linux-kernel - [tip:x86/cleanups] x86_64: Use __BOOT_DS instead_of __KERNEL

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Message-ID: <tip-b317219b322e36e25150d7b64f4532401779959d@git.kernel.org>
Date:	Thu, 28 Feb 2013 21:23:40 -0800
From:	tip-bot for gmail <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, lans.zhang2008@...il.com,
	hpa@...or.com, mingo@...nel.org, tglx@...utronix.de,
	hpa@...ux.intel.com
Subject: [tip:x86/cleanups] x86_64:
  Use __BOOT_DS instead_of __KERNEL_DS for safety

Commit-ID:  b317219b322e36e25150d7b64f4532401779959d
Gitweb:     http://git.kernel.org/tip/b317219b322e36e25150d7b64f4532401779959d
Author:     gmail <lans.zhang2008@...il.com>
AuthorDate: Fri, 1 Mar 2013 09:20:39 +0800
Committer:  H. Peter Anvin <hpa@...ux.intel.com>
CommitDate: Thu, 28 Feb 2013 20:19:50 -0800

x86_64: Use __BOOT_DS instead_of __KERNEL_DS for safety

In startup_32, the running code still uses the initial GDT
located in setup. Thus, __BOOT_DS is preferred. Currently
__KERNEL_DS is lucky to equal to __BOOT_DS, but this is
not always a safe way.

Signed-off-by: Lans Zhang <lans.zhang2008@...il.com>
Link: http://lkml.kernel.org/r/51300267.6000008@gmail.com
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
---
 arch/x86/boot/compressed/head_64.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index c1d383d..16f24e6 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -52,7 +52,7 @@ ENTRY(startup_32)
 	jnz 1f
 
 	cli
-	movl	$(__KERNEL_DS), %eax
+	movl	$(__BOOT_DS), %eax
 	movl	%eax, %ds
 	movl	%eax, %es
 	movl	%eax, %ss
--
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