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>
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
index 2383e5b..36a700a 100644
--- a/arch/x86/include/asm/stackprotector.h
+++ b/arch/x86/include/asm/stackprotector.h
@@ -2,7 +2,7 @@
#define _ASM_STACKPROTECTOR_H 1
#include <asm/tsc.h>
-#include <asm/pda.h>
+#include <asm/processor.h>
/*
* Initialize the stackprotector canary value.
@@ -19,7 +19,7 @@
* Build time only check to make sure the stack_canary is at
* offset 40 in the pda; this is a gcc ABI requirement
*/
- BUILD_BUG_ON(offsetof(struct x8664_pda, stack_canary) != 40);
+ BUILD_BUG_ON(offsetof(union irq_stack_union, stack_canary) != 40);
/*
* We both use the random pool and the current TSC as a source
@@ -32,7 +32,7 @@
canary += tsc + (tsc << 32UL);
current->stack_canary = canary;
- write_pda(stack_canary, canary);
+ percpu_write(irq_stack_union.stack_canary, canary);
}
#endif