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 __rcu __attribute__((noderef, address_space(4))) 21 # define __private __attribute__((noderef)) 22 extern void __chk_user_ptr(const volatile void __user *); 23 extern void __chk_io_ptr(const volatile void __iomem *); 24 # define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member)) 25 #else /* __CHECKER__ */ 26 # ifdef STRUCTLEAK_PLUGIN 27 # define __user __attribute__((user)) 28 # else 29 # define __user 30 # endif 31 # define __kernel 32 # define __safe 33 # define __force 34 # define __nocast 35 # define __iomem 36 # define __chk_user_ptr(x) (void)0 37 # define __chk_io_ptr(x) (void)0 38 # define __builtin_warning(x, y...) (1) 39 # define __must_hold(x) 40 # define __acquires(x) 41 # define __releases(x) 42 # define __acquire(x) (void)0 43 # define __release(x) (void)0 44 # define __cond_lock(x,c) (c) 45 # define __percpu 46 # define __rcu 47 # define __private 48 # define ACCESS_PRIVATE(p, member) ((p)->member) 49 #endif /* __CHECKER__ */ 50 51 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */ 52 #define ___PASTE(a,b) a##b 53 #define __PASTE(a,b) ___PASTE(a,b) 54 55 #ifdef __KERNEL__ 56 57 #ifdef __GNUC__ 58 #include <linux/compiler-gcc.h> 59 #endif 60 61 #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) 62 #define notrace __attribute__((hotpatch(0,0))) 63 #else 64 #define notrace __attribute__((no_instrument_function)) 65 #endif 66 67 /* Intel compiler defines __GNUC__. So we will overwrite implementations 68 * coming from above header files here 69 */ 70 #ifdef __INTEL_COMPILER 71 # include <linux/compiler-intel.h> 72 #endif 73 74 /* Clang compiler defines __GNUC__. So we will overwrite implementations 75 * coming from above header files here 76 */ 77 #ifdef __clang__ 78 #include <linux/compiler-clang.h> 79 #endif 80 81 /* 82 * Generic compiler-dependent macros required for kernel 83 * build go below this comment. Actual compiler/compiler version 84 * specific implementations come from the above header files 85 */ 86 87 struct ftrace_branch_data { 88 const char *func; 89 const char *file; 90 unsigned line; 91 union { 92 struct { 93 unsigned long correct; 94 unsigned long incorrect; 95 }; 96 struct { 97 unsigned long miss; 98 unsigned long hit; 99 }; 100 unsigned long miss_hit[2]; 101 }; 102 }; 103 104 struct ftrace_likely_data { 105 struct ftrace_branch_data data; 106 unsigned long constant; 107 }; 108 109 /* 110 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code 111 * to disable branch tracing on a per file basis. 112 */ 113 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \ 114 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) 115 void ftrace_likely_update(struct ftrace_likely_data *f, int val, 116 int expect, int is_constant); 117 118 #define likely_notrace(x) __builtin_expect(!!(x), 1) 119 #define unlikely_notrace(x) __builtin_expect(!!(x), 0) 120 121 #define __branch_check__(x, expect, is_constant) ({ \ 122 int ______r; \ 123 static struct ftrace_likely_data \ 124 __attribute__((__aligned__(4))) \ 125 __attribute__((section("_ftrace_annotated_branch"))) \ 126 ______f = { \ 127 .data.func = __func__, \ 128 .data.file = __FILE__, \ 129 .data.line = __LINE__, \ 130 }; \ 131 ______r = __builtin_expect(!!(x), expect); \ 132 ftrace_likely_update(&______f, ______r, \ 133 expect, is_constant); \ 134 ______r; \ 135 }) 136 137 /* 138 * Using __builtin_constant_p(x) to ignore cases where the return 139 * value is always the same. This idea is taken from a similar patch 140 * written by Daniel Walker. 141 */ 142 # ifndef likely 143 # define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x))) 144 # endif 145 # ifndef unlikely 146 # define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x))) 147 # endif 148 149 #ifdef CONFIG_PROFILE_ALL_BRANCHES 150 /* 151 * "Define 'is'", Bill Clinton 152 * "Define 'if'", Steven Rostedt 153 */ 154 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) ) 155 #define __trace_if(cond) \ 156 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \ 157 ({ \ 158 int ______r; \ 159 static struct ftrace_branch_data \ 160 __attribute__((__aligned__(4))) \ 161 __attribute__((section("_ftrace_branch"))) \ 162 ______f = { \ 163 .func = __func__, \ 164 .file = __FILE__, \ 165 .line = __LINE__, \ 166 }; \ 167 ______r = !!(cond); \ 168 ______f.miss_hit[______r]++; \ 169 ______r; \ 170 })) 171 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 172 173 #else 174 # define likely(x) __builtin_expect(!!(x), 1) 175 # define unlikely(x) __builtin_expect(!!