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 __aligned(4) \ 27 __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 __aligned(4) \ 63 __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 { \ 119 annotate_unreachable(); \ 120 __builtin_unreachable(); \ 121 } while (0) 122 #endif 123 124 /* 125 * KENTRY - kernel entry point 126 * This can be used to annotate symbols (functions or data) that are used 127 * without their linker symbol being referenced explicitly. For example, 128 * interrupt vector handlers, or functions in the kernel image that are found 129 * programatically. 130 * 131 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those 132 * are handled in their own way (with KEEP() in linker scripts). 133 * 134 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the 135 * linker script. For example an architecture could KEEP() its entire 136 * boot/exception vector code rather than annotate each function and data. 137 */ 138 #ifndef KENTRY 139 # define KENTRY(sym) \ 140 extern typeof(sym) sym; \ 141 static const unsigned long __kentry_##sym \ 142 __used \ 143 __section("___kentry" "+" #sym ) \ 144 = (unsigned long)&sym; 145 #endif 146 147 #ifndef RELOC_HIDE 148 # define RELOC_HIDE(ptr, off) \ 149 ({ unsigned long __ptr; \ 150 __ptr = (unsigned long) (ptr); \ 151 (typeof(ptr)) (__ptr + (off)); }) 152 #endif 153 154 #ifndef OPTIMIZER_HIDE_VAR 155 #define OPTIMIZER_HIDE_VAR(var) barrier() 156 #endif 157 158 /* Not-quite-unique ID. */ 159 #ifndef __UNIQUE_ID 160 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 161 #endif 162 163 #include <uapi/linux/types.h> 164 165 #define __READ_ONCE_SIZE \ 166 ({ \ 167 switch (size) { \ 168 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ 169 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ 170 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ 171 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ 172 default: \ 173 barrier(); \ 174 __builtin_memcpy((void *)res, (const void *)p, size); \ 175 barrier(); \ 176 } \ 177 }) 178 179 static __always_inline 180 void __read_once_size(const volatile void *p, void *res, int size) 181 { 182 __READ_ONCE_SIZE; 183 } 184 185 #ifdef CONFIG_KASAN 186 /* 187 * We can't declare function 'inline' because __no_sanitize_address confilcts 188 * with inlining. Attempt to inline it may cause a build failure. 189 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 190 * '__maybe_unused' allows us to avoid defined-but-not-used warnings. 191 */ 192 # define __no_kasan_or_inline __no_sanitize_address __maybe_unused 193 #else 194 # define __no_kasan_or_inline __always_inline 195 #endif 196 197 static __no_kasan_or_inline 198 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 199 { 200 __READ_ONCE_SIZE; 201 } 202 203 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 204 { 205 switch (size) { 206 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 207 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 208 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 209 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 210 default: 211 barrier(); 212 __builtin_memcpy((void *)p, (const void *)res, size); 213 barrier(); 214 } 215 } 216 217 /* 218 * Prevent the compiler from merging or refetching reads or writes. The 219 * compiler is also forbidden from reordering successive instances of 220 * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some 221 * particular ordering. One way to make the compiler aware of ordering is to 222 * put the two invocations of READ_ONCE or WRITE_ONCE in different C 223 * statements. 224 * 225 * These two macros will also work on aggregate data types like structs or 226 * unions. If the size of the accessed data type exceeds the word size of 227 * the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will 228 * fall back to memcpy(). There's at least two memcpy()s: one for the 229 * __builtin_memcpy() and then one for the macro doing the copy of variable 230 * - '__u' allocated on the stack. 231 * 232 * Their two major use cases are: (1) Mediating communication between 233 * process-level code and irq/NMI handlers, all running on the same CPU, 234 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 235 * mutilate accesses that either do not require ordering or that interact 236 * with an explicit memory barrier or atomic instruction that provides the 237 * required ordering. 