1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __LINUX_COMPILER_ATTRIBUTES_H 3 #define __LINUX_COMPILER_ATTRIBUTES_H 4 5 /* 6 * The attributes in this file are unconditionally defined and they directly 7 * map to compiler attribute(s), unless one of the compilers does not support 8 * the attribute. In that case, __has_attribute is used to check for support 9 * and the reason is stated in its comment ("Optional: ..."). 10 * 11 * Any other "attributes" (i.e. those that depend on a configuration option, 12 * on a compiler, on an architecture, on plugins, on other attributes...) 13 * should be defined elsewhere (e.g. compiler_types.h or compiler-*.h). 14 * The intention is to keep this file as simple as possible, as well as 15 * compiler- and version-agnostic (e.g. avoiding GCC_VERSION checks). 16 * 17 * This file is meant to be sorted (by actual attribute name, 18 * not by #define identifier). Use the __attribute__((__name__)) syntax 19 * (i.e. with underscores) to avoid future collisions with other macros. 20 * Provide links to the documentation of each supported compiler, if it exists. 21 */ 22 23 /* 24 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alias-function-attribute 25 */ 26 #define __alias(symbol) __attribute__((__alias__(#symbol))) 27 28 /* 29 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-aligned-function-attribute 30 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-aligned-type-attribute 31 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-aligned-variable-attribute 32 */ 33 #define __aligned(x) __attribute__((__aligned__(x))) 34 #define __aligned_largest __attribute__((__aligned__)) 35 36 /* 37 * Note: do not use this directly. Instead, use __alloc_size() since it is conditionally 38 * available and includes other attributes. For GCC < 9.1, __alloc_size__ gets undefined 39 * in compiler-gcc.h, due to misbehaviors. 40 * 41 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alloc_005fsize-function-attribute 42 * clang: https://clang.llvm.org/docs/AttributeReference.html#alloc-size 43 */ 44 #define __alloc_size__(x, ...) __attribute__((__alloc_size__(x, ## __VA_ARGS__))) 45 46 /* 47 * Note: users of __always_inline currently do not write "inline" themselves, 48 * which seems to be required by gcc to apply the attribute according 49 * to its docs (and also "warning: always_inline function might not be 50 * inlinable [-Wattributes]" is emitted). 51 * 52 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-always_005finline-function-attribute 53 * clang: mentioned 54 */ 55 #define __always_inline inline __attribute__((__always_inline__)) 56 57 /* 58 * The second argument is optional (default 0), so we use a variadic macro 59 * to make the shorthand. 60 * 61 * Beware: Do not apply this to functions which may return 62 * ERR_PTRs. Also, it is probably unwise to apply it to functions 63 * returning extra information in the low bits (but in that case the 64 * compiler should see some alignment anyway, when the return value is 65 * massaged by 'flags = ptr & 3; ptr &= ~3;'). 66 * 67 * Optional: not supported by icc 68 * 69 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute 70 * clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned 71 */ 72 #if __has_attribute(__assume_aligned__) 73 # define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) 74 #else 75 # define __assume_aligned(a, ...) 76 #endif 77 78 /* 79 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-cleanup-variable-attribute 80 * clang: https://clang.llvm.org/docs/AttributeReference.html#cleanup 81 */ 82 #define __cleanup(func) __attribute__((__cleanup__(func))) 83 84 /* 85 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-cold-function-attribute 86 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-cold-label-attribute 87 */ 88 #define __cold __attribute__((__cold__)) 89 90 /* 91 * Note the long name. 92 * 93 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute 94 */ 95 #define __attribute_const__ __attribute__((__const__)) 96 97 /* 98 * Optional: only supported since gcc >= 9 99 * Optional: not supported by clang 100 * Optional: not supported by icc 101 * 102 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute 103 */ 104 #if __has_attribute(__copy__) 105 # define __copy(symbol) __attribute__((__copy__(symbol))) 106 #else 107 # define __copy(symbol) 108 #endif 109 110 /* 111 * Optional: not supported by gcc 112 * Optional: only supported since clang >= 14.0 113 * Optional: not supported by icc 114 * 115 * clang: https://clang.llvm.org/docs/AttributeReference.html#diagnose_as_builtin 116 */ 117 #if __has_attribute(__diagnose_as_builtin__) 118 # define __diagnose_as(builtin...) __attribute__((__diagnose_as_builtin__(builtin))) 119 #else 120 # define __diagnose_as(builtin...) 