty_hash = {
        .buckets = (struct hlist_head *)empty_buckets,
};
#define EMPTY_HASH      ((struct ftrace_hash *)&empty_hash)

struct ftrace_ops global_ops = {
        .func                           = ftrace_stub,
        .local_hash.notrace_hash        = EMPTY_HASH,
        .local_hash.filter_hash         = EMPTY_HASH,
        INIT_OPS_HASH(global_ops)
        .flags                          = FTRACE_OPS_FL_INITIALIZED |
                                          FTRACE_OPS_FL_PID,
};

/*
 * Used by the stack unwinder to know about dynamic ftrace trampolines.
 */
struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr)
{
        struct ftrace_ops *op = NULL;

        /*
         * Some of the ops may be dynamically allocated,
         * they are freed after a synchronize_rcu().
         */
        preempt_disable_notrace();

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                /*
                 * This is to check for dynamically allocated trampolines.
                 * Trampolines that are in kernel text will have
                 * core_kernel_text() return true.
                 */
                if (op->trampoline && op->trampoline_size)
                        if (addr >= op->trampoline &&
                            addr < op->trampoline + op->trampoline_size) {
                                preempt_enable_notrace();
                                return op;
                        }
        } while_for_each_ftrace_op(op);
        preempt_enable_notrace();

        return NULL;
}

/*
 * This is used by __kernel_text_address() to return true if the
 * address is on a dynamically allocated trampoline that would
 * not return true for either core_kernel_text() or
 * is_module_text_address().
 */
bool is_ftrace_trampoline(unsigned long addr)
{
        return ftrace_ops_trampoline(addr) != NULL;
}

struct ftrace_page {
        struct ftrace_page      *next;
        struct dyn_ftrace       *records;
        int                     index;
        int                     order;
};

#define ENTRY_SIZE sizeof(struct dyn_ftrace)
#define ENTRIES_PER_PAGE (PAGE_SIZE / ENTRY_SIZE)

static struct ftrace_page       *ftrace_pages_start;
static struct ftrace_page       *ftrace_pages;

static __always_inline unsigned long
ftrace_hash_key(struct ftrace_hash *hash, unsigned long ip)
{
        if (hash->size_bits > 0)
                return hash_long(ip, hash->size_bits);

        return 0;
}

/* Only use this function if ftrace_hash_empty() has already been tested */
static __always_inline struct ftrace_func_entry *
__ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip)
{
        unsigned long key;
        struct ftrace_func_entry *entry;
        struct hlist_head *hhd;

        key = ftrace_hash_key(hash, ip);
        hhd = &hash->buckets[key];

        hlist_for_each_entry_rcu_notrace(entry, hhd, hlist) {
                if (entry->ip == ip)
                        return entry;
        }
        return NULL;
}

/**
 * ftrace_lookup_ip - Test to see if an ip exists in an ftrace_hash
 * @hash: The hash to look at
 * @ip: The instruction pointer to test
 *
 * Search a given @hash to see if a given instruction pointer (@ip)
 * exists in it.
 *
 * Returns: the entry that holds the @ip if found. NULL otherwise.
 */
struct ftrace_func_entry *
ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip)
{
        if (ftrace_hash_empty(hash))
                return NULL;

        return __ftrace_lookup_ip(hash, ip);
}

static void __add_hash_entry(struct ftrace_hash *hash,
                             struct ftrace_func_entry *entry)
{
        struct hlist_head *hhd;
        unsigned long key;

        key = ftrace_hash_key(hash, entry->ip);
        hhd = &hash->buckets[key];
        hlist_add_head(&entry->hlist, hhd);
        hash->count++;
}

static struct ftrace_func_entry *
add_hash_entry(struct ftrace_hash *hash, unsigned long ip)
{
        struct ftrace_func_entry *entry;

        entry = kmalloc(sizeof(*entry), GFP_KERNEL);
        if (!entry)
                return NULL;

        entry->ip = ip;
        __add_hash_entry(hash, entry);

        return entry;
}

static void
free_hash_entry(struct ftrace_hash *hash,
                  struct ftrace_func_entry *entry)
{
        hlist_del(&entry->hlist);
        kfree(entry);
        hash->count--;
}

static void
remove_hash_entry(struct ftrace_hash *hash,
                  struct ftrace_func_entry *entry)
{
        hlist_del_rcu(&entry->hlist);
        hash->count--;
}

static void ftrace_hash_clear(struct ftrace_hash *hash)
{
        struct hlist_head *hhd;
        struct hlist_node *tn;
        struct ftrace_func_entry *entry;
        int size = 1 << hash->size_bits;
        int i;

        if (!hash->count)
                return;

        for (i = 0; i < size; i++) {
                hhd = &hash->buckets[i];
                hlist_for_each_entry_safe(entry, tn, hhd, hlist)
                        free_hash_entry(hash, entry);
        }
        FTRACE_WARN_ON(hash->count);
}

static void free_ftrace_mod(struct ftrace_mod_load *ftrace_mod)
{
        list_del(&ftrace_mod->list);
        kfree(ftrace_mod->module);
        kfree(ftrace_mod->func);
        kfree(ftrace_mod);
}

static void clear_ftrace_mod_list(struct list_head *head)
{
        struct ftrace_mod_load *p, *n;

        /* stack tracer isn't supported yet */
        if (!head)
                return;

        mutex_lock(&ftrace_lock);
        list_for_each_entry_safe(p, n, head, list)
                free_ftrace_mod(p);
        mutex_unlock(&ftrace_lock);
}

static void free_ftrace_hash(struct ftrace_hash *hash)
{
        if (!hash || hash == EMPTY_HASH)
                return;
        ftrace_hash_clear(hash);
        kfree(hash->buckets);
        kfree(hash);
}

static void __free_ftrace_hash_rcu(struct rcu_head *rcu)
{
        struct ftrace_hash *hash;

        hash = container_of(rcu, struct ftrace_hash, rcu);
        free_ftrace_hash(hash);
}

static void free_ftrace_hash_rcu(struct ftrace_hash *hash)
{
        if (!hash || hash == EMPTY_HASH)
                return;
        call_rcu(&hash->rcu, __free_ftrace_hash_rcu);
}

/**
 * ftrace_free_filter - remove all filters for an ftrace_ops
 * @ops: the ops to remove the filters from
 */
void ftrace_free_filter(struct ftrace_ops *ops)
{
        ftrace_ops_init(ops);
        free_ftrace_hash(ops->func_hash->filter_hash);
        free_ftrace_hash(ops->func_hash->notrace_hash);
}
EXPORT_SYMBOL_GPL(ftrace_free_filter);

static struct ftrace_hash *alloc_ftrace_hash(int size_bits)
{
        struct ftrace_hash *hash;
        int size;

        hash = kzalloc(sizeof(*hash), GFP_KERNEL);
        if (!hash)
                return NULL;

        size = 1 << size_bits;
        hash->buckets = kcalloc(size, sizeof(*hash->buckets), GFP_KERNEL);

        if (!hash->buckets) {
                kfree(hash);
                return NULL;
        }

        hash->size_bits = size_bits;

        return hash;
}


static int ftrace_add_mod(struct trace_array *tr,
                          const char *func, const char *module,
                          int enable)
{
        struct ftrace_mod_load *ftrace_mod;
        struct list_head *mod_head = enable ? &tr->mod_trace : &tr->mod_notrace;

        ftrace_mod = kzalloc(sizeof(*ftrace_mod), GFP_KERNEL);
        if (!ftrace_mod)
                return -ENOMEM;

        INIT_LIST_HEAD(&ftrace_mod->list);
        ftrace_mod->func = kstrdup(func, GFP_KERNEL);
        ftrace_mod->module = kstrdup(module, GFP_KERNEL);
        ftrace_mod->enable = enable;

        if (!ftrace_mod->func || !ftrace_mod->module)
                goto out_free;

        list_add(&ftrace_mod->list, mod_head);

        return 0;

 out_free:
        free_ftrace_mod(ftrace_mod);

        return -ENOMEM;
}

static struct ftrace_hash *
alloc_and_copy_ftrace_hash(int size_bits, struct ftrace_hash *hash)
{
        struct ftrace_func_entry *entry;
        struct ftrace_hash *new_hash;
        int size;
        int i;

        new_hash = alloc_ftrace_hash(size_bits);
        if (!new_hash)
                return NULL;

        if (hash)
                new_hash->flags = hash->flags;

        /* Empty hash? */
        if (ftrace_hash_empty(hash))
                return new_hash;

        size = 1 << hash->size_bits;
        for (i = 0; i < size; i++) {
                hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
                        if (add_hash_entry(new_hash, entry->ip) == NULL)
                                goto free_hash;
                }
        }

        FTRACE_WARN_ON(new_hash->count != hash->count);

        return new_hash;

 free_hash:
        free_ftrace_hash(new_hash);
        return NULL;
}

static void
ftrace_hash_rec_disable_modify(struct ftrace_ops *ops, int filter_hash);
static void
ftrace_hash_rec_enable_modify(struct ftrace_ops *ops, int filter_hash);

static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops,
                                       struct ftrace_hash *new_hash);

static struct ftrace_hash *dup_hash(struct ftrace_hash *src, int size)
{
        struct ftrace_func_entry *entry;
        struct ftrace_hash *new_hash;
        struct hlist_head *hhd;
        struct hlist_node *tn;
        int bits = 0;
        int i;

        /*
         * Use around half the size (max bit of it), but
         * a minimum of 2 is fine (as size of 0 or 1 both give 1 for bits).
         */
        bits = fls(size / 2);

        /* Don't allocate too much */
        if (bits > FTRACE_HASH_MAX_BITS)
                bits = FTRACE_HASH_MAX_BITS;

        new_hash = alloc_ftrace_hash(bits);
        if (!new_hash)
                return NULL;

        new_hash->flags = src->flags;

        size = 1 << src->size_bits;
        for (i = 0; i < size; i++) {
                hhd = &src->buckets[i];
                hlist_for_each_entry_safe(entry, tn, hhd, hlist) {
                        remove_hash_entry(src, entry);
                        __add_hash_entry(new_hash, entry);
                }
        }
        return new_hash;
}

static struct ftrace_hash *
__ftrace_hash_move(struct ftrace_hash *src)
{
        int size = src->count;

        /*
         * If the new source is empty, just return the empty_hash.
         */
        if (ftrace_hash_empty(src))
                return EMPTY_HASH;

        return dup_hash(src, size);
}

static int
ftrace_hash_move(struct ftrace_ops *ops, int enable,
                 struct ftrace_hash **dst, struct ftrace_hash *src)
{
        struct ftrace_hash *new_hash;
        int ret;

        /* Reject setting notrace hash on IPMODIFY ftrace_ops */
        if (ops->flags & FTRACE_OPS_FL_IPMODIFY && !enable)
                return -EINVAL;

        new_hash = __ftrace_hash_move(src);
        if (!new_hash)
                return -ENOMEM;

        /* Make sure this can be applied if it is IPMODIFY ftrace_ops */
        if (enable) {
                /* IPMODIFY should be updated only when filter_hash updating */
                ret = ftrace_hash_ipmodify_update(ops, new_hash);
                if (ret < 0) {
                        free_ftrace_hash(new_hash);
                        return ret;
                }
        }

        /*
         * Remove the current set, update the hash and add
         * them back.
         */
        ftrace_hash_rec_disable_modify(ops, enable);

        rcu_assign_pointer(*dst, new_hash);

        ftrace_hash_rec_enable_modify(ops, enable);

        return 0;
}

static bool hash_contains_ip(unsigned long ip,
                             struct ftrace_ops_hash *hash)
{
        /*
         * The function record is a match if it exists in the filter
         * hash and not in the notrace hash. Note, an empty hash is
         * considered a match for the filter hash, but an empty
         * notrace hash is considered not in the notrace hash.
         */
        return (ftrace_hash_empty(hash->filter_hash) ||
                __ftrace_lookup_ip(hash->filter_hash, ip)) &&
                (ftrace_hash_empty(hash->notrace_hash) ||
                 !__ftrace_lookup_ip(hash->notrace_hash, ip));
}

/*
 * Test the hashes for this ops to see if we want to call
 * the ops->func or not.
 *
 * It's a match if the ip is in the ops->filter_hash or
 * the filter_hash does not exist or is empty,
 *  AND
 * the ip is not in the ops->notrace_hash.
 *
 * This needs to be called with preemption disabled as
 * the hashes are freed with call_rcu().
 */
int
ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
{
        struct ftrace_ops_hash hash;
        int ret;

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
        /*
         * There's a small race when adding ops that the ftrace handler
         * that wants regs, may be called without them. We can not
         * allow that handler to be called if regs is NULL.
         */
        if (regs == NULL && (ops->flags & FTRACE_OPS_FL_SAVE_REGS))
                return 0;
#endif

        rcu_assign_pointer(hash.filter_hash, ops->func_hash->filter_hash);
        rcu_assign_pointer(hash.notrace_hash, ops->func_hash->notrace_hash);

        if (hash_contains_ip(ip, &hash))
                ret = 1;
        else
                ret = 0;

        return ret;
}

/*
 * This is a double for. Do not use 'break' to break out of the loop,
 * you must use a goto.
 */
#define do_for_each_ftrace_rec(pg, rec)                                 \
        for (pg = ftrace_pages_start; pg; pg = pg->next) {              \
                int _____i;                                             \
                for (_____i = 0; _____i < pg->index; _____i++) {        \
                        rec = &pg->records[_____i];

#define while_for_each_ftrace_rec()             \
                }                               \
        }


static int ftrace_cmp_recs(const void *a, const void *b)
{
        const struct dyn_ftrace *key = a;
        const struct dyn_ftrace *rec = b;

        if (key->flags < rec->ip)
                return -1;
        if (key->ip >= rec->ip + MCOUNT_INSN_SIZE)
                return 1;
        return 0;
}

static struct dyn_ftrace *lookup_rec(unsigned long start, unsigned long end)
{
        struct ftrace_page *pg;
        struct dyn_ftrace *rec = NULL;
        struct dyn_ftrace key;

        key.ip = start;
        key.flags = end;        /* overload flags, as it is unsigned long */

        for (pg = ftrace_pages_start; pg; pg = pg->next) {
                if (pg->index == 0 ||
                    end < pg->records[0].ip ||
                    start >= (pg->records[pg->index - 1].ip + MCOUNT_INSN_SIZE))
                        continue;
                rec = bsearch(&key, pg->records, pg->index,
                              sizeof(struct dyn_ftrace),
                              ftrace_cmp_recs);
                if (rec)
                        break;
        }
        return rec;
}

/**
 * ftrace_location_range - return the first address of a traced location
 *      if it touches the given ip range
 * @start: start of range to search.
 * @end: end of range to search (inclusive). @end points to the last byte
 *      to check.
 *
 * Returns: rec->ip if the related ftrace location is a least partly within
 * the given address range. That is, the first address of the instruction
 * that is either a NOP or call to the function tracer. It checks the ftrace
 * internal tables to determine if the address belongs or not.
 */
unsigned long ftrace_location_range(unsigned long start, unsigned long end)
{
        struct dyn_ftrace *rec;

        rec = lookup_rec(start, end);
        if (rec)
                return rec->ip;

        return 0;
}

/**
 * ftrace_location - return the ftrace location
 * @ip: the instruction pointer to check
 *
 * Returns:
 * * If @ip matches the ftrace location, return @ip.
 * * If @ip matches sym+0, return sym's ftrace location.
 * * Otherwise, return 0.
 */
unsigned long ftrace_location(unsigned long ip)
{
        struct dyn_ftrace *rec;
        unsigned long offset;
        unsigned long size;

        rec = lookup_rec(ip, ip);
        if (!rec) {
                if (!kallsyms_lookup_size_offset(ip, &size, &offset))
                        goto out;

                /* map sym+0 to __fentry__ */
                if (!offset)
                        rec = lookup_rec(ip, ip + size - 1);
        }

        if (rec)
                return rec->ip;

out:
        return 0;
}

/**
 * ftrace_text_reserved - return true if range contains an ftrace location
 * @start: start of range to search
 * @end: end of range to search (inclusive). @end points to the last byte to check.
 *
 * Returns: 1 if @start and @end contains a ftrace location.
 * That is, the instruction that is either a NOP or call to
 * the function tracer. It checks the ftrace internal tables to
 * determine if the address belongs or not.
 */
int ftrace_text_reserved(const void *start, const void *end)
{
        unsigned long ret;

        ret = ftrace_location_range((unsigned long)start,
                                    (unsigned long)end);

        return (int)!!ret;
}

/* Test if ops registered to this rec needs regs */
static bool test_rec_ops_needs_regs(struct dyn_ftrace *rec)
{
        struct ftrace_ops *ops;
        bool keep_regs = false;

        for (ops = ftrace_ops_list;
             ops != &ftrace_list_end; ops = ops->next) {
                /* pass rec in as regs to have non-NULL val */
                if (ftrace_ops_test(ops, rec->ip, rec)) {
                        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
                                keep_regs = true;
                                break;
                        }
                }
        }

        return  keep_regs;
}

static struct ftrace_ops *
ftrace_find_tramp_ops_any(struct dyn_ftrace *rec);
static struct ftrace_ops *
ftrace_find_tramp_ops_any_other(struct dyn_ftrace *rec, struct ftrace_ops *op_exclude);
static struct ftrace_ops *
ftrace_find_tramp_ops_next(struct dyn_ftrace *rec, struct ftrace_ops *ops);

static bool skip_record(struct dyn_ftrace *rec)
{
        /*
         * At boot up, weak functions are set to disable. Function tracing
         * can be enabled before they are, and they still need to be disabled now.
         * If the record is disabled, still continue if it is marked as already
         * enabled (this is needed to keep the accounting working).
         */
        return rec->flags & FTRACE_FL_DISABLED &&
                !(rec->flags & FTRACE_FL_ENABLED);
}

static bool __ftrace_hash_rec_update(struct ftrace_ops *ops,
                                     int filter_hash,
                                     bool inc)
{
        struct ftrace_hash *hash;
        struct ftrace_hash *other_hash;
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        bool update = false;
        int count = 0;
        int all = false;

        /* Only update if the ops has been registered */
        if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
                return false;

        /*
         * In the filter_hash case:
         *   If the count is zero, we update all records.
         *   Otherwise we just update the items in the hash.
         *
         * In the notrace_hash case:
         *   We enable the update in the hash.
         *   As disabling notrace means enabling the tracing,
         *   and enabling notrace means disabling, the inc variable
         *   gets inversed.
         */
        if (filter_hash) {
                hash = ops->func_hash->filter_hash;
                other_hash = ops->func_hash->notrace_hash;
                if (ftrace_hash_empty(hash))
                        all = true;
        } else {
                inc = !inc;
                hash = ops->func_hash->notrace_hash;
                other_hash = ops->func_hash->filter_hash;
                /*
                 * If the notrace hash has no items,
                 * then there's nothing to do.
                 */
                if (ftrace_hash_empty(hash))
                        return false;
        }

        do_for_each_ftrace_rec(pg, rec) {
                int in_other_hash = 0;
                int in_hash = 0;
                int match = 0;

                if (skip_record(rec))
                        continue;

                if (all) {
                        /*
                         * Only the filter_hash affects all records.
                         * Update if the record is not in the notrace hash.
                         */
                        if (!other_hash || !ftrace_lookup_ip(other_hash, rec->ip))
                                match = 1;
                } else {
                        in_hash = !!ftrace_lookup_ip(hash, rec->ip);
                        in_other_hash = !!ftrace_lookup_ip(other_hash, rec->ip);

                        /*
                         * If filter_hash is set, we want to match all functions
                         * that are in the hash but not in the other hash.
                         *
                         * If filter_hash is not set, then we are decrementing.
                         * That means we match anything that is in the hash
                         * and also in the other_hash. That is, we need to turn
                         * off functions in the other hash because they are disabled
                         * by this hash.
                         */
                        if (filter_hash && in_hash && !in_other_hash)
                                match = 1;
                        else if (!filter_hash && in_hash &&
                                 (in_other_hash || ftrace_hash_empty(other_hash)))
                                match = 1;
                }
                if (!match)
                        continue;

                if (inc) {
                        rec->flags++;
                        if (FTRACE_WARN_ON(ftrace_rec_count(rec) == FTRACE_REF_MAX))
                                return false;

                        if (ops->flags & FTRACE_OPS_FL_DIRECT)
                                rec->flags |= FTRACE_FL_DIRECT;

                        /*
                         * If there's only a single callback registered to a
                         * function, and the ops has a trampoline registered
                         * for it, then we can call it directly.
                         */
                        if (ftrace_rec_count(rec) == 1 && ops->trampoline)
                                rec->flags |= FTRACE_FL_TRAMP;
                        else
                                /*
                                 * If we are adding another function callback
                                 * to this function, and the previous had a
                                 * custom trampoline in use, then we need to go
                                 * back to the default trampoline.
                                 */
                                rec->flags &= ~FTRACE_FL_TRAMP;

                        /*
                         * If any ops wants regs saved for this function
                         * then all ops will get saved regs.
                         */
                        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
                                rec->flags |= FTRACE_FL_REGS;
                } else {
                        if (FTRACE_WARN_ON(ftrace_rec_count(rec) == 0))
                                return false;
                        rec->flags--;

                        /*
                         * Only the internal direct_ops should have the
                         * DIRECT flag set. Thus, if it is removing a
                         * function, then that function should no longer
                         * be direct.
                         */
                        if (ops->flags & FTRACE_OPS_FL_DIRECT)
                                rec->flags &= ~FTRACE_FL_DIRECT;

                        /*
                         * If the rec had REGS enabled and the ops that is
                         * being removed had REGS set, then see if there is
                         * still any ops for this record that wants regs.
                         * If not, we can stop recording them.
                         */
                        if (ftrace_rec_count(rec) > 0 &&
                            rec->flags & FTRACE_FL_REGS &&
                            ops->flags & FTRACE_OPS_FL_SAVE_REGS) {
                                if (!test_rec_ops_needs_regs(rec))
                                        rec->flags &= ~FTRACE_FL_REGS;
                        }

                        /*
                         * The TRAMP needs to be set only if rec count
                         * is decremented to one, and the ops that is
                         * left has a trampoline. As TRAMP can only be
                         * enabled if there is only a single ops attached
                         * to it.
                         */
                        if (ftrace_rec_count(rec) == 1 &&
                            ftrace_find_tramp_ops_any_other(rec, ops))
                                rec->flags |= FTRACE_FL_TRAMP;
                        else
                                rec->flags &= ~FTRACE_FL_TRAMP;

                        /*
                         * flags will be cleared in ftrace_check_record()
                         * if rec count is zero.
                         */
                }

                /*
                 * If the rec has a single associated ops, and ops->func can be
                 * called directly, allow the call site to call via the ops.
                 */
                if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS) &&
                    ftrace_rec_count(rec) == 1 &&
                    ftrace_ops_get_func(ops) == ops->func)
                        rec->flags |= FTRACE_FL_CALL_OPS;
                else
                        rec->flags &= ~FTRACE_FL_CALL_OPS;

                count++;

                /* Must match FTRACE_UPDATE_CALLS in ftrace_modify_all_code() */
                update |= ftrace_test_record(rec, true) != FTRACE_UPDATE_IGNORE;

                /* Shortcut, if we handled all records, we are done. */
                if (!all && count == hash->count)
                        return update;
        } while_for_each_ftrace_rec();

        return update;
}

static bool ftrace_hash_rec_disable(struct ftrace_ops *ops,
                                    int filter_hash)
{
        return __ftrace_hash_rec_update(ops, filter_hash, 0);
}

static bool ftrace_hash_rec_enable(struct ftrace_ops *ops,
                                   int filter_hash)
{
        return __ftrace_hash_rec_update(ops, filter_hash, 1);
}

static void ftrace_hash_rec_update_modify(struct ftrace_ops *ops,
                                          int filter_hash, int inc)
{
        struct ftrace_ops *op;

        __ftrace_hash_rec_update(ops, filter_hash, inc);

        if (ops->func_hash != &global_ops.local_hash)
                return;

        /*
         * If the ops shares the global_ops hash, then we need to update
         * all ops that are enabled and use this hash.
         */
        do_for_each_ftrace_op(op, ftrace_ops_list) {
                /* Already done */
                if (op == ops)
                        continue;
                if (op->func_hash == &global_ops.local_hash)
                        __ftrace_hash_rec_update(op, filter_hash, inc);
        } while_for_each_ftrace_op(op);
}

static void ftrace_hash_rec_disable_modify(struct ftrace_ops *ops,
                                           int filter_hash)
{
        ftrace_hash_rec_update_modify(ops, filter_hash, 0);
}

static void ftrace_hash_rec_enable_modify(struct ftrace_ops *ops,
                                          int filter_hash)
{
        ftrace_hash_rec_update_modify(ops, filter_hash, 1);
}

/*
 * Try to update IPMODIFY flag on each ftrace_rec. Return 0 if it is OK
 * or no-needed to update, -EBUSY if it detects a conflict of the flag
 * on a ftrace_rec, and -EINVAL if the new_hash tries to trace all recs.
 * Note that old_hash and new_hash has below meanings
 *  - If the hash is NULL, it hits all recs (if IPMODIFY is set, this is rejected)
 *  - If the hash is EMPTY_HASH, it hits nothing
 *  - Anything else hits the recs which match the hash entries.
 *
 * DIRECT ops does not have IPMODIFY flag, but we still need to check it
 * against functions with FTRACE_FL_IPMODIFY. If there is any overlap, call
 * ops_func(SHARE_IPMODIFY_SELF) to make sure current ops can share with
 * IPMODIFY. If ops_func(SHARE_IPMODIFY_SELF) returns non-zero, propagate
 * the return value to the caller and eventually to the owner of the DIRECT
 * ops.
 */
static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops,
                                         struct ftrace_hash *old_hash,
                                         struct ftrace_hash *new_hash)
{
        struct ftrace_page *pg;
        struct dyn_ftrace *rec, *end = NULL;
        int in_old, in_new;
        bool is_ipmodify, is_direct;

