x86: move stack_canary into irq_stack

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>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
index b77bd8bd3cc2..52eb748a68af 100644
--- a/arch/x86/include/asm/system.h
+++ b/arch/x86/include/asm/system.h
@@ -89,10 +89,10 @@ do {									\
 #ifdef CONFIG_CC_STACKPROTECTOR
 #define __switch_canary                                                   \
         "movq %P[task_canary](%%rsi),%%r8\n\t"                            \
-        "movq %%r8,%%gs:%P[pda_canary]\n\t"
+        "movq %%r8,%%gs:%P[gs_canary]\n\t"
 #define __switch_canary_param                                             \
         , [task_canary] "i" (offsetof(struct task_struct, stack_canary))  \
-        , [pda_canary] "i" (offsetof(struct x8664_pda, stack_canary))
+        , [gs_canary] "i" (offsetof(union irq_stack_union, stack_canary))
 #else   /* CC_STACKPROTECTOR */
 #define __switch_canary
 #define __switch_canary_param