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