1 /*-
2 * Copyright (c) 2011 Ed Schouten <ed@FreeBSD.org>
3 * David Chisnall <theraven@FreeBSD.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 * $FreeBSD$
28 */
30 #ifndef _STDATOMIC_H_
31 #define _STDATOMIC_H_
33 #include <sys/cdefs.h>
34 #include <sys/types.h>
35 #include <stdbool.h>
37 #if __has_extension(c_atomic) || __has_extension(cxx_atomic)
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
47 /*
48 * 7.17.1 Atomic lock-free macros.
49 */
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
82 /*
83 * 7.17.2 Initialization.
84 */
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
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 */
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
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 */
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;
135 /*
136 * 7.17.4 Fences.
137 */
139 static __inline void
140 atomic_thread_fence(memory_order __order __unused)
141 {
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 }
152 static __inline void
153 atomic_signal_fence(memory_order __order __unused)
154 {
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 }
165 /*
166 * 7.17.5 Lock-free property.
167 */
169 #if defined(_KERNEL)
170 /* Atomics in kernelspace are always lock-free. */
171 #define atomic_is_lock_free(obj) \
172 ((void)(obj), (_Bool)1)
173 #elif defined(__CLANG_ATOMICS)
174 #define atomic_is_lock_free(obj) \
175 __atomic_is_lock_free(sizeof(*(obj)), obj)
176 #elif defined(__GNUC_ATOMICS)
177 #define atomic_is_lock_free(obj) \
178 __atomic_is_lock_free(sizeof((obj)->__val), &(obj)->__val)
179 #else
180 #define atomic_is_lock_free(obj) \
181 ((void)(obj), sizeof((obj)->__val) <= sizeof(void *))
182 #endif
184 /*
185 * 7.17.6 Atomic integer types.
186 */
188 #if !__has_extension(c_atomic) && !__has_extension(cxx_atomic)
189 /*
190 * No native support for _Atomic(). Place object in structure to prevent
191 * most forms of direct non-atomic access.
192 */
193 #define _Atomic(T) struct { T volatile __val; }
194 #endif
196 typedef _Atomic(bool) atomic_bool;
197 typedef _Atomic(char) atomic_char;
198 typedef _Atomic(signed char) atomic_schar;
199 typedef _Atomic(unsigned char) atomic_uchar;
200 typedef _Atomic(short) atomic_short;
201 typedef _Atomic(unsigned short) atomic_ushort;
202 typedef _Atomic(int) atomic_int;
203 typedef _Atomic(unsigned int) atomic_uint;
204 typedef _Atomic(long) atomic_long;
205 typedef _Atomic(unsigned long) atomic_ulong;
206 typedef _Atomic(long long) atomic_llong;
207 typedef _Atomic(unsigned long long) atomic_ullong;
208 typedef _Atomic(char16_t) atomic_char16_t;
209 typedef _Atomic(char32_t) atomic_char32_t;
210 typedef _Atomic(wchar_t) atomic_wchar_t;
211 typedef _Atomic(int_least8_t) atomic_int_least8_t;
212 typedef _Atomic(uint_least8_t) atomic_uint_least8_t;
213 typedef _Atomic(int_least16_t) atomic_int_least16_t;
214 typedef _Atomic(uint_least16_t) atomic_uint_least16_t;
215 typedef _Atomic(int_least32_t) atomic_int_least32_t;
216 typedef _Atomic(uint_least32_t) atomic_uint_least32_t;
217 typedef _Atomic(int_least64_t) atomic_int_least64_t;
218 typedef _Atomic(uint_least64_t) atomic_uint_least64_t;
219 typedef _Atomic(int_fast8_t) atomic_int_fast8_t;
220 typedef _Atomic(uint_fast8_t) atomic_uint_fast8_t;
221 typedef _Atomic(int_fast16_t) atomic_int_fast16_t;
222 typedef _Atomic(uint_fast16_t) atomic_uint_fast16_t;
223 typedef _Atomic(int_fast32_t) atomic_int_fast32_t;
224 typedef _Atomic(uint_fast32_t) atomic_uint_fast32_t;
225 typedef _Atomic(int_fast64_t) atomic_int_fast64_t;
226 typedef _Atomic(uint_fast64_t) atomic_uint_fast64_t;
227 typedef _Atomic(intptr_t) atomic_intptr_t;
228 typedef _Atomic(uintptr_t) atomic_uintptr_t;
229 typedef _Atomic(size_t) atomic_size_t;
230 typedef _Atomic(ptrdiff_t) atomic_ptrdiff_t;
231 typedef _Atomic(intmax_t) atomic_intmax_t;
232 typedef _Atomic(uintmax_t) atomic_uintmax_t;
234 /*
235 * 7.17.7 Operations on atomic types.
