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 /* CONFIG_SPARSE_RCU_POINTER */ 24 # define __rcu 25 #endif /* CONFIG_SPARSE_RCU_POINTER */ 26 # define __private __attribute__((noderef)) 27 extern void __chk_user_ptr(const volatile void __user *); 28 extern void __chk_io_ptr(const volatile void __iomem *); 29 # define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member)) 30 #else /* __CHECKER__ */ 31 # define __user 32 # define __kernel 33 # define __safe 34 # define __force 35 # define __nocast 36 # define __iomem 37 # define __chk_user_ptr(x) (void)0 38 # define __chk_io_ptr(x) (void)0 39 # define __builtin_warning(x, y...) (1) 40 # define __must_hold(x) 41 # define __acquires(x) 42 # define __releases(x) 43 # define __acquire(x) (void)0 44 # define __release(x) (void)0 45 # define __cond_lock(x,c) (c) 46 # define __percpu 47 # define __rcu 48 # define __pmem 49 # define __private 50 # define ACCESS_PRIVATE(p, member) ((p)->member) 51 #endif /* __CHECKER__ */ 52 53 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */ 54 #define ___PASTE(a,b) a##b 55 #define __PASTE(a,b) ___PASTE(a,b) 56 57 #ifdef __KERNEL__ 58 59 #ifdef __GNUC__ 60 #include <linux/compiler-gcc.h> 61 #endif 62 63 #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) 64 #define notrace __attribute__((hotpatch(0,0))) 65 #else 66 #define notrace __attribute__((no_instrument_function)) 67 #endif 68 69 /* Intel compiler defines __GNUC__. So we will overwrite implementations 70 * coming from above header files here 71 */ 72 #ifdef __INTEL_COMPILER 73 # include <linux/compiler-intel.h> 74 #endif 75 76 /* Clang compiler defines __GNUC__. So we will overwrite implementations 77 * coming from above header files here 78 */ 79 #ifdef __clang__ 80 #include <linux/compiler-clang.h> 81 #endif 82 83 /* 84 * Generic compiler-dependent macros required for kernel 85 * build go below this comment. Actual compiler/compiler version 86 * specific implementations come from the above header files 87 */ 88 89 struct ftrace_branch_data { 90 const char *func; 91 const char *file; 92 unsigned line; 93 union { 94 struct { 95 unsigned long correct; 96 unsigned long incorrect; 97 }; 98 struct { 99 unsigned long miss; 100 unsigned long hit; 101 }; 102 unsigned long miss_hit[2]; 103 }; 104 }; 105 106 /* 107 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code 108 * to disable branch tracing on a per file basis. 109 */ 110 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \ 111 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) 112 void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); 113 114 #define likely_notrace(x) __builtin_expect(!!(x), 1) 115 #define unlikely_notrace(x) __builtin_expect(!!(x), 0) 116 117 #define __branch_check__(x, expect) ({ \ 118 int ______r; \ 119 static struct ftrace_branch_data \ 120 __attribute__((__aligned__(4))) \ 121 __attribute__((section("_ftrace_annotated_branch"))) \ 122 ______f = { \ 123 .func = __func__, \ 124 .file = __FILE__, \ 125 .line = __LINE__, \ 126 }; \ 127 ______r = likely_notrace(x); \ 128 ftrace_likely_update(&______f, ______r, expect); \ 129 ______r; \ 130 }) 131 132 /* 133 * Using __builtin_constant_p(x) to ignore cases where the return 134 * value is always the same. This idea is taken from a similar patch 135 * written by Daniel Walker. 136 */ 137 # ifndef likely 138 # define likely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1)) 139 # endif 140 # ifndef unlikely 141 # define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0)) 142 # endif 143 144 #ifdef CONFIG_PROFILE_ALL_BRANCHES 145 /* 146 * "Define 'is'", Bill Clinton 147 * "Define 'if'", Steven Rostedt 148 */ 149 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) ) 150 #define __trace_if(cond) \ 151 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \ 152 ({ \ 153 int ______r; \ 154 static struct ftrace_branch_data \ 155 __attribute__((__aligned__(4))) \ 156 __attribute__((section("_ftrace_branch"))) \ 157 ______f = { \ 158 .func = __func__, \ 159 .file = __FILE__, \ 160 .line = __LINE__, \ 161 }; \ 162 ______r = !!(cond); \ 163 ______f.miss_hit[______r]++; \ 164 ______r; \ 165 })) 166 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 167 168 #else 169 # define likely(x) __builtin_expect(!!(x), 1) 170 # define unlikely(x) __builtin_expect(!!