linux-kernel - [PATCH 89/91] i8k: Avoid lahf in 64-bit code

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Message-Id: <20120205220953.271302918@pcw.home.local>
Date:	Sun, 05 Feb 2012 23:11:18 +0100
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Luca Tettamanti <kronos.it@...il.com>,
	Massimo Dal Zotto <dz@...ian.org>,
	Jean Delvare <khali@...ux-fr.org>,
	Greg KH <gregkh@...uxfoundation.org>
Subject: [PATCH 89/91] i8k: Avoid lahf in 64-bit code

2.6.27-longterm review patch.  If anyone has any objections, please let us know.

------------------

commit bc1f419c76a2d6450413ce4349f4e4a07be011d5 upstream.

i8k uses lahf to read the flag register in 64-bit code; early x86-64
CPUs, however, lack this instruction and we get an invalid opcode
exception at runtime.
Use pushf to load the flag register into the stack instead.

Signed-off-by: Luca Tettamanti <kronos.it@...il.com>
Reported-by: Jeff Rickman <jrickman@...migos.us>
Tested-by: Jeff Rickman <jrickman@...migos.us>
Tested-by: Harry G McGavran Jr <w5pny@...l.net>
Cc: Massimo Dal Zotto <dz@...ian.org>
Signed-off-by: Jean Delvare <khali@...ux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 drivers/char/i8k.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

Index: longterm-2.6.27/drivers/char/i8k.c
===================================================================
--- longterm-2.6.27.orig/drivers/char/i8k.c	2012-02-05 22:34:47.136914619 +0100
+++ longterm-2.6.27/drivers/char/i8k.c	2012-02-05 22:34:47.574914836 +0100
@@ -138,8 +138,8 @@
 		"movl %%edi,20(%%rax)\n\t"
 		"popq %%rdx\n\t"
 		"movl %%edx,0(%%rax)\n\t"
-		"lahf\n\t"
-		"shrl $8,%%eax\n\t"
+		"pushfq\n\t"
+		"popq %%rax\n\t"
 		"andl $1,%%eax\n"
 		:"=a"(rc)
 		:    "a"(regs)


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