[Question] About UNWIND_HINT_ENTRY on entry_SYSCALL_64.

From: Yun Levi
Date: Fri Nov 25 2022 - 05:42:04 EST


Hello.

While I try to see the information related to ORC in vmlinux,
I'm trying to find out ORC information related to entry_SYSCALL_64's address.

For this, I've tried to take the following step:
1. booting the kernel with the "nokaslr" option.
2. Getting ORC information by "objdump orc dump vmlinux"
3. cat /proc/kallsyms and check the address of "entry_SYSCALL_64"
- In my kernel, It's address .text + a00000
4. Find out related ORC entry gotten in step 2.

But, I couldn't find the reason why entry_SYSCALL_64's orc info isn't
encoded with end =1.
Instead, It was encoded as INVALID ORC entry like:

.text+a00000: sp:(und) bp:(und) type:call end:0

IIUC, Some of the code is started with UNWIND_HINT_ENTRY or UNWIND_HINT_EMPTY,
it should be encoded with end = 1. But it doesn't.

Am I wrong?


--
Sincerely,
Levi