        /* Only update if the ops has been registered */
        if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
                return 0;

        is_ipmodify = ops->flags & FTRACE_OPS_FL_IPMODIFY;
        is_direct = ops->flags & FTRACE_OPS_FL_DIRECT;

        /* neither IPMODIFY nor DIRECT, skip */
        if (!is_ipmodify && !is_direct)
                return 0;

        if (WARN_ON_ONCE(is_ipmodify && is_direct))
                return 0;

        /*
         * Since the IPMODIFY and DIRECT are very address sensitive
         * actions, we do not allow ftrace_ops to set all functions to new
         * hash.
         */
        if (!new_hash || !old_hash)
                return -EINVAL;

        /* Update rec->flags */
        do_for_each_ftrace_rec(pg, rec) {

                if (rec->flags & FTRACE_FL_DISABLED)
                        continue;

                /* We need to update only differences of filter_hash */
                in_old = !!ftrace_lookup_ip(old_hash, rec->ip);
                in_new = !!ftrace_lookup_ip(new_hash, rec->ip);
                if (in_old == in_new)
                        continue;

                if (in_new) {
                        if (rec->flags & FTRACE_FL_IPMODIFY) {
                                int ret;

                                /* Cannot have two ipmodify on same rec */
                                if (is_ipmodify)
                                        goto rollback;

                                FTRACE_WARN_ON(rec->flags & FTRACE_FL_DIRECT);

                                /*
                                 * Another ops with IPMODIFY is already
                                 * attached. We are now attaching a direct
                                 * ops. Run SHARE_IPMODIFY_SELF, to check
                                 * whether sharing is supported.
                                 */
                                if (!ops->ops_func)
                                        return -EBUSY;
                                ret = ops->ops_func(ops, FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_SELF);
                                if (ret)
                                        return ret;
                        } else if (is_ipmodify) {
                                rec->flags |= FTRACE_FL_IPMODIFY;
                        }
                } else if (is_ipmodify) {
                        rec->flags &= ~FTRACE_FL_IPMODIFY;
                }
        } while_for_each_ftrace_rec();

        return 0;

rollback:
        end = rec;

        /* Roll back what we did above */
        do_for_each_ftrace_rec(pg, rec) {

                if (rec->flags & FTRACE_FL_DISABLED)
                        continue;

                if (rec == end)
                        goto err_out;

                in_old = !!ftrace_lookup_ip(old_hash, rec->ip);
                in_new = !!ftrace_lookup_ip(new_hash, rec->ip);
                if (in_old == in_new)
                        continue;

                if (in_new)
                        rec->flags &= ~FTRACE_FL_IPMODIFY;
                else
                        rec->flags |= FTRACE_FL_IPMODIFY;
        } while_for_each_ftrace_rec();

err_out:
        return -EBUSY;
}

static int ftrace_hash_ipmodify_enable(struct ftrace_ops *ops)
{
        struct ftrace_hash *hash = ops->func_hash->filter_hash;

        if (ftrace_hash_empty(hash))
                hash = NULL;

        return __ftrace_hash_update_ipmodify(ops, EMPTY_HASH, hash);
}

/* Disabling always succeeds */
static void ftrace_hash_ipmodify_disable(struct ftrace_ops *ops)
{
        struct ftrace_hash *hash = ops->func_hash->filter_hash;

        if (ftrace_hash_empty(hash))
                hash = NULL;

        __ftrace_hash_update_ipmodify(ops, hash, EMPTY_HASH);
}

static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops,
                                       struct ftrace_hash *new_hash)
{
        struct ftrace_hash *old_hash = ops->func_hash->filter_hash;

        if (ftrace_hash_empty(old_hash))
                old_hash = NULL;

        if (ftrace_hash_empty(new_hash))
                new_hash = NULL;

        return __ftrace_hash_update_ipmodify(ops, old_hash, new_hash);
}

static void print_ip_ins(const char *fmt, const unsigned char *p)
{
        char ins[MCOUNT_INSN_SIZE];

        if (copy_from_kernel_nofault(ins, p, MCOUNT_INSN_SIZE)) {
                printk(KERN_CONT "%s[FAULT] %px\n", fmt, p);
                return;
        }

        printk(KERN_CONT "%s", fmt);
        pr_cont("%*phC", MCOUNT_INSN_SIZE, ins);
}

enum ftrace_bug_type ftrace_bug_type;
const void *ftrace_expected;

static void print_bug_type(void)
{
        switch (ftrace_bug_type) {
        case FTRACE_BUG_UNKNOWN:
                break;
        case FTRACE_BUG_INIT:
                pr_info("Initializing ftrace call sites\n");
                break;
        case FTRACE_BUG_NOP:
                pr_info("Setting ftrace call site to NOP\n");
                break;
        case FTRACE_BUG_CALL:
                pr_info("Setting ftrace call site to call ftrace function\n");
                break;
        case FTRACE_BUG_UPDATE:
                pr_info("Updating ftrace call site to call a different ftrace function\n");
                break;
        }
}

/**
 * ftrace_bug - report and shutdown function tracer
 * @failed: The failed type (EFAULT, EINVAL, EPERM)
 * @rec: The record that failed
 *
 * The arch code that enables or disables the function tracing
 * can call ftrace_bug() when it has detected a problem in
 * modifying the code. @failed should be one of either:
 * EFAULT - if the problem happens on reading the @ip address
 * EINVAL - if what is read at @ip is not what was expected
 * EPERM - if the problem happens on writing to the @ip address
 */
void ftrace_bug(int failed, struct dyn_ftrace *rec)
{
        unsigned long ip = rec ? rec->ip : 0;

        pr_info("------------[ ftrace bug ]------------\n");

        switch (failed) {
        case -EFAULT:
                pr_info("ftrace faulted on modifying ");
                print_ip_sym(KERN_INFO, ip);
                break;
        case -EINVAL:
                pr_info("ftrace failed to modify ");
                print_ip_sym(KERN_INFO, ip);
                print_ip_ins(" actual:   ", (unsigned char *)ip);
                pr_cont("\n");
                if (ftrace_expected) {
                        print_ip_ins(" expected: ", ftrace_expected);
                        pr_cont("\n");
                }
                break;
        case -EPERM:
                pr_info("ftrace faulted on writing ");
                print_ip_sym(KERN_INFO, ip);
                break;
        default:
                pr_info("ftrace faulted on unknown error ");
                print_ip_sym(KERN_INFO, ip);
        }
        print_bug_type();
        if (rec) {
                struct ftrace_ops *ops = NULL;

                pr_info("ftrace record flags: %lx\n", rec->flags);
                pr_cont(" (%ld)%s%s", ftrace_rec_count(rec),
                        rec->flags & FTRACE_FL_REGS ? " R" : "  ",
                        rec->flags & FTRACE_FL_CALL_OPS ? " O" : "  ");
                if (rec->flags & FTRACE_FL_TRAMP_EN) {
                        ops = ftrace_find_tramp_ops_any(rec);
                        if (ops) {
                                do {
                                        pr_cont("\ttramp: %pS (%pS)",
                                                (void *)ops->trampoline,
                                                (void *)ops->func);
                                        ops = ftrace_find_tramp_ops_next(rec, ops);
                                } while (ops);
                        } else
                                pr_cont("\ttramp: ERROR!");

                }
                ip = ftrace_get_addr_curr(rec);
                pr_cont("\n expected tramp: %lx\n", ip);
        }

        FTRACE_WARN_ON_ONCE(1);
}

static int ftrace_check_record(struct dyn_ftrace *rec, bool enable, bool update)
{
        unsigned long flag = 0UL;

        ftrace_bug_type = FTRACE_BUG_UNKNOWN;

        if (skip_record(rec))
                return FTRACE_UPDATE_IGNORE;

        /*
         * If we are updating calls:
         *
         *   If the record has a ref count, then we need to enable it
         *   because someone is using it.
         *
         *   Otherwise we make sure its disabled.
         *
         * If we are disabling calls, then disable all records that
         * are enabled.
         */
        if (enable && ftrace_rec_count(rec))
                flag = FTRACE_FL_ENABLED;

        /*
         * If enabling and the REGS flag does not match the REGS_EN, or
         * the TRAMP flag doesn't match the TRAMP_EN, then do not ignore
         * this record. Set flags to fail the compare against ENABLED.
         * Same for direct calls.
         */
        if (flag) {
                if (!(rec->flags & FTRACE_FL_REGS) !=
                    !(rec->flags & FTRACE_FL_REGS_EN))
                        flag |= FTRACE_FL_REGS;

                if (!(rec->flags & FTRACE_FL_TRAMP) !=
                    !(rec->flags & FTRACE_FL_TRAMP_EN))
                        flag |= FTRACE_FL_TRAMP;

                /*
                 * Direct calls are special, as count matters.
                 * We must test the record for direct, if the
                 * DIRECT and DIRECT_EN do not match, but only
                 * if the count is 1. That's because, if the
                 * count is something other than one, we do not
                 * want the direct enabled (it will be done via the
                 * direct helper). But if DIRECT_EN is set, and
                 * the count is not one, we need to clear it.
                 *
                 */
                if (ftrace_rec_count(rec) == 1) {
                        if (!(rec->flags & FTRACE_FL_DIRECT) !=
                            !(rec->flags & FTRACE_FL_DIRECT_EN))
                                flag |= FTRACE_FL_DIRECT;
                } else if (rec->flags & FTRACE_FL_DIRECT_EN) {
                        flag |= FTRACE_FL_DIRECT;
                }

                /*
                 * Ops calls are special, as count matters.
                 * As with direct calls, they must only be enabled when count
                 * is one, otherwise they'll be handled via the list ops.
                 */
                if (ftrace_rec_count(rec) == 1) {
                        if (!(rec->flags & FTRACE_FL_CALL_OPS) !=
                            !(rec->flags & FTRACE_FL_CALL_OPS_EN))
                                flag |= FTRACE_FL_CALL_OPS;
                } else if (rec->flags & FTRACE_FL_CALL_OPS_EN) {
                        flag |= FTRACE_FL_CALL_OPS;
                }
        }

        /* If the state of this record hasn't changed, then do nothing */
        if ((rec->flags & FTRACE_FL_ENABLED) == flag)
                return FTRACE_UPDATE_IGNORE;

        if (flag) {
                /* Save off if rec is being enabled (for return value) */
                flag ^= rec->flags & FTRACE_FL_ENABLED;

                if (update) {
                        rec->flags |= FTRACE_FL_ENABLED | FTRACE_FL_TOUCHED;
                        if (flag & FTRACE_FL_REGS) {
                                if (rec->flags & FTRACE_FL_REGS)
                                        rec->flags |= FTRACE_FL_REGS_EN;
                                else
                                        rec->flags &= ~FTRACE_FL_REGS_EN;
                        }
                        if (flag & FTRACE_FL_TRAMP) {
                                if (rec->flags & FTRACE_FL_TRAMP)
                                        rec->flags |= FTRACE_FL_TRAMP_EN;
                                else
                                        rec->flags &= ~FTRACE_FL_TRAMP_EN;
                        }

                        /* Keep track of anything that modifies the function */
                        if (rec->flags & (FTRACE_FL_DIRECT | FTRACE_FL_IPMODIFY))
                                rec->flags |= FTRACE_FL_MODIFIED;

                        if (flag & FTRACE_FL_DIRECT) {
                                /*
                                 * If there's only one user (direct_ops helper)
                                 * then we can call the direct function
                                 * directly (no ftrace trampoline).
                                 */
                                if (ftrace_rec_count(rec) == 1) {
                                        if (rec->flags & FTRACE_FL_DIRECT)
                                                rec->flags |= FTRACE_FL_DIRECT_EN;
                                        else
                                                rec->flags &= ~FTRACE_FL_DIRECT_EN;
                                } else {
                                        /*
                                         * Can only call directly if there's
                                         * only one callback to the function.
                                         */
                                        rec->flags &= ~FTRACE_FL_DIRECT_EN;
                                }
                        }

                        if (flag & FTRACE_FL_CALL_OPS) {
                                if (ftrace_rec_count(rec) == 1) {
                                        if (rec->flags & FTRACE_FL_CALL_OPS)
                                                rec->flags |= FTRACE_FL_CALL_OPS_EN;
                                        else
                                                rec->flags &= ~FTRACE_FL_CALL_OPS_EN;
                                } else {
                                        /*
                                         * Can only call directly if there's
                                         * only one set of associated ops.
                                         */
                                        rec->flags &= ~FTRACE_FL_CALL_OPS_EN;
                                }
                        }
                }

                /*
                 * If this record is being updated from a nop, then
                 *   return UPDATE_MAKE_CALL.
                 * Otherwise,
                 *   return UPDATE_MODIFY_CALL to tell the caller to convert
                 *   from the save regs, to a non-save regs function or
                 *   vice versa, or from a trampoline call.
                 */
                if (flag & FTRACE_FL_ENABLED) {
                        ftrace_bug_type = FTRACE_BUG_CALL;
                        return FTRACE_UPDATE_MAKE_CALL;
                }

                ftrace_bug_type = FTRACE_BUG_UPDATE;
                return FTRACE_UPDATE_MODIFY_CALL;
        }

        if (update) {
                /* If there's no more users, clear all flags */
                if (!ftrace_rec_count(rec))
                        rec->flags &= FTRACE_NOCLEAR_FLAGS;
                else
                        /*
                         * Just disable the record, but keep the ops TRAMP
                         * and REGS states. The _EN flags must be disabled though.
                         */
                        rec->flags &= ~(FTRACE_FL_ENABLED | FTRACE_FL_TRAMP_EN |
                                        FTRACE_FL_REGS_EN | FTRACE_FL_DIRECT_EN |
                                        FTRACE_FL_CALL_OPS_EN);
        }

        ftrace_bug_type = FTRACE_BUG_NOP;
        return FTRACE_UPDATE_MAKE_NOP;
}

/**
 * ftrace_update_record - set a record that now is tracing or not
 * @rec: the record to update
 * @enable: set to true if the record is tracing, false to force disable
 *
 * The records that represent all functions that can be traced need
 * to be updated when tracing has been enabled.
 */
int ftrace_update_record(struct dyn_ftrace *rec, bool enable)
{
        return ftrace_check_record(rec, enable, true);
}

/**
 * ftrace_test_record - check if the record has been enabled or not
 * @rec: the record to test
 * @enable: set to true to check if enabled, false if it is disabled
 *
 * The arch code may need to test if a record is already set to
 * tracing to determine how to modify the function code that it
 * represents.
 */
int ftrace_test_record(struct dyn_ftrace *rec, bool enable)
{
        return ftrace_check_record(rec, enable, false);
}

static struct ftrace_ops *
ftrace_find_tramp_ops_any(struct dyn_ftrace *rec)
{
        struct ftrace_ops *op;
        unsigned long ip = rec->ip;

        do_for_each_ftrace_op(op, ftrace_ops_list) {

                if (!op->trampoline)
                        continue;

                if (hash_contains_ip(ip, op->func_hash))
                        return op;
        } while_for_each_ftrace_op(op);

        return NULL;
}

static struct ftrace_ops *
ftrace_find_tramp_ops_any_other(struct dyn_ftrace *rec, struct ftrace_ops *op_exclude)
{
        struct ftrace_ops *op;
        unsigned long ip = rec->ip;

        do_for_each_ftrace_op(op, ftrace_ops_list) {

                if (op == op_exclude || !op->trampoline)
                        continue;

                if (hash_contains_ip(ip, op->func_hash))
                        return op;
        } while_for_each_ftrace_op(op);

        return NULL;
}

static struct ftrace_ops *
ftrace_find_tramp_ops_next(struct dyn_ftrace *rec,
                           struct ftrace_ops *op)
{
        unsigned long ip = rec->ip;

        while_for_each_ftrace_op(op) {

                if (!op->trampoline)
                        continue;

                if (hash_contains_ip(ip, op->func_hash))
                        return op;
        }

        return NULL;
}

static struct ftrace_ops *
ftrace_find_tramp_ops_curr(struct dyn_ftrace *rec)
{
        struct ftrace_ops *op;
        unsigned long ip = rec->ip;

        /*
         * Need to check removed ops first.
         * If they are being removed, and this rec has a tramp,
         * and this rec is in the ops list, then it would be the
         * one with the tramp.
         */
        if (removed_ops) {
                if (hash_contains_ip(ip, &removed_ops->old_hash))
                        return removed_ops;
        }

        /*
         * Need to find the current trampoline for a rec.
         * Now, a trampoline is only attached to a rec if there
         * was a single 'ops' attached to it. But this can be called
         * when we are adding another op to the rec or removing the
         * current one. Thus, if the op is being added, we can
         * ignore it because it hasn't attached itself to the rec
         * yet.
         *
         * If an ops is being modified (hooking to different functions)
         * then we don't care about the new functions that are being
         * added, just the old ones (that are probably being removed).
         *
         * If we are adding an ops to a function that already is using
         * a trampoline, it needs to be removed (trampolines are only
         * for single ops connected), then an ops that is not being
         * modified also needs to be checked.
         */
        do_for_each_ftrace_op(op, ftrace_ops_list) {

                if (!op->trampoline)
                        continue;

                /*
                 * If the ops is being added, it hasn't gotten to
                 * the point to be removed from this tree yet.
                 */
                if (op->flags & FTRACE_OPS_FL_ADDING)
                        continue;


                /*
                 * If the ops is being modified and is in the old
                 * hash, then it is probably being removed from this
                 * function.
                 */
                if ((op->flags & FTRACE_OPS_FL_MODIFYING) &&
                    hash_contains_ip(ip, &op->old_hash))
                        return op;
                /*
                 * If the ops is not being added or modified, and it's
                 * in its normal filter hash, then this must be the one
                 * we want!
                 */
                if (!(op->flags & FTRACE_OPS_FL_MODIFYING) &&
                    hash_contains_ip(ip, op->func_hash))
                        return op;

        } while_for_each_ftrace_op(op);

        return NULL;
}

static struct ftrace_ops *
ftrace_find_tramp_ops_new(struct dyn_ftrace *rec)
{
        struct ftrace_ops *op;
        unsigned long ip = rec->ip;

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                /* pass rec in as regs to have non-NULL val */
                if (hash_contains_ip(ip, op->func_hash))
                        return op;
        } while_for_each_ftrace_op(op);

        return NULL;
}

struct ftrace_ops *
ftrace_find_unique_ops(struct dyn_ftrace *rec)
{
        struct ftrace_ops *op, *found = NULL;
        unsigned long ip = rec->ip;

        do_for_each_ftrace_op(op, ftrace_ops_list) {

                if (hash_contains_ip(ip, op->func_hash)) {
                        if (found)
                                return NULL;
                        found = op;
                }

        } while_for_each_ftrace_op(op);

        return found;
}

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
/* Protected by rcu_tasks for reading, and direct_mutex for writing */
static struct ftrace_hash __rcu *direct_functions = EMPTY_HASH;
static DEFINE_MUTEX(direct_mutex);
int ftrace_direct_func_count;

/*
 * Search the direct_functions hash to see if the given instruction pointer
 * has a direct caller attached to it.
 */
unsigned long ftrace_find_rec_direct(unsigned long ip)
{
        struct ftrace_func_entry *entry;

        entry = __ftrace_lookup_ip(direct_functions, ip);
        if (!entry)
                return 0;

        return entry->direct;
}

static void call_direct_funcs(unsigned long ip, unsigned long pip,
                              struct ftrace_ops *ops, struct ftrace_regs *fregs)
{
        unsigned long addr = READ_ONCE(ops->direct_call);

        if (!addr)
                return;

        arch_ftrace_set_direct_caller(fregs, addr);
}
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */

/**
 * ftrace_get_addr_new - Get the call address to set to
 * @rec:  The ftrace record descriptor
 *
 * If the record has the FTRACE_FL_REGS set, that means that it
 * wants to convert to a callback that saves all regs. If FTRACE_FL_REGS
 * is not set, then it wants to convert to the normal callback.
 *
 * Returns: the address of the trampoline to set to
 */
unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec)
{
        struct ftrace_ops *ops;
        unsigned long addr;

        if ((rec->flags & FTRACE_FL_DIRECT) &&
            (ftrace_rec_count(rec) == 1)) {
                addr = ftrace_find_rec_direct(rec->ip);
                if (addr)
                        return addr;
                WARN_ON_ONCE(1);
        }

        /* Trampolines take precedence over regs */
        if (rec->flags & FTRACE_FL_TRAMP) {
                ops = ftrace_find_tramp_ops_new(rec);
                if (FTRACE_WARN_ON(!ops || !ops->trampoline)) {
                        pr_warn("Bad trampoline accounting at: %p (%pS) (%lx)\n",
                                (void *)rec->ip, (void *)rec->ip, rec->flags);
                        /* Ftrace is shutting down, return anything */
                        return (unsigned long)FTRACE_ADDR;
                }
                return ops->trampoline;
        }

        if (rec->flags & FTRACE_FL_REGS)
                return (unsigned long)FTRACE_REGS_ADDR;
        else
                return (unsigned long)FTRACE_ADDR;
}

/**
 * ftrace_get_addr_curr - Get the call address that is already there
 * @rec:  The ftrace record descriptor
 *
 * The FTRACE_FL_REGS_EN is set when the record already points to
 * a function that saves all the regs. Basically the '_EN' version
 * represents the current state of the function.
 *
 * Returns: the address of the trampoline that is currently being called
 */
unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec)
{
        struct ftrace_ops *ops;
        unsigned long addr;

        /* Direct calls take precedence over trampolines */
        if (rec->flags & FTRACE_FL_DIRECT_EN) {
                addr = ftrace_find_rec_direct(rec->ip);
                if (addr)
                        return addr;
                WARN_ON_ONCE(1);
        }

        /* Trampolines take precedence over regs */
        if (rec->flags & FTRACE_FL_TRAMP_EN) {
                ops = ftrace_find_tramp_ops_curr(rec);
                if (FTRACE_WARN_ON(!ops)) {
                        pr_warn("Bad trampoline accounting at: %p (%pS)\n",
                                (void *)rec->ip, (void *)rec->ip);
                        /* Ftrace is shutting down, return anything */
                        return (unsigned long)FTRACE_ADDR;
                }
                return ops->trampoline;
        }

        if (rec->flags & FTRACE_FL_REGS_EN)
                return (unsigned long)FTRACE_REGS_ADDR;
        else
                return (unsigned long)FTRACE_ADDR;
}

static int
__ftrace_replace_code(struct dyn_ftrace *rec, bool enable)
{
        unsigned long ftrace_old_addr;
        unsigned long ftrace_addr;
        int ret;

        ftrace_addr = ftrace_get_addr_new(rec);

        /* This needs to be done before we call ftrace_update_record */
        ftrace_old_addr = ftrace_get_addr_curr(rec);

        ret = ftrace_update_record(rec, enable);

        ftrace_bug_type = FTRACE_BUG_UNKNOWN;

        switch (ret) {
        case FTRACE_UPDATE_IGNORE:
                return 0;

        case FTRACE_UPDATE_MAKE_CALL:
                ftrace_bug_type = FTRACE_BUG_CALL;
                return ftrace_make_call(rec, ftrace_addr);

        case FTRACE_UPDATE_MAKE_NOP:
                ftrace_bug_type = FTRACE_BUG_NOP;
                return ftrace_make_nop(NULL, rec, ftrace_old_addr);

        case FTRACE_UPDATE_MODIFY_CALL:
                ftrace_bug_type = FTRACE_BUG_UPDATE;
                return ftrace_modify_call(rec, ftrace_old_addr, ftrace_addr);
        }

        return -1; /* unknown ftrace bug */
}

void __weak ftrace_replace_code(int mod_flags)
{
        struct dyn_ftrace *rec;
        struct ftrace_page *pg;
        bool enable = mod_flags & FTRACE_MODIFY_ENABLE_FL;
        int schedulable = mod_flags & FTRACE_MODIFY_MAY_SLEEP_FL;
        int failed;

        if (unlikely(ftrace_disabled))
                return;

        do_for_each_ftrace_rec(pg, rec) {

                if (skip_record(rec))
                        continue;

                failed = __ftrace_replace_code(rec, enable);
                if (failed) {
                        ftrace_bug(failed, rec);
                        /* Stop processing */
                        return;
                }
                if (schedulable)
                        cond_resched();
        } while_for_each_ftrace_rec();
}

struct ftrace_rec_iter {
        struct ftrace_page      *pg;
        int                     index;
};

/**
 * ftrace_rec_iter_start - start up iterating over traced functions
 *
 * Returns: an iterator handle that is used to iterate over all
 * the records that represent address locations where functions
 * are traced.
 *
 * May return NULL if no records are available.
 */
struct ftrace_rec_iter *ftrace_rec_iter_start(void)
{
        /*
         * We only use a single iterator.
         * Protected by the ftrace_lock mutex.
         */
        static struct ftrace_rec_iter ftrace_rec_iter;
        struct ftrace_rec_iter *iter = &ftrace_rec_iter;

        iter->pg = ftrace_pages_start;
        iter->index = 0;

        /* Could have empty pages */
        while (iter->pg && !iter->pg->index)
                iter->pg = iter->pg->next;

        if (!iter->pg)
                return NULL;

        return iter;
}

/**
 * ftrace_rec_iter_next - get the next record to process.
 * @iter: The handle to the iterator.
 *
 * Returns: the next iterator after the given iterator @iter.
 */
struct ftrace_rec_iter *ftrace_rec_iter_next(struct ftrace_rec_iter *iter)
{
        iter->index++;

        if (iter->index >= iter->pg->index) {
                iter->pg = iter->pg->next;
                iter->index = 0;

                /* Could have empty pages */
                while (iter->pg && !iter->pg->index)
                        iter->pg = iter->pg->next;
        }

        if (!iter->pg)
                return NULL;

        return iter;
}

/**
 * ftrace_rec_iter_record - get the record at the iterator location
 * @iter: The current iterator location
 *
 * Returns: the record that the current @iter is at.
 */
struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter)
{
        return &iter->pg->records[iter->index];
}

static int
ftrace_nop_initialize(struct module *mod, struct dyn_ftrace *rec)
{
        int ret;

        if (unlikely(ftrace_disabled))
                return 0;

        ret = ftrace_init_nop(mod, rec);
        if (ret) {
                ftrace_bug_type = FTRACE_BUG_INIT;
                ftrace_bug(ret, rec);
                return 0;
        }
        return 1;
}

