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__) 17void 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 <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 196static __always_inline 197void __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 214static __no_kasan_or_inline 215void __read_once_size_nocheck(const volatile void *p, void *res, int size) 216{ 217 __READ_ONCE_SIZE; 218} 219 220static __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 */ 256 257#define __READ_ONCE(x, check) \ 258({ \ 259 union { typeof(x) __val; char __c[1]; } __u; \ 260 if (check) \ 261 __read_once_size(&(x), __u.__c, sizeof(x)); \ 262 else \ 263 __read_once_size_nocheck(&(x), __u.__c, sizeof(x)); \ 264 __u.__val; \ 265}) 266#define READ_ONCE(x) __READ_ONCE(x, 1) 267 268/* 269 * Use READ_ONCE_NOCHECK() instead of READ_ONCE() if you need 270 * to hide memory access from KASAN. 271 */ 272#define READ_ONCE_NOCHECK(x) __READ_ONCE(x, 0) 273 274static __no_kasan_or_inline 275unsigned long read_word_at_a_time(const void *addr) 276{ 277 return *(unsigned long *)addr; 278} 279 280#define WRITE_ONCE(x, val) \ 281({ \ 282 union { typeof(x) __val; char __c[1]; } __u = \ 283 { .__val = (__force typeof(x)) (val) }; \ 284 __write_once_size(&(x), __u.__c, sizeof(x)); \ 285 __u.__val; \ 286}) 287 288#endif /* __KERNEL__ */ 289 290/* 291 * Force the compiler to emit 'sym' as a symbol, so that we can reference 292 * it from inline assembler. Necessary in case 'sym' could be inlined 293 * otherwise, or eliminated entirely due to lack of references that are 294 * visible to the compiler. 295 */ 296#define __ADDRESSABLE(sym) \ 297 static void * __section(".discard.addressable") __used \ 298 __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym; 299 300/** 301 * offset_to_ptr - convert a relative memory offset to an absolute pointer 302 * @off: the address of the 32-bit offset value 303 */ 304static inline void *offset_to_ptr(const int *off) 305{ 306 return (void *)((unsigned long)off + *off); 307} 308 309#endif /* __ASSEMBLY__ */ 310 311/* Compile time object size, -1 for unknown */ 312#ifndef __compiletime_object_size 313# define __compiletime_object_size(obj) -1 314#endif 315#ifndef __compiletime_warning 316# define __compiletime_warning(message) 317#endif 318#ifndef __compiletime_error 319# define __compiletime_error(message) 320#endif 321 322#ifdef __OPTIMIZE__ 323# define __compiletime_assert(condition, msg, prefix, suffix) \ 324 do { \ 325 extern void prefix ## suffix(void) __compiletime_error(msg); \ 326 if (!(condition)) \ 327 prefix ## suffix(); \ 328 } while (0) 329#else 330# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) 331#endif 332 333#define _compiletime_assert(condition, msg, prefix, suffix) \ 334 __compiletime_assert(condition, msg, prefix, suffix) 335 336/** 337 * compiletime_assert - break build and emit msg if condition is false 338 * @condition: a compile-time constant condition to check 339 * @msg: a message to emit if condition is false 340 * 341 * In tradition of POSIX assert, this macro will break the build if the 342 * supplied condition is *false*, emitting the supplied error message if the 343 * compiler has support to do so. 344 */ 345#define compiletime_assert(condition, msg) \ 346 _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) 347 348#define compiletime_assert_atomic_type(t) \ 349 compiletime_assert(__native_word(t), \ 350 "Need native word sized stores/loads for atomicity.") 351 352/* &a[0] degrades to a pointer: a different type from an array */ 353#define __must_be_array(a) BUILD_BUG_ON_ZERO(__same_type((a), &(a)[0])) 354 355#endif /* __LINUX_COMPILER_H */ 356