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 #ifdef CONFIG_STACK_VALIDATION 189 #define annotate_reachable() ({ \ 190 asm("%c0:\n\t" \ 191 ".pushsection .discard.reachable\n\t" \ 192 ".long %c0b - .\n\t" \ 193 ".popsection\n\t" : : "i" (__LINE__)); \ 194 }) 195 #define annotate_unreachable() ({ \ 196 asm("%c0:\n\t" \ 197 ".pushsection .discard.unreachable\n\t" \ 198 ".long %c0b - .\n\t" \ 199 ".popsection\n\t" : : "i" (__LINE__)); \ 200 }) 201 #define ASM_UNREACHABLE \ 202 "999:\n\t" \ 203 ".pushsection .discard.unreachable\n\t" \ 204 ".long 999b - .\n\t" \ 205 ".popsection\n\t" 206 #else 207 #define annotate_reachable() 208 #define annotate_unreachable() 209 #endif 210 211 #ifndef ASM_UNREACHABLE 212 # define ASM_UNREACHABLE 213 #endif 214 #ifndef unreachable 215 # define unreachable() do { annotate_reachable(); do { } while (1); } while (0) 216 #endif 217 218 /* 219 * KENTRY - kernel entry point 220 * This can be used to annotate symbols (functions or data) that are used 221 * without their linker symbol being referenced explicitly. For example, 222 * interrupt vector handlers, or functions in the kernel image that are found 223 * programatically. 224 * 225 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those 226 * are handled in their own way (with KEEP() in linker scripts). 227 * 228 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the 229 * linker script. For example an architecture could KEEP() its entire 230 * boot/exception vector code rather than annotate each function and data. 231 */ 232 #ifndef KENTRY 233 # define KENTRY(sym) \ 234 extern typeof(sym) sym; \ 235 static const unsigned long __kentry_##sym \ 236 __used \ 237 __attribute__((section("___kentry" "+" #sym ), used)) \ 238 = (unsigned long)&sym; 239 #endif 240 241 #ifndef RELOC_HIDE 242 # define RELOC_HIDE(ptr, off) \ 243 ({ unsigned long __ptr; \ 244 __ptr = (unsigned long) (ptr); \ 245 (typeof(ptr)) (__ptr + (off)); }) 246 #endif 247 248 #ifndef OPTIMIZER_HIDE_VAR 249 #define OPTIMIZER_HIDE_VAR(var) barrier() 250 #endif 251 252 /* Not-quite-unique ID. */ 253 #ifndef __UNIQUE_ID 254 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 255 #endif 256 257 #include <uapi/linux/types.h> 258 259 #define __READ_ONCE_SIZE \ 260 ({ \ 261 switch (size) { \ 262 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ 263 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ 264 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ 265 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ 266 default: \ 267 barrier(); \ 268 __builtin_memcpy((void *)res, (const void *)p, size); \ 269 barrier(); \ 270 } \ 271 }) 272 273 static __always_inline 274 void __read_once_size(const volatile void *p, void *res, int size) 275 { 276 __READ_ONCE_SIZE; 277 } 278 279 #ifdef CONFIG_KASAN 280 /* 281 * This function is not 'inline' because __no_sanitize_address confilcts 282 * with inlining. Attempt to inline it may cause a build failure. 283 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 284 * '__maybe_unused' allows us to avoid defined-but-not-used warnings. 285 */ 286 static __no_sanitize_address __maybe_unused 287 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 288 { 289 __READ_ONCE_SIZE; 290 } 291 #else 292 static __always_inline 293 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 294 { 295 __READ_ONCE_SIZE; 296 } 297 #endif 298 299 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 300 { 301 switch (size) { 302 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 303 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 304 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 305 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 306 default: 307 barrier(); 308 __builtin_memcpy((void *)p, (const void *)res, size); 309 barrier(); 310 } 311 } 312 313 /* 314 * Prevent the compiler from merging or refetching reads or writes. The 315 * compiler is also forbidden from reordering successive instances of 316 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the 317 * compiler is aware of some particular ordering. One way to make the 318 * compiler aware of ordering is to put the two invocations of READ_ONCE, 319 * WRITE_ONCE or ACCESS_ONCE() in different C statements. 320 * 321 * In contrast to ACCESS_ONCE these two macros will also work on aggregate 322 * data types like structs or unions. If the size of the accessed data 323 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) 324 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at 325 * least two memcpy()s: one for the __builtin_memcpy() and then one for 326 * the macro doing the copy of variable - '__u' allocated on the stack. 