FreeBSD/Linux Kernel Cross Reference
sys/sys/stdatomic.h
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2011 Ed Schouten <ed@FreeBSD.org>
5 * David Chisnall <theraven@FreeBSD.org>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD$
30 */
31
32 #ifndef _STDATOMIC_H_
33 #define _STDATOMIC_H_
34
35 #include <sys/cdefs.h>
36 #include <sys/_types.h>
37
38 #if __has_extension(c_atomic) || __has_extension(cxx_atomic)
39 #define __CLANG_ATOMICS
40 #elif __GNUC_PREREQ__(4, 7)
41 #define __GNUC_ATOMICS
42 #elif defined(__GNUC__)
43 #define __SYNC_ATOMICS
44 #else
45 #error "stdatomic.h does not support your compiler"
46 #endif
47
48 /*
49 * 7.17.1 Atomic lock-free macros.
50 */
51
52 #ifdef __GCC_ATOMIC_BOOL_LOCK_FREE
53 #define ATOMIC_BOOL_LOCK_FREE __GCC_ATOMIC_BOOL_LOCK_FREE
54 #endif
55 #ifdef __GCC_ATOMIC_CHAR_LOCK_FREE
56 #define ATOMIC_CHAR_LOCK_FREE __GCC_ATOMIC_CHAR_LOCK_FREE
57 #endif
58 #ifdef __GCC_ATOMIC_CHAR16_T_LOCK_FREE
59 #define ATOMIC_CHAR16_T_LOCK_FREE __GCC_ATOMIC_CHAR16_T_LOCK_FREE
60 #endif
61 #ifdef __GCC_ATOMIC_CHAR32_T_LOCK_FREE
62 #define ATOMIC_CHAR32_T_LOCK_FREE __GCC_ATOMIC_CHAR32_T_LOCK_FREE
63 #endif
64 #ifdef __GCC_ATOMIC_WCHAR_T_LOCK_FREE
65 #define ATOMIC_WCHAR_T_LOCK_FREE __GCC_ATOMIC_WCHAR_T_LOCK_FREE
66 #endif
67 #ifdef __GCC_ATOMIC_SHORT_LOCK_FREE
68 #define ATOMIC_SHORT_LOCK_FREE __GCC_ATOMIC_SHORT_LOCK_FREE
69 #endif
70 #ifdef __GCC_ATOMIC_INT_LOCK_FREE
71 #define ATOMIC_INT_LOCK_FREE __GCC_ATOMIC_INT_LOCK_FREE
72 #endif
73 #ifdef __GCC_ATOMIC_LONG_LOCK_FREE
74 #define ATOMIC_LONG_LOCK_FREE __GCC_ATOMIC_LONG_LOCK_FREE
75 #endif
76 #ifdef __GCC_ATOMIC_LLONG_LOCK_FREE
77 #define ATOMIC_LLONG_LOCK_FREE __GCC_ATOMIC_LLONG_LOCK_FREE
78 #endif
79 #ifdef __GCC_ATOMIC_POINTER_LOCK_FREE
80 #define ATOMIC_POINTER_LOCK_FREE __GCC_ATOMIC_POINTER_LOCK_FREE
81 #endif
82
83 /*
84 * 7.17.2 Initialization.
85 */
86
87 #if defined(__CLANG_ATOMICS)
88 #define ATOMIC_VAR_INIT(value) (value)
89 #define atomic_init(obj, value) __c11_atomic_init(obj, value)
90 #else
91 #define ATOMIC_VAR_INIT(value) { .__val = (value) }
92 #define atomic_init(obj, value) ((void)((obj)->__val = (value)))
93 #endif
94
95 /*
96 * Clang and recent GCC both provide predefined macros for the memory
97 * orderings. If we are using a compiler that doesn't define them, use the
98 * clang values - these will be ignored in the fallback path.
99 */
100
101 #ifndef __ATOMIC_RELAXED
102 #define __ATOMIC_RELAXED 0
103 #endif
104 #ifndef __ATOMIC_CONSUME
105 #define __ATOMIC_CONSUME 1
106 #endif
107 #ifndef __ATOMIC_ACQUIRE
108 #define __ATOMIC_ACQUIRE 2
109 #endif
110 #ifndef __ATOMIC_RELEASE
111 #define __ATOMIC_RELEASE 3
112 #endif
113 #ifndef __ATOMIC_ACQ_REL
114 #define __ATOMIC_ACQ_REL 4
115 #endif
116 #ifndef __ATOMIC_SEQ_CST
117 #define __ATOMIC_SEQ_CST 5
118 #endif
119
120 /*
121 * 7.17.3 Order and consistency.
