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x86: update canary handling during switch 

Impact: cleanup

In switch_to(), instead of taking offset to irq_stack_union.stack,
make it a proper percpu access using __percpu_arg() and per_cpu_var().

Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2009-01-21 17:26:05 +09:00
parent 8f5d36ed5b
commit 67e68bde02
1 changed files with 9 additions and 6 deletions
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15
arch/x86/include/asm/system.h
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@ -89,13 +89,15 @@ do { \
#ifdef CONFIG_CC_STACKPROTECTOR #ifdef CONFIG_CC_STACKPROTECTOR
#define __switch_canary \ #define __switch_canary \
"movq %P[task_canary](%%rsi),%%r8\n\t" \ "movq %P[task_canary](%%rsi),%%r8\n\t" \
"movq %%r8,%%gs:%P[gs_canary]\n\t" "movq %%r8,"__percpu_arg([gs_canary])"\n\t"
#define __switch_canary_param \ #define __switch_canary_oparam \
, [task_canary] "i" (offsetof(struct task_struct, stack_canary)) \ , [gs_canary] "=m" (per_cpu_var(irq_stack_union.stack_canary))
, [gs_canary] "i" (offsetof(union irq_stack_union, stack_canary)) #define __switch_canary_iparam \
, [task_canary] "i" (offsetof(struct task_struct, stack_canary))
#else /* CC_STACKPROTECTOR */ #else /* CC_STACKPROTECTOR */
#define __switch_canary #define __switch_canary
#define __switch_canary_param #define __switch_canary_oparam
#define __switch_canary_iparam
#endif /* CC_STACKPROTECTOR */ #endif /* CC_STACKPROTECTOR */
/* Save restore flags to clear handle leaking NT */ /* Save restore flags to clear handle leaking NT */
@ -114,13 +116,14 @@ do { \
"jc ret_from_fork\n\t" \ "jc ret_from_fork\n\t" \
RESTORE_CONTEXT \ RESTORE_CONTEXT \
: "=a" (last) \ : "=a" (last) \
__switch_canary_oparam \
: [next] "S" (next), [prev] "D" (prev), \ : [next] "S" (next), [prev] "D" (prev), \
[threadrsp] "i" (offsetof(struct task_struct, thread.sp)), \ [threadrsp] "i" (offsetof(struct task_struct, thread.sp)), \
[ti_flags] "i" (offsetof(struct thread_info, flags)), \ [ti_flags] "i" (offsetof(struct thread_info, flags)), \
[tif_fork] "i" (TIF_FORK), \ [tif_fork] "i" (TIF_FORK), \
[thread_info] "i" (offsetof(struct task_struct, stack)), \ [thread_info] "i" (offsetof(struct task_struct, stack)), \
[current_task] "m" (per_cpu_var(current_task)) \ [current_task] "m" (per_cpu_var(current_task)) \
__switch_canary_param \ __switch_canary_iparam \
: "memory", "cc" __EXTRA_CLOBBER) : "memory", "cc" __EXTRA_CLOBBER)
#endif #endif