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x86: move stack_canary into irq_stack

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Impact: x86_64 percpu area layout change, irq_stack now at the beginning

Now that the PDA is empty except for the stack canary, it can be removed.
The irqstack is moved to the start of the per-cpu section.  If the stack
protector is enabled, the canary overlaps the bottom 48 bytes of the irqstack.

tj: * updated subject
    * dropped asm relocation of irq_stack_ptr
    * updated comments a bit
    * rebased on top of stack canary changes

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Brian Gerst
2009-01-19 12:21:28 +09:00
committed by Tejun Heo
parent 8c7e58e690
commit 947e76cdc3
10 changed files with 46 additions and 62 deletions
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23
arch/x86/include/asm/processor.h
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@@ -379,8 +379,29 @@ union thread_xstate {
#ifdef CONFIG_X86_64
DECLARE_PER_CPU(struct orig_ist, orig_ist);
DECLARE_PER_CPU(char[IRQ_STACK_SIZE], irq_stack);
union irq_stack_union {
char irq_stack[IRQ_STACK_SIZE];
/*
* GCC hardcodes the stack canary as %gs:40. Since the
* irq_stack is the object at %gs:0, we reserve the bottom
* 48 bytes of the irq stack for the canary.
*/
struct {
char gs_base[40];
unsigned long stack_canary;
};
};
DECLARE_PER_CPU(union irq_stack_union, irq_stack_union);
DECLARE_PER_CPU(char *, irq_stack_ptr);
static inline void load_gs_base(int cpu)
{
/* Memory clobbers used to order pda/percpu accesses */
mb();
wrmsrl(MSR_GS_BASE, (unsigned long)per_cpu(irq_stack_union.gs_base, cpu));
mb();
}
#endif
extern void print_cpu_info(struct cpuinfo_x86 *);