fs: smb: common: add missing MODULE_DESCRIPTION() macros

[sfrench/cifs-2.6.git] / arch / s390 / kernel / perf_cpum_cf.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Performance event support for s390x - CPU-measurement Counter Facility
 *
 *  Copyright IBM Corp. 2012, 2023
 *  Author(s): Hendrik Brueckner <brueckner@linux.ibm.com>
 *             Thomas Richter <tmricht@linux.ibm.com>
 */
#define KMSG_COMPONENT  "cpum_cf"
#define pr_fmt(fmt)     KMSG_COMPONENT ": " fmt

#include <linux/kernel.h>
#include <linux/kernel_stat.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/miscdevice.h>
#include <linux/perf_event.h>

#include <asm/cpu_mf.h>
#include <asm/hwctrset.h>
#include <asm/debug.h>

enum cpumf_ctr_set {
        CPUMF_CTR_SET_BASIC   = 0,    /* Basic Counter Set */
        CPUMF_CTR_SET_USER    = 1,    /* Problem-State Counter Set */
        CPUMF_CTR_SET_CRYPTO  = 2,    /* Crypto-Activity Counter Set */
        CPUMF_CTR_SET_EXT     = 3,    /* Extended Counter Set */
        CPUMF_CTR_SET_MT_DIAG = 4,    /* MT-diagnostic Counter Set */

        /* Maximum number of counter sets */
        CPUMF_CTR_SET_MAX,
};

#define CPUMF_LCCTL_ENABLE_SHIFT    16
#define CPUMF_LCCTL_ACTCTL_SHIFT     0

static inline void ctr_set_enable(u64 *state, u64 ctrsets)
{
        *state |= ctrsets << CPUMF_LCCTL_ENABLE_SHIFT;
}

static inline void ctr_set_disable(u64 *state, u64 ctrsets)
{
        *state &= ~(ctrsets << CPUMF_LCCTL_ENABLE_SHIFT);
}

static inline void ctr_set_start(u64 *state, u64 ctrsets)
{
        *state |= ctrsets << CPUMF_LCCTL_ACTCTL_SHIFT;
}

static inline void ctr_set_stop(u64 *state, u64 ctrsets)
{
        *state &= ~(ctrsets << CPUMF_LCCTL_ACTCTL_SHIFT);
}

static inline int ctr_stcctm(enum cpumf_ctr_set set, u64 range, u64 *dest)
{
        switch (set) {
        case CPUMF_CTR_SET_BASIC:
                return stcctm(BASIC, range, dest);
        case CPUMF_CTR_SET_USER:
                return stcctm(PROBLEM_STATE, range, dest);
        case CPUMF_CTR_SET_CRYPTO:
                return stcctm(CRYPTO_ACTIVITY, range, dest);
        case CPUMF_CTR_SET_EXT:
                return stcctm(EXTENDED, range, dest);
        case CPUMF_CTR_SET_MT_DIAG:
                return stcctm(MT_DIAG_CLEARING, range, dest);
        case CPUMF_CTR_SET_MAX:
                return 3;
        }
        return 3;
}

struct cpu_cf_events {
        refcount_t refcnt;              /* Reference count */
        atomic_t                ctr_set[CPUMF_CTR_SET_MAX];
        u64                     state;          /* For perf_event_open SVC */
        u64                     dev_state;      /* For /dev/hwctr */
        unsigned int            flags;
        size_t used;                    /* Bytes used in data */
        size_t usedss;                  /* Bytes used in start/stop */
        unsigned char start[PAGE_SIZE]; /* Counter set at event add */
        unsigned char stop[PAGE_SIZE];  /* Counter set at event delete */
        unsigned char data[PAGE_SIZE];  /* Counter set at /dev/hwctr */
        unsigned int sets;              /* # Counter set saved in memory */
};

static unsigned int cfdiag_cpu_speed;   /* CPU speed for CF_DIAG trailer */
static debug_info_t *cf_dbg;

/*
 * The CPU Measurement query counter information instruction contains
 * information which varies per machine generation, but is constant and
 * does not change when running on a particular machine, such as counter
 * first and second version number. This is needed to determine the size
 * of counter sets. Extract this information at device driver initialization.
 */
static struct cpumf_ctr_info    cpumf_ctr_info;

struct cpu_cf_ptr {
        struct cpu_cf_events *cpucf;
};

static struct cpu_cf_root {             /* Anchor to per CPU data */
        refcount_t refcnt;              /* Overall active events */
        struct cpu_cf_ptr __percpu *cfptr;
} cpu_cf_root;

/*
 * Serialize event initialization and event removal. Both are called from
 * user space in task context with perf_event_open() and close()
 * system calls.
 *
 * This mutex serializes functions cpum_cf_alloc_cpu() called at event
 * initialization via cpumf_pmu_event_init() and function cpum_cf_free_cpu()
 * called at event removal via call back function hw_perf_event_destroy()
 * when the event is deleted. They are serialized to enforce correct
 * bookkeeping of pointer and reference counts anchored by
 * struct cpu_cf_root and the access to cpu_cf_root::refcnt and the
 * per CPU pointers stored in cpu_cf_root::cfptr.
 */
static DEFINE_MUTEX(pmc_reserve_mutex);

/*
 * Get pointer to per-cpu structure.
 *
 * Function get_cpu_cfhw() is called from
 * - cfset_copy_all(): This function is protected by cpus_read_lock(), so
 *   CPU hot plug remove can not happen. Event removal requires a close()
 *   first.
 *
 * Function this_cpu_cfhw() is called from perf common code functions:
 * - pmu_{en|dis}able(), pmu_{add|del}()and pmu_{start|stop}():
 *   All functions execute with interrupts disabled on that particular CPU.
 * - cfset_ioctl_{on|off}, cfset_cpu_read(): see comment cfset_copy_all().
 *
 * Therefore it is safe to access the CPU specific pointer to the event.
 */
static struct cpu_cf_events *get_cpu_cfhw(int cpu)
{
        struct cpu_cf_ptr __percpu *p = cpu_cf_root.cfptr;

        if (p) {
                struct cpu_cf_ptr *q = per_cpu_ptr(p, cpu);

                return q->cpucf;
        }
        return NULL;
}

static struct cpu_cf_events *this_cpu_cfhw(void)
{
        return get_cpu_cfhw(smp_processor_id());
}

/* Disable counter sets on dedicated CPU */
static void cpum_cf_reset_cpu(void *flags)
{
        lcctl(0);
}

/* Free per CPU data when the last event is removed. */
static void cpum_cf_free_root(void)
{
        if (!refcount_dec_and_test(&cpu_cf_root.refcnt))
                return;
        free_percpu(cpu_cf_root.cfptr);
        cpu_cf_root.cfptr = NULL;
        irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);
        on_each_cpu(cpum_cf_reset_cpu, NULL, 1);
        debug_sprintf_event(cf_dbg, 4, "%s root.refcnt %u cfptr %d\n",
                            __func__, refcount_read(&cpu_cf_root.refcnt),
                            !cpu_cf_root.cfptr);
}

/*
 * On initialization of first event also allocate per CPU data dynamically.
 * Start with an array of pointers, the array size is the maximum number of
 * CPUs possible, which might be larger than the number of CPUs currently
 * online.
 */
static int cpum_cf_alloc_root(void)
{
        int rc = 0;

        if (refcount_inc_not_zero(&cpu_cf_root.refcnt))
                return rc;

        /* The memory is already zeroed. */
        cpu_cf_root.cfptr = alloc_percpu(struct cpu_cf_ptr);
        if (cpu_cf_root.cfptr) {
                refcount_set(&cpu_cf_root.refcnt, 1);
                on_each_cpu(cpum_cf_reset_cpu, NULL, 1);
                irq_subclass_register(IRQ_SUBCLASS_MEASUREMENT_ALERT);
        } else {
                rc = -ENOMEM;
        }

        return rc;
}

/* Free CPU counter data structure for a PMU */
static void cpum_cf_free_cpu(int cpu)
{
        struct cpu_cf_events *cpuhw;
        struct cpu_cf_ptr *p;

        mutex_lock(&pmc_reserve_mutex);
        /*
         * When invoked via CPU hotplug handler, there might be no events
         * installed or that particular CPU might not have an
         * event installed. This anchor pointer can be NULL!
         */
        if (!cpu_cf_root.cfptr)
                goto out;
        p = per_cpu_ptr(cpu_cf_root.cfptr, cpu);
        cpuhw = p->cpucf;
        /*
         * Might be zero when called from CPU hotplug handler and no event
         * installed on that CPU, but on different CPUs.
         */
        if (!cpuhw)
                goto out;

        if (refcount_dec_and_test(&cpuhw->refcnt)) {
                kfree(cpuhw);
                p->cpucf = NULL;
        }
        cpum_cf_free_root();
out:
        mutex_unlock(&pmc_reserve_mutex);
}

