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, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) ) 57 58 #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond)) 59 60 #define __trace_if_value(cond) ({ \ 61 static struct ftrace_branch_data \ 62 __aligned(4) \ 63 __section("_ftrace_branch") \ 64 __if_trace = { \ 65 .func = __func__, \ 66 .file = __FILE__, \ 67 .line = __LINE__, \ 68 }; \ 69 (cond) ? \ 70 (__if_trace.miss_hit[1]++,1) : \ 71 (__if_trace.miss_hit[0]++,0); \ 72 }) 73 74 #endif /* CONFIG_PROFILE_ALL_BRANCHES */ 75 76 #else 77 # define likely(x) __builtin_expect(!!(x), 1) 78 # define unlikely(x) __builtin_expect(!!(x), 0) 79 #endif 80 81 /* Optimization barrier */ 82 #ifndef barrier 83 # define barrier() __memory_barrier() 84 #endif 85 86 #ifndef barrier_data 87 # define barrier_data(ptr) barrier() 88 #endif 89 90 /* workaround for GCC PR82365 if needed */ 91 #ifndef barrier_before_unreachable 92 # define barrier_before_unreachable() do { } while (0) 93 #endif 94 95 /* Unreachable code */ 96 #ifdef CONFIG_STACK_VALIDATION 97 /* 98 * These macros help objtool understand GCC code flow for unreachable code. 99 * The __COUNTER__ based labels are a hack to make each instance of the macros 100 * unique, to convince GCC not to merge duplicate inline asm statements. 101 */ 102 #define annotate_reachable() ({ \ 103 asm volatile("%c0:\n\t" \ 104 ".pushsection .discard.reachable\n\t" \ 105 ".long %c0b - .\n\t" \ 106 ".popsection\n\t" : : "i" (__COUNTER__)); \ 107 }) 108 #define annotate_unreachable() ({ \ 109 asm volatile("%c0:\n\t" \ 110 ".pushsection .discard.unreachable\n\t" \ 111 ".long %c0b - .\n\t" \ 112 ".popsection\n\t" : : "i" (__COUNTER__)); \ 113 }) 114 #define ASM_UNREACHABLE \ 115 "999:\n\t" \ 116 ".pushsection .discard.unreachable\n\t" \ 117 ".long 999b - .\n\t" \ 118 ".popsection\n\t" 119 #else 120 #define annotate_reachable() 121 #define annotate_unreachable() 122 #endif 123 124 #ifndef ASM_UNREACHABLE 125 # define ASM_UNREACHABLE 126 #endif 127 #ifndef unreachable 128 # define unreachable() do { \ 129 annotate_unreachable(); \ 130 __builtin_unreachable(); \ 131 } while (0) 132 #endif 133 134 /* 135 * KENTRY - kernel entry point 136 * This can be used to annotate symbols (functions or data) that are used 137 * without their linker symbol being referenced explicitly. For example, 138 * interrupt vector handlers, or functions in the kernel image that are found 139 * programatically. 140 * 141 * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those 142 * are handled in their own way (with KEEP() in linker scripts). 143 * 144 * KENTRY can be avoided if the symbols in question are marked as KEEP() in the 145 * linker script. For example an architecture could KEEP() its entire 146 * boot/exception vector code rather than annotate each function and data. 147 */ 148 #ifndef KENTRY 149 # define KENTRY(sym) \ 150 extern typeof(sym) sym; \ 151 static const unsigned long __kentry_##sym \ 152 __used \ 153 __section("___kentry" "+" #sym ) \ 154 = (unsigned long)&sym; 155 #endif 156 157 #ifndef RELOC_HIDE 158 # define RELOC_HIDE(ptr, off) \ 159 ({ unsigned long __ptr; \ 160 __ptr = (unsigned long) (ptr); \ 161 (typeof(ptr)) (__ptr + (off)); }) 162 #endif 163 164 #ifndef OPTIMIZER_HIDE_VAR 165 /* Make the optimizer believe the variable can be manipulated arbitrarily. */ 166 #define OPTIMIZER_HIDE_VAR(var) \ 167 __asm__ ("" : "=r" (var) : "0" (var)) 168 #endif 169 170 /* Not-quite-unique ID. */ 171 #ifndef __UNIQUE_ID 172 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__) 173 #endif 174 175 #include <uapi/linux/types.h> 176 177 #define __READ_ONCE_SIZE \ 178 ({ \ 179 switch (size) { \ 180 case 1: *(__u8 *)res = *(volatile __u8 *)p; break; \ 181 case 2: *(__u16 *)res = *(volatile __u16 *)p; break; \ 182 case 4: *(__u32 *)res = *(volatile __u32 *)p; break; \ 183 case 8: *(__u64 *)res = *(volatile __u64 *)p; break; \ 184 default: \ 185 barrier(); \ 186 __builtin_memcpy((void *)res, (const void *)p, size); \ 187 barrier(); \ 188 } \ 189 }) 190 191 static __always_inline 192 void __read_once_size(const volatile void *p, void *res, int size) 193 { 194 __READ_ONCE_SIZE; 195 } 196 197 #ifdef CONFIG_KASAN 198 /* 199 * We can't declare function 'inline' because __no_sanitize_address confilcts 200 * with inlining. Attempt to inline it may cause a build failure. 201 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368 202 * '__maybe_unused' allows us to avoid defined-but-not-used warnings. 