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Commit 79b0379c authored by Brian Gerst's avatar Brian Gerst Committed by Ingo Molnar
Browse files

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: default avatarBrian Gerst <brgerst@gmail.com>
LKML-Reference: <1259176706-5908-1-git-send-email-brgerst@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 3c93ca00

arch/x86/include/asm/system.h

+8 −7
Original line number Diff line number Diff line
@@ -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