122 *
123 * The memory_order_* constants that denote the barrier behaviour of the
124 * atomic operations.
125 */
126
127 typedef enum {
128 memory_order_relaxed = __ATOMIC_RELAXED,
129 memory_order_consume = __ATOMIC_CONSUME,
130 memory_order_acquire = __ATOMIC_ACQUIRE,
131 memory_order_release = __ATOMIC_RELEASE,
132 memory_order_acq_rel = __ATOMIC_ACQ_REL,
133 memory_order_seq_cst = __ATOMIC_SEQ_CST
134 } memory_order;
135
136 /*
137 * 7.17.4 Fences.
138 */
139
140 static __inline void
141 atomic_thread_fence(memory_order __order __unused)
142 {
143
144 #ifdef __CLANG_ATOMICS
145 __c11_atomic_thread_fence(__order);
146 #elif defined(__GNUC_ATOMICS)
147 __atomic_thread_fence(__order);
148 #else
149 __sync_synchronize();
150 #endif
151 }
152
153 static __inline void
154 atomic_signal_fence(memory_order __order __unused)
155 {
156
157 #ifdef __CLANG_ATOMICS
158 __c11_atomic_signal_fence(__order);
159 #elif defined(__GNUC_ATOMICS)
160 __atomic_signal_fence(__order);
161 #else
162 __asm volatile ("" ::: "memory");
163 #endif
164 }
165
166 #if defined(__cplusplus) && !defined(_Bool)
167 #define _Bool bool
168 #define __bool_locally_defined
169 #endif
170
171 /*
172 * 7.17.5 Lock-free property.
173 */
174
175 #if defined(_KERNEL)
176 /* Atomics in kernelspace are always lock-free. */
177 #define atomic_is_lock_free(obj) \
178 ((void)(obj), (_Bool)1)
179 #elif defined(__CLANG_ATOMICS) || defined(__GNUC_ATOMICS)
180 #define atomic_is_lock_free(obj) \
181 __atomic_is_lock_free(sizeof(*(obj)), obj)
182 #else
183 #define atomic_is_lock_free(obj) \
184 ((void)(obj), sizeof((obj)->__val) <= sizeof(void *))
185 #endif
186
187 /*
188 * 7.17.6 Atomic integer types.
189 */
190
191 typedef _Atomic(_Bool) atomic_bool;
192 typedef _Atomic(char) atomic_char;
193 typedef _Atomic(signed char) atomic_schar;
194 typedef _Atomic(unsigned char) atomic_uchar;
195 typedef _Atomic(short) atomic_short;
196 typedef _Atomic(unsigned short) atomic_ushort;
197 typedef _Atomic(int) atomic_int;
198 typedef _Atomic(unsigned int) atomic_uint;
199 typedef _Atomic(long) atomic_long;
200 typedef _Atomic(unsigned long) atomic_ulong;
201 typedef _Atomic(long long) atomic_llong;
202 typedef _Atomic(unsigned long long) atomic_ullong;
203 typedef _Atomic(__char16_t) atomic_char16_t;
204 typedef _Atomic(__char32_t) atomic_char32_t;
205 typedef _Atomic(___wchar_t) atomic_wchar_t;
206 typedef _Atomic(__int_least8_t) atomic_int_least8_t;
207 typedef _Atomic(__uint_least8_t) atomic_uint_least8_t;
208 typedef _Atomic(__int_least16_t) atomic_int_least16_t;
209 typedef _Atomic(__uint_least16_t) atomic_uint_least16_t;
210 typedef _Atomic(__int_least32_t) atomic_int_least32_t;
211 typedef _Atomic(__uint_least32_t) atomic_uint_least32_t;
212 typedef _Atomic(__int_least64_t) atomic_int_least64_t;
213 typedef _Atomic(__uint_least64_t) atomic_uint_least64_t;
214 typedef _Atomic(__int_fast8_t) atomic_int_fast8_t;
215 typedef _Atomic(__uint_fast8_t) atomic_uint_fast8_t;
216 typedef _Atomic(__int_fast16_t) atomic_int_fast16_t;
217 typedef _Atomic(__uint_fast16_t) atomic_uint_fast16_t;
218 typedef _Atomic(__int_fast32_t) atomic_int_fast32_t;
219 typedef _Atomic(__uint_fast32_t) atomic_uint_fast32_t;
220 typedef _Atomic(__int_fast64_t) atomic_int_fast64_t;
221 typedef _Atomic(__uint_fast64_t) atomic_uint_fast64_t;
222 typedef _Atomic(__intptr_t) atomic_intptr_t;
223 typedef _Atomic(__uintptr_t) atomic_uintptr_t;
224 typedef _Atomic(__size_t) atomic_size_t;
225 typedef _Atomic(__ptrdiff_t) atomic_ptrdiff_t;
226 typedef _Atomic(__intmax_t) atomic_intmax_t;
227 typedef _Atomic(__uintmax_t) atomic_uintmax_t;
228
229 /*
230 * 7.17.7 Operations on atomic types.
