brgerst at gmail
Nov 25, 2009, 11:18 AM
Post #1 of 1
(88 views)
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[PATCH] x86: loadsegment() optimization
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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 [at] gmail>
---
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 f08f973..18ac1ec 100644
--- a/arch/x86/include/asm/system.h
+++ b/arch/x86/include/asm/system.h
@@ -158,18 +158,19 @@ 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
--
1.6.5.2
--
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