236 */
238 /*
239 * Compiler-specific operations.
240 */
242 #if defined(__CLANG_ATOMICS)
243 #define atomic_compare_exchange_strong_explicit(object, expected, \
244 desired, success, failure) \
245 __c11_atomic_compare_exchange_strong(object, expected, desired, \
246 success, failure)
247 #define atomic_compare_exchange_weak_explicit(object, expected, \
248 desired, success, failure) \
249 __c11_atomic_compare_exchange_weak(object, expected, desired, \
250 success, failure)
251 #define atomic_exchange_explicit(object, desired, order) \
252 __c11_atomic_exchange(object, desired, order)
253 #define atomic_fetch_add_explicit(object, operand, order) \
254 __c11_atomic_fetch_add(object, operand, order)
255 #define atomic_fetch_and_explicit(object, operand, order) \
256 __c11_atomic_fetch_and(object, operand, order)
257 #define atomic_fetch_or_explicit(object, operand, order) \
258 __c11_atomic_fetch_or(object, operand, order)
259 #define atomic_fetch_sub_explicit(object, operand, order) \
260 __c11_atomic_fetch_sub(object, operand, order)
261 #define atomic_fetch_xor_explicit(object, operand, order) \
262 __c11_atomic_fetch_xor(object, operand, order)
263 #define atomic_load_explicit(object, order) \
264 __c11_atomic_load(object, order)
265 #define atomic_store_explicit(object, desired, order) \
266 __c11_atomic_store(object, desired, order)
267 #elif defined(__GNUC_ATOMICS)
268 #define atomic_compare_exchange_strong_explicit(object, expected, \
269 desired, success, failure) \
270 __atomic_compare_exchange_n(&(object)->__val, expected, \
271 desired, 0, success, failure)
272 #define atomic_compare_exchange_weak_explicit(object, expected, \
273 desired, success, failure) \
274 __atomic_compare_exchange_n(&(object)->__val, expected, \
275 desired, 1, success, failure)
276 #define atomic_exchange_explicit(object, desired, order) \
277 __atomic_exchange_n(&(object)->__val, desired, order)
278 #define atomic_fetch_add_explicit(object, operand, order) \
279 __atomic_fetch_add(&(object)->__val, operand, order)
280 #define atomic_fetch_and_explicit(object, operand, order) \
281 __atomic_fetch_and(&(object)->__val, operand, order)
282 #define atomic_fetch_or_explicit(object, operand, order) \
283 __atomic_fetch_or(&(object)->__val, operand, order)
284 #define atomic_fetch_sub_explicit(object, operand, order) \
285 __atomic_fetch_sub(&(object)->__val, operand, order)
286 #define atomic_fetch_xor_explicit(object, operand, order) \
287 __atomic_fetch_xor(&(object)->__val, operand, order)
288 #define atomic_load_explicit(object, order) \
289 __atomic_load_n(&(object)->__val, order)
290 #define atomic_store_explicit(object, desired, order) \
291 __atomic_store_n(&(object)->__val, desired, order)
292 #else
293 #define __atomic_apply_stride(object, operand) \
294 (((__typeof__((object)->__val))0) + (operand))
295 #define atomic_compare_exchange_strong_explicit(object, expected, \
296 desired, success, failure) __extension__ ({ \
297 __typeof__(expected) __ep = (expected); \
298 __typeof__(*__ep) __e = *__ep; \
299 (void)(success); (void)(failure); \
300 (bool)((*__ep = __sync_val_compare_and_swap(&(object)->__val, \
301 __e, desired)) == __e); \
302 })
303 #define atomic_compare_exchange_weak_explicit(object, expected, \
304 desired, success, failure) \
305 atomic_compare_exchange_strong_explicit(object, expected, \
306 desired, success, failure)
307 #if __has_builtin(__sync_swap)
308 /* Clang provides a full-barrier atomic exchange - use it if available. */
309 #define atomic_exchange_explicit(object, desired, order) \
310 ((void)(order), __sync_swap(&(object)->__val, desired))
311 #else
312 /*
313 * __sync_lock_test_and_set() is only an acquire barrier in theory (although in
314 * practice it is usually a full barrier) so we need an explicit barrier before
315 * it.
