linux-kernel - Re: 2.6.29 git, resume from ram broken on thinkpad

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Date:	Fri, 3 Apr 2009 19:39:55 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Chris Wright <chrisw@...s-sol.org>
Cc:	Arkadiusz Miskiewicz <a.miskiewicz@...il.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-kernel@...r.kernel.org,
	Mike Travis <travis@....com>,
	Jeremy Fitzhardinge <jeremy@...source.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
	virtualization@...ts.osdl.org, xen-devel@...ts.xensource.com,
	Yinghai Lu <yhlu.kernel@...il.com>
Subject: Re: 2.6.29 git, resume from ram broken on thinkpad


* Chris Wright <chrisw@...s-sol.org> wrote:

> * Arkadiusz Miskiewicz (a.miskiewicz@...il.com) wrote:
> > On Friday 03 of April 2009, Chris Wright wrote:
> > > * Arkadiusz Miskiewicz (a.miskiewicz@...il.com) wrote:
> > > > What about 9ea09af3bd3090e8349ca2899ca2011bd94cda85 ?
> > > >
> > > > stop_machine: introduce stop_machine_create/destroy.
> > >
> > > That is later fixed in a0e280e0f33f6c859a235fb69a875ed8f3420388.
> > >
> > > Can you please verify if 2.6.29 works for you? 
> > 
> > I think that the guilty part is 
> > CONFIG_CC_STACKPROTECTOR_ALL=y
> > CONFIG_CC_STACKPROTECTOR=y
> 
> Indeed, I think you're right.  In fact...this should fix it:

Note that i had to do a manual merge of the patch (it had 3 separate 
patch corruptions) - the non-damaged version i applied is the one 
below.

	Ingo

--------------->
>From 1f23b77e09be10edb30eb03c1b03879083e3cc72 Mon Sep 17 00:00:00 2001
From: Joseph Cihula <joseph.cihula@...el.com>
Date: Mon, 30 Mar 2009 14:03:01 -0700
Subject: [PATCH] x86: disable stack-protector for __restore_processor_state()

The __restore_processor_state() fn restores %gs on resume from S3.  As
such, it cannot be protected by the stack-protector guard since %gs will
not be correct on function entry.

There are only a few other fns in this file and it should not negatively
impact kernel security that they will also have the stack-protector
guard removed (and so it's not worth moving them to another file).

Without this change, S3 resume on a kernel built with
CONFIG_CC_STACKPROTECTOR_ALL=y will fail.

Signed-off-by: Joseph Cihula <joseph.cihula@...el.com>
Cc: Arjan van de Ven <arjan@...ux.intel.com>
Cc: Tejun Heo <tj@...nel.org>
LKML-Reference: <49D13385.5060900@...el.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 arch/x86/power/Makefile |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/x86/power/Makefile b/arch/x86/power/Makefile
index 9ff4d5b..58b32db 100644
--- a/arch/x86/power/Makefile
+++ b/arch/x86/power/Makefile
@@ -1,2 +1,7 @@
+# __restore_processor_state() restores %gs after S3 resume and so should not
+# itself be stack-protected
+nostackp := $(call cc-option, -fno-stack-protector)
+CFLAGS_cpu_$(BITS).o	:= $(nostackp)
+
 obj-$(CONFIG_PM_SLEEP)		+= cpu_$(BITS).o
 obj-$(CONFIG_HIBERNATION)	+= hibernate_$(BITS).o hibernate_asm_$(BITS).o
--
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