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 * Force always-inline if the user requests it so via the .config, 70 * or if gcc is too old. 71 * GCC does not warn about unused static inline functions for 72 * -Wunused-function. This turns out to avoid the need for complex #ifdef 73 * directives. Suppress the warning in clang as well by using "unused" 74 * function attribute, which is redundant but not harmful for gcc. 75 */ 76 #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ 77 !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) 78 #define inline inline __attribute__((always_inline,unused)) notrace 79 #define __inline__ __inline__ __attribute__((always_inline,unused)) notrace 80 #define __inline __inline __attribute__((always_inline,unused)) notrace 81 #else 82 /* A lot of inline functions can cause havoc with function tracing */ 83 #define inline inline __attribute__((unused)) notrace 84 #define __inline__ __inline__ __attribute__((unused)) notrace 85 #define __inline __inline __attribute__((unused)) notrace 86 #endif 87 88 #define __always_inline inline __attribute__((always_inline)) 89 #define noinline __attribute__((noinline)) 90 91 #define __deprecated __attribute__((deprecated)) 92 #define __packed __attribute__((packed)) 93 #define __weak __attribute__((weak)) 94 #define __alias(symbol) __attribute__((alias(#symbol))) 95 96 /* 97 * it doesn't make sense on ARM (currently the only user of __naked) 98 * to trace naked functions because then mcount is called without 99 * stack and frame pointer being set up and there is no chance to 100 * restore the lr register to the value before mcount was called. 101 * 102 * The asm() bodies of naked functions often depend on standard calling 103 * conventions, therefore they must be noinline and noclone. 104 * 105 * GCC 4.[56] currently fail to enforce this, so we must do so ourselves. 106 * See GCC PR44290. 107 */ 108 #define __naked __attribute__((naked)) noinline __noclone notrace 109 110 #define __noreturn __attribute__((noreturn)) 111 112 /* 113 * From the GCC manual: 114 * 115 * Many functions have no effects except the return value and their 116 * return value depends only on the parameters and/or global 117 * variables. Such a function can be subject to common subexpression 118 * elimination and loop optimization just as an arithmetic operator 119 * would be. 120 * [...] 121 */ 122 #define __pure __attribute__((pure)) 123 #define __aligned(x) __attribute__((aligned(x))) 124 #define __aligned_largest __attribute__((aligned)) 125 #define __printf(a, b) __attribute__((format(printf, a, b))) 126 #define __scanf(a, b) __attribute__((format(scanf, a, b))) 127 #define __attribute_const__ __attribute__((__const__)) 128 #define __maybe_unused __attribute__((unused)) 129 #define __always_unused __attribute__((unused)) 130 #define __mode(x) __attribute__((mode(x))) 131 132 /* gcc version specific checks */ 133 134 #if GCC_VERSION < 30200 135 # error Sorry, your compiler is too old - please upgrade it. 136 #endif 137 138 #if GCC_VERSION < 30300 139 # define __used __attribute__((__unused__)) 140 #else 141 # define __used __attribute__((__used__)) 142 #endif 143 144 #ifdef CONFIG_GCOV_KERNEL 145 # if GCC_VERSION < 30400 146 # error "GCOV profiling support for gcc versions below 3.4 not included" 147 # endif /* __GNUC_MINOR__ */ 148 #endif /* CONFIG_GCOV_KERNEL */ 149 150 #if GCC_VERSION >= 30400 151 #define __must_check __attribute__((warn_unused_result)) 152 #define __malloc __attribute__((__malloc__)) 153 #endif 154 155 #if GCC_VERSION >= 40000 156 157 /* GCC 4.1.[01] miscompiles __weak */ 158 #ifdef __KERNEL__ 159 # if GCC_VERSION >= 40100 && GCC_VERSION <= 40101 160 # error Your version of gcc miscompiles the __weak directive 161 # endif 162 #endif 163 164 #define __used __attribute__((__used__)) 165 #define __compiler_offsetof(a, b) \ 166 __builtin_offsetof(a, b) 167 168 #if GCC_VERSION >= 40100 169 # define __compiletime_object_size(obj) __builtin_object_size(obj, 0) 170 #endif 171 172 #if GCC_VERSION >= 40300 173 /* Mark functions as cold. gcc will assume any path leading to a call 174 * to them will be unlikely. This means a lot of manual unlikely()s 175 * are unnecessary now for any paths leading to the usual suspects 176 * like BUG(), printk(), panic() etc. [but let's keep them for now for 177 * older compilers] 178 * 179 * Early snapshots of gcc 4.3 don't support this and we can't detect this 180 * in the preprocessor, but we can live with this because they're unreleased. 