rust/helpers.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Non-trivial C macros cannot be used in Rust. Similarly, inlined C functions
   4  * cannot be called either. This file explicitly creates functions ("helpers")
   5  * that wrap those so that they can be called from Rust.
   6  *
   7  * Even though Rust kernel modules should never use directly the bindings, some
   8  * of these helpers need to be exported because Rust generics and inlined
   9  * functions may not get their code generated in the crate where they are
  10  * defined. Other helpers, called from non-inline functions, may not be
  11  * exported, in principle. However, in general, the Rust compiler does not
  12  * guarantee codegen will be performed for a non-inline function either.
  13  * Therefore, this file exports all the helpers. In the future, this may be
  14  * revisited to reduce the number of exports after the compiler is informed
  15  * about the places codegen is required.
  16  *
  17  * All symbols are exported as GPL-only to guarantee no GPL-only feature is
  18  * accidentally exposed.
  19  *
  20  * Sorted alphabetically.
  21  */
  22
  23 #include <kunit/test-bug.h>
  24 #include <linux/bug.h>
  25 #include <linux/build_bug.h>
  26 #include <linux/err.h>
  27 #include <linux/errname.h>
  28 #include <linux/mutex.h>
  29 #include <linux/refcount.h>
  30 #include <linux/sched/signal.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/wait.h>
  33 #include <linux/workqueue.h>
  34
  35 __noreturn void rust_helper_BUG(void)
  36 {
  37         BUG();
  38 }
  39 EXPORT_SYMBOL_GPL(rust_helper_BUG);
  40
  41 void rust_helper_mutex_lock(struct mutex *lock)
  42 {
  43         mutex_lock(lock);
  44 }
  45 EXPORT_SYMBOL_GPL(rust_helper_mutex_lock);
  46
  47 void rust_helper___spin_lock_init(spinlock_t *lock, const char *name,
  48                                   struct lock_class_key *key)
  49 {
  50 #ifdef CONFIG_DEBUG_SPINLOCK
  51         __raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG);
  52 #else
  53         spin_lock_init(lock);
  54 #endif
  55 }
  56 EXPORT_SYMBOL_GPL(rust_helper___spin_lock_init);
  57
  58 void rust_helper_spin_lock(spinlock_t *lock)
  59 {
  60         spin_lock(lock);
  61 }
  62 EXPORT_SYMBOL_GPL(rust_helper_spin_lock);
  63
  64 void rust_helper_spin_unlock(spinlock_t *lock)
  65 {
  66         spin_unlock(lock);
  67 }
  68 EXPORT_SYMBOL_GPL(rust_helper_spin_unlock);
  69
  70 void rust_helper_init_wait(struct wait_queue_entry *wq_entry)
  71 {
  72         init_wait(wq_entry);
  73 }
  74 EXPORT_SYMBOL_GPL(rust_helper_init_wait);
  75
  76 int rust_helper_signal_pending(struct task_struct *t)
  77 {
  78         return signal_pending(t);
  79 }
  80 EXPORT_SYMBOL_GPL(rust_helper_signal_pending);
  81
  82 refcount_t rust_helper_REFCOUNT_INIT(int n)
  83 {
  84         return (refcount_t)REFCOUNT_INIT(n);
  85 }
  86 EXPORT_SYMBOL_GPL(rust_helper_REFCOUNT_INIT);
  87
  88 void rust_helper_refcount_inc(refcount_t *r)
  89 {
  90         refcount_inc(r);
  91 }
  92 EXPORT_SYMBOL_GPL(rust_helper_refcount_inc);
  93
  94 bool rust_helper_refcount_dec_and_test(refcount_t *r)
  95 {
  96         return refcount_dec_and_test(r);
  97 }
  98 EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test);
  99
 100 __force void *rust_helper_ERR_PTR(long err)
 101 {
 102         return ERR_PTR(err);
 103 }
 104 EXPORT_SYMBOL_GPL(rust_helper_ERR_PTR);
 105
 106 bool rust_helper_IS_ERR(__force const void *ptr)
 107 {
 108         return IS_ERR(ptr);
 109 }
 110 EXPORT_SYMBOL_GPL(rust_helper_IS_ERR);
 111
 112 long rust_helper_PTR_ERR(__force const void *ptr)
 113 {
 114         return PTR_ERR(ptr);
 115 }
 116 EXPORT_SYMBOL_GPL(rust_helper_PTR_ERR);
 117
 118 const char *rust_helper_errname(int err)
 119 {
 120         return errname(err);
 121 }
 122 EXPORT_SYMBOL_GPL(rust_helper_errname);
 123
 124 struct task_struct *rust_helper_get_current(void)
 125 {
 126         return current;
 127 }
 128 EXPORT_SYMBOL_GPL(rust_helper_get_current);
 129
 130 void rust_helper_get_task_struct(struct task_struct *t)
 131 {
 132         get_task_struct(t);
 133 }
 134 EXPORT_SYMBOL_GPL(rust_helper_get_task_struct);
 135
 136 void rust_helper_put_task_struct(struct task_struct *t)
 137 {
 138         put_task_struct(t);
 139 }
 140 EXPORT_SYMBOL_GPL(rust_helper_put_task_struct);
 141
 142 struct kunit *rust_helper_kunit_get_current_test(void)
 143 {
 144         return kunit_get_current_test();
 145 }
 146 EXPORT_SYMBOL_GPL(rust_helper_kunit_get_current_test);
 147
 148 void rust_helper_init_work_with_key(struct work_struct *work, work_func_t func,
 149                                     bool onstack, const char *name,
 150                                     struct lock_class_key *key)
 151 {
 152         __init_work(work, onstack);
 153         work->data = (atomic_long_t)WORK_DATA_INIT();
 154         lockdep_init_map(&work->lockdep_map, name, key, 0);
 155         INIT_LIST_HEAD(&work->entry);
 156         work->func = func;
 157 }
 158 EXPORT_SYMBOL_GPL(rust_helper_init_work_with_key);
 159
 160 /*
 161  * `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
 162  * use it in contexts where Rust expects a `usize` like slice (array) indices.
 163  * `usize` is defined to be the same as C's `uintptr_t` type (can hold any
 164  * pointer) but not necessarily the same as `size_t` (can hold the size of any
 165  * single object). Most modern platforms use the same concrete integer type for
 166  * both of them, but in case we find ourselves on a platform where
 167  * that's not true, fail early instead of risking ABI or
 168  * integer-overflow issues.
 169  *
 170  * If your platform fails this assertion, it means that you are in
 171  * danger of integer-overflow bugs (even if you attempt to add
 172  * `--no-size_t-is-usize`). It may be easiest to change the kernel ABI on
 173  * your platform such that `size_t` matches `uintptr_t` (i.e., to increase
 174  * `size_t`, because `uintptr_t` has to be at least as big as `size_t`).
 175  */
 176 static_assert(
 177         sizeof(size_t) == sizeof(uintptr_t) &&
 178         __alignof__(size_t) == __alignof__(uintptr_t),
 179         "Rust code expects C `size_t` to match Rust `usize`"
 180 );