1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __LINUX_COMPILER_H 3 #define __LINUX_COMPILER_H 4 5 #include <linux/compiler_types.h> 6 7 #ifndef __ASSEMBLY__ 8 9 #ifdef __KERNEL__ 10 11 /* 12 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code 13 * to disable branch tracing on a per file basis. 14 */ 15 #if defined(CONFIG_TRACE_BRANCH_PROFILING) \ 16 && !defined(DISABLE_BRANCH_PROFILING) && !defined(__CHECKER__) 17 void ftrace_likely_update(struct ftrace_likely_data *f, int val, 18 int expect, int is_constant); 19 20 #define likely_notrace(x) __builtin_expect(!!(x), 1) 21 #define unlikely_notrace(x) __builtin_expect(!!(x), 0) 22 23 #define __branch_check__(x, expect, is_constant) ({ \ 24 long ______r; \ 25 static struct ftrace_likely_data \ 26 __attribute__((__aligned__(4))) \ 27 __attribute__((section("_ftrace_annotated_branch"))) \ 28 ______f = { \ 29 .data.func = __func__, \ 30 .data.file = __FILE__, \ 31 .data.line = __LINE__, \ 32 }; \ 33 ______r = __builtin_expect(!!(x), expect); \ 34 ftrace_likely_update(&______f, ______r, \ 35 expect, is_constant); \ 36 ______r; \ 37 }) 38 39 /* 40 * Using __builtin_constant_p(x) to ignore cases where the return 41 * value is always the same. This idea is taken from a similar patch 42 * written by Daniel Walker. 43 */ 44 # ifndef likely 45 # define likely(x) (__branch_check__(x, 1, __builtin_constant_p(x))) 46 # endif 47 # ifndef unlikely 48 # define unlikely(x) (__branch_check__(x, 0, __builtin_constant_p(x))) 49 # endif 50 51 #ifdef CONFIG_PROFILE_ALL_BRANCHES 52 /* 53 * "Define 'is'", Bill Clinton 54 * "Define 'if'", Steven Rostedt 55 */ 56 #define if(cond, ...) __trace_if( (cond , ## __VA_ARGS__) ) 57 #define __trace_if(cond) \ 58 if (__builtin_constant_p(!!(cond)) ? !!(cond) : \ 59 ({ \ 60 int ______r; \ 61 static struct ftrace_branch_data \ 62 __attribute__((__aligned__(4))) \ 63 __attribute__((section("_ftrace_branch"))) \ 64 ______f = { \ 65 .func = __func__, \ 66 .file = __FILE__, \ 67 .line = __LINE__, \ 68 }; \ 69 ______r = !!(cond); \ 70 ______f.miss_hit[______r]++; \ 71 ______r; \ 72 })) 73 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 74 75 #else 76 # define likely(x) __builtin_expect(!!(x), 1) 77 # define unlikely(x) __builtin_expect(!!(x), 0) 78 #endif 79 80 /* Optimization barrier */ 81 #ifndef barrier 82 # define barrier() __memory_barrier() 83 #endif 84 85 #ifndef barrier_data 86 # define barrier_data(ptr) barrier() 87 #endif 88 89 /* workaround for GCC PR82365 if needed */ 90 #ifndef barrier_before_unreachable 91 # define barrier_before_unreachable() do { } while (0) 92 #endif 93 94 /* Unreachable code */ 95 #ifdef CONFIG_STACK_VALIDATION 96 /* 97 * These macros help objtool understand GCC code flow for unreachable code. 98 * The __COUNTER__ based labels are a hack to make each instance of the macros 99 * unique, to convince GCC not to merge duplicate inline asm statements. 100 */ 101 #define annotate_reachable() ({ \ 102 asm volatile("ANNOTATE_REACHABLE counter=%c0" \ 103 : : "i" (__COUNTER__)); \ 104 }) 105 #define annotate_unreachable() ({ \ 106 asm volatile("ANNOTATE_UNREACHABLE counter=%c0" \ 107 : : "i" (__COUNTER__)); \ 108 }) 109 #else 110 #define annotate_reachable() 111 #define annotate_unreachable() 112 #endif 113 114 #ifndef ASM_UNREACHABLE 115 # define ASM_UNREACHABLE 116 #endif 117 #ifndef unreachable 118 # define unreachable() do { annotate_reachable(); do { } while (1); } while (0) 119 #endif 120 121 /* 122 * KENTRY - kernel entry point 123 * This can be used to annotate symbols (functions or data) that are used 124 * without their linker symbol being referenced explicitly. For example, 125 * interrupt vector handlers, or functions in the kernel image that are found 126 * programatically. 127 * 128 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those 129 * are handled in their own way (with KEEP() in linker scripts). 