/* Allocate CPU counter data structure for a PMU. Called under mutex lock. */
static int cpum_cf_alloc_cpu(int cpu)
{
        struct cpu_cf_events *cpuhw;
        struct cpu_cf_ptr *p;
        int rc;

        mutex_lock(&pmc_reserve_mutex);
        rc = cpum_cf_alloc_root();
        if (rc)
                goto unlock;
        p = per_cpu_ptr(cpu_cf_root.cfptr, cpu);
        cpuhw = p->cpucf;

        if (!cpuhw) {
                cpuhw = kzalloc(sizeof(*cpuhw), GFP_KERNEL);
                if (cpuhw) {
                        p->cpucf = cpuhw;
                        refcount_set(&cpuhw->refcnt, 1);
                } else {
                        rc = -ENOMEM;
                }
        } else {
                refcount_inc(&cpuhw->refcnt);
        }
        if (rc) {
                /*
                 * Error in allocation of event, decrement anchor. Since
                 * cpu_cf_event in not created, its destroy() function is not
                 * invoked. Adjust the reference counter for the anchor.
                 */
                cpum_cf_free_root();
        }
unlock:
        mutex_unlock(&pmc_reserve_mutex);
        return rc;
}

/*
 * Create/delete per CPU data structures for /dev/hwctr interface and events
 * created by perf_event_open().
 * If cpu is -1, track task on all available CPUs. This requires
 * allocation of hardware data structures for all CPUs. This setup handles
 * perf_event_open() with task context and /dev/hwctr interface.
 * If cpu is non-zero install event on this CPU only. This setup handles
 * perf_event_open() with CPU context.
 */
static int cpum_cf_alloc(int cpu)
{
        cpumask_var_t mask;
        int rc;

        if (cpu == -1) {
                if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
                        return -ENOMEM;
                for_each_online_cpu(cpu) {
                        rc = cpum_cf_alloc_cpu(cpu);
                        if (rc) {
                                for_each_cpu(cpu, mask)
                                        cpum_cf_free_cpu(cpu);
                                break;
                        }
                        cpumask_set_cpu(cpu, mask);
                }
                free_cpumask_var(mask);
        } else {
                rc = cpum_cf_alloc_cpu(cpu);
        }
        return rc;
}

static void cpum_cf_free(int cpu)
{
        if (cpu == -1) {
                for_each_online_cpu(cpu)
                        cpum_cf_free_cpu(cpu);
        } else {
                cpum_cf_free_cpu(cpu);
        }
}

#define CF_DIAG_CTRSET_DEF              0xfeef  /* Counter set header mark */
                                                /* interval in seconds */

/* Counter sets are stored as data stream in a page sized memory buffer and
 * exported to user space via raw data attached to the event sample data.
 * Each counter set starts with an eight byte header consisting of:
 * - a two byte eye catcher (0xfeef)
 * - a one byte counter set number
 * - a two byte counter set size (indicates the number of counters in this set)
 * - a three byte reserved value (must be zero) to make the header the same
 *   size as a counter value.
 * All counter values are eight byte in size.
 *
 * All counter sets are followed by a 64 byte trailer.
 * The trailer consists of a:
 * - flag field indicating valid fields when corresponding bit set
 * - the counter facility first and second version number
 * - the CPU speed if nonzero
 * - the time stamp the counter sets have been collected
 * - the time of day (TOD) base value
 * - the machine type.
 *
 * The counter sets are saved when the process is prepared to be executed on a
 * CPU and saved again when the process is going to be removed from a CPU.
 * The difference of both counter sets are calculated and stored in the event
 * sample data area.
 */
struct cf_ctrset_entry {        /* CPU-M CF counter set entry (8 byte) */
        unsigned int def:16;    /* 0-15  Data Entry Format */
        unsigned int set:16;    /* 16-31 Counter set identifier */
        unsigned int ctr:16;    /* 32-47 Number of stored counters */
        unsigned int res1:16;   /* 48-63 Reserved */
};

struct cf_trailer_entry {       /* CPU-M CF_DIAG trailer (64 byte) */
        /* 0 - 7 */
        union {
                struct {
                        unsigned int clock_base:1;      /* TOD clock base set */
                        unsigned int speed:1;           /* CPU speed set */
                        /* Measurement alerts */
                        unsigned int mtda:1;    /* Loss of MT ctr. data alert */
                        unsigned int caca:1;    /* Counter auth. change alert */
                        unsigned int lcda:1;    /* Loss of counter data alert */
                };
                unsigned long flags;    /* 0-63    All indicators */
        };
        /* 8 - 15 */
        unsigned int cfvn:16;                   /* 64-79   Ctr First Version */
        unsigned int csvn:16;                   /* 80-95   Ctr Second Version */
        unsigned int cpu_speed:32;              /* 96-127  CPU speed */
        /* 16 - 23 */
        unsigned long timestamp;                /* 128-191 Timestamp (TOD) */
        /* 24 - 55 */
        union {
                struct {
                        unsigned long progusage1;
                        unsigned long progusage2;
                        unsigned long progusage3;
                        unsigned long tod_base;
                };
                unsigned long progusage[4];
        };
        /* 56 - 63 */
        unsigned int mach_type:16;              /* Machine type */
        unsigned int res1:16;                   /* Reserved */
        unsigned int res2:32;                   /* Reserved */
};

/* Create the trailer data at the end of a page. */
static void cfdiag_trailer(struct cf_trailer_entry *te)
{
        struct cpuid cpuid;

        te->cfvn = cpumf_ctr_info.cfvn;         /* Counter version numbers */
        te->csvn = cpumf_ctr_info.csvn;

        get_cpu_id(&cpuid);                     /* Machine type */
        te->mach_type = cpuid.machine;
        te->cpu_speed = cfdiag_cpu_speed;
        if (te->cpu_speed)
                te->speed = 1;
        te->clock_base = 1;                     /* Save clock base */
        te->tod_base = tod_clock_base.tod;
        te->timestamp = get_tod_clock_fast();
}

/*
 * The number of counters per counter set varies between machine generations,
 * but is constant when running on a particular machine generation.
 * Determine each counter set size at device driver initialization and
 * retrieve it later.
 */
static size_t cpumf_ctr_setsizes[CPUMF_CTR_SET_MAX];
static void cpum_cf_make_setsize(enum cpumf_ctr_set ctrset)
{
        size_t ctrset_size = 0;

        switch (ctrset) {
        case CPUMF_CTR_SET_BASIC:
                if (cpumf_ctr_info.cfvn >= 1)
                        ctrset_size = 6;
                break;
        case CPUMF_CTR_SET_USER:
                if (cpumf_ctr_info.cfvn == 1)
                        ctrset_size = 6;
                else if (cpumf_ctr_info.cfvn >= 3)
                        ctrset_size = 2;
                break;
        case CPUMF_CTR_SET_CRYPTO:
                if (cpumf_ctr_info.csvn >= 1 && cpumf_ctr_info.csvn <= 5)
                        ctrset_size = 16;
                else if (cpumf_ctr_info.csvn >= 6)
                        ctrset_size = 20;
                break;
        case CPUMF_CTR_SET_EXT:
                if (cpumf_ctr_info.csvn == 1)
                        ctrset_size = 32;
                else if (cpumf_ctr_info.csvn == 2)
                        ctrset_size = 48;
                else if (cpumf_ctr_info.csvn >= 3 && cpumf_ctr_info.csvn <= 5)
                        ctrset_size = 128;
                else if (cpumf_ctr_info.csvn == 6 || cpumf_ctr_info.csvn == 7)
                        ctrset_size = 160;
                break;
        case CPUMF_CTR_SET_MT_DIAG:
                if (cpumf_ctr_info.csvn > 3)
                        ctrset_size = 48;
                break;
        case CPUMF_CTR_SET_MAX:
                break;
        }
        cpumf_ctr_setsizes[ctrset] = ctrset_size;
}

/*
 * Return the maximum possible counter set size (in number of 8 byte counters)
 * depending on type and model number.
 */
static size_t cpum_cf_read_setsize(enum cpumf_ctr_set ctrset)
{
        return cpumf_ctr_setsizes[ctrset];
}

