linux-kernel - Re: [External] Re: [PATCH v2] riscv: Dump user opcode bytes on fatal faults

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Message-ID: <871qg29eb7.fsf@all.your.base.are.belong.to.us>
Date:   Thu, 17 Aug 2023 12:02:52 +0200
From:   Björn Töpel <bjorn@...nel.org>
To:     yunhui cui <cuiyunhui@...edance.com>
Cc:     conor.dooley@...rochip.com, paul.walmsley@...ive.com,
        palmer@...belt.com, aou@...s.berkeley.edu, peterz@...radead.org,
        mpe@...erman.id.au, jpoimboe@...nel.org, mark.rutland@....com,
        svens@...ux.ibm.com, guoren@...nel.org, jszhang@...nel.org,
        ebiederm@...ssion.com, bjorn@...osinc.com, heiko@...ech.de,
        xianting.tian@...ux.alibaba.com, mnissler@...osinc.com,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [External] Re: [PATCH v2] riscv: Dump user opcode bytes on
 fatal faults

yunhui cui <cuiyunhui@...edance.com> writes:

> Hi Björn,
>
> On Wed, Aug 16, 2023 at 11:11 PM Björn Töpel <bjorn@...nel.org> wrote:
>>
>> Hi Yunhui,
>>
>> Waking up the dead! ;-)
>>
>
>>
>> X86's show_opcodes() is used both for kernel oops:es, and userland
>> unhandled signals. On RISC-V there's dump_kernel_instr() added in commit
>> eb165bfa8eaf ("riscv: Add instruction dump to RISC-V splats").
>>
>> Wdyt about reworking that function, so that it works for userland epc as
>> well? I think it's useful to have the surrounding instruction context,
>> and not just on instruction.
>
> Okay,  Based on your suggestion, I'm going to rename dump_kernel_instr
> to dump_instr. Like:
> static void dump_instr(const char *loglvl, struct pt_regs *regs)
> {
> ...
>                 if (user_mode(regs))
>                         bad = get_user_nofault(val, &insns[i]);
>                 else
>                         bad = get_kernel_nofault(val, &insns[i]);
> ...
> }
>
> What do you think?

Yeah, looks good! Does that work for you?


Björn