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