xref: /openbmc/linux/rust/helpers.c (revision 08ab7865)
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 
rust_helper_BUG(void)34 __noreturn void rust_helper_BUG(void)
35 {
36 	BUG();
37 }
38 EXPORT_SYMBOL_GPL(rust_helper_BUG);
39 
rust_helper_mutex_lock(struct mutex * lock)40 void rust_helper_mutex_lock(struct mutex *lock)
41 {
42 	mutex_lock(lock);
43 }
44 EXPORT_SYMBOL_GPL(rust_helper_mutex_lock);
45 
rust_helper___spin_lock_init(spinlock_t * lock,const char * name,struct lock_class_key * key)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 
rust_helper_spin_lock(spinlock_t * lock)57 void rust_helper_spin_lock(spinlock_t *lock)
58 {
59 	spin_lock(lock);
60 }
61 EXPORT_SYMBOL_GPL(rust_helper_spin_lock);
62 
rust_helper_spin_unlock(spinlock_t * lock)63 void rust_helper_spin_unlock(spinlock_t *lock)
64 {
65 	spin_unlock(lock);
66 }
67 EXPORT_SYMBOL_GPL(rust_helper_spin_unlock);
68 
rust_helper_init_wait(struct wait_queue_entry * wq_entry)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 
rust_helper_signal_pending(struct task_struct * t)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 
rust_helper_REFCOUNT_INIT(int n)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 
rust_helper_refcount_inc(refcount_t * r)87 void rust_helper_refcount_inc(refcount_t *r)
88 {
89 	refcount_inc(r);
90 }
91 EXPORT_SYMBOL_GPL(rust_helper_refcount_inc);
92 
rust_helper_refcount_dec_and_test(refcount_t * r)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 
rust_helper_ERR_PTR(long err)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 
rust_helper_IS_ERR(__force const void * ptr)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 
rust_helper_PTR_ERR(__force const void * ptr)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 
rust_helper_errname(int err)117 const char *rust_helper_errname(int err)
118 {
119 	return errname(err);
120 }
121 EXPORT_SYMBOL_GPL(rust_helper_errname);
122 
rust_helper_get_current(void)123 struct task_struct *rust_helper_get_current(void)
124 {
125 	return current;
126 }
127 EXPORT_SYMBOL_GPL(rust_helper_get_current);
128 
rust_helper_get_task_struct(struct task_struct * t)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 
rust_helper_put_task_struct(struct task_struct * t)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 
rust_helper_kunit_get_current_test(void)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 );
168