linux-kernel - [PATCH] x86: kernel_thread -- initialize SS to a known state

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Message-Id: <1263377768-19600-1-git-send-email-ian.campbell@citrix.com>
Date:	Wed, 13 Jan 2010 10:16:07 +0000
From:	Ian Campbell <ian.campbell@...rix.com>
To:	x86@...nel.org, linux-kernel@...r.kernel.org
Cc:	Christian Kujau <lists@...dbynature.de>,
	Jeremy Fitzhardinge <Jeremy.Fitzhardinge@...rix.com>,
	Cyrill Gorcunov <gorcunov@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>, Brian Gerst <brgerst@...il.com>,
	Cyrill Gorcunov <gorcunov@...nvz.org>,
	Ian Campbell <ian.campbell@...rix.com>
Subject: [PATCH] x86: kernel_thread -- initialize SS to a known state

From: Cyrill Gorcunov <gorcunov@...nvz.org>

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>
---
 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;
-- 
1.5.6.5

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