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 # define __pmem __attribute__((noderef, address_space(5))) 21 #ifdef CONFIG_SPARSE_RCU_POINTER 22 # define __rcu __attribute__((noderef, address_space(4))) 23 #else 24 # define __rcu 25 #endif 26 extern void __chk_user_ptr(const volatile void __user *); 27 extern void __chk_io_ptr(const volatile void __iomem *); 28 #else 29 # define __user 30 # define __kernel 31 # define __safe 32 # define __force 33 # define __nocast 34 # define __iomem 35 # define __chk_user_ptr(x) (void)0 36 # define __chk_io_ptr(x) (void)0 37 # define __builtin_warning(x, y...) (1) 38 # define __must_hold(x) 39 # define __acquires(x) 40 # define __releases(x) 41 # define __acquire(x) (void)0 42 # define __release(x) (void)0 43 # define __cond_lock(x,c) (c) 44 # define __percpu 45 # define __rcu 46 # define __pmem 47 #endif 48 49 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */ 50 #define ___PASTE(a,b) a##b 51 #define __PASTE(a,b) ___PASTE(a,b) 52 53 #ifdef __KERNEL__ 54 55 #ifdef __GNUC__ 56 #include <linux/compiler-gcc.h> 57 #endif 58 59 #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) 60 #define notrace __attribute__((hotpatch(0,0))) 61 #else 62 #define notrace __attribute__((no_instrument_function)) 63 #endif 64 65 /* Intel compiler defines __GNUC__. So we will overwrite implementations 66 * coming from above header files here 67 */ 68 #ifdef __INTEL_COMPILER 69 # include <linux/compiler-intel.h> 70 #endif 71 72 /* Clang compiler defines __GNUC__. So we will overwrite implementations 73 * coming from above header files here 74 */ 75 #ifdef __clang__ 76 #include <linux/compiler-clang.h> 77 #endif 78 79 /* 80 * Generic compiler-dependent macros required for kernel 81 * build go below this comment. Actual compiler/compiler version 82 * specific implementations come from the above header files 83 */ 84 85 struct ftrace_branch_data { 86 const char *func; 87 const char *file; 88 unsigned line; 89 union { 90 struct { 91 unsigned long correct; 92 unsigned long incorrect; 93 }; 94 struct { 95 unsigned long miss; 96 unsigned long hit; 97 }; 98 unsigned long miss_hit[2]; 99 }; 100 }; 101 102 /* 103 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code 104 * to disable branch tracing on a per file basis. 105 */ 106 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \ 107 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) 108 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); 109 110 #define likely_notrace(x) __builtin_expect(!!(x), 1) 111 #define unlikely_notrace(x) __builtin_expect(!!(x), 0) 112 113 #define __branch_check__(x, expect) ({ \ 114 int ______r; \ 115 static struct ftrace_branch_data \ 116 __attribute__((__aligned__(4))) \ 117 __attribute__((section("_ftrace_annotated_branch"))) \ 118 ______f = { \ 119 .func = __func__, \ 120 .file = __FILE__, \ 121 .line = __LINE__, \ 122 }; \ 123 ______r = likely_notrace(x); \ 124 ftrace_likely_update(&______f, ______r, expect); \ 125 ______r; \ 126 }) 127 128 /* 129 * Using __builtin_constant_p(x) to ignore cases where the return 130 * value is always the same. This idea is taken from a similar patch 131 * written by Daniel Walker. 132 */ 133 # ifndef likely 134 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1)) 135 # endif 136 # ifndef unlikely 137 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0)) 138 # endif 139 140 #ifdef CONFIG_PROFILE_ALL_BRANCHES 141 /* 142 * "Define 'is'", Bill Clinton 143 * "Define 'if'", Steven Rostedt 144 */ 145 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) ) 146 #define __trace_if(cond) \ 147 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \ 148 ({ \ 149 int ______r; \ 150 static struct ftrace_branch_data \ 151 __attribute__((__aligned__(4))) \ 152 __attribute__((section("_ftrace_branch"))) \ 153 ______f = { \ 154 .func = __func__, \ 155 .file = __FILE__, \ 156 .line = __LINE__, \ 157 }; \ 158 ______r = !!(cond); \ 159 ______f.miss_hit[______r]++; \ 160 ______r; \ 161 })) 162 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 163 164 #else 165 # define likely(x) __builtin_expect(!!(x), 1) 166 # define unlikely(x) __builtin_expect(!!