/*
 * archs can override this function if they must do something
 * before the modifying code is performed.
 */
void __weak ftrace_arch_code_modify_prepare(void)
{
}

/*
 * archs can override this function if they must do something
 * after the modifying code is performed.
 */
void __weak ftrace_arch_code_modify_post_process(void)
{
}

static int update_ftrace_func(ftrace_func_t func)
{
        static ftrace_func_t save_func;

        /* Avoid updating if it hasn't changed */
        if (func == save_func)
                return 0;

        save_func = func;

        return ftrace_update_ftrace_func(func);
}

void ftrace_modify_all_code(int command)
{
        int update = command & FTRACE_UPDATE_TRACE_FUNC;
        int mod_flags = 0;
        int err = 0;

        if (command & FTRACE_MAY_SLEEP)
                mod_flags = FTRACE_MODIFY_MAY_SLEEP_FL;

        /*
         * If the ftrace_caller calls a ftrace_ops func directly,
         * we need to make sure that it only traces functions it
         * expects to trace. When doing the switch of functions,
         * we need to update to the ftrace_ops_list_func first
         * before the transition between old and new calls are set,
         * as the ftrace_ops_list_func will check the ops hashes
         * to make sure the ops are having the right functions
         * traced.
         */
        if (update) {
                err = update_ftrace_func(ftrace_ops_list_func);
                if (FTRACE_WARN_ON(err))
                        return;
        }

        if (command & FTRACE_UPDATE_CALLS)
                ftrace_replace_code(mod_flags | FTRACE_MODIFY_ENABLE_FL);
        else if (command & FTRACE_DISABLE_CALLS)
                ftrace_replace_code(mod_flags);

        if (update && ftrace_trace_function != ftrace_ops_list_func) {
                function_trace_op = set_function_trace_op;
                smp_wmb();
                /* If irqs are disabled, we are in stop machine */
                if (!irqs_disabled())
                        smp_call_function(ftrace_sync_ipi, NULL, 1);
                err = update_ftrace_func(ftrace_trace_function);
                if (FTRACE_WARN_ON(err))
                        return;
        }

        if (command & FTRACE_START_FUNC_RET)
                err = ftrace_enable_ftrace_graph_caller();
        else if (command & FTRACE_STOP_FUNC_RET)
                err = ftrace_disable_ftrace_graph_caller();
        FTRACE_WARN_ON(err);
}

static int __ftrace_modify_code(void *data)
{
        int *command = data;

        ftrace_modify_all_code(*command);

        return 0;
}

/**
 * ftrace_run_stop_machine - go back to the stop machine method
 * @command: The command to tell ftrace what to do
 *
 * If an arch needs to fall back to the stop machine method, the
 * it can call this function.
 */
void ftrace_run_stop_machine(int command)
{
        stop_machine(__ftrace_modify_code, &command, NULL);
}

/**
 * arch_ftrace_update_code - modify the code to trace or not trace
 * @command: The command that needs to be done
 *
 * Archs can override this function if it does not need to
 * run stop_machine() to modify code.
 */
void __weak arch_ftrace_update_code(int command)
{
        ftrace_run_stop_machine(command);
}

static void ftrace_run_update_code(int command)
{
        ftrace_arch_code_modify_prepare();

        /*
         * By default we use stop_machine() to modify the code.
         * But archs can do what ever they want as long as it
         * is safe. The stop_machine() is the safest, but also
         * produces the most overhead.
         */
        arch_ftrace_update_code(command);

        ftrace_arch_code_modify_post_process();
}

static void ftrace_run_modify_code(struct ftrace_ops *ops, int command,
                                   struct ftrace_ops_hash *old_hash)
{
        ops->flags |= FTRACE_OPS_FL_MODIFYING;
        ops->old_hash.filter_hash = old_hash->filter_hash;
        ops->old_hash.notrace_hash = old_hash->notrace_hash;
        ftrace_run_update_code(command);
        ops->old_hash.filter_hash = NULL;
        ops->old_hash.notrace_hash = NULL;
        ops->flags &= ~FTRACE_OPS_FL_MODIFYING;
}

static ftrace_func_t saved_ftrace_func;
static int ftrace_start_up;

void __weak arch_ftrace_trampoline_free(struct ftrace_ops *ops)
{
}

/* List of trace_ops that have allocated trampolines */
static LIST_HEAD(ftrace_ops_trampoline_list);

static void ftrace_add_trampoline_to_kallsyms(struct ftrace_ops *ops)
{
        lockdep_assert_held(&ftrace_lock);
        list_add_rcu(&ops->list, &ftrace_ops_trampoline_list);
}

static void ftrace_remove_trampoline_from_kallsyms(struct ftrace_ops *ops)
{
        lockdep_assert_held(&ftrace_lock);
        list_del_rcu(&ops->list);
        synchronize_rcu();
}

/*
 * "__builtin__ftrace" is used as a module name in /proc/kallsyms for symbols
 * for pages allocated for ftrace purposes, even though "__builtin__ftrace" is
 * not a module.
 */
#define FTRACE_TRAMPOLINE_MOD "__builtin__ftrace"
#define FTRACE_TRAMPOLINE_SYM "ftrace_trampoline"

static void ftrace_trampoline_free(struct ftrace_ops *ops)
{
        if (ops && (ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP) &&
            ops->trampoline) {
                /*
                 * Record the text poke event before the ksymbol unregister
                 * event.
                 */
                perf_event_text_poke((void *)ops->trampoline,
                                     (void *)ops->trampoline,
                                     ops->trampoline_size, NULL, 0);
                perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL,
                                   ops->trampoline, ops->trampoline_size,
                                   true, FTRACE_TRAMPOLINE_SYM);
                /* Remove from kallsyms after the perf events */
                ftrace_remove_trampoline_from_kallsyms(ops);
        }

        arch_ftrace_trampoline_free(ops);
}

static void ftrace_startup_enable(int command)
{
        if (saved_ftrace_func != ftrace_trace_function) {
                saved_ftrace_func = ftrace_trace_function;
                command |= FTRACE_UPDATE_TRACE_FUNC;
        }

        if (!command || !ftrace_enabled)
                return;

        ftrace_run_update_code(command);
}

static void ftrace_startup_all(int command)
{
        update_all_ops = true;
        ftrace_startup_enable(command);
        update_all_ops = false;
}

int ftrace_startup(struct ftrace_ops *ops, int command)
{
        int ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        ret = __register_ftrace_function(ops);
        if (ret)
                return ret;

        ftrace_start_up++;

        /*
         * Note that ftrace probes uses this to start up
         * and modify functions it will probe. But we still
         * set the ADDING flag for modification, as probes
         * do not have trampolines. If they add them in the
         * future, then the probes will need to distinguish
         * between adding and updating probes.
         */
        ops->flags |= FTRACE_OPS_FL_ENABLED | FTRACE_OPS_FL_ADDING;

        ret = ftrace_hash_ipmodify_enable(ops);
        if (ret < 0) {
                /* Rollback registration process */
                __unregister_ftrace_function(ops);
                ftrace_start_up--;
                ops->flags &= ~FTRACE_OPS_FL_ENABLED;
                if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
                        ftrace_trampoline_free(ops);
                return ret;
        }

        if (ftrace_hash_rec_enable(ops, 1))
                command |= FTRACE_UPDATE_CALLS;

        ftrace_startup_enable(command);

        /*
         * If ftrace is in an undefined state, we just remove ops from list
         * to prevent the NULL pointer, instead of totally rolling it back and
         * free trampoline, because those actions could cause further damage.
         */
        if (unlikely(ftrace_disabled)) {
                __unregister_ftrace_function(ops);
                return -ENODEV;
        }

        ops->flags &= ~FTRACE_OPS_FL_ADDING;

        return 0;
}

int ftrace_shutdown(struct ftrace_ops *ops, int command)
{
        int ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        ret = __unregister_ftrace_function(ops);
        if (ret)
                return ret;

        ftrace_start_up--;
        /*
         * Just warn in case of unbalance, no need to kill ftrace, it's not
         * critical but the ftrace_call callers may be never nopped again after
         * further ftrace uses.
         */
        WARN_ON_ONCE(ftrace_start_up < 0);

        /* Disabling ipmodify never fails */
        ftrace_hash_ipmodify_disable(ops);

        if (ftrace_hash_rec_disable(ops, 1))
                command |= FTRACE_UPDATE_CALLS;

        ops->flags &= ~FTRACE_OPS_FL_ENABLED;

        if (saved_ftrace_func != ftrace_trace_function) {
                saved_ftrace_func = ftrace_trace_function;
                command |= FTRACE_UPDATE_TRACE_FUNC;
        }

        if (!command || !ftrace_enabled)
                goto out;

        /*
         * If the ops uses a trampoline, then it needs to be
         * tested first on update.
         */
        ops->flags |= FTRACE_OPS_FL_REMOVING;
        removed_ops = ops;

        /* The trampoline logic checks the old hashes */
        ops->old_hash.filter_hash = ops->func_hash->filter_hash;
        ops->old_hash.notrace_hash = ops->func_hash->notrace_hash;

        ftrace_run_update_code(command);

        /*
         * If there's no more ops registered with ftrace, run a
         * sanity check to make sure all rec flags are cleared.
         */
        if (rcu_dereference_protected(ftrace_ops_list,
                        lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
                struct ftrace_page *pg;
                struct dyn_ftrace *rec;

                do_for_each_ftrace_rec(pg, rec) {
                        if (FTRACE_WARN_ON_ONCE(rec->flags & ~FTRACE_NOCLEAR_FLAGS))
                                pr_warn("  %pS flags:%lx\n",
                                        (void *)rec->ip, rec->flags);
                } while_for_each_ftrace_rec();
        }

        ops->old_hash.filter_hash = NULL;
        ops->old_hash.notrace_hash = NULL;

        removed_ops = NULL;
        ops->flags &= ~FTRACE_OPS_FL_REMOVING;

out:
        /*
         * Dynamic ops may be freed, we must make sure that all
         * callers are done before leaving this function.
         */
        if (ops->flags & FTRACE_OPS_FL_DYNAMIC) {
                /*
                 * We need to do a hard force of sched synchronization.
                 * This is because we use preempt_disable() to do RCU, but
                 * the function tracers can be called where RCU is not watching
                 * (like before user_exit()). We can not rely on the RCU
                 * infrastructure to do the synchronization, thus we must do it
                 * ourselves.
                 */
                synchronize_rcu_tasks_rude();

                /*
                 * When the kernel is preemptive, tasks can be preempted
                 * while on a ftrace trampoline. Just scheduling a task on
                 * a CPU is not good enough to flush them. Calling
                 * synchronize_rcu_tasks() will wait for those tasks to
                 * execute and either schedule voluntarily or enter user space.
                 */
                if (IS_ENABLED(CONFIG_PREEMPTION))
                        synchronize_rcu_tasks();

                ftrace_trampoline_free(ops);
        }

        return 0;
}

static u64              ftrace_update_time;
unsigned long           ftrace_update_tot_cnt;
unsigned long           ftrace_number_of_pages;
unsigned long           ftrace_number_of_groups;

static inline int ops_traces_mod(struct ftrace_ops *ops)
{
        /*
         * Filter_hash being empty will default to trace module.
         * But notrace hash requires a test of individual module functions.
         */
        return ftrace_hash_empty(ops->func_hash->filter_hash) &&
                ftrace_hash_empty(ops->func_hash->notrace_hash);
}

static int ftrace_update_code(struct module *mod, struct ftrace_page *new_pgs)
{
        bool init_nop = ftrace_need_init_nop();
        struct ftrace_page *pg;
        struct dyn_ftrace *p;
        u64 start, stop;
        unsigned long update_cnt = 0;
        unsigned long rec_flags = 0;
        int i;

        start = ftrace_now(raw_smp_processor_id());

        /*
         * When a module is loaded, this function is called to convert
         * the calls to mcount in its text to nops, and also to create
         * an entry in the ftrace data. Now, if ftrace is activated
         * after this call, but before the module sets its text to
         * read-only, the modification of enabling ftrace can fail if
         * the read-only is done while ftrace is converting the calls.
         * To prevent this, the module's records are set as disabled
         * and will be enabled after the call to set the module's text
         * to read-only.
         */
        if (mod)
                rec_flags |= FTRACE_FL_DISABLED;

        for (pg = new_pgs; pg; pg = pg->next) {

                for (i = 0; i < pg->index; i++) {

                        /* If something went wrong, bail without enabling anything */
                        if (unlikely(ftrace_disabled))
                                return -1;

                        p = &pg->records[i];
                        p->flags = rec_flags;

                        /*
                         * Do the initial record conversion from mcount jump
                         * to the NOP instructions.
                         */
                        if (init_nop && !ftrace_nop_initialize(mod, p))
                                break;

                        update_cnt++;
                }
        }

        stop = ftrace_now(raw_smp_processor_id());
        ftrace_update_time = stop - start;
        ftrace_update_tot_cnt += update_cnt;

        return 0;
}

static int ftrace_allocate_records(struct ftrace_page *pg, int count)
{
        int order;
        int pages;
        int cnt;

        if (WARN_ON(!count))
                return -EINVAL;

        /* We want to fill as much as possible, with no empty pages */
        pages = DIV_ROUND_UP(count, ENTRIES_PER_PAGE);
        order = fls(pages) - 1;

 again:
        pg->records = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, order);

        if (!pg->records) {
                /* if we can't allocate this size, try something smaller */
                if (!order)
                        return -ENOMEM;
                order--;
                goto again;
        }

        ftrace_number_of_pages += 1 << order;
        ftrace_number_of_groups++;

        cnt = (PAGE_SIZE << order) / ENTRY_SIZE;
        pg->order = order;

        if (cnt > count)
                cnt = count;

        return cnt;
}

static void ftrace_free_pages(struct ftrace_page *pages)
{
        struct ftrace_page *pg = pages;

        while (pg) {
                if (pg->records) {
                        free_pages((unsigned long)pg->records, pg->order);
                        ftrace_number_of_pages -= 1 << pg->order;
                }
                pages = pg->next;
                kfree(pg);
                pg = pages;
                ftrace_number_of_groups--;
        }
}

static struct ftrace_page *
ftrace_allocate_pages(unsigned long num_to_init)
{
        struct ftrace_page *start_pg;
        struct ftrace_page *pg;
        int cnt;

        if (!num_to_init)
                return NULL;

        start_pg = pg = kzalloc(sizeof(*pg), GFP_KERNEL);
        if (!pg)
                return NULL;

        /*
         * Try to allocate as much as possible in one continues
         * location that fills in all of the space. We want to
         * waste as little space as possible.
         */
        for (;;) {
                cnt = ftrace_allocate_records(pg, num_to_init);
                if (cnt < 0)
                        goto free_pages;

                num_to_init -= cnt;
                if (!num_to_init)
                        break;

                pg->next = kzalloc(sizeof(*pg), GFP_KERNEL);
                if (!pg->next)
                        goto free_pages;

                pg = pg->next;
        }

        return start_pg;

 free_pages:
        ftrace_free_pages(start_pg);
        pr_info("ftrace: FAILED to allocate memory for functions\n");
        return NULL;
}

#define FTRACE_BUFF_MAX (KSYM_SYMBOL_LEN+4) /* room for wildcards */

struct ftrace_iterator {
        loff_t                          pos;
        loff_t                          func_pos;
        loff_t                          mod_pos;
        struct ftrace_page              *pg;
        struct dyn_ftrace               *func;
        struct ftrace_func_probe        *probe;
        struct ftrace_func_entry        *probe_entry;
        struct trace_parser             parser;
        struct ftrace_hash              *hash;
        struct ftrace_ops               *ops;
        struct trace_array              *tr;
        struct list_head                *mod_list;
        int                             pidx;
        int                             idx;
        unsigned                        flags;
};

static void *
t_probe_next(struct seq_file *m, loff_t *pos)
{
        struct ftrace_iterator *iter = m->private;
        struct trace_array *tr = iter->ops->private;
        struct list_head *func_probes;
        struct ftrace_hash *hash;
        struct list_head *next;
        struct hlist_node *hnd = NULL;
        struct hlist_head *hhd;
        int size;

        (*pos)++;
        iter->pos = *pos;

        if (!tr)
                return NULL;

        func_probes = &tr->func_probes;
        if (list_empty(func_probes))
                return NULL;

        if (!iter->probe) {
                next = func_probes->next;
                iter->probe = list_entry(next, struct ftrace_func_probe, list);
        }

        if (iter->probe_entry)
                hnd = &iter->probe_entry->hlist;

        hash = iter->probe->ops.func_hash->filter_hash;

        /*
         * A probe being registered may temporarily have an empty hash
         * and it's at the end of the func_probes list.
         */
        if (!hash || hash == EMPTY_HASH)
                return NULL;

        size = 1 << hash->size_bits;

 retry:
        if (iter->pidx >= size) {
                if (iter->probe->list.next == func_probes)
                        return NULL;
                next = iter->probe->list.next;
                iter->probe = list_entry(next, struct ftrace_func_probe, list);
                hash = iter->probe->ops.func_hash->filter_hash;
                size = 1 << hash->size_bits;
                iter->pidx = 0;
        }

        hhd = &hash->buckets[iter->pidx];

        if (hlist_empty(hhd)) {
                iter->pidx++;
                hnd = NULL;
                goto retry;
        }

        if (!hnd)
                hnd = hhd->first;
        else {
                hnd = hnd->next;
                if (!hnd) {
                        iter->pidx++;
                        goto retry;
                }
        }

        if (WARN_ON_ONCE(!hnd))
                return NULL;

        iter->probe_entry = hlist_entry(hnd, struct ftrace_func_entry, hlist);

        return iter;
}

static void *t_probe_start(struct seq_file *m, loff_t *pos)
{
        struct ftrace_iterator *iter = m->private;
        void *p = NULL;
        loff_t l;

        if (!(iter->flags & FTRACE_ITER_DO_PROBES))
                return NULL;

        if (iter->mod_pos > *pos)
                return NULL;

        iter->probe = NULL;
        iter->probe_entry = NULL;
        iter->pidx = 0;
        for (l = 0; l <= (*pos - iter->mod_pos); ) {
                p = t_probe_next(m, &l);
                if (!p)
                        break;
        }
        if (!p)
                return NULL;

        /* Only set this if we have an item */
        iter->flags |= FTRACE_ITER_PROBE;

        return iter;
}

static int
t_probe_show(struct seq_file *m, struct ftrace_iterator *iter)
{
        struct ftrace_func_entry *probe_entry;
        struct ftrace_probe_ops *probe_ops;
        struct ftrace_func_probe *probe;

        probe = iter->probe;
        probe_entry = iter->probe_entry;

        if (WARN_ON_ONCE(!probe || !probe_entry))
                return -EIO;

        probe_ops = probe->probe_ops;

        if (probe_ops->print)
                return probe_ops->print(m, probe_entry->ip, probe_ops, probe->data);

        seq_printf(m, "%ps:%ps\n", (void *)probe_entry->ip,
                   (void *)probe_ops->func);

        return 0;
}

static void *
t_mod_next(struct seq_file *m, loff_t *pos)
{
        struct ftrace_iterator *iter = m->private;
        struct trace_array *tr = iter->tr;

        (*pos)++;
        iter->pos = *pos;

        iter->mod_list = iter->mod_list->next;

        if (iter->mod_list == &tr->mod_trace ||
            iter->mod_list == &tr->mod_notrace) {
                iter->flags &= ~FTRACE_ITER_MOD;
                return NULL;
        }

        iter->mod_pos = *pos;

        return iter;
}

static void *t_mod_start(struct seq_file *m, loff_t *pos)
{
        struct ftrace_iterator *iter = m->private;
        void *p = NULL;
        loff_t l;

        if (iter->func_pos > *pos)
                return NULL;

        iter->mod_pos = iter->func_pos;

        /* probes are only available if tr is set */
        if (!iter->tr)
                return NULL;

        for (l = 0; l <= (*pos - iter->func_pos); ) {
                p = t_mod_next(m, &l);
                if (!p)
                        break;
        }
        if (!p) {
                iter->flags &= ~FTRACE_ITER_MOD;
                return t_probe_start(m, pos);
        }

        /* Only set this if we have an item */
        iter->flags |= FTRACE_ITER_MOD;

        return iter;
}

static int
t_mod_show(struct seq_file *m, struct ftrace_iterator *iter)
{
        struct ftrace_mod_load *ftrace_mod;
        struct trace_array *tr = iter->tr;

        if (WARN_ON_ONCE(!iter->mod_list) ||
                         iter->mod_list == &tr->mod_trace ||
                         iter->mod_list == &tr->mod_notrace)
                return -EIO;

        ftrace_mod = list_entry(iter->mod_list, struct ftrace_mod_load, list);

        if (ftrace_mod->func)
                seq_printf(m, "%s", ftrace_mod->func);
        else
                seq_putc(m, '*');

        seq_printf(m, ":mod:%s\n", ftrace_mod->module);

        return 0;
}

static void *
t_func_next(struct seq_file *m, loff_t *pos)
{
        struct ftrace_iterator *iter = m->private;
        struct dyn_ftrace *rec = NULL;

        (*pos)++;

 retry:
        if (iter->idx >= iter->pg->index) {
                if (iter->pg->next) {
                        iter->pg = iter->pg->next;
                        iter->idx = 0;
                        goto retry;
                }
        } else {
                rec = &iter->pg->records[iter->idx++];
                if (((iter->flags & (FTRACE_ITER_FILTER | FTRACE_ITER_NOTRACE)) &&
                     !ftrace_lookup_ip(iter->hash, rec->ip)) ||

                    ((iter->flags & FTRACE_ITER_ENABLED) &&
                     !(rec->flags & FTRACE_FL_ENABLED)) ||

                    ((iter->flags & FTRACE_ITER_TOUCHED) &&
                     !(rec->flags & FTRACE_FL_TOUCHED))) {

                        rec = NULL;
                        goto retry;
                }
        }

        if (!rec)
                return NULL;

        iter->pos = iter->func_pos = *pos;
        iter->func = rec;

        return iter;
}

static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct ftrace_iterator *iter = m->private;
        loff_t l = *pos; /* t_probe_start() must use original pos */
        void *ret;

        if (unlikely(ftrace_disabled))
                return NULL;

        if (iter->flags & FTRACE_ITER_PROBE)
                return t_probe_next(m, pos);

        if (iter->flags & FTRACE_ITER_MOD)
                return t_mod_next(m, pos);

        if (iter->flags & FTRACE_ITER_PRINTALL) {
                /* next must increment pos, and t_probe_start does not */
                (*pos)++;
                return t_mod_start(m, &l);
        }

        ret = t_func_next(m, pos);

        if (!ret)
                return t_mod_start(m, &l);

        return ret;
}

static void reset_iter_read(struct ftrace_iterator *iter)
{
        iter->pos = 0;
        iter->func_pos = 0;
        iter->flags &= ~(FTRACE_ITER_PRINTALL | FTRACE_ITER_PROBE | FTRACE_ITER_MOD);
}

static void *t_start(struct seq_file *m, loff_t *pos)
{
        struct ftrace_iterator *iter = m->private;
        void *p = NULL;
        loff_t l;

        mutex_lock(&ftrace_lock);

        if (unlikely(ftrace_disabled))
                return NULL;

        /*
         * If an lseek was done, then reset and start from beginning.
         */
        if (*pos < iter->pos)
                reset_iter_read(iter);

        /*
         * For set_ftrace_filter reading, if we have the filter
         * off, we can short cut and just print out that all
         * functions are enabled.
         */
        if ((iter->flags & (FTRACE_ITER_FILTER | FTRACE_ITER_NOTRACE)) &&
            ftrace_hash_empty(iter->hash)) {
                iter->func_pos = 1; /* Account for the message */
                if (*pos > 0)
                        return t_mod_start(m, pos);
                iter->flags |= FTRACE_ITER_PRINTALL;
                /* reset in case of seek/pread */
                iter->flags &= ~FTRACE_ITER_PROBE;
                return iter;
        }

        if (iter->flags & FTRACE_ITER_MOD)
                return t_mod_start(m, pos);

        /*
         * Unfortunately, we need to restart at ftrace_pages_start
         * every time we let go of the ftrace_mutex. This is because
         * those pointers can change without the lock.
         */
        iter->pg = ftrace_pages_start;
        iter->idx = 0;
        for (l = 0; l <= *pos; ) {
                p = t_func_next(m, &l);
                if (!p)
                        break;
        }

        if (!p)
                return t_mod_start(m, pos);

        return iter;
}

static void t_stop(struct seq_file *m, void *p)
{
        mutex_unlock(&ftrace_lock);
}

void * __weak
arch_ftrace_trampoline_func(struct ftrace_ops *ops, struct dyn_ftrace *rec)
{
        return NULL;
}

static void add_trampoline_func(struct seq_file *m, struct ftrace_ops *ops,
                                struct dyn_ftrace *rec)
{
        void *ptr;

        ptr = arch_ftrace_trampoline_func(ops, rec);
        if (ptr)
                seq_printf(m, " ->%pS", ptr);
}

#ifdef FTRACE_MCOUNT_MAX_OFFSET
/*
 * Weak functions can still have an mcount/fentry that is saved in
 * the __mcount_loc section. These can be detected by having a
 * symbol offset of greater than FTRACE_MCOUNT_MAX_OFFSET, as the
 * symbol found by kallsyms is not the function that the mcount/fentry
 * is part of. The offset is much greater in these cases.
 *
 * Test the record to make sure that the ip points to a valid kallsyms
 * and if not, mark it disabled.
 */
static int test_for_valid_rec(struct dyn_ftrace *rec)
{
        char str[KSYM_SYMBOL_LEN];
        unsigned long offset;
        const char *ret;

        ret = kallsyms_lookup(rec->ip, NULL, &offset, NULL, str);

