1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __LINUX_COMPILER_H 3 #define __LINUX_COMPILER_H 4 5 #ifndef __ASSEMBLY__ 6 7 #ifdef __CHECKER__ 8 # define __user __attribute__((noderef, address_space(1))) 9 # define __kernel __attribute__((address_space(0))) 10 # define __safe __attribute__((safe)) 11 # define __force __attribute__((force)) 12 # define __nocast __attribute__((nocast)) 13 # define __iomem __attribute__((noderef, address_space(2))) 14 # define __must_hold(x) __attribute__((context(x,1,1))) 15 # define __acquires(x) __attribute__((context(x,0,1))) 16 # define __releases(x) __attribute__((context(x,1,0))) 17 # define __acquire(x) __context__(x,1) 18 # define __release(x) __context__(x,-1) 19 # define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0) 20 # define __percpu __attribute__((noderef, address_space(3))) 21 # define __rcu __attribute__((noderef, address_space(4))) 22 # define __private __attribute__((noderef)) 23 extern void __chk_user_ptr(const volatile void __user *); 24 extern void __chk_io_ptr(const volatile void __iomem *); 25 # define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member)) 26 #else /* __CHECKER__ */ 27 # ifdef STRUCTLEAK_PLUGIN 28 # define __user __attribute__((user)) 29 # else 30 # define __user 31 # endif 32 # define __kernel 33 # define __safe 34 # define __force 35 # define __nocast 36 # define __iomem 37 # define __chk_user_ptr(x) (void)0 38 # define __chk_io_ptr(x) (void)0 39 # define __builtin_warning(x, y...) (1) 40 # define __must_hold(x) 41 # define __acquires(x) 42 # define __releases(x) 43 # define __acquire(x) (void)0 44 # define __release(x) (void)0 45 # define __cond_lock(x,c) (c) 46 # define __percpu 47 # define __rcu 48 # define __private 49 # define ACCESS_PRIVATE(p, member) ((p)->member) 50 #endif /* __CHECKER__ */ 51 52 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */ 53 #define ___PASTE(a,b) a##b 54 #define __PASTE(a,b) ___PASTE(a,b) 55 56 #ifdef __KERNEL__ 57 58 #ifdef __GNUC__ 59 #include <linux/compiler-gcc.h> 60 #endif 61 62 #if defined(CC_USING_HOTPATCH) && !defined(__CHECKER__) 63 #define notrace __attribute__((hotpatch(0,0))) 64 #else 65 #define notrace __attribute__((no_instrument_function)) 66 #endif 67 68 /* Intel compiler defines __GNUC__. So we will overwrite implementations 69 * coming from above header files here 70 */ 71 #ifdef __INTEL_COMPILER 72 # include <linux/compiler-intel.h> 73 #endif 74 75 /* Clang compiler defines __GNUC__. So we will overwrite implementations 76 * coming from above header files here 77 */ 78 #ifdef __clang__ 79 #include <linux/compiler-clang.h> 80 #endif 81 82 /* 83 * Generic compiler-dependent macros required for kernel 84 * build go below this comment. Actual compiler/compiler version 85 * specific implementations come from the above header files 86 */ 87 88 struct ftrace_branch_data { 89 const char *func; 90 const char *file; 91 unsigned line; 92 union { 93 struct { 94 unsigned long correct; 95 unsigned long incorrect; 96 }; 97 struct { 98 unsigned long miss; 99 unsigned long hit; 100 }; 101 unsigned long miss_hit[2]; 102 }; 103 }; 104 105 struct ftrace_likely_data { 106 struct ftrace_branch_data data; 107 unsigned long constant; 108 }; 109 110 /* 111 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code 112 * to disable branch tracing on a per file basis. 113 */ 114 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \ 115 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) 116 void ftrace_likely_update(struct ftrace_likely_data *f, int val, 117 int expect, int is_constant); 118 119 #define likely_notrace(x) __builtin_expect(!!(x), 1) 120 #define unlikely_notrace(x) __builtin_expect(!!(x), 0) 121 122 #define __branch_check__(x, expect, is_constant) ({ \ 123 int ______r; \ 124 static struct ftrace_likely_data \ 125 __attribute__((__aligned__(4))) \ 126 __attribute__((section("_ftrace_annotated_branch"))) \ 127 ______f = { \ 128 .data.func = __func__, \ 129 .data.file = __FILE__, \ 130 .data.line = __LINE__, \ 131 }; \ 132 ______r = __builtin_expect(!!