130 lines
4.0 KiB
C
130 lines
4.0 KiB
C
#ifndef _TOOLS_LINUX_COMPILER_H_
|
|
#define _TOOLS_LINUX_COMPILER_H_
|
|
|
|
/* 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
|
|
|
|
#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
|
|
|
|
#ifndef __attribute_const__
|
|
# define __attribute_const__
|
|
#endif
|
|
|
|
#ifndef __maybe_unused
|
|
# define __maybe_unused __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
|
|
|
|
#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
|
|
|
|
#include <linux/types.h>
|
|
|
|
/*
|
|
* 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, WRITE_ONCE and ACCESS_ONCE (see below), 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,
|
|
* WRITE_ONCE or ACCESS_ONCE() in different C statements.
|
|
*
|
|
* In contrast to ACCESS_ONCE 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; __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; })
|
|
|
|
#endif /* _TOOLS_LINUX_COMPILER_H */
|