The frame at the end of each idle task stack has a zero instead of a
real return address. This is inconsistent with real task stacks, which
have a real return address at that spot. This inconsistency can be
confusing for stack unwinders.
Make it a real address by using the side effect of a call instruction to
push the instruction pointer on the stack.
Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
arch/x86/kernel/head_64.S | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index ac6e27e..c910c27 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -296,8 +296,9 @@ ENTRY(start_cpu)
* REX.W + FF /5 JMP m16:64 Jump far, absolute indirect,
* address given in m16:64.
*/
- movq initial_code(%rip),%rax
- pushq $0 # fake return address to stop unwinder
+ call 1f # put return address on stack for unwinder
+1: xorq %rbp, %rbp # clear frame pointer
+ movq initial_code(%rip), %rax
pushq $__KERNEL_CS # set correct cs
pushq %rax # target address in negative space
lretq
--
2.7.4