(x), expect); \ 133 ftrace_likely_update(&______f, ______r, \ 134 expect, is_constant); \ 135 ______r; \ 136 }) 137 138 /* 139 * Using __builtin_constant_p(x) to ignore cases where the return 140 * value is always the same. This idea is taken from a similar patch 141 * written by Daniel Walker. 142 */ 143 # ifndef likely 144 # define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x))) 145 # endif 146 # ifndef unlikely 147 # define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x))) 148 # endif 149 150 #ifdef CONFIG_PROFILE_ALL_BRANCHES 151 /* 152 * "Define 'is'", Bill Clinton 153 * "Define 'if'", Steven Rostedt 154 */ 155 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) ) 156 #define __trace_if(cond) \ 157 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \ 158 ({ \ 159 int ______r; \ 160 static struct ftrace_branch_data \ 161 __attribute__((__aligned__(4))) \ 162 __attribute__((section("_ftrace_branch"))) \ 163 ______f = { \ 164 .func = __func__, \ 165 .file = __FILE__, \ 166 .line = __LINE__, \ 167 }; \ 168 ______r = !!(cond); \ 169 ______f.miss_hit[______r]++; \ 170 ______r; \ 171 })) 172 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 173 174 #else 175 # define likely(x) __builtin_expect(!!(x), 1) 176 # define unlikely(x) __builtin_expect(!!(x), 0) 177 #endif 178 179 /* Optimization barrier */ 180 #ifndef barrier 181 # define barrier() __memory_barrier() 182 #endif 183 184 #ifndef barrier_data 185 # define barrier_data(ptr) barrier() 186 #endif 187 188 /* Unreachable code */ 189 #ifdef CONFIG_STACK_VALIDATION 190 #define annotate_reachable() ({ \ 191 asm("%c0:\n\t" \ 192 ".pushsection .discard.reachable\n\t" \ 193 ".long %c0b - .\n\t" \ 194 ".popsection\n\t" : : "i" (__LINE__)); \ 195 }) 196 #define annotate_unreachable() ({ \ 197 asm("%c0:\n\t" \ 198 ".pushsection .discard.unreachable\n\t" \ 199 ".long %c0b - .\n\t" \ 200 ".popsection\n\t" : : "i" (__LINE__)); \ 201 }) 202 #define ASM_UNREACHABLE \ 203 "999:\n\t" \ 204 ".pushsection .discard.unreachable\n\t" \ 205 ".long 999b - .\n\t" \ 206 ".popsection\n\t" 207 #else 208 #define annotate_reachable() 209 #define annotate_unreachable() 210 #endif 211 212 #ifndef ASM_UNREACHABLE 213 # define ASM_UNREACHABLE 214 #endif 215 #ifndef unreachable 216 # define unreachable() do { annotate_reachable(); do { } while (1); } while (0) 217 #endif 218 219 /* 220 * KENTRY - kernel entry point 221 * This can be used to annotate symbols (functions or data) that are used 222 * without their linker symbol being referenced explicitly. For example, 223 * interrupt vector handlers, or functions in the kernel image that are found 224 * programatically. 225 * 226 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those 227 * are handled in their own way (with KEEP() in linker scripts). 228 * 229 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the 230 * linker script. For example an architecture could KEEP() its entire 231 * boot/exception vector code rather than annotate each function and data. 232 */ 233 #ifndef KENTRY 234 # define KENTRY(sym) \ 235 extern typeof(sym) sym; \ 236 static const unsigned long __kentry_##sym \ 237 __used \ 238 __attribute__((section("___kentry" "+" #sym ), used)) \ 239 = (unsigned long)&sym; 240 #endif 241 242 #ifndef RELOC_HIDE 243 # define RELOC_HIDE(ptr, off) \ 244 ({ unsigned long __ptr; \ 245 __ptr = (unsigned long) (ptr); \ 246 (typeof(ptr)) (__ptr + (off)); }) 247 #endif 248 249 #ifndef OPTIMIZER_HIDE_VAR 250 #define OPTIMIZER_HIDE_VAR(var) barrier() 251 #endif 252 253 /* Not-quite-unique ID. */ 254 #ifndef __UNIQUE_ID 255 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 256 #endif 257 258 #include <uapi/linux/types.h> 259 260 #define __READ_ONCE_SIZE \ 261 ({ \ 262 switch (size) { \ 263 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ 264 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ 265 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ 266 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ 267 default: \ 268 barrier(); \ 269 __builtin_memcpy((void *)res, (const void *)p, size); \ 270 barrier(); \ 271 } \ 272 }) 273 274 static __always_inline 275 void __read_once_size(const volatile void *p, void *res, int size) 276 { 277 __READ_ONCE_SIZE; 278 } 279 280 #ifdef CONFIG_KASAN 281 /* 282 * This function is not 'inline' because __no_sanitize_address confilcts 283 * with inlining. Attempt to inline it may cause a build failure. 