(x), 0) 171 #endif 172 173 /* Optimization barrier */ 174 #ifndef barrier 175 # define barrier() __memory_barrier() 176 #endif 177 178 #ifndef barrier_data 179 # define barrier_data(ptr) barrier() 180 #endif 181 182 /* Unreachable code */ 183 #ifndef unreachable 184 # define unreachable() do { } while (1) 185 #endif 186 187 #ifndef RELOC_HIDE 188 # define RELOC_HIDE(ptr, off) \ 189 ({ unsigned long __ptr; \ 190 __ptr = (unsigned long) (ptr); \ 191 (typeof(ptr)) (__ptr + (off)); }) 192 #endif 193 194 #ifndef OPTIMIZER_HIDE_VAR 195 #define OPTIMIZER_HIDE_VAR(var) barrier() 196 #endif 197 198 /* Not-quite-unique ID. */ 199 #ifndef __UNIQUE_ID 200 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 201 #endif 202 203 #include <uapi/linux/types.h> 204 205 #define __READ_ONCE_SIZE \ 206 ({ \ 207 switch (size) { \ 208 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ 209 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ 210 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ 211 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ 212 default: \ 213 barrier(); \ 214 __builtin_memcpy((void *)res, (const void *)p, size); \ 215 barrier(); \ 216 } \ 217 }) 218 219 static __always_inline 220 void __read_once_size(const volatile void *p, void *res, int size) 221 { 222 __READ_ONCE_SIZE; 223 } 224 225 #ifdef CONFIG_KASAN 226 /* 227 * This function is not 'inline' because __no_sanitize_address confilcts 228 * with inlining. Attempt to inline it may cause a build failure. 229 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 230 * '__maybe_unused' allows us to avoid defined-but-not-used warnings. 231 */ 232 static __no_sanitize_address __maybe_unused 233 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 234 { 235 __READ_ONCE_SIZE; 236 } 237 #else 238 static __always_inline 239 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 240 { 241 __READ_ONCE_SIZE; 242 } 243 #endif 244 245 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 246 { 247 switch (size) { 248 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 249 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 250 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 251 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 252 default: 253 barrier(); 254 __builtin_memcpy((void *)p, (const void *)res, size); 255 barrier(); 256 } 257 } 258 259 /* 260 * Prevent the compiler from merging or refetching reads or writes. The 261 * compiler is also forbidden from reordering successive instances of 262 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the 263 * compiler is aware of some particular ordering. One way to make the 264 * compiler aware of ordering is to put the two invocations of READ_ONCE, 265 * WRITE_ONCE or ACCESS_ONCE() in different C statements. 266 * 267 * In contrast to ACCESS_ONCE these two macros will also work on aggregate 268 * data types like structs or unions. If the size of the accessed data 269 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) 270 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at 271 * least two memcpy()s: one for the __builtin_memcpy() and then one for 272 * the macro doing the copy of variable - '__u' allocated on the stack. 273 * 274 * Their two major use cases are: (1) Mediating communication between 275 * process-level code and irq/NMI handlers, all running on the same CPU, 276 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 277 * mutilate accesses that either do not require ordering or that interact 278 * with an explicit memory barrier or atomic instruction that provides the 279 * required ordering. 280 */ 281 282 #define __READ_ONCE(x, check) \ 283 ({ \ 284 union { typeof(x) __val; char __c[1]; } __u; \ 285 if (check) \ 286 __read_once_size(&(x), __u.__c, sizeof(x)); \ 287 else \ 288 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 289 __u.__val; \ 290 }) 291 #define READ_ONCE(x) __READ_ONCE(x, 1) 292 293 /* 294 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 295 * to hide memory access from KASAN. 296 */ 297 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 298 299 #define WRITE_ONCE(x, val) \ 300 ({ \ 301 union { typeof(x) __val; char __c[1]; } __u = \ 302 { .__val = (__force typeof(x)) (val) }; \ 303 __write_once_size(&(x), __u.__c, sizeof(x)); \ 304 __u.