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