(x), 0) 167 #endif 168 169 /* Optimization barrier */ 170 #ifndef barrier 171 # define barrier() __memory_barrier() 172 #endif 173 174 #ifndef barrier_data 175 # define barrier_data(ptr) barrier() 176 #endif 177 178 /* Unreachable code */ 179 #ifndef unreachable 180 # define unreachable() do { } while (1) 181 #endif 182 183 #ifndef RELOC_HIDE 184 # define RELOC_HIDE(ptr, off) \ 185 ({ unsigned long __ptr; \ 186 __ptr = (unsigned long) (ptr); \ 187 (typeof(ptr)) (__ptr + (off)); }) 188 #endif 189 190 #ifndef OPTIMIZER_HIDE_VAR 191 #define OPTIMIZER_HIDE_VAR(var) barrier() 192 #endif 193 194 /* Not-quite-unique ID. */ 195 #ifndef __UNIQUE_ID 196 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 197 #endif 198 199 #include <linux/types.h> 200 201 #define __READ_ONCE_SIZE \ 202 ({ \ 203 switch (size) { \ 204 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ 205 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ 206 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ 207 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ 208 default: \ 209 barrier(); \ 210 __builtin_memcpy((void *)res, (const void *)p, size); \ 211 barrier(); \ 212 } \ 213 }) 214 215 static __always_inline 216 void __read_once_size(const volatile void *p, void *res, int size) 217 { 218 __READ_ONCE_SIZE; 219 } 220 221 #ifdef CONFIG_KASAN 222 /* 223 * This function is not 'inline' because __no_sanitize_address confilcts 224 * with inlining. Attempt to inline it may cause a build failure. 225 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 226 * '__maybe_unused' allows us to avoid defined-but-not-used warnings. 227 */ 228 static __no_sanitize_address __maybe_unused 229 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 230 { 231 __READ_ONCE_SIZE; 232 } 233 #else 234 static __always_inline 235 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 236 { 237 __READ_ONCE_SIZE; 238 } 239 #endif 240 241 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 242 { 243 switch (size) { 244 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 245 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 246 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 247 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 248 default: 249 barrier(); 250 __builtin_memcpy((void *)p, (const void *)res, size); 251 barrier(); 252 } 253 } 254 255 /* 256 * Prevent the compiler from merging or refetching reads or writes. The 257 * compiler is also forbidden from reordering successive instances of 258 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the 259 * compiler is aware of some particular ordering. One way to make the 260 * compiler aware of ordering is to put the two invocations of READ_ONCE, 261 * WRITE_ONCE or ACCESS_ONCE() in different C statements. 262 * 263 * In contrast to ACCESS_ONCE these two macros will also work on aggregate 264 * data types like structs or unions. If the size of the accessed data 265 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) 266 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a 267 * compile-time warning. 268 * 269 * Their two major use cases are: (1) Mediating communication between 270 * process-level code and irq/NMI handlers, all running on the same CPU, 271 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 272 * mutilate accesses that either do not require ordering or that interact 273 * with an explicit memory barrier or atomic instruction that provides the 274 * required ordering. 275 */ 276 277 #define __READ_ONCE(x, check) \ 278 ({ \ 279 union { typeof(x) __val; char __c[1]; } __u; \ 280 if (check) \ 281 __read_once_size(&(x), __u.__c, sizeof(x)); \ 282 else \ 283 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 284 __u.__val; \ 285 }) 286 #define READ_ONCE(x) __READ_ONCE(x, 1) 287 288 /* 289 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 290 * to hide memory access from KASAN. 291 */ 292 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 293 294 #define WRITE_ONCE(x, val) \ 295 ({ \ 296 union { typeof(x) __val; char __c[1]; } __u = \ 297 { .__val = (__force typeof(x)) (val) }; \ 298 __write_once_size(&(x), __u.__c, sizeof(x)); \ 299 __u.__val; \ 300 }) 301 302 /** 303 * smp_cond_acquire() - Spin wait for cond with ACQUIRE ordering 304 * @cond: boolean expression to wait for 305 * 306 * Equivalent to using smp_load_acquire() on the condition variable but employs 307 * the control dependency of the wait to reduce the barrier on many platforms. 