1 #ifndef __LINUX_COMPILER_H 2 #define __LINUX_COMPILER_H 3 4 #ifndef __ASSEMBLY__ 5 6 #ifdef __CHECKER__ 7 # define __user __attribute__((noderef, address_space(1))) 8 # define __kernel __attribute__((address_space(0))) 9 # define __safe __attribute__((safe)) 10 # define __force __attribute__((force)) 11 # define __nocast __attribute__((nocast)) 12 # define __iomem __attribute__((noderef, address_space(2))) 13 # define __must_hold(x) __attribute__((context(x,1,1))) 14 # define __acquires(x) __attribute__((context(x,0,1))) 15 # define __releases(x) __attribute__((context(x,1,0))) 16 # define __acquire(x) __context__(x,1) 17 # define __release(x) __context__(x,-1) 18 # define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0) 19 # define __percpu __attribute__((noderef, address_space(3))) 20 #ifdef CONFIG_SPARSE_RCU_POINTER 21 # define __rcu __attribute__((noderef, address_space(4))) 22 #else 23 # define __rcu 24 #endif 25 extern void __chk_user_ptr(const volatile void __user *); 26 extern void __chk_io_ptr(const volatile void __iomem *); 27 #else 28 # define __user 29 # define __kernel 30 # define __safe 31 # define __force 32 # define __nocast 33 # define __iomem 34 # define __chk_user_ptr(x) (void)0 35 # define __chk_io_ptr(x) (void)0 36 # define __builtin_warning(x, y...) (1) 37 # define __must_hold(x) 38 # define __acquires(x) 39 # define __releases(x) 40 # define __acquire(x) (void)0 41 # define __release(x) (void)0 42 # define __cond_lock(x,c) (c) 43 # define __percpu 44 # define __rcu 45 #endif 46 47 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */ 48 #define ___PASTE(a,b) a##b 49 #define __PASTE(a,b) ___PASTE(a,b) 50 51 #ifdef __KERNEL__ 52 53 #ifdef __GNUC__ 54 #include <linux/compiler-gcc.h> 55 #endif 56 57 #ifdef CC_USING_HOTPATCH 58 #define notrace __attribute__((hotpatch(0,0))) 59 #else 60 #define notrace __attribute__((no_instrument_function)) 61 #endif 62 63 /* Intel compiler defines __GNUC__. So we will overwrite implementations 64 * coming from above header files here 65 */ 66 #ifdef __INTEL_COMPILER 67 # include <linux/compiler-intel.h> 68 #endif 69 70 /* Clang compiler defines __GNUC__. So we will overwrite implementations 71 * coming from above header files here 72 */ 73 #ifdef __clang__ 74 #include <linux/compiler-clang.h> 75 #endif 76 77 /* 78 * Generic compiler-dependent macros required for kernel 79 * build go below this comment. Actual compiler/compiler version 80 * specific implementations come from the above header files 81 */ 82 83 struct ftrace_branch_data { 84 const char *func; 85 const char *file; 86 unsigned line; 87 union { 88 struct { 89 unsigned long correct; 90 unsigned long incorrect; 91 }; 92 struct { 93 unsigned long miss; 94 unsigned long hit; 95 }; 96 unsigned long miss_hit[2]; 97 }; 98 }; 99 100 /* 101 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code 102 * to disable branch tracing on a per file basis. 103 */ 104 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \ 105 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) 106 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); 107 108 #define likely_notrace(x) __builtin_expect(!!(x), 1) 109 #define unlikely_notrace(x) __builtin_expect(!!(x), 0) 110 111 #define __branch_check__(x, expect) ({ \ 112 int ______r; \ 113 static struct ftrace_branch_data \ 114 __attribute__((__aligned__(4))) \ 115 __attribute__((section("_ftrace_annotated_branch"))) \ 116 ______f = { \ 117 .func = __func__, \ 118 .file = __FILE__, \ 119 .line = __LINE__, \ 120 }; \ 121 ______r = likely_notrace(x); \ 122 ftrace_likely_update(&______f, ______r, expect); \ 123 ______r; \ 124 }) 125 126 /* 127 * Using __builtin_constant_p(x) to ignore cases where the return 128 * value is always the same. This idea is taken from a similar patch 129 * written by Daniel Walker. 130 */ 131 # ifndef likely 132 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1)) 133 # endif 134 # ifndef unlikely 135 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0)) 136 # endif 137 138 #ifdef CONFIG_PROFILE_ALL_BRANCHES 139 /* 140 * "Define 'is'", Bill Clinton 141 * "Define 'if'", Steven Rostedt 142 */ 143 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) ) 144 #define __trace_if(cond) \ 145 if (__builtin_constant_p((cond)) ? !!(cond) : \ 146 ({ \ 147 int ______r; \ 148 static struct ftrace_branch_data \ 149 __attribute__((__aligned__(4))) \ 150 __attribute__((section("_ftrace_branch"))) \ 151 ______f = { \ 152 .func = __func__, \ 153 .file = __FILE__, \ 154 .line = __LINE__, \ 155 }; \ 156 ______r = !!(cond); \ 157 ______f.miss_hit[______r]++; \ 158 ______r; \ 159 })) 160 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 161 162 #else 163 # define likely(x) __builtin_expect(!!(x), 1) 164 # define unlikely(x) __builtin_expect(!!