231 */
232
233 /*
234 * Compiler-specific operations.
235 */
236
237 #if defined(__CLANG_ATOMICS)
238 #define atomic_compare_exchange_strong_explicit(object, expected, \
239 desired, success, failure) \
240 __c11_atomic_compare_exchange_strong(object, expected, desired, \
241 success, failure)
242 #define atomic_compare_exchange_weak_explicit(object, expected, \
243 desired, success, failure) \
244 __c11_atomic_compare_exchange_weak(object, expected, desired, \
245 success, failure)
246 #define atomic_exchange_explicit(object, desired, order) \
247 __c11_atomic_exchange(object, desired, order)
248 #define atomic_fetch_add_explicit(object, operand, order) \
249 __c11_atomic_fetch_add(object, operand, order)
250 #define atomic_fetch_and_explicit(object, operand, order) \
251 __c11_atomic_fetch_and(object, operand, order)
252 #define atomic_fetch_or_explicit(object, operand, order) \
253 __c11_atomic_fetch_or(object, operand, order)
254 #define atomic_fetch_sub_explicit(object, operand, order) \
255 __c11_atomic_fetch_sub(object, operand, order)
256 #define atomic_fetch_xor_explicit(object, operand, order) \
257 __c11_atomic_fetch_xor(object, operand, order)
258 #define atomic_load_explicit(object, order) \
259 __c11_atomic_load(object, order)
260 #define atomic_store_explicit(object, desired, order) \
261 __c11_atomic_store(object, desired, order)
262 #elif defined(__GNUC_ATOMICS)
263 #define atomic_compare_exchange_strong_explicit(object, expected, \
264 desired, success, failure) \
265 __atomic_compare_exchange_n(object, expected, \
266 desired, 0, success, failure)
267 #define atomic_compare_exchange_weak_explicit(object, expected, \
268 desired, success, failure) \
269 __atomic_compare_exchange_n(object, expected, \
270 desired, 1, success, failure)
271 #define atomic_exchange_explicit(object, desired, order) \
272 __atomic_exchange_n(object, desired, order)
273 #define atomic_fetch_add_explicit(object, operand, order) \
274 __atomic_fetch_add(object, operand, order)
275 #define atomic_fetch_and_explicit(object, operand, order) \
276 __atomic_fetch_and(object, operand, order)
277 #define atomic_fetch_or_explicit(object, operand, order) \
278 __atomic_fetch_or(object, operand, order)
279 #define atomic_fetch_sub_explicit(object, operand, order) \
280 __atomic_fetch_sub(object, operand, order)
281 #define atomic_fetch_xor_explicit(object, operand, order) \
282 __atomic_fetch_xor(object, operand, order)
283 #define atomic_load_explicit(object, order) \
284 __atomic_load_n(object, order)
285 #define atomic_store_explicit(object, desired, order) \
286 __atomic_store_n(object, desired, order)
287 #else
288 #define __atomic_apply_stride(object, operand) \
289 (((__typeof__((object)->__val))0) + (operand))
290 #define atomic_compare_exchange_strong_explicit(object, expected, \
291 desired, success, failure) __extension__ ({ \
292 __typeof__(expected) __ep = (expected); \
293 __typeof__(*__ep) __e = *__ep; \
294 (void)(success); (void)(failure); \
295 (_Bool)((*__ep = __sync_val_compare_and_swap(&(object)->__val, \
296 __e, desired)) == __e); \
297 })
298 #define atomic_compare_exchange_weak_explicit(object, expected, \
299 desired, success, failure) \
300 atomic_compare_exchange_strong_explicit(object, expected, \
301 desired, success, failure)
302 #if __has_builtin(__sync_swap)
303 /* Clang provides a full-barrier atomic exchange - use it if available. */
304 #define atomic_exchange_explicit(object, desired, order) \
305 ((void)(order), __sync_swap(&(object)->__val, desired))
306 #else
307 /*
308 * __sync_lock_test_and_set() is only an acquire barrier in theory (although in
309 * practice it is usually a full barrier) so we need an explicit barrier before
310 * it.