        /* Weak functions can cause invalid addresses */
        if (!ret || offset > FTRACE_MCOUNT_MAX_OFFSET) {
                rec->flags |= FTRACE_FL_DISABLED;
                return 0;
        }
        return 1;
}

static struct workqueue_struct *ftrace_check_wq __initdata;
static struct work_struct ftrace_check_work __initdata;

/*
 * Scan all the mcount/fentry entries to make sure they are valid.
 */
static __init void ftrace_check_work_func(struct work_struct *work)
{
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;

        mutex_lock(&ftrace_lock);
        do_for_each_ftrace_rec(pg, rec) {
                test_for_valid_rec(rec);
        } while_for_each_ftrace_rec();
        mutex_unlock(&ftrace_lock);
}

static int __init ftrace_check_for_weak_functions(void)
{
        INIT_WORK(&ftrace_check_work, ftrace_check_work_func);

        ftrace_check_wq = alloc_workqueue("ftrace_check_wq", WQ_UNBOUND, 0);

        queue_work(ftrace_check_wq, &ftrace_check_work);
        return 0;
}

static int __init ftrace_check_sync(void)
{
        /* Make sure the ftrace_check updates are finished */
        if (ftrace_check_wq)
                destroy_workqueue(ftrace_check_wq);
        return 0;
}

late_initcall_sync(ftrace_check_sync);
subsys_initcall(ftrace_check_for_weak_functions);

static int print_rec(struct seq_file *m, unsigned long ip)
{
        unsigned long offset;
        char str[KSYM_SYMBOL_LEN];
        char *modname;
        const char *ret;

        ret = kallsyms_lookup(ip, NULL, &offset, &modname, str);
        /* Weak functions can cause invalid addresses */
        if (!ret || offset > FTRACE_MCOUNT_MAX_OFFSET) {
                snprintf(str, KSYM_SYMBOL_LEN, "%s_%ld",
                         FTRACE_INVALID_FUNCTION, offset);
                ret = NULL;
        }

        seq_puts(m, str);
        if (modname)
                seq_printf(m, " [%s]", modname);
        return ret == NULL ? -1 : 0;
}
#else
static inline int test_for_valid_rec(struct dyn_ftrace *rec)
{
        return 1;
}

static inline int print_rec(struct seq_file *m, unsigned long ip)
{
        seq_printf(m, "%ps", (void *)ip);
        return 0;
}
#endif

static int t_show(struct seq_file *m, void *v)
{
        struct ftrace_iterator *iter = m->private;
        struct dyn_ftrace *rec;

        if (iter->flags & FTRACE_ITER_PROBE)
                return t_probe_show(m, iter);

        if (iter->flags & FTRACE_ITER_MOD)
                return t_mod_show(m, iter);

        if (iter->flags & FTRACE_ITER_PRINTALL) {
                if (iter->flags & FTRACE_ITER_NOTRACE)
                        seq_puts(m, "#### no functions disabled ####\n");
                else
                        seq_puts(m, "#### all functions enabled ####\n");
                return 0;
        }

        rec = iter->func;

        if (!rec)
                return 0;

        if (iter->flags & FTRACE_ITER_ADDRS)
                seq_printf(m, "%lx ", rec->ip);

        if (print_rec(m, rec->ip)) {
                /* This should only happen when a rec is disabled */
                WARN_ON_ONCE(!(rec->flags & FTRACE_FL_DISABLED));
                seq_putc(m, '\n');
                return 0;
        }

        if (iter->flags & (FTRACE_ITER_ENABLED | FTRACE_ITER_TOUCHED)) {
                struct ftrace_ops *ops;

                seq_printf(m, " (%ld)%s%s%s%s%s",
                           ftrace_rec_count(rec),
                           rec->flags & FTRACE_FL_REGS ? " R" : "  ",
                           rec->flags & FTRACE_FL_IPMODIFY ? " I" : "  ",
                           rec->flags & FTRACE_FL_DIRECT ? " D" : "  ",
                           rec->flags & FTRACE_FL_CALL_OPS ? " O" : "  ",
                           rec->flags & FTRACE_FL_MODIFIED ? " M " : "   ");
                if (rec->flags & FTRACE_FL_TRAMP_EN) {
                        ops = ftrace_find_tramp_ops_any(rec);
                        if (ops) {
                                do {
                                        seq_printf(m, "\ttramp: %pS (%pS)",
                                                   (void *)ops->trampoline,
                                                   (void *)ops->func);
                                        add_trampoline_func(m, ops, rec);
                                        ops = ftrace_find_tramp_ops_next(rec, ops);
                                } while (ops);
                        } else
                                seq_puts(m, "\ttramp: ERROR!");
                } else {
                        add_trampoline_func(m, NULL, rec);
                }
                if (rec->flags & FTRACE_FL_CALL_OPS_EN) {
                        ops = ftrace_find_unique_ops(rec);
                        if (ops) {
                                seq_printf(m, "\tops: %pS (%pS)",
                                           ops, ops->func);
                        } else {
                                seq_puts(m, "\tops: ERROR!");
                        }
                }
                if (rec->flags & FTRACE_FL_DIRECT) {
                        unsigned long direct;

                        direct = ftrace_find_rec_direct(rec->ip);
                        if (direct)
                                seq_printf(m, "\n\tdirect-->%pS", (void *)direct);
                }
        }

        seq_putc(m, '\n');

        return 0;
}

static const struct seq_operations show_ftrace_seq_ops = {
        .start = t_start,
        .next = t_next,
        .stop = t_stop,
        .show = t_show,
};

static int
ftrace_avail_open(struct inode *inode, struct file *file)
{
        struct ftrace_iterator *iter;
        int ret;

        ret = security_locked_down(LOCKDOWN_TRACEFS);
        if (ret)
                return ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
        if (!iter)
                return -ENOMEM;

        iter->pg = ftrace_pages_start;
        iter->ops = &global_ops;

        return 0;
}

static int
ftrace_enabled_open(struct inode *inode, struct file *file)
{
        struct ftrace_iterator *iter;

        /*
         * This shows us what functions are currently being
         * traced and by what. Not sure if we want lockdown
         * to hide such critical information for an admin.
         * Although, perhaps it can show information we don't
         * want people to see, but if something is tracing
         * something, we probably want to know about it.
         */

        iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
        if (!iter)
                return -ENOMEM;

        iter->pg = ftrace_pages_start;
        iter->flags = FTRACE_ITER_ENABLED;
        iter->ops = &global_ops;

        return 0;
}

static int
ftrace_touched_open(struct inode *inode, struct file *file)
{
        struct ftrace_iterator *iter;

        /*
         * This shows us what functions have ever been enabled
         * (traced, direct, patched, etc). Not sure if we want lockdown
         * to hide such critical information for an admin.
         * Although, perhaps it can show information we don't
         * want people to see, but if something had traced
         * something, we probably want to know about it.
         */

        iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
        if (!iter)
                return -ENOMEM;

        iter->pg = ftrace_pages_start;
        iter->flags = FTRACE_ITER_TOUCHED;
        iter->ops = &global_ops;

        return 0;
}

static int
ftrace_avail_addrs_open(struct inode *inode, struct file *file)
{
        struct ftrace_iterator *iter;
        int ret;

        ret = security_locked_down(LOCKDOWN_TRACEFS);
        if (ret)
                return ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        iter = __seq_open_private(file, &show_ftrace_seq_ops, sizeof(*iter));
        if (!iter)
                return -ENOMEM;

        iter->pg = ftrace_pages_start;
        iter->flags = FTRACE_ITER_ADDRS;
        iter->ops = &global_ops;

        return 0;
}

/**
 * ftrace_regex_open - initialize function tracer filter files
 * @ops: The ftrace_ops that hold the hash filters
 * @flag: The type of filter to process
 * @inode: The inode, usually passed in to your open routine
 * @file: The file, usually passed in to your open routine
 *
 * ftrace_regex_open() initializes the filter files for the
 * @ops. Depending on @flag it may process the filter hash or
 * the notrace hash of @ops. With this called from the open
 * routine, you can use ftrace_filter_write() for the write
 * routine if @flag has FTRACE_ITER_FILTER set, or
 * ftrace_notrace_write() if @flag has FTRACE_ITER_NOTRACE set.
 * tracing_lseek() should be used as the lseek routine, and
 * release must call ftrace_regex_release().
 *
 * Returns: 0 on success or a negative errno value on failure
 */
int
ftrace_regex_open(struct ftrace_ops *ops, int flag,
                  struct inode *inode, struct file *file)
{
        struct ftrace_iterator *iter;
        struct ftrace_hash *hash;
        struct list_head *mod_head;
        struct trace_array *tr = ops->private;
        int ret = -ENOMEM;

        ftrace_ops_init(ops);

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        if (tracing_check_open_get_tr(tr))
                return -ENODEV;

        iter = kzalloc(sizeof(*iter), GFP_KERNEL);
        if (!iter)
                goto out;

        if (trace_parser_get_init(&iter->parser, FTRACE_BUFF_MAX))
                goto out;

        iter->ops = ops;
        iter->flags = flag;
        iter->tr = tr;

        mutex_lock(&ops->func_hash->regex_lock);

        if (flag & FTRACE_ITER_NOTRACE) {
                hash = ops->func_hash->notrace_hash;
                mod_head = tr ? &tr->mod_notrace : NULL;
        } else {
                hash = ops->func_hash->filter_hash;
                mod_head = tr ? &tr->mod_trace : NULL;
        }

        iter->mod_list = mod_head;

        if (file->f_mode & FMODE_WRITE) {
                const int size_bits = FTRACE_HASH_DEFAULT_BITS;

                if (file->f_flags & O_TRUNC) {
                        iter->hash = alloc_ftrace_hash(size_bits);
                        clear_ftrace_mod_list(mod_head);
                } else {
                        iter->hash = alloc_and_copy_ftrace_hash(size_bits, hash);
                }

                if (!iter->hash) {
                        trace_parser_put(&iter->parser);
                        goto out_unlock;
                }
        } else
                iter->hash = hash;

        ret = 0;

        if (file->f_mode & FMODE_READ) {
                iter->pg = ftrace_pages_start;

                ret = seq_open(file, &show_ftrace_seq_ops);
                if (!ret) {
                        struct seq_file *m = file->private_data;
                        m->private = iter;
                } else {
                        /* Failed */
                        free_ftrace_hash(iter->hash);
                        trace_parser_put(&iter->parser);
                }
        } else
                file->private_data = iter;

 out_unlock:
        mutex_unlock(&ops->func_hash->regex_lock);

 out:
        if (ret) {
                kfree(iter);
                if (tr)
                        trace_array_put(tr);
        }

        return ret;
}

static int
ftrace_filter_open(struct inode *inode, struct file *file)
{
        struct ftrace_ops *ops = inode->i_private;

        /* Checks for tracefs lockdown */
        return ftrace_regex_open(ops,
                        FTRACE_ITER_FILTER | FTRACE_ITER_DO_PROBES,
                        inode, file);
}

static int
ftrace_notrace_open(struct inode *inode, struct file *file)
{
        struct ftrace_ops *ops = inode->i_private;

        /* Checks for tracefs lockdown */
        return ftrace_regex_open(ops, FTRACE_ITER_NOTRACE,
                                 inode, file);
}

/* Type for quick search ftrace basic regexes (globs) from filter_parse_regex */
struct ftrace_glob {
        char *search;
        unsigned len;
        int type;
};

/*
 * If symbols in an architecture don't correspond exactly to the user-visible
 * name of what they represent, it is possible to define this function to
 * perform the necessary adjustments.
*/
char * __weak arch_ftrace_match_adjust(char *str, const char *search)
{
        return str;
}

static int ftrace_match(char *str, struct ftrace_glob *g)
{
        int matched = 0;
        int slen;

        str = arch_ftrace_match_adjust(str, g->search);

        switch (g->type) {
        case MATCH_FULL:
                if (strcmp(str, g->search) == 0)
                        matched = 1;
                break;
        case MATCH_FRONT_ONLY:
                if (strncmp(str, g->search, g->len) == 0)
                        matched = 1;
                break;
        case MATCH_MIDDLE_ONLY:
                if (strstr(str, g->search))
                        matched = 1;
                break;
        case MATCH_END_ONLY:
                slen = strlen(str);
                if (slen >= g->len &&
                    memcmp(str + slen - g->len, g->search, g->len) == 0)
                        matched = 1;
                break;
        case MATCH_GLOB:
                if (glob_match(g->search, str))
                        matched = 1;
                break;
        }

        return matched;
}

static int
enter_record(struct ftrace_hash *hash, struct dyn_ftrace *rec, int clear_filter)
{
        struct ftrace_func_entry *entry;
        int ret = 0;

        entry = ftrace_lookup_ip(hash, rec->ip);
        if (clear_filter) {
                /* Do nothing if it doesn't exist */
                if (!entry)
                        return 0;

                free_hash_entry(hash, entry);
        } else {
                /* Do nothing if it exists */
                if (entry)
                        return 0;
                if (add_hash_entry(hash, rec->ip) == NULL)
                        ret = -ENOMEM;
        }
        return ret;
}

static int
add_rec_by_index(struct ftrace_hash *hash, struct ftrace_glob *func_g,
                 int clear_filter)
{
        long index = simple_strtoul(func_g->search, NULL, 0);
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;

        /* The index starts at 1 */
        if (--index < 0)
                return 0;

        do_for_each_ftrace_rec(pg, rec) {
                if (pg->index <= index) {
                        index -= pg->index;
                        /* this is a double loop, break goes to the next page */
                        break;
                }
                rec = &pg->records[index];
                enter_record(hash, rec, clear_filter);
                return 1;
        } while_for_each_ftrace_rec();
        return 0;
}

#ifdef FTRACE_MCOUNT_MAX_OFFSET
static int lookup_ip(unsigned long ip, char **modname, char *str)
{
        unsigned long offset;

        kallsyms_lookup(ip, NULL, &offset, modname, str);
        if (offset > FTRACE_MCOUNT_MAX_OFFSET)
                return -1;
        return 0;
}
#else
static int lookup_ip(unsigned long ip, char **modname, char *str)
{
        kallsyms_lookup(ip, NULL, NULL, modname, str);
        return 0;
}
#endif

static int
ftrace_match_record(struct dyn_ftrace *rec, struct ftrace_glob *func_g,
                struct ftrace_glob *mod_g, int exclude_mod)
{
        char str[KSYM_SYMBOL_LEN];
        char *modname;

        if (lookup_ip(rec->ip, &modname, str)) {
                /* This should only happen when a rec is disabled */
                WARN_ON_ONCE(system_state == SYSTEM_RUNNING &&
                             !(rec->flags & FTRACE_FL_DISABLED));
                return 0;
        }

        if (mod_g) {
                int mod_matches = (modname) ? ftrace_match(modname, mod_g) : 0;

                /* blank module name to match all modules */
                if (!mod_g->len) {
                        /* blank module globbing: modname xor exclude_mod */
                        if (!exclude_mod != !modname)
                                goto func_match;
                        return 0;
                }

                /*
                 * exclude_mod is set to trace everything but the given
                 * module. If it is set and the module matches, then
                 * return 0. If it is not set, and the module doesn't match
                 * also return 0. Otherwise, check the function to see if
                 * that matches.
                 */
                if (!mod_matches == !exclude_mod)
                        return 0;
func_match:
                /* blank search means to match all funcs in the mod */
                if (!func_g->len)
                        return 1;
        }

        return ftrace_match(str, func_g);
}

static int
match_records(struct ftrace_hash *hash, char *func, int len, char *mod)
{
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        struct ftrace_glob func_g = { .type = MATCH_FULL };
        struct ftrace_glob mod_g = { .type = MATCH_FULL };
        struct ftrace_glob *mod_match = (mod) ? &mod_g : NULL;
        int exclude_mod = 0;
        int found = 0;
        int ret;
        int clear_filter = 0;

        if (func) {
                func_g.type = filter_parse_regex(func, len, &func_g.search,
                                                 &clear_filter);
                func_g.len = strlen(func_g.search);
        }

        if (mod) {
                mod_g.type = filter_parse_regex(mod, strlen(mod),
                                &mod_g.search, &exclude_mod);
                mod_g.len = strlen(mod_g.search);
        }

        mutex_lock(&ftrace_lock);

        if (unlikely(ftrace_disabled))
                goto out_unlock;

        if (func_g.type == MATCH_INDEX) {
                found = add_rec_by_index(hash, &func_g, clear_filter);
                goto out_unlock;
        }

        do_for_each_ftrace_rec(pg, rec) {

                if (rec->flags & FTRACE_FL_DISABLED)
                        continue;

                if (ftrace_match_record(rec, &func_g, mod_match, exclude_mod)) {
                        ret = enter_record(hash, rec, clear_filter);
                        if (ret < 0) {
                                found = ret;
                                goto out_unlock;
                        }
                        found = 1;
                }
                cond_resched();
        } while_for_each_ftrace_rec();
 out_unlock:
        mutex_unlock(&ftrace_lock);

        return found;
}

static int
ftrace_match_records(struct ftrace_hash *hash, char *buff, int len)
{
        return match_records(hash, buff, len, NULL);
}

static void ftrace_ops_update_code(struct ftrace_ops *ops,
                                   struct ftrace_ops_hash *old_hash)
{
        struct ftrace_ops *op;

        if (!ftrace_enabled)
                return;

        if (ops->flags & FTRACE_OPS_FL_ENABLED) {
                ftrace_run_modify_code(ops, FTRACE_UPDATE_CALLS, old_hash);
                return;
        }

        /*
         * If this is the shared global_ops filter, then we need to
         * check if there is another ops that shares it, is enabled.
         * If so, we still need to run the modify code.
         */
        if (ops->func_hash != &global_ops.local_hash)
                return;

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                if (op->func_hash == &global_ops.local_hash &&
                    op->flags & FTRACE_OPS_FL_ENABLED) {
                        ftrace_run_modify_code(op, FTRACE_UPDATE_CALLS, old_hash);
                        /* Only need to do this once */
                        return;
                }
        } while_for_each_ftrace_op(op);
}

static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops,
                                           struct ftrace_hash **orig_hash,
                                           struct ftrace_hash *hash,
                                           int enable)
{
        struct ftrace_ops_hash old_hash_ops;
        struct ftrace_hash *old_hash;
        int ret;

        old_hash = *orig_hash;
        old_hash_ops.filter_hash = ops->func_hash->filter_hash;
        old_hash_ops.notrace_hash = ops->func_hash->notrace_hash;
        ret = ftrace_hash_move(ops, enable, orig_hash, hash);
        if (!ret) {
                ftrace_ops_update_code(ops, &old_hash_ops);
                free_ftrace_hash_rcu(old_hash);
        }
        return ret;
}

static bool module_exists(const char *module)
{
        /* All modules have the symbol __this_module */
        static const char this_mod[] = "__this_module";
        char modname[MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 2];
        unsigned long val;
        int n;

        n = snprintf(modname, sizeof(modname), "%s:%s", module, this_mod);

        if (n > sizeof(modname) - 1)
                return false;

        val = module_kallsyms_lookup_name(modname);
        return val != 0;
}

static int cache_mod(struct trace_array *tr,
                     const char *func, char *module, int enable)
{
        struct ftrace_mod_load *ftrace_mod, *n;
        struct list_head *head = enable ? &tr->mod_trace : &tr->mod_notrace;
        int ret;

        mutex_lock(&ftrace_lock);

        /* We do not cache inverse filters */
        if (func[0] == '!') {
                func++;
                ret = -EINVAL;

                /* Look to remove this hash */
                list_for_each_entry_safe(ftrace_mod, n, head, list) {
                        if (strcmp(ftrace_mod->module, module) != 0)
                                continue;

                        /* no func matches all */
                        if (strcmp(func, "*") == 0 ||
                            (ftrace_mod->func &&
                             strcmp(ftrace_mod->func, func) == 0)) {
                                ret = 0;
                                free_ftrace_mod(ftrace_mod);
                                continue;
                        }
                }
                goto out;
        }

        ret = -EINVAL;
        /* We only care about modules that have not been loaded yet */
        if (module_exists(module))
                goto out;

        /* Save this string off, and execute it when the module is loaded */
        ret = ftrace_add_mod(tr, func, module, enable);
 out:
        mutex_unlock(&ftrace_lock);

        return ret;
}

static int
ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
                 int reset, int enable);

#ifdef CONFIG_MODULES
static void process_mod_list(struct list_head *head, struct ftrace_ops *ops,
                             char *mod, bool enable)
{
        struct ftrace_mod_load *ftrace_mod, *n;
        struct ftrace_hash **orig_hash, *new_hash;
        LIST_HEAD(process_mods);
        char *func;

        mutex_lock(&ops->func_hash->regex_lock);

        if (enable)
                orig_hash = &ops->func_hash->filter_hash;
        else
                orig_hash = &ops->func_hash->notrace_hash;

        new_hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS,
                                              *orig_hash);
        if (!new_hash)
                goto out; /* warn? */

        mutex_lock(&ftrace_lock);

        list_for_each_entry_safe(ftrace_mod, n, head, list) {

                if (strcmp(ftrace_mod->module, mod) != 0)
                        continue;

                if (ftrace_mod->func)
                        func = kstrdup(ftrace_mod->func, GFP_KERNEL);
                else
                        func = kstrdup("*", GFP_KERNEL);

                if (!func) /* warn? */
                        continue;

                list_move(&ftrace_mod->list, &process_mods);

                /* Use the newly allocated func, as it may be "*" */
                kfree(ftrace_mod->func);
                ftrace_mod->func = func;
        }

        mutex_unlock(&ftrace_lock);

        list_for_each_entry_safe(ftrace_mod, n, &process_mods, list) {

                func = ftrace_mod->func;

                /* Grabs ftrace_lock, which is why we have this extra step */
                match_records(new_hash, func, strlen(func), mod);
                free_ftrace_mod(ftrace_mod);
        }

        if (enable && list_empty(head))
                new_hash->flags &= ~FTRACE_HASH_FL_MOD;

        mutex_lock(&ftrace_lock);

        ftrace_hash_move_and_update_ops(ops, orig_hash,
                                              new_hash, enable);
        mutex_unlock(&ftrace_lock);

 out:
        mutex_unlock(&ops->func_hash->regex_lock);

        free_ftrace_hash(new_hash);
}

static void process_cached_mods(const char *mod_name)
{
        struct trace_array *tr;
        char *mod;

        mod = kstrdup(mod_name, GFP_KERNEL);
        if (!mod)
                return;

        mutex_lock(&trace_types_lock);
        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
                if (!list_empty(&tr->mod_trace))
                        process_mod_list(&tr->mod_trace, tr->ops, mod, true);
                if (!list_empty(&tr->mod_notrace))
                        process_mod_list(&tr->mod_notrace, tr->ops, mod, false);
        }
        mutex_unlock(&trace_types_lock);

        kfree(mod);
}
#endif

/*
 * We register the module command as a template to show others how
 * to register the a command as well.
 */

static int
ftrace_mod_callback(struct trace_array *tr, struct ftrace_hash *hash,
                    char *func_orig, char *cmd, char *module, int enable)
{
        char *func;
        int ret;

        /* match_records() modifies func, and we need the original */
        func = kstrdup(func_orig, GFP_KERNEL);
        if (!func)
                return -ENOMEM;

        /*
         * cmd == 'mod' because we only registered this func
         * for the 'mod' ftrace_func_command.
         * But if you register one func with multiple commands,
         * you can tell which command was used by the cmd
         * parameter.
         */
        ret = match_records(hash, func, strlen(func), module);
        kfree(func);

        if (!ret)
                return cache_mod(tr, func_orig, module, enable);
        if (ret < 0)
                return ret;
        return 0;
}

static struct ftrace_func_command ftrace_mod_cmd = {
        .name                   = "mod",
        .func                   = ftrace_mod_callback,
};

static int __init ftrace_mod_cmd_init(void)
{
        return register_ftrace_command(&ftrace_mod_cmd);
}
core_initcall(ftrace_mod_cmd_init);

static void function_trace_probe_call(unsigned long ip, unsigned long parent_ip,
                                      struct ftrace_ops *op, struct ftrace_regs *fregs)
{
        struct ftrace_probe_ops *probe_ops;
        struct ftrace_func_probe *probe;

        probe = container_of(op, struct ftrace_func_probe, ops);
        probe_ops = probe->probe_ops;

        /*
         * Disable preemption for these calls to prevent a RCU grace
         * period. This syncs the hash iteration and freeing of items
         * on the hash. rcu_read_lock is too dangerous here.
         */
        preempt_disable_notrace();
        probe_ops->func(ip, parent_ip, probe->tr, probe_ops, probe->data);
        preempt_enable_notrace();
}

struct ftrace_func_map {
        struct ftrace_func_entry        entry;
        void                            *data;
};

struct ftrace_func_mapper {
        struct ftrace_hash              hash;
};

/**
 * allocate_ftrace_func_mapper - allocate a new ftrace_func_mapper
 *
 * Returns: a ftrace_func_mapper descriptor that can be used to map ips to data.
 */
struct ftrace_func_mapper *allocate_ftrace_func_mapper(void)
{
        struct ftrace_hash *hash;

        /*
         * The mapper is simply a ftrace_hash, but since the entries
         * in the hash are not ftrace_func_entry type, we define it
         * as a separate structure.
         */
        hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
        return (struct ftrace_func_mapper *)hash;
}

