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 #ifndef barrier_data 173 # define barrier_data(ptr) barrier() 174 #endif 175 176 /* Unreachable code */ 177 #ifndef unreachable 178 # define unreachable() do { } while (1) 179 #endif 180 181 #ifndef RELOC_HIDE 182 # define RELOC_HIDE(ptr, off) \ 183 ({ unsigned long __ptr; \ 184 __ptr = (unsigned long) (ptr); \ 185 (typeof(ptr)) (__ptr + (off)); }) 186 #endif 187 188 #ifndef OPTIMIZER_HIDE_VAR 189 #define OPTIMIZER_HIDE_VAR(var) barrier() 190 #endif 191 192 /* Not-quite-unique ID. */ 193 #ifndef __UNIQUE_ID 194 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 195 #endif 196 197 #include <uapi/linux/types.h> 198 199 static __always_inline void __read_once_size(const volatile void *p, void *res, int size) 200 { 201 switch (size) { 202 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; 203 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; 204 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; 205 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; 206 default: 207 barrier(); 208 __builtin_memcpy((void *)res, (const void *)p, size); 209 barrier(); 210 } 211 } 212 213 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 214 { 215 switch (size) { 216 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 217 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 218 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 219 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 220 default: 221 barrier(); 222 __builtin_memcpy((void *)p, (const void *)res, size); 223 barrier(); 224 } 225 } 226 227 /* 228 * Prevent the compiler from merging or refetching reads or writes. The 229 * compiler is also forbidden from reordering successive instances of 230 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the 231 * compiler is aware of some particular ordering. One way to make the 232 * compiler aware of ordering is to put the two invocations of READ_ONCE, 233 * WRITE_ONCE or ACCESS_ONCE() in different C statements. 234 * 235 * In contrast to ACCESS_ONCE these two macros will also work on aggregate 236 * data types like structs or unions. If the size of the accessed data 237 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) 238 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a 239 * compile-time warning. 240 * 241 * Their two major use cases are: (1) Mediating communication between 242 * process-level code and irq/NMI handlers, all running on the same CPU, 243 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 244 * mutilate accesses that either do not require ordering or that interact 245 * with an explicit memory barrier or atomic instruction that provides the 246 * required ordering. 247 */ 248 249 #define READ_ONCE(x) \ 250 ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; }) 251 252 #define WRITE_ONCE(x, val) \ 253 ({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; __write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; }) 254 255 /** 256 * READ_ONCE_CTRL - Read a value heading a control dependency 257 * @x: The value to be read, heading the control dependency 258 * 259 * Control dependencies are tricky. See Documentation/memory-barriers.txt 260 * for important information on how to use them. Note that in many cases, 261 * use of smp_load_acquire() will be much simpler. Control dependencies 262 * should be avoided except on the hottest of hotpaths. 263 */ 264 #define READ_ONCE_CTRL(x) \ 265 ({ \ 266 typeof(x) __val = READ_ONCE(x); \ 267 smp_read_barrier_depends(); /* Enforce control dependency. */ \ 268 __val; \ 269 }) 270 271 #endif /* __KERNEL__ */ 272 273 #endif /* __ASSEMBLY__ */ 274 275 #ifdef __KERNEL__ 276 /* 277 * Allow us to mark functions as 'deprecated' and have gcc emit a nice 278 * warning for each use, in hopes of speeding the functions removal. 279 * Usage is: 280 * int __deprecated foo(void) 281 */ 282 #ifndef __deprecated 283 # define __deprecated /* unimplemented */ 284 #endif 285 286 #ifdef MODULE 287 #define __deprecated_for_modules __deprecated 288 #else 289 #define __deprecated_for_modules 290 #endif 291 292 #ifndef __must_check 293 #define __must_check 294 #endif 295 296 #ifndef CONFIG_ENABLE_MUST_CHECK 297 #undef __must_check 298 #define __must_check 299 #endif 300 #ifndef CONFIG_ENABLE_WARN_DEPRECATED 301 #undef __deprecated 302 #undef __deprecated_for_modules 303 #define __deprecated 304 #define __deprecated_for_modules 305 #endif 306 307 /* 308 * Allow us to avoid 'defined but not used' warnings on functions and data, 309 * as well as force them to be emitted to the assembly file. 310 * 311 * As of gcc 3.4, static functions that are not marked with attribute((used)) 312 * may be elided from the assembly file. As of gcc 3.4, static data not so 313 * marked will not be elided, but this may change in a future gcc version. 314 * 315 * NOTE: Because distributions shipped with a backported unit-at-a-time 316 * compiler in gcc 3.3, we must define __used to be __attribute__((used)) 317 * for gcc >=3.3 instead of 3.4. 318 * 319 * In prior versions of gcc, such functions and data would be emitted, but 320 * would be warned about except with attribute((unused)). 321 * 322 * Mark functions that are referenced only in inline assembly as __used so 323 * the code is emitted even though it appears to be unreferenced. 