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 /* 191 * These macros help objtool understand GCC code flow for unreachable code. 192 * The __COUNTER__ based labels are a hack to make each instance of the macros 193 * unique, to convince GCC not to merge duplicate inline asm statements. 194 */ 195 #define annotate_reachable() ({ \ 196 asm volatile("%c0:\n\t" \ 197 ".pushsection .discard.reachable\n\t" \ 198 ".long %c0b - .\n\t" \ 199 ".popsection\n\t" : : "i" (__COUNTER__)); \ 200 }) 201 #define annotate_unreachable() ({ \ 202 asm volatile("%c0:\n\t" \ 203 ".pushsection .discard.unreachable\n\t" \ 204 ".long %c0b - .\n\t" \ 205 ".popsection\n\t" : : "i" (__COUNTER__)); \ 206 }) 207 #define ASM_UNREACHABLE \ 208 "999:\n\t" \ 209 ".pushsection .discard.unreachable\n\t" \ 210 ".long 999b - .\n\t" \ 211 ".popsection\n\t" 212 #else 213 #define annotate_reachable() 214 #define annotate_unreachable() 215 #endif 216 217 #ifndef ASM_UNREACHABLE 218 # define ASM_UNREACHABLE 219 #endif 220 #ifndef unreachable 221 # define unreachable() do { annotate_reachable(); do { } while (1); } while (0) 222 #endif 223 224 /* 225 * KENTRY - kernel entry point 226 * This can be used to annotate symbols (functions or data) that are used 227 * without their linker symbol being referenced explicitly. For example, 228 * interrupt vector handlers, or functions in the kernel image that are found 229 * programatically. 230 * 231 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those 232 * are handled in their own way (with KEEP() in linker scripts). 233 * 234 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the 235 * linker script. For example an architecture could KEEP() its entire 236 * boot/exception vector code rather than annotate each function and data. 237 */ 238 #ifndef KENTRY 239 # define KENTRY(sym) \ 240 extern typeof(sym) sym; \ 241 static const unsigned long __kentry_##sym \ 242 __used \ 243 __attribute__((section("___kentry" "+" #sym ), used)) \ 244 = (unsigned long)&sym; 245 #endif 246 247 #ifndef RELOC_HIDE 248 # define RELOC_HIDE(ptr, off) \ 249 ({ unsigned long __ptr; \ 250 __ptr = (unsigned long) (ptr); \ 251 (typeof(ptr)) (__ptr + (off)); }) 252 #endif 253 254 #ifndef OPTIMIZER_HIDE_VAR 255 #define OPTIMIZER_HIDE_VAR(var) barrier() 256 #endif 257 258 /* Not-quite-unique ID. */ 259 #ifndef __UNIQUE_ID 260 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 261 #endif 262 263 #include <uapi/linux/types.h> 264 265 #define __READ_ONCE_SIZE \ 266 ({ \ 267 switch (size) { \ 268 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ 269 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ 270 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ 271 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ 272 default: \ 273 barrier(); \ 274 __builtin_memcpy((void *)res, (const void *)p, size); \ 275 barrier(); \ 276 } \ 277 }) 278 279 static __always_inline 280 void __read_once_size(const volatile void *p, void *res, int size) 281 { 282 __READ_ONCE_SIZE; 283 } 284 285 #ifdef CONFIG_KASAN 286 /* 287 * This function is not 'inline' because __no_sanitize_address confilcts 288 * with inlining. Attempt to inline it may cause a build failure. 289 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 290 * '__maybe_unused' allows us to avoid defined-but-not-used warnings. 291 */ 292 static __no_sanitize_address __maybe_unused 293 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 294 { 295 __READ_ONCE_SIZE; 296 } 297 #else 298 static __always_inline 299 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 300 { 301 __READ_ONCE_SIZE; 302 } 303 #endif 304 305 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 306 { 307 switch (size) { 308 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 309 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 310 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 311 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 312 default: 313 barrier(); 314 __builtin_memcpy((void *)p, (const void *)res, size); 315 barrier(); 316 } 317 } 318 319 /* 320 * Prevent the compiler from merging or refetching reads or writes. The 321 * compiler is also forbidden from reordering successive instances of 322 * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the 323 * compiler is aware of some particular ordering. One way to make the 324 * compiler aware of ordering is to put the two invocations of READ_ONCE, 325 * WRITE_ONCE or ACCESS_ONCE() in different C statements. 326 * 327 * In contrast to ACCESS_ONCE these two macros will also work on aggregate 328 * data types like structs or unions. If the size of the accessed data 329 * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) 330 * READ_ONCE() and WRITE_ONCE() will fall back to memcpy(). There's at 331 * least two memcpy()s: one for the __builtin_memcpy() and then one for 332 * the macro doing the copy of variable - '__u' allocated on the stack. 