[PATCH] x86_64: Add kernel thread stack frame termination for properly stopping stack unwinds.

One open question: Should these added pushes perhaps be made
conditional upon CONFIG_STACK_UNWIND or CONFIG_UNWIND_INFO?
[AK: Not needed -- these are all very slow paths]

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 6f810424df44..aa8d8939abc1 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -973,6 +973,8 @@ ENTRY(kernel_thread)
 ENDPROC(kernel_thread)
         
 child_rip:
+        pushq $0                # fake return address
+        CFI_STARTPROC
         /*
          * Here we are in the child and the registers are set as they were
          * at kernel_thread() invocation in the parent.
@@ -983,6 +985,7 @@ child_rip:
         # exit
         xorl %edi, %edi
         call do_exit
+        CFI_ENDPROC
 ENDPROC(child_rip)
 
 /*
diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S
index 6df05e6034fa..c9739ca81d06 100644
--- a/arch/x86_64/kernel/head.S
+++ b/arch/x86_64/kernel/head.S
@@ -191,6 +191,7 @@ startup_64:
          * jump
          */
         movq    initial_code(%rip),%rax
+        pushq   $0              # fake return address
         jmp     *%rax
 
         /* SMP bootup changes these two */