311 */
312 #define atomic_exchange_explicit(object, desired, order) \
313 __extension__ ({ \
314 __typeof__(object) __o = (object); \
315 __typeof__(desired) __d = (desired); \
316 (void)(order); \
317 __sync_synchronize(); \
318 __sync_lock_test_and_set(&(__o)->__val, __d); \
319 })
320 #endif
321 #define atomic_fetch_add_explicit(object, operand, order) \
322 ((void)(order), __sync_fetch_and_add(&(object)->__val, \
323 __atomic_apply_stride(object, operand)))
324 #define atomic_fetch_and_explicit(object, operand, order) \
325 ((void)(order), __sync_fetch_and_and(&(object)->__val, operand))
326 #define atomic_fetch_or_explicit(object, operand, order) \
327 ((void)(order), __sync_fetch_and_or(&(object)->__val, operand))
328 #define atomic_fetch_sub_explicit(object, operand, order) \
329 ((void)(order), __sync_fetch_and_sub(&(object)->__val, \
330 __atomic_apply_stride(object, operand)))
331 #define atomic_fetch_xor_explicit(object, operand, order) \
332 ((void)(order), __sync_fetch_and_xor(&(object)->__val, operand))
333 #define atomic_load_explicit(object, order) \
334 ((void)(order), __sync_fetch_and_add(&(object)->__val, 0))
335 #define atomic_store_explicit(object, desired, order) \
336 ((void)atomic_exchange_explicit(object, desired, order))
337 #endif
338
339 /*
340 * Convenience functions.
341 *
342 * Don't provide these in kernel space. In kernel space, we should be
343 * disciplined enough to always provide explicit barriers.
344 */
345
346 #ifndef _KERNEL
347 #define atomic_compare_exchange_strong(object, expected, desired) \
348 atomic_compare_exchange_strong_explicit(object, expected, \
349 desired, memory_order_seq_cst, memory_order_seq_cst)
350 #define atomic_compare_exchange_weak(object, expected, desired) \
351 atomic_compare_exchange_weak_explicit(object, expected, \
352 desired, memory_order_seq_cst, memory_order_seq_cst)
353 #define atomic_exchange(object, desired) \
354 atomic_exchange_explicit(object, desired, memory_order_seq_cst)
355 #define atomic_fetch_add(object, operand) \
356 atomic_fetch_add_explicit(object, operand, memory_order_seq_cst)
357 #define atomic_fetch_and(object, operand) \
358 atomic_fetch_and_explicit(object, operand, memory_order_seq_cst)
359 #define atomic_fetch_or(object, operand) \
360 atomic_fetch_or_explicit(object, operand, memory_order_seq_cst)
361 #define atomic_fetch_sub(object, operand) \
362 atomic_fetch_sub_explicit(object, operand, memory_order_seq_cst)
363 #define atomic_fetch_xor(object, operand) \
364 atomic_fetch_xor_explicit(object, operand, memory_order_seq_cst)
365 #define atomic_load(object) \
366 atomic_load_explicit(object, memory_order_seq_cst)
367 #define atomic_store(object, desired) \
368 atomic_store_explicit(object, desired, memory_order_seq_cst)
369 #endif /* !_KERNEL */
370
371 /*
372 * 7.17.8 Atomic flag type and operations.
373 *
374 * XXX: Assume atomic_bool can be used as an atomic_flag. Is there some
375 * kind of compiler built-in type we could use?
376 */
377
378 typedef struct {
379 atomic_bool __flag;
380 } atomic_flag;
381 #define ATOMIC_FLAG_INIT { ATOMIC_VAR_INIT(0) }
382
383 static __inline _Bool
384 atomic_flag_test_and_set_explicit(volatile atomic_flag *__object,
385 memory_order __order)
386 {
387 return (atomic_exchange_explicit(&__object->__flag, 1, __order));
388 }
389
390 static __inline void
391 atomic_flag_clear_explicit(volatile atomic_flag *__object, memory_order __order)
392 {
393
394 atomic_store_explicit(&__object->__flag, 0, __order);
395 }
396
397 #ifndef _KERNEL
398 static __inline _Bool
399 atomic_flag_test_and_set(volatile atomic_flag *__object)
400 {
401
402 return (atomic_flag_test_and_set_explicit(__object,
403 memory_order_seq_cst));
404 }
405
406 static __inline void
407 atomic_flag_clear(volatile atomic_flag *__object)
408 {
409
410 atomic_flag_clear_explicit(__object, memory_order_seq_cst);
411 }
412 #endif /* !_KERNEL */
413
414 #ifdef __bool_locally_defined
415 #undef _Bool
416 #undef __bool_locally_defined
417 #endif
418
419 #endif /* !_STDATOMIC_H_ */
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