Commit-ID: f2cc8e0791c70833758101d9756609a08dd601ec Gitweb: http://git.kernel.org/tip/f2cc8e0791c70833758101d9756609a08dd601ec Author: Borislav Petkov <bp@xxxxxxx> AuthorDate: Tue, 16 Feb 2016 00:19:18 +0100 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitDate: Tue, 16 Feb 2016 08:45:15 +0100 x86/cpufeature: Speed up cpu_feature_enabled() 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@xxxxxxx> Cc: Joerg Roedel <joro@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1455578358-28347-1-git-send-email-bp@xxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> --- 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 9fba7a5..68e4e82 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) -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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