333 * 334 * Their two major use cases are: (1) Mediating communication between 335 * process-level code and irq/NMI handlers, all running on the same CPU, 336 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 337 * mutilate accesses that either do not require ordering or that interact 338 * with an explicit memory barrier or atomic instruction that provides the 339 * required ordering. 340 */ 341 342 #define __READ_ONCE(x, check) \ 343 ({ \ 344 union { typeof(x) __val; char __c[1]; } __u; \ 345 if (check) \ 346 __read_once_size(&(x), __u.__c, sizeof(x)); \ 347 else \ 348 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 349 __u.__val; \ 350 }) 351 #define READ_ONCE(x) __READ_ONCE(x, 1) 352 353 /* 354 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 355 * to hide memory access from KASAN. 356 */ 357 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 358 359 #define WRITE_ONCE(x, val) \ 360 ({ \ 361 union { typeof(x) __val; char __c[1]; } __u = \ 362 { .__val = (__force typeof(x)) (val) }; \ 363 __write_once_size(&(x), __u.__c, sizeof(x)); \ 364 __u.__val; \ 365 }) 366 367 #endif /* __KERNEL__ */ 368 369 #endif /* __ASSEMBLY__ */ 370 371 #ifdef __KERNEL__ 372 /* 373 * Allow us to mark functions as 'deprecated' and have gcc emit a nice 374 * warning for each use, in hopes of speeding the functions removal. 375 * Usage is: 376 * int __deprecated foo(void) 377 */ 378 #ifndef __deprecated 379 # define __deprecated /* unimplemented */ 380 #endif 381 382 #ifdef MODULE 383 #define __deprecated_for_modules __deprecated 384 #else 385 #define __deprecated_for_modules 386 #endif 387 388 #ifndef __must_check 389 #define __must_check 390 #endif 391 392 #ifndef CONFIG_ENABLE_MUST_CHECK 393 #undef __must_check 394 #define __must_check 395 #endif 396 #ifndef CONFIG_ENABLE_WARN_DEPRECATED 397 #undef __deprecated 398 #undef __deprecated_for_modules 399 #define __deprecated 400 #define __deprecated_for_modules 401 #endif 402 403 #ifndef __malloc 404 #define __malloc 405 #endif 406 407 /* 408 * Allow us to avoid 'defined but not used' warnings on functions and data, 409 * as well as force them to be emitted to the assembly file. 410 * 411 * As of gcc 3.4, static functions that are not marked with attribute((used)) 412 * may be elided from the assembly file. As of gcc 3.4, static data not so 413 * marked will not be elided, but this may change in a future gcc version. 414 * 415 * NOTE: Because distributions shipped with a backported unit-at-a-time 416 * compiler in gcc 3.3, we must define __used to be __attribute__((used)) 417 * for gcc >=3.3 instead of 3.4. 418 * 419 * In prior versions of gcc, such functions and data would be emitted, but 420 * would be warned about except with attribute((unused)). 421 * 422 * Mark functions that are referenced only in inline assembly as __used so 423 * the code is emitted even though it appears to be unreferenced. 424 */ 425 #ifndef __used 426 # define __used /* unimplemented */ 427 #endif 428 429 #ifndef __maybe_unused 430 # define __maybe_unused /* unimplemented */ 431 #endif 432 433 #ifndef __always_unused 434 # define __always_unused /* unimplemented */ 435 #endif 436 437 #ifndef noinline 438 #define noinline 439 #endif 440 441 /* 442 * Rather then using noinline to prevent stack consumption, use 443 * noinline_for_stack instead. For documentation reasons. 444 */ 445 #define noinline_for_stack noinline 446 447 #ifndef __always_inline 448 #define __always_inline inline 449 #endif 450 451 #endif /* __KERNEL__ */ 452 453 /* 454 * From the GCC manual: 455 * 456 * Many functions do not examine any values except their arguments, 457 * and have no effects except the return value. Basically this is 458 * just slightly more strict class than the `pure' attribute above, 459 * since function is not allowed to read global memory. 460 * 461 * Note that a function that has pointer arguments and examines the 462 * data pointed to must _not_ be declared `const'. Likewise, a 463 * function that calls a non-`const' function usually must not be 464 * `const'. It does not make sense for a `const' function to return 465 * `void'. 466 */ 467 #ifndef __attribute_const__ 468 # define __attribute_const__ /* unimplemented */ 469 #endif 470 471 #ifndef __designated_init 472 # define __designated_init 473 #endif 474 475 #ifndef __latent_entropy 476 # define __latent_entropy 477 #endif 478 479 #ifndef __randomize_layout 480 # define __randomize_layout __designated_init 481 #endif 482 483 #ifndef __no_randomize_layout 484 # define __no_randomize_layout 485 #endif 486 487 #ifndef randomized_struct_fields_start 488 # define randomized_struct_fields_start 489 # define randomized_struct_fields_end 490 #endif 491 492 /* 493 * Tell gcc if a function is cold. The compiler will assume any path 494 * directly leading to the call is unlikely. 