308 * 309 * The control dependency provides a LOAD->STORE order, the additional RMB 310 * provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order, 311 * aka. ACQUIRE. 312 */ 313 #define smp_cond_acquire(cond) do { \ 314 while (!(cond)) \ 315 cpu_relax(); \ 316 smp_rmb(); /* ctrl + rmb := acquire */ \ 317 } while (0) 318 319 #endif /* __KERNEL__ */ 320 321 #endif /* __ASSEMBLY__ */ 322 323 #ifdef __KERNEL__ 324 /* 325 * Allow us to mark functions as 'deprecated' and have gcc emit a nice 326 * warning for each use, in hopes of speeding the functions removal. 327 * Usage is: 328 * int __deprecated foo(void) 329 */ 330 #ifndef __deprecated 331 # define __deprecated /* unimplemented */ 332 #endif 333 334 #ifdef MODULE 335 #define __deprecated_for_modules __deprecated 336 #else 337 #define __deprecated_for_modules 338 #endif 339 340 #ifndef __must_check 341 #define __must_check 342 #endif 343 344 #ifndef CONFIG_ENABLE_MUST_CHECK 345 #undef __must_check 346 #define __must_check 347 #endif 348 #ifndef CONFIG_ENABLE_WARN_DEPRECATED 349 #undef __deprecated 350 #undef __deprecated_for_modules 351 #define __deprecated 352 #define __deprecated_for_modules 353 #endif 354 355 /* 356 * Allow us to avoid 'defined but not used' warnings on functions and data, 357 * as well as force them to be emitted to the assembly file. 358 * 359 * As of gcc 3.4, static functions that are not marked with attribute((used)) 360 * may be elided from the assembly file. As of gcc 3.4, static data not so 361 * marked will not be elided, but this may change in a future gcc version. 362 * 363 * NOTE: Because distributions shipped with a backported unit-at-a-time 364 * compiler in gcc 3.3, we must define __used to be __attribute__((used)) 365 * for gcc >=3.3 instead of 3.4. 366 * 367 * In prior versions of gcc, such functions and data would be emitted, but 368 * would be warned about except with attribute((unused)). 369 * 370 * Mark functions that are referenced only in inline assembly as __used so 371 * the code is emitted even though it appears to be unreferenced. 372 */ 373 #ifndef __used 374 # define __used /* unimplemented */ 375 #endif 376 377 #ifndef __maybe_unused 378 # define __maybe_unused /* unimplemented */ 379 #endif 380 381 #ifndef __always_unused 382 # define __always_unused /* unimplemented */ 383 #endif 384 385 #ifndef noinline 386 #define noinline 387 #endif 388 389 /* 390 * Rather then using noinline to prevent stack consumption, use 391 * noinline_for_stack instead. For documentation reasons. 392 */ 393 #define noinline_for_stack noinline 394 395 #ifndef __always_inline 396 #define __always_inline inline 397 #endif 398 399 #endif /* __KERNEL__ */ 400 401 /* 402 * From the GCC manual: 403 * 404 * Many functions do not examine any values except their arguments, 405 * and have no effects except the return value. Basically this is 406 * just slightly more strict class than the `pure' attribute above, 407 * since function is not allowed to read global memory. 408 * 409 * Note that a function that has pointer arguments and examines the 410 * data pointed to must _not_ be declared `const'. Likewise, a 411 * function that calls a non-`const' function usually must not be 412 * `const'. It does not make sense for a `const' function to return 413 * `void'. 414 */ 415 #ifndef __attribute_const__ 416 # define __attribute_const__ /* unimplemented */ 417 #endif 418 419 /* 420 * Tell gcc if a function is cold. The compiler will assume any path 421 * directly leading to the call is unlikely. 422 */ 423 424 #ifndef __cold 425 #define __cold 426 #endif 427 428 /* Simple shorthand for a section definition */ 429 #ifndef __section 430 # define __section(S) __attribute__ ((__section__(#S))) 431 #endif 432 433 #ifndef __visible 434 #define __visible 435 #endif 436 437 /* 438 * Assume alignment of return value. 439 */ 440 #ifndef __assume_aligned 441 #define __assume_aligned(a, ...) 