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From:   Pekka Enberg <penberg@gmail.com>
Date:   Sat, 4 Jul 2020 21:30:50 +0300
Message-ID: <CAOJsxLFSH2_e03xo_HMqKAzVE+2Y9=hriv-Zu=GdVUHgDMgYtw@mail.gmail.com>
Subject: Re: [PATCH V1 0/5] riscv: Add k/uprobe supported
To:     