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 #ifndef RELOC_HIDE 186 # define RELOC_HIDE(ptr, off) \ 187 ({ unsigned long __ptr; \ 188 __ptr = (unsigned long) (ptr); \ 189 (typeof(ptr)) (__ptr + (off)); }) 190 #endif 191 192 #ifndef OPTIMIZER_HIDE_VAR 193 #define OPTIMIZER_HIDE_VAR(var) barrier() 194 #endif 195 196 /* Not-quite-unique ID. */ 197 #ifndef __UNIQUE_ID 198 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 199 #endif 200 201 #include <uapi/linux/types.h> 202 203 #define __READ_ONCE_SIZE \ 204 ({ \ 205 switch (size) { \ 206 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ 207 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ 208 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ 209 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ 210 default: \ 211 barrier(); \ 212 __builtin_memcpy((void *)res, (const void *)p, size); \ 213 barrier(); \ 214 } \ 215 }) 216 217 static __always_inline 218 void __read_once_size(const volatile void *p, void *res, int size) 219 { 220 __READ_ONCE_SIZE; 221 } 222 223 #ifdef CONFIG_KASAN 224 /* 225 * This function is not 'inline' because __no_sanitize_address confilcts 226 * with inlining. Attempt to inline it may cause a build failure. 227 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 228 * '__maybe_unused' allows us to avoid defined-but-not-used warnings. 229 */ 230 static __no_sanitize_address __maybe_unused 231 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 232 { 233 __READ_ONCE_SIZE; 234 } 235 #else 236 static __always_inline 237 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 238 { 239 __READ_ONCE_SIZE; 240 } 241 #endif 242 243 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 244 { 245 switch (size) { 246 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 247 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 248 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 249 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 250 default: 251 barrier(); 252 __builtin_memcpy((void *)p, (const void *)res, size); 253 barrier(); 254 } 255 } 256 257 /* 258 * Prevent the compiler from merging or refetching reads or writes. The 259 * compiler is also forbidden from reordering successive instances of 260 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the 261 * compiler is aware of some particular ordering. One way to make the 262 * compiler aware of ordering is to put the two invocations of READ_ONCE, 263 * WRITE_ONCE or ACCESS_ONCE() in different C statements. 264 * 265 * In contrast to ACCESS_ONCE these two macros will also work on aggregate 266 * data types like structs or unions. If the size of the accessed data 267 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) 268 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at 269 * least two memcpy()s: one for the __builtin_memcpy() and then one for 270 * the macro doing the copy of variable - '__u' allocated on the stack. 271 * 272 * Their two major use cases are: (1) Mediating communication between 273 * process-level code and irq/NMI handlers, all running on the same CPU, 274 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 275 * mutilate accesses that either do not require ordering or that interact 276 * with an explicit memory barrier or atomic instruction that provides the 277 * required ordering. 278 */ 279 280 #define __READ_ONCE(x, check) \ 281 ({ \ 282 union { typeof(x) __val; char __c[1]; } __u; \ 283 if (check) \ 284 __read_once_size(&(x), __u.__c, sizeof(x)); \ 285 else \ 286 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 287 __u.__val; \ 288 }) 289 #define READ_ONCE(x) __READ_ONCE(x, 1) 290 291 /* 292 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 293 * to hide memory access from KASAN. 294 */ 295 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 296 297 #define WRITE_ONCE(x, val) \ 298 ({ \ 299 union { typeof(x) __val; char __c[1]; } __u = \ 300 { .__val = (__force typeof(x)) (val) }; \ 301 __write_once_size(&(x), __u.__c, sizeof(x)); \ 302 __u.