442 #endif 443 444 445 /* Are two types/vars the same type (ignoring qualifiers)? */ 446 #ifndef __same_type 447 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) 448 #endif 449 450 /* Is this type a native word size -- useful for atomic operations */ 451 #ifndef __native_word 452 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) 453 #endif 454 455 /* Compile time object size, -1 for unknown */ 456 #ifndef __compiletime_object_size 457 # define __compiletime_object_size(obj) -1 458 #endif 459 #ifndef __compiletime_warning 460 # define __compiletime_warning(message) 461 #endif 462 #ifndef __compiletime_error 463 # define __compiletime_error(message) 464 /* 465 * Sparse complains of variable sized arrays due to the temporary variable in 466 * __compiletime_assert. Unfortunately we can't just expand it out to make 467 * sparse see a constant array size without breaking compiletime_assert on old 468 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. 469 */ 470 # ifndef __CHECKER__ 471 # define __compiletime_error_fallback(condition) \ 472 do { ((void)sizeof(char[1 - 2 * condition])); } while (0) 473 # endif 474 #endif 475 #ifndef __compiletime_error_fallback 476 # define __compiletime_error_fallback(condition) do { } while (0) 477 #endif 478 479 #define __compiletime_assert(condition, msg, prefix, suffix) \ 480 do { \ 481 bool __cond = !(condition); \ 482 extern void prefix ## suffix(void) __compiletime_error(msg); \ 483 if (__cond) \ 484 prefix ## suffix(); \ 485 __compiletime_error_fallback(__cond); \ 486 } while (0) 487 488 #define _compiletime_assert(condition, msg, prefix, suffix) \ 489 __compiletime_assert(condition, msg, prefix, suffix) 490 491 /** 492 * compiletime_assert - break build and emit msg if condition is false 493 * @condition: a compile-time constant condition to check 494 * @msg: a message to emit if condition is false 495 * 496 * In tradition of POSIX assert, this macro will break the build if the 497 * supplied condition is *false*, emitting the supplied error message if the 498 * compiler has support to do so. 499 */ 500 #define compiletime_assert(condition, msg) \ 501 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 502 503 #define compiletime_assert_atomic_type(t) \ 504 compiletime_assert(__native_word(t), \ 505 "Need native word sized stores/loads for atomicity.") 506 507 /* 508 * Prevent the compiler from merging or refetching accesses. The compiler 509 * is also forbidden from reordering successive instances of ACCESS_ONCE(), 510 * but only when the compiler is aware of some particular ordering. One way 511 * to make the compiler aware of ordering is to put the two invocations of 512 * ACCESS_ONCE() in different C statements. 513 * 514 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE 515 * on a union member will work as long as the size of the member matches the 516 * size of the union and the size is smaller than word size. 517 * 518 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication 519 * between process-level code and irq/NMI handlers, all running on the same CPU, 520 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 521 * mutilate accesses that either do not require ordering or that interact 522 * with an explicit memory barrier or atomic instruction that provides the 523 * required ordering. 524 * 525 * If possible use READ_ONCE()/WRITE_ONCE() instead. 526 */ 527 #define __ACCESS_ONCE(x) ({ \ 528 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \ 529 (volatile typeof(x) *)&(x); }) 530 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) 531 532 /** 533 * lockless_dereference() - safely load a pointer for later dereference 534 * @p: The pointer to load 535 * 536 * Similar to rcu_dereference(), but for situations where the pointed-to 537 * object's lifetime is managed by something other than RCU. That 538 * "something other" might be reference counting or simple immortality. 539 */ 540 #define lockless_dereference(p) \ 541 ({ \ 542 typeof(p) _________p1 = READ_ONCE(p); \ 543 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ 544 (_________p1); \ 545 }) 546 547 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */ 548 #ifdef CONFIG_KPROBES 549 # define __kprobes __attribute__((__section__(".kprobes.text"))) 550 # define nokprobe_inline __always_inline 551 #else 552 # define __kprobes 553 # define nokprobe_inline inline 554 #endif 555 #endif /* __LINUX_COMPILER_H */ 556