[PATCH] x86: remove the confusing entry in call trace

[jia zhang <jia.zhang2008@gmail.com>]

avoid the confusion in call trace because of the lack of padding at the tail of function.

Signed-off-by: jia zhang <jia.zhang2008@gmail.com>
---
When do_exit get call, the return address behind call instruction is pushed into stack. If something get wrong in do_exit, for x86_64, the entry "kernel_execve +0x00/0xXX" rather than "child_rip +0xYY/0xZZ" is remained in call trace. It looks confused.

 b/arch/x86/kernel/entry_32.S |    1 +
 b/arch/x86/kernel/entry_64.S |    1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 28b597e..3290819 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1051,6 +1051,7 @@ ENTRY(kernel_thread_helper)
 	push %eax
 	CFI_ADJUST_CFA_OFFSET 4
 	call do_exit
+	nop			# padding for call trace
 	CFI_ENDPROC
 ENDPROC(kernel_thread_helper)
 
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index b86f332..6f677a6 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1170,6 +1170,7 @@ child_rip:
 	# exit
 	mov %eax, %edi
 	call do_exit
+	nop			# padding for call trace
 	CFI_ENDPROC
 ENDPROC(child_rip)