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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef _TOOLS_LINUX_COMPILER_H_3#define _TOOLS_LINUX_COMPILER_H_4 5#ifndef __ASSEMBLY__6 7#include <linux/compiler_types.h>8 9#ifndef __compiletime_error10# define __compiletime_error(message)11#endif12 13#ifdef __OPTIMIZE__14# define __compiletime_assert(condition, msg, prefix, suffix) \15 do { \16 extern void prefix ## suffix(void) __compiletime_error(msg); \17 if (!(condition)) \18 prefix ## suffix(); \19 } while (0)20#else21# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)22#endif23 24#define _compiletime_assert(condition, msg, prefix, suffix) \25 __compiletime_assert(condition, msg, prefix, suffix)26 27/**28 * compiletime_assert - break build and emit msg if condition is false29 * @condition: a compile-time constant condition to check30 * @msg: a message to emit if condition is false31 *32 * In tradition of POSIX assert, this macro will break the build if the33 * supplied condition is *false*, emitting the supplied error message if the34 * compiler has support to do so.35 */36#define compiletime_assert(condition, msg) \37 _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)38 39/* Optimization barrier */40/* The "volatile" is due to gcc bugs */41#define barrier() __asm__ __volatile__("": : :"memory")42 43#ifndef __always_inline44# define __always_inline inline __attribute__((always_inline))45#endif46 47#ifndef __always_unused48#define __always_unused __attribute__((__unused__))49#endif50 51#ifndef __noreturn52#define __noreturn __attribute__((__noreturn__))53#endif54 55#ifndef unreachable56#define unreachable() __builtin_unreachable()57#endif58 59#ifndef noinline60#define noinline61#endif62 63#ifndef __nocf_check64#define __nocf_check __attribute__((nocf_check))65#endif66 67#ifndef __naked68#define __naked __attribute__((__naked__))69#endif70 71/* Are two types/vars the same type (ignoring qualifiers)? */72#ifndef __same_type73# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))74#endif75 76/*77 * This returns a constant expression while determining if an argument is78 * a constant expression, most importantly without evaluating the argument.79 * Glory to Martin Uecker <Martin.Uecker@med.uni-goettingen.de>80 */81#define __is_constexpr(x) \82 (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))83 84#ifdef __ANDROID__85/*86 * FIXME: Big hammer to get rid of tons of:87 * "warning: always_inline function might not be inlinable"88 *89 * At least on android-ndk-r12/platforms/android-24/arch-arm90 */91#undef __always_inline92#define __always_inline inline93#endif94 95#define __user96#define __rcu97#define __read_mostly98 99#ifndef __attribute_const__100# define __attribute_const__101#endif102 103#ifndef __maybe_unused104# define __maybe_unused __attribute__((unused))105#endif106 107#ifndef __used108# define __used __attribute__((__unused__))109#endif110 111#ifndef __packed112# define __packed __attribute__((__packed__))113#endif114 115#ifndef __force116# define __force117#endif118 119#ifndef __weak120# define __weak __attribute__((weak))121#endif122 123#ifndef likely124# define likely(x) __builtin_expect(!!(x), 1)125#endif126 127#ifndef unlikely128# define unlikely(x) __builtin_expect(!!(x), 0)129#endif130 131#include <linux/types.h>132 133/*134 * Following functions are taken from kernel sources and135 * break aliasing rules in their original form.136 *137 * While kernel is compiled with -fno-strict-aliasing,138 * perf uses -Wstrict-aliasing=3 which makes build fail139 * under gcc 4.4.140 *141 * Using extra __may_alias__ type to allow aliasing142 * in this case.143 */144typedef __u8 __attribute__((__may_alias__)) __u8_alias_t;145typedef __u16 __attribute__((__may_alias__)) __u16_alias_t;146typedef __u32 __attribute__((__may_alias__)) __u32_alias_t;147typedef __u64 __attribute__((__may_alias__)) __u64_alias_t;148 149static __always_inline void __read_once_size(const volatile void *p, void *res, int size)150{151 switch (size) {152 case 1: *(__u8_alias_t *) res = *(volatile __u8_alias_t *) p; break;153 case 2: *(__u16_alias_t *) res = *(volatile __u16_alias_t *) p; break;154 case 4: *(__u32_alias_t *) res = *(volatile __u32_alias_t *) p; break;155 case 8: *(__u64_alias_t *) res = *(volatile __u64_alias_t *) p; break;156 default:157 barrier();158 __builtin_memcpy((void *)res, (const void *)p, size);159 barrier();160 }161}162 163static __always_inline void __write_once_size(volatile void *p, void *res, int size)164{165 switch (size) {166 case 1: *(volatile __u8_alias_t *) p = *(__u8_alias_t *) res; break;167 case 2: *(volatile __u16_alias_t *) p = *(__u16_alias_t *) res; break;168 case 4: *(volatile __u32_alias_t *) p = *(__u32_alias_t *) res; break;169 case 8: *(volatile __u64_alias_t *) p = *(__u64_alias_t *) res; break;170 default:171 barrier();172 __builtin_memcpy((void *)p, (const void *)res, size);173 barrier();174 }175}176 177/*178 * Prevent the compiler from merging or refetching reads or writes. The179 * compiler is also forbidden from reordering successive instances of180 * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some181 * particular ordering. One way to make the compiler aware of ordering is to182 * put the two invocations of READ_ONCE or WRITE_ONCE in different C183 * statements.184 *185 * These two macros will also work on aggregate data types like structs or186 * unions. If the size of the accessed data type exceeds the word size of187 * the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will188 * fall back to memcpy and print a compile-time warning.189 *190 * Their two major use cases are: (1) Mediating communication between191 * process-level code and irq/NMI handlers, all running on the same CPU,192 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise193 * mutilate accesses that either do not require ordering or that interact194 * with an explicit memory barrier or atomic instruction that provides the195 * required ordering.196 */197 198#define READ_ONCE(x) \199({ \200 union { typeof(x) __val; char __c[1]; } __u = \201 { .__c = { 0 } }; \202 __read_once_size(&(x), __u.__c, sizeof(x)); \203 __u.__val; \204})205 206#define WRITE_ONCE(x, val) \207({ \208 union { typeof(x) __val; char __c[1]; } __u = \209 { .__val = (val) }; \210 __write_once_size(&(x), __u.__c, sizeof(x)); \211 __u.__val; \212})213 214 215/* Indirect macros required for expanded argument pasting, eg. __LINE__. */216#define ___PASTE(a, b) a##b217#define __PASTE(a, b) ___PASTE(a, b)218 219#ifndef OPTIMIZER_HIDE_VAR220/* Make the optimizer believe the variable can be manipulated arbitrarily. */221#define OPTIMIZER_HIDE_VAR(var) \222 __asm__ ("" : "=r" (var) : "0" (var))223#endif224 225#endif /* __ASSEMBLY__ */226 227#endif /* _TOOLS_LINUX_COMPILER_H */228