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x86: Optimize loadsegment()

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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>
This commit is contained in:
Brian Gerst 2009-11-25 14:18:26 -05:00 committed by Ingo Molnar
parent 3c93ca00ee
commit 79b0379cee
1 changed files with 8 additions and 7 deletions
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15
arch/x86/include/asm/system.h
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@ -156,18 +156,19 @@ extern void native_load_gs_index(unsigned);
* segment if something goes wrong.. * segment if something goes wrong..
*/ */
#define loadsegment(seg, value) \ #define loadsegment(seg, value) \
do { \
unsigned short __val = value; \
asm volatile("\n" \ asm volatile("\n" \
"1:\t" \ "1:\t" \
"movl %k0,%%" #seg "\n" \ "movl %k0,%%" #seg "\n" \
"2:\n" \
".section .fixup,\"ax\"\n" \ ".section .fixup,\"ax\"\n" \
"3:\t" \ "2:\t" \
"movl %k1, %%" #seg "\n\t" \ "xorl %k0,%k0\n\t" \
"jmp 2b\n" \ "jmp 1b\n" \
".previous\n" \ ".previous\n" \
_ASM_EXTABLE(1b,3b) \ _ASM_EXTABLE(1b, 2b) \
: :"r" (value), "r" (0) : "memory") : "+r" (__val) : : "memory"); \
} while (0)
/* /*
* Save a segment register away * Save a segment register away