Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/sys/stdatomic.h
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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 /* 167 * 7.17.5 Lock-free property. 168 */ 169 170 #if defined(_KERNEL) 171 /* Atomics in kernelspace are always lock-free. */ 172 #define atomic_is_lock_free(obj) \ 173 ((void)(obj), (_Bool)1) 174 #elif defined(__CLANG_ATOMICS) || defined(__GNUC_ATOMICS) 175 #define atomic_is_lock_free(obj) \ 176 __atomic_is_lock_free(sizeof(*(obj)), obj) 177 #else 178 #define atomic_is_lock_free(obj) \ 179 ((void)(obj), sizeof((obj)->__val) <= sizeof(void *)) 180 #endif 181 182 /* 183 * 7.17.6 Atomic integer types. 184 */ 185 186 typedef _Atomic(_Bool) atomic_bool; 187 typedef _Atomic(char) atomic_char; 188 typedef _Atomic(signed char) atomic_schar; 189 typedef _Atomic(unsigned char) atomic_uchar; 190 typedef _Atomic(short) atomic_short; 191 typedef _Atomic(unsigned short) atomic_ushort; 192 typedef _Atomic(int) atomic_int; 193 typedef _Atomic(unsigned int) atomic_uint; 194 typedef _Atomic(long) atomic_long; 195 typedef _Atomic(unsigned long) atomic_ulong; 196 typedef _Atomic(long long) atomic_llong; 197 typedef _Atomic(unsigned long long) atomic_ullong; 198 typedef _Atomic(__char16_t) atomic_char16_t; 199 typedef _Atomic(__char32_t) atomic_char32_t; 200 typedef _Atomic(___wchar_t) atomic_wchar_t; 201 typedef _Atomic(__int_least8_t) atomic_int_least8_t; 202 typedef _Atomic(__uint_least8_t) atomic_uint_least8_t; 203 typedef _Atomic(__int_least16_t) atomic_int_least16_t; 204 typedef _Atomic(__uint_least16_t) atomic_uint_least16_t; 205 typedef _Atomic(__int_least32_t) atomic_int_least32_t; 206 typedef _Atomic(__uint_least32_t) atomic_uint_least32_t; 207 typedef _Atomic(__int_least64_t) atomic_int_least64_t; 208 typedef _Atomic(__uint_least64_t) atomic_uint_least64_t; 209 typedef _Atomic(__int_fast8_t) atomic_int_fast8_t; 210 typedef _Atomic(__uint_fast8_t) atomic_uint_fast8_t; 211 typedef _Atomic(__int_fast16_t) atomic_int_fast16_t; 212 typedef _Atomic(__uint_fast16_t) atomic_uint_fast16_t; 213 typedef _Atomic(__int_fast32_t) atomic_int_fast32_t; 214 typedef _Atomic(__uint_fast32_t) atomic_uint_fast32_t; 215 typedef _Atomic(__int_fast64_t) atomic_int_fast64_t; 216 typedef _Atomic(__uint_fast64_t) atomic_uint_fast64_t; 217 typedef _Atomic(__intptr_t) atomic_intptr_t; 218 typedef _Atomic(__uintptr_t) atomic_uintptr_t; 219 typedef _Atomic(__size_t) atomic_size_t; 220 typedef _Atomic(__ptrdiff_t) atomic_ptrdiff_t; 221 typedef _Atomic(__intmax_t) atomic_intmax_t; 222 typedef _Atomic(__uintmax_t) atomic_uintmax_t; 223 224 /* 225 * 7.17.7 Operations on atomic types. 226 */ 227 228 /* 229 * Compiler-specific operations. 230 */ 231 232 #if defined(__CLANG_ATOMICS) 233 #define atomic_compare_exchange_strong_explicit(object, expected, \ 234 desired, success, failure) \ 235 __c11_atomic_compare_exchange_strong(object, expected, desired, \ 236 success, failure) 237 #define atomic_compare_exchange_weak_explicit(object, expected, \ 238 desired, success, failure) \ 239 __c11_atomic_compare_exchange_weak(object, expected, desired, \ 240 success, failure) 241 #define atomic_exchange_explicit(object, desired, order) \ 242 __c11_atomic_exchange(object, desired, order) 243 #define atomic_fetch_add_explicit(object, operand, order) \ 244 __c11_atomic_fetch_add(object, operand, order) 245 #define atomic_fetch_and_explicit(object, operand, order) \ 246 __c11_atomic_fetch_and(object, operand, order) 247 #define atomic_fetch_or_explicit(object, operand, order) \ 248 __c11_atomic_fetch_or(object, operand, order) 249 #define atomic_fetch_sub_explicit(object, operand, order) \ 250 __c11_atomic_fetch_sub(object, operand, order) 251 #define atomic_fetch_xor_explicit(object, operand, order) \ 252 __c11_atomic_fetch_xor(object, operand, order) 253 #define atomic_load_explicit(object, order) \ 254 __c11_atomic_load(object, order) 255 #define atomic_store_explicit(object, desired, order) \ 256 __c11_atomic_store(object, desired, order) 257 #elif defined(__GNUC_ATOMICS) 258 #define atomic_compare_exchange_strong_explicit(object, expected, \ 259 desired, success, failure) \ 260 __atomic_compare_exchange_n(object, expected, \ 261 desired, 0, success, failure) 262 #define atomic_compare_exchange_weak_explicit(object, expected, \ 263 desired, success, failure) \ 264 __atomic_compare_exchange_n(object, expected, \ 265 desired, 1, success, failure) 266 #define atomic_exchange_explicit(object, desired, order) \ 267 __atomic_exchange_n(object, desired, order) 268 #define atomic_fetch_add_explicit(object, operand, order) \ 269 __atomic_fetch_add(object, operand, order) 270 #define atomic_fetch_and_explicit(object, operand, order) \ 271 __atomic_fetch_and(object, operand, order) 272 #define atomic_fetch_or_explicit(object, operand, order) \ 273 __atomic_fetch_or(object, operand, order) 274 #define atomic_fetch_sub_explicit(object, operand, order) \ 275 __atomic_fetch_sub(object, operand, order) 276 #define atomic_fetch_xor_explicit(object, operand, order) \ 277 __atomic_fetch_xor(object, operand, order) 278 #define atomic_load_explicit(object, order) \ 279 __atomic_load_n(object, order) 280 #define atomic_store_explicit(object, desired, order) \ 281 __atomic_store_n(object, desired, order) 282 #else 283 #define __atomic_apply_stride(object, operand) \ 284 (((__typeof__((object)->__val))0) + (operand)) 285 #define atomic_compare_exchange_strong_explicit(object, expected, \ 286 desired, success, failure) __extension__ ({ \ 287 __typeof__(expected) __ep = (expected); \ 288 __typeof__(*__ep) __e = *__ep; \ 289 (void)(success); (void)(failure); \ 290 (_Bool)((*__ep = __sync_val_compare_and_swap(&(object)->__val, \ 291 __e, desired)) == __e); \ 292 }) 293 #define atomic_compare_exchange_weak_explicit(object, expected, \ 294 desired, success, failure) \ 295 atomic_compare_exchange_strong_explicit(object, expected, \ 296 desired, success, failure) 297 #if __has_builtin(__sync_swap) 298 /* Clang provides a full-barrier atomic exchange - use it if available. */ 299 #define atomic_exchange_explicit(object, desired, order) \ 300 ((void)(order), __sync_swap(&(object)->__val, desired)) 301 #else 302 /* 303 * __sync_lock_test_and_set() is only an acquire barrier in theory (although in 304 * practice it is usually a full barrier) so we need an explicit barrier before 305 * it. 306 */ 307 #define atomic_exchange_explicit(object, desired, order) \ 308 __extension__ ({ \ 309 __typeof__(object) __o = (object); \ 310 __typeof__(desired) __d = (desired); \ 311 (void)(order); \ 312 __sync_synchronize(); \ 313 __sync_lock_test_and_set(&(__o)->__val, __d); \ 314 }) 315 #endif 316 #define atomic_fetch_add_explicit(object, operand, order) \ 317 ((void)(order), __sync_fetch_and_add(&(object)->__val, \ 318 __atomic_apply_stride(object, operand))) 319 #define atomic_fetch_and_explicit(object, operand, order) \ 320 ((void)(order), __sync_fetch_and_and(&(object)->__val, operand)) 321 #define atomic_fetch_or_explicit(object, operand, order) \ 322 ((void)(order), __sync_fetch_and_or(&(object)->__val, operand)) 323 #define atomic_fetch_sub_explicit(object, operand, order) \ 324 ((void)(order), __sync_fetch_and_sub(&(object)->__val, \ 325 __atomic_apply_stride(object, operand))) 326 #define atomic_fetch_xor_explicit(object, operand, order) \ 327 ((void)(order), __sync_fetch_and_xor(&(object)->__val, operand)) 328 #define atomic_load_explicit(object, order) \ 329 ((void)(order), __sync_fetch_and_add(&(object)->__val, 0)) 330 #define atomic_store_explicit(object, desired, order) \ 331 ((void)atomic_exchange_explicit(object, desired, order)) 332 #endif 333 334 /* 335 * Convenience functions. 336 * 337 * Don't provide these in kernel space. In kernel space, we should be 338 * disciplined enough to always provide explicit barriers. 339 */ 340 341 #ifndef _KERNEL 342 #define atomic_compare_exchange_strong(object, expected, desired) \ 343 atomic_compare_exchange_strong_explicit(object, expected, \ 344 desired, memory_order_seq_cst, memory_order_seq_cst) 345 #define atomic_compare_exchange_weak(object, expected, desired) \ 346 atomic_compare_exchange_weak_explicit(object, expected, \ 347 desired, memory_order_seq_cst, memory_order_seq_cst) 348 #define atomic_exchange(object, desired) \ 349 atomic_exchange_explicit(object, desired, memory_order_seq_cst) 350 #define atomic_fetch_add(object, operand) \ 351 atomic_fetch_add_explicit(object, operand, memory_order_seq_cst) 352 #define atomic_fetch_and(object, operand) \ 353 atomic_fetch_and_explicit(object, operand, memory_order_seq_cst) 354 #define atomic_fetch_or(object, operand) \ 355 atomic_fetch_or_explicit(object, operand, memory_order_seq_cst) 356 #define atomic_fetch_sub(object, operand) \ 357 atomic_fetch_sub_explicit(object, operand, memory_order_seq_cst) 358 #define atomic_fetch_xor(object, operand) \ 359 atomic_fetch_xor_explicit(object, operand, memory_order_seq_cst) 360 #define atomic_load(object) \ 361 atomic_load_explicit(object, memory_order_seq_cst) 362 #define atomic_store(object, desired) \ 363 atomic_store_explicit(object, desired, memory_order_seq_cst) 364 #endif /* !_KERNEL */ 365 366 /* 367 * 7.17.8 Atomic flag type and operations. 368 * 369 * XXX: Assume atomic_bool can be used as an atomic_flag. Is there some 370 * kind of compiler built-in type we could use? 371 */ 372 373 typedef struct { 374 atomic_bool __flag; 375 } atomic_flag; 376 377 #define ATOMIC_FLAG_INIT { ATOMIC_VAR_INIT(0) } 378 379 static __inline _Bool 380 atomic_flag_test_and_set_explicit(volatile atomic_flag *__object, 381 memory_order __order) 382 { 383 return (atomic_exchange_explicit(&__object->__flag, 1, __order)); 384 } 385 386 static __inline void 387 atomic_flag_clear_explicit(volatile atomic_flag *__object, memory_order __order) 388 { 389 390 atomic_store_explicit(&__object->__flag, 0, __order); 391 } 392 393 #ifndef _KERNEL 394 static __inline _Bool 395 atomic_flag_test_and_set(volatile atomic_flag *__object) 396 { 397 398 return (atomic_flag_test_and_set_explicit(__object, 399 memory_order_seq_cst)); 400 } 401 402 static __inline void 403 atomic_flag_clear(volatile atomic_flag *__object) 404 { 405 406 atomic_flag_clear_explicit(__object, memory_order_seq_cst); 407 } 408 #endif /* !_KERNEL */ 409 410 #endif /* !_STDATOMIC_H_ */
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