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From: Xin LI <delphij@FreeBSD.org>
Date: Fri, 30 Jul 2010 21:39:28 +0000 (UTC)
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Subject: svn commit: r210665 - head/sys/amd64/amd64
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Author: delphij
Date: Fri Jul 30 21:39:28 2010
New Revision: 210665
URL: http://svn.freebsd.org/changeset/base/210665

Log:
  In rdmsr_safe, use zero extend (by doing a 32-bit movl over
  eax to itself) instead of a sign extend.
  
  Discussed with:	stas
  MFC after:	1 month

Modified:
  head/sys/amd64/amd64/support.S

Modified: head/sys/amd64/amd64/support.S
==============================================================================
--- head/sys/amd64/amd64/support.S	Fri Jul 30 21:28:25 2010	(r210664)
+++ head/sys/amd64/amd64/support.S	Fri Jul 30 21:39:28 2010	(r210665)
@@ -729,7 +729,7 @@ ENTRY(rdmsr_safe)
 	rdmsr			/* Read MSR pointed by %ecx. Returns
 				   hi byte in edx, lo in %eax */
 	salq	$32,%rdx	/* sign-shift %rdx left */
-	cltq			/* sign-extend %eax -> %rax */
+	movl	%eax,%eax	/* zero-extend %eax -> %rax */
 	orq	%rdx,%rax
 	movq	%rax,(%rsi)
 	xorq	%rax,%rax