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lguest: fix 'unhandled trap 13' with CONFIG_CC_STACKPROTECTOR

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We don't set up the canary; let's disable stack protector on boot.c so
we can get into lguest_init, then set it up.  As a side effect,
switch_to_new_gdt() sets up %fs for us properly too.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Rusty Russell 2009-06-03 14:52:24 +09:30 committed by Linus Torvalds
parent 9fa7eb283c
commit 2cb7878a3a
2 changed files with 14 additions and 4 deletions
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1
arch/x86/lguest/Makefile
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@ -1 +1,2 @@
obj-y := i386_head.o boot.o
CFLAGS_boot.o := $(call cc-option, -fno-stack-protector)

17
arch/x86/lguest/boot.c
View file

@ -67,6 +67,7 @@
#include <asm/mce.h>
#include <asm/io.h>
#include <asm/i387.h>
#include <asm/stackprotector.h>
#include <asm/reboot.h> /* for struct machine_ops */
/*G:010 Welcome to the Guest!
@ -1088,13 +1089,21 @@ __init void lguest_init(void)
* lguest_init() where the rest of the fairly chaotic boot setup
* occurs. */
/* The stack protector is a weird thing where gcc places a canary
* value on the stack and then checks it on return. This file is
* compiled with -fno-stack-protector it, so we got this far without
* problems. The value of the canary is kept at offset 20 from the
* %gs register, so we need to set that up before calling C functions
* in other files. */
setup_stack_canary_segment(0);
/* We could just call load_stack_canary_segment(), but we might as
* call switch_to_new_gdt() which loads the whole table and sets up
* the per-cpu segment descriptor register %fs as well. */
switch_to_new_gdt(0);
/* As described in head_32.S, we map the first 128M of memory. */
max_pfn_mapped = (128*1024*1024) >> PAGE_SHIFT;
/* Load the %fs segment register (the per-cpu segment register) with
* the normal data segment to get through booting. */
asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_DS) : "memory");
/* The Host<->Guest Switcher lives at the top of our address space, and
* the Host told us how big it is when we made LGUEST_INIT hypercall:
* it put the answer in lguest_data.reserve_mem */