495 */ 496 497 #ifndef __cold 498 #define __cold 499 #endif 500 501 /* Simple shorthand for a section definition */ 502 #ifndef __section 503 # define __section(S) __attribute__ ((__section__(#S))) 504 #endif 505 506 #ifndef __visible 507 #define __visible 508 #endif 509 510 #ifndef __nostackprotector 511 # define __nostackprotector 512 #endif 513 514 /* 515 * Assume alignment of return value. 516 */ 517 #ifndef __assume_aligned 518 #define __assume_aligned(a, ...) 519 #endif 520 521 522 /* Are two types/vars the same type (ignoring qualifiers)? */ 523 #ifndef __same_type 524 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) 525 #endif 526 527 /* Is this type a native word size -- useful for atomic operations */ 528 #ifndef __native_word 529 # define __native_word(t) (sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long)) 530 #endif 531 532 /* Compile time object size, -1 for unknown */ 533 #ifndef __compiletime_object_size 534 # define __compiletime_object_size(obj) -1 535 #endif 536 #ifndef __compiletime_warning 537 # define __compiletime_warning(message) 538 #endif 539 #ifndef __compiletime_error 540 # define __compiletime_error(message) 541 /* 542 * Sparse complains of variable sized arrays due to the temporary variable in 543 * __compiletime_assert. Unfortunately we can't just expand it out to make 544 * sparse see a constant array size without breaking compiletime_assert on old 545 * versions of GCC (e.g. 4.2.4), so hide the array from sparse altogether. 546 */ 547 # ifndef __CHECKER__ 548 # define __compiletime_error_fallback(condition) \ 549 do { ((void)sizeof(char[1 - 2 * condition])); } while (0) 550 # endif 551 #endif 552 #ifndef __compiletime_error_fallback 553 # define __compiletime_error_fallback(condition) do { } while (0) 554 #endif 555 556 #ifdef __OPTIMIZE__ 557 # define __compiletime_assert(condition, msg, prefix, suffix) \ 558 do { \ 559 bool __cond = !(condition); \ 560 extern void prefix ## suffix(void) __compiletime_error(msg); \ 561 if (__cond) \ 562 prefix ## suffix(); \ 563 __compiletime_error_fallback(__cond); \ 564 } while (0) 565 #else 566 # define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) 567 #endif 568 569 #define _compiletime_assert(condition, msg, prefix, suffix) \ 570 __compiletime_assert(condition, msg, prefix, suffix) 571 572 /** 573 * compiletime_assert - break build and emit msg if condition is false 574 * @condition: a compile-time constant condition to check 575 * @msg: a message to emit if condition is false 576 * 577 * In tradition of POSIX assert, this macro will break the build if the 578 * supplied condition is *false*, emitting the supplied error message if the 579 * compiler has support to do so. 580 */ 581 #define compiletime_assert(condition, msg) \ 582 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 583 584 #define compiletime_assert_atomic_type(t) \ 585 compiletime_assert(__native_word(t), \ 586 "Need native word sized stores/loads for atomicity.") 587 588 /* 589 * Prevent the compiler from merging or refetching accesses. The compiler 590 * is also forbidden from reordering successive instances of ACCESS_ONCE(), 591 * but only when the compiler is aware of some particular ordering. One way 592 * to make the compiler aware of ordering is to put the two invocations of 593 * ACCESS_ONCE() in different C statements. 594 * 595 * ACCESS_ONCE will only work on scalar types. For union types, ACCESS_ONCE 596 * on a union member will work as long as the size of the member matches the 597 * size of the union and the size is smaller than word size. 598 * 599 * The major use cases of ACCESS_ONCE used to be (1) Mediating communication 600 * between process-level code and irq/NMI handlers, all running on the same CPU, 601 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 602 * mutilate accesses that either do not require ordering or that interact 603 * with an explicit memory barrier or atomic instruction that provides the 604 * required ordering. 605 * 606 * If possible use READ_ONCE()/WRITE_ONCE() instead. 607 */ 608 #define __ACCESS_ONCE(x) ({ \ 609 __maybe_unused typeof(x) __var = (__force typeof(x)) 0; \ 610 (volatile typeof(x) *)&(x); }) 611 #define ACCESS_ONCE(x) (*__ACCESS_ONCE(x)) 612 613 /** 614 * lockless_dereference() - safely load a pointer for later dereference 615 * @p: The pointer to load 616 * 617 * Similar to rcu_dereference(), but for situations where the pointed-to 618 * object's lifetime is managed by something other than RCU. That 619 * "something other" might be reference counting or simple immortality. 620 * 621 * The seemingly unused variable ___typecheck_p validates that @p is 622 * indeed a pointer type by using a pointer to typeof(*p) as the type. 623 * Taking a pointer to typeof(*p) again is needed in case p is void *. 624 */ 625 #define lockless_dereference(p) \ 626 ({ \ 627 typeof(p) _________p1 = READ_ONCE(p); \ 628 typeof(*(p)) *___typecheck_p __maybe_unused; \ 629 smp_read_barrier_depends(); /* Dependency order vs. p above. */ \ 630 (_________p1); \ 631 }) 632 633 #endif /* __LINUX_COMPILER_H */ 634