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