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| author | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2009-08-27 12:46:35 -0700 |
|---|---|---|
| committer | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2009-09-09 16:37:39 -0700 |
| commit | 577eebeae34d340685d8985dfdb7dfe337c511e8 (patch) | |
| tree | 047aa135d143ed12035ca04433e563b948f9b059 /arch/x86/xen/smp.c | |
| parent | e07cccf4046978df10f2e13fe2b99b2f9b3a65db (diff) | |
xen: make -fstack-protector work under Xen
-fstack-protector uses a special per-cpu "stack canary" value.
gcc generates special code in each function to test the canary to make
sure that the function's stack hasn't been overrun.
On x86-64, this is simply an offset of %gs, which is the usual per-cpu
base segment register, so setting it up simply requires loading %gs's
base as normal.
On i386, the stack protector segment is %gs (rather than the usual kernel
percpu %fs segment register). This requires setting up the full kernel
GDT and then loading %gs accordingly. We also need to make sure %gs is
initialized when bringing up secondary cpus too.
To keep things consistent, we do the full GDT/segment register setup on
both architectures.
Because we need to avoid -fstack-protected code before setting up the GDT
and because there's no way to disable it on a per-function basis, several
files need to have stack-protector inhibited.
[ Impact: allow Xen booting with stack-protector enabled ]
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Diffstat (limited to 'arch/x86/xen/smp.c')
| -rw-r--r-- | arch/x86/xen/smp.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c index 429834ec168..fe03eeed7b4 100644 --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -236,6 +236,7 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle) ctxt->user_regs.ss = __KERNEL_DS; #ifdef CONFIG_X86_32 ctxt->user_regs.fs = __KERNEL_PERCPU; + ctxt->user_regs.gs = __KERNEL_STACK_CANARY; #else ctxt->gs_base_kernel = per_cpu_offset(cpu); #endif |