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