327 * 328 * Their two major use cases are: (1) Mediating communication between 329 * process-level code and irq/NMI handlers, all running on the same CPU, 330 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 331 * mutilate accesses that either do not require ordering or that interact 332 * with an explicit memory barrier or atomic instruction that provides the 333 * required ordering. 334 */ 335 336 #define __READ_ONCE(x, check) \ 337 ({ \ 338 union { typeof(x) __val; char __c[1]; } __u; \ 339 if (check) \ 340 __read_once_size(&(x), __u.__c, sizeof(x)); \ 341 else \ 342 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 343 __u.__val; \ 344 }) 345 #define READ_ONCE(x) __READ_ONCE(x, 1) 346 347 /* 348 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 349 * to hide memory access from KASAN. 350 */ 351 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 352 353 #define WRITE_ONCE(x, val) \ 354 ({ \ 355 union { typeof(x) __val; char __c[1]; } __u = \ 356 { .__val = (__force typeof(x)) (val) }; \ 357 __write_once_size(&(x), __u.__c, sizeof(x)); \ 358 __u.__val; \ 359 }) 360 361 #endif /* __KERNEL__ */ 362 363 #endif /* __ASSEMBLY__ */ 364 365 #ifdef __KERNEL__ 366 /* 367 * Allow us to mark functions as 'deprecated' and have gcc emit a nice 368 * warning for each use, in hopes of speeding the functions removal. 369 * Usage is: 370 * int __deprecated foo(void) 371 */ 372 #ifndef __deprecated 373 # define __deprecated /* unimplemented */ 374 #endif 375 376 #ifdef MODULE 377 #define __deprecated_for_modules __deprecated 378 #else 379 #define __deprecated_for_modules 380 #endif 381 382 #ifndef __must_check 383 #define __must_check 384 #endif 385 386 #ifndef CONFIG_ENABLE_MUST_CHECK 387 #undef __must_check 388 #define __must_check 389 #endif 390 #ifndef CONFIG_ENABLE_WARN_DEPRECATED 391 #undef __deprecated 392 #undef __deprecated_for_modules 393 #define __deprecated 394 #define __deprecated_for_modules 395 #endif 396 397 #ifndef __malloc 398 #define __malloc 399 #endif 400 401 /* 402 * Allow us to avoid 'defined but not used' warnings on functions and data, 403 * as well as force them to be emitted to the assembly file. 404 * 405 * As of gcc 3.4, static functions that are not marked with attribute((used)) 406 * may be elided from the assembly file. As of gcc 3.4, static data not so 407 * marked will not be elided, but this may change in a future gcc version. 408 * 409 * NOTE: Because distributions shipped with a backported unit-at-a-time 410 * compiler in gcc 3.3, we must define __used to be __attribute__((used)) 411 * for gcc >=3.3 instead of 3.4. 412 * 413 * In prior versions of gcc, such functions and data would be emitted, but 414 * would be warned about except with attribute((unused)). 415 * 416 * Mark functions that are referenced only in inline assembly as __used so 417 * the code is emitted even though it appears to be unreferenced. 418 */ 419 #ifndef __used 420 # define __used /* unimplemented */ 421 #endif 422 423 #ifndef __maybe_unused 424 # define __maybe_unused /* unimplemented */ 425 #endif 426 427 #ifndef __always_unused 428 # define __always_unused /* unimplemented */ 429 #endif 430 431 #ifndef noinline 432 #define noinline 433 #endif 434 435 /* 436 * Rather then using noinline to prevent stack consumption, use 437 * noinline_for_stack instead. For documentation reasons. 438 */ 439 #define noinline_for_stack noinline 440 441 #ifndef __always_inline 442 #define __always_inline inline 443 #endif 444 445 #endif /* __KERNEL__ */ 446 447 /* 448 * From the GCC manual: 449 * 450 * Many functions do not examine any values except their arguments, 451 * and have no effects except the return value. Basically this is 452 * just slightly more strict class than the `pure' attribute above, 453 * since function is not allowed to read global memory. 454 * 455 * Note that a function that has pointer arguments and examines the 456 * data pointed to must _not_ be declared `const'. Likewise, a 457 * function that calls a non-`const' function usually must not be 458 * `const'. It does not make sense for a `const' function to return 459 * `void'. 460 */ 461 #ifndef __attribute_const__ 462 # define __attribute_const__ /* unimplemented */ 463 #endif 464 465 #ifndef __designated_init 466 # define __designated_init 467 #endif 468 469 #ifndef __latent_entropy 470 # define __latent_entropy 471 #endif 472 473 #ifndef __randomize_layout 474 # define __randomize_layout __designated_init 475 #endif 476 477 #ifndef __no_randomize_layout 478 # define __no_randomize_layout 479 #endif 480 481 #ifndef randomized_struct_fields_start 482 # define randomized_struct_fields_start 483 # define randomized_struct_fields_end 484 #endif 485 486 /* 487 * Tell gcc if a function is cold. The compiler will assume any path 488 * directly leading to the call is unlikely. 