(x), 0) 176 #endif 177 178 /* Optimization barrier */ 179 #ifndef barrier 180 # define barrier() __memory_barrier() 181 #endif 182 183 #ifndef barrier_data 184 # define barrier_data(ptr) barrier() 185 #endif 186 187 /* Unreachable code */ 188 #ifndef unreachable 189 # define unreachable() do { } while (1) 190 #endif 191 192 /* 193 * KENTRY - kernel entry point 194 * This can be used to annotate symbols (functions or data) that are used 195 * without their linker symbol being referenced explicitly. For example, 196 * interrupt vector handlers, or functions in the kernel image that are found 197 * programatically. 198 * 199 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those 200 * are handled in their own way (with KEEP() in linker scripts). 201 * 202 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the 203 * linker script. For example an architecture could KEEP() its entire 204 * boot/exception vector code rather than annotate each function and data. 205 */ 206 #ifndef KENTRY 207 # define KENTRY(sym) \ 208 extern typeof(sym) sym; \ 209 static const unsigned long __kentry_##sym \ 210 __used \ 211 __attribute__((section("___kentry" "+" #sym ), used)) \ 212 = (unsigned long)&sym; 213 #endif 214 215 #ifndef RELOC_HIDE 216 # define RELOC_HIDE(ptr, off) \ 217 ({ unsigned long __ptr; \ 218 __ptr = (unsigned long) (ptr); \ 219 (typeof(ptr)) (__ptr + (off)); }) 220 #endif 221 222 #ifndef OPTIMIZER_HIDE_VAR 223 #define OPTIMIZER_HIDE_VAR(var) barrier() 224 #endif 225 226 /* Not-quite-unique ID. */ 227 #ifndef __UNIQUE_ID 228 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 229 #endif 230 231 #include <uapi/linux/types.h> 232 233 #define __READ_ONCE_SIZE \ 234 ({ \ 235 switch (size) { \ 236 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ 237 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ 238 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ 239 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ 240 default: \ 241 barrier(); \ 242 __builtin_memcpy((void *)res, (const void *)p, size); \ 243 barrier(); \ 244 } \ 245 }) 246 247 static __always_inline 248 void __read_once_size(const volatile void *p, void *res, int size) 249 { 250 __READ_ONCE_SIZE; 251 } 252 253 #ifdef CONFIG_KASAN 254 /* 255 * This function is not 'inline' because __no_sanitize_address confilcts 256 * with inlining. Attempt to inline it may cause a build failure. 257 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 258 * '__maybe_unused' allows us to avoid defined-but-not-used warnings. 259 */ 260 static __no_sanitize_address __maybe_unused 261 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 262 { 263 __READ_ONCE_SIZE; 264 } 265 #else 266 static __always_inline 267 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 268 { 269 __READ_ONCE_SIZE; 270 } 271 #endif 272 273 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 274 { 275 switch (size) { 276 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 277 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 278 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 279 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 280 default: 281 barrier(); 282 __builtin_memcpy((void *)p, (const void *)res, size); 283 barrier(); 284 } 285 } 286 287 /* 288 * Prevent the compiler from merging or refetching reads or writes. The 289 * compiler is also forbidden from reordering successive instances of 290 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the 291 * compiler is aware of some particular ordering. One way to make the 292 * compiler aware of ordering is to put the two invocations of READ_ONCE, 293 * WRITE_ONCE or ACCESS_ONCE() in different C statements. 294 * 295 * In contrast to ACCESS_ONCE these two macros will also work on aggregate 296 * data types like structs or unions. If the size of the accessed data 297 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) 298 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at 299 * least two memcpy()s: one for the __builtin_memcpy() and then one for 300 * the macro doing the copy of variable - '__u' allocated on the stack. 301 * 302 * Their two major use cases are: (1) Mediating communication between 303 * process-level code and irq/NMI handlers, all running on the same CPU, 304 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 305 * mutilate accesses that either do not require ordering or that interact 306 * with an explicit memory barrier or atomic instruction that provides the 307 * required ordering. 308 */ 309 310 #define __READ_ONCE(x, check) \ 311 ({ \ 312 union { typeof(x) __val; char __c[1]; } __u; \ 313 if (check) \ 314 __read_once_size(&(x), __u.