/**
 * ftrace_func_mapper_find_ip - Find some data mapped to an ip
 * @mapper: The mapper that has the ip maps
 * @ip: the instruction pointer to find the data for
 *
 * Returns: the data mapped to @ip if found otherwise NULL. The return
 * is actually the address of the mapper data pointer. The address is
 * returned for use cases where the data is no bigger than a long, and
 * the user can use the data pointer as its data instead of having to
 * allocate more memory for the reference.
 */
void **ftrace_func_mapper_find_ip(struct ftrace_func_mapper *mapper,
                                  unsigned long ip)
{
        struct ftrace_func_entry *entry;
        struct ftrace_func_map *map;

        entry = ftrace_lookup_ip(&mapper->hash, ip);
        if (!entry)
                return NULL;

        map = (struct ftrace_func_map *)entry;
        return &map->data;
}

/**
 * ftrace_func_mapper_add_ip - Map some data to an ip
 * @mapper: The mapper that has the ip maps
 * @ip: The instruction pointer address to map @data to
 * @data: The data to map to @ip
 *
 * Returns: 0 on success otherwise an error.
 */
int ftrace_func_mapper_add_ip(struct ftrace_func_mapper *mapper,
                              unsigned long ip, void *data)
{
        struct ftrace_func_entry *entry;
        struct ftrace_func_map *map;

        entry = ftrace_lookup_ip(&mapper->hash, ip);
        if (entry)
                return -EBUSY;

        map = kmalloc(sizeof(*map), GFP_KERNEL);
        if (!map)
                return -ENOMEM;

        map->entry.ip = ip;
        map->data = data;

        __add_hash_entry(&mapper->hash, &map->entry);

        return 0;
}

/**
 * ftrace_func_mapper_remove_ip - Remove an ip from the mapping
 * @mapper: The mapper that has the ip maps
 * @ip: The instruction pointer address to remove the data from
 *
 * Returns: the data if it is found, otherwise NULL.
 * Note, if the data pointer is used as the data itself, (see
 * ftrace_func_mapper_find_ip(), then the return value may be meaningless,
 * if the data pointer was set to zero.
 */
void *ftrace_func_mapper_remove_ip(struct ftrace_func_mapper *mapper,
                                   unsigned long ip)
{
        struct ftrace_func_entry *entry;
        struct ftrace_func_map *map;
        void *data;

        entry = ftrace_lookup_ip(&mapper->hash, ip);
        if (!entry)
                return NULL;

        map = (struct ftrace_func_map *)entry;
        data = map->data;

        remove_hash_entry(&mapper->hash, entry);
        kfree(entry);

        return data;
}

/**
 * free_ftrace_func_mapper - free a mapping of ips and data
 * @mapper: The mapper that has the ip maps
 * @free_func: A function to be called on each data item.
 *
 * This is used to free the function mapper. The @free_func is optional
 * and can be used if the data needs to be freed as well.
 */
void free_ftrace_func_mapper(struct ftrace_func_mapper *mapper,
                             ftrace_mapper_func free_func)
{
        struct ftrace_func_entry *entry;
        struct ftrace_func_map *map;
        struct hlist_head *hhd;
        int size, i;

        if (!mapper)
                return;

        if (free_func && mapper->hash.count) {
                size = 1 << mapper->hash.size_bits;
                for (i = 0; i < size; i++) {
                        hhd = &mapper->hash.buckets[i];
                        hlist_for_each_entry(entry, hhd, hlist) {
                                map = (struct ftrace_func_map *)entry;
                                free_func(map);
                        }
                }
        }
        free_ftrace_hash(&mapper->hash);
}

static void release_probe(struct ftrace_func_probe *probe)
{
        struct ftrace_probe_ops *probe_ops;

        mutex_lock(&ftrace_lock);

        WARN_ON(probe->ref <= 0);

        /* Subtract the ref that was used to protect this instance */
        probe->ref--;

        if (!probe->ref) {
                probe_ops = probe->probe_ops;
                /*
                 * Sending zero as ip tells probe_ops to free
                 * the probe->data itself
                 */
                if (probe_ops->free)
                        probe_ops->free(probe_ops, probe->tr, 0, probe->data);
                list_del(&probe->list);
                kfree(probe);
        }
        mutex_unlock(&ftrace_lock);
}

static void acquire_probe_locked(struct ftrace_func_probe *probe)
{
        /*
         * Add one ref to keep it from being freed when releasing the
         * ftrace_lock mutex.
         */
        probe->ref++;
}

int
register_ftrace_function_probe(char *glob, struct trace_array *tr,
                               struct ftrace_probe_ops *probe_ops,
                               void *data)
{
        struct ftrace_func_probe *probe = NULL, *iter;
        struct ftrace_func_entry *entry;
        struct ftrace_hash **orig_hash;
        struct ftrace_hash *old_hash;
        struct ftrace_hash *hash;
        int count = 0;
        int size;
        int ret;
        int i;

        if (WARN_ON(!tr))
                return -EINVAL;

        /* We do not support '!' for function probes */
        if (WARN_ON(glob[0] == '!'))
                return -EINVAL;


        mutex_lock(&ftrace_lock);
        /* Check if the probe_ops is already registered */
        list_for_each_entry(iter, &tr->func_probes, list) {
                if (iter->probe_ops == probe_ops) {
                        probe = iter;
                        break;
                }
        }
        if (!probe) {
                probe = kzalloc(sizeof(*probe), GFP_KERNEL);
                if (!probe) {
                        mutex_unlock(&ftrace_lock);
                        return -ENOMEM;
                }
                probe->probe_ops = probe_ops;
                probe->ops.func = function_trace_probe_call;
                probe->tr = tr;
                ftrace_ops_init(&probe->ops);
                list_add(&probe->list, &tr->func_probes);
        }

        acquire_probe_locked(probe);

        mutex_unlock(&ftrace_lock);

        /*
         * Note, there's a small window here that the func_hash->filter_hash
         * may be NULL or empty. Need to be careful when reading the loop.
         */
        mutex_lock(&probe->ops.func_hash->regex_lock);

        orig_hash = &probe->ops.func_hash->filter_hash;
        old_hash = *orig_hash;
        hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, old_hash);

        if (!hash) {
                ret = -ENOMEM;
                goto out;
        }

        ret = ftrace_match_records(hash, glob, strlen(glob));

        /* Nothing found? */
        if (!ret)
                ret = -EINVAL;

        if (ret < 0)
                goto out;

        size = 1 << hash->size_bits;
        for (i = 0; i < size; i++) {
                hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
                        if (ftrace_lookup_ip(old_hash, entry->ip))
                                continue;
                        /*
                         * The caller might want to do something special
                         * for each function we find. We call the callback
                         * to give the caller an opportunity to do so.
                         */
                        if (probe_ops->init) {
                                ret = probe_ops->init(probe_ops, tr,
                                                      entry->ip, data,
                                                      &probe->data);
                                if (ret < 0) {
                                        if (probe_ops->free && count)
                                                probe_ops->free(probe_ops, tr,
                                                                0, probe->data);
                                        probe->data = NULL;
                                        goto out;
                                }
                        }
                        count++;
                }
        }

        mutex_lock(&ftrace_lock);

        if (!count) {
                /* Nothing was added? */
                ret = -EINVAL;
                goto out_unlock;
        }

        ret = ftrace_hash_move_and_update_ops(&probe->ops, orig_hash,
                                              hash, 1);
        if (ret < 0)
                goto err_unlock;

        /* One ref for each new function traced */
        probe->ref += count;

        if (!(probe->ops.flags & FTRACE_OPS_FL_ENABLED))
                ret = ftrace_startup(&probe->ops, 0);

 out_unlock:
        mutex_unlock(&ftrace_lock);

        if (!ret)
                ret = count;
 out:
        mutex_unlock(&probe->ops.func_hash->regex_lock);
        free_ftrace_hash(hash);

        release_probe(probe);

        return ret;

 err_unlock:
        if (!probe_ops->free || !count)
                goto out_unlock;

        /* Failed to do the move, need to call the free functions */
        for (i = 0; i < size; i++) {
                hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
                        if (ftrace_lookup_ip(old_hash, entry->ip))
                                continue;
                        probe_ops->free(probe_ops, tr, entry->ip, probe->data);
                }
        }
        goto out_unlock;
}

int
unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
                                      struct ftrace_probe_ops *probe_ops)
{
        struct ftrace_func_probe *probe = NULL, *iter;
        struct ftrace_ops_hash old_hash_ops;
        struct ftrace_func_entry *entry;
        struct ftrace_glob func_g;
        struct ftrace_hash **orig_hash;
        struct ftrace_hash *old_hash;
        struct ftrace_hash *hash = NULL;
        struct hlist_node *tmp;
        struct hlist_head hhd;
        char str[KSYM_SYMBOL_LEN];
        int count = 0;
        int i, ret = -ENODEV;
        int size;

        if (!glob || !strlen(glob) || !strcmp(glob, "*"))
                func_g.search = NULL;
        else {
                int not;

                func_g.type = filter_parse_regex(glob, strlen(glob),
                                                 &func_g.search, &not);
                func_g.len = strlen(func_g.search);

                /* we do not support '!' for function probes */
                if (WARN_ON(not))
                        return -EINVAL;
        }

        mutex_lock(&ftrace_lock);
        /* Check if the probe_ops is already registered */
        list_for_each_entry(iter, &tr->func_probes, list) {
                if (iter->probe_ops == probe_ops) {
                        probe = iter;
                        break;
                }
        }
        if (!probe)
                goto err_unlock_ftrace;

        ret = -EINVAL;
        if (!(probe->ops.flags & FTRACE_OPS_FL_INITIALIZED))
                goto err_unlock_ftrace;

        acquire_probe_locked(probe);

        mutex_unlock(&ftrace_lock);

        mutex_lock(&probe->ops.func_hash->regex_lock);

        orig_hash = &probe->ops.func_hash->filter_hash;
        old_hash = *orig_hash;

        if (ftrace_hash_empty(old_hash))
                goto out_unlock;

        old_hash_ops.filter_hash = old_hash;
        /* Probes only have filters */
        old_hash_ops.notrace_hash = NULL;

        ret = -ENOMEM;
        hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, old_hash);
        if (!hash)
                goto out_unlock;

        INIT_HLIST_HEAD(&hhd);

        size = 1 << hash->size_bits;
        for (i = 0; i < size; i++) {
                hlist_for_each_entry_safe(entry, tmp, &hash->buckets[i], hlist) {

                        if (func_g.search) {
                                kallsyms_lookup(entry->ip, NULL, NULL,
                                                NULL, str);
                                if (!ftrace_match(str, &func_g))
                                        continue;
                        }
                        count++;
                        remove_hash_entry(hash, entry);
                        hlist_add_head(&entry->hlist, &hhd);
                }
        }

        /* Nothing found? */
        if (!count) {
                ret = -EINVAL;
                goto out_unlock;
        }

        mutex_lock(&ftrace_lock);

        WARN_ON(probe->ref < count);

        probe->ref -= count;

        if (ftrace_hash_empty(hash))
                ftrace_shutdown(&probe->ops, 0);

        ret = ftrace_hash_move_and_update_ops(&probe->ops, orig_hash,
                                              hash, 1);

        /* still need to update the function call sites */
        if (ftrace_enabled && !ftrace_hash_empty(hash))
                ftrace_run_modify_code(&probe->ops, FTRACE_UPDATE_CALLS,
                                       &old_hash_ops);
        synchronize_rcu();

        hlist_for_each_entry_safe(entry, tmp, &hhd, hlist) {
                hlist_del(&entry->hlist);
                if (probe_ops->free)
                        probe_ops->free(probe_ops, tr, entry->ip, probe->data);
                kfree(entry);
        }
        mutex_unlock(&ftrace_lock);

 out_unlock:
        mutex_unlock(&probe->ops.func_hash->regex_lock);
        free_ftrace_hash(hash);

        release_probe(probe);

        return ret;

 err_unlock_ftrace:
        mutex_unlock(&ftrace_lock);
        return ret;
}

void clear_ftrace_function_probes(struct trace_array *tr)
{
        struct ftrace_func_probe *probe, *n;

        list_for_each_entry_safe(probe, n, &tr->func_probes, list)
                unregister_ftrace_function_probe_func(NULL, tr, probe->probe_ops);
}

static LIST_HEAD(ftrace_commands);
static DEFINE_MUTEX(ftrace_cmd_mutex);

/*
 * Currently we only register ftrace commands from __init, so mark this
 * __init too.
 */
__init int register_ftrace_command(struct ftrace_func_command *cmd)
{
        struct ftrace_func_command *p;
        int ret = 0;

        mutex_lock(&ftrace_cmd_mutex);
        list_for_each_entry(p, &ftrace_commands, list) {
                if (strcmp(cmd->name, p->name) == 0) {
                        ret = -EBUSY;
                        goto out_unlock;
                }
        }
        list_add(&cmd->list, &ftrace_commands);
 out_unlock:
        mutex_unlock(&ftrace_cmd_mutex);

        return ret;
}

/*
 * Currently we only unregister ftrace commands from __init, so mark
 * this __init too.
 */
__init int unregister_ftrace_command(struct ftrace_func_command *cmd)
{
        struct ftrace_func_command *p, *n;
        int ret = -ENODEV;

        mutex_lock(&ftrace_cmd_mutex);
        list_for_each_entry_safe(p, n, &ftrace_commands, list) {
                if (strcmp(cmd->name, p->name) == 0) {
                        ret = 0;
                        list_del_init(&p->list);
                        goto out_unlock;
                }
        }
 out_unlock:
        mutex_unlock(&ftrace_cmd_mutex);

        return ret;
}

static int ftrace_process_regex(struct ftrace_iterator *iter,
                                char *buff, int len, int enable)
{
        struct ftrace_hash *hash = iter->hash;
        struct trace_array *tr = iter->ops->private;
        char *func, *command, *next = buff;
        struct ftrace_func_command *p;
        int ret = -EINVAL;

        func = strsep(&next, ":");

        if (!next) {
                ret = ftrace_match_records(hash, func, len);
                if (!ret)
                        ret = -EINVAL;
                if (ret < 0)
                        return ret;
                return 0;
        }

        /* command found */

        command = strsep(&next, ":");

        mutex_lock(&ftrace_cmd_mutex);
        list_for_each_entry(p, &ftrace_commands, list) {
                if (strcmp(p->name, command) == 0) {
                        ret = p->func(tr, hash, func, command, next, enable);
                        goto out_unlock;
                }
        }
 out_unlock:
        mutex_unlock(&ftrace_cmd_mutex);

        return ret;
}

static ssize_t
ftrace_regex_write(struct file *file, const char __user *ubuf,
                   size_t cnt, loff_t *ppos, int enable)
{
        struct ftrace_iterator *iter;
        struct trace_parser *parser;
        ssize_t ret, read;

        if (!cnt)
                return 0;

        if (file->f_mode & FMODE_READ) {
                struct seq_file *m = file->private_data;
                iter = m->private;
        } else
                iter = file->private_data;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        /* iter->hash is a local copy, so we don't need regex_lock */

        parser = &iter->parser;
        read = trace_get_user(parser, ubuf, cnt, ppos);

        if (read >= 0 && trace_parser_loaded(parser) &&
            !trace_parser_cont(parser)) {
                ret = ftrace_process_regex(iter, parser->buffer,
                                           parser->idx, enable);
                trace_parser_clear(parser);
                if (ret < 0)
                        goto out;
        }

        ret = read;
 out:
        return ret;
}

ssize_t
ftrace_filter_write(struct file *file, const char __user *ubuf,
                    size_t cnt, loff_t *ppos)
{
        return ftrace_regex_write(file, ubuf, cnt, ppos, 1);
}

ssize_t
ftrace_notrace_write(struct file *file, const char __user *ubuf,
                     size_t cnt, loff_t *ppos)
{
        return ftrace_regex_write(file, ubuf, cnt, ppos, 0);
}

static int
__ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove)
{
        struct ftrace_func_entry *entry;

        ip = ftrace_location(ip);
        if (!ip)
                return -EINVAL;

        if (remove) {
                entry = ftrace_lookup_ip(hash, ip);
                if (!entry)
                        return -ENOENT;
                free_hash_entry(hash, entry);
                return 0;
        }

        entry = add_hash_entry(hash, ip);
        return entry ? 0 :  -ENOMEM;
}

static int
ftrace_match_addr(struct ftrace_hash *hash, unsigned long *ips,
                  unsigned int cnt, int remove)
{
        unsigned int i;
        int err;

        for (i = 0; i < cnt; i++) {
                err = __ftrace_match_addr(hash, ips[i], remove);
                if (err) {
                        /*
                         * This expects the @hash is a temporary hash and if this
                         * fails the caller must free the @hash.
                         */
                        return err;
                }
        }
        return 0;
}

static int
ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
                unsigned long *ips, unsigned int cnt,
                int remove, int reset, int enable)
{
        struct ftrace_hash **orig_hash;
        struct ftrace_hash *hash;
        int ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        mutex_lock(&ops->func_hash->regex_lock);

        if (enable)
                orig_hash = &ops->func_hash->filter_hash;
        else
                orig_hash = &ops->func_hash->notrace_hash;

        if (reset)
                hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
        else
                hash = alloc_and_copy_ftrace_hash(FTRACE_HASH_DEFAULT_BITS, *orig_hash);

        if (!hash) {
                ret = -ENOMEM;
                goto out_regex_unlock;
        }

        if (buf && !ftrace_match_records(hash, buf, len)) {
                ret = -EINVAL;
                goto out_regex_unlock;
        }
        if (ips) {
                ret = ftrace_match_addr(hash, ips, cnt, remove);
                if (ret < 0)
                        goto out_regex_unlock;
        }

        mutex_lock(&ftrace_lock);
        ret = ftrace_hash_move_and_update_ops(ops, orig_hash, hash, enable);
        mutex_unlock(&ftrace_lock);

 out_regex_unlock:
        mutex_unlock(&ops->func_hash->regex_lock);

        free_ftrace_hash(hash);
        return ret;
}

static int
ftrace_set_addr(struct ftrace_ops *ops, unsigned long *ips, unsigned int cnt,
                int remove, int reset, int enable)
{
        return ftrace_set_hash(ops, NULL, 0, ips, cnt, remove, reset, enable);
}

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS

struct ftrace_direct_func {
        struct list_head        next;
        unsigned long           addr;
        int                     count;
};

static LIST_HEAD(ftrace_direct_funcs);

static int register_ftrace_function_nolock(struct ftrace_ops *ops);

/*
 * If there are multiple ftrace_ops, use SAVE_REGS by default, so that direct
 * call will be jumped from ftrace_regs_caller. Only if the architecture does
 * not support ftrace_regs_caller but direct_call, use SAVE_ARGS so that it
 * jumps from ftrace_caller for multiple ftrace_ops.
 */
#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_REGS
#define MULTI_FLAGS (FTRACE_OPS_FL_DIRECT | FTRACE_OPS_FL_SAVE_ARGS)
#else
#define MULTI_FLAGS (FTRACE_OPS_FL_DIRECT | FTRACE_OPS_FL_SAVE_REGS)
#endif

static int check_direct_multi(struct ftrace_ops *ops)
{
        if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED))
                return -EINVAL;
        if ((ops->flags & MULTI_FLAGS) != MULTI_FLAGS)
                return -EINVAL;
        return 0;
}

static void remove_direct_functions_hash(struct ftrace_hash *hash, unsigned long addr)
{
        struct ftrace_func_entry *entry, *del;
        int size, i;

        size = 1 << hash->size_bits;
        for (i = 0; i < size; i++) {
                hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
                        del = __ftrace_lookup_ip(direct_functions, entry->ip);
                        if (del && del->direct == addr) {
                                remove_hash_entry(direct_functions, del);
                                kfree(del);
                        }
                }
        }
}

/**
 * register_ftrace_direct - Call a custom trampoline directly
 * for multiple functions registered in @ops
 * @ops: The address of the struct ftrace_ops object
 * @addr: The address of the trampoline to call at @ops functions
 *
 * This is used to connect a direct calls to @addr from the nop locations
 * of the functions registered in @ops (with by ftrace_set_filter_ip
 * function).
 *
 * The location that it calls (@addr) must be able to handle a direct call,
 * and save the parameters of the function being traced, and restore them
 * (or inject new ones if needed), before returning.
 *
 * Returns:
 *  0 on success
 *  -EINVAL  - The @ops object was already registered with this call or
 *             when there are no functions in @ops object.
 *  -EBUSY   - Another direct function is already attached (there can be only one)
 *  -ENODEV  - @ip does not point to a ftrace nop location (or not supported)
 *  -ENOMEM  - There was an allocation failure.
 */
int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
{
        struct ftrace_hash *hash, *new_hash = NULL, *free_hash = NULL;
        struct ftrace_func_entry *entry, *new;
        int err = -EBUSY, size, i;

        if (ops->func || ops->trampoline)
                return -EINVAL;
        if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED))
                return -EINVAL;
        if (ops->flags & FTRACE_OPS_FL_ENABLED)
                return -EINVAL;

        hash = ops->func_hash->filter_hash;
        if (ftrace_hash_empty(hash))
                return -EINVAL;

        mutex_lock(&direct_mutex);

        /* Make sure requested entries are not already registered.. */
        size = 1 << hash->size_bits;
        for (i = 0; i < size; i++) {
                hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
                        if (ftrace_find_rec_direct(entry->ip))
                                goto out_unlock;
                }
        }

        err = -ENOMEM;

        /* Make a copy hash to place the new and the old entries in */
        size = hash->count + direct_functions->count;
        if (size > 32)
                size = 32;
        new_hash = alloc_ftrace_hash(fls(size));
        if (!new_hash)
                goto out_unlock;

        /* Now copy over the existing direct entries */
        size = 1 << direct_functions->size_bits;
        for (i = 0; i < size; i++) {
                hlist_for_each_entry(entry, &direct_functions->buckets[i], hlist) {
                        new = add_hash_entry(new_hash, entry->ip);
                        if (!new)
                                goto out_unlock;
                        new->direct = entry->direct;
                }
        }

        /* ... and add the new entries */
        size = 1 << hash->size_bits;
        for (i = 0; i < size; i++) {
                hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
                        new = add_hash_entry(new_hash, entry->ip);
                        if (!new)
                                goto out_unlock;
                        /* Update both the copy and the hash entry */
                        new->direct = addr;
                        entry->direct = addr;
                }
        }

        free_hash = direct_functions;
        rcu_assign_pointer(direct_functions, new_hash);
        new_hash = NULL;

        ops->func = call_direct_funcs;
        ops->flags = MULTI_FLAGS;
        ops->trampoline = FTRACE_REGS_ADDR;
        ops->direct_call = addr;

        err = register_ftrace_function_nolock(ops);

 out_unlock:
        mutex_unlock(&direct_mutex);

        if (free_hash && free_hash != EMPTY_HASH) {
                synchronize_rcu_tasks();
                free_ftrace_hash(free_hash);
        }

        if (new_hash)
                free_ftrace_hash(new_hash);

        return err;
}
EXPORT_SYMBOL_GPL(register_ftrace_direct);

/**
 * unregister_ftrace_direct - Remove calls to custom trampoline
 * previously registered by register_ftrace_direct for @ops object.
 * @ops: The address of the struct ftrace_ops object
 *
 * This is used to remove a direct calls to @addr from the nop locations
 * of the functions registered in @ops (with by ftrace_set_filter_ip
 * function).
 *
 * Returns:
 *  0 on success
 *  -EINVAL - The @ops object was not properly registered.
 */
int unregister_ftrace_direct(struct ftrace_ops *ops, unsigned long addr,
                             bool free_filters)
{
        struct ftrace_hash *hash = ops->func_hash->filter_hash;
        int err;

        if (check_direct_multi(ops))
                return -EINVAL;
        if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
                return -EINVAL;

        mutex_lock(&direct_mutex);
        err = unregister_ftrace_function(ops);
        remove_direct_functions_hash(hash, addr);
        mutex_unlock(&direct_mutex);

        /* cleanup for possible another register call */
        ops->func = NULL;
        ops->trampoline = 0;

        if (free_filters)
                ftrace_free_filter(ops);
        return err;
}
EXPORT_SYMBOL_GPL(unregister_ftrace_direct);

static int
__modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
{
        struct ftrace_hash *hash;
        struct ftrace_func_entry *entry, *iter;
        static struct ftrace_ops tmp_ops = {
                .func           = ftrace_stub,
                .flags          = FTRACE_OPS_FL_STUB,
        };
        int i, size;
        int err;

        lockdep_assert_held_once(&direct_mutex);

        /* Enable the tmp_ops to have the same functions as the direct ops */
        ftrace_ops_init(&tmp_ops);
        tmp_ops.func_hash = ops->func_hash;
        tmp_ops.direct_call = addr;

        err = register_ftrace_function_nolock(&tmp_ops);
        if (err)
                return err;

        /*
         * Now the ftrace_ops_list_func() is called to do the direct callers.
         * We can safely change the direct functions attached to each entry.
         */
        mutex_lock(&ftrace_lock);

        hash = ops->func_hash->filter_hash;
        size = 1 << hash->size_bits;
        for (i = 0; i < size; i++) {
                hlist_for_each_entry(iter, &hash->buckets[i], hlist) {
                        entry = __ftrace_lookup_ip(direct_functions, iter->ip);
                        if (!entry)
                                continue;
                        entry->direct = addr;
                }
        }
        /* Prevent store tearing if a trampoline concurrently accesses the value */
        WRITE_ONCE(ops->direct_call, addr);

        mutex_unlock(&ftrace_lock);

        /* Removing the tmp_ops will add the updated direct callers to the functions */
        unregister_ftrace_function(&tmp_ops);

        return err;
}

/**
 * modify_ftrace_direct_nolock - Modify an existing direct 'multi' call
 * to call something else
 * @ops: The address of the struct ftrace_ops object
 * @addr: The address of the new trampoline to call at @ops functions
 *
 * This is used to unregister currently registered direct caller and
 * register new one @addr on functions registered in @ops object.
 *
 * Note there's window between ftrace_shutdown and ftrace_startup calls
 * where there will be no callbacks called.
 *
 * Caller should already have direct_mutex locked, so we don't lock
 * direct_mutex here.
 *
 * Returns: zero on success. Non zero on error, which includes:
 *  -EINVAL - The @ops object was not properly registered.
 */
int modify_ftrace_direct_nolock(struct ftrace_ops *ops, unsigned long addr)
{
        if (check_direct_multi(ops))
                return -EINVAL;
        if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
                return -EINVAL;

        return __modify_ftrace_direct(ops, addr);
}
EXPORT_SYMBOL_GPL(modify_ftrace_direct_nolock);