284 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 285 * '__maybe_unused' allows us to avoid defined-but-not-used warnings. 286 */ 287 static __no_sanitize_address __maybe_unused 288 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 289 { 290 __READ_ONCE_SIZE; 291 } 292 #else 293 static __always_inline 294 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 295 { 296 __READ_ONCE_SIZE; 297 } 298 #endif 299 300 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 301 { 302 switch (size) { 303 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 304 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 305 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 306 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 307 default: 308 barrier(); 309 __builtin_memcpy((void *)p, (const void *)res, size); 310 barrier(); 311 } 312 } 313 314 /* 315 * Prevent the compiler from merging or refetching reads or writes. The 316 * compiler is also forbidden from reordering successive instances of 317 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the 318 * compiler is aware of some particular ordering. One way to make the 319 * compiler aware of ordering is to put the two invocations of READ_ONCE, 320 * WRITE_ONCE or ACCESS_ONCE() in different C statements. 321 * 322 * In contrast to ACCESS_ONCE these two macros will also work on aggregate 323 * data types like structs or unions. If the size of the accessed data 324 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) 325 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at 326 * least two memcpy()s: one for the __builtin_memcpy() and then one for 327 * the macro doing the copy of variable - '__u' allocated on the stack. 328 * 329 * Their two major use cases are: (1) Mediating communication between 330 * process-level code and irq/NMI handlers, all running on the same CPU, 331 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 332 * mutilate accesses that either do not require ordering or that interact 333 * with an explicit memory barrier or atomic instruction that provides the 334 * required ordering. 335 */ 336 337 #define __READ_ONCE(x, check) \ 338 ({ \ 339 union { typeof(x) __val; char __c[1]; } __u; \ 340 if (check) \ 341 __read_once_size(&(x), __u.__c, sizeof(x)); \ 342 else \ 343 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 344 __u.__val; \ 345 }) 346 #define READ_ONCE(x) __READ_ONCE(x, 1) 347 348 /* 349 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 350 * to hide memory access from KASAN. 351 */ 352 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 353 354 #define WRITE_ONCE(x, val) \ 355 ({ \ 356 union { typeof(x) __val; char __c[1]; } __u = \ 357 { .__val = (__force typeof(x)) (val) }; \ 358 __write_once_size(&(x), __u.__c, sizeof(x)); \ 359 __u.__val; \ 360 }) 361 362 #endif /* __KERNEL__ */ 363 364 #endif /* __ASSEMBLY__ */ 365 366 #ifdef __KERNEL__ 367 /* 368 * Allow us to mark functions as 'deprecated' and have gcc emit a nice 369 * warning for each use, in hopes of speeding the functions removal. 