181 * Maketime probing would be overkill here. 182 * 183 * gcc also has a __attribute__((__hot__)) to move hot functions into 184 * a special section, but I don't see any sense in this right now in 185 * the kernel context 186 */ 187 #define __cold __attribute__((__cold__)) 188 189 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__) 190 191 #ifndef __CHECKER__ 192 # define __compiletime_warning(message) __attribute__((warning(message))) 193 # define __compiletime_error(message) __attribute__((error(message))) 194 #endif /* __CHECKER__ */ 195 #endif /* GCC_VERSION >= 40300 */ 196 197 #if GCC_VERSION >= 40400 198 #define __optimize(level) __attribute__((__optimize__(level))) 199 #define __nostackprotector __optimize("no-stack-protector") 200 #endif /* GCC_VERSION >= 40400 */ 201 202 #if GCC_VERSION >= 40500 203 204 #ifndef __CHECKER__ 205 #ifdef LATENT_ENTROPY_PLUGIN 206 #define __latent_entropy __attribute__((latent_entropy)) 207 #endif 208 #endif 209 210 /* 211 * Mark a position in code as unreachable. This can be used to 212 * suppress control flow warnings after asm blocks that transfer 213 * control elsewhere. 214 * 215 * Early snapshots of gcc 4.5 don't support this and we can't detect 216 * this in the preprocessor, but we can live with this because they're 217 * unreleased. Really, we need to have autoconf for the kernel. 218 */ 219 #define unreachable() \ 220 do { annotate_unreachable(); __builtin_unreachable(); } while (0) 221 222 /* Mark a function definition as prohibited from being cloned. */ 223 #define __noclone __attribute__((__noclone__, __optimize__("no-tracer"))) 224 225 #if defined(RANDSTRUCT_PLUGIN) && !defined(__CHECKER__) 226 #define __randomize_layout __attribute__((randomize_layout)) 227 #define __no_randomize_layout __attribute__((no_randomize_layout)) 228 #endif 229 230 #endif /* GCC_VERSION >= 40500 */ 231 232 #if GCC_VERSION >= 40600 233 234 /* 235 * When used with Link Time Optimization, gcc can optimize away C functions or 236 * variables which are referenced only from assembly code. __visible tells the 237 * optimizer that something else uses this function or variable, thus preventing 238 * this. 239 */ 240 #define __visible __attribute__((externally_visible)) 241 242 /* 243 * RANDSTRUCT_PLUGIN wants to use an anonymous struct, but it is only 244 * possible since GCC 4.6. To provide as much build testing coverage 245 * as possible, this is used for all GCC 4.6+ builds, and not just on 246 * RANDSTRUCT_PLUGIN builds. 247 */ 248 #define randomized_struct_fields_start struct { 249 #define randomized_struct_fields_end } __randomize_layout; 250 251 #endif /* GCC_VERSION >= 40600 */ 252 253 254 #if GCC_VERSION >= 40900 && !defined(__CHECKER__) 255 /* 256 * __assume_aligned(n, k): Tell the optimizer that the returned 257 * pointer can be assumed to be k modulo n. The second argument is 258 * optional (default 0), so we use a variadic macro to make the 259 * shorthand. 260 * 261 * Beware: Do not apply this to functions which may return 262 * ERR_PTRs. Also, it is probably unwise to apply it to functions 263 * returning extra information in the low bits (but in that case the 264 * compiler should see some alignment anyway, when the return value is 265 * massaged by 'flags = ptr & 3; ptr &= ~3;'). 266 */ 267 #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) 268 #endif 269 270 /* 271 * GCC 'asm goto' miscompiles certain code sequences: 272 * 273 * http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670 274 * 275 * Work it around via a compiler barrier quirk suggested by Jakub Jelinek. 276 * 277 * (asm goto is automatically volatile - the naming reflects this.) 278 */ 279 #define asm_volatile_goto(x...) do { asm goto(x); asm (""); } while (0) 280 281 /* 282 * sparse (__CHECKER__) pretends to be gcc, but can't do constant 283 * folding in __builtin_bswap*() (yet), so don't set these for it. 284 */ 285 #if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP) && !defined(__CHECKER__) 286 #if GCC_VERSION >= 40400 287 #define __HAVE_BUILTIN_BSWAP32__ 288 #define __HAVE_BUILTIN_BSWAP64__ 289 #endif 290 #if GCC_VERSION >= 40800 291 #define __HAVE_BUILTIN_BSWAP16__ 292 #endif 293 #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP && !__CHECKER__ */ 294 295 #if GCC_VERSION >= 70000 296 #define KASAN_ABI_VERSION 5 297 #elif GCC_VERSION >= 50000 298 #define KASAN_ABI_VERSION 4 299 #elif GCC_VERSION >= 40902 300 #define KASAN_ABI_VERSION 3 301 #endif 302 303 #if GCC_VERSION >= 40902 304 /* 305 * Tell the compiler that address safety instrumentation (KASAN) 306 * should not be applied to that function. 307 * Conflicts with inlining: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 308 */ 309 #define __no_sanitize_address __attribute__((no_sanitize_address)) 310 #endif 311 312 #if GCC_VERSION >= 50100 313 /* 314 * Mark structures as requiring designated initializers. 315 * https://gcc.gnu.org/onlinedocs/gcc/Designated-Inits.html 316 */ 317 #define __designated_init __attribute__((designated_init)) 318 #endif 319 320 #endif /* gcc version >= 40000 specific checks */ 321 322 #if !defined(__noclone) 323 #define __noclone /* not needed */ 324 #endif 325 326 #if !defined(__no_sanitize_address) 327 #define __no_sanitize_address 328 #endif 329 330 /* 331 * A trick to suppress uninitialized variable warning without generating any 332 * code 333 */ 334 #define uninitialized_var(x) x = x 335