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
  34 __noreturn void rust_helper_BUG(void)
  35 {
  36         BUG();
  37 }
  38 EXPORT_SYMBOL_GPL(rust_helper_BUG);
  39
  40 void rust_helper_mutex_lock(struct mutex *lock)
  41 {
  42         mutex_lock(lock);
  43 }
  44 EXPORT_SYMBOL_GPL(rust_helper_mutex_lock);
  45
  46 void rust_helper___spin_lock_init(spinlock_t *lock, const char *name,
  47                                   struct lock_class_key *key)
  48 {
  49 #ifdef CONFIG_DEBUG_SPINLOCK
  50         __raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG);
  51 #else
  52         spin_lock_init(lock);
  53 #endif
  54 }
  55 EXPORT_SYMBOL_GPL(rust_helper___spin_lock_init);
  56
  57 void rust_helper_spin_lock(spinlock_t *lock)
  58 {
  59         spin_lock(lock);
  60 }
  61 EXPORT_SYMBOL_GPL(rust_helper_spin_lock);
  62
  63 void rust_helper_spin_unlock(spinlock_t *lock)
  64 {
  65         spin_unlock(lock);
  66 }
  67 EXPORT_SYMBOL_GPL(rust_helper_spin_unlock);
  68
  69 void rust_helper_init_wait(struct wait_queue_entry *wq_entry)
  70 {
  71         init_wait(wq_entry);
  72 }
  73 EXPORT_SYMBOL_GPL(rust_helper_init_wait);
  74
  75 int rust_helper_signal_pending(struct task_struct *t)
  76 {
  77         return signal_pending(t);
  78 }
  79 EXPORT_SYMBOL_GPL(rust_helper_signal_pending);
  80
  81 refcount_t rust_helper_REFCOUNT_INIT(int n)
  82 {
  83         return (refcount_t)REFCOUNT_INIT(n);
  84 }
  85 EXPORT_SYMBOL_GPL(rust_helper_REFCOUNT_INIT);
  86
  87 void rust_helper_refcount_inc(refcount_t *r)
  88 {
  89         refcount_inc(r);
  90 }
  91 EXPORT_SYMBOL_GPL(rust_helper_refcount_inc);
  92
  93 bool rust_helper_refcount_dec_and_test(refcount_t *r)
  94 {
  95         return refcount_dec_and_test(r);
  96 }
  97 EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test);
  98
  99 __force void *rust_helper_ERR_PTR(long err)
 100 {
 101         return ERR_PTR(err);
 102 }
 103 EXPORT_SYMBOL_GPL(rust_helper_ERR_PTR);
 104
 105 bool rust_helper_IS_ERR(__force const void *ptr)
 106 {
 107         return IS_ERR(ptr);
 108 }
 109 EXPORT_SYMBOL_GPL(rust_helper_IS_ERR);
 110
 111 long rust_helper_PTR_ERR(__force const void *ptr)
 112 {
 113         return PTR_ERR(ptr);
 114 }
 115 EXPORT_SYMBOL_GPL(rust_helper_PTR_ERR);
 116
 117 const char *rust_helper_errname(int err)
 118 {
 119         return errname(err);
 120 }
 121 EXPORT_SYMBOL_GPL(rust_helper_errname);
 122
 123 struct task_struct *rust_helper_get_current(void)
 124 {
 125         return current;
 126 }
 127 EXPORT_SYMBOL_GPL(rust_helper_get_current);
 128
 129 void rust_helper_get_task_struct(struct task_struct *t)
 130 {
 131         get_task_struct(t);
 132 }
 133 EXPORT_SYMBOL_GPL(rust_helper_get_task_struct);
 134
 135 void rust_helper_put_task_struct(struct task_struct *t)
 136 {
 137         put_task_struct(t);
 138 }
 139 EXPORT_SYMBOL_GPL(rust_helper_put_task_struct);
 140
 141 struct kunit *rust_helper_kunit_get_current_test(void)
 142 {
 143         return kunit_get_current_test();
 144 }
 145 EXPORT_SYMBOL_GPL(rust_helper_kunit_get_current_test);
 146
 147 /*
 148  * `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
 149  * use it in contexts where Rust expects a `usize` like slice (array) indices.
 150  * `usize` is defined to be the same as C's `uintptr_t` type (can hold any
 151  * pointer) but not necessarily the same as `size_t` (can hold the size of any
 152  * single object). Most modern platforms use the same concrete integer type for
 153  * both of them, but in case we find ourselves on a platform where
 154  * that's not true, fail early instead of risking ABI or
 155  * integer-overflow issues.
 156  *
 157  * If your platform fails this assertion, it means that you are in
 158  * danger of integer-overflow bugs (even if you attempt to add
 159  * `--no-size_t-is-usize`). It may be easiest to change the kernel ABI on
 160  * your platform such that `size_t` matches `uintptr_t` (i.e., to increase
 161  * `size_t`, because `uintptr_t` has to be at least as big as `size_t`).
 162  */
 163 static_assert(
 164         sizeof(size_t) == sizeof(uintptr_t) &&
 165         __alignof__(size_t) == __alignof__(uintptr_t),
 166         "Rust code expects C `size_t` to match Rust `usize`"
 167 );