Commit-ID: f2cc8e0791c70833758101d9756609a08dd601ec
Gitweb: http://git.kernel.org/tip/f2cc8e0791c70833758101d9756609a08dd601ec
Author: Borislav Petkov <b...@suse.de>
AuthorDate: Tue, 16 Feb 2016 00:19:18 +0100
Committer: Ingo Molnar <mi...@kernel.org>
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 <b...@suse.de>
Cc: Joerg Roedel <j...@8bytes.org>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Link: http://lkml.kernel.org/r/1455578358-28347-1-git-send-email...@alien8.de
Signed-off-by: Ingo Molnar <mi...@kernel.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 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)