/* Read a counter set. The counter set number determines the counter set and
 * the CPUM-CF first and second version number determine the number of
 * available counters in each counter set.
 * Each counter set starts with header containing the counter set number and
 * the number of eight byte counters.
 *
 * The functions returns the number of bytes occupied by this counter set
 * including the header.
 * If there is no counter in the counter set, this counter set is useless and
 * zero is returned on this case.
 *
 * Note that the counter sets may not be enabled or active and the stcctm
 * instruction might return error 3. Depending on error_ok value this is ok,
 * for example when called from cpumf_pmu_start() call back function.
 */
static size_t cfdiag_getctrset(struct cf_ctrset_entry *ctrdata, int ctrset,
                               size_t room, bool error_ok)
{
        size_t ctrset_size, need = 0;
        int rc = 3;                             /* Assume write failure */

        ctrdata->def = CF_DIAG_CTRSET_DEF;
        ctrdata->set = ctrset;
        ctrdata->res1 = 0;
        ctrset_size = cpum_cf_read_setsize(ctrset);

        if (ctrset_size) {                      /* Save data */
                need = ctrset_size * sizeof(u64) + sizeof(*ctrdata);
                if (need <= room) {
                        rc = ctr_stcctm(ctrset, ctrset_size,
                                        (u64 *)(ctrdata + 1));
                }
                if (rc != 3 || error_ok)
                        ctrdata->ctr = ctrset_size;
                else
                        need = 0;
        }

        return need;
}

static const u64 cpumf_ctr_ctl[CPUMF_CTR_SET_MAX] = {
        [CPUMF_CTR_SET_BASIC]   = 0x02,
        [CPUMF_CTR_SET_USER]    = 0x04,
        [CPUMF_CTR_SET_CRYPTO]  = 0x08,
        [CPUMF_CTR_SET_EXT]     = 0x01,
        [CPUMF_CTR_SET_MT_DIAG] = 0x20,
};

/* Read out all counter sets and save them in the provided data buffer.
 * The last 64 byte host an artificial trailer entry.
 */
static size_t cfdiag_getctr(void *data, size_t sz, unsigned long auth,
                            bool error_ok)
{
        struct cf_trailer_entry *trailer;
        size_t offset = 0, done;
        int i;

        memset(data, 0, sz);
        sz -= sizeof(*trailer);         /* Always room for trailer */
        for (i = CPUMF_CTR_SET_BASIC; i < CPUMF_CTR_SET_MAX; ++i) {
                struct cf_ctrset_entry *ctrdata = data + offset;

                if (!(auth & cpumf_ctr_ctl[i]))
                        continue;       /* Counter set not authorized */

                done = cfdiag_getctrset(ctrdata, i, sz - offset, error_ok);
                offset += done;
        }
        trailer = data + offset;
        cfdiag_trailer(trailer);
        return offset + sizeof(*trailer);
}

/* Calculate the difference for each counter in a counter set. */
static void cfdiag_diffctrset(u64 *pstart, u64 *pstop, int counters)
{
        for (; --counters >= 0; ++pstart, ++pstop)
                if (*pstop >= *pstart)
                        *pstop -= *pstart;
                else
                        *pstop = *pstart - *pstop + 1;
}

/* Scan the counter sets and calculate the difference of each counter
 * in each set. The result is the increment of each counter during the
 * period the counter set has been activated.
 *
 * Return true on success.
 */
static int cfdiag_diffctr(struct cpu_cf_events *cpuhw, unsigned long auth)
{
        struct cf_trailer_entry *trailer_start, *trailer_stop;
        struct cf_ctrset_entry *ctrstart, *ctrstop;
        size_t offset = 0;

        auth &= (1 << CPUMF_LCCTL_ENABLE_SHIFT) - 1;
        do {
                ctrstart = (struct cf_ctrset_entry *)(cpuhw->start + offset);
                ctrstop = (struct cf_ctrset_entry *)(cpuhw->stop + offset);

                if (memcmp(ctrstop, ctrstart, sizeof(*ctrstop))) {
                        pr_err_once("cpum_cf_diag counter set compare error "
                                    "in set %i\n", ctrstart->set);
                        return 0;
                }
                auth &= ~cpumf_ctr_ctl[ctrstart->set];
                if (ctrstart->def == CF_DIAG_CTRSET_DEF) {
                        cfdiag_diffctrset((u64 *)(ctrstart + 1),
                                          (u64 *)(ctrstop + 1), ctrstart->ctr);
                        offset += ctrstart->ctr * sizeof(u64) +
                                                        sizeof(*ctrstart);
                }
        } while (ctrstart->def && auth);

        /* Save time_stamp from start of event in stop's trailer */
        trailer_start = (struct cf_trailer_entry *)(cpuhw->start + offset);
        trailer_stop = (struct cf_trailer_entry *)(cpuhw->stop + offset);
        trailer_stop->progusage[0] = trailer_start->timestamp;

        return 1;
}

static enum cpumf_ctr_set get_counter_set(u64 event)
{
        int set = CPUMF_CTR_SET_MAX;

        if (event < 32)
                set = CPUMF_CTR_SET_BASIC;
        else if (event < 64)
                set = CPUMF_CTR_SET_USER;
        else if (event < 128)
                set = CPUMF_CTR_SET_CRYPTO;
        else if (event < 288)
                set = CPUMF_CTR_SET_EXT;
        else if (event >= 448 && event < 496)
                set = CPUMF_CTR_SET_MT_DIAG;

        return set;
}

static int validate_ctr_version(const u64 config, enum cpumf_ctr_set set)
{
        u16 mtdiag_ctl;
        int err = 0;

        /* check required version for counter sets */
        switch (set) {
        case CPUMF_CTR_SET_BASIC:
        case CPUMF_CTR_SET_USER:
                if (cpumf_ctr_info.cfvn < 1)
                        err = -EOPNOTSUPP;
                break;
        case CPUMF_CTR_SET_CRYPTO:
                if ((cpumf_ctr_info.csvn >= 1 && cpumf_ctr_info.csvn <= 5 &&
                     config > 79) || (cpumf_ctr_info.csvn >= 6 && config > 83))
                        err = -EOPNOTSUPP;
                break;
        case CPUMF_CTR_SET_EXT:
                if (cpumf_ctr_info.csvn < 1)
                        err = -EOPNOTSUPP;
                if ((cpumf_ctr_info.csvn == 1 && config > 159) ||
                    (cpumf_ctr_info.csvn == 2 && config > 175) ||
                    (cpumf_ctr_info.csvn >= 3 && cpumf_ctr_info.csvn <= 5 &&
                     config > 255) ||
                    (cpumf_ctr_info.csvn >= 6 && config > 287))
                        err = -EOPNOTSUPP;
                break;
        case CPUMF_CTR_SET_MT_DIAG:
                if (cpumf_ctr_info.csvn <= 3)
                        err = -EOPNOTSUPP;
                /*
                 * MT-diagnostic counters are read-only.  The counter set
                 * is automatically enabled and activated on all CPUs with
                 * multithreading (SMT).  Deactivation of multithreading
                 * also disables the counter set.  State changes are ignored
                 * by lcctl().  Because Linux controls SMT enablement through
                 * a kernel parameter only, the counter set is either disabled
                 * or enabled and active.
                 *
                 * Thus, the counters can only be used if SMT is on and the
                 * counter set is enabled and active.
                 */
                mtdiag_ctl = cpumf_ctr_ctl[CPUMF_CTR_SET_MT_DIAG];
                if (!((cpumf_ctr_info.auth_ctl & mtdiag_ctl) &&
                      (cpumf_ctr_info.enable_ctl & mtdiag_ctl) &&
                      (cpumf_ctr_info.act_ctl & mtdiag_ctl)))
                        err = -EOPNOTSUPP;
                break;
        case CPUMF_CTR_SET_MAX:
                err = -EOPNOTSUPP;
        }

        return err;
}

/*
 * Change the CPUMF state to active.
 * Enable and activate the CPU-counter sets according
 * to the per-cpu control state.
 */
static void cpumf_pmu_enable(struct pmu *pmu)
{
        struct cpu_cf_events *cpuhw = this_cpu_cfhw();
        int err;

        if (!cpuhw || (cpuhw->flags & PMU_F_ENABLED))
                return;

        err = lcctl(cpuhw->state | cpuhw->dev_state);
        if (err)
                pr_err("Enabling the performance measuring unit failed with rc=%x\n", err);
        else
                cpuhw->flags |= PMU_F_ENABLED;
}

/*
 * Change the CPUMF state to inactive.
 * Disable and enable (inactive) the CPU-counter sets according
 * to the per-cpu control state.
 */
static void cpumf_pmu_disable(struct pmu *pmu)
{
        struct cpu_cf_events *cpuhw = this_cpu_cfhw();
        u64 inactive;
        int err;

        if (!cpuhw || !(cpuhw->flags & PMU_F_ENABLED))
                return;

        inactive = cpuhw->state & ~((1 << CPUMF_LCCTL_ENABLE_SHIFT) - 1);
        inactive |= cpuhw->dev_state;
        err = lcctl(inactive);
        if (err)
                pr_err("Disabling the performance measuring unit failed with rc=%x\n", err);
        else
                cpuhw->flags &= ~PMU_F_ENABLED;
}

/* Release the PMU if event is the last perf event */
static void hw_perf_event_destroy(struct perf_event *event)
{
        cpum_cf_free(event->cpu);
}