(x), 0) 165 #endif 166 167 /* Optimization barrier */ 168 #ifndef barrier 169 # define barrier() __memory_barrier() 170 #endif 171 172 /* Unreachable code */ 173 #ifndef unreachable 174 # define unreachable() do { } while (1) 175 #endif 176 177 #ifndef RELOC_HIDE 178 # define RELOC_HIDE(ptr, off) \ 179 ({ unsigned long __ptr; \ 180 __ptr = (unsigned long) (ptr); \ 181 (typeof(ptr)) (__ptr + (off)); }) 182 #endif 183 184 #ifndef OPTIMIZER_HIDE_VAR 185 #define OPTIMIZER_HIDE_VAR(var) barrier() 186 #endif 187 188 /* Not-quite-unique ID. */ 189 #ifndef __UNIQUE_ID 190 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 191 #endif 192 193 #include <uapi/linux/types.h> 194 195 static __always_inline void __read_once_size(const volatile void *p, void *res, int size) 196 { 197 switch (size) { 198 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; 199 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; 200 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; 201 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; 202 default: 203 barrier(); 204 __builtin_memcpy((void *)res, (const void *)p, size); 205 barrier(); 206 } 207 } 208 209 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 210 { 211 switch (size) { 212 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 213 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 214 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 215 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 216 default: 217 barrier(); 218 __builtin_memcpy((void *)p, (const void *)res, size); 219 barrier(); 220 } 221 } 222 223 /* 224 * Prevent the compiler from merging or refetching reads or writes. The 225 * compiler is also forbidden from reordering successive instances of 226 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the 227 * compiler is aware of some particular ordering. One way to make the 228 * compiler aware of ordering is to put the two invocations of READ_ONCE, 229 * WRITE_ONCE or ACCESS_ONCE() in different C statements. 230 * 231 * In contrast to ACCESS_ONCE these two macros will also work on aggregate 232 * data types like structs or unions. If the size of the accessed data 233 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) 234 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a 235 * compile-time warning. 236 * 237 * Their two major use cases are: (1) Mediating communication between 238 * process-level code and irq/NMI handlers, all running on the same CPU, 239 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 240 * mutilate accesses that either do not require ordering or that interact 241 * with an explicit memory barrier or atomic instruction that provides the 242 * required ordering. 243 */ 244 245 #define READ_ONCE(x) \ 246 ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; }) 247 248 #define WRITE_ONCE(x, val) \ 249 ({ typeof(x) __val = (val); __write_once_size(&(x), &__val, sizeof(__val)); __val; }) 250 251 #endif /* __KERNEL__ */ 252 253 #endif /* __ASSEMBLY__ */ 254 255 #ifdef __KERNEL__ 256 /* 257 * Allow us to mark functions as 'deprecated' and have gcc emit a nice 258 * warning for each use, in hopes of speeding the functions removal. 259 * Usage is: 260 * int __deprecated foo(void) 261 */ 262 #ifndef __deprecated 263 # define __deprecated /* unimplemented */ 264 #endif 265 266 #ifdef MODULE 267 #define __deprecated_for_modules __deprecated 268 #else 269 #define __deprecated_for_modules 270 #endif 271 272 #ifndef __must_check 273 #define __must_check 274 #endif 275 276 #ifndef CONFIG_ENABLE_MUST_CHECK 277 #undef __must_check 278 #define __must_check 279 #endif 280 #ifndef CONFIG_ENABLE_WARN_DEPRECATED 281 #undef __deprecated 282 #undef __deprecated_for_modules 283 #define __deprecated 284 #define __deprecated_for_modules 285 #endif 286 287 /* 288 * Allow us to avoid 'defined but not used' warnings on functions and data, 289 * as well as force them to be emitted to the assembly file. 290 * 291 * As of gcc 3.4, static functions that are not marked with attribute((used)) 292 * may be elided from the assembly file. As of gcc 3.4, static data not so 293 * marked will not be elided, but this may change in a future gcc version. 294 * 295 * NOTE: Because distributions shipped with a backported unit-at-a-time 296 * compiler in gcc 3.3, we must define __used to be __attribute__((used)) 297 * for gcc >=3.3 instead of 3.4. 298 * 299 * In prior versions of gcc, such functions and data would be emitted, but 300 * would be warned about except with attribute((unused)). 301 * 302 * Mark functions that are referenced only in inline assembly as __used so 303 * the code is emitted even though it appears to be unreferenced. 304 */ 305 #ifndef __used 306 # define __used /* unimplemented */ 307 #endif 308 309 #ifndef __maybe_unused 310 # define __maybe_unused /* unimplemented */ 311 #endif 312 313 #ifndef __always_unused 314 # define __always_unused /* unimplemented */ 315 #endif 316 317 #ifndef noinline 318 #define noinline 319 #endif 320 321 /* 322 * Rather then using noinline to prevent stack consumption, use 323 * noinline_for_stack instead. For documentation reasons. 