1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __LINUX_COMPILER_TYPES_H 3 #error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead." 4 #endif 5 6 /* 7 * Common definitions for all gcc versions go here. 8 */ 9 #define GCC_VERSION (__GNUC__ * 10000 \ 10 + __GNUC_MINOR__ * 100 \ 11 + __GNUC_PATCHLEVEL__) 12 13 /* Optimization barrier */ 14 15 /* The "volatile" is due to gcc bugs */ 16 #define barrier() __asm__ __volatile__("": : :"memory") 17 /* 18 * This version is i.e. to prevent dead stores elimination on @ptr 19 * where gcc and llvm may behave differently when otherwise using 20 * normal barrier(): while gcc behavior gets along with a normal 21 * barrier(), llvm needs an explicit input variable to be assumed 22 * clobbered. The issue is as follows: while the inline asm might 23 * access any memory it wants, the compiler could have fit all of 24 * @ptr into memory registers instead, and since @ptr never escaped 25 * from that, it proved that the inline asm wasn't touching any of 26 * it. This version works well with both compilers, i.e. we're telling 27 * the compiler that the inline asm absolutely may see the contents 28 * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495 29 */ 30 #define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory") 31 32 /* 33 * This macro obfuscates arithmetic on a variable address so that gcc 34 * shouldn't recognize the original var, and make assumptions about it. 35 * 36 * This is needed because the C standard makes it undefined to do 37 * pointer arithmetic on "objects" outside their boundaries and the 38 * gcc optimizers assume this is the case. In particular they 39 * assume such arithmetic does not wrap. 40 * 41 * A miscompilation has been observed because of this on PPC. 42 * To work around it we hide the relationship of the pointer and the object 43 * using this macro. 44 * 45 * Versions of the ppc64 compiler before 4.1 had a bug where use of 46 * RELOC_HIDE could trash r30. The bug can be worked around by changing 47 * the inline assembly constraint from =g to =r, in this particular 48 * case either is valid. 49 */ 50 #define RELOC_HIDE(ptr, off) \ 51 ({ \ 52 unsigned long __ptr; \ 53 __asm__ ("" : "=r"(__ptr) : "0"(ptr)); \ 54 (typeof(ptr)) (__ptr + (off)); \ 55 }) 56 57 /* Make the optimizer believe the variable can be manipulated arbitrarily. */ 58 #define OPTIMIZER_HIDE_VAR(var) \ 59 __asm__ ("" : "=r" (var) : "0" (var)) 60 61 #ifdef __CHECKER__ 62 #define __must_be_array(a) 0 63 #else 64 /* &a[0] degrades to a pointer: a different type from an array */ 65 #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) 66 #endif 67 68 /* 69 * Feature detection for gnu_inline (gnu89 extern inline semantics). Either 70 * __GNUC_STDC_INLINE__ is defined (not using gnu89 extern inline semantics, 71 * and we opt in to the gnu89 semantics), or __GNUC_STDC_INLINE__ is not 72 * defined so the gnu89 semantics are the default. 73 */ 74 #ifdef __GNUC_STDC_INLINE__ 75 # define __gnu_inline __attribute__((gnu_inline)) 76 #else 77 # define __gnu_inline 78 #endif 79 80 /* 81 * Force always-inline if the user requests it so via the .config, 82 * or if gcc is too old. 83 * GCC does not warn about unused static inline functions for 84 * -Wunused-function. This turns out to avoid the need for complex #ifdef 85 * directives. Suppress the warning in clang as well by using "unused" 86 * function attribute, which is redundant but not harmful for gcc. 87 * Prefer gnu_inline, so that extern inline functions do not emit an 88 * externally visible function. This makes extern inline behave as per gnu89 89 * semantics rather than c99. This prevents multiple symbol definition errors 90 * of extern inline functions at link time. 91 * A lot of inline functions can cause havoc with function tracing. 92 */ 93 #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ 94 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) 95 #define inline \ 96 inline __attribute__((always_inline, unused)) notrace __gnu_inline 97 #else 98 #define inline inline __attribute__((unused)) notrace __gnu_inline 99 #endif 100 101 #define __inline__ inline 102 #define __inline inline 103 #define __always_inline inline __attribute__((always_inline)) 104 #define noinline __attribute__((noinline)) 105 106 #define __deprecated __attribute__((deprecated)) 107 #define __packed __attribute__((packed)) 108 #define __weak __attribute__((weak)) 109 #define __alias(symbol) __attribute__((alias(#symbol))) 110 111 #ifdef CONFIG_RETPOLINE 112 #define __noretpoline __attribute__((indirect_branch("keep"))) 113 #endif 114 115 /* 116 * it doesn't make sense on ARM (currently the only user of __naked) 117 * to trace naked functions because then mcount is called without 118 * stack and frame pointer being set up and there is no chance to 119 * restore the lr register to the value before mcount was called. 