/**
 * modify_ftrace_direct - Modify an existing direct 'multi' call
 * to call something else
 * @ops: The address of the struct ftrace_ops object
 * @addr: The address of the new trampoline to call at @ops functions
 *
 * This is used to unregister currently registered direct caller and
 * register new one @addr on functions registered in @ops object.
 *
 * Note there's window between ftrace_shutdown and ftrace_startup calls
 * where there will be no callbacks called.
 *
 * Returns: zero on success. Non zero on error, which includes:
 *  -EINVAL - The @ops object was not properly registered.
 */
int modify_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
{
        int err;

        if (check_direct_multi(ops))
                return -EINVAL;
        if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
                return -EINVAL;

        mutex_lock(&direct_mutex);
        err = __modify_ftrace_direct(ops, addr);
        mutex_unlock(&direct_mutex);
        return err;
}
EXPORT_SYMBOL_GPL(modify_ftrace_direct);
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */

/**
 * ftrace_set_filter_ip - set a function to filter on in ftrace by address
 * @ops: the ops to set the filter with
 * @ip: the address to add to or remove from the filter.
 * @remove: non zero to remove the ip from the filter
 * @reset: non zero to reset all filters before applying this filter.
 *
 * Filters denote which functions should be enabled when tracing is enabled
 * If @ip is NULL, it fails to update filter.
 *
 * This can allocate memory which must be freed before @ops can be freed,
 * either by removing each filtered addr or by using
 * ftrace_free_filter(@ops).
 */
int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip,
                         int remove, int reset)
{
        ftrace_ops_init(ops);
        return ftrace_set_addr(ops, &ip, 1, remove, reset, 1);
}
EXPORT_SYMBOL_GPL(ftrace_set_filter_ip);

/**
 * ftrace_set_filter_ips - set functions to filter on in ftrace by addresses
 * @ops: the ops to set the filter with
 * @ips: the array of addresses to add to or remove from the filter.
 * @cnt: the number of addresses in @ips
 * @remove: non zero to remove ips from the filter
 * @reset: non zero to reset all filters before applying this filter.
 *
 * Filters denote which functions should be enabled when tracing is enabled
 * If @ips array or any ip specified within is NULL , it fails to update filter.
 *
 * This can allocate memory which must be freed before @ops can be freed,
 * either by removing each filtered addr or by using
 * ftrace_free_filter(@ops).
*/
int ftrace_set_filter_ips(struct ftrace_ops *ops, unsigned long *ips,
                          unsigned int cnt, int remove, int reset)
{
        ftrace_ops_init(ops);
        return ftrace_set_addr(ops, ips, cnt, remove, reset, 1);
}
EXPORT_SYMBOL_GPL(ftrace_set_filter_ips);

/**
 * ftrace_ops_set_global_filter - setup ops to use global filters
 * @ops: the ops which will use the global filters
 *
 * ftrace users who need global function trace filtering should call this.
 * It can set the global filter only if ops were not initialized before.
 */
void ftrace_ops_set_global_filter(struct ftrace_ops *ops)
{
        if (ops->flags & FTRACE_OPS_FL_INITIALIZED)
                return;

        ftrace_ops_init(ops);
        ops->func_hash = &global_ops.local_hash;
}
EXPORT_SYMBOL_GPL(ftrace_ops_set_global_filter);

static int
ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
                 int reset, int enable)
{
        return ftrace_set_hash(ops, buf, len, NULL, 0, 0, reset, enable);
}

/**
 * ftrace_set_filter - set a function to filter on in ftrace
 * @ops: the ops to set the filter with
 * @buf: the string that holds the function filter text.
 * @len: the length of the string.
 * @reset: non-zero to reset all filters before applying this filter.
 *
 * Filters denote which functions should be enabled when tracing is enabled.
 * If @buf is NULL and reset is set, all functions will be enabled for tracing.
 *
 * This can allocate memory which must be freed before @ops can be freed,
 * either by removing each filtered addr or by using
 * ftrace_free_filter(@ops).
 */
int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
                       int len, int reset)
{
        ftrace_ops_init(ops);
        return ftrace_set_regex(ops, buf, len, reset, 1);
}
EXPORT_SYMBOL_GPL(ftrace_set_filter);

/**
 * ftrace_set_notrace - set a function to not trace in ftrace
 * @ops: the ops to set the notrace filter with
 * @buf: the string that holds the function notrace text.
 * @len: the length of the string.
 * @reset: non-zero to reset all filters before applying this filter.
 *
 * Notrace Filters denote which functions should not be enabled when tracing
 * is enabled. If @buf is NULL and reset is set, all functions will be enabled
 * for tracing.
 *
 * This can allocate memory which must be freed before @ops can be freed,
 * either by removing each filtered addr or by using
 * ftrace_free_filter(@ops).
 */
int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
                        int len, int reset)
{
        ftrace_ops_init(ops);
        return ftrace_set_regex(ops, buf, len, reset, 0);
}
EXPORT_SYMBOL_GPL(ftrace_set_notrace);
/**
 * ftrace_set_global_filter - set a function to filter on with global tracers
 * @buf: the string that holds the function filter text.
 * @len: the length of the string.
 * @reset: non-zero to reset all filters before applying this filter.
 *
 * Filters denote which functions should be enabled when tracing is enabled.
 * If @buf is NULL and reset is set, all functions will be enabled for tracing.
 */
void ftrace_set_global_filter(unsigned char *buf, int len, int reset)
{
        ftrace_set_regex(&global_ops, buf, len, reset, 1);
}
EXPORT_SYMBOL_GPL(ftrace_set_global_filter);

/**
 * ftrace_set_global_notrace - set a function to not trace with global tracers
 * @buf: the string that holds the function notrace text.
 * @len: the length of the string.
 * @reset: non-zero to reset all filters before applying this filter.
 *
 * Notrace Filters denote which functions should not be enabled when tracing
 * is enabled. If @buf is NULL and reset is set, all functions will be enabled
 * for tracing.
 */
void ftrace_set_global_notrace(unsigned char *buf, int len, int reset)
{
        ftrace_set_regex(&global_ops, buf, len, reset, 0);
}
EXPORT_SYMBOL_GPL(ftrace_set_global_notrace);

/*
 * command line interface to allow users to set filters on boot up.
 */
#define FTRACE_FILTER_SIZE              COMMAND_LINE_SIZE
static char ftrace_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
static char ftrace_filter_buf[FTRACE_FILTER_SIZE] __initdata;

/* Used by function selftest to not test if filter is set */
bool ftrace_filter_param __initdata;

static int __init set_ftrace_notrace(char *str)
{
        ftrace_filter_param = true;
        strscpy(ftrace_notrace_buf, str, FTRACE_FILTER_SIZE);
        return 1;
}
__setup("ftrace_notrace=", set_ftrace_notrace);

static int __init set_ftrace_filter(char *str)
{
        ftrace_filter_param = true;
        strscpy(ftrace_filter_buf, str, FTRACE_FILTER_SIZE);
        return 1;
}
__setup("ftrace_filter=", set_ftrace_filter);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static char ftrace_graph_buf[FTRACE_FILTER_SIZE] __initdata;
static char ftrace_graph_notrace_buf[FTRACE_FILTER_SIZE] __initdata;
static int ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer);

static int __init set_graph_function(char *str)
{
        strscpy(ftrace_graph_buf, str, FTRACE_FILTER_SIZE);
        return 1;
}
__setup("ftrace_graph_filter=", set_graph_function);

static int __init set_graph_notrace_function(char *str)
{
        strscpy(ftrace_graph_notrace_buf, str, FTRACE_FILTER_SIZE);
        return 1;
}
__setup("ftrace_graph_notrace=", set_graph_notrace_function);

static int __init set_graph_max_depth_function(char *str)
{
        if (!str)
                return 0;
        fgraph_max_depth = simple_strtoul(str, NULL, 0);
        return 1;
}
__setup("ftrace_graph_max_depth=", set_graph_max_depth_function);

static void __init set_ftrace_early_graph(char *buf, int enable)
{
        int ret;
        char *func;
        struct ftrace_hash *hash;

        hash = alloc_ftrace_hash(FTRACE_HASH_DEFAULT_BITS);
        if (MEM_FAIL(!hash, "Failed to allocate hash\n"))
                return;

        while (buf) {
                func = strsep(&buf, ",");
                /* we allow only one expression at a time */
                ret = ftrace_graph_set_hash(hash, func);
                if (ret)
                        printk(KERN_DEBUG "ftrace: function %s not "
                                          "traceable\n", func);
        }

        if (enable)
                ftrace_graph_hash = hash;
        else
                ftrace_graph_notrace_hash = hash;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

void __init
ftrace_set_early_filter(struct ftrace_ops *ops, char *buf, int enable)
{
        char *func;

        ftrace_ops_init(ops);

        while (buf) {
                func = strsep(&buf, ",");
                ftrace_set_regex(ops, func, strlen(func), 0, enable);
        }
}

static void __init set_ftrace_early_filters(void)
{
        if (ftrace_filter_buf[0])
                ftrace_set_early_filter(&global_ops, ftrace_filter_buf, 1);
        if (ftrace_notrace_buf[0])
                ftrace_set_early_filter(&global_ops, ftrace_notrace_buf, 0);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        if (ftrace_graph_buf[0])
                set_ftrace_early_graph(ftrace_graph_buf, 1);
        if (ftrace_graph_notrace_buf[0])
                set_ftrace_early_graph(ftrace_graph_notrace_buf, 0);
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
}

int ftrace_regex_release(struct inode *inode, struct file *file)
{
        struct seq_file *m = (struct seq_file *)file->private_data;
        struct ftrace_iterator *iter;
        struct ftrace_hash **orig_hash;
        struct trace_parser *parser;
        int filter_hash;

        if (file->f_mode & FMODE_READ) {
                iter = m->private;
                seq_release(inode, file);
        } else
                iter = file->private_data;

        parser = &iter->parser;
        if (trace_parser_loaded(parser)) {
                int enable = !(iter->flags & FTRACE_ITER_NOTRACE);

                ftrace_process_regex(iter, parser->buffer,
                                     parser->idx, enable);
        }

        trace_parser_put(parser);

        mutex_lock(&iter->ops->func_hash->regex_lock);

        if (file->f_mode & FMODE_WRITE) {
                filter_hash = !!(iter->flags & FTRACE_ITER_FILTER);

                if (filter_hash) {
                        orig_hash = &iter->ops->func_hash->filter_hash;
                        if (iter->tr) {
                                if (list_empty(&iter->tr->mod_trace))
                                        iter->hash->flags &= ~FTRACE_HASH_FL_MOD;
                                else
                                        iter->hash->flags |= FTRACE_HASH_FL_MOD;
                        }
                } else
                        orig_hash = &iter->ops->func_hash->notrace_hash;

                mutex_lock(&ftrace_lock);
                ftrace_hash_move_and_update_ops(iter->ops, orig_hash,
                                                      iter->hash, filter_hash);
                mutex_unlock(&ftrace_lock);
        } else {
                /* For read only, the hash is the ops hash */
                iter->hash = NULL;
        }

        mutex_unlock(&iter->ops->func_hash->regex_lock);
        free_ftrace_hash(iter->hash);
        if (iter->tr)
                trace_array_put(iter->tr);
        kfree(iter);

        return 0;
}

static const struct file_operations ftrace_avail_fops = {
        .open = ftrace_avail_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = seq_release_private,
};

static const struct file_operations ftrace_enabled_fops = {
        .open = ftrace_enabled_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = seq_release_private,
};

static const struct file_operations ftrace_touched_fops = {
        .open = ftrace_touched_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = seq_release_private,
};

static const struct file_operations ftrace_avail_addrs_fops = {
        .open = ftrace_avail_addrs_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = seq_release_private,
};

static const struct file_operations ftrace_filter_fops = {
        .open = ftrace_filter_open,
        .read = seq_read,
        .write = ftrace_filter_write,
        .llseek = tracing_lseek,
        .release = ftrace_regex_release,
};

static const struct file_operations ftrace_notrace_fops = {
        .open = ftrace_notrace_open,
        .read = seq_read,
        .write = ftrace_notrace_write,
        .llseek = tracing_lseek,
        .release = ftrace_regex_release,
};

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

static DEFINE_MUTEX(graph_lock);

struct ftrace_hash __rcu *ftrace_graph_hash = EMPTY_HASH;
struct ftrace_hash __rcu *ftrace_graph_notrace_hash = EMPTY_HASH;

enum graph_filter_type {
        GRAPH_FILTER_NOTRACE    = 0,
        GRAPH_FILTER_FUNCTION,
};

#define FTRACE_GRAPH_EMPTY      ((void *)1)

struct ftrace_graph_data {
        struct ftrace_hash              *hash;
        struct ftrace_func_entry        *entry;
        int                             idx;   /* for hash table iteration */
        enum graph_filter_type          type;
        struct ftrace_hash              *new_hash;
        const struct seq_operations     *seq_ops;
        struct trace_parser             parser;
};

static void *
__g_next(struct seq_file *m, loff_t *pos)
{
        struct ftrace_graph_data *fgd = m->private;
        struct ftrace_func_entry *entry = fgd->entry;
        struct hlist_head *head;
        int i, idx = fgd->idx;

        if (*pos >= fgd->hash->count)
                return NULL;

        if (entry) {
                hlist_for_each_entry_continue(entry, hlist) {
                        fgd->entry = entry;
                        return entry;
                }

                idx++;
        }

        for (i = idx; i < 1 << fgd->hash->size_bits; i++) {
                head = &fgd->hash->buckets[i];
                hlist_for_each_entry(entry, head, hlist) {
                        fgd->entry = entry;
                        fgd->idx = i;
                        return entry;
                }
        }
        return NULL;
}

static void *
g_next(struct seq_file *m, void *v, loff_t *pos)
{
        (*pos)++;
        return __g_next(m, pos);
}

static void *g_start(struct seq_file *m, loff_t *pos)
{
        struct ftrace_graph_data *fgd = m->private;

        mutex_lock(&graph_lock);

        if (fgd->type == GRAPH_FILTER_FUNCTION)
                fgd->hash = rcu_dereference_protected(ftrace_graph_hash,
                                        lockdep_is_held(&graph_lock));
        else
                fgd->hash = rcu_dereference_protected(ftrace_graph_notrace_hash,
                                        lockdep_is_held(&graph_lock));

        /* Nothing, tell g_show to print all functions are enabled */
        if (ftrace_hash_empty(fgd->hash) && !*pos)
                return FTRACE_GRAPH_EMPTY;

        fgd->idx = 0;
        fgd->entry = NULL;
        return __g_next(m, pos);
}

static void g_stop(struct seq_file *m, void *p)
{
        mutex_unlock(&graph_lock);
}

static int g_show(struct seq_file *m, void *v)
{
        struct ftrace_func_entry *entry = v;

        if (!entry)
                return 0;

        if (entry == FTRACE_GRAPH_EMPTY) {
                struct ftrace_graph_data *fgd = m->private;

                if (fgd->type == GRAPH_FILTER_FUNCTION)
                        seq_puts(m, "#### all functions enabled ####\n");
                else
                        seq_puts(m, "#### no functions disabled ####\n");
                return 0;
        }

        seq_printf(m, "%ps\n", (void *)entry->ip);

        return 0;
}

static const struct seq_operations ftrace_graph_seq_ops = {
        .start = g_start,
        .next = g_next,
        .stop = g_stop,
        .show = g_show,
};

static int
__ftrace_graph_open(struct inode *inode, struct file *file,
                    struct ftrace_graph_data *fgd)
{
        int ret;
        struct ftrace_hash *new_hash = NULL;

        ret = security_locked_down(LOCKDOWN_TRACEFS);
        if (ret)
                return ret;

        if (file->f_mode & FMODE_WRITE) {
                const int size_bits = FTRACE_HASH_DEFAULT_BITS;

                if (trace_parser_get_init(&fgd->parser, FTRACE_BUFF_MAX))
                        return -ENOMEM;

                if (file->f_flags & O_TRUNC)
                        new_hash = alloc_ftrace_hash(size_bits);
                else
                        new_hash = alloc_and_copy_ftrace_hash(size_bits,
                                                              fgd->hash);
                if (!new_hash) {
                        ret = -ENOMEM;
                        goto out;
                }
        }

        if (file->f_mode & FMODE_READ) {
                ret = seq_open(file, &ftrace_graph_seq_ops);
                if (!ret) {
                        struct seq_file *m = file->private_data;
                        m->private = fgd;
                } else {
                        /* Failed */
                        free_ftrace_hash(new_hash);
                        new_hash = NULL;
                }
        } else
                file->private_data = fgd;

out:
        if (ret < 0 && file->f_mode & FMODE_WRITE)
                trace_parser_put(&fgd->parser);

        fgd->new_hash = new_hash;

        /*
         * All uses of fgd->hash must be taken with the graph_lock
         * held. The graph_lock is going to be released, so force
         * fgd->hash to be reinitialized when it is taken again.
         */
        fgd->hash = NULL;

        return ret;
}

static int
ftrace_graph_open(struct inode *inode, struct file *file)
{
        struct ftrace_graph_data *fgd;
        int ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        fgd = kmalloc(sizeof(*fgd), GFP_KERNEL);
        if (fgd == NULL)
                return -ENOMEM;

        mutex_lock(&graph_lock);

        fgd->hash = rcu_dereference_protected(ftrace_graph_hash,
                                        lockdep_is_held(&graph_lock));
        fgd->type = GRAPH_FILTER_FUNCTION;
        fgd->seq_ops = &ftrace_graph_seq_ops;

        ret = __ftrace_graph_open(inode, file, fgd);
        if (ret < 0)
                kfree(fgd);

        mutex_unlock(&graph_lock);
        return ret;
}

static int
ftrace_graph_notrace_open(struct inode *inode, struct file *file)
{
        struct ftrace_graph_data *fgd;
        int ret;

        if (unlikely(ftrace_disabled))
                return -ENODEV;

        fgd = kmalloc(sizeof(*fgd), GFP_KERNEL);
        if (fgd == NULL)
                return -ENOMEM;

        mutex_lock(&graph_lock);

        fgd->hash = rcu_dereference_protected(ftrace_graph_notrace_hash,
                                        lockdep_is_held(&graph_lock));
        fgd->type = GRAPH_FILTER_NOTRACE;
        fgd->seq_ops = &ftrace_graph_seq_ops;

        ret = __ftrace_graph_open(inode, file, fgd);
        if (ret < 0)
                kfree(fgd);

        mutex_unlock(&graph_lock);
        return ret;
}

static int
ftrace_graph_release(struct inode *inode, struct file *file)
{
        struct ftrace_graph_data *fgd;
        struct ftrace_hash *old_hash, *new_hash;
        struct trace_parser *parser;
        int ret = 0;

        if (file->f_mode & FMODE_READ) {
                struct seq_file *m = file->private_data;

                fgd = m->private;
                seq_release(inode, file);
        } else {
                fgd = file->private_data;
        }


        if (file->f_mode & FMODE_WRITE) {

                parser = &fgd->parser;

                if (trace_parser_loaded((parser))) {
                        ret = ftrace_graph_set_hash(fgd->new_hash,
                                                    parser->buffer);
                }

                trace_parser_put(parser);

                new_hash = __ftrace_hash_move(fgd->new_hash);
                if (!new_hash) {
                        ret = -ENOMEM;
                        goto out;
                }

                mutex_lock(&graph_lock);

                if (fgd->type == GRAPH_FILTER_FUNCTION) {
                        old_hash = rcu_dereference_protected(ftrace_graph_hash,
                                        lockdep_is_held(&graph_lock));
                        rcu_assign_pointer(ftrace_graph_hash, new_hash);
                } else {
                        old_hash = rcu_dereference_protected(ftrace_graph_notrace_hash,
                                        lockdep_is_held(&graph_lock));
                        rcu_assign_pointer(ftrace_graph_notrace_hash, new_hash);
                }

                mutex_unlock(&graph_lock);

                /*
                 * We need to do a hard force of sched synchronization.
                 * This is because we use preempt_disable() to do RCU, but
                 * the function tracers can be called where RCU is not watching
                 * (like before user_exit()). We can not rely on the RCU
                 * infrastructure to do the synchronization, thus we must do it
                 * ourselves.
                 */
                if (old_hash != EMPTY_HASH)
                        synchronize_rcu_tasks_rude();

                free_ftrace_hash(old_hash);
        }

 out:
        free_ftrace_hash(fgd->new_hash);
        kfree(fgd);

        return ret;
}

static int
ftrace_graph_set_hash(struct ftrace_hash *hash, char *buffer)
{
        struct ftrace_glob func_g;
        struct dyn_ftrace *rec;
        struct ftrace_page *pg;
        struct ftrace_func_entry *entry;
        int fail = 1;
        int not;

        /* decode regex */
        func_g.type = filter_parse_regex(buffer, strlen(buffer),
                                         &func_g.search, &not);

        func_g.len = strlen(func_g.search);

        mutex_lock(&ftrace_lock);

        if (unlikely(ftrace_disabled)) {
                mutex_unlock(&ftrace_lock);
                return -ENODEV;
        }

        do_for_each_ftrace_rec(pg, rec) {

                if (rec->flags & FTRACE_FL_DISABLED)
                        continue;

                if (ftrace_match_record(rec, &func_g, NULL, 0)) {
                        entry = ftrace_lookup_ip(hash, rec->ip);

                        if (!not) {
                                fail = 0;

                                if (entry)
                                        continue;
                                if (add_hash_entry(hash, rec->ip) == NULL)
                                        goto out;
                        } else {
                                if (entry) {
                                        free_hash_entry(hash, entry);
                                        fail = 0;
                                }
                        }
                }
        } while_for_each_ftrace_rec();
out:
        mutex_unlock(&ftrace_lock);

        if (fail)
                return -EINVAL;

        return 0;
}

static ssize_t
ftrace_graph_write(struct file *file, const char __user *ubuf,
                   size_t cnt, loff_t *ppos)
{
        ssize_t read, ret = 0;
        struct ftrace_graph_data *fgd = file->private_data;
        struct trace_parser *parser;

        if (!cnt)
                return 0;

        /* Read mode uses seq functions */
        if (file->f_mode & FMODE_READ) {
                struct seq_file *m = file->private_data;
                fgd = m->private;
        }

        parser = &fgd->parser;

        read = trace_get_user(parser, ubuf, cnt, ppos);

        if (read >= 0 && trace_parser_loaded(parser) &&
            !trace_parser_cont(parser)) {

                ret = ftrace_graph_set_hash(fgd->new_hash,
                                            parser->buffer);
                trace_parser_clear(parser);
        }

        if (!ret)
                ret = read;

        return ret;
}

static const struct file_operations ftrace_graph_fops = {
        .open           = ftrace_graph_open,
        .read           = seq_read,
        .write          = ftrace_graph_write,
        .llseek         = tracing_lseek,
        .release        = ftrace_graph_release,
};

static const struct file_operations ftrace_graph_notrace_fops = {
        .open           = ftrace_graph_notrace_open,
        .read           = seq_read,
        .write          = ftrace_graph_write,
        .llseek         = tracing_lseek,
        .release        = ftrace_graph_release,
};
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

void ftrace_create_filter_files(struct ftrace_ops *ops,
                                struct dentry *parent)
{

        trace_create_file("set_ftrace_filter", TRACE_MODE_WRITE, parent,
                          ops, &ftrace_filter_fops);

        trace_create_file("set_ftrace_notrace", TRACE_MODE_WRITE, parent,
                          ops, &ftrace_notrace_fops);
}

/*
 * The name "destroy_filter_files" is really a misnomer. Although
 * in the future, it may actually delete the files, but this is
 * really intended to make sure the ops passed in are disabled
 * and that when this function returns, the caller is free to
 * free the ops.
 *
 * The "destroy" name is only to match the "create" name that this
 * should be paired with.
 */
void ftrace_destroy_filter_files(struct ftrace_ops *ops)
{
        mutex_lock(&ftrace_lock);
        if (ops->flags & FTRACE_OPS_FL_ENABLED)
                ftrace_shutdown(ops, 0);
        ops->flags |= FTRACE_OPS_FL_DELETED;
        ftrace_free_filter(ops);
        mutex_unlock(&ftrace_lock);
}

static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer)
{

        trace_create_file("available_filter_functions", TRACE_MODE_READ,
                        d_tracer, NULL, &ftrace_avail_fops);

        trace_create_file("available_filter_functions_addrs", TRACE_MODE_READ,
                        d_tracer, NULL, &ftrace_avail_addrs_fops);

        trace_create_file("enabled_functions", TRACE_MODE_READ,
                        d_tracer, NULL, &ftrace_enabled_fops);

        trace_create_file("touched_functions", TRACE_MODE_READ,
                        d_tracer, NULL, &ftrace_touched_fops);

        ftrace_create_filter_files(&global_ops, d_tracer);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        trace_create_file("set_graph_function", TRACE_MODE_WRITE, d_tracer,
                                    NULL,
                                    &ftrace_graph_fops);
        trace_create_file("set_graph_notrace", TRACE_MODE_WRITE, d_tracer,
                                    NULL,
                                    &ftrace_graph_notrace_fops);
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

        return 0;
}

static int ftrace_cmp_ips(const void *a, const void *b)
{
        const unsigned long *ipa = a;
        const unsigned long *ipb = b;

        if (*ipa > *ipb)
                return 1;
        if (*ipa < *ipb)
                return -1;
        return 0;
}

#ifdef CONFIG_FTRACE_SORT_STARTUP_TEST
static void test_is_sorted(unsigned long *start, unsigned long count)
{
        int i;

        for (i = 1; i < count; i++) {
                if (WARN(start[i - 1] > start[i],
                         "[%d] %pS at %lx is not sorted with %pS at %lx\n", i,
                         (void *)start[i - 1], start[i - 1],
                         (void *)start[i], start[i]))
                        break;
        }
        if (i == count)
                pr_info("ftrace section at %px sorted properly\n", start);
}
#else
static void test_is_sorted(unsigned long *start, unsigned long count)
{
}
#endif

static int ftrace_process_locs(struct module *mod,
                               unsigned long *start,
                               unsigned long *end)
{
        struct ftrace_page *pg_unuse = NULL;
        struct ftrace_page *start_pg;
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        unsigned long skipped = 0;
        unsigned long count;
        unsigned long *p;
        unsigned long addr;
        unsigned long flags = 0; /* Shut up gcc */
        int ret = -ENOMEM;

        count = end - start;

        if (!count)
                return 0;