/* CPUMF <-> perf event mappings for kernel+userspace (basic set) */
static const int cpumf_generic_events_basic[] = {
        [PERF_COUNT_HW_CPU_CYCLES]          = 0,
        [PERF_COUNT_HW_INSTRUCTIONS]        = 1,
        [PERF_COUNT_HW_CACHE_REFERENCES]    = -1,
        [PERF_COUNT_HW_CACHE_MISSES]        = -1,
        [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = -1,
        [PERF_COUNT_HW_BRANCH_MISSES]       = -1,
        [PERF_COUNT_HW_BUS_CYCLES]          = -1,
};
/* CPUMF <-> perf event mappings for userspace (problem-state set) */
static const int cpumf_generic_events_user[] = {
        [PERF_COUNT_HW_CPU_CYCLES]          = 32,
        [PERF_COUNT_HW_INSTRUCTIONS]        = 33,
        [PERF_COUNT_HW_CACHE_REFERENCES]    = -1,
        [PERF_COUNT_HW_CACHE_MISSES]        = -1,
        [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = -1,
        [PERF_COUNT_HW_BRANCH_MISSES]       = -1,
        [PERF_COUNT_HW_BUS_CYCLES]          = -1,
};

static int is_userspace_event(u64 ev)
{
        return cpumf_generic_events_user[PERF_COUNT_HW_CPU_CYCLES] == ev ||
               cpumf_generic_events_user[PERF_COUNT_HW_INSTRUCTIONS] == ev;
}

static int __hw_perf_event_init(struct perf_event *event, unsigned int type)
{
        struct perf_event_attr *attr = &event->attr;
        struct hw_perf_event *hwc = &event->hw;
        enum cpumf_ctr_set set;
        u64 ev;

        switch (type) {
        case PERF_TYPE_RAW:
                /* Raw events are used to access counters directly,
                 * hence do not permit excludes */
                if (attr->exclude_kernel || attr->exclude_user ||
                    attr->exclude_hv)
                        return -EOPNOTSUPP;
                ev = attr->config;
                break;

        case PERF_TYPE_HARDWARE:
                if (is_sampling_event(event))   /* No sampling support */
                        return -ENOENT;
                ev = attr->config;
                if (!attr->exclude_user && attr->exclude_kernel) {
                        /*
                         * Count user space (problem-state) only
                         * Handle events 32 and 33 as 0:u and 1:u
                         */
                        if (!is_userspace_event(ev)) {
                                if (ev >= ARRAY_SIZE(cpumf_generic_events_user))
                                        return -EOPNOTSUPP;
                                ev = cpumf_generic_events_user[ev];
                        }
                } else if (!attr->exclude_kernel && attr->exclude_user) {
                        /* No support for kernel space counters only */
                        return -EOPNOTSUPP;
                } else {
                        /* Count user and kernel space, incl. events 32 + 33 */
                        if (!is_userspace_event(ev)) {
                                if (ev >= ARRAY_SIZE(cpumf_generic_events_basic))
                                        return -EOPNOTSUPP;
                                ev = cpumf_generic_events_basic[ev];
                        }
                }
                break;

        default:
                return -ENOENT;
        }

        if (ev == -1)
                return -ENOENT;

        if (ev > PERF_CPUM_CF_MAX_CTR)
                return -ENOENT;

        /* Obtain the counter set to which the specified counter belongs */
        set = get_counter_set(ev);
        switch (set) {
        case CPUMF_CTR_SET_BASIC:
        case CPUMF_CTR_SET_USER:
        case CPUMF_CTR_SET_CRYPTO:
        case CPUMF_CTR_SET_EXT:
        case CPUMF_CTR_SET_MT_DIAG:
                /*
                 * Use the hardware perf event structure to store the
                 * counter number in the 'config' member and the counter
                 * set number in the 'config_base' as bit mask.
                 * It is later used to enable/disable the counter(s).
                 */
                hwc->config = ev;
                hwc->config_base = cpumf_ctr_ctl[set];
                break;
        case CPUMF_CTR_SET_MAX:
                /* The counter could not be associated to a counter set */
                return -EINVAL;
        }

        /* Initialize for using the CPU-measurement counter facility */
        if (cpum_cf_alloc(event->cpu))
                return -ENOMEM;
        event->destroy = hw_perf_event_destroy;

        /*
         * Finally, validate version and authorization of the counter set.
         * If the particular CPU counter set is not authorized,
         * return with -ENOENT in order to fall back to other
         * PMUs that might suffice the event request.
         */
        if (!(hwc->config_base & cpumf_ctr_info.auth_ctl))
                return -ENOENT;
        return validate_ctr_version(hwc->config, set);
}

/* Events CPU_CYLCES and INSTRUCTIONS can be submitted with two different
 * attribute::type values:
 * - PERF_TYPE_HARDWARE:
 * - pmu->type:
 * Handle both type of invocations identical. They address the same hardware.
 * The result is different when event modifiers exclude_kernel and/or
 * exclude_user are also set.
 */
static int cpumf_pmu_event_type(struct perf_event *event)
{
        u64 ev = event->attr.config;

        if (cpumf_generic_events_basic[PERF_COUNT_HW_CPU_CYCLES] == ev ||
            cpumf_generic_events_basic[PERF_COUNT_HW_INSTRUCTIONS] == ev ||
            cpumf_generic_events_user[PERF_COUNT_HW_CPU_CYCLES] == ev ||
            cpumf_generic_events_user[PERF_COUNT_HW_INSTRUCTIONS] == ev)
                return PERF_TYPE_HARDWARE;
        return PERF_TYPE_RAW;
}

static int cpumf_pmu_event_init(struct perf_event *event)
{
        unsigned int type = event->attr.type;
        int err;

        if (type == PERF_TYPE_HARDWARE || type == PERF_TYPE_RAW)
                err = __hw_perf_event_init(event, type);
        else if (event->pmu->type == type)
                /* Registered as unknown PMU */
                err = __hw_perf_event_init(event, cpumf_pmu_event_type(event));
        else
                return -ENOENT;

        if (unlikely(err) && event->destroy)
                event->destroy(event);

        return err;
}

static int hw_perf_event_reset(struct perf_event *event)
{
        u64 prev, new;
        int err;

        do {
                prev = local64_read(&event->hw.prev_count);
                err = ecctr(event->hw.config, &new);
                if (err) {
                        if (err != 3)
                                break;
                        /* The counter is not (yet) available. This
                         * might happen if the counter set to which
                         * this counter belongs is in the disabled
                         * state.
                         */
                        new = 0;
                }
        } while (local64_cmpxchg(&event->hw.prev_count, prev, new) != prev);

        return err;
}

static void hw_perf_event_update(struct perf_event *event)
{
        u64 prev, new, delta;
        int err;

        do {
                prev = local64_read(&event->hw.prev_count);
                err = ecctr(event->hw.config, &new);
                if (err)
                        return;
        } while (local64_cmpxchg(&event->hw.prev_count, prev, new) != prev);

        delta = (prev <= new) ? new - prev
                              : (-1ULL - prev) + new + 1;        /* overflow */
        local64_add(delta, &event->count);
}

static void cpumf_pmu_read(struct perf_event *event)
{
        if (event->hw.state & PERF_HES_STOPPED)
                return;

        hw_perf_event_update(event);
}

static void cpumf_pmu_start(struct perf_event *event, int flags)
{
        struct cpu_cf_events *cpuhw = this_cpu_cfhw();
        struct hw_perf_event *hwc = &event->hw;
        int i;

        if (!(hwc->state & PERF_HES_STOPPED))
                return;

        hwc->state = 0;

        /* (Re-)enable and activate the counter set */
        ctr_set_enable(&cpuhw->state, hwc->config_base);
        ctr_set_start(&cpuhw->state, hwc->config_base);

        /* The counter set to which this counter belongs can be already active.
         * Because all counters in a set are active, the event->hw.prev_count
         * needs to be synchronized.  At this point, the counter set can be in
         * the inactive or disabled state.
         */
        if (hwc->config == PERF_EVENT_CPUM_CF_DIAG) {
                cpuhw->usedss = cfdiag_getctr(cpuhw->start,
                                              sizeof(cpuhw->start),
                                              hwc->config_base, true);
        } else {
                hw_perf_event_reset(event);
        }

        /* Increment refcount for counter sets */
        for (i = CPUMF_CTR_SET_BASIC; i < CPUMF_CTR_SET_MAX; ++i)
                if ((hwc->config_base & cpumf_ctr_ctl[i]))
                        atomic_inc(&cpuhw->ctr_set[i]);
}

/* Create perf event sample with the counter sets as raw data.  The sample
 * is then pushed to the event subsystem and the function checks for
 * possible event overflows. If an event overflow occurs, the PMU is
 * stopped.
 *
 * Return non-zero if an event overflow occurred.
 */
static int cfdiag_push_sample(struct perf_event *event,
                              struct cpu_cf_events *cpuhw)
{
        struct perf_sample_data data;
        struct perf_raw_record raw;
        struct pt_regs regs;
        int overflow;

