x86: push old stack address on irqstack for unwinder
Impact: Fixes dumpstack and KDB on 64 bits
This re-adds the old stack pointer to the top of the irqstack to help
with unwinding. It was removed in commit d99015b1abbad743aa049b439c1e1dede6d0fa49
as part of the save_args out-of-line work.
Both dumpstack and KDB require this information.
Signed-off-by: Martin Hicks <mort@sgi.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index e28c7a9..a134621 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -346,6 +346,7 @@
popq_cfi %rax /* move return address... */
mov %gs:pda_irqstackptr,%rsp
EMPTY_FRAME 0
+ pushq_cfi %rbp /* backlink for unwinder */
pushq_cfi %rax /* ... to the new stack */
/*
* We entered an interrupt context - irqs are off: