linux-kernel - [tip:x86/urgent] x86: kernel_thread() -- initialize SS to a known state

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Message-ID: <tip-864a0922dd128392467611d9857e5138c6a91999@git.kernel.org>
Date:	Wed, 13 Jan 2010 16:39:35 GMT
From:	tip-bot for Cyrill Gorcunov <gorcunov@...nvz.org>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	gorcunov@...nvz.org, brgerst@...il.com, ian.campbell@...rix.com,
	lists@...dbynature.de, Jeremy.Fitzhardinge@...rix.com,
	tglx@...utronix.de, mingo@...e.hu
Subject: [tip:x86/urgent] x86: kernel_thread() -- initialize SS to a known state

Commit-ID:  864a0922dd128392467611d9857e5138c6a91999
Gitweb:     http://git.kernel.org/tip/864a0922dd128392467611d9857e5138c6a91999
Author:     Cyrill Gorcunov <gorcunov@...nvz.org>
AuthorDate: Wed, 13 Jan 2010 10:16:07 +0000
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Wed, 13 Jan 2010 11:23:45 +0100

x86: kernel_thread() -- initialize SS to a known state

Before the kernel_thread was converted into "C" we had
pt_regs::ss set to __KERNEL_DS (by SAVE_ALL asm macro).

Though I must admit I didn't find any *explicit* load of
%ss from this structure the better to be on a safe side
and set it to a known value.

Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org>
Signed-off-by: Ian Campbell <ian.campbell@...rix.com>
Cc: Christian Kujau <lists@...dbynature.de>
Cc: Jeremy Fitzhardinge <Jeremy.Fitzhardinge@...rix.com>
Cc: Brian Gerst <brgerst@...il.com>
LKML-Reference: <1263377768-19600-1-git-send-email-ian.campbell@...rix.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/kernel/process.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index c6ee241..02c3ee0 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -288,6 +288,8 @@ int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 	regs.es = __USER_DS;
 	regs.fs = __KERNEL_PERCPU;
 	regs.gs = __KERNEL_STACK_CANARY;
+#else
+	regs.ss = __KERNEL_DS;
 #endif
 
 	regs.orig_ax = -1;
--
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