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 /*
 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 #define ATOMIC_FLAG_INIT                { ATOMIC_VAR_INIT(0) }
 377
 378 static __inline _Bool
 379 atomic_flag_test_and_set_explicit(volatile atomic_flag *__object,
 380     memory_order __order)
 381 {
 382         return (atomic_exchange_explicit(&__object->__flag, 1, __order));
 383 }
 384
 385 static __inline void
 386 atomic_flag_clear_explicit(volatile atomic_flag *__object, memory_order __order)
 387 {
 388
 389         atomic_store_explicit(&__object->__flag, 0, __order);
 390 }
 391
 392 #ifndef _KERNEL
 393 static __inline _Bool
 394 atomic_flag_test_and_set(volatile atomic_flag *__object)
 395 {
 396
 397         return (atomic_flag_test_and_set_explicit(__object,
 398             memory_order_seq_cst));
 399 }
 400
 401 static __inline void
 402 atomic_flag_clear(volatile atomic_flag *__object)
 403 {
 404
 405         atomic_flag_clear_explicit(__object, memory_order_seq_cst);
 406 }
 407 #endif /* !_KERNEL */
 408
 409 #endif /* !_STDATOMIC_H_ */