121 #endif 122 123 /* 124 * Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated' 125 * attribute warnings entirely and for good") for more information. 126 * 127 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute 128 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute 129 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute 130 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute 131 * clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated 132 */ 133 #define __deprecated 134 135 /* 136 * Optional: not supported by clang 137 * Optional: not supported by icc 138 * 139 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute 140 */ 141 #if __has_attribute(__designated_init__) 142 # define __designated_init __attribute__((__designated_init__)) 143 #else 144 # define __designated_init 145 #endif 146 147 /* 148 * Optional: only supported since clang >= 14.0 149 * 150 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-error-function-attribute 151 */ 152 #if __has_attribute(__error__) 153 # define __compiletime_error(msg) __attribute__((__error__(msg))) 154 #else 155 # define __compiletime_error(msg) 156 #endif 157 158 /* 159 * Optional: not supported by clang 160 * 161 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute 162 */ 163 #if __has_attribute(__externally_visible__) 164 # define __visible __attribute__((__externally_visible__)) 165 #else 166 # define __visible 167 #endif 168 169 /* 170 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute 171 * clang: https://clang.llvm.org/docs/AttributeReference.html#format 172 */ 173 #define __printf(a, b) __attribute__((__format__(printf, a, b))) 174 #define __scanf(a, b) __attribute__((__format__(scanf, a, b))) 175 176 /* 177 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute 178 * clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline 179 */ 180 #define __gnu_inline __attribute__((__gnu_inline__)) 181 182 /* 183 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute 184 * clang: https://clang.llvm.org/docs/AttributeReference.html#malloc 185 */ 186 #define __malloc __attribute__((__malloc__)) 187 188 /* 189 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute 190 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute 191 */ 192 #define __mode(x) __attribute__((__mode__(x))) 193 194 /* 195 * Optional: only supported since gcc >= 7 196 * 197 * gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86 198 * clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers 199 */ 200 #if __has_attribute(__no_caller_saved_registers__) 201 # define __no_caller_saved_registers __attribute__((__no_caller_saved_registers__)) 202 #else 203 # define __no_caller_saved_registers 204 #endif 205 206 /* 207 * Optional: not supported by clang 208 * 209 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute 210 */ 211 #if __has_attribute(__noclone__) 212 # define __noclone __attribute__((__noclone__)) 213 #else 214 # define __noclone 215 #endif 216 217 /* 218 * Add the pseudo keyword 'fallthrough' so case statement blocks 219 * must end with any of these keywords: 220 * break; 221 * fallthrough; 222 * continue; 223 * goto <label>; 224 * return [expression]; 225 * 226 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes 227 */ 228 #if __has_attribute(__fallthrough__) 229 # define fallthrough __attribute__((__fallthrough__)) 230 #else 231 # define fallthrough do {} while (0) /* fallthrough */ 232 #endif 233 234 /* 235 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes 236 * clang: https://clang.llvm.org/docs/AttributeReference.html#flatten 237 */ 238 # define __flatten __attribute__((flatten)) 239 240 /* 241 * Note the missing underscores. 242 * 243 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute 244 * clang: mentioned 245 */ 246 #define noinline __attribute__((__noinline__)) 247 248 /* 249 * Optional: only supported since gcc >= 8 250 * Optional: not supported by clang 251 * Optional: not supported by icc 252 * 253 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute 254 */ 255 #if __has_attribute(__nonstring__) 256 # define __nonstring __attribute__((__nonstring__)) 257 #else 258 # define __nonstring 259 #endif 260 261 /* 262 * Optional: only supported since GCC >= 7.1, clang >= 13.0. 