__c, sizeof(x)); \ 315 else \ 316 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 317 __u.__val; \ 318 }) 319 #define READ_ONCE(x) __READ_ONCE(x, 1) 320 321 /* 322 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 323 * to hide memory access from KASAN. 324 */ 325 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 326 327 #define WRITE_ONCE(x, val) \ 328 ({ \ 329 union { typeof(x) __val; char __c[1]; } __u = \ 330 { .__val = (__force typeof(x)) (val) }; \ 331 __write_once_size(&(x), __u.__c, sizeof(x)); \ 332 __u.__val; \ 333 }) 334 335 #endif /* __KERNEL__ */ 336 337 #endif /* __ASSEMBLY__ */ 338 339 #ifdef __KERNEL__ 340 /* 341 * Allow us to mark functions as 'deprecated' and have gcc emit a nice 342 * warning for each use, in hopes of speeding the functions removal. 343 * Usage is: 344 * int __deprecated foo(void) 345 */ 346 #ifndef __deprecated 347 # define __deprecated /* unimplemented */ 348 #endif 349 350 #ifdef MODULE 351 #define __deprecated_for_modules __deprecated 352 #else 353 #define __deprecated_for_modules 354 #endif 355 356 #ifndef __must_check 357 #define __must_check 358 #endif 359 360 #ifndef CONFIG_ENABLE_MUST_CHECK 361 #undef __must_check 362 #define __must_check 363 #endif 364 #ifndef CONFIG_ENABLE_WARN_DEPRECATED 365 #undef __deprecated 366 #undef __deprecated_for_modules 367 #define __deprecated 368 #define __deprecated_for_modules 369 #endif 370 371 #ifndef __malloc 372 #define __malloc 373 #endif 374 375 /* 376 * Allow us to avoid 'defined but not used' warnings on functions and data, 377 * as well as force them to be emitted to the assembly file. 378 * 379 * As of gcc 3.4, static functions that are not marked with attribute((used)) 380 * may be elided from the assembly file. As of gcc 3.4, static data not so 381 * marked will not be elided, but this may change in a future gcc version. 382 * 383 * NOTE: Because distributions shipped with a backported unit-at-a-time 384 * compiler in gcc 3.3, we must define __used to be __attribute__((used)) 385 * for gcc >=3.3 instead of 3.4. 386 * 387 * In prior versions of gcc, such functions and data would be emitted, but 388 * would be warned about except with attribute((unused)). 389 * 390 * Mark functions that are referenced only in inline assembly as __used so 391 * the code is emitted even though it appears to be unreferenced. 392 */ 393 #ifndef __used 394 # define __used /* unimplemented */ 395 #endif 396 397 #ifndef __maybe_unused 398 # define __maybe_unused /* unimplemented */ 399 #endif 400 401 #ifndef __always_unused 402 # define __always_unused /* unimplemented */ 403 #endif 404 405 #ifndef noinline 406 #define noinline 407 #endif 408 409 /* 410 * Rather then using noinline to prevent stack consumption, use 411 * noinline_for_stack instead. For documentation reasons. 412 */ 413 #define noinline_for_stack noinline 414 415 #ifndef __always_inline 416 #define __always_inline inline 417 #endif 418 419 #endif /* __KERNEL__ */ 420 421 /* 422 * From the GCC manual: 423 * 424 * Many functions do not examine any values except their arguments, 425 * and have no effects except the return value. Basically this is 426 * just slightly more strict class than the `pure' attribute above, 427 * since function is not allowed to read global memory. 428 * 429 * Note that a function that has pointer arguments and examines the 430 * data pointed to must _not_ be declared `const'. Likewise, a 431 * function that calls a non-`const' function usually must not be 432 * `const'. It does not make sense for a `const' function to return 433 * `void'. 434 */ 435 #ifndef __attribute_const__ 436 # define __attribute_const__ /* unimplemented */ 437 #endif 438 439 #ifndef __designated_init 440 # define __designated_init 441 #endif 442 443 #ifndef __latent_entropy 444 # define __latent_entropy 445 #endif 446 447 #ifndef __randomize_layout 448 # define __randomize_layout __designated_init 449 #endif 450 451 #ifndef __no_randomize_layout 452 # define __no_randomize_layout 453 #endif 454 455 #ifndef randomized_struct_fields_start 456 # define randomized_struct_fields_start 457 # define randomized_struct_fields_end 458 #endif 459 460 /* 461 * Tell gcc if a function is cold. The compiler will assume any path 462 * directly leading to the call is unlikely. 463 */ 464 465 #ifndef __cold 466 #define __cold 467 #endif 468 469 /* Simple shorthand for a section definition */ 470 #ifndef __section 471 # define __section(S) __attribute__ ((__section__(#S))) 472 #endif 473 474 #ifndef __visible 475 #define __visible 476 #endif 477 478 /* 479 * Assume alignment of return value. 