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| author |   Brian Gerst <brgerst@gmail.com> | 2009-11-25 14:18:26 -0500 |
|---|---|---|
| committer |   Ingo Molnar <mingo@elte.hu> | 2009-11-26 10:33:58 +0100 |
| commit | 79b0379cee09b00ef309384aff652e328e438c79 (patch) | |
| tree | 5a87d096d1f05b47f8372eda2523b1e1c830be23 /arch/x86/include/asm/system.h | |
| parent | x86: Add missing might_fault() checks to copy_{to,from}_user() (diff) | |
| download | linux-dev-79b0379cee09b00ef309384aff652e328e438c79.tar.xz linux-dev-79b0379cee09b00ef309384aff652e328e438c79.zip | |
x86: Optimize loadsegment()
Zero the input register in the exception handler instead of
using an extra register to pass in a zero value.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1259176706-5908-1-git-send-email-brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/include/asm/system.h')
| -rw-r--r-- | arch/x86/include/asm/system.h | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h index 1a953e26401c..537395a2877a 100644 --- a/arch/x86/include/asm/system.h +++ b/arch/x86/include/asm/system.h @@ -156,18 +156,19 @@ extern void native_load_gs_index(unsigned); * segment if something goes wrong.. */ #define loadsegment(seg, value) \ +do { \ + unsigned short __val = value; \ asm volatile("\n" \ "1:\t" \ "movl %k0,%%" #seg "\n" \ - "2:\n" \ ".section .fixup,\"ax\"\n" \ - "3:\t" \ - "movl %k1, %%" #seg "\n\t" \ - "jmp 2b\n" \ + "2:\t" \ + "xorl %k0,%k0\n\t" \ + "jmp 1b\n" \ ".previous\n" \ - _ASM_EXTABLE(1b,3b) \ - : :"r" (value), "r" (0) : "memory") - + _ASM_EXTABLE(1b, 2b) \ + : "+r" (__val) : : "memory"); \ +} while (0) /* * Save a segment register away |