238 */ 239 #include <asm/barrier.h> 240 #include <linux/kasan-checks.h> 241 242 #define __READ_ONCE(x, check) \ 243 ({ \ 244 union { typeof(x) __val; char __c[1]; } __u; \ 245 if (check) \ 246 __read_once_size(&(x), __u.__c, sizeof(x)); \ 247 else \ 248 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 249 smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ 250 __u.__val; \ 251 }) 252 #define READ_ONCE(x) __READ_ONCE(x, 1) 253 254 /* 255 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 256 * to hide memory access from KASAN. 257 */ 258 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 259 260 static __no_kasan_or_inline 261 unsigned long read_word_at_a_time(const void *addr) 262 { 263 kasan_check_read(addr, 1); 264 return *(unsigned long *)addr; 265 } 266 267 #define WRITE_ONCE(x, val) \ 268 ({ \ 269 union { typeof(x) __val; char __c[1]; } __u = \ 270 { .__val = (__force typeof(x)) (val) }; \ 271 __write_once_size(&(x), __u.__c, sizeof(x)); \ 272 __u.__val; \ 273 }) 274 275 #endif /* __KERNEL__ */ 276 277 /* 278 * Force the compiler to emit 'sym' as a symbol, so that we can reference 279 * it from inline assembler. Necessary in case 'sym' could be inlined 280 * otherwise, or eliminated entirely due to lack of references that are 281 * visible to the compiler. 282 */ 283 #define __ADDRESSABLE(sym) \ 284 static void * __section(".discard.addressable") __used \ 285 __PASTE(__addressable_##sym, __LINE__) = (void *)&sym; 286 287 /** 288 * offset_to_ptr - convert a relative memory offset to an absolute pointer 289 * @off: the address of the 32-bit offset value 290 */ 291 static inline void *offset_to_ptr(const int *off) 292 { 293 return (void *)((unsigned long)off + *off); 294 } 295 296 #else /* __ASSEMBLY__ */ 297 298 #ifdef __KERNEL__ 299 #ifndef LINKER_SCRIPT 300 301 #ifdef CONFIG_STACK_VALIDATION 302 .macro ANNOTATE_UNREACHABLE counter:req 303 \counter: 304 .pushsection .discard.unreachable 305 .long \counter\()b -. 306 .popsection 307 .endm 308 309 .macro ANNOTATE_REACHABLE counter:req 310 \counter: 311 .pushsection .discard.reachable 312 .long \counter\()b -. 313 .popsection 314 .endm 315 316 .macro ASM_UNREACHABLE 317 999: 318 .pushsection .discard.unreachable 319 .long 999b - . 320 .popsection 321 .endm 322 #else /* CONFIG_STACK_VALIDATION */ 323 .macro ANNOTATE_UNREACHABLE counter:req 324 .endm 325 326 .macro ANNOTATE_REACHABLE counter:req 327 .endm 328 329 .macro ASM_UNREACHABLE 330 .endm 331 #endif /* CONFIG_STACK_VALIDATION */ 332 333 #endif /* LINKER_SCRIPT */ 334 #endif /* __KERNEL__ */ 335 #endif /* __ASSEMBLY__ */ 336 337 /* Compile time object size, -1 for unknown */ 338 #ifndef __compiletime_object_size 339 # define __compiletime_object_size(obj) -1 340 #endif 341 #ifndef __compiletime_warning 342 # define __compiletime_warning(message) 343 #endif 344 #ifndef __compiletime_error 345 # define __compiletime_error(message) 346 #endif 347 348 #ifdef __OPTIMIZE__ 349 # define __compiletime_assert(condition, msg, prefix, suffix) \ 350 do { \ 351 extern void prefix ## suffix(void) __compiletime_error(msg); \ 352 if (!(condition)) \ 353 prefix ## suffix(); \ 354 } while (0) 355 #else 356 # define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) 357 #endif 358 359 #define _compiletime_assert(condition, msg, prefix, suffix) \ 360 __compiletime_assert(condition, msg, prefix, suffix) 361 362 /** 363 * compiletime_assert - break build and emit msg if condition is false 364 * @condition: a compile-time constant condition to check 365 * @msg: a message to emit if condition is false 366 * 367 * In tradition of POSIX assert, this macro will break the build if the 368 * supplied condition is *false*, emitting the supplied error message if the 369 * compiler has support to do so. 370 */ 371 #define compiletime_assert(condition, msg) \ 372 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 373 374 #define compiletime_assert_atomic_type(t) \ 375 compiletime_assert(__native_word(t), \ 376 "Need native word sized stores/loads for atomicity.") 377 378 /* &a[0] degrades to a pointer: a different type from an array */ 379 #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) 380 381 #endif /* __LINUX_COMPILER_H */ 382