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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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34
arch/x86/kernel/setup_percpu.c
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@@ -77,30 +77,6 @@ static void __init setup_node_to_cpumask_map(void);
static inline void setup_node_to_cpumask_map(void) { }
#endif
/*
* Define load_pda_offset() and per-cpu __pda for x86_64.
* load_pda_offset() is responsible for loading the offset of pda into
* %gs.
*
* On SMP, pda offset also duals as percpu base address and thus it
* should be at the start of per-cpu area. To achieve this, it's
* preallocated in vmlinux_64.lds.S directly instead of using
* DEFINE_PER_CPU().
*/
#ifdef CONFIG_X86_64
void __cpuinit load_pda_offset(int cpu)
{
/* Memory clobbers used to order pda/percpu accesses */
mb();
wrmsrl(MSR_GS_BASE, cpu_pda(cpu));
mb();
}
#ifndef CONFIG_SMP
DEFINE_PER_CPU(struct x8664_pda, __pda);
#endif
EXPORT_PER_CPU_SYMBOL(__pda);
#endif /* CONFIG_SMP && CONFIG_X86_64 */
#ifdef CONFIG_X86_64
/* correctly size the local cpu masks */
@@ -207,15 +183,13 @@ void __init setup_per_cpu_areas(void)
per_cpu(cpu_number, cpu) = cpu;
#ifdef CONFIG_X86_64
per_cpu(irq_stack_ptr, cpu) =
(char *)per_cpu(irq_stack, cpu) + IRQ_STACK_SIZE - 64;
per_cpu(irq_stack_union.irq_stack, cpu) + IRQ_STACK_SIZE - 64;
/*
* CPU0 modified pda in the init data area, reload pda
* offset for CPU0 and clear the area for others.
* Up to this point, CPU0 has been using .data.init
* area. Reload %gs offset for CPU0.
*/
if (cpu == 0)
load_pda_offset(0);
else
memset(cpu_pda(cpu), 0, sizeof(*cpu_pda(cpu)));
load_gs_base(cpu);
#endif
DBG("PERCPU: cpu %4d %p\n", cpu, ptr);