263 * 264 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fprofile_005finstrument_005ffunction-function-attribute 265 * clang: https://clang.llvm.org/docs/AttributeReference.html#no-profile-instrument-function 266 */ 267 #if __has_attribute(__no_profile_instrument_function__) 268 # define __no_profile __attribute__((__no_profile_instrument_function__)) 269 #else 270 # define __no_profile 271 #endif 272 273 /* 274 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute 275 * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn 276 * clang: https://clang.llvm.org/docs/AttributeReference.html#id1 277 */ 278 #define __noreturn __attribute__((__noreturn__)) 279 280 /* 281 * Optional: not supported by gcc. 282 * Optional: not supported by icc. 283 * 284 * clang: https://clang.llvm.org/docs/AttributeReference.html#overloadable 285 */ 286 #if __has_attribute(__overloadable__) 287 # define __overloadable __attribute__((__overloadable__)) 288 #else 289 # define __overloadable 290 #endif 291 292 /* 293 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute 294 * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute 295 */ 296 #define __packed __attribute__((__packed__)) 297 298 /* 299 * Note: the "type" argument should match any __builtin_object_size(p, type) usage. 300 * 301 * Optional: not supported by gcc. 302 * Optional: not supported by icc. 303 * 304 * clang: https://clang.llvm.org/docs/AttributeReference.html#pass-object-size-pass-dynamic-object-size 305 */ 306 #if __has_attribute(__pass_object_size__) 307 # define __pass_object_size(type) __attribute__((__pass_object_size__(type))) 308 #else 309 # define __pass_object_size(type) 310 #endif 311 312 /* 313 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute 314 */ 315 #define __pure __attribute__((__pure__)) 316 317 /* 318 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute 319 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute 320 * clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate 321 */ 322 #define __section(section) __attribute__((__section__(section))) 323 324 /* 325 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute 326 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute 327 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute 328 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute 329 * clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused 330 */ 331 #define __always_unused __attribute__((__unused__)) 332 #define __maybe_unused __attribute__((__unused__)) 333 334 /* 335 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute 336 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute 337 */ 338 #define __used __attribute__((__used__)) 339 340 /* 341 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warn_005funused_005fresult-function-attribute 342 * clang: https://clang.llvm.org/docs/AttributeReference.html#nodiscard-warn-unused-result 343 */ 344 #define __must_check __attribute__((__warn_unused_result__)) 345 346 /* 347 * Optional: only supported since clang >= 14.0 348 * 349 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warning-function-attribute 350 */ 351 #if __has_attribute(__warning__) 352 # define __compiletime_warning(msg) __attribute__((__warning__(msg))) 353 #else 354 # define __compiletime_warning(msg) 355 #endif 356 357 /* 358 * Optional: only supported since clang >= 14.0 359 * 360 * clang: https://clang.llvm.org/docs/AttributeReference.html#disable-sanitizer-instrumentation 361 * 362 * disable_sanitizer_instrumentation is not always similar to 363 * no_sanitize((<sanitizer-name>)): the latter may still let specific sanitizers 364 * insert code into functions to prevent false positives. Unlike that, 365 * disable_sanitizer_instrumentation prevents all kinds of instrumentation to 366 * functions with the attribute. 367 */ 368 #if __has_attribute(disable_sanitizer_instrumentation) 369 # define __disable_sanitizer_instrumentation \ 370 __attribute__((disable_sanitizer_instrumentation)) 371 #else 372 # define __disable_sanitizer_instrumentation 373 #endif 374 375 /* 376 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute 377 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute 378 */ 379 #define __weak __attribute__((__weak__)) 380 381 /* 382 * Used by functions that use '__builtin_return_address'. These function 383 * don't want to be splited or made inline, which can make 384 * the '__builtin_return_address' get unexpected address. 385 */ 386 #define __fix_address noinline __noclone 387 388 #endif /* __LINUX_COMPILER_ATTRIBUTES_H */ 389