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, 0 insertions, 3 deletions

diff --git a/arch/x86/include/asm/pda.h b/arch/x86/include/asm/pda.h
index b473e952439a..ba46416634f0 100644
--- a/arch/x86/include/asm/pda.h
+++ b/arch/x86/include/asm/pda.h
@@ -17,9 +17,6 @@ struct x8664_pda {
         unsigned long unused4;
         int unused5;
         unsigned int unused6;           /* 36 was cpunumber */
-        unsigned long stack_canary;     /* 40 stack canary value */
-                                        /* gcc-ABI: this canary MUST be at
-                                           offset 40!!! */
         short in_bootmem;               /* pda lives in bootmem */
 } ____cacheline_aligned_in_smp;