__val; \ 305 }) 306 307 /** 308 * smp_cond_acquire() - Spin wait for cond with ACQUIRE ordering 309 * @cond: boolean expression to wait for 310 * 311 * Equivalent to using smp_load_acquire() on the condition variable but employs 312 * the control dependency of the wait to reduce the barrier on many platforms. 313 * 314 * The control dependency provides a LOAD->STORE order, the additional RMB 315 * provides LOAD->LOAD order, together they provide LOAD->{LOAD,STORE} order, 316 * aka. ACQUIRE. 317 */ 318 #define smp_cond_acquire(cond) do { \ 319 while (!(cond)) \ 320 cpu_relax(); \ 321 smp_rmb(); /* ctrl + rmb := acquire */ \ 322 } while (0) 323 324 #endif /* __KERNEL__ */ 325 326 #endif /* __ASSEMBLY__ */ 327 328 #ifdef __KERNEL__ 329 /* 330 * Allow us to mark functions as 'deprecated' and have gcc emit a nice 331 * warning for each use, in hopes of speeding the functions removal. 332 * Usage is: 333 * int __deprecated foo(void) 334 */ 335 #ifndef __deprecated 336 # define __deprecated /* unimplemented */ 337 #endif 338 339 #ifdef MODULE 340 #define __deprecated_for_modules __deprecated 341 #else 342 #define __deprecated_for_modules 343 #endif 344 345 #ifndef __must_check 346 #define __must_check 347 #endif 348 349 #ifndef CONFIG_ENABLE_MUST_CHECK 350 #undef __must_check 351 #define __must_check 352 #endif 353 #ifndef CONFIG_ENABLE_WARN_DEPRECATED 354 #undef __deprecated 355 #undef __deprecated_for_modules 356 #define __deprecated 357 #define __deprecated_for_modules 358 #endif 359 360 #ifndef __malloc 361 #define __malloc 362 #endif 363 364 /* 365 * Allow us to avoid 'defined but not used' warnings on functions and data, 366 * as well as force them to be emitted to the assembly file. 367 * 368 * As of gcc 3.4, static functions that are not marked with attribute((used)) 369 * may be elided from the assembly file. As of gcc 3.4, static data not so 370 * marked will not be elided, but this may change in a future gcc version. 371 * 372 * NOTE: Because distributions shipped with a backported unit-at-a-time 373 * compiler in gcc 3.3, we must define __used to be __attribute__((used)) 374 * for gcc >=3.3 instead of 3.4. 375 * 376 * In prior versions of gcc, such functions and data would be emitted, but 377 * would be warned about except with attribute((unused)). 378 * 379 * Mark functions that are referenced only in inline assembly as __used so 380 * the code is emitted even though it appears to be unreferenced. 381 */ 382 #ifndef __used 383 # define __used /* unimplemented */ 384 #endif 385 386 #ifndef __maybe_unused 387 # define __maybe_unused /* unimplemented */ 388 #endif 389 390 #ifndef __always_unused 391 # define __always_unused /* unimplemented */ 392 #endif 393 394 #ifndef noinline 395 #define noinline 396 #endif 397 398 /* 399 * Rather then using noinline to prevent stack consumption, use 400 * noinline_for_stack instead. For documentation reasons. 401 */ 402 #define noinline_for_stack noinline 403 404 #ifndef __always_inline 405 #define __always_inline inline 406 #endif 407 408 #endif /* __KERNEL__ */ 409 410 /* 411 * From the GCC manual: 412 * 413 * Many functions do not examine any values except their arguments, 414 * and have no effects except the return value. Basically this is 415 * just slightly more strict class than the `pure' attribute above, 416 * since function is not allowed to read global memory. 417 * 418 * Note that a function that has pointer arguments and examines the 419 * data pointed to must _not_ be declared `const'. Likewise, a 420 * function that calls a non-`const' function usually must not be 421 * `const'. It does not make sense for a `const' function to return 422 * `void'. 423 */ 424 #ifndef __attribute_const__ 425 # define __attribute_const__ /* unimplemented */ 426 #endif 427 428 /* 429 * Tell gcc if a function is cold. The compiler will assume any path 430 * directly leading to the call is unlikely. 431 */ 432 433 #ifndef __cold 434 #define __cold 435 #endif 436 437 /* Simple shorthand for a section definition */ 438 #ifndef __section 439 # define __section(S) __attribute__ ((__section__(#S))) 440 #endif 441 442 #ifndef __visible 443 #define __visible 444 #endif 445 446 /* 447 * Assume alignment of return value. 448 */ 449 #ifndef __assume_aligned 450 #define __assume_aligned(a, ...) 