x86: disable stack-protector for __restore_processor_state()

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From: Linux Kernel Mailing List
Date: Friday, April 3, 2009 - 6:04 pm

Gitweb:     http://git.kernel.org/linus/9b7b89efa3bdaceaa2efb93e2d635391835da209
Commit:     9b7b89efa3bdaceaa2efb93e2d635391835da209
Parent:     6a491e2e3e52a64c6d88a192c56499d931842ac5
Author:     Joseph Cihula <joseph.cihula@intel.com>
AuthorDate: Mon Mar 30 14:03:01 2009 -0700
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Fri Apr 3 19:48:41 2009 +0200

    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@intel.com>
    Tested-by: Chris Wright <chrisw@sous-sol.org>
    Cc: Arjan van de Ven <arjan@linux.intel.com>
    Cc: Tejun Heo <tj@kernel.org>
    LKML-Reference: <49D13385.5060900@intel.com>
    Signed-off-by: Ingo Molnar <mingo@elte.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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x86: disable stack-protector for __restore_processor_state(), Linux Kernel Mailing ..., (Fri Apr 3, 6:04 pm)