324 */ 325 #define noinline_for_stack noinline 326 327 #ifndef __always_inline 328 #define __always_inline inline 329 #endif 330 331 #endif /* __KERNEL__ */ 332 333 /* 334 * From the GCC manual: 335 * 336 * Many functions do not examine any values except their arguments, 337 * and have no effects except the return value. Basically this is 338 * just slightly more strict class than the `pure' attribute above, 339 * since function is not allowed to read global memory. 340 * 341 * Note that a function that has pointer arguments and examines the 342 * data pointed to must _not_ be declared `const'. Likewise, a 343 * function that calls a non-`const' function usually must not be 344 * `const'. It does not make sense for a `const' function to return 345 * `void'. 346 */ 347 #ifndef __attribute_const__ 348 # define __attribute_const__ /* unimplemented */ 349 #endif 350 351 /* 352 * Tell gcc if a function is cold. The compiler will assume any path 353 * directly leading to the call is unlikely. 354 */ 355 356 #ifndef __cold 357 #define __cold 358 #endif 359 360 /* Simple shorthand for a section definition */ 361 #ifndef __section 362 # define __section(S) __attribute__ ((__section__(#S))) 363 #endif 364 365 #ifndef __visible 366 #define __visible 367 #endif 368 369 /* Are two types/vars the same type (ignoring qualifiers)? */ 370 #ifndef __same_type 371 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) 372 #endif 373 374 /* Is this type a native word size -- useful for atomic operations */ 375 #ifndef __native_word 376 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) 377 #endif 378 379 /* Compile time object size, -1 for unknown */ 380 #ifndef __compiletime_object_size 381 # define __compiletime_object_size(obj) -1 382 #endif 383 #ifndef __compiletime_warning 384 # define __compiletime_warning(message) 385 #endif 386 #ifndef __compiletime_error 387 # define __compiletime_error(message) 388 /* 389 * Sparse complains of variable sized arrays due to the temporary variable in 390 * __compiletime_assert. Unfortunately we can't just expand it out to make 391 * sparse see a constant array size without breaking compiletime_assert on old 392 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. 393 */ 394 # ifndef __CHECKER__ 395 # define __compiletime_error_fallback(condition) \ 396 do { ((void)sizeof(char[1 - 2 * condition])); } while (0) 397 # endif 398 #endif 399 #ifndef __compiletime_error_fallback 400 # define __compiletime_error_fallback(condition) do { } while (0) 401 #endif 402 403 #define __compiletime_assert(condition, msg, prefix, suffix) \ 404 do { \ 405 bool __cond = !(condition); \ 406 extern void prefix ## suffix(void) __compiletime_error(msg); \ 407 if (__cond) \ 408 prefix ## suffix(); \ 409 __compiletime_error_fallback(__cond); \ 410 } while (0) 411 412 #define _compiletime_assert(condition, msg, prefix, suffix) \ 413 __compiletime_assert(condition, msg, prefix, suffix) 414 415 /** 416 * compiletime_assert - break build and emit msg if condition is false 417 * @condition: a compile-time constant condition to check 418 * @msg: a message to emit if condition is false 419 * 420 * In tradition of POSIX assert, this macro will break the build if the 421 * supplied condition is *false*, emitting the supplied error message if the 422 * compiler has support to do so. 423 */ 424 #define compiletime_assert(condition, msg) \ 425 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 426 427 #define compiletime_assert_atomic_type(t) \ 428 compiletime_assert(__native_word(t), \ 429 "Need native word sized stores/loads for atomicity.") 430 431 /* 432 * Prevent the compiler from merging or refetching accesses. The compiler 433 * is also forbidden from reordering successive instances of ACCESS_ONCE(), 434 * but only when the compiler is aware of some particular ordering. One way 435 * to make the compiler aware of ordering is to put the two invocations of 436 * ACCESS_ONCE() in different C statements. 437 * 438 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE 439 * on a union member will work as long as the size of the member matches the 440 * size of the union and the size is smaller than word size. 441 * 442 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication 443 * between process-level code and irq/NMI handlers, all running on the same CPU, 444 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 445 * mutilate accesses that either do not require ordering or that interact 446 * with an explicit memory barrier or atomic instruction that provides the 447 * required ordering. 448 * 449 * If possible use READ_ONCE/ASSIGN_ONCE instead. 450 */ 451 #define __ACCESS_ONCE(x) ({ \ 452 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \ 453 (volatile typeof(x) *)&(x); }) 454 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) 455 456 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */ 457 #ifdef CONFIG_KPROBES 458 # define __kprobes __attribute__((__section__(".kprobes.text"))) 459 # define nokprobe_inline __always_inline 460 #else 461 # define __kprobes 462 # define nokprobe_inline inline 463 #endif 464 #endif /* __LINUX_COMPILER_H */ 465