130 * 131 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the 132 * linker script. For example an architecture could KEEP() its entire 133 * boot/exception vector code rather than annotate each function and data. 134 */ 135 #ifndef KENTRY 136 # define KENTRY(sym) \ 137 extern typeof(sym) sym; \ 138 static const unsigned long __kentry_##sym \ 139 __used \ 140 __attribute__((section("___kentry" "+" #sym ), used)) \ 141 = (unsigned long)&sym; 142 #endif 143 144 #ifndef RELOC_HIDE 145 # define RELOC_HIDE(ptr, off) \ 146 ({ unsigned long __ptr; \ 147 __ptr = (unsigned long) (ptr); \ 148 (typeof(ptr)) (__ptr + (off)); }) 149 #endif 150 151 #ifndef OPTIMIZER_HIDE_VAR 152 #define OPTIMIZER_HIDE_VAR(var) barrier() 153 #endif 154 155 /* Not-quite-unique ID. */ 156 #ifndef __UNIQUE_ID 157 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 158 #endif 159 160 #include <uapi/linux/types.h> 161 162 #define __READ_ONCE_SIZE \ 163 ({ \ 164 switch (size) { \ 165 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ 166 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ 167 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ 168 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ 169 default: \ 170 barrier(); \ 171 __builtin_memcpy((void *)res, (const void *)p, size); \ 172 barrier(); \ 173 } \ 174 }) 175 176 static __always_inline 177 void __read_once_size(const volatile void *p, void *res, int size) 178 { 179 __READ_ONCE_SIZE; 180 } 181 182 #ifdef CONFIG_KASAN 183 /* 184 * We can't declare function 'inline' because __no_sanitize_address confilcts 185 * with inlining. Attempt to inline it may cause a build failure. 186 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 187 * '__maybe_unused' allows us to avoid defined-but-not-used warnings. 188 */ 189 # define __no_kasan_or_inline __no_sanitize_address __maybe_unused 190 #else 191 # define __no_kasan_or_inline __always_inline 192 #endif 193 194 static __no_kasan_or_inline 195 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 196 { 197 __READ_ONCE_SIZE; 198 } 199 200 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 201 { 202 switch (size) { 203 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 204 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 205 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 206 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 207 default: 208 barrier(); 209 __builtin_memcpy((void *)p, (const void *)res, size); 210 barrier(); 211 } 212 } 213 214 /* 215 * Prevent the compiler from merging or refetching reads or writes. The 216 * compiler is also forbidden from reordering successive instances of 217 * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some 218 * particular ordering. One way to make the compiler aware of ordering is to 219 * put the two invocations of READ_ONCE or WRITE_ONCE in different C 220 * statements. 221 * 222 * These two macros will also work on aggregate data types like structs or 223 * unions. If the size of the accessed data type exceeds the word size of 224 * the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will 225 * fall back to memcpy(). There's at least two memcpy()s: one for the 226 * __builtin_memcpy() and then one for the macro doing the copy of variable 227 * - '__u' allocated on the stack. 228 * 229 * Their two major use cases are: (1) Mediating communication between 230 * process-level code and irq/NMI handlers, all running on the same CPU, 231 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 232 * mutilate accesses that either do not require ordering or that interact 233 * with an explicit memory barrier or atomic instruction that provides the 234 * required ordering. 235 */ 236 #include <asm/barrier.h> 237 #include <linux/kasan-checks.h> 238 239 #define __READ_ONCE(x, check) \ 240 ({ \ 241 union { typeof(x) __val; char __c[1]; } __u; \ 242 if (check) \ 243 __read_once_size(&(x), __u.