324 */ 325 #ifndef __used 326 # define __used /* unimplemented */ 327 #endif 328 329 #ifndef __maybe_unused 330 # define __maybe_unused /* unimplemented */ 331 #endif 332 333 #ifndef __always_unused 334 # define __always_unused /* unimplemented */ 335 #endif 336 337 #ifndef noinline 338 #define noinline 339 #endif 340 341 /* 342 * Rather then using noinline to prevent stack consumption, use 343 * noinline_for_stack instead. For documentation reasons. 344 */ 345 #define noinline_for_stack noinline 346 347 #ifndef __always_inline 348 #define __always_inline inline 349 #endif 350 351 #endif /* __KERNEL__ */ 352 353 /* 354 * From the GCC manual: 355 * 356 * Many functions do not examine any values except their arguments, 357 * and have no effects except the return value. Basically this is 358 * just slightly more strict class than the `pure' attribute above, 359 * since function is not allowed to read global memory. 360 * 361 * Note that a function that has pointer arguments and examines the 362 * data pointed to must _not_ be declared `const'. Likewise, a 363 * function that calls a non-`const' function usually must not be 364 * `const'. It does not make sense for a `const' function to return 365 * `void'. 366 */ 367 #ifndef __attribute_const__ 368 # define __attribute_const__ /* unimplemented */ 369 #endif 370 371 /* 372 * Tell gcc if a function is cold. The compiler will assume any path 373 * directly leading to the call is unlikely. 374 */ 375 376 #ifndef __cold 377 #define __cold 378 #endif 379 380 /* Simple shorthand for a section definition */ 381 #ifndef __section 382 # define __section(S) __attribute__ ((__section__(#S))) 383 #endif 384 385 #ifndef __visible 386 #define __visible 387 #endif 388 389 /* Are two types/vars the same type (ignoring qualifiers)? */ 390 #ifndef __same_type 391 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) 392 #endif 393 394 /* Is this type a native word size -- useful for atomic operations */ 395 #ifndef __native_word 396 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) 397 #endif 398 399 /* Compile time object size, -1 for unknown */ 400 #ifndef __compiletime_object_size 401 # define __compiletime_object_size(obj) -1 402 #endif 403 #ifndef __compiletime_warning 404 # define __compiletime_warning(message) 405 #endif 406 #ifndef __compiletime_error 407 # define __compiletime_error(message) 408 /* 409 * Sparse complains of variable sized arrays due to the temporary variable in 410 * __compiletime_assert. Unfortunately we can't just expand it out to make 411 * sparse see a constant array size without breaking compiletime_assert on old 412 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. 413 */ 414 # ifndef __CHECKER__ 415 # define __compiletime_error_fallback(condition) \ 416 do { ((void)sizeof(char[1 - 2 * condition])); } while (0) 417 # endif 418 #endif 419 #ifndef __compiletime_error_fallback 420 # define __compiletime_error_fallback(condition) do { } while (0) 421 #endif 422 423 #define __compiletime_assert(condition, msg, prefix, suffix) \ 424 do { \ 425 bool __cond = !(condition); \ 426 extern void prefix ## suffix(void) __compiletime_error(msg); \ 427 if (__cond) \ 428 prefix ## suffix(); \ 429 __compiletime_error_fallback(__cond); \ 430 } while (0) 431 432 #define _compiletime_assert(condition, msg, prefix, suffix) \ 433 __compiletime_assert(condition, msg, prefix, suffix) 434 435 /** 436 * compiletime_assert - break build and emit msg if condition is false 437 * @condition: a compile-time constant condition to check 438 * @msg: a message to emit if condition is false 439 * 440 * In tradition of POSIX assert, this macro will break the build if the 441 * supplied condition is *false*, emitting the supplied error message if the 442 * compiler has support to do so. 443 */ 444 #define compiletime_assert(condition, msg) \ 445 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 446 447 #define compiletime_assert_atomic_type(t) \ 448 compiletime_assert(__native_word(t), \ 449 "Need native word sized stores/loads for atomicity.") 450 451 /* 452 * Prevent the compiler from merging or refetching accesses. The compiler 453 * is also forbidden from reordering successive instances of ACCESS_ONCE(), 454 * but only when the compiler is aware of some particular ordering. One way 455 * to make the compiler aware of ordering is to put the two invocations of 456 * ACCESS_ONCE() in different C statements. 457 * 458 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE 459 * on a union member will work as long as the size of the member matches the 460 * size of the union and the size is smaller than word size. 461 * 462 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication 463 * between process-level code and irq/NMI handlers, all running on the same CPU, 464 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 465 * mutilate accesses that either do not require ordering or that interact 466 * with an explicit memory barrier or atomic instruction that provides the 467 * required ordering. 468 * 469 * If possible use READ_ONCE()/WRITE_ONCE() instead. 470 */ 471 #define __ACCESS_ONCE(x) ({ \ 472 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \ 473 (volatile typeof(x) *)&(x); }) 474 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) 475 476 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */ 477 #ifdef CONFIG_KPROBES 478 # define __kprobes __attribute__((__section__(".kprobes.text"))) 479 # define nokprobe_inline __always_inline 480 #else 481 # define __kprobes 482 # define nokprobe_inline inline 483 #endif 484 #endif /* __LINUX_COMPILER_H */ 485