120 * 121 * The asm() bodies of naked functions often depend on standard calling 122 * conventions, therefore they must be noinline and noclone. 123 * 124 * GCC 4.[56] currently fail to enforce this, so we must do so ourselves. 125 * See GCC PR44290. 126 */ 127 #define __naked __attribute__((naked)) noinline __noclone notrace 128 129 #define __noreturn __attribute__((noreturn)) 130 131 /* 132 * From the GCC manual: 133 * 134 * Many functions have no effects except the return value and their 135 * return value depends only on the parameters and/or global 136 * variables. Such a function can be subject to common subexpression 137 * elimination and loop optimization just as an arithmetic operator 138 * would be. 139 * [...] 140 */ 141 #define __pure __attribute__((pure)) 142 #define __aligned(x) __attribute__((aligned(x))) 143 #define __aligned_largest __attribute__((aligned)) 144 #define __printf(a, b) __attribute__((format(printf, a, b))) 145 #define __scanf(a, b) __attribute__((format(scanf, a, b))) 146 #define __attribute_const__ __attribute__((__const__)) 147 #define __maybe_unused __attribute__((unused)) 148 #define __always_unused __attribute__((unused)) 149 #define __mode(x) __attribute__((mode(x))) 150 151 /* gcc version specific checks */ 152 153 #if GCC_VERSION < 30200 154 # error Sorry, your compiler is too old - please upgrade it. 155 #endif 156 157 #if GCC_VERSION < 30300 158 # define __used __attribute__((__unused__)) 159 #else 160 # define __used __attribute__((__used__)) 161 #endif 162 163 #ifdef CONFIG_GCOV_KERNEL 164 # if GCC_VERSION < 30400 165 # error "GCOV profiling support for gcc versions below 3.4 not included" 166 # endif /* __GNUC_MINOR__ */ 167 #endif /* CONFIG_GCOV_KERNEL */ 168 169 #if GCC_VERSION >= 30400 170 #define __must_check __attribute__((warn_unused_result)) 171 #define __malloc __attribute__((__malloc__)) 172 #endif 173 174 #if GCC_VERSION >= 40000 175 176 /* GCC 4.1.[01] miscompiles __weak */ 177 #ifdef __KERNEL__ 178 # if GCC_VERSION >= 40100 && GCC_VERSION <= 40101 179 # error Your version of gcc miscompiles the __weak directive 180 # endif 181 #endif 182 183 #define __used __attribute__((__used__)) 184 #define __compiler_offsetof(a, b) \ 185 __builtin_offsetof(a, b) 186 187 #if GCC_VERSION >= 40100 188 # define __compiletime_object_size(obj) __builtin_object_size(obj, 0) 189 #endif 190 191 #if GCC_VERSION >= 40300 192 /* Mark functions as cold. gcc will assume any path leading to a call 193 * to them will be unlikely. This means a lot of manual unlikely()s 194 * are unnecessary now for any paths leading to the usual suspects 195 * like BUG(), printk(), panic() etc. [but let's keep them for now for 196 * older compilers] 197 * 198 * Early snapshots of gcc 4.3 don't support this and we can't detect this 199 * in the preprocessor, but we can live with this because they're unreleased. 200 * Maketime probing would be overkill here. 201 * 202 * gcc also has a __attribute__((__hot__)) to move hot functions into 203 * a special section, but I don't see any sense in this right now in 204 * the kernel context 205 */ 206 #define __cold __attribute__((__cold__)) 207 208 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) 209 210 #ifndef __CHECKER__ 211 # define __compiletime_warning(message) __attribute__((warning(message))) 212 # define __compiletime_error(message) __attribute__((error(message))) 213 #endif /* __CHECKER__ */ 214 #endif /* GCC_VERSION >= 40300 */ 215 216 #if GCC_VERSION >= 40400 217 #define __optimize(level) __attribute__((__optimize__(level))) 218 #define __nostackprotector __optimize("no-stack-protector") 219 #endif /* GCC_VERSION >= 40400 */ 220 221 #if GCC_VERSION >= 40500 222 223 #ifndef __CHECKER__ 224 #ifdef LATENT_ENTROPY_PLUGIN 225 #define __latent_entropy __attribute__((latent_entropy)) 226 #endif 227 #endif 228 229 /* 230 * calling noreturn functions, __builtin_unreachable() and __builtin_trap() 231 * confuse the stack allocation in gcc, leading to overly large stack 232 * frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 233 * 234 * Adding an empty inline assembly before it works around the problem 235 */ 236 #define barrier_before_unreachable() asm volatile("") 237 238 /* 239 * Mark a position in code as unreachable. This can be used to 240 * suppress control flow warnings after asm blocks that transfer 241 * control elsewhere. 