        /* Setup perf sample */
        perf_sample_data_init(&data, 0, event->hw.last_period);
        memset(&regs, 0, sizeof(regs));
        memset(&raw, 0, sizeof(raw));

        if (event->attr.sample_type & PERF_SAMPLE_CPU)
                data.cpu_entry.cpu = event->cpu;
        if (event->attr.sample_type & PERF_SAMPLE_RAW) {
                raw.frag.size = cpuhw->usedss;
                raw.frag.data = cpuhw->stop;
                perf_sample_save_raw_data(&data, &raw);
        }

        overflow = perf_event_overflow(event, &data, &regs);
        if (overflow)
                event->pmu->stop(event, 0);

        perf_event_update_userpage(event);
        return overflow;
}

static void cpumf_pmu_stop(struct perf_event *event, int flags)
{
        struct cpu_cf_events *cpuhw = this_cpu_cfhw();
        struct hw_perf_event *hwc = &event->hw;
        int i;

        if (!(hwc->state & PERF_HES_STOPPED)) {
                /* Decrement reference count for this counter set and if this
                 * is the last used counter in the set, clear activation
                 * control and set the counter set state to inactive.
                 */
                for (i = CPUMF_CTR_SET_BASIC; i < CPUMF_CTR_SET_MAX; ++i) {
                        if (!(hwc->config_base & cpumf_ctr_ctl[i]))
                                continue;
                        if (!atomic_dec_return(&cpuhw->ctr_set[i]))
                                ctr_set_stop(&cpuhw->state, cpumf_ctr_ctl[i]);
                }
                hwc->state |= PERF_HES_STOPPED;
        }

        if ((flags & PERF_EF_UPDATE) && !(hwc->state & PERF_HES_UPTODATE)) {
                if (hwc->config == PERF_EVENT_CPUM_CF_DIAG) {
                        local64_inc(&event->count);
                        cpuhw->usedss = cfdiag_getctr(cpuhw->stop,
                                                      sizeof(cpuhw->stop),
                                                      event->hw.config_base,
                                                      false);
                        if (cfdiag_diffctr(cpuhw, event->hw.config_base))
                                cfdiag_push_sample(event, cpuhw);
                } else {
                        hw_perf_event_update(event);
                }
                hwc->state |= PERF_HES_UPTODATE;
        }
}

static int cpumf_pmu_add(struct perf_event *event, int flags)
{
        struct cpu_cf_events *cpuhw = this_cpu_cfhw();

        ctr_set_enable(&cpuhw->state, event->hw.config_base);
        event->hw.state = PERF_HES_UPTODATE | PERF_HES_STOPPED;

        if (flags & PERF_EF_START)
                cpumf_pmu_start(event, PERF_EF_RELOAD);

        return 0;
}

static void cpumf_pmu_del(struct perf_event *event, int flags)
{
        struct cpu_cf_events *cpuhw = this_cpu_cfhw();
        int i;

        cpumf_pmu_stop(event, PERF_EF_UPDATE);

        /* Check if any counter in the counter set is still used.  If not used,
         * change the counter set to the disabled state.  This also clears the
         * content of all counters in the set.
         *
         * When a new perf event has been added but not yet started, this can
         * clear enable control and resets all counters in a set.  Therefore,
         * cpumf_pmu_start() always has to reenable a counter set.
         */
        for (i = CPUMF_CTR_SET_BASIC; i < CPUMF_CTR_SET_MAX; ++i)
                if (!atomic_read(&cpuhw->ctr_set[i]))
                        ctr_set_disable(&cpuhw->state, cpumf_ctr_ctl[i]);
}

/* Performance monitoring unit for s390x */
static struct pmu cpumf_pmu = {
        .task_ctx_nr  = perf_sw_context,
        .capabilities = PERF_PMU_CAP_NO_INTERRUPT,
        .pmu_enable   = cpumf_pmu_enable,
        .pmu_disable  = cpumf_pmu_disable,
        .event_init   = cpumf_pmu_event_init,
        .add          = cpumf_pmu_add,
        .del          = cpumf_pmu_del,
        .start        = cpumf_pmu_start,
        .stop         = cpumf_pmu_stop,
        .read         = cpumf_pmu_read,
};

static struct cfset_session {           /* CPUs and counter set bit mask */
        struct list_head head;          /* Head of list of active processes */
} cfset_session = {
        .head = LIST_HEAD_INIT(cfset_session.head)
};

static refcount_t cfset_opencnt = REFCOUNT_INIT(0);     /* Access count */
/*
 * Synchronize access to device /dev/hwc. This mutex protects against
 * concurrent access to functions cfset_open() and cfset_release().
 * Same for CPU hotplug add and remove events triggering
 * cpum_cf_online_cpu() and cpum_cf_offline_cpu().
 * It also serializes concurrent device ioctl access from multiple
 * processes accessing /dev/hwc.
 *
 * The mutex protects concurrent access to the /dev/hwctr session management
 * struct cfset_session and reference counting variable cfset_opencnt.
 */
static DEFINE_MUTEX(cfset_ctrset_mutex);

/*
 * CPU hotplug handles only /dev/hwctr device.
 * For perf_event_open() the CPU hotplug handling is done on kernel common
 * code:
 * - CPU add: Nothing is done since a file descriptor can not be created
 *   and returned to the user.
 * - CPU delete: Handled by common code via pmu_disable(), pmu_stop() and
 *   pmu_delete(). The event itself is removed when the file descriptor is
 *   closed.
 */
static int cfset_online_cpu(unsigned int cpu);

static int cpum_cf_online_cpu(unsigned int cpu)
{
        int rc = 0;

        /*
         * Ignore notification for perf_event_open().
         * Handle only /dev/hwctr device sessions.
         */
        mutex_lock(&cfset_ctrset_mutex);
        if (refcount_read(&cfset_opencnt)) {
                rc = cpum_cf_alloc_cpu(cpu);
                if (!rc)
                        cfset_online_cpu(cpu);
        }
        mutex_unlock(&cfset_ctrset_mutex);
        return rc;
}

static int cfset_offline_cpu(unsigned int cpu);

static int cpum_cf_offline_cpu(unsigned int cpu)
{
        /*
         * During task exit processing of grouped perf events triggered by CPU
         * hotplug processing, pmu_disable() is called as part of perf context
         * removal process. Therefore do not trigger event removal now for
         * perf_event_open() created events. Perf common code triggers event
         * destruction when the event file descriptor is closed.
         *
         * Handle only /dev/hwctr device sessions.
         */
        mutex_lock(&cfset_ctrset_mutex);
        if (refcount_read(&cfset_opencnt)) {
                cfset_offline_cpu(cpu);
                cpum_cf_free_cpu(cpu);
        }
        mutex_unlock(&cfset_ctrset_mutex);
        return 0;
}

/* Return true if store counter set multiple instruction is available */
static inline int stccm_avail(void)
{
        return test_facility(142);
}

/* CPU-measurement alerts for the counter facility */
static void cpumf_measurement_alert(struct ext_code ext_code,
                                    unsigned int alert, unsigned long unused)
{
        struct cpu_cf_events *cpuhw;

        if (!(alert & CPU_MF_INT_CF_MASK))
                return;

        inc_irq_stat(IRQEXT_CMC);

        /*
         * Measurement alerts are shared and might happen when the PMU
         * is not reserved.  Ignore these alerts in this case.
         */
        cpuhw = this_cpu_cfhw();
        if (!cpuhw)
                return;

        /* counter authorization change alert */
        if (alert & CPU_MF_INT_CF_CACA)
                qctri(&cpumf_ctr_info);

        /* loss of counter data alert */
        if (alert & CPU_MF_INT_CF_LCDA)
                pr_err("CPU[%i] Counter data was lost\n", smp_processor_id());

        /* loss of MT counter data alert */
        if (alert & CPU_MF_INT_CF_MTDA)
                pr_warn("CPU[%i] MT counter data was lost\n",
                        smp_processor_id());
}

static int cfset_init(void);
static int __init cpumf_pmu_init(void)
{
        int rc;

        /* Extract counter measurement facility information */
        if (!cpum_cf_avail() || qctri(&cpumf_ctr_info))
                return -ENODEV;

        /* Determine and store counter set sizes for later reference */
        for (rc = CPUMF_CTR_SET_BASIC; rc < CPUMF_CTR_SET_MAX; ++rc)
                cpum_cf_make_setsize(rc);

        /*
         * Clear bit 15 of cr0 to unauthorize problem-state to
         * extract measurement counters
         */
        system_ctl_clear_bit(0, CR0_CPUMF_EXTRACTION_AUTH_BIT);

        /* register handler for measurement-alert interruptions */
        rc = register_external_irq(EXT_IRQ_MEASURE_ALERT,
                                   cpumf_measurement_alert);
        if (rc) {
                pr_err("Registering for CPU-measurement alerts failed with rc=%i\n", rc);
                return rc;
        }

