Messages in this thread Patch in this message | | | From | Borislav Petkov <> | Subject | [PATCH] x86/cpufeature: Speedup cpu_feature_enabled() | Date | Tue, 16 Feb 2016 00:19:18 +0100 |
| |
From: Borislav Petkov <bp@suse.de>
When gcc cannot do constant folding for this macro, it falls back to cpu_has(). But static_cpu_has() is optimal and it works at all times now. So use it and speedup the fallback case.
Before we had this:
mov 0x99d674(%rip),%rdx # ffffffff81b0d9f4 <boot_cpu_data+0x34> shr $0x2e,%rdx and $0x1,%edx jne ffffffff811704e9 <do_munmap+0x3f9>
After alternatives patching, it turns into:
jmp 0xffffffff81170390 nopl (%rax) ... callq ffffffff81056e00 <mpx_notify_unmap> ffffffff81170390: mov 0x170(%r12),%rdi
Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Joerg Roedel <joro@8bytes.org> --- arch/x86/include/asm/cpufeature.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 9fba7a5dd24a..68e4e8258b84 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -88,8 +88,7 @@ extern const char * const x86_bug_flags[NBUGINTS*32]; * is not relevant. */ #define cpu_feature_enabled(bit) \ - (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : \ - cpu_has(&boot_cpu_data, bit)) + (__builtin_constant_p(bit) && DISABLED_MASK_BIT_SET(bit) ? 0 : static_cpu_has(bit)) #define boot_cpu_has(bit) cpu_has(&boot_cpu_data, bit) -- 2.3.5
| |