Re: [RESEND PATCH] ARM: Recover kretprobes return address for EABI stack unwinder

[Linus Walleij]

On Mon, Aug 15, 2022 at 1:06 PM Chen Zhongjin <chenzhongjin@xxxxxxxxxx> wrote:

> 'fed240d9c974 ("ARM: Recover kretprobe modified return address in stacktrace")'
> has implemented kretprobes return address recovery for FP
> unwinder, this patch makes it works for EABI unwinder.
>
> It saves __kretprobe_trampoline address in LR on stack to identify
> and recover the correct return address in EABI unwinder.
>
> Since EABI doesn't use r11 as frame pointer, we need to use SP to
> identify different kretprobes addresses. Here the value of SP has fixed
> distance to conventional FP position so it's fine to use it.
>
> Passed kunit kprobes_test on QEMU.
>
> Signed-off-by: Chen Zhongjin <chenzhongjin@xxxxxxxxxx>

This looks correct to me FWIW I understand the assembly
but I'm vaguely unfamiliar with the kprobe API, but anyway:
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Would you please drop it into Russell's patch tracker?

Yours,
Linus Walleij