__val; \ 303 }) 304 305 #endif /* __KERNEL__ */ 306 307 #endif /* __ASSEMBLY__ */ 308 309 #ifdef __KERNEL__ 310 /* 311 * Allow us to mark functions as 'deprecated' and have gcc emit a nice 312 * warning for each use, in hopes of speeding the functions removal. 313 * Usage is: 314 * int __deprecated foo(void) 315 */ 316 #ifndef __deprecated 317 # define __deprecated /* unimplemented */ 318 #endif 319 320 #ifdef MODULE 321 #define __deprecated_for_modules __deprecated 322 #else 323 #define __deprecated_for_modules 324 #endif 325 326 #ifndef __must_check 327 #define __must_check 328 #endif 329 330 #ifndef CONFIG_ENABLE_MUST_CHECK 331 #undef __must_check 332 #define __must_check 333 #endif 334 #ifndef CONFIG_ENABLE_WARN_DEPRECATED 335 #undef __deprecated 336 #undef __deprecated_for_modules 337 #define __deprecated 338 #define __deprecated_for_modules 339 #endif 340 341 #ifndef __malloc 342 #define __malloc 343 #endif 344 345 /* 346 * Allow us to avoid 'defined but not used' warnings on functions and data, 347 * as well as force them to be emitted to the assembly file. 348 * 349 * As of gcc 3.4, static functions that are not marked with attribute((used)) 350 * may be elided from the assembly file. As of gcc 3.4, static data not so 351 * marked will not be elided, but this may change in a future gcc version. 352 * 353 * NOTE: Because distributions shipped with a backported unit-at-a-time 354 * compiler in gcc 3.3, we must define __used to be __attribute__((used)) 355 * for gcc >=3.3 instead of 3.4. 356 * 357 * In prior versions of gcc, such functions and data would be emitted, but 358 * would be warned about except with attribute((unused)). 359 * 360 * Mark functions that are referenced only in inline assembly as __used so 361 * the code is emitted even though it appears to be unreferenced. 362 */ 363 #ifndef __used 364 # define __used /* unimplemented */ 365 #endif 366 367 #ifndef __maybe_unused 368 # define __maybe_unused /* unimplemented */ 369 #endif 370 371 #ifndef __always_unused 372 # define __always_unused /* unimplemented */ 373 #endif 374 375 #ifndef noinline 376 #define noinline 377 #endif 378 379 /* 380 * Rather then using noinline to prevent stack consumption, use 381 * noinline_for_stack instead. For documentation reasons. 382 */ 383 #define noinline_for_stack noinline 384 385 #ifndef __always_inline 386 #define __always_inline inline 387 #endif 388 389 #endif /* __KERNEL__ */ 390 391 /* 392 * From the GCC manual: 393 * 394 * Many functions do not examine any values except their arguments, 395 * and have no effects except the return value. Basically this is 396 * just slightly more strict class than the `pure' attribute above, 397 * since function is not allowed to read global memory. 398 * 399 * Note that a function that has pointer arguments and examines the 400 * data pointed to must _not_ be declared `const'. Likewise, a 401 * function that calls a non-`const' function usually must not be 402 * `const'. It does not make sense for a `const' function to return 403 * `void'. 404 */ 405 #ifndef __attribute_const__ 406 # define __attribute_const__ /* unimplemented */ 407 #endif 408 409 /* 410 * Tell gcc if a function is cold. The compiler will assume any path 411 * directly leading to the call is unlikely. 412 */ 413 414 #ifndef __cold 415 #define __cold 416 #endif 417 418 /* Simple shorthand for a section definition */ 419 #ifndef __section 420 # define __section(S) __attribute__ ((__section__(#S))) 421 #endif 422 423 #ifndef __visible 424 #define __visible 425 #endif 426 427 /* 428 * Assume alignment of return value. 429 */ 430 #ifndef __assume_aligned 431 #define __assume_aligned(a, ...) 432 #endif 433 434 435 /* Are two types/vars the same type (ignoring qualifiers)? */ 436 #ifndef __same_type 437 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) 438 #endif 439 440 /* Is this type a native word size -- useful for atomic operations */ 441 #ifndef __native_word 442 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) 443 #endif 444 445 /* Compile time object size, -1 for unknown */ 446 #ifndef __compiletime_object_size 447 # define __compiletime_object_size(obj) -1 448 #endif 449 #ifndef __compiletime_warning 450 # define __compiletime_warning(message) 451 #endif 452 #ifndef __compiletime_error 453 # define __compiletime_error(message) 454 /* 455 * Sparse complains of variable sized arrays due to the temporary variable in 456 * __compiletime_assert. Unfortunately we can't just expand it out to make 457 * sparse see a constant array size without breaking compiletime_assert on old 458 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. 