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/gfp.h>
  29 #include <linux/highmem.h>
  30 #include <linux/mutex.h>
  31 #include <linux/refcount.h>
  32 #include <linux/sched/signal.h>
  33 #include <linux/slab.h>
  34 #include <linux/spinlock.h>
  35 #include <linux/wait.h>
  36 #include <linux/workqueue.h>
  37
  38 __noreturn void rust_helper_BUG(void)
  39 {
  40         BUG();
  41 }
  42 EXPORT_SYMBOL_GPL(rust_helper_BUG);
  43
  44 unsigned long rust_helper_copy_from_user(void *to, const void __user *from,
  45                                          unsigned long n)
  46 {
  47         return copy_from_user(to, from, n);
  48 }
  49 EXPORT_SYMBOL_GPL(rust_helper_copy_from_user);
  50
  51 unsigned long rust_helper_copy_to_user(void __user *to, const void *from,
  52                                        unsigned long n)
  53 {
  54         return copy_to_user(to, from, n);
  55 }
  56 EXPORT_SYMBOL_GPL(rust_helper_copy_to_user);
  57
  58 void rust_helper_mutex_lock(struct mutex *lock)
  59 {
  60         mutex_lock(lock);
  61 }
  62 EXPORT_SYMBOL_GPL(rust_helper_mutex_lock);
  63
  64 void rust_helper___spin_lock_init(spinlock_t *lock, const char *name,
  65                                   struct lock_class_key *key)
  66 {
  67 #ifdef CONFIG_DEBUG_SPINLOCK
  68         __raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG);
  69 #else
  70         spin_lock_init(lock);
  71 #endif
  72 }
  73 EXPORT_SYMBOL_GPL(rust_helper___spin_lock_init);
  74
  75 void rust_helper_spin_lock(spinlock_t *lock)
  76 {
  77         spin_lock(lock);
  78 }
  79 EXPORT_SYMBOL_GPL(rust_helper_spin_lock);
  80
  81 void rust_helper_spin_unlock(spinlock_t *lock)
  82 {
  83         spin_unlock(lock);
  84 }
  85 EXPORT_SYMBOL_GPL(rust_helper_spin_unlock);
  86
  87 void rust_helper_init_wait(struct wait_queue_entry *wq_entry)
  88 {
  89         init_wait(wq_entry);
  90 }
  91 EXPORT_SYMBOL_GPL(rust_helper_init_wait);
  92
  93 int rust_helper_signal_pending(struct task_struct *t)
  94 {
  95         return signal_pending(t);
  96 }
  97 EXPORT_SYMBOL_GPL(rust_helper_signal_pending);
  98
  99 struct page *rust_helper_alloc_pages(gfp_t gfp_mask, unsigned int order)
 100 {
 101         return alloc_pages(gfp_mask, order);
 102 }
 103 EXPORT_SYMBOL_GPL(rust_helper_alloc_pages);
 104
 105 void *rust_helper_kmap_local_page(struct page *page)
 106 {
 107         return kmap_local_page(page);
 108 }
 109 EXPORT_SYMBOL_GPL(rust_helper_kmap_local_page);
 110
 111 void rust_helper_kunmap_local(const void *addr)
 112 {
 113         kunmap_local(addr);
 114 }
 115 EXPORT_SYMBOL_GPL(rust_helper_kunmap_local);
 116
 117 refcount_t rust_helper_REFCOUNT_INIT(int n)
 118 {
 119         return (refcount_t)REFCOUNT_INIT(n);
 120 }
 121 EXPORT_SYMBOL_GPL(rust_helper_REFCOUNT_INIT);
 122
 123 void rust_helper_refcount_inc(refcount_t *r)
 124 {
 125         refcount_inc(r);
 126 }
 127 EXPORT_SYMBOL_GPL(rust_helper_refcount_inc);
 128
 129 bool rust_helper_refcount_dec_and_test(refcount_t *r)
 130 {
 131         return refcount_dec_and_test(r);
 132 }
 133 EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test);
 134
 135 __force void *rust_helper_ERR_PTR(long err)
 136 {
 137         return ERR_PTR(err);
 138 }
 139 EXPORT_SYMBOL_GPL(rust_helper_ERR_PTR);
 140
 141 bool rust_helper_IS_ERR(__force const void *ptr)
 142 {
 143         return IS_ERR(ptr);
 144 }
 145 EXPORT_SYMBOL_GPL(rust_helper_IS_ERR);
 146
 147 long rust_helper_PTR_ERR(__force const void *ptr)
 148 {
 149         return PTR_ERR(ptr);
 150 }
 151 EXPORT_SYMBOL_GPL(rust_helper_PTR_ERR);
 152
 153 const char *rust_helper_errname(int err)
 154 {
 155         return errname(err);
 156 }
 157 EXPORT_SYMBOL_GPL(rust_helper_errname);
 158
 159 struct task_struct *rust_helper_get_current(void)
 160 {
 161         return current;
 162 }
 163 EXPORT_SYMBOL_GPL(rust_helper_get_current);
 164
 165 void rust_helper_get_task_struct(struct task_struct *t)
 166 {
 167         get_task_struct(t);
 168 }
 169 EXPORT_SYMBOL_GPL(rust_helper_get_task_struct);
 170
 171 void rust_helper_put_task_struct(struct task_struct *t)
 172 {
 173         put_task_struct(t);
 174 }
 175 EXPORT_SYMBOL_GPL(rust_helper_put_task_struct);
 176
 177 struct kunit *rust_helper_kunit_get_current_test(void)
 178 {
 179         return kunit_get_current_test();
 180 }
 181 EXPORT_SYMBOL_GPL(rust_helper_kunit_get_current_test);
 182
 183 void rust_helper_init_work_with_key(struct work_struct *work, work_func_t func,
 184                                     bool onstack, const char *name,
 185                                     struct lock_class_key *key)
 186 {
 187         __init_work(work, onstack);
 188         work->data = (atomic_long_t)WORK_DATA_INIT();
 189         lockdep_init_map(&work->lockdep_map, name, key, 0);
 190         INIT_LIST_HEAD(&work->entry);
 191         work->func = func;
 192 }
 193 EXPORT_SYMBOL_GPL(rust_helper_init_work_with_key);
 194
 195 void * __must_check __realloc_size(2)
 196 rust_helper_krealloc(const void *objp, size_t new_size, gfp_t flags)
 197 {
 198         return krealloc(objp, new_size, flags);
 199 }
 200 EXPORT_SYMBOL_GPL(rust_helper_krealloc);
 201
 202 /*
 203  * `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
 204  * use it in contexts where Rust expects a `usize` like slice (array) indices.
 205  * `usize` is defined to be the same as C's `uintptr_t` type (can hold any
 206  * pointer) but not necessarily the same as `size_t` (can hold the size of any
 207  * single object). Most modern platforms use the same concrete integer type for
 208  * both of them, but in case we find ourselves on a platform where
 209  * that's not true, fail early instead of risking ABI or
 210  * integer-overflow issues.
 211  *
 212  * If your platform fails this assertion, it means that you are in
 213  * danger of integer-overflow bugs (even if you attempt to add
 214  * `--no-size_t-is-usize`). It may be easiest to change the kernel ABI on
 215  * your platform such that `size_t` matches `uintptr_t` (i.e., to increase
 216  * `size_t`, because `uintptr_t` has to be at least as big as `size_t`).
 217  */
 218 static_assert(
 219         sizeof(size_t) == sizeof(uintptr_t) &&
 220         __alignof__(size_t) == __alignof__(uintptr_t),
 221         "Rust code expects C `size_t` to match Rust `usize`"
 222 );