        /* Setup s390dbf facility */
        cf_dbg = debug_register(KMSG_COMPONENT, 2, 1, 128);
        if (!cf_dbg) {
                pr_err("Registration of s390dbf(cpum_cf) failed\n");
                rc = -ENOMEM;
                goto out1;
        }
        debug_register_view(cf_dbg, &debug_sprintf_view);

        cpumf_pmu.attr_groups = cpumf_cf_event_group();
        rc = perf_pmu_register(&cpumf_pmu, "cpum_cf", -1);
        if (rc) {
                pr_err("Registering the cpum_cf PMU failed with rc=%i\n", rc);
                goto out2;
        } else if (stccm_avail()) {     /* Setup counter set device */
                cfset_init();
        }

        rc = cpuhp_setup_state(CPUHP_AP_PERF_S390_CF_ONLINE,
                               "perf/s390/cf:online",
                               cpum_cf_online_cpu, cpum_cf_offline_cpu);
        return rc;

out2:
        debug_unregister_view(cf_dbg, &debug_sprintf_view);
        debug_unregister(cf_dbg);
out1:
        unregister_external_irq(EXT_IRQ_MEASURE_ALERT, cpumf_measurement_alert);
        return rc;
}

/* Support for the CPU Measurement Facility counter set extraction using
 * device /dev/hwctr. This allows user space programs to extract complete
 * counter set via normal file operations.
 */

struct cfset_call_on_cpu_parm {         /* Parm struct for smp_call_on_cpu */
        unsigned int sets;              /* Counter set bit mask */
        atomic_t cpus_ack;              /* # CPUs successfully executed func */
};

struct cfset_request {                  /* CPUs and counter set bit mask */
        unsigned long ctrset;           /* Bit mask of counter set to read */
        cpumask_t mask;                 /* CPU mask to read from */
        struct list_head node;          /* Chain to cfset_session.head */
};

static void cfset_session_init(void)
{
        INIT_LIST_HEAD(&cfset_session.head);
}

/* Remove current request from global bookkeeping. Maintain a counter set bit
 * mask on a per CPU basis.
 * Done in process context under mutex protection.
 */
static void cfset_session_del(struct cfset_request *p)
{
        list_del(&p->node);
}

/* Add current request to global bookkeeping. Maintain a counter set bit mask
 * on a per CPU basis.
 * Done in process context under mutex protection.
 */
static void cfset_session_add(struct cfset_request *p)
{
        list_add(&p->node, &cfset_session.head);
}

/* The /dev/hwctr device access uses PMU_F_IN_USE to mark the device access
 * path is currently used.
 * The cpu_cf_events::dev_state is used to denote counter sets in use by this
 * interface. It is always or'ed in. If this interface is not active, its
 * value is zero and no additional counter sets will be included.
 *
 * The cpu_cf_events::state is used by the perf_event_open SVC and remains
 * unchanged.
 *
 * perf_pmu_enable() and perf_pmu_enable() and its call backs
 * cpumf_pmu_enable() and  cpumf_pmu_disable() are called by the
 * performance measurement subsystem to enable per process
 * CPU Measurement counter facility.
 * The XXX_enable() and XXX_disable functions are used to turn off
 * x86 performance monitoring interrupt (PMI) during scheduling.
 * s390 uses these calls to temporarily stop and resume the active CPU
 * counters sets during scheduling.
 *
 * We do allow concurrent access of perf_event_open() SVC and /dev/hwctr
 * device access.  The perf_event_open() SVC interface makes a lot of effort
 * to only run the counters while the calling process is actively scheduled
 * to run.
 * When /dev/hwctr interface is also used at the same time, the counter sets
 * will keep running, even when the process is scheduled off a CPU.
 * However this is not a problem and does not lead to wrong counter values
 * for the perf_event_open() SVC. The current counter value will be recorded
 * during schedule-in. At schedule-out time the current counter value is
 * extracted again and the delta is calculated and added to the event.
 */
/* Stop all counter sets via ioctl interface */
static void cfset_ioctl_off(void *parm)
{
        struct cpu_cf_events *cpuhw = this_cpu_cfhw();
        struct cfset_call_on_cpu_parm *p = parm;
        int rc;

        /* Check if any counter set used by /dev/hwctr */
        for (rc = CPUMF_CTR_SET_BASIC; rc < CPUMF_CTR_SET_MAX; ++rc)
                if ((p->sets & cpumf_ctr_ctl[rc])) {
                        if (!atomic_dec_return(&cpuhw->ctr_set[rc])) {
                                ctr_set_disable(&cpuhw->dev_state,
                                                cpumf_ctr_ctl[rc]);
                                ctr_set_stop(&cpuhw->dev_state,
                                             cpumf_ctr_ctl[rc]);
                        }
                }
        /* Keep perf_event_open counter sets */
        rc = lcctl(cpuhw->dev_state | cpuhw->state);
        if (rc)
                pr_err("Counter set stop %#llx of /dev/%s failed rc=%i\n",
                       cpuhw->state, S390_HWCTR_DEVICE, rc);
        if (!cpuhw->dev_state)
                cpuhw->flags &= ~PMU_F_IN_USE;
}

/* Start counter sets on particular CPU */
static void cfset_ioctl_on(void *parm)
{
        struct cpu_cf_events *cpuhw = this_cpu_cfhw();
        struct cfset_call_on_cpu_parm *p = parm;
        int rc;

        cpuhw->flags |= PMU_F_IN_USE;
        ctr_set_enable(&cpuhw->dev_state, p->sets);
        ctr_set_start(&cpuhw->dev_state, p->sets);
        for (rc = CPUMF_CTR_SET_BASIC; rc < CPUMF_CTR_SET_MAX; ++rc)
                if ((p->sets & cpumf_ctr_ctl[rc]))
                        atomic_inc(&cpuhw->ctr_set[rc]);
        rc = lcctl(cpuhw->dev_state | cpuhw->state);    /* Start counter sets */
        if (!rc)
                atomic_inc(&p->cpus_ack);
        else
                pr_err("Counter set start %#llx of /dev/%s failed rc=%i\n",
                       cpuhw->dev_state | cpuhw->state, S390_HWCTR_DEVICE, rc);
}

static void cfset_release_cpu(void *p)
{
        struct cpu_cf_events *cpuhw = this_cpu_cfhw();
        int rc;

        cpuhw->dev_state = 0;
        rc = lcctl(cpuhw->state);       /* Keep perf_event_open counter sets */
        if (rc)
                pr_err("Counter set release %#llx of /dev/%s failed rc=%i\n",
                       cpuhw->state, S390_HWCTR_DEVICE, rc);
}

/* This modifies the process CPU mask to adopt it to the currently online
 * CPUs. Offline CPUs can not be addresses. This call terminates the access
 * and is usually followed by close() or a new iotcl(..., START, ...) which
 * creates a new request structure.
 */
static void cfset_all_stop(struct cfset_request *req)
{
        struct cfset_call_on_cpu_parm p = {
                .sets = req->ctrset,
        };

        cpumask_and(&req->mask, &req->mask, cpu_online_mask);
        on_each_cpu_mask(&req->mask, cfset_ioctl_off, &p, 1);
}

/* Release function is also called when application gets terminated without
 * doing a proper ioctl(..., S390_HWCTR_STOP, ...) command.
 */
static int cfset_release(struct inode *inode, struct file *file)
{
        mutex_lock(&cfset_ctrset_mutex);
        /* Open followed by close/exit has no private_data */
        if (file->private_data) {
                cfset_all_stop(file->private_data);
                cfset_session_del(file->private_data);
                kfree(file->private_data);
                file->private_data = NULL;
        }
        if (refcount_dec_and_test(&cfset_opencnt)) {    /* Last close */
                on_each_cpu(cfset_release_cpu, NULL, 1);
                cpum_cf_free(-1);
        }
        mutex_unlock(&cfset_ctrset_mutex);
        return 0;
}

/*
 * Open via /dev/hwctr device. Allocate all per CPU resources on the first
 * open of the device. The last close releases all per CPU resources.
 * Parallel perf_event_open system calls also use per CPU resources.
 * These invocations are handled via reference counting on the per CPU data
 * structures.
 */
static int cfset_open(struct inode *inode, struct file *file)
{
        int rc = 0;

        if (!perfmon_capable())
                return -EPERM;
        file->private_data = NULL;

        mutex_lock(&cfset_ctrset_mutex);
        if (!refcount_inc_not_zero(&cfset_opencnt)) {   /* First open */
                rc = cpum_cf_alloc(-1);
                if (!rc) {
                        cfset_session_init();
                        refcount_set(&cfset_opencnt, 1);
                }
        }
        mutex_unlock(&cfset_ctrset_mutex);