459 */ 460 # ifndef __CHECKER__ 461 # define __compiletime_error_fallback(condition) \ 462 do { ((void)sizeof(char[1 - 2 * condition])); } while (0) 463 # endif 464 #endif 465 #ifndef __compiletime_error_fallback 466 # define __compiletime_error_fallback(condition) do { } while (0) 467 #endif 468 469 #define __compiletime_assert(condition, msg, prefix, suffix) \ 470 do { \ 471 bool __cond = !(condition); \ 472 extern void prefix ## suffix(void) __compiletime_error(msg); \ 473 if (__cond) \ 474 prefix ## suffix(); \ 475 __compiletime_error_fallback(__cond); \ 476 } while (0) 477 478 #define _compiletime_assert(condition, msg, prefix, suffix) \ 479 __compiletime_assert(condition, msg, prefix, suffix) 480 481 /** 482 * compiletime_assert - break build and emit msg if condition is false 483 * @condition: a compile-time constant condition to check 484 * @msg: a message to emit if condition is false 485 * 486 * In tradition of POSIX assert, this macro will break the build if the 487 * supplied condition is *false*, emitting the supplied error message if the 488 * compiler has support to do so. 489 */ 490 #define compiletime_assert(condition, msg) \ 491 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 492 493 #define compiletime_assert_atomic_type(t) \ 494 compiletime_assert(__native_word(t), \ 495 "Need native word sized stores/loads for atomicity.") 496 497 /* 498 * Prevent the compiler from merging or refetching accesses. The compiler 499 * is also forbidden from reordering successive instances of ACCESS_ONCE(), 500 * but only when the compiler is aware of some particular ordering. One way 501 * to make the compiler aware of ordering is to put the two invocations of 502 * ACCESS_ONCE() in different C statements. 503 * 504 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE 505 * on a union member will work as long as the size of the member matches the 506 * size of the union and the size is smaller than word size. 507 * 508 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication 509 * between process-level code and irq/NMI handlers, all running on the same CPU, 510 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 511 * mutilate accesses that either do not require ordering or that interact 512 * with an explicit memory barrier or atomic instruction that provides the 513 * required ordering. 514 * 515 * If possible use READ_ONCE()/WRITE_ONCE() instead. 516 */ 517 #define __ACCESS_ONCE(x) ({ \ 518 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \ 519 (volatile typeof(x) *)&(x); }) 520 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) 521 522 /** 523 * lockless_dereference() - safely load a pointer for later dereference 524 * @p: The pointer to load 525 * 526 * Similar to rcu_dereference(), but for situations where the pointed-to 527 * object's lifetime is managed by something other than RCU. That 528 * "something other" might be reference counting or simple immortality. 529 * 530 * The seemingly unused size_t variable is to validate @p is indeed a pointer 531 * type by making sure it can be dereferenced. 532 */ 533 #define lockless_dereference(p) \ 534 ({ \ 535 typeof(p) _________p1 = READ_ONCE(p); \ 536 size_t __maybe_unused __size_of_ptr = sizeof(*(p)); \ 537 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ 538 (_________p1); \ 539 }) 540 541 /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */ 542 #ifdef CONFIG_KPROBES 543 # define __kprobes __attribute__((__section__(".kprobes.text"))) 544 # define nokprobe_inline __always_inline 545 #else 546 # define __kprobes 547 # define nokprobe_inline inline 548 #endif 549 #endif /* __LINUX_COMPILER_H */ 550