451 #endif 452 453 454 /* Are two types/vars the same type (ignoring qualifiers)? */ 455 #ifndef __same_type 456 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) 457 #endif 458 459 /* Is this type a native word size -- useful for atomic operations */ 460 #ifndef __native_word 461 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) 462 #endif 463 464 /* Compile time object size, -1 for unknown */ 465 #ifndef __compiletime_object_size 466 # define __compiletime_object_size(obj) -1 467 #endif 468 #ifndef __compiletime_warning 469 # define __compiletime_warning(message) 470 #endif 471 #ifndef __compiletime_error 472 # define __compiletime_error(message) 473 /* 474 * Sparse complains of variable sized arrays due to the temporary variable in 475 * __compiletime_assert. Unfortunately we can't just expand it out to make 476 * sparse see a constant array size without breaking compiletime_assert on old 477 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. 478 */ 479 # ifndef __CHECKER__ 480 # define __compiletime_error_fallback(condition) \ 481 do { ((void)sizeof(char[1 - 2 * condition])); } while (0) 482 # endif 483 #endif 484 #ifndef __compiletime_error_fallback 485 # define __compiletime_error_fallback(condition) do { } while (0) 486 #endif 487 488 #define __compiletime_assert(condition, msg, prefix, suffix) \ 489 do { \ 490 bool __cond = !(condition); \ 491 extern void prefix ## suffix(void) __compiletime_error(msg); \ 492 if (__cond) \ 493 prefix ## suffix(); \ 494 __compiletime_error_fallback(__cond); \ 495 } while (0) 496 497 #define _compiletime_assert(condition, msg, prefix, suffix) \ 498 __compiletime_assert(condition, msg, prefix, suffix) 499 500 /** 501 * compiletime_assert - break build and emit msg if condition is false 502 * @condition: a compile-time constant condition to check 503 * @msg: a message to emit if condition is false 504 * 505 * In tradition of POSIX assert, this macro will break the build if the 506 * supplied condition is *false*, emitting the supplied error message if the 507 * compiler has support to do so. 508 */ 509 #define compiletime_assert(condition, msg) \ 510 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 511 512 #define compiletime_assert_atomic_type(t) \ 513 compiletime_assert(__native_word(t), \ 514 "Need native word sized stores/loads for atomicity.") 515 516 /* 517 * Prevent the compiler from merging or refetching accesses. The compiler 518 * is also forbidden from reordering successive instances of ACCESS_ONCE(), 519 * but only when the compiler is aware of some particular ordering. One way 520 * to make the compiler aware of ordering is to put the two invocations of 521 * ACCESS_ONCE() in different C statements. 522 * 523 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE 524 * on a union member will work as long as the size of the member matches the 525 * size of the union and the size is smaller than word size. 526 * 527 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication 528 * between process-level code and irq/NMI handlers, all running on the same CPU, 529 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 530 * mutilate accesses that either do not require ordering or that interact 531 * with an explicit memory barrier or atomic instruction that provides the 532 * required ordering. 533 * 534 * If possible use READ_ONCE()/WRITE_ONCE() instead. 535 */ 536 #define __ACCESS_ONCE(x) ({ \ 537 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \ 538 (volatile typeof(x) *)&(x); }) 539 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) 540 541 /** 542 * lockless_dereference() - safely load a pointer for later dereference 543 * @p: The pointer to load 544 * 545 * Similar to rcu_dereference(), but for situations where the pointed-to 546 * object's lifetime is managed by something other than RCU. That 547 * "something other" might be reference counting or simple immortality. 548 */ 549 #define lockless_dereference(p) \ 550 ({ \ 551 typeof(p) _________p1 = READ_ONCE(p); \ 552 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ 553 (_________p1); \ 554 }) 555 556 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */ 557 #ifdef CONFIG_KPROBES 558 # define __kprobes __attribute__((__section__(".kprobes.text"))) 559 # define nokprobe_inline __always_inline 560 #else 561 # define __kprobes 562 # define nokprobe_inline inline 563 #endif 564 #endif /* __LINUX_COMPILER_H */ 565