diff options
Diffstat (limited to 'tools/include/linux/compiler.h')
| -rw-r--r-- | tools/include/linux/compiler.h | 32 |
1 files changed, 24 insertions, 8 deletions
diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h index 909808386..fa7208a32 100644 --- a/tools/include/linux/compiler.h +++ b/tools/include/linux/compiler.h @@ -43,13 +43,29 @@ #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 *)res = *(volatile __u8 *)p; break; - case 2: *(__u16 *)res = *(volatile __u16 *)p; break; - case 4: *(__u32 *)res = *(volatile __u32 *)p; break; - case 8: *(__u64 *)res = *(volatile __u64 *)p; break; + 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); @@ -60,10 +76,10 @@ static __always_inline void __read_once_size(const volatile void *p, void *res, static __always_inline void __write_once_size(volatile void *p, void *res, int size) { switch (size) { - case 1: *(volatile __u8 *)p = *(__u8 *)res; break; - case 2: *(volatile __u16 *)p = *(__u16 *)res; break; - case 4: *(volatile __u32 *)p = *(__u32 *)res; break; - case 8: *(volatile __u64 *)p = *(__u64 *)res; break; + 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); |