489 */ 490 491 #ifndef __cold 492 #define __cold 493 #endif 494 495 /* Simple shorthand for a section definition */ 496 #ifndef __section 497 # define __section(S) __attribute__ ((__section__(#S))) 498 #endif 499 500 #ifndef __visible 501 #define __visible 502 #endif 503 504 #ifndef __nostackprotector 505 # define __nostackprotector 506 #endif 507 508 /* 509 * Assume alignment of return value. 510 */ 511 #ifndef __assume_aligned 512 #define __assume_aligned(a, ...) 513 #endif 514 515 516 /* Are two types/vars the same type (ignoring qualifiers)? */ 517 #ifndef __same_type 518 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) 519 #endif 520 521 /* Is this type a native word size -- useful for atomic operations */ 522 #ifndef __native_word 523 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) 524 #endif 525 526 /* Compile time object size, -1 for unknown */ 527 #ifndef __compiletime_object_size 528 # define __compiletime_object_size(obj) -1 529 #endif 530 #ifndef __compiletime_warning 531 # define __compiletime_warning(message) 532 #endif 533 #ifndef __compiletime_error 534 # define __compiletime_error(message) 535 /* 536 * Sparse complains of variable sized arrays due to the temporary variable in 537 * __compiletime_assert. Unfortunately we can't just expand it out to make 538 * sparse see a constant array size without breaking compiletime_assert on old 539 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. 540 */ 541 # ifndef __CHECKER__ 542 # define __compiletime_error_fallback(condition) \ 543 do { ((void)sizeof(char[1 - 2 * condition])); } while (0) 544 # endif 545 #endif 546 #ifndef __compiletime_error_fallback 547 # define __compiletime_error_fallback(condition) do { } while (0) 548 #endif 549 550 #ifdef __OPTIMIZE__ 551 # define __compiletime_assert(condition, msg, prefix, suffix) \ 552 do { \ 553 bool __cond = !(condition); \ 554 extern void prefix ## suffix(void) __compiletime_error(msg); \ 555 if (__cond) \ 556 prefix ## suffix(); \ 557 __compiletime_error_fallback(__cond); \ 558 } while (0) 559 #else 560 # define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) 561 #endif 562 563 #define _compiletime_assert(condition, msg, prefix, suffix) \ 564 __compiletime_assert(condition, msg, prefix, suffix) 565 566 /** 567 * compiletime_assert - break build and emit msg if condition is false 568 * @condition: a compile-time constant condition to check 569 * @msg: a message to emit if condition is false 570 * 571 * In tradition of POSIX assert, this macro will break the build if the 572 * supplied condition is *false*, emitting the supplied error message if the 573 * compiler has support to do so. 574 */ 575 #define compiletime_assert(condition, msg) \ 576 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 577 578 #define compiletime_assert_atomic_type(t) \ 579 compiletime_assert(__native_word(t), \ 580 "Need native word sized stores/loads for atomicity.") 581 582 /* 583 * Prevent the compiler from merging or refetching accesses. The compiler 584 * is also forbidden from reordering successive instances of ACCESS_ONCE(), 585 * but only when the compiler is aware of some particular ordering. One way 586 * to make the compiler aware of ordering is to put the two invocations of 587 * ACCESS_ONCE() in different C statements. 588 * 589 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE 590 * on a union member will work as long as the size of the member matches the 591 * size of the union and the size is smaller than word size. 592 * 593 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication 594 * between process-level code and irq/NMI handlers, all running on the same CPU, 595 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 596 * mutilate accesses that either do not require ordering or that interact 597 * with an explicit memory barrier or atomic instruction that provides the 598 * required ordering. 599 * 600 * If possible use READ_ONCE()/WRITE_ONCE() instead. 601 */ 602 #define __ACCESS_ONCE(x) ({ \ 603 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \ 604 (volatile typeof(x) *)&(x); }) 605 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) 606 607 /** 608 * lockless_dereference() - safely load a pointer for later dereference 609 * @p: The pointer to load 610 * 611 * Similar to rcu_dereference(), but for situations where the pointed-to 612 * object's lifetime is managed by something other than RCU. That 613 * "something other" might be reference counting or simple immortality. 614 * 615 * The seemingly unused variable ___typecheck_p validates that @p is 616 * indeed a pointer type by using a pointer to typeof(*p) as the type. 617 * Taking a pointer to typeof(*p) again is needed in case p is void *. 618 */ 619 #define lockless_dereference(p) \ 620 ({ \ 621 typeof(p) _________p1 = READ_ONCE(p); \ 622 typeof(*(p)) *___typecheck_p __maybe_unused; \ 623 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ 624 (_________p1); \ 625 }) 626 627 #endif /* __LINUX_COMPILER_H */ 628