370 * Usage is: 371 * int __deprecated foo(void) 372 */ 373 #ifndef __deprecated 374 # define __deprecated /* unimplemented */ 375 #endif 376 377 #ifdef MODULE 378 #define __deprecated_for_modules __deprecated 379 #else 380 #define __deprecated_for_modules 381 #endif 382 383 #ifndef __must_check 384 #define __must_check 385 #endif 386 387 #ifndef CONFIG_ENABLE_MUST_CHECK 388 #undef __must_check 389 #define __must_check 390 #endif 391 #ifndef CONFIG_ENABLE_WARN_DEPRECATED 392 #undef __deprecated 393 #undef __deprecated_for_modules 394 #define __deprecated 395 #define __deprecated_for_modules 396 #endif 397 398 #ifndef __malloc 399 #define __malloc 400 #endif 401 402 /* 403 * Allow us to avoid 'defined but not used' warnings on functions and data, 404 * as well as force them to be emitted to the assembly file. 405 * 406 * As of gcc 3.4, static functions that are not marked with attribute((used)) 407 * may be elided from the assembly file. As of gcc 3.4, static data not so 408 * marked will not be elided, but this may change in a future gcc version. 409 * 410 * NOTE: Because distributions shipped with a backported unit-at-a-time 411 * compiler in gcc 3.3, we must define __used to be __attribute__((used)) 412 * for gcc >=3.3 instead of 3.4. 413 * 414 * In prior versions of gcc, such functions and data would be emitted, but 415 * would be warned about except with attribute((unused)). 416 * 417 * Mark functions that are referenced only in inline assembly as __used so 418 * the code is emitted even though it appears to be unreferenced. 419 */ 420 #ifndef __used 421 # define __used /* unimplemented */ 422 #endif 423 424 #ifndef __maybe_unused 425 # define __maybe_unused /* unimplemented */ 426 #endif 427 428 #ifndef __always_unused 429 # define __always_unused /* unimplemented */ 430 #endif 431 432 #ifndef noinline 433 #define noinline 434 #endif 435 436 /* 437 * Rather then using noinline to prevent stack consumption, use 438 * noinline_for_stack instead. For documentation reasons. 439 */ 440 #define noinline_for_stack noinline 441 442 #ifndef __always_inline 443 #define __always_inline inline 444 #endif 445 446 #endif /* __KERNEL__ */ 447 448 /* 449 * From the GCC manual: 450 * 451 * Many functions do not examine any values except their arguments, 452 * and have no effects except the return value. Basically this is 453 * just slightly more strict class than the `pure' attribute above, 454 * since function is not allowed to read global memory. 455 * 456 * Note that a function that has pointer arguments and examines the 457 * data pointed to must _not_ be declared `const'. Likewise, a 458 * function that calls a non-`const' function usually must not be 459 * `const'. It does not make sense for a `const' function to return 460 * `void'. 461 */ 462 #ifndef __attribute_const__ 463 # define __attribute_const__ /* unimplemented */ 464 #endif 465 466 #ifndef __designated_init 467 # define __designated_init 468 #endif 469 470 #ifndef __latent_entropy 471 # define __latent_entropy 472 #endif 473 474 #ifndef __randomize_layout 475 # define __randomize_layout __designated_init 476 #endif 477 478 #ifndef __no_randomize_layout 479 # define __no_randomize_layout 480 #endif 481 482 #ifndef randomized_struct_fields_start 483 # define randomized_struct_fields_start 484 # define randomized_struct_fields_end 485 #endif 486 487 /* 488 * Tell gcc if a function is cold. The compiler will assume any path 489 * directly leading to the call is unlikely. 490 */ 491 492 #ifndef __cold 493 #define __cold 494 #endif 495 496 /* Simple shorthand for a section definition */ 497 #ifndef __section 498 # define __section(S) __attribute__ ((__section__(#S))) 499 #endif 500 501 #ifndef __visible 502 #define __visible 503 #endif 504 505 #ifndef __nostackprotector 506 # define __nostackprotector 507 #endif 508 509 /* 510 * Assume alignment of return value. 511 */ 512 #ifndef __assume_aligned 513 #define __assume_aligned(a, ...) 514 #endif 515 516 517 /* Are two types/vars the same type (ignoring qualifiers)? */ 518 #ifndef __same_type 519 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) 520 #endif 521 522 /* Is this type a native word size -- useful for atomic operations */ 523 #ifndef __native_word 524 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) 525 #endif 526 527 /* Compile time object size, -1 for unknown */ 528 #ifndef __compiletime_object_size 529 # define __compiletime_object_size(obj) -1 530 #endif 531 #ifndef __compiletime_warning 532 # define __compiletime_warning(message) 533 #endif 534 #ifndef __compiletime_error 535 # define __compiletime_error(message) 536 /* 537 * Sparse complains of variable sized arrays due to the temporary variable in 538 * __compiletime_assert. Unfortunately we can't just expand it out to make 539 * sparse see a constant array size without breaking compiletime_assert on old 540 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. 