[PATCH] x86: loadsegment() optimization

[PATCH] x86: loadsegment() optimization

[Brian Gerst]

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>
---
 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

[tip:x86/asm] x86: Optimize loadsegment()

[tip-bot for Brian Gerst]

Commit-ID:  79b0379cee09b00ef309384aff652e328e438c79
Gitweb:     http://git.kernel.org/tip/79b0379cee09b00ef309384aff652e328e438c79
Author:     Brian Gerst <brgerst@gmail.com>
AuthorDate: Wed, 25 Nov 2009 14:18:26 -0500
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 26 Nov 2009 10:33:58 +0100

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>
---
 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 1a953e2..537395a 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

[tip:x86/asm] x86: Clean up the loadsegment() macro

[tip-bot for Ingo Molnar]

Commit-ID:  64b028b22616946a05bf9580f7f7f7ee2ac070b4
Gitweb:     http://git.kernel.org/tip/64b028b22616946a05bf9580f7f7f7ee2ac070b4
Author:     Ingo Molnar <mingo@elte.hu>
AuthorDate: Thu, 26 Nov 2009 10:37:55 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 26 Nov 2009 10:38:52 +0100

x86: Clean up the loadsegment() macro

Make it readable in the source too, not just in the assembly output.
No change in functionality.

Cc: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1259176706-5908-1-git-send-email-brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/include/asm/system.h |   28 +++++++++++++++-------------
 1 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
index 537395a..022a843 100644
--- a/arch/x86/include/asm/system.h
+++ b/arch/x86/include/asm/system.h
@@ -155,19 +155,21 @@ extern void native_load_gs_index(unsigned);
  * Load a segment. Fall back on loading the zero
  * segment if something goes wrong..
  */
-#define loadsegment(seg, value)			\
-do {						\
-	unsigned short __val = value;		\
-	asm volatile("\n"			\
-		     "1:\t"			\
-		     "movl %k0,%%" #seg "\n"	\
-		     ".section .fixup,\"ax\"\n"	\
-		     "2:\t"			\
-		     "xorl %k0,%k0\n\t"		\
-		     "jmp 1b\n"			\
-		     ".previous\n"		\
-		     _ASM_EXTABLE(1b, 2b)	\
-		     : "+r" (__val) : : "memory"); \
+#define loadsegment(seg, value)						\
+do {									\
+	unsigned short __val = (value);					\
+									\
+	asm volatile("						\n"	\
+		     "1:	movl %k0,%%" #seg "		\n"	\
+									\
+		     ".section .fixup,\"ax\"			\n"	\
+		     "2:	xorl %k0,%k0			\n"	\
+		     "		jmp 1b				\n"	\
+		     ".previous					\n"	\
+									\
+		     _ASM_EXTABLE(1b, 2b)				\
+									\
+		     : "+r" (__val) : : "memory");			\
 } while (0)
 
 /*