1/* SPDX-License-Identifier: GPL-2.0 */ 2#ifndef _TOOLS_LINUX_COMPILER_H_ 3#define _TOOLS_LINUX_COMPILER_H_ 4 5#include <linux/compiler_types.h> 6 7#ifndef __compiletime_error 8# define __compiletime_error(message) 9#endif 10 11#ifdef __OPTIMIZE__ 12# define __compiletime_assert(condition, msg, prefix, suffix) \ 13 do { \ 14 extern void prefix ## suffix(void) __compiletime_error(msg); \ 15 if (!(condition)) \ 16 prefix ## suffix(); \ 17 } while (0) 18#else 19# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) 20#endif 21 22#define _compiletime_assert(condition, msg, prefix, suffix) \ 23 __compiletime_assert(condition, msg, prefix, suffix) 24 25/** 26 * compiletime_assert - break build and emit msg if condition is false 27 * @condition: a compile-time constant condition to check 28 * @msg: a message to emit if condition is false 29 * 30 * In tradition of POSIX assert, this macro will break the build if the 31 * supplied condition is *false*, emitting the supplied error message if the 32 * compiler has support to do so. 33 */ 34#define compiletime_assert(condition, msg) \ 35 _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) 36 37/* Optimization barrier */ 38/* The "volatile" is due to gcc bugs */ 39#define barrier() __asm__ __volatile__("": : :"memory") 40 41#ifndef __always_inline 42# define __always_inline inline __attribute__((always_inline)) 43#endif 44 45#ifndef __always_unused 46#define __always_unused __attribute__((__unused__)) 47#endif 48 49#ifndef __noreturn 50#define __noreturn __attribute__((__noreturn__)) 51#endif 52 53#ifndef unreachable 54#define unreachable() __builtin_unreachable() 55#endif 56 57#ifndef noinline 58#define noinline 59#endif 60 61/* Are two types/vars the same type (ignoring qualifiers)? */ 62#ifndef __same_type 63# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) 64#endif 65 66/* 67 * This returns a constant expression while determining if an argument is 68 * a constant expression, most importantly without evaluating the argument. 69 * Glory to Martin Uecker <Martin.Uecker@med.uni-goettingen.de> 70 */ 71#define __is_constexpr(x) \ 72 (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8))) 73 74#ifdef __ANDROID__ 75/* 76 * FIXME: Big hammer to get rid of tons of: 77 * "warning: always_inline function might not be inlinable" 78 * 79 * At least on android-ndk-r12/platforms/android-24/arch-arm 80 */ 81#undef __always_inline 82#define __always_inline inline 83#endif 84 85#define __user 86#define __rcu 87#define __read_mostly 88 89#ifndef __attribute_const__ 90# define __attribute_const__ 91#endif 92 93#ifndef __maybe_unused 94# define __maybe_unused __attribute__((unused)) 95#endif 96 97#ifndef __used 98# define __used __attribute__((__unused__)) 99#endif 100 101#ifndef __packed 102# define __packed __attribute__((__packed__)) 103#endif 104 105#ifndef __force 106# define __force 107#endif 108 109#ifndef __weak 110# define __weak __attribute__((weak)) 111#endif 112 113#ifndef likely 114# define likely(x) __builtin_expect(!!(x), 1) 115#endif 116 117#ifndef unlikely 118# define unlikely(x) __builtin_expect(!!(x), 0) 119#endif 120 121#ifndef __init 122# define __init 123#endif 124 125#include <linux/types.h> 126 127/* 128 * Following functions are taken from kernel sources and 129 * break aliasing rules in their original form. 130 * 131 * While kernel is compiled with -fno-strict-aliasing, 132 * perf uses -Wstrict-aliasing=3 which makes build fail 133 * under gcc 4.4. 134 * 135 * Using extra __may_alias__ type to allow aliasing 136 * in this case. 137 */ 138typedef __u8 __attribute__((__may_alias__)) __u8_alias_t; 139typedef __u16 __attribute__((__may_alias__)) __u16_alias_t; 140typedef __u32 __attribute__((__may_alias__)) __u32_alias_t; 141typedef __u64 __attribute__((__may_alias__)) __u64_alias_t; 142 143static __always_inline void __read_once_size(const volatile void *p, void *res, int size) 144{ 145 switch (size) { 146 case 1: *(__u8_alias_t *) res = *(volatile __u8_alias_t *) p; break; 147 case 2: *(__u16_alias_t *) res = *(volatile __u16_alias_t *) p; break; 148 case 4: *(__u32_alias_t *) res = *(volatile __u32_alias_t *) p; break; 149 case 8: *(__u64_alias_t *) res = *(volatile __u64_alias_t *) p; break; 150 default: 151 barrier(); 152 __builtin_memcpy((void *)res, (const void *)p, size); 153 barrier(); 154 } 155} 156 157static __always_inline void __write_once_size(volatile void *p, void *res, int size) 158{ 159 switch (size) { 160 case 1: *(volatile __u8_alias_t *) p = *(__u8_alias_t *) res; break; 161 case 2: *(volatile __u16_alias_t *) p = *(__u16_alias_t *) res; break; 162 case 4: *(volatile __u32_alias_t *) p = *(__u32_alias_t *) res; break; 163 case 8: *(volatile __u64_alias_t *) p = *(__u64_alias_t *) res; break; 164 default: 165 barrier(); 166 __builtin_memcpy((void *)p, (const void *)res, size); 167 barrier(); 168 } 169} 170 171/* 172 * Prevent the compiler from merging or refetching reads or writes. The 173 * compiler is also forbidden from reordering successive instances of 174 * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some 175 * particular ordering. One way to make the compiler aware of ordering is to 176 * put the two invocations of READ_ONCE or WRITE_ONCE in different C 177 * statements. 178 * 179 * These two macros will also work on aggregate data types like structs or 180 * unions. If the size of the accessed data type exceeds the word size of 181 * the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will 182 * fall back to memcpy and print a compile-time warning. 183 * 184 * Their two major use cases are: (1) Mediating communication between 185 * process-level code and irq/NMI handlers, all running on the same CPU, 186 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise 187 * mutilate accesses that either do not require ordering or that interact 188 * with an explicit memory barrier or atomic instruction that provides the 189 * required ordering. 190 */ 191 192#define READ_ONCE(x) \ 193({ \ 194 union { typeof(x) __val; char __c[1]; } __u = \ 195 { .__c = { 0 } }; \ 196 __read_once_size(&(x), __u.__c, sizeof(x)); \ 197 __u.__val; \ 198}) 199 200#define WRITE_ONCE(x, val) \ 201({ \ 202 union { typeof(x) __val; char __c[1]; } __u = \ 203 { .__val = (val) }; \ 204 __write_once_size(&(x), __u.__c, sizeof(x)); \ 205 __u.__val; \ 206}) 207 208 209/* Indirect macros required for expanded argument pasting, eg. __LINE__. */ 210#define ___PASTE(a, b) a##b 211#define __PASTE(a, b) ___PASTE(a, b) 212 213#ifndef OPTIMIZER_HIDE_VAR 214/* Make the optimizer believe the variable can be manipulated arbitrarily. */ 215#define OPTIMIZER_HIDE_VAR(var) \ 216 __asm__ ("" : "=r" (var) : "0" (var)) 217#endif 218 219#endif /* _TOOLS_LINUX_COMPILER_H */ 220