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 the bindings directly, 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/slab.h>
  32 #include <linux/spinlock.h>
  33 #include <linux/wait.h>
  34 #include <linux/workqueue.h>
  35
  36 __noreturn void rust_helper_BUG(void)
  37 {
  38         BUG();
  39 }
  40 EXPORT_SYMBOL_GPL(rust_helper_BUG);
  41
  42 void rust_helper_mutex_lock(struct mutex *lock)
  43 {
  44         mutex_lock(lock);
  45 }
  46 EXPORT_SYMBOL_GPL(rust_helper_mutex_lock);
  47
  48 void rust_helper___spin_lock_init(spinlock_t *lock, const char *name,
  49                                   struct lock_class_key *key)
  50 {
  51 #ifdef CONFIG_DEBUG_SPINLOCK
  52         __raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG);
  53 #else
  54         spin_lock_init(lock);
  55 #endif
  56 }
  57 EXPORT_SYMBOL_GPL(rust_helper___spin_lock_init);
  58
  59 void rust_helper_spin_lock(spinlock_t *lock)
  60 {
  61         spin_lock(lock);
  62 }
  63 EXPORT_SYMBOL_GPL(rust_helper_spin_lock);
  64
  65 void rust_helper_spin_unlock(spinlock_t *lock)
  66 {
  67         spin_unlock(lock);
  68 }
  69 EXPORT_SYMBOL_GPL(rust_helper_spin_unlock);
  70
  71 void rust_helper_init_wait(struct wait_queue_entry *wq_entry)
  72 {
  73         init_wait(wq_entry);
  74 }
  75 EXPORT_SYMBOL_GPL(rust_helper_init_wait);
  76
  77 int rust_helper_signal_pending(struct task_struct *t)
  78 {
  79         return signal_pending(t);
  80 }
  81 EXPORT_SYMBOL_GPL(rust_helper_signal_pending);
  82
  83 refcount_t rust_helper_REFCOUNT_INIT(int n)
  84 {
  85         return (refcount_t)REFCOUNT_INIT(n);
  86 }
  87 EXPORT_SYMBOL_GPL(rust_helper_REFCOUNT_INIT);
  88
  89 void rust_helper_refcount_inc(refcount_t *r)
  90 {
  91         refcount_inc(r);
  92 }
  93 EXPORT_SYMBOL_GPL(rust_helper_refcount_inc);
  94
  95 bool rust_helper_refcount_dec_and_test(refcount_t *r)
  96 {
  97         return refcount_dec_and_test(r);
  98 }
  99 EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test);
 100
 101 __force void *rust_helper_ERR_PTR(long err)
 102 {
 103         return ERR_PTR(err);
 104 }
 105 EXPORT_SYMBOL_GPL(rust_helper_ERR_PTR);
 106
 107 bool rust_helper_IS_ERR(__force const void *ptr)
 108 {
 109         return IS_ERR(ptr);
 110 }
 111 EXPORT_SYMBOL_GPL(rust_helper_IS_ERR);
 112
 113 long rust_helper_PTR_ERR(__force const void *ptr)
 114 {
 115         return PTR_ERR(ptr);
 116 }
 117 EXPORT_SYMBOL_GPL(rust_helper_PTR_ERR);
 118
 119 const char *rust_helper_errname(int err)
 120 {
 121         return errname(err);
 122 }
 123 EXPORT_SYMBOL_GPL(rust_helper_errname);
 124
 125 struct task_struct *rust_helper_get_current(void)
 126 {
 127         return current;
 128 }
 129 EXPORT_SYMBOL_GPL(rust_helper_get_current);
 130
 131 void rust_helper_get_task_struct(struct task_struct *t)
 132 {
 133         get_task_struct(t);
 134 }
 135 EXPORT_SYMBOL_GPL(rust_helper_get_task_struct);
 136
 137 void rust_helper_put_task_struct(struct task_struct *t)
 138 {
 139         put_task_struct(t);
 140 }
 141 EXPORT_SYMBOL_GPL(rust_helper_put_task_struct);
 142
 143 struct kunit *rust_helper_kunit_get_current_test(void)
 144 {
 145         return kunit_get_current_test();
 146 }
 147 EXPORT_SYMBOL_GPL(rust_helper_kunit_get_current_test);
 148
 149 void rust_helper_init_work_with_key(struct work_struct *work, work_func_t func,
 150                                     bool onstack, const char *name,
 151                                     struct lock_class_key *key)
 152 {
 153         __init_work(work, onstack);
 154         work->data = (atomic_long_t)WORK_DATA_INIT();
 155         lockdep_init_map(&work->lockdep_map, name, key, 0);
 156         INIT_LIST_HEAD(&work->entry);
 157         work->func = func;
 158 }
 159 EXPORT_SYMBOL_GPL(rust_helper_init_work_with_key);
 160
 161 void * __must_check __realloc_size(2)
 162 rust_helper_krealloc(const void *objp, size_t new_size, gfp_t flags)
 163 {
 164         return krealloc(objp, new_size, flags);
 165 }
 166 EXPORT_SYMBOL_GPL(rust_helper_krealloc);
 167
 168 /*
 169  * `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
 170  * use it in contexts where Rust expects a `usize` like slice (array) indices.
 171  * `usize` is defined to be the same as C's `uintptr_t` type (can hold any
 172  * pointer) but not necessarily the same as `size_t` (can hold the size of any
 173  * single object). Most modern platforms use the same concrete integer type for
 174  * both of them, but in case we find ourselves on a platform where
 175  * that's not true, fail early instead of risking ABI or
 176  * integer-overflow issues.
 177  *
 178  * If your platform fails this assertion, it means that you are in
 179  * danger of integer-overflow bugs (even if you attempt to add
 180  * `--no-size_t-is-usize`). It may be easiest to change the kernel ABI on
 181  * your platform such that `size_t` matches `uintptr_t` (i.e., to increase
 182  * `size_t`, because `uintptr_t` has to be at least as big as `size_t`).
 183  */
 184 static_assert(
 185         sizeof(size_t) == sizeof(uintptr_t) &&
 186         __alignof__(size_t) == __alignof__(uintptr_t),
 187         "Rust code expects C `size_t` to match Rust `usize`"
 188 );