linux-kernel - Re: [PATCH v10 2/4] LoongArch: Add kprobe support

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Message-ID: <CAAhV-H6LrhiYPtjeiTOp6fT4pdo8j-KvtRXjvSjeGtsbF4FY=A@mail.gmail.com>
Date:   Sat, 17 Dec 2022 10:08:57 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc:     "Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
        WANG Xuerui <kernel@...0n.name>, loongarch@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 2/4] LoongArch: Add kprobe support

Hi, all,

This series seems have too many problems, so I will drop it. So Tiezhu
please export the latest patches from
https://github.com/loongson/linux/commits/loongarch-next, and do
modifications on top of them.

Huacai

On Fri, Dec 16, 2022 at 5:33 PM Tiezhu Yang <yangtiezhu@...ngson.cn> wrote:
>
>
>
> On 12/14/2022 03:28 PM, Masami Hiramatsu (Google) wrote:
> > Hi,
> >
> > On Fri,  9 Dec 2022 16:52:59 +0800
> > Tiezhu Yang <yangtiezhu@...ngson.cn> wrote:
> >
> >> Kprobes allows you to trap at almost any kernel address and
> >> execute a callback function, this commit adds kprobe support
> >> for LoongArch.
>
> ...
>
> >> +    case KPROBE_HIT_ACTIVE:
> >> +    case KPROBE_HIT_SSDONE:
> >
> > Recently, I removed these cases because this page fault will be finally
> > handled by the generic pagefault handler.
> >
>
> Hi Masami,
>
> I have addressed all your comments on my local machine, the code logic
> looks much more clear now, thank you very much.
>
> When I test kprobe_example.ko with a C function like "kernel_clone",
> it works well, but the kernel hangs [1] when test with an assembler
> function like "__memset_fast" [2].
>
> Just did some quick research and it seems the bug is related with
> kallsyms_lookup_name(), I'm looking for a solution.
>
> [1]
> https://lore.kernel.org/loongarch/CAEr6+EC2wPAtK8zb3=e1mUiya3gv0UhqF9J_ySYx9p_96pB+tg@mail.gmail.com/
> [2]
> https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson.git/tree/arch/loongarch/lib/memset.S?h=loongarch-next#n56
>
> Thanks,
> Tiezhu
>
>