linux-kernel - Re: [PATCH V1 0/5] riscv: Add k/uprobe supported

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Message-ID: <CAOJsxLFSH2_e03xo_HMqKAzVE+2Y9=hriv-Zu=GdVUHgDMgYtw@mail.gmail.com>
Date:   Sat, 4 Jul 2020 21:30:50 +0300
From:   Pekka Enberg <penberg@...il.com>
To:     Guo Ren <guoren@...nel.org>
Cc:     Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Anup Patel <anup@...infault.org>,
        Greentime Hu <greentime.hu@...ive.com>,
        Zong Li <zong.li@...ive.com>,
        Patrick Stählin <me@...ki.ch>,
        bjorn.topel@...il.com, Atish Patra <atish.patra@....com>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Guo Ren <guoren@...ux.alibaba.com>,
        LKML <linux-kernel@...r.kernel.org>, linux-csky@...r.kernel.org
Subject: Re: [PATCH V1 0/5] riscv: Add k/uprobe supported

Hi Guo,

On Sat, Jul 4, 2020 at 6:34 AM <guoren@...nel.org> wrote:
> > > There is no single step exception in riscv ISA, so utilize ebreak to
> > > simulate. Some pc related instructions couldn't be executed out of line
> > > and some system/fence instructions couldn't be a trace site at all.
> > > So we give out a reject list and simulate list in decode-insn.c.

On Sat, Jul 4, 2020 at 2:40 PM Pekka Enberg <penberg@...il.com> wrote:
> > Can you elaborate on what you mean by this? Why would you need a
> > single-step facility for kprobes? Is it for executing the instruction
> > that was replaced with a probe breakpoint?

On Sat, Jul 4, 2020 at 5:55 PM Guo Ren <guoren@...nel.org> wrote:
> It's the single-step exception, not single-step facility!

Aah, right, I didn't read the specification carefully enough. Thanks
for taking the time to clarify this!

FWIW, for the whole series:

Reviewed-by: Pekka Enberg <penberg@...nel.org>

- Pekka