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

[Chen Zhongjin <chenzhongjin@huawei.com>]

On 2022/8/22 19:20, Linus Walleij wrote:
> On Mon, Aug 15, 2022 at 1:06 PM Chen Zhongjin <chenzhongjin@huawei.com> 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@huawei.com>
> 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@linaro.org>
>
> Would you please drop it into Russell's patch tracker?

Done for it.

Thanks for review!


Best,

Chen

> Yours,
> Linus Walleij