linux-kernel - [128/146] i8k: Avoid lahf in 64-bit code

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Message-Id: <20110601080445.810442485@blue.kroah.org>
Date:	Wed, 01 Jun 2011 17:01:04 +0900
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Luca Tettamanti <kronos.it@...il.com>,
	Massimo Dal Zotto <dz@...ian.org>,
	Jean Delvare <khali@...ux-fr.org>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: [128/146] i8k: Avoid lahf in 64-bit code

2.6.38-stable review patch.  If anyone has any objections, please let us know.

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

From: Luca Tettamanti <kronos.it@...il.com>

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 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/char/i8k.c
+++ b/drivers/char/i8k.c
@@ -139,8 +139,8 @@ static int i8k_smm(struct smm_regs *regs
 		"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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