316 */
317 #define atomic_exchange_explicit(object, desired, order) \
318 __extension__ ({ \
319 __typeof__(object) __o = (object); \
320 __typeof__(desired) __d = (desired); \
321 (void)(order); \
322 __sync_synchronize(); \
323 __sync_lock_test_and_set(&(__o)->__val, __d); \
324 })
325 #endif
326 #define atomic_fetch_add_explicit(object, operand, order) \
327 ((void)(order), __sync_fetch_and_add(&(object)->__val, \
328 __atomic_apply_stride(object, operand)))
329 #define atomic_fetch_and_explicit(object, operand, order) \
330 ((void)(order), __sync_fetch_and_and(&(object)->__val, operand))
331 #define atomic_fetch_or_explicit(object, operand, order) \
332 ((void)(order), __sync_fetch_and_or(&(object)->__val, operand))
333 #define atomic_fetch_sub_explicit(object, operand, order) \
334 ((void)(order), __sync_fetch_and_sub(&(object)->__val, \
335 __atomic_apply_stride(object, operand)))
336 #define atomic_fetch_xor_explicit(object, operand, order) \
337 ((void)(order), __sync_fetch_and_xor(&(object)->__val, operand))
338 #define atomic_load_explicit(object, order) \
339 ((void)(order), __sync_fetch_and_add(&(object)->__val, 0))
340 #define atomic_store_explicit(object, desired, order) \
341 ((void)atomic_exchange_explicit(object, desired, order))
342 #endif
344 /*
345 * Convenience functions.
346 *
347 * Don't provide these in kernel space. In kernel space, we should be
348 * disciplined enough to always provide explicit barriers.
349 */
351 #ifndef _KERNEL
352 #define atomic_compare_exchange_strong(object, expected, desired) \
353 atomic_compare_exchange_strong_explicit(object, expected, \
354 desired, memory_order_seq_cst, memory_order_seq_cst)
355 #define atomic_compare_exchange_weak(object, expected, desired) \
356 atomic_compare_exchange_weak_explicit(object, expected, \
357 desired, memory_order_seq_cst, memory_order_seq_cst)
358 #define atomic_exchange(object, desired) \
359 atomic_exchange_explicit(object, desired, memory_order_seq_cst)
360 #define atomic_fetch_add(object, operand) \
361 atomic_fetch_add_explicit(object, operand, memory_order_seq_cst)
362 #define atomic_fetch_and(object, operand) \
363 atomic_fetch_and_explicit(object, operand, memory_order_seq_cst)
364 #define atomic_fetch_or(object, operand) \
365 atomic_fetch_or_explicit(object, operand, memory_order_seq_cst)
366 #define atomic_fetch_sub(object, operand) \
367 atomic_fetch_sub_explicit(object, operand, memory_order_seq_cst)
368 #define atomic_fetch_xor(object, operand) \
369 atomic_fetch_xor_explicit(object, operand, memory_order_seq_cst)
370 #define atomic_load(object) \
371 atomic_load_explicit(object, memory_order_seq_cst)
372 #define atomic_store(object, desired) \
373 atomic_store_explicit(object, desired, memory_order_seq_cst)
374 #endif /* !_KERNEL */
376 /*
377 * 7.17.8 Atomic flag type and operations.
378 *
379 * XXX: Assume atomic_bool can be used as an atomic_flag. Is there some
380 * kind of compiler built-in type we could use?
381 */
383 typedef struct {
384 atomic_bool __flag;
385 } atomic_flag;
387 #define ATOMIC_FLAG_INIT { ATOMIC_VAR_INIT(0) }
389 static __inline bool
390 atomic_flag_test_and_set_explicit(volatile atomic_flag *__object,
391 memory_order __order)
392 {
393 return (atomic_exchange_explicit(&__object->__flag, 1, __order));
394 }
396 static __inline void
397 atomic_flag_clear_explicit(volatile atomic_flag *__object, memory_order __order)
398 {
400 atomic_store_explicit(&__object->__flag, 0, __order);
401 }
403 #ifndef _KERNEL
404 static __inline bool
405 atomic_flag_test_and_set(volatile atomic_flag *__object)
406 {
408 return (atomic_flag_test_and_set_explicit(__object,
409 memory_order_seq_cst));
410 }
412 static __inline void
413 atomic_flag_clear(volatile atomic_flag *__object)
414 {
416 atomic_flag_clear_explicit(__object, memory_order_seq_cst);
417 }
418 #endif /* !_KERNEL */
420 #endif /* !_STDATOMIC_H_ */