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

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)


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