541 */ 542 # ifndef __CHECKER__ 543 # define __compiletime_error_fallback(condition) \ 544 do { ((void)sizeof(char[1 - 2 * condition])); } while (0) 545 # endif 546 #endif 547 #ifndef __compiletime_error_fallback 548 # define __compiletime_error_fallback(condition) do { } while (0) 549 #endif 550 551 #ifdef __OPTIMIZE__ 552 # define __compiletime_assert(condition, msg, prefix, suffix) \ 553 do { \ 554 bool __cond = !(condition); \ 555 extern void prefix ## suffix(void) __compiletime_error(msg); \ 556 if (__cond) \ 557 prefix ## suffix(); \ 558 __compiletime_error_fallback(__cond); \ 559 } while (0) 560 #else 561 # define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) 562 #endif 563 564 #define _compiletime_assert(condition, msg, prefix, suffix) \ 565 __compiletime_assert(condition, msg, prefix, suffix) 566 567 /** 568 * compiletime_assert - break build and emit msg if condition is false 569 * @condition: a compile-time constant condition to check 570 * @msg: a message to emit if condition is false 571 * 572 * In tradition of POSIX assert, this macro will break the build if the 573 * supplied condition is *false*, emitting the supplied error message if the 574 * compiler has support to do so. 575 */ 576 #define compiletime_assert(condition, msg) \ 577 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 578 579 #define compiletime_assert_atomic_type(t) \ 580 compiletime_assert(__native_word(t), \ 581 "Need native word sized stores/loads for atomicity.") 582 583 /* 584 * Prevent the compiler from merging or refetching accesses. The compiler 585 * is also forbidden from reordering successive instances of ACCESS_ONCE(), 586 * but only when the compiler is aware of some particular ordering. One way 587 * to make the compiler aware of ordering is to put the two invocations of 588 * ACCESS_ONCE() in different C statements. 589 * 590 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE 591 * on a union member will work as long as the size of the member matches the 592 * size of the union and the size is smaller than word size. 593 * 594 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication 595 * between process-level code and irq/NMI handlers, all running on the same CPU, 596 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 597 * mutilate accesses that either do not require ordering or that interact 598 * with an explicit memory barrier or atomic instruction that provides the 599 * required ordering. 600 * 601 * If possible use READ_ONCE()/WRITE_ONCE() instead. 602 */ 603 #define __ACCESS_ONCE(x) ({ \ 604 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \ 605 (volatile typeof(x) *)&(x); }) 606 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) 607 608 /** 609 * lockless_dereference() - safely load a pointer for later dereference 610 * @p: The pointer to load 611 * 612 * Similar to rcu_dereference(), but for situations where the pointed-to 613 * object's lifetime is managed by something other than RCU. That 614 * "something other" might be reference counting or simple immortality. 615 * 616 * The seemingly unused variable ___typecheck_p validates that @p is 617 * indeed a pointer type by using a pointer to typeof(*p) as the type. 618 * Taking a pointer to typeof(*p) again is needed in case p is void *. 619 */ 620 #define lockless_dereference(p) \ 621 ({ \ 622 typeof(p) _________p1 = READ_ONCE(p); \ 623 typeof(*(p)) *___typecheck_p __maybe_unused; \ 624 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ 625 (_________p1); \ 626 }) 627 628 #endif /* __LINUX_COMPILER_H */ 629