/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _TOOLS_LINUX_COMPILER_H_ #define _TOOLS_LINUX_COMPILER_H_ #ifndef __ASSEMBLY__ #include #ifndef __compiletime_error # define __compiletime_error(message) #endif #ifdef __OPTIMIZE__ # define __compiletime_assert(condition, msg, prefix, suffix) \ do { \ extern void prefix ## suffix(void) __compiletime_error(msg); \ if (!(condition)) \ prefix ## suffix(); \ } while (0) #else # define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0) #endif #define _compiletime_assert(condition, msg, prefix, suffix) \ __compiletime_assert(condition, msg, prefix, suffix) /** * compiletime_assert - break build and emit msg if condition is false * @condition: a compile-time constant condition to check * @msg: a message to emit if condition is false * * In tradition of POSIX assert, this macro will break the build if the * supplied condition is *false*, emitting the supplied error message if the * compiler has support to do so. */ #define compiletime_assert(condition, msg) \ _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) /* Optimization barrier */ /* The "volatile" is due to gcc bugs */ #define barrier() __asm__ __volatile__("": : :"memory") #ifndef __always_inline # define __always_inline inline __attribute__((always_inline)) #endif #ifndef __always_unused #define __always_unused __attribute__((__unused__)) #endif #ifndef __noreturn #define __noreturn __attribute__((__noreturn__)) #endif #ifndef unreachable #define unreachable() __builtin_unreachable() #endif #ifndef noinline #define noinline #endif #ifndef __nocf_check #define __nocf_check __attribute__((nocf_check)) #endif #ifndef __naked #define __naked __attribute__((__naked__)) #endif /* Are two types/vars the same type (ignoring qualifiers)? */ #ifndef __same_type # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) #endif /* * This returns a constant expression while determining if an argument is * a constant expression, most importantly without evaluating the argument. * Glory to Martin Uecker */ #define __is_constexpr(x) \ (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8))) #ifdef __ANDROID__ /* * FIXME: Big hammer to get rid of tons of: * "warning: always_inline function might not be inlinable" * * At least on android-ndk-r12/platforms/android-24/arch-arm */ #undef __always_inline #define __always_inline inline #endif #define __user #define __rcu #define __read_mostly #ifndef __attribute_const__ # define __attribute_const__ #endif #ifndef __maybe_unused # define __maybe_unused __attribute__((unused)) #endif #ifndef __used # define __used __attribute__((__unused__)) #endif #ifndef __packed # define __packed __attribute__((__packed__)) #endif #ifndef __force # define __force #endif #ifndef __weak # define __weak __attribute__((weak)) #endif #ifndef likely # define likely(x) __builtin_expect(!!(x), 1) #endif #ifndef unlikely # define unlikely(x) __builtin_expect(!!(x), 0) #endif #include /* * Following functions are taken from kernel sources and * break aliasing rules in their original form. * * While kernel is compiled with -fno-strict-aliasing, * perf uses -Wstrict-aliasing=3 which makes build fail * under gcc 4.4. * * Using extra __may_alias__ type to allow aliasing * in this case. */ typedef __u8 __attribute__((__may_alias__)) __u8_alias_t; typedef __u16 __attribute__((__may_alias__)) __u16_alias_t; typedef __u32 __attribute__((__may_alias__)) __u32_alias_t; typedef __u64 __attribute__((__may_alias__)) __u64_alias_t; static __always_inline void __read_once_size(const volatile void *p, void *res, int size) { switch (size) { case 1: *(__u8_alias_t *) res = *(volatile __u8_alias_t *) p; break; case 2: *(__u16_alias_t *) res = *(volatile __u16_alias_t *) p; break; case 4: *(__u32_alias_t *) res = *(volatile __u32_alias_t *) p; break; case 8: *(__u64_alias_t *) res = *(volatile __u64_alias_t *) p; break; default: barrier(); __builtin_memcpy((void *)res, (const void *)p, size); barrier(); } } static __always_inline void __write_once_size(volatile void *p, void *res, int size) { switch (size) { case 1: *(volatile __u8_alias_t *) p = *(__u8_alias_t *) res; break; case 2: *(volatile __u16_alias_t *) p = *(__u16_alias_t *) res; break; case 4: *(volatile __u32_alias_t *) p = *(__u32_alias_t *) res; break; case 8: *(volatile __u64_alias_t *) p = *(__u64_alias_t *) res; break; default: barrier(); __builtin_memcpy((void *)p, (const void *)res, size); barrier(); } } /* * Prevent the compiler from merging or refetching reads or writes. The * compiler is also forbidden from reordering successive instances of * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some * particular ordering. One way to make the compiler aware of ordering is to * put the two invocations of READ_ONCE or WRITE_ONCE in different C * statements. * * These two macros will also work on aggregate data types like structs or * unions. If the size of the accessed data type exceeds the word size of * the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will * fall back to memcpy and print a compile-time warning. * * Their two major use cases are: (1) Mediating communication between * process-level code and irq/NMI handlers, all running on the same CPU, * and (2) Ensuring that the compiler does not fold, spindle, or otherwise * mutilate accesses that either do not require ordering or that interact * with an explicit memory barrier or atomic instruction that provides the * required ordering. */ #define READ_ONCE(x) \ ({ \ union { typeof(x) __val; char __c[1]; } __u = \ { .__c = { 0 } }; \ __read_once_size(&(x), __u.__c, sizeof(x)); \ __u.__val; \ }) #define WRITE_ONCE(x, val) \ ({ \ union { typeof(x) __val; char __c[1]; } __u = \ { .__val = (val) }; \ __write_once_size(&(x), __u.__c, sizeof(x)); \ __u.__val; \ }) /* Indirect macros required for expanded argument pasting, eg. __LINE__. */ #define ___PASTE(a, b) a##b #define __PASTE(a, b) ___PASTE(a, b) #ifndef OPTIMIZER_HIDE_VAR /* Make the optimizer believe the variable can be manipulated arbitrarily. */ #define OPTIMIZER_HIDE_VAR(var) \ __asm__ ("" : "=r" (var) : "0" (var)) #endif #endif /* __ASSEMBLY__ */ #endif /* _TOOLS_LINUX_COMPILER_H */