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authorBorislav Petkov <bp@suse.de>2016-01-27 00:12:05 +0300
committerIngo Molnar <mingo@kernel.org>2016-01-30 13:22:18 +0300
commitbc696ca05f5a8927329ec276a892341e006b00ba (patch)
treea8200bfe9677aa30a11b53e8fd6215aaeb3a4a96 /arch/x86/kernel/vm86_32.c
parentcd4d09ec6f6c12a2cc3db5b7d8876a325a53545b (diff)
downloadlinux-bc696ca05f5a8927329ec276a892341e006b00ba.tar.xz
x86/cpufeature: Replace the old static_cpu_has() with safe variant
So the old one didn't work properly before alternatives had run. And it was supposed to provide an optimized JMP because the assumption was that the offset it is jumping to is within a signed byte and thus a two-byte JMP. So I did an x86_64 allyesconfig build and dumped all possible sites where static_cpu_has() was used. The optimization amounted to all in all 12(!) places where static_cpu_has() had generated a 2-byte JMP. Which has saved us a whopping 36 bytes! This clearly is not worth the trouble so we can remove it. The only place where the optimization might count - in __switch_to() - we will handle differently. But that's not subject of this patch. Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> 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/1453842730-28463-6-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/vm86_32.c')
-rw-r--r--arch/x86/kernel/vm86_32.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/vm86_32.c b/arch/x86/kernel/vm86_32.c
index e574b8546518..3dce1ca0a653 100644
--- a/arch/x86/kernel/vm86_32.c
+++ b/arch/x86/kernel/vm86_32.c
@@ -362,7 +362,7 @@ static long do_sys_vm86(struct vm86plus_struct __user *user_vm86, bool plus)
/* make room for real-mode segments */
tsk->thread.sp0 += 16;
- if (static_cpu_has_safe(X86_FEATURE_SEP))
+ if (static_cpu_has(X86_FEATURE_SEP))
tsk->thread.sysenter_cs = 0;
load_sp0(tss, &tsk->thread);