203 */ 204 # define __no_kasan_or_inline __no_sanitize_address notrace __maybe_unused 205 #else 206 # define __no_kasan_or_inline __always_inline 207 #endif 208 209 static __no_kasan_or_inline 210 void __read_once_size_nocheck(const volatile void *p, void *res, int size) 211 { 212 __READ_ONCE_SIZE; 213 } 214 215 static __always_inline void __write_once_size(volatile void *p, void *res, int size) 216 { 217 switch (size) { 218 case 1: *(volatile __u8 *)p = *(__u8 *)res; break; 219 case 2: *(volatile __u16 *)p = *(__u16 *)res; break; 220 case 4: *(volatile __u32 *)p = *(__u32 *)res; break; 221 case 8: *(volatile __u64 *)p = *(__u64 *)res; break; 222 default: 223 barrier(); 224 __builtin_memcpy((void *)p, (const void *)res, size); 225 barrier(); 226 } 227 } 228 229 /* 230 * Prevent the compiler from merging or refetching reads or writes. The 231 * compiler is also forbidden from reordering successive instances of 232 * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some 233 * particular ordering. One way to make the compiler aware of ordering is to 234 * put the two invocations of READ_ONCE or WRITE_ONCE in different C 235 * statements. 236 * 237 * These two macros will also work on aggregate data types like structs or 238 * unions. If the size of the accessed data type exceeds the word size of 239 * the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will 240 * fall back to memcpy(). There's at least two memcpy()s: one for the 241 * __builtin_memcpy() and then one for the macro doing the copy of variable 242 * - '__u' allocated on the stack. 243 * 244 * Their two major use cases are: (1) Mediating communication between 245 * process-level code and irq/NMI handlers, all running on the same CPU, 246 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 247 * mutilate accesses that either do not require ordering or that interact 248 * with an explicit memory barrier or atomic instruction that provides the 249 * required ordering. 250 */ 251 #include <asm/barrier.h> 252 #include <linux/kasan-checks.h> 253 254 #define __READ_ONCE(x, check) \ 255 ({ \ 256 union { typeof(x) __val; char __c[1]; } __u; \ 257 if (check) \ 258 __read_once_size(&(x), __u.__c, sizeof(x)); \ 259 else \ 260 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 261 smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \ 262 __u.__val; \ 263 }) 264 #define READ_ONCE(x) __READ_ONCE(x, 1) 265 266 /* 267 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 268 * to hide memory access from KASAN. 269 */ 270 #define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 271 272 static __no_kasan_or_inline 273 unsigned long read_word_at_a_time(const void *addr) 274 { 275 kasan_check_read(addr, 1); 276 return *(unsigned long *)addr; 277 } 278 279 #define WRITE_ONCE(x, val) \ 280 ({ \ 281 union { typeof(x) __val; char __c[1]; } __u = \ 282 { .__val = (__force typeof(x)) (val) }; \ 283 __write_once_size(&(x), __u.__c, sizeof(x)); \ 284 __u.__val; \ 285 }) 286 287 #endif /* __KERNEL__ */ 288 289 /* 290 * Force the compiler to emit 'sym' as a symbol, so that we can reference 291 * it from inline assembler. Necessary in case 'sym' could be inlined 292 * otherwise, or eliminated entirely due to lack of references that are 293 * visible to the compiler. 294 */ 295 #define __ADDRESSABLE(sym) \ 296 static void * __section(".discard.addressable") __used \ 297 __PASTE(__addressable_##sym, __LINE__) = (void *)&sym; 298 299 /** 300 * offset_to_ptr - convert a relative memory offset to an absolute pointer 301 * @off: the address of the 32-bit offset value 302 */ 303 static inline void *offset_to_ptr(const int *off) 304 { 305 return (void *)((unsigned long)off + *off); 306 } 307 308 #endif /* __ASSEMBLY__ */ 309 310 /* Compile time object size, -1 for unknown */ 311 #ifndef __compiletime_object_size 312 # define __compiletime_object_size(obj) -1 313 #endif 314 #ifndef __compiletime_warning 315 # define __compiletime_warning(message) 316 #endif 317 #ifndef __compiletime_error 318 # define __compiletime_error(message) 319 #endif 320 321 #ifdef __OPTIMIZE__ 322 # define __compiletime_assert(condition, msg, prefix, suffix) \ 323 do { \ 324 extern void prefix ## suffix(void) __compiletime_error(msg); \ 325 if (!(condition)) \ 326 prefix ## suffix(); \ 327 } while (0) 328 #else 329 # define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) 330 #endif 331 332 #define _compiletime_assert(condition, msg, prefix, suffix) \ 333 __compiletime_assert(condition, msg, prefix, suffix) 334 335 /** 336 * compiletime_assert - break build and emit msg if condition is false 337 * @condition: a compile-time constant condition to check 338 * @msg: a message to emit if condition is false 339 * 340 * In tradition of POSIX assert, this macro will break the build if the 341 * supplied condition is *false*, emitting the supplied error message if the 342 * compiler has support to do so. 343 */ 344 #define compiletime_assert(condition, msg) \ 345 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) 346 347 #define compiletime_assert_atomic_type(t) \ 348 compiletime_assert(__native_word(t), \ 349 "Need native word sized stores/loads for atomicity.") 350 351 /* &a[0] degrades to a pointer: a different type from an array */ 352 #define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) 353 354 #endif /* __LINUX_COMPILER_H */ 355