        /*
         * Sorting mcount in vmlinux at build time depend on
         * CONFIG_BUILDTIME_MCOUNT_SORT, while mcount loc in
         * modules can not be sorted at build time.
         */
        if (!IS_ENABLED(CONFIG_BUILDTIME_MCOUNT_SORT) || mod) {
                sort(start, count, sizeof(*start),
                     ftrace_cmp_ips, NULL);
        } else {
                test_is_sorted(start, count);
        }

        start_pg = ftrace_allocate_pages(count);
        if (!start_pg)
                return -ENOMEM;

        mutex_lock(&ftrace_lock);

        /*
         * Core and each module needs their own pages, as
         * modules will free them when they are removed.
         * Force a new page to be allocated for modules.
         */
        if (!mod) {
                WARN_ON(ftrace_pages || ftrace_pages_start);
                /* First initialization */
                ftrace_pages = ftrace_pages_start = start_pg;
        } else {
                if (!ftrace_pages)
                        goto out;

                if (WARN_ON(ftrace_pages->next)) {
                        /* Hmm, we have free pages? */
                        while (ftrace_pages->next)
                                ftrace_pages = ftrace_pages->next;
                }

                ftrace_pages->next = start_pg;
        }

        p = start;
        pg = start_pg;
        while (p < end) {
                unsigned long end_offset;
                addr = ftrace_call_adjust(*p++);
                /*
                 * Some architecture linkers will pad between
                 * the different mcount_loc sections of different
                 * object files to satisfy alignments.
                 * Skip any NULL pointers.
                 */
                if (!addr) {
                        skipped++;
                        continue;
                }

                end_offset = (pg->index+1) * sizeof(pg->records[0]);
                if (end_offset > PAGE_SIZE << pg->order) {
                        /* We should have allocated enough */
                        if (WARN_ON(!pg->next))
                                break;
                        pg = pg->next;
                }

                rec = &pg->records[pg->index++];
                rec->ip = addr;
        }

        if (pg->next) {
                pg_unuse = pg->next;
                pg->next = NULL;
        }

        /* Assign the last page to ftrace_pages */
        ftrace_pages = pg;

        /*
         * We only need to disable interrupts on start up
         * because we are modifying code that an interrupt
         * may execute, and the modification is not atomic.
         * But for modules, nothing runs the code we modify
         * until we are finished with it, and there's no
         * reason to cause large interrupt latencies while we do it.
         */
        if (!mod)
                local_irq_save(flags);
        ftrace_update_code(mod, start_pg);
        if (!mod)
                local_irq_restore(flags);
        ret = 0;
 out:
        mutex_unlock(&ftrace_lock);

        /* We should have used all pages unless we skipped some */
        if (pg_unuse) {
                WARN_ON(!skipped);
                ftrace_free_pages(pg_unuse);
        }
        return ret;
}

struct ftrace_mod_func {
        struct list_head        list;
        char                    *name;
        unsigned long           ip;
        unsigned int            size;
};

struct ftrace_mod_map {
        struct rcu_head         rcu;
        struct list_head        list;
        struct module           *mod;
        unsigned long           start_addr;
        unsigned long           end_addr;
        struct list_head        funcs;
        unsigned int            num_funcs;
};

static int ftrace_get_trampoline_kallsym(unsigned int symnum,
                                         unsigned long *value, char *type,
                                         char *name, char *module_name,
                                         int *exported)
{
        struct ftrace_ops *op;

        list_for_each_entry_rcu(op, &ftrace_ops_trampoline_list, list) {
                if (!op->trampoline || symnum--)
                        continue;
                *value = op->trampoline;
                *type = 't';
                strscpy(name, FTRACE_TRAMPOLINE_SYM, KSYM_NAME_LEN);
                strscpy(module_name, FTRACE_TRAMPOLINE_MOD, MODULE_NAME_LEN);
                *exported = 0;
                return 0;
        }

        return -ERANGE;
}

#if defined(CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS) || defined(CONFIG_MODULES)
/*
 * Check if the current ops references the given ip.
 *
 * If the ops traces all functions, then it was already accounted for.
 * If the ops does not trace the current record function, skip it.
 * If the ops ignores the function via notrace filter, skip it.
 */
static bool
ops_references_ip(struct ftrace_ops *ops, unsigned long ip)
{
        /* If ops isn't enabled, ignore it */
        if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
                return false;

        /* If ops traces all then it includes this function */
        if (ops_traces_mod(ops))
                return true;

        /* The function must be in the filter */
        if (!ftrace_hash_empty(ops->func_hash->filter_hash) &&
            !__ftrace_lookup_ip(ops->func_hash->filter_hash, ip))
                return false;

        /* If in notrace hash, we ignore it too */
        if (ftrace_lookup_ip(ops->func_hash->notrace_hash, ip))
                return false;

        return true;
}
#endif

#ifdef CONFIG_MODULES

#define next_to_ftrace_page(p) container_of(p, struct ftrace_page, next)

static LIST_HEAD(ftrace_mod_maps);

static int referenced_filters(struct dyn_ftrace *rec)
{
        struct ftrace_ops *ops;
        int cnt = 0;

        for (ops = ftrace_ops_list; ops != &ftrace_list_end; ops = ops->next) {
                if (ops_references_ip(ops, rec->ip)) {
                        if (WARN_ON_ONCE(ops->flags & FTRACE_OPS_FL_DIRECT))
                                continue;
                        if (WARN_ON_ONCE(ops->flags & FTRACE_OPS_FL_IPMODIFY))
                                continue;
                        cnt++;
                        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS)
                                rec->flags |= FTRACE_FL_REGS;
                        if (cnt == 1 && ops->trampoline)
                                rec->flags |= FTRACE_FL_TRAMP;
                        else
                                rec->flags &= ~FTRACE_FL_TRAMP;
                }
        }

        return cnt;
}

static void
clear_mod_from_hash(struct ftrace_page *pg, struct ftrace_hash *hash)
{
        struct ftrace_func_entry *entry;
        struct dyn_ftrace *rec;
        int i;

        if (ftrace_hash_empty(hash))
                return;

        for (i = 0; i < pg->index; i++) {
                rec = &pg->records[i];
                entry = __ftrace_lookup_ip(hash, rec->ip);
                /*
                 * Do not allow this rec to match again.
                 * Yeah, it may waste some memory, but will be removed
                 * if/when the hash is modified again.
                 */
                if (entry)
                        entry->ip = 0;
        }
}

/* Clear any records from hashes */
static void clear_mod_from_hashes(struct ftrace_page *pg)
{
        struct trace_array *tr;

        mutex_lock(&trace_types_lock);
        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
                if (!tr->ops || !tr->ops->func_hash)
                        continue;
                mutex_lock(&tr->ops->func_hash->regex_lock);
                clear_mod_from_hash(pg, tr->ops->func_hash->filter_hash);
                clear_mod_from_hash(pg, tr->ops->func_hash->notrace_hash);
                mutex_unlock(&tr->ops->func_hash->regex_lock);
        }
        mutex_unlock(&trace_types_lock);
}

static void ftrace_free_mod_map(struct rcu_head *rcu)
{
        struct ftrace_mod_map *mod_map = container_of(rcu, struct ftrace_mod_map, rcu);
        struct ftrace_mod_func *mod_func;
        struct ftrace_mod_func *n;

        /* All the contents of mod_map are now not visible to readers */
        list_for_each_entry_safe(mod_func, n, &mod_map->funcs, list) {
                kfree(mod_func->name);
                list_del(&mod_func->list);
                kfree(mod_func);
        }

        kfree(mod_map);
}

void ftrace_release_mod(struct module *mod)
{
        struct ftrace_mod_map *mod_map;
        struct ftrace_mod_map *n;
        struct dyn_ftrace *rec;
        struct ftrace_page **last_pg;
        struct ftrace_page *tmp_page = NULL;
        struct ftrace_page *pg;

        mutex_lock(&ftrace_lock);

        if (ftrace_disabled)
                goto out_unlock;

        list_for_each_entry_safe(mod_map, n, &ftrace_mod_maps, list) {
                if (mod_map->mod == mod) {
                        list_del_rcu(&mod_map->list);
                        call_rcu(&mod_map->rcu, ftrace_free_mod_map);
                        break;
                }
        }

        /*
         * Each module has its own ftrace_pages, remove
         * them from the list.
         */
        last_pg = &ftrace_pages_start;
        for (pg = ftrace_pages_start; pg; pg = *last_pg) {
                rec = &pg->records[0];
                if (within_module(rec->ip, mod)) {
                        /*
                         * As core pages are first, the first
                         * page should never be a module page.
                         */
                        if (WARN_ON(pg == ftrace_pages_start))
                                goto out_unlock;

                        /* Check if we are deleting the last page */
                        if (pg == ftrace_pages)
                                ftrace_pages = next_to_ftrace_page(last_pg);

                        ftrace_update_tot_cnt -= pg->index;
                        *last_pg = pg->next;

                        pg->next = tmp_page;
                        tmp_page = pg;
                } else
                        last_pg = &pg->next;
        }
 out_unlock:
        mutex_unlock(&ftrace_lock);

        for (pg = tmp_page; pg; pg = tmp_page) {

                /* Needs to be called outside of ftrace_lock */
                clear_mod_from_hashes(pg);

                if (pg->records) {
                        free_pages((unsigned long)pg->records, pg->order);
                        ftrace_number_of_pages -= 1 << pg->order;
                }
                tmp_page = pg->next;
                kfree(pg);
                ftrace_number_of_groups--;
        }
}

void ftrace_module_enable(struct module *mod)
{
        struct dyn_ftrace *rec;
        struct ftrace_page *pg;

        mutex_lock(&ftrace_lock);

        if (ftrace_disabled)
                goto out_unlock;

        /*
         * If the tracing is enabled, go ahead and enable the record.
         *
         * The reason not to enable the record immediately is the
         * inherent check of ftrace_make_nop/ftrace_make_call for
         * correct previous instructions.  Making first the NOP
         * conversion puts the module to the correct state, thus
         * passing the ftrace_make_call check.
         *
         * We also delay this to after the module code already set the
         * text to read-only, as we now need to set it back to read-write
         * so that we can modify the text.
         */
        if (ftrace_start_up)
                ftrace_arch_code_modify_prepare();

        do_for_each_ftrace_rec(pg, rec) {
                int cnt;
                /*
                 * do_for_each_ftrace_rec() is a double loop.
                 * module text shares the pg. If a record is
                 * not part of this module, then skip this pg,
                 * which the "break" will do.
                 */
                if (!within_module(rec->ip, mod))
                        break;

                /* Weak functions should still be ignored */
                if (!test_for_valid_rec(rec)) {
                        /* Clear all other flags. Should not be enabled anyway */
                        rec->flags = FTRACE_FL_DISABLED;
                        continue;
                }

                cnt = 0;

                /*
                 * When adding a module, we need to check if tracers are
                 * currently enabled and if they are, and can trace this record,
                 * we need to enable the module functions as well as update the
                 * reference counts for those function records.
                 */
                if (ftrace_start_up)
                        cnt += referenced_filters(rec);

                rec->flags &= ~FTRACE_FL_DISABLED;
                rec->flags += cnt;

                if (ftrace_start_up && cnt) {
                        int failed = __ftrace_replace_code(rec, 1);
                        if (failed) {
                                ftrace_bug(failed, rec);
                                goto out_loop;
                        }
                }

        } while_for_each_ftrace_rec();

 out_loop:
        if (ftrace_start_up)
                ftrace_arch_code_modify_post_process();

 out_unlock:
        mutex_unlock(&ftrace_lock);

        process_cached_mods(mod->name);
}

void ftrace_module_init(struct module *mod)
{
        int ret;

        if (ftrace_disabled || !mod->num_ftrace_callsites)
                return;

        ret = ftrace_process_locs(mod, mod->ftrace_callsites,
                                  mod->ftrace_callsites + mod->num_ftrace_callsites);
        if (ret)
                pr_warn("ftrace: failed to allocate entries for module '%s' functions\n",
                        mod->name);
}

static void save_ftrace_mod_rec(struct ftrace_mod_map *mod_map,
                                struct dyn_ftrace *rec)
{
        struct ftrace_mod_func *mod_func;
        unsigned long symsize;
        unsigned long offset;
        char str[KSYM_SYMBOL_LEN];
        char *modname;
        const char *ret;

        ret = kallsyms_lookup(rec->ip, &symsize, &offset, &modname, str);
        if (!ret)
                return;

        mod_func = kmalloc(sizeof(*mod_func), GFP_KERNEL);
        if (!mod_func)
                return;

        mod_func->name = kstrdup(str, GFP_KERNEL);
        if (!mod_func->name) {
                kfree(mod_func);
                return;
        }

        mod_func->ip = rec->ip - offset;
        mod_func->size = symsize;

        mod_map->num_funcs++;

        list_add_rcu(&mod_func->list, &mod_map->funcs);
}

static struct ftrace_mod_map *
allocate_ftrace_mod_map(struct module *mod,
                        unsigned long start, unsigned long end)
{
        struct ftrace_mod_map *mod_map;

        mod_map = kmalloc(sizeof(*mod_map), GFP_KERNEL);
        if (!mod_map)
                return NULL;

        mod_map->mod = mod;
        mod_map->start_addr = start;
        mod_map->end_addr = end;
        mod_map->num_funcs = 0;

        INIT_LIST_HEAD_RCU(&mod_map->funcs);

        list_add_rcu(&mod_map->list, &ftrace_mod_maps);

        return mod_map;
}

static const char *
ftrace_func_address_lookup(struct ftrace_mod_map *mod_map,
                           unsigned long addr, unsigned long *size,
                           unsigned long *off, char *sym)
{
        struct ftrace_mod_func *found_func =  NULL;
        struct ftrace_mod_func *mod_func;

        list_for_each_entry_rcu(mod_func, &mod_map->funcs, list) {
                if (addr >= mod_func->ip &&
                    addr < mod_func->ip + mod_func->size) {
                        found_func = mod_func;
                        break;
                }
        }

        if (found_func) {
                if (size)
                        *size = found_func->size;
                if (off)
                        *off = addr - found_func->ip;
                if (sym)
                        strscpy(sym, found_func->name, KSYM_NAME_LEN);

                return found_func->name;
        }

        return NULL;
}

const char *
ftrace_mod_address_lookup(unsigned long addr, unsigned long *size,
                   unsigned long *off, char **modname, char *sym)
{
        struct ftrace_mod_map *mod_map;
        const char *ret = NULL;

        /* mod_map is freed via call_rcu() */
        preempt_disable();
        list_for_each_entry_rcu(mod_map, &ftrace_mod_maps, list) {
                ret = ftrace_func_address_lookup(mod_map, addr, size, off, sym);
                if (ret) {
                        if (modname)
                                *modname = mod_map->mod->name;
                        break;
                }
        }
        preempt_enable();

        return ret;
}

int ftrace_mod_get_kallsym(unsigned int symnum, unsigned long *value,
                           char *type, char *name,
                           char *module_name, int *exported)
{
        struct ftrace_mod_map *mod_map;
        struct ftrace_mod_func *mod_func;
        int ret;

        preempt_disable();
        list_for_each_entry_rcu(mod_map, &ftrace_mod_maps, list) {

                if (symnum >= mod_map->num_funcs) {
                        symnum -= mod_map->num_funcs;
                        continue;
                }

                list_for_each_entry_rcu(mod_func, &mod_map->funcs, list) {
                        if (symnum > 1) {
                                symnum--;
                                continue;
                        }

                        *value = mod_func->ip;
                        *type = 'T';
                        strscpy(name, mod_func->name, KSYM_NAME_LEN);
                        strscpy(module_name, mod_map->mod->name, MODULE_NAME_LEN);
                        *exported = 1;
                        preempt_enable();
                        return 0;
                }
                WARN_ON(1);
                break;
        }
        ret = ftrace_get_trampoline_kallsym(symnum, value, type, name,
                                            module_name, exported);
        preempt_enable();
        return ret;
}

#else
static void save_ftrace_mod_rec(struct ftrace_mod_map *mod_map,
                                struct dyn_ftrace *rec) { }
static inline struct ftrace_mod_map *
allocate_ftrace_mod_map(struct module *mod,
                        unsigned long start, unsigned long end)
{
        return NULL;
}
int ftrace_mod_get_kallsym(unsigned int symnum, unsigned long *value,
                           char *type, char *name, char *module_name,
                           int *exported)
{
        int ret;

        preempt_disable();
        ret = ftrace_get_trampoline_kallsym(symnum, value, type, name,
                                            module_name, exported);
        preempt_enable();
        return ret;
}
#endif /* CONFIG_MODULES */

struct ftrace_init_func {
        struct list_head list;
        unsigned long ip;
};

/* Clear any init ips from hashes */
static void
clear_func_from_hash(struct ftrace_init_func *func, struct ftrace_hash *hash)
{
        struct ftrace_func_entry *entry;

        entry = ftrace_lookup_ip(hash, func->ip);
        /*
         * Do not allow this rec to match again.
         * Yeah, it may waste some memory, but will be removed
         * if/when the hash is modified again.
         */
        if (entry)
                entry->ip = 0;
}

static void
clear_func_from_hashes(struct ftrace_init_func *func)
{
        struct trace_array *tr;

        mutex_lock(&trace_types_lock);
        list_for_each_entry(tr, &ftrace_trace_arrays, list) {
                if (!tr->ops || !tr->ops->func_hash)
                        continue;
                mutex_lock(&tr->ops->func_hash->regex_lock);
                clear_func_from_hash(func, tr->ops->func_hash->filter_hash);
                clear_func_from_hash(func, tr->ops->func_hash->notrace_hash);
                mutex_unlock(&tr->ops->func_hash->regex_lock);
        }
        mutex_unlock(&trace_types_lock);
}

static void add_to_clear_hash_list(struct list_head *clear_list,
                                   struct dyn_ftrace *rec)
{
        struct ftrace_init_func *func;

        func = kmalloc(sizeof(*func), GFP_KERNEL);
        if (!func) {
                MEM_FAIL(1, "alloc failure, ftrace filter could be stale\n");
                return;
        }

        func->ip = rec->ip;
        list_add(&func->list, clear_list);
}

void ftrace_free_mem(struct module *mod, void *start_ptr, void *end_ptr)
{
        unsigned long start = (unsigned long)(start_ptr);
        unsigned long end = (unsigned long)(end_ptr);
        struct ftrace_page **last_pg = &ftrace_pages_start;
        struct ftrace_page *pg;
        struct dyn_ftrace *rec;
        struct dyn_ftrace key;
        struct ftrace_mod_map *mod_map = NULL;
        struct ftrace_init_func *func, *func_next;
        LIST_HEAD(clear_hash);

        key.ip = start;
        key.flags = end;        /* overload flags, as it is unsigned long */

        mutex_lock(&ftrace_lock);

        /*
         * If we are freeing module init memory, then check if
         * any tracer is active. If so, we need to save a mapping of
         * the module functions being freed with the address.
         */
        if (mod && ftrace_ops_list != &ftrace_list_end)
                mod_map = allocate_ftrace_mod_map(mod, start, end);

        for (pg = ftrace_pages_start; pg; last_pg = &pg->next, pg = *last_pg) {
                if (end < pg->records[0].ip ||
                    start >= (pg->records[pg->index - 1].ip + MCOUNT_INSN_SIZE))
                        continue;
 again:
                rec = bsearch(&key, pg->records, pg->index,
                              sizeof(struct dyn_ftrace),
                              ftrace_cmp_recs);
                if (!rec)
                        continue;

                /* rec will be cleared from hashes after ftrace_lock unlock */
                add_to_clear_hash_list(&clear_hash, rec);

                if (mod_map)
                        save_ftrace_mod_rec(mod_map, rec);

                pg->index--;
                ftrace_update_tot_cnt--;
                if (!pg->index) {
                        *last_pg = pg->next;
                        if (pg->records) {
                                free_pages((unsigned long)pg->records, pg->order);
                                ftrace_number_of_pages -= 1 << pg->order;
                        }
                        ftrace_number_of_groups--;
                        kfree(pg);
                        pg = container_of(last_pg, struct ftrace_page, next);
                        if (!(*last_pg))
                                ftrace_pages = pg;
                        continue;
                }
                memmove(rec, rec + 1,
                        (pg->index - (rec - pg->records)) * sizeof(*rec));
                /* More than one function may be in this block */
                goto again;
        }
        mutex_unlock(&ftrace_lock);

        list_for_each_entry_safe(func, func_next, &clear_hash, list) {
                clear_func_from_hashes(func);
                kfree(func);
        }
}

void __init ftrace_free_init_mem(void)
{
        void *start = (void *)(&__init_begin);
        void *end = (void *)(&__init_end);

        ftrace_boot_snapshot();

        ftrace_free_mem(NULL, start, end);
}

int __init __weak ftrace_dyn_arch_init(void)
{
        return 0;
}

void __init ftrace_init(void)
{
        extern unsigned long __start_mcount_loc[];
        extern unsigned long __stop_mcount_loc[];
        unsigned long count, flags;
        int ret;

        local_irq_save(flags);
        ret = ftrace_dyn_arch_init();
        local_irq_restore(flags);
        if (ret)
                goto failed;

        count = __stop_mcount_loc - __start_mcount_loc;
        if (!count) {
                pr_info("ftrace: No functions to be traced?\n");
                goto failed;
        }

        pr_info("ftrace: allocating %ld entries in %ld pages\n",
                count, DIV_ROUND_UP(count, ENTRIES_PER_PAGE));

        ret = ftrace_process_locs(NULL,
                                  __start_mcount_loc,
                                  __stop_mcount_loc);
        if (ret) {
                pr_warn("ftrace: failed to allocate entries for functions\n");
                goto failed;
        }

        pr_info("ftrace: allocated %ld pages with %ld groups\n",
                ftrace_number_of_pages, ftrace_number_of_groups);

        last_ftrace_enabled = ftrace_enabled = 1;

        set_ftrace_early_filters();

        return;
 failed:
        ftrace_disabled = 1;
}

/* Do nothing if arch does not support this */
void __weak arch_ftrace_update_trampoline(struct ftrace_ops *ops)
{
}

static void ftrace_update_trampoline(struct ftrace_ops *ops)
{
        unsigned long trampoline = ops->trampoline;

        arch_ftrace_update_trampoline(ops);
        if (ops->trampoline && ops->trampoline != trampoline &&
            (ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP)) {
                /* Add to kallsyms before the perf events */
                ftrace_add_trampoline_to_kallsyms(ops);
                perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL,
                                   ops->trampoline, ops->trampoline_size, false,
                                   FTRACE_TRAMPOLINE_SYM);
                /*
                 * Record the perf text poke event after the ksymbol register
                 * event.
                 */
                perf_event_text_poke((void *)ops->trampoline, NULL, 0,
                                     (void *)ops->trampoline,
                                     ops->trampoline_size);
        }
}

void ftrace_init_trace_array(struct trace_array *tr)
{
        INIT_LIST_HEAD(&tr->func_probes);
        INIT_LIST_HEAD(&tr->mod_trace);
        INIT_LIST_HEAD(&tr->mod_notrace);
}
#else

struct ftrace_ops global_ops = {
        .func                   = ftrace_stub,
        .flags                  = FTRACE_OPS_FL_INITIALIZED |
                                  FTRACE_OPS_FL_PID,
};

static int __init ftrace_nodyn_init(void)
{
        ftrace_enabled = 1;
        return 0;
}
core_initcall(ftrace_nodyn_init);

static inline int ftrace_init_dyn_tracefs(struct dentry *d_tracer) { return 0; }
static inline void ftrace_startup_all(int command) { }

static void ftrace_update_trampoline(struct ftrace_ops *ops)
{
}

#endif /* CONFIG_DYNAMIC_FTRACE */

__init void ftrace_init_global_array_ops(struct trace_array *tr)
{
        tr->ops = &global_ops;
        tr->ops->private = tr;
        ftrace_init_trace_array(tr);
}

void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func)
{
        /* If we filter on pids, update to use the pid function */
        if (tr->flags & TRACE_ARRAY_FL_GLOBAL) {
                if (WARN_ON(tr->ops->func != ftrace_stub))
                        printk("ftrace ops had %pS for function\n",
                               tr->ops->func);
        }
        tr->ops->func = func;
        tr->ops->private = tr;
}

void ftrace_reset_array_ops(struct trace_array *tr)
{
        tr->ops->func = ftrace_stub;
}

static nokprobe_inline void
__ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
                       struct ftrace_ops *ignored, struct ftrace_regs *fregs)
{
        struct pt_regs *regs = ftrace_get_regs(fregs);
        struct ftrace_ops *op;
        int bit;

        /*
         * The ftrace_test_and_set_recursion() will disable preemption,
         * which is required since some of the ops may be dynamically
         * allocated, they must be freed after a synchronize_rcu().
         */
        bit = trace_test_and_set_recursion(ip, parent_ip, TRACE_LIST_START);
        if (bit < 0)
                return;

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                /* Stub functions don't need to be called nor tested */
                if (op->flags & FTRACE_OPS_FL_STUB)
                        continue;
                /*
                 * Check the following for each ops before calling their func:
                 *  if RCU flag is set, then rcu_is_watching() must be true
                 *  Otherwise test if the ip matches the ops filter
                 *
                 * If any of the above fails then the op->func() is not executed.
                 */
                if ((!(op->flags & FTRACE_OPS_FL_RCU) || rcu_is_watching()) &&
                    ftrace_ops_test(op, ip, regs)) {
                        if (FTRACE_WARN_ON(!op->func)) {
                                pr_warn("op=%p %pS\n", op, op);
                                goto out;
                        }
                        op->func(ip, parent_ip, op, fregs);
                }
        } while_for_each_ftrace_op(op);
out:
        trace_clear_recursion(bit);
}