        /* nonseekable_open() never fails */
        return rc ?: nonseekable_open(inode, file);
}

static int cfset_all_start(struct cfset_request *req)
{
        struct cfset_call_on_cpu_parm p = {
                .sets = req->ctrset,
                .cpus_ack = ATOMIC_INIT(0),
        };
        cpumask_var_t mask;
        int rc = 0;

        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
                return -ENOMEM;
        cpumask_and(mask, &req->mask, cpu_online_mask);
        on_each_cpu_mask(mask, cfset_ioctl_on, &p, 1);
        if (atomic_read(&p.cpus_ack) != cpumask_weight(mask)) {
                on_each_cpu_mask(mask, cfset_ioctl_off, &p, 1);
                rc = -EIO;
        }
        free_cpumask_var(mask);
        return rc;
}

/* Return the maximum required space for all possible CPUs in case one
 * CPU will be onlined during the START, READ, STOP cycles.
 * To find out the size of the counter sets, any one CPU will do. They
 * all have the same counter sets.
 */
static size_t cfset_needspace(unsigned int sets)
{
        size_t bytes = 0;
        int i;

        for (i = CPUMF_CTR_SET_BASIC; i < CPUMF_CTR_SET_MAX; ++i) {
                if (!(sets & cpumf_ctr_ctl[i]))
                        continue;
                bytes += cpum_cf_read_setsize(i) * sizeof(u64) +
                         sizeof(((struct s390_ctrset_setdata *)0)->set) +
                         sizeof(((struct s390_ctrset_setdata *)0)->no_cnts);
        }
        bytes = sizeof(((struct s390_ctrset_read *)0)->no_cpus) + nr_cpu_ids *
                (bytes + sizeof(((struct s390_ctrset_cpudata *)0)->cpu_nr) +
                     sizeof(((struct s390_ctrset_cpudata *)0)->no_sets));
        return bytes;
}

static int cfset_all_copy(unsigned long arg, cpumask_t *mask)
{
        struct s390_ctrset_read __user *ctrset_read;
        unsigned int cpu, cpus, rc = 0;
        void __user *uptr;

        ctrset_read = (struct s390_ctrset_read __user *)arg;
        uptr = ctrset_read->data;
        for_each_cpu(cpu, mask) {
                struct cpu_cf_events *cpuhw = get_cpu_cfhw(cpu);
                struct s390_ctrset_cpudata __user *ctrset_cpudata;

                ctrset_cpudata = uptr;
                rc  = put_user(cpu, &ctrset_cpudata->cpu_nr);
                rc |= put_user(cpuhw->sets, &ctrset_cpudata->no_sets);
                rc |= copy_to_user(ctrset_cpudata->data, cpuhw->data,
                                   cpuhw->used);
                if (rc) {
                        rc = -EFAULT;
                        goto out;
                }
                uptr += sizeof(struct s390_ctrset_cpudata) + cpuhw->used;
                cond_resched();
        }
        cpus = cpumask_weight(mask);
        if (put_user(cpus, &ctrset_read->no_cpus))
                rc = -EFAULT;
out:
        return rc;
}

static size_t cfset_cpuset_read(struct s390_ctrset_setdata *p, int ctrset,
                                int ctrset_size, size_t room)
{
        size_t need = 0;
        int rc = -1;

        need = sizeof(*p) + sizeof(u64) * ctrset_size;
        if (need <= room) {
                p->set = cpumf_ctr_ctl[ctrset];
                p->no_cnts = ctrset_size;
                rc = ctr_stcctm(ctrset, ctrset_size, (u64 *)p->cv);
                if (rc == 3)            /* Nothing stored */
                        need = 0;
        }
        return need;
}

/* Read all counter sets. */
static void cfset_cpu_read(void *parm)
{
        struct cpu_cf_events *cpuhw = this_cpu_cfhw();
        struct cfset_call_on_cpu_parm *p = parm;
        int set, set_size;
        size_t space;

        /* No data saved yet */
        cpuhw->used = 0;
        cpuhw->sets = 0;
        memset(cpuhw->data, 0, sizeof(cpuhw->data));

        /* Scan the counter sets */
        for (set = CPUMF_CTR_SET_BASIC; set < CPUMF_CTR_SET_MAX; ++set) {
                struct s390_ctrset_setdata *sp = (void *)cpuhw->data +
                                                 cpuhw->used;

                if (!(p->sets & cpumf_ctr_ctl[set]))
                        continue;       /* Counter set not in list */
                set_size = cpum_cf_read_setsize(set);
                space = sizeof(cpuhw->data) - cpuhw->used;
                space = cfset_cpuset_read(sp, set, set_size, space);
                if (space) {
                        cpuhw->used += space;
                        cpuhw->sets += 1;
                }
        }
}

static int cfset_all_read(unsigned long arg, struct cfset_request *req)
{
        struct cfset_call_on_cpu_parm p;
        cpumask_var_t mask;
        int rc;

        if (!alloc_cpumask_var(&mask, GFP_KERNEL))
                return -ENOMEM;

        p.sets = req->ctrset;
        cpumask_and(mask, &req->mask, cpu_online_mask);
        on_each_cpu_mask(mask, cfset_cpu_read, &p, 1);
        rc = cfset_all_copy(arg, mask);
        free_cpumask_var(mask);
        return rc;
}

static long cfset_ioctl_read(unsigned long arg, struct cfset_request *req)
{
        int ret = -ENODATA;

        if (req && req->ctrset)
                ret = cfset_all_read(arg, req);
        return ret;
}

static long cfset_ioctl_stop(struct file *file)
{
        struct cfset_request *req = file->private_data;
        int ret = -ENXIO;

        if (req) {
                cfset_all_stop(req);
                cfset_session_del(req);
                kfree(req);
                file->private_data = NULL;
                ret = 0;
        }
        return ret;
}

static long cfset_ioctl_start(unsigned long arg, struct file *file)
{
        struct s390_ctrset_start __user *ustart;
        struct s390_ctrset_start start;
        struct cfset_request *preq;
        void __user *umask;
        unsigned int len;
        int ret = 0;
        size_t need;

        if (file->private_data)
                return -EBUSY;
        ustart = (struct s390_ctrset_start __user *)arg;
        if (copy_from_user(&start, ustart, sizeof(start)))
                return -EFAULT;
        if (start.version != S390_HWCTR_START_VERSION)
                return -EINVAL;
        if (start.counter_sets & ~(cpumf_ctr_ctl[CPUMF_CTR_SET_BASIC] |
                                   cpumf_ctr_ctl[CPUMF_CTR_SET_USER] |
                                   cpumf_ctr_ctl[CPUMF_CTR_SET_CRYPTO] |
                                   cpumf_ctr_ctl[CPUMF_CTR_SET_EXT] |
                                   cpumf_ctr_ctl[CPUMF_CTR_SET_MT_DIAG]))
                return -EINVAL;         /* Invalid counter set */
        if (!start.counter_sets)
                return -EINVAL;         /* No counter set at all? */

        preq = kzalloc(sizeof(*preq), GFP_KERNEL);
        if (!preq)
                return -ENOMEM;
        cpumask_clear(&preq->mask);
        len = min_t(u64, start.cpumask_len, cpumask_size());
        umask = (void __user *)start.cpumask;
        if (copy_from_user(&preq->mask, umask, len)) {
                kfree(preq);
                return -EFAULT;
        }
        if (cpumask_empty(&preq->mask)) {
                kfree(preq);
                return -EINVAL;
        }
        need = cfset_needspace(start.counter_sets);
        if (put_user(need, &ustart->data_bytes)) {
                kfree(preq);
                return -EFAULT;
        }
        preq->ctrset = start.counter_sets;
        ret = cfset_all_start(preq);
        if (!ret) {
                cfset_session_add(preq);
                file->private_data = preq;
        } else {
                kfree(preq);
        }
        return ret;
}

/* Entry point to the /dev/hwctr device interface.
 * The ioctl system call supports three subcommands:
 * S390_HWCTR_START: Start the specified counter sets on a CPU list. The
 *    counter set keeps running until explicitly stopped. Returns the number
 *    of bytes needed to store the counter values. If another S390_HWCTR_START
 *    ioctl subcommand is called without a previous S390_HWCTR_STOP stop
 *    command on the same file descriptor, -EBUSY is returned.
 * S390_HWCTR_READ: Read the counter set values from specified CPU list given
 *    with the S390_HWCTR_START command.
 * S390_HWCTR_STOP: Stops the counter sets on the CPU list given with the
 *    previous S390_HWCTR_START subcommand.
 */
static long cfset_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        int ret;

        cpus_read_lock();
        mutex_lock(&cfset_ctrset_mutex);
        switch (cmd) {
        case S390_HWCTR_START:
                ret = cfset_ioctl_start(arg, file);
                break;
        case S390_HWCTR_STOP:
                ret = cfset_ioctl_stop(file);
                break;
        case S390_HWCTR_READ:
                ret = cfset_ioctl_read(arg, file->private_data);
                break;
        default:
                ret = -ENOTTY;
                break;
        }
        mutex_unlock(&cfset_ctrset_mutex);
        cpus_read_unlock();
        return ret;
}

static const struct file_operations cfset_fops = {
        .owner = THIS_MODULE,
        .open = cfset_open,
        .release = cfset_release,
        .unlocked_ioctl = cfset_ioctl,
        .compat_ioctl = cfset_ioctl,
        .llseek = no_llseek
};

static struct miscdevice cfset_dev = {
        .name   = S390_HWCTR_DEVICE,
        .minor  = MISC_DYNAMIC_MINOR,
        .fops   = &cfset_fops,
        .mode   = 0666,
};

