linux-kernel - [tip:x86/asm] x86-32: Avoid pipeline serialization in PTREGSCALL1 and 2

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Message-ID: <tip-ce9119ad90b1caba550447bfcc0a21850558ca49@git.kernel.org>
Date:	Thu, 10 Dec 2009 00:47:12 GMT
From:	"tip-bot for H. Peter Anvin" <hpa@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	brgerst@...il.com, tglx@...utronix.de
Subject: [tip:x86/asm] x86-32: Avoid pipeline serialization in PTREGSCALL1 and 2

Commit-ID:  ce9119ad90b1caba550447bfcc0a21850558ca49
Gitweb:     http://git.kernel.org/tip/ce9119ad90b1caba550447bfcc0a21850558ca49
Author:     H. Peter Anvin <hpa@...or.com>
AuthorDate: Wed, 9 Dec 2009 16:33:44 -0800
Committer:  H. Peter Anvin <hpa@...or.com>
CommitDate: Wed, 9 Dec 2009 16:33:44 -0800

x86-32: Avoid pipeline serialization in PTREGSCALL1 and 2

In the PTREGSCALL1 and 2 macros, we can trivially avoid an unnecessary
pipeline serialization, so do so.

In PTREGSCALLS3 this is much less clear-cut since we have to push a
new value to the stack.  Leave it alone for now assuming it is as good
as it is going to be; may want to check on Atom or another in-order
x86 to see if we can do better.

Signed-off-by: H. Peter Anvin <hpa@...or.com>
Cc: Brian Gerst <brgerst@...il.com>
LKML-Reference: <1260403316-5679-2-git-send-email-brgerst@...il.com>
---
 arch/x86/kernel/entry_32.S |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 6492555..cb12b9b 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -735,15 +735,15 @@ ptregs_##name: \
 	ALIGN; \
 ptregs_##name: \
 	leal 4(%esp),%edx; \
-	movl PT_EBX(%edx),%eax; \
+	movl (PT_EBX+4)(%esp),%eax; \
 	jmp sys_##name;
 
 #define PTREGSCALL2(name) \
 	ALIGN; \
 ptregs_##name: \
 	leal 4(%esp),%ecx; \
-	movl PT_ECX(%ecx),%edx; \
-	movl PT_EBX(%ecx),%eax; \
+	movl (PT_ECX+4)(%esp),%edx; \
+	movl (PT_EBX+4)(%esp),%eax; \
 	jmp sys_##name;
 
 #define PTREGSCALL3(name) \
--
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