[tip:x86/urgent] x86: Fix VMI && stack protector

[tip-bot for Alok Kataria]

Commit-ID:  7d5b005652bc5ae3e1e0efc53fd0e25a643ec506
Gitweb:     http://git.kernel.org/tip/7d5b005652bc5ae3e1e0efc53fd0e25a643ec506
Author:     Alok Kataria <akataria@xxxxxxxxxx>
AuthorDate: Tue, 4 Aug 2009 15:34:22 -0700
Committer:  Ingo Molnar <mingo@xxxxxxx>
CommitDate: Wed, 5 Aug 2009 10:20:29 +0200

x86: Fix VMI && stack protector

With CONFIG_STACK_PROTECTOR turned on, VMI doesn't boot with
more than one processor. The problem is with the gs value not
being initialized correctly when registering the secondary
processor for VMI's case.

The patch below initializes the gs value for the AP to
__KERNEL_STACK_CANARY. Without this the secondary processor
keeps on taking a GP on every gs access.

Signed-off-by: Alok N Kataria <akataria@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxx> # for v2.6.30.x
LKML-Reference: <1249425262.18955.40.camel@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
 arch/x86/kernel/vmi_32.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/vmi_32.c b/arch/x86/kernel/vmi_32.c
index b263423..95a7289 100644
--- a/arch/x86/kernel/vmi_32.c
+++ b/arch/x86/kernel/vmi_32.c
@@ -441,7 +441,7 @@ vmi_startup_ipi_hook(int phys_apicid, unsigned long start_eip,
 	ap.ds = __USER_DS;
 	ap.es = __USER_DS;
 	ap.fs = __KERNEL_PERCPU;
-	ap.gs = 0;
+	ap.gs = __KERNEL_STACK_CANARY;
 
 	ap.eflags = 0;
 
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