diff options
Diffstat (limited to 'arch/arc')
| -rw-r--r-- | arch/arc/include/asm/io.h | 30 |
1 files changed, 19 insertions, 11 deletions
diff --git a/arch/arc/include/asm/io.h b/arch/arc/include/asm/io.h index 1f1ae889f3..a4171a3e5c 100644 --- a/arch/arc/include/asm/io.h +++ b/arch/arc/include/asm/io.h @@ -9,6 +9,12 @@ #include <linux/types.h> #include <asm/byteorder.h> +/* + * Compiler barrier. It prevents compiler from reordering instructions before + * and after it. It doesn't prevent HW (CPU) from any reordering though. + */ +#define __comp_b() asm volatile("" : : : "memory") + #ifdef __ARCHS__ /* @@ -45,8 +51,8 @@ #define __iormb() rmb() #define __iowmb() wmb() #else -#define __iormb() asm volatile("" : : : "memory") -#define __iowmb() asm volatile("" : : : "memory") +#define __iormb() __comp_b() +#define __iowmb() __comp_b() #endif static inline void sync(void) @@ -58,16 +64,18 @@ static inline void sync(void) * We must use 'volatile' in C-version read/write IO accessors implementation * to avoid merging several reads (writes) into one read (write), or optimizing * them out by compiler. + * We must use compiler barriers before and after operation (read or write) so + * it won't be reordered by compiler. */ -#define __arch_getb(a) (*(volatile u8 *)(a)) -#define __arch_getw(a) (*(volatile u16 *)(a)) -#define __arch_getl(a) (*(volatile u32 *)(a)) -#define __arch_getq(a) (*(volatile u64 *)(a)) - -#define __arch_putb(v, a) (*(volatile u8 *)(a) = (v)) -#define __arch_putw(v, a) (*(volatile u16 *)(a) = (v)) -#define __arch_putl(v, a) (*(volatile u32 *)(a) = (v)) -#define __arch_putq(v, a) (*(volatile u64 *)(a) = (v)) +#define __arch_getb(a) ({ u8 __v; __comp_b(); __v = *(volatile u8 *)(a); __comp_b(); __v; }) +#define __arch_getw(a) ({ u16 __v; __comp_b(); __v = *(volatile u16 *)(a); __comp_b(); __v; }) +#define __arch_getl(a) ({ u32 __v; __comp_b(); __v = *(volatile u32 *)(a); __comp_b(); __v; }) +#define __arch_getq(a) ({ u64 __v; __comp_b(); __v = *(volatile u64 *)(a); __comp_b(); __v; }) + +#define __arch_putb(v, a) ({ __comp_b(); *(volatile u8 *)(a) = (v); __comp_b(); }) +#define __arch_putw(v, a) ({ __comp_b(); *(volatile u16 *)(a) = (v); __comp_b(); }) +#define __arch_putl(v, a) ({ __comp_b(); *(volatile u32 *)(a) = (v); __comp_b(); }) +#define __arch_putq(v, a) ({ __comp_b(); *(volatile u64 *)(a) = (v); __comp_b(); }) #define __raw_writeb(v, a) __arch_putb(v, a) |