From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: pvops dom0 work roadmap
Date: Thu, 20 Aug 2009 09:22:41 -0700
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To: M A Young <m.a.young@durham.ac.uk>
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On 08/20/09 03:43, M A Young wrote:
>> Ah, right, stackprotector.  Please try the patches below (or try current
>> rebase/master).
>
>
> That doesn't help. Perhaps this is because xen_init_irq_ops is in
> irq.c, not enlighten.c though I am at a bit of a loss why
> stackprotector should care about that code segment anyway.

On i386, if %gs hasn't been loaded properly then using it as a base for
a memory access will GP.

Try this:

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 2e58099..3ebcbb2 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -51,6 +51,7 @@
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <asm/reboot.h>
+#include <asm/stackprotector.h>
 
 #include "xen-ops.h"
 #include "mmu.h"
@@ -1013,13 +1014,8 @@ asmlinkage void __init xen_start_kernel(void)
 	pv_apic_ops = xen_apic_ops;
 	pv_mmu_ops = xen_mmu_ops;
 
-#ifdef CONFIG_X86_64
-	/*
-	 * Setup percpu state.  We only need to do this for 64-bit
-	 * because 32-bit already has %fs set properly.
-	 */
-	load_percpu_segment(0);
-#endif
+	setup_stack_canary_segment(0);
+	switch_to_new_gdt(0);
 
 	xen_init_irq_ops();
 	xen_init_cpuid_mask();

Thanks,
	J