__c, sizeof(x)); \ 244 else \ 245 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 246 smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ 247 __u.__val; \ 248 }) 249 #define READ_ONCE(x) __READ_ONCE(x, 1) 250 251 /* 252 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 253 * to hide memory access from KASAN. 254 */ 255 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 256 257 static __no_kasan_or_inline 258 unsigned long read_word_at_a_time(const void *addr) 259 { 260 kasan_check_read(addr, 1); 261 return *(unsigned long *)addr; 262 } 263 264 #define WRITE_ONCE(x, val) \ 265 ({ \ 266 union { typeof(x) __val; char __c[1]; } __u = \ 267 { .__val = (__force typeof(x)) (val) }; \ 268 __write_once_size(&(x), __u.__c, sizeof(x)); \ 269 __u.__val; \ 270 }) 271 272 #endif /* __KERNEL__ */ 273 274 /* 275 * Force the compiler to emit 'sym' as a symbol, so that we can reference 276 * it from inline assembler. Necessary in case 'sym' could be inlined 277 * otherwise, or eliminated entirely due to lack of references that are 278 * visible to the compiler. 279 */ 280 #define __ADDRESSABLE(sym) \ 281 static void * __attribute__((section(".discard.addressable"), used)) \ 282 __PASTE(__addressable_##sym, __LINE__) = (void *)&sym; 283 284 /** 285 * offset_to_ptr - convert a relative memory offset to an absolute pointer 286 * @off: the address of the 32-bit offset value 287 */ 288 static inline void *offset_to_ptr(const int *off) 289 { 290 return (void *)((unsigned long)off + *off); 291 } 292 293 #else /* __ASSEMBLY__ */ 294 295 #ifdef __KERNEL__ 296 #ifndef LINKER_SCRIPT 297 298 #ifdef CONFIG_STACK_VALIDATION 299 .macro ANNOTATE_UNREACHABLE counter:req 300 \counter: 301 .pushsection .discard.unreachable 302 .long \counter\()b -. 303 .popsection 304 .endm 305 306 .macro ANNOTATE_REACHABLE counter:req 307 \counter: 308 .pushsection .discard.reachable 309 .long \counter\()b -. 310 .popsection 311 .endm 312 313 .macro ASM_UNREACHABLE 314 999: 315 .pushsection .discard.unreachable 316 .long 999b - . 317 .popsection 318 .endm 319 #else /* CONFIG_STACK_VALIDATION */ 320 .macro ANNOTATE_UNREACHABLE counter:req 321 .endm 322 323 .macro ANNOTATE_REACHABLE counter:req 324 .endm 325 326 .macro ASM_UNREACHABLE 327 .endm 328 #endif /* CONFIG_STACK_VALIDATION */ 329 330 #endif /* LINKER_SCRIPT */ 331 #endif /* __KERNEL__ */ 332 #endif /* __ASSEMBLY__ */ 333 334 #ifndef __optimize 335 # define __optimize(level) 336 #endif 337 338 /* Compile time object size, -1 for unknown */ 339 #ifndef __compiletime_object_size 340 # define __compiletime_object_size(obj) -1 341 #endif 342 #ifndef __compiletime_warning 343 # define __compiletime_warning(message) 344 #endif 345 #ifndef __compiletime_error 346 # define __compiletime_error(message) 347 #endif 348 349 #ifdef __OPTIMIZE__ 350 # define __compiletime_assert(condition, msg, prefix, suffix) \ 351 do { \ 352 extern void prefix ## suffix(void) __compiletime_error(msg); \ 353 if (!(condition)) \ 354 prefix ## suffix(); \ 355 } while (0) 356 #else 357 # define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) 358 #endif 359 360 #define _compiletime_assert(condition, msg, prefix, suffix) \ 361 __compiletime_assert(condition, msg, prefix, suffix) 362 363 /** 364 * compiletime_assert - break build and emit msg if condition is false 365 * @condition: a compile-time constant condition to check 366 * @msg: a message to emit if condition is false 367 * 368 * In tradition of POSIX assert, this macro will break the build if the 369 * supplied condition is *false*, emitting the supplied error message if the 370 * compiler has support to do so. 371 */ 372 #define compiletime_assert(condition, msg) \ 373 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 374 375 #define compiletime_assert_atomic_type(t) \ 376 compiletime_assert(__native_word(t), \ 377 "Need native word sized stores/loads for atomicity.") 378 379 #endif /* __LINUX_COMPILER_H */ 380