480 */ 481 #ifndef __assume_aligned 482 #define __assume_aligned(a, ...) 483 #endif 484 485 486 /* Are two types/vars the same type (ignoring qualifiers)? */ 487 #ifndef __same_type 488 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) 489 #endif 490 491 /* Is this type a native word size -- useful for atomic operations */ 492 #ifndef __native_word 493 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) 494 #endif 495 496 /* Compile time object size, -1 for unknown */ 497 #ifndef __compiletime_object_size 498 # define __compiletime_object_size(obj) -1 499 #endif 500 #ifndef __compiletime_warning 501 # define __compiletime_warning(message) 502 #endif 503 #ifndef __compiletime_error 504 # define __compiletime_error(message) 505 /* 506 * Sparse complains of variable sized arrays due to the temporary variable in 507 * __compiletime_assert. Unfortunately we can't just expand it out to make 508 * sparse see a constant array size without breaking compiletime_assert on old 509 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. 510 */ 511 # ifndef __CHECKER__ 512 # define __compiletime_error_fallback(condition) \ 513 do { ((void)sizeof(char[1 - 2 * condition])); } while (0) 514 # endif 515 #endif 516 #ifndef __compiletime_error_fallback 517 # define __compiletime_error_fallback(condition) do { } while (0) 518 #endif 519 520 #define __compiletime_assert(condition, msg, prefix, suffix) \ 521 do { \ 522 bool __cond = !(condition); \ 523 extern void prefix ## suffix(void) __compiletime_error(msg); \ 524 if (__cond) \ 525 prefix ## suffix(); \ 526 __compiletime_error_fallback(__cond); \ 527 } while (0) 528 529 #define _compiletime_assert(condition, msg, prefix, suffix) \ 530 __compiletime_assert(condition, msg, prefix, suffix) 531 532 /** 533 * compiletime_assert - break build and emit msg if condition is false 534 * @condition: a compile-time constant condition to check 535 * @msg: a message to emit if condition is false 536 * 537 * In tradition of POSIX assert, this macro will break the build if the 538 * supplied condition is *false*, emitting the supplied error message if the 539 * compiler has support to do so. 540 */ 541 #define compiletime_assert(condition, msg) \ 542 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 543 544 #define compiletime_assert_atomic_type(t) \ 545 compiletime_assert(__native_word(t), \ 546 "Need native word sized stores/loads for atomicity.") 547 548 /* 549 * Prevent the compiler from merging or refetching accesses. The compiler 550 * is also forbidden from reordering successive instances of ACCESS_ONCE(), 551 * but only when the compiler is aware of some particular ordering. One way 552 * to make the compiler aware of ordering is to put the two invocations of 553 * ACCESS_ONCE() in different C statements. 554 * 555 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE 556 * on a union member will work as long as the size of the member matches the 557 * size of the union and the size is smaller than word size. 558 * 559 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication 560 * between process-level code and irq/NMI handlers, all running on the same CPU, 561 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 562 * mutilate accesses that either do not require ordering or that interact 563 * with an explicit memory barrier or atomic instruction that provides the 564 * required ordering. 565 * 566 * If possible use READ_ONCE()/WRITE_ONCE() instead. 567 */ 568 #define __ACCESS_ONCE(x) ({ \ 569 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \ 570 (volatile typeof(x) *)&(x); }) 571 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) 572 573 /** 574 * lockless_dereference() - safely load a pointer for later dereference 575 * @p: The pointer to load 576 * 577 * Similar to rcu_dereference(), but for situations where the pointed-to 578 * object's lifetime is managed by something other than RCU. That 579 * "something other" might be reference counting or simple immortality. 580 * 581 * The seemingly unused variable ___typecheck_p validates that @p is 582 * indeed a pointer type by using a pointer to typeof(*p) as the type. 583 * Taking a pointer to typeof(*p) again is needed in case p is void *. 584 */ 585 #define lockless_dereference(p) \ 586 ({ \ 587 typeof(p) _________p1 = READ_ONCE(p); \ 588 typeof(*(p)) *___typecheck_p __maybe_unused; \ 589 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ 590 (_________p1); \ 591 }) 592 593 #endif /* __LINUX_COMPILER_H */ 594