/*
 * Some archs only support passing ip and parent_ip. Even though
 * the list function ignores the op parameter, we do not want any
 * C side effects, where a function is called without the caller
 * sending a third parameter.
 * Archs are to support both the regs and ftrace_ops at the same time.
 * If they support ftrace_ops, it is assumed they support regs.
 * If call backs want to use regs, they must either check for regs
 * being NULL, or CONFIG_DYNAMIC_FTRACE_WITH_REGS.
 * Note, CONFIG_DYNAMIC_FTRACE_WITH_REGS expects a full regs to be saved.
 * An architecture can pass partial regs with ftrace_ops and still
 * set the ARCH_SUPPORTS_FTRACE_OPS.
 *
 * In vmlinux.lds.h, ftrace_ops_list_func() is defined to be
 * arch_ftrace_ops_list_func.
 */
#if ARCH_SUPPORTS_FTRACE_OPS
void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
                               struct ftrace_ops *op, struct ftrace_regs *fregs)
{
        __ftrace_ops_list_func(ip, parent_ip, NULL, fregs);
}
#else
void arch_ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip)
{
        __ftrace_ops_list_func(ip, parent_ip, NULL, NULL);
}
#endif
NOKPROBE_SYMBOL(arch_ftrace_ops_list_func);

/*
 * If there's only one function registered but it does not support
 * recursion, needs RCU protection, then this function will be called
 * by the mcount trampoline.
 */
static void ftrace_ops_assist_func(unsigned long ip, unsigned long parent_ip,
                                   struct ftrace_ops *op, struct ftrace_regs *fregs)
{
        int bit;

        bit = trace_test_and_set_recursion(ip, parent_ip, TRACE_LIST_START);
        if (bit < 0)
                return;

        if (!(op->flags & FTRACE_OPS_FL_RCU) || rcu_is_watching())
                op->func(ip, parent_ip, op, fregs);

        trace_clear_recursion(bit);
}
NOKPROBE_SYMBOL(ftrace_ops_assist_func);

/**
 * ftrace_ops_get_func - get the function a trampoline should call
 * @ops: the ops to get the function for
 *
 * Normally the mcount trampoline will call the ops->func, but there
 * are times that it should not. For example, if the ops does not
 * have its own recursion protection, then it should call the
 * ftrace_ops_assist_func() instead.
 *
 * Returns: the function that the trampoline should call for @ops.
 */
ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops)
{
        /*
         * If the function does not handle recursion or needs to be RCU safe,
         * then we need to call the assist handler.
         */
        if (ops->flags & (FTRACE_OPS_FL_RECURSION |
                          FTRACE_OPS_FL_RCU))
                return ftrace_ops_assist_func;

        return ops->func;
}

static void
ftrace_filter_pid_sched_switch_probe(void *data, bool preempt,
                                     struct task_struct *prev,
                                     struct task_struct *next,
                                     unsigned int prev_state)
{
        struct trace_array *tr = data;
        struct trace_pid_list *pid_list;
        struct trace_pid_list *no_pid_list;

        pid_list = rcu_dereference_sched(tr->function_pids);
        no_pid_list = rcu_dereference_sched(tr->function_no_pids);

        if (trace_ignore_this_task(pid_list, no_pid_list, next))
                this_cpu_write(tr->array_buffer.data->ftrace_ignore_pid,
                               FTRACE_PID_IGNORE);
        else
                this_cpu_write(tr->array_buffer.data->ftrace_ignore_pid,
                               next->pid);
}

static void
ftrace_pid_follow_sched_process_fork(void *data,
                                     struct task_struct *self,
                                     struct task_struct *task)
{
        struct trace_pid_list *pid_list;
        struct trace_array *tr = data;

        pid_list = rcu_dereference_sched(tr->function_pids);
        trace_filter_add_remove_task(pid_list, self, task);

        pid_list = rcu_dereference_sched(tr->function_no_pids);
        trace_filter_add_remove_task(pid_list, self, task);
}

static void
ftrace_pid_follow_sched_process_exit(void *data, struct task_struct *task)
{
        struct trace_pid_list *pid_list;
        struct trace_array *tr = data;

        pid_list = rcu_dereference_sched(tr->function_pids);
        trace_filter_add_remove_task(pid_list, NULL, task);

        pid_list = rcu_dereference_sched(tr->function_no_pids);
        trace_filter_add_remove_task(pid_list, NULL, task);
}

void ftrace_pid_follow_fork(struct trace_array *tr, bool enable)
{
        if (enable) {
                register_trace_sched_process_fork(ftrace_pid_follow_sched_process_fork,
                                                  tr);
                register_trace_sched_process_free(ftrace_pid_follow_sched_process_exit,
                                                  tr);
        } else {
                unregister_trace_sched_process_fork(ftrace_pid_follow_sched_process_fork,
                                                    tr);
                unregister_trace_sched_process_free(ftrace_pid_follow_sched_process_exit,
                                                    tr);
        }
}

static void clear_ftrace_pids(struct trace_array *tr, int type)
{
        struct trace_pid_list *pid_list;
        struct trace_pid_list *no_pid_list;
        int cpu;

        pid_list = rcu_dereference_protected(tr->function_pids,
                                             lockdep_is_held(&ftrace_lock));
        no_pid_list = rcu_dereference_protected(tr->function_no_pids,
                                                lockdep_is_held(&ftrace_lock));

        /* Make sure there's something to do */
        if (!pid_type_enabled(type, pid_list, no_pid_list))
                return;

        /* See if the pids still need to be checked after this */
        if (!still_need_pid_events(type, pid_list, no_pid_list)) {
                unregister_trace_sched_switch(ftrace_filter_pid_sched_switch_probe, tr);
                for_each_possible_cpu(cpu)
                        per_cpu_ptr(tr->array_buffer.data, cpu)->ftrace_ignore_pid = FTRACE_PID_TRACE;
        }

        if (type & TRACE_PIDS)
                rcu_assign_pointer(tr->function_pids, NULL);

        if (type & TRACE_NO_PIDS)
                rcu_assign_pointer(tr->function_no_pids, NULL);

        /* Wait till all users are no longer using pid filtering */
        synchronize_rcu();

        if ((type & TRACE_PIDS) && pid_list)
                trace_pid_list_free(pid_list);

        if ((type & TRACE_NO_PIDS) && no_pid_list)
                trace_pid_list_free(no_pid_list);
}

void ftrace_clear_pids(struct trace_array *tr)
{
        mutex_lock(&ftrace_lock);

        clear_ftrace_pids(tr, TRACE_PIDS | TRACE_NO_PIDS);

        mutex_unlock(&ftrace_lock);
}

static void ftrace_pid_reset(struct trace_array *tr, int type)
{
        mutex_lock(&ftrace_lock);
        clear_ftrace_pids(tr, type);

        ftrace_update_pid_func();
        ftrace_startup_all(0);

        mutex_unlock(&ftrace_lock);
}

/* Greater than any max PID */
#define FTRACE_NO_PIDS          (void *)(PID_MAX_LIMIT + 1)

static void *fpid_start(struct seq_file *m, loff_t *pos)
        __acquires(RCU)
{
        struct trace_pid_list *pid_list;
        struct trace_array *tr = m->private;

        mutex_lock(&ftrace_lock);
        rcu_read_lock_sched();

        pid_list = rcu_dereference_sched(tr->function_pids);

        if (!pid_list)
                return !(*pos) ? FTRACE_NO_PIDS : NULL;

        return trace_pid_start(pid_list, pos);
}

static void *fpid_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct trace_array *tr = m->private;
        struct trace_pid_list *pid_list = rcu_dereference_sched(tr->function_pids);

        if (v == FTRACE_NO_PIDS) {
                (*pos)++;
                return NULL;
        }
        return trace_pid_next(pid_list, v, pos);
}

static void fpid_stop(struct seq_file *m, void *p)
        __releases(RCU)
{
        rcu_read_unlock_sched();
        mutex_unlock(&ftrace_lock);
}

static int fpid_show(struct seq_file *m, void *v)
{
        if (v == FTRACE_NO_PIDS) {
                seq_puts(m, "no pid\n");
                return 0;
        }

        return trace_pid_show(m, v);
}

static const struct seq_operations ftrace_pid_sops = {
        .start = fpid_start,
        .next = fpid_next,
        .stop = fpid_stop,
        .show = fpid_show,
};

static void *fnpid_start(struct seq_file *m, loff_t *pos)
        __acquires(RCU)
{
        struct trace_pid_list *pid_list;
        struct trace_array *tr = m->private;

        mutex_lock(&ftrace_lock);
        rcu_read_lock_sched();

        pid_list = rcu_dereference_sched(tr->function_no_pids);

        if (!pid_list)
                return !(*pos) ? FTRACE_NO_PIDS : NULL;

        return trace_pid_start(pid_list, pos);
}

static void *fnpid_next(struct seq_file *m, void *v, loff_t *pos)
{
        struct trace_array *tr = m->private;
        struct trace_pid_list *pid_list = rcu_dereference_sched(tr->function_no_pids);

        if (v == FTRACE_NO_PIDS) {
                (*pos)++;
                return NULL;
        }
        return trace_pid_next(pid_list, v, pos);
}

static const struct seq_operations ftrace_no_pid_sops = {
        .start = fnpid_start,
        .next = fnpid_next,
        .stop = fpid_stop,
        .show = fpid_show,
};

static int pid_open(struct inode *inode, struct file *file, int type)
{
        const struct seq_operations *seq_ops;
        struct trace_array *tr = inode->i_private;
        struct seq_file *m;
        int ret = 0;

        ret = tracing_check_open_get_tr(tr);
        if (ret)
                return ret;

        if ((file->f_mode & FMODE_WRITE) &&
            (file->f_flags & O_TRUNC))
                ftrace_pid_reset(tr, type);

        switch (type) {
        case TRACE_PIDS:
                seq_ops = &ftrace_pid_sops;
                break;
        case TRACE_NO_PIDS:
                seq_ops = &ftrace_no_pid_sops;
                break;
        default:
                trace_array_put(tr);
                WARN_ON_ONCE(1);
                return -EINVAL;
        }

        ret = seq_open(file, seq_ops);
        if (ret < 0) {
                trace_array_put(tr);
        } else {
                m = file->private_data;
                /* copy tr over to seq ops */
                m->private = tr;
        }

        return ret;
}

static int
ftrace_pid_open(struct inode *inode, struct file *file)
{
        return pid_open(inode, file, TRACE_PIDS);
}

static int
ftrace_no_pid_open(struct inode *inode, struct file *file)
{
        return pid_open(inode, file, TRACE_NO_PIDS);
}

static void ignore_task_cpu(void *data)
{
        struct trace_array *tr = data;
        struct trace_pid_list *pid_list;
        struct trace_pid_list *no_pid_list;

        /*
         * This function is called by on_each_cpu() while the
         * event_mutex is held.
         */
        pid_list = rcu_dereference_protected(tr->function_pids,
                                             mutex_is_locked(&ftrace_lock));
        no_pid_list = rcu_dereference_protected(tr->function_no_pids,
                                                mutex_is_locked(&ftrace_lock));

        if (trace_ignore_this_task(pid_list, no_pid_list, current))
                this_cpu_write(tr->array_buffer.data->ftrace_ignore_pid,
                               FTRACE_PID_IGNORE);
        else
                this_cpu_write(tr->array_buffer.data->ftrace_ignore_pid,
                               current->pid);
}

static ssize_t
pid_write(struct file *filp, const char __user *ubuf,
          size_t cnt, loff_t *ppos, int type)
{
        struct seq_file *m = filp->private_data;
        struct trace_array *tr = m->private;
        struct trace_pid_list *filtered_pids;
        struct trace_pid_list *other_pids;
        struct trace_pid_list *pid_list;
        ssize_t ret;

        if (!cnt)
                return 0;

        mutex_lock(&ftrace_lock);

        switch (type) {
        case TRACE_PIDS:
                filtered_pids = rcu_dereference_protected(tr->function_pids,
                                             lockdep_is_held(&ftrace_lock));
                other_pids = rcu_dereference_protected(tr->function_no_pids,
                                             lockdep_is_held(&ftrace_lock));
                break;
        case TRACE_NO_PIDS:
                filtered_pids = rcu_dereference_protected(tr->function_no_pids,
                                             lockdep_is_held(&ftrace_lock));
                other_pids = rcu_dereference_protected(tr->function_pids,
                                             lockdep_is_held(&ftrace_lock));
                break;
        default:
                ret = -EINVAL;
                WARN_ON_ONCE(1);
                goto out;
        }

        ret = trace_pid_write(filtered_pids, &pid_list, ubuf, cnt);
        if (ret < 0)
                goto out;

        switch (type) {
        case TRACE_PIDS:
                rcu_assign_pointer(tr->function_pids, pid_list);
                break;
        case TRACE_NO_PIDS:
                rcu_assign_pointer(tr->function_no_pids, pid_list);
                break;
        }


        if (filtered_pids) {
                synchronize_rcu();
                trace_pid_list_free(filtered_pids);
        } else if (pid_list && !other_pids) {
                /* Register a probe to set whether to ignore the tracing of a task */
                register_trace_sched_switch(ftrace_filter_pid_sched_switch_probe, tr);
        }

        /*
         * Ignoring of pids is done at task switch. But we have to
         * check for those tasks that are currently running.
         * Always do this in case a pid was appended or removed.
         */
        on_each_cpu(ignore_task_cpu, tr, 1);

        ftrace_update_pid_func();
        ftrace_startup_all(0);
 out:
        mutex_unlock(&ftrace_lock);

        if (ret > 0)
                *ppos += ret;

        return ret;
}

static ssize_t
ftrace_pid_write(struct file *filp, const char __user *ubuf,
                 size_t cnt, loff_t *ppos)
{
        return pid_write(filp, ubuf, cnt, ppos, TRACE_PIDS);
}

static ssize_t
ftrace_no_pid_write(struct file *filp, const char __user *ubuf,
                    size_t cnt, loff_t *ppos)
{
        return pid_write(filp, ubuf, cnt, ppos, TRACE_NO_PIDS);
}

static int
ftrace_pid_release(struct inode *inode, struct file *file)
{
        struct trace_array *tr = inode->i_private;

        trace_array_put(tr);

        return seq_release(inode, file);
}

static const struct file_operations ftrace_pid_fops = {
        .open           = ftrace_pid_open,
        .write          = ftrace_pid_write,
        .read           = seq_read,
        .llseek         = tracing_lseek,
        .release        = ftrace_pid_release,
};

static const struct file_operations ftrace_no_pid_fops = {
        .open           = ftrace_no_pid_open,
        .write          = ftrace_no_pid_write,
        .read           = seq_read,
        .llseek         = tracing_lseek,
        .release        = ftrace_pid_release,
};

void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer)
{
        trace_create_file("set_ftrace_pid", TRACE_MODE_WRITE, d_tracer,
                            tr, &ftrace_pid_fops);
        trace_create_file("set_ftrace_notrace_pid", TRACE_MODE_WRITE,
                          d_tracer, tr, &ftrace_no_pid_fops);
}

void __init ftrace_init_tracefs_toplevel(struct trace_array *tr,
                                         struct dentry *d_tracer)
{
        /* Only the top level directory has the dyn_tracefs and profile */
        WARN_ON(!(tr->flags & TRACE_ARRAY_FL_GLOBAL));

        ftrace_init_dyn_tracefs(d_tracer);
        ftrace_profile_tracefs(d_tracer);
}

/**
 * ftrace_kill - kill ftrace
 *
 * This function should be used by panic code. It stops ftrace
 * but in a not so nice way. If you need to simply kill ftrace
 * from a non-atomic section, use ftrace_kill.
 */
void ftrace_kill(void)
{
        ftrace_disabled = 1;
        ftrace_enabled = 0;
        ftrace_trace_function = ftrace_stub;
}

/**
 * ftrace_is_dead - Test if ftrace is dead or not.
 *
 * Returns: 1 if ftrace is "dead", zero otherwise.
 */
int ftrace_is_dead(void)
{
        return ftrace_disabled;
}

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
/*
 * When registering ftrace_ops with IPMODIFY, it is necessary to make sure
 * it doesn't conflict with any direct ftrace_ops. If there is existing
 * direct ftrace_ops on a kernel function being patched, call
 * FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER on it to enable sharing.
 *
 * @ops:     ftrace_ops being registered.
 *
 * Returns:
 *         0 on success;
 *         Negative on failure.
 */
static int prepare_direct_functions_for_ipmodify(struct ftrace_ops *ops)
{
        struct ftrace_func_entry *entry;
        struct ftrace_hash *hash;
        struct ftrace_ops *op;
        int size, i, ret;

        lockdep_assert_held_once(&direct_mutex);

        if (!(ops->flags & FTRACE_OPS_FL_IPMODIFY))
                return 0;

        hash = ops->func_hash->filter_hash;
        size = 1 << hash->size_bits;
        for (i = 0; i < size; i++) {
                hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
                        unsigned long ip = entry->ip;
                        bool found_op = false;

                        mutex_lock(&ftrace_lock);
                        do_for_each_ftrace_op(op, ftrace_ops_list) {
                                if (!(op->flags & FTRACE_OPS_FL_DIRECT))
                                        continue;
                                if (ops_references_ip(op, ip)) {
                                        found_op = true;
                                        break;
                                }
                        } while_for_each_ftrace_op(op);
                        mutex_unlock(&ftrace_lock);

                        if (found_op) {
                                if (!op->ops_func)
                                        return -EBUSY;

                                ret = op->ops_func(op, FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER);
                                if (ret)
                                        return ret;
                        }
                }
        }

        return 0;
}

/*
 * Similar to prepare_direct_functions_for_ipmodify, clean up after ops
 * with IPMODIFY is unregistered. The cleanup is optional for most DIRECT
 * ops.
 */
static void cleanup_direct_functions_after_ipmodify(struct ftrace_ops *ops)
{
        struct ftrace_func_entry *entry;
        struct ftrace_hash *hash;
        struct ftrace_ops *op;
        int size, i;

        if (!(ops->flags & FTRACE_OPS_FL_IPMODIFY))
                return;

        mutex_lock(&direct_mutex);

        hash = ops->func_hash->filter_hash;
        size = 1 << hash->size_bits;
        for (i = 0; i < size; i++) {
                hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
                        unsigned long ip = entry->ip;
                        bool found_op = false;

                        mutex_lock(&ftrace_lock);
                        do_for_each_ftrace_op(op, ftrace_ops_list) {
                                if (!(op->flags & FTRACE_OPS_FL_DIRECT))
                                        continue;
                                if (ops_references_ip(op, ip)) {
                                        found_op = true;
                                        break;
                                }
                        } while_for_each_ftrace_op(op);
                        mutex_unlock(&ftrace_lock);

                        /* The cleanup is optional, ignore any errors */
                        if (found_op && op->ops_func)
                                op->ops_func(op, FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER);
                }
        }
        mutex_unlock(&direct_mutex);
}

#define lock_direct_mutex()     mutex_lock(&direct_mutex)
#define unlock_direct_mutex()   mutex_unlock(&direct_mutex)

#else  /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */

static int prepare_direct_functions_for_ipmodify(struct ftrace_ops *ops)
{
        return 0;
}

static void cleanup_direct_functions_after_ipmodify(struct ftrace_ops *ops)
{
}

#define lock_direct_mutex()     do { } while (0)
#define unlock_direct_mutex()   do { } while (0)

#endif  /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */

/*
 * Similar to register_ftrace_function, except we don't lock direct_mutex.
 */
static int register_ftrace_function_nolock(struct ftrace_ops *ops)
{
        int ret;

        ftrace_ops_init(ops);

        mutex_lock(&ftrace_lock);

        ret = ftrace_startup(ops, 0);

        mutex_unlock(&ftrace_lock);

        return ret;
}

/**
 * register_ftrace_function - register a function for profiling
 * @ops:        ops structure that holds the function for profiling.
 *
 * Register a function to be called by all functions in the
 * kernel.
 *
 * Note: @ops->func and all the functions it calls must be labeled
 *       with "notrace", otherwise it will go into a
 *       recursive loop.
 */
int register_ftrace_function(struct ftrace_ops *ops)
{
        int ret;

        lock_direct_mutex();
        ret = prepare_direct_functions_for_ipmodify(ops);
        if (ret < 0)
                goto out_unlock;

        ret = register_ftrace_function_nolock(ops);

out_unlock:
        unlock_direct_mutex();
        return ret;
}
EXPORT_SYMBOL_GPL(register_ftrace_function);

/**
 * unregister_ftrace_function - unregister a function for profiling.
 * @ops:        ops structure that holds the function to unregister
 *
 * Unregister a function that was added to be called by ftrace profiling.
 */
int unregister_ftrace_function(struct ftrace_ops *ops)
{
        int ret;

        mutex_lock(&ftrace_lock);
        ret = ftrace_shutdown(ops, 0);
        mutex_unlock(&ftrace_lock);

        cleanup_direct_functions_after_ipmodify(ops);
        return ret;
}
EXPORT_SYMBOL_GPL(unregister_ftrace_function);

static int symbols_cmp(const void *a, const void *b)
{
        const char **str_a = (const char **) a;
        const char **str_b = (const char **) b;

        return strcmp(*str_a, *str_b);
}

struct kallsyms_data {
        unsigned long *addrs;
        const char **syms;
        size_t cnt;
        size_t found;
};

/* This function gets called for all kernel and module symbols
 * and returns 1 in case we resolved all the requested symbols,
 * 0 otherwise.
 */
static int kallsyms_callback(void *data, const char *name, unsigned long addr)
{
        struct kallsyms_data *args = data;
        const char **sym;
        int idx;

        sym = bsearch(&name, args->syms, args->cnt, sizeof(*args->syms), symbols_cmp);
        if (!sym)
                return 0;

        idx = sym - args->syms;
        if (args->addrs[idx])
                return 0;

        if (!ftrace_location(addr))
                return 0;

        args->addrs[idx] = addr;
        args->found++;
        return args->found == args->cnt ? 1 : 0;
}

/**
 * ftrace_lookup_symbols - Lookup addresses for array of symbols
 *
 * @sorted_syms: array of symbols pointers symbols to resolve,
 * must be alphabetically sorted
 * @cnt: number of symbols/addresses in @syms/@addrs arrays
 * @addrs: array for storing resulting addresses
 *
 * This function looks up addresses for array of symbols provided in
 * @syms array (must be alphabetically sorted) and stores them in
 * @addrs array, which needs to be big enough to store at least @cnt
 * addresses.
 *
 * Returns: 0 if all provided symbols are found, -ESRCH otherwise.
 */
int ftrace_lookup_symbols(const char **sorted_syms, size_t cnt, unsigned long *addrs)
{
        struct kallsyms_data args;
        int found_all;

        memset(addrs, 0, sizeof(*addrs) * cnt);
        args.addrs = addrs;
        args.syms = sorted_syms;
        args.cnt = cnt;
        args.found = 0;

        found_all = kallsyms_on_each_symbol(kallsyms_callback, &args);
        if (found_all)
                return 0;
        found_all = module_kallsyms_on_each_symbol(NULL, kallsyms_callback, &args);
        return found_all ? 0 : -ESRCH;
}

#ifdef CONFIG_SYSCTL

#ifdef CONFIG_DYNAMIC_FTRACE
static void ftrace_startup_sysctl(void)
{
        int command;

        if (unlikely(ftrace_disabled))
                return;

        /* Force update next time */
        saved_ftrace_func = NULL;
        /* ftrace_start_up is true if we want ftrace running */
        if (ftrace_start_up) {
                command = FTRACE_UPDATE_CALLS;
                if (ftrace_graph_active)
                        command |= FTRACE_START_FUNC_RET;
                ftrace_startup_enable(command);
        }
}

static void ftrace_shutdown_sysctl(void)
{
        int command;

        if (unlikely(ftrace_disabled))
                return;

        /* ftrace_start_up is true if ftrace is running */
        if (ftrace_start_up) {
                command = FTRACE_DISABLE_CALLS;
                if (ftrace_graph_active)
                        command |= FTRACE_STOP_FUNC_RET;
                ftrace_run_update_code(command);
        }
}
#else
# define ftrace_startup_sysctl()       do { } while (0)
# define ftrace_shutdown_sysctl()      do { } while (0)
#endif /* CONFIG_DYNAMIC_FTRACE */

static bool is_permanent_ops_registered(void)
{
        struct ftrace_ops *op;

        do_for_each_ftrace_op(op, ftrace_ops_list) {
                if (op->flags & FTRACE_OPS_FL_PERMANENT)
                        return true;
        } while_for_each_ftrace_op(op);

        return false;
}

static int
ftrace_enable_sysctl(struct ctl_table *table, int write,
                     void *buffer, size_t *lenp, loff_t *ppos)
{
        int ret = -ENODEV;

        mutex_lock(&ftrace_lock);

        if (unlikely(ftrace_disabled))
                goto out;

        ret = proc_dointvec(table, write, buffer, lenp, ppos);

        if (ret || !write || (last_ftrace_enabled == !!ftrace_enabled))
                goto out;

        if (ftrace_enabled) {

                /* we are starting ftrace again */
                if (rcu_dereference_protected(ftrace_ops_list,
                        lockdep_is_held(&ftrace_lock)) != &ftrace_list_end)
                        update_ftrace_function();

                ftrace_startup_sysctl();

        } else {
                if (is_permanent_ops_registered()) {
                        ftrace_enabled = true;
                        ret = -EBUSY;
                        goto out;
                }

                /* stopping ftrace calls (just send to ftrace_stub) */
                ftrace_trace_function = ftrace_stub;

                ftrace_shutdown_sysctl();
        }

        last_ftrace_enabled = !!ftrace_enabled;
 out:
        mutex_unlock(&ftrace_lock);
        return ret;
}

static struct ctl_table ftrace_sysctls[] = {
        {
                .procname       = "ftrace_enabled",
                .data           = &ftrace_enabled,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = ftrace_enable_sysctl,
        },
        {}
};

static int __init ftrace_sysctl_init(void)
{
        register_sysctl_init("kernel", ftrace_sysctls);
        return 0;
}
late_initcall(ftrace_sysctl_init);
#endif