/* Hotplug add of a CPU. Scan through all active processes and add
 * that CPU to the list of CPUs supplied with ioctl(..., START, ...).
 */
static int cfset_online_cpu(unsigned int cpu)
{
        struct cfset_call_on_cpu_parm p;
        struct cfset_request *rp;

        if (!list_empty(&cfset_session.head)) {
                list_for_each_entry(rp, &cfset_session.head, node) {
                        p.sets = rp->ctrset;
                        cfset_ioctl_on(&p);
                        cpumask_set_cpu(cpu, &rp->mask);
                }
        }
        return 0;
}

/* Hotplug remove of a CPU. Scan through all active processes and clear
 * that CPU from the list of CPUs supplied with ioctl(..., START, ...).
 * Adjust reference counts.
 */
static int cfset_offline_cpu(unsigned int cpu)
{
        struct cfset_call_on_cpu_parm p;
        struct cfset_request *rp;

        if (!list_empty(&cfset_session.head)) {
                list_for_each_entry(rp, &cfset_session.head, node) {
                        p.sets = rp->ctrset;
                        cfset_ioctl_off(&p);
                        cpumask_clear_cpu(cpu, &rp->mask);
                }
        }
        return 0;
}

static void cfdiag_read(struct perf_event *event)
{
}

static int get_authctrsets(void)
{
        unsigned long auth = 0;
        enum cpumf_ctr_set i;

        for (i = CPUMF_CTR_SET_BASIC; i < CPUMF_CTR_SET_MAX; ++i) {
                if (cpumf_ctr_info.auth_ctl & cpumf_ctr_ctl[i])
                        auth |= cpumf_ctr_ctl[i];
        }
        return auth;
}

/* Setup the event. Test for authorized counter sets and only include counter
 * sets which are authorized at the time of the setup. Including unauthorized
 * counter sets result in specification exception (and panic).
 */
static int cfdiag_event_init2(struct perf_event *event)
{
        struct perf_event_attr *attr = &event->attr;
        int err = 0;

        /* Set sample_period to indicate sampling */
        event->hw.config = attr->config;
        event->hw.sample_period = attr->sample_period;
        local64_set(&event->hw.period_left, event->hw.sample_period);
        local64_set(&event->count, 0);
        event->hw.last_period = event->hw.sample_period;

        /* Add all authorized counter sets to config_base. The
         * the hardware init function is either called per-cpu or just once
         * for all CPUS (event->cpu == -1).  This depends on the whether
         * counting is started for all CPUs or on a per workload base where
         * the perf event moves from one CPU to another CPU.
         * Checking the authorization on any CPU is fine as the hardware
         * applies the same authorization settings to all CPUs.
         */
        event->hw.config_base = get_authctrsets();

        /* No authorized counter sets, nothing to count/sample */
        if (!event->hw.config_base)
                err = -EINVAL;

        return err;
}

static int cfdiag_event_init(struct perf_event *event)
{
        struct perf_event_attr *attr = &event->attr;
        int err = -ENOENT;

        if (event->attr.config != PERF_EVENT_CPUM_CF_DIAG ||
            event->attr.type != event->pmu->type)
                goto out;

        /* Raw events are used to access counters directly,
         * hence do not permit excludes.
         * This event is useless without PERF_SAMPLE_RAW to return counter set
         * values as raw data.
         */
        if (attr->exclude_kernel || attr->exclude_user || attr->exclude_hv ||
            !(attr->sample_type & (PERF_SAMPLE_CPU | PERF_SAMPLE_RAW))) {
                err = -EOPNOTSUPP;
                goto out;
        }

        /* Initialize for using the CPU-measurement counter facility */
        if (cpum_cf_alloc(event->cpu))
                return -ENOMEM;
        event->destroy = hw_perf_event_destroy;

        err = cfdiag_event_init2(event);
        if (unlikely(err))
                event->destroy(event);
out:
        return err;
}

/* Create cf_diag/events/CF_DIAG event sysfs file. This counter is used
 * to collect the complete counter sets for a scheduled process. Target
 * are complete counter sets attached as raw data to the artificial event.
 * This results in complete counter sets available when a process is
 * scheduled. Contains the delta of every counter while the process was
 * running.
 */
CPUMF_EVENT_ATTR(CF_DIAG, CF_DIAG, PERF_EVENT_CPUM_CF_DIAG);

static struct attribute *cfdiag_events_attr[] = {
        CPUMF_EVENT_PTR(CF_DIAG, CF_DIAG),
        NULL,
};

PMU_FORMAT_ATTR(event, "config:0-63");

static struct attribute *cfdiag_format_attr[] = {
        &format_attr_event.attr,
        NULL,
};

static struct attribute_group cfdiag_events_group = {
        .name = "events",
        .attrs = cfdiag_events_attr,
};
static struct attribute_group cfdiag_format_group = {
        .name = "format",
        .attrs = cfdiag_format_attr,
};
static const struct attribute_group *cfdiag_attr_groups[] = {
        &cfdiag_events_group,
        &cfdiag_format_group,
        NULL,
};

/* Performance monitoring unit for event CF_DIAG. Since this event
 * is also started and stopped via the perf_event_open() system call, use
 * the same event enable/disable call back functions. They do not
 * have a pointer to the perf_event strcture as first parameter.
 *
 * The functions XXX_add, XXX_del, XXX_start and XXX_stop are also common.
 * Reuse them and distinguish the event (always first parameter) via
 * 'config' member.
 */
static struct pmu cf_diag = {
        .task_ctx_nr  = perf_sw_context,
        .event_init   = cfdiag_event_init,
        .pmu_enable   = cpumf_pmu_enable,
        .pmu_disable  = cpumf_pmu_disable,
        .add          = cpumf_pmu_add,
        .del          = cpumf_pmu_del,
        .start        = cpumf_pmu_start,
        .stop         = cpumf_pmu_stop,
        .read         = cfdiag_read,

        .attr_groups  = cfdiag_attr_groups
};

/* Calculate memory needed to store all counter sets together with header and
 * trailer data. This is independent of the counter set authorization which
 * can vary depending on the configuration.
 */
static size_t cfdiag_maxsize(struct cpumf_ctr_info *info)
{
        size_t max_size = sizeof(struct cf_trailer_entry);
        enum cpumf_ctr_set i;

        for (i = CPUMF_CTR_SET_BASIC; i < CPUMF_CTR_SET_MAX; ++i) {
                size_t size = cpum_cf_read_setsize(i);

                if (size)
                        max_size += size * sizeof(u64) +
                                    sizeof(struct cf_ctrset_entry);
        }
        return max_size;
}

/* Get the CPU speed, try sampling facility first and CPU attributes second. */
static void cfdiag_get_cpu_speed(void)
{
        unsigned long mhz;

        if (cpum_sf_avail()) {                  /* Sampling facility first */
                struct hws_qsi_info_block si;

                memset(&si, 0, sizeof(si));
                if (!qsi(&si)) {
                        cfdiag_cpu_speed = si.cpu_speed;
                        return;
                }
        }

        /* Fallback: CPU speed extract static part. Used in case
         * CPU Measurement Sampling Facility is turned off.
         */
        mhz = __ecag(ECAG_CPU_ATTRIBUTE, 0);
        if (mhz != -1UL)
                cfdiag_cpu_speed = mhz & 0xffffffff;
}

static int cfset_init(void)
{
        size_t need;
        int rc;

        cfdiag_get_cpu_speed();
        /* Make sure the counter set data fits into predefined buffer. */
        need = cfdiag_maxsize(&cpumf_ctr_info);
        if (need > sizeof(((struct cpu_cf_events *)0)->start)) {
                pr_err("Insufficient memory for PMU(cpum_cf_diag) need=%zu\n",
                       need);
                return -ENOMEM;
        }

        rc = misc_register(&cfset_dev);
        if (rc) {
                pr_err("Registration of /dev/%s failed rc=%i\n",
                       cfset_dev.name, rc);
                goto out;
        }

        rc = perf_pmu_register(&cf_diag, "cpum_cf_diag", -1);
        if (rc) {
                misc_deregister(&cfset_dev);
                pr_err("Registration of PMU(cpum_cf_diag) failed with rc=%i\n",
                       rc);
        }
out:
        return rc;
}

device_initcall(cpumf_pmu_init);