242 * 243 * Early snapshots of gcc 4.5 don't support this and we can't detect 244 * this in the preprocessor, but we can live with this because they're 245 * unreleased. Really, we need to have autoconf for the kernel. 246 */ 247 #define unreachable() \ 248 do { \ 249 annotate_unreachable(); \ 250 barrier_before_unreachable(); \ 251 __builtin_unreachable(); \ 252 } while (0) 253 254 /* Mark a function definition as prohibited from being cloned. */ 255 #define __noclone __attribute__((__noclone__, __optimize__("no-tracer"))) 256 257 #ifdef RANDSTRUCT_PLUGIN 258 #define __randomize_layout __attribute__((randomize_layout)) 259 #define __no_randomize_layout __attribute__((no_randomize_layout)) 260 /* This anon struct can add padding, so only enable it under randstruct. */ 261 #define randomized_struct_fields_start struct { 262 #define randomized_struct_fields_end } __randomize_layout; 263 #endif 264 265 #endif /* GCC_VERSION >= 40500 */ 266 267 #if GCC_VERSION >= 40600 268 269 /* 270 * When used with Link Time Optimization, gcc can optimize away C functions or 271 * variables which are referenced only from assembly code. __visible tells the 272 * optimizer that something else uses this function or variable, thus preventing 273 * this. 274 */ 275 #define __visible __attribute__((externally_visible)) 276 277 #endif /* GCC_VERSION >= 40600 */ 278 279 280 #if GCC_VERSION >= 40900 && !defined(__CHECKER__) 281 /* 282 * __assume_aligned(n, k): Tell the optimizer that the returned 283 * pointer can be assumed to be k modulo n. The second argument is 284 * optional (default 0), so we use a variadic macro to make the 285 * shorthand. 286 * 287 * Beware: Do not apply this to functions which may return 288 * ERR_PTRs. Also, it is probably unwise to apply it to functions 289 * returning extra information in the low bits (but in that case the 290 * compiler should see some alignment anyway, when the return value is 291 * massaged by 'flags = ptr & 3; ptr &= ~3;'). 292 */ 293 #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) 294 #endif 295 296 /* 297 * GCC 'asm goto' miscompiles certain code sequences: 298 * 299 * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 300 * 301 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek. 302 * 303 * (asm goto is automatically volatile - the naming reflects this.) 304 */ 305 #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) 306 307 /* 308 * sparse (__CHECKER__) pretends to be gcc, but can't do constant 309 * folding in __builtin_bswap*() (yet), so don't set these for it. 310 */ 311 #if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__) 312 #if GCC_VERSION >= 40400 313 #define __HAVE_BUILTIN_BSWAP32__ 314 #define __HAVE_BUILTIN_BSWAP64__ 315 #endif 316 #if GCC_VERSION >= 40800 317 #define __HAVE_BUILTIN_BSWAP16__ 318 #endif 319 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */ 320 321 #if GCC_VERSION >= 70000 322 #define KASAN_ABI_VERSION 5 323 #elif GCC_VERSION >= 50000 324 #define KASAN_ABI_VERSION 4 325 #elif GCC_VERSION >= 40902 326 #define KASAN_ABI_VERSION 3 327 #endif 328 329 #if GCC_VERSION >= 40902 330 /* 331 * Tell the compiler that address safety instrumentation (KASAN) 332 * should not be applied to that function. 333 * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 334 */ 335 #define __no_sanitize_address __attribute__((no_sanitize_address)) 336 #endif 337 338 #if GCC_VERSION >= 50100 339 /* 340 * Mark structures as requiring designated initializers. 341 * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html 342 */ 343 #define __designated_init __attribute__((designated_init)) 344 #endif 345 346 #if GCC_VERSION >= 90100 347 #define __copy(symbol) __attribute__((__copy__(symbol))) 348 #endif 349 350 #endif /* gcc version >= 40000 specific checks */ 351 352 #if !defined(__noclone) 353 #define __noclone /* not needed */ 354 #endif 355 356 #if !defined(__no_sanitize_address) 357 #define __no_sanitize_address 358 #endif 359 360 /* 361 * A trick to suppress uninitialized variable warning without generating any 362 * code 363 */ 364 #define uninitialized_var(x) x = x 365 366 #if GCC_VERSION >= 50100 367 #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1 368 #endif 369