diff options
| author | Borislav Petkov <bp@suse.de> | 2018-07-14 02:27:55 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-07-17 11:31:45 +0200 |
| commit | 21a4ec5918141be219d977952b8fea7c4db2c827 (patch) | |
| tree | 7ad94223af08745f12ff895d3edf16e324612f62 | |
| parent | a1b00d57298f013e5213dee6c1a5aba6766108ca (diff) | |
x86/cpufeature: Speed up cpu_feature_enabled()
commit f2cc8e0791c70833758101d9756609a08dd601ec upstream
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>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1455578358-28347-1-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa@csail.mit.edu>
Reviewed-by: Matt Helsley (VMware) <matt.helsley@gmail.com>
Reviewed-by: Alexey Makhalov <amakhalov@vmware.com>
Reviewed-by: Bo Gan <ganb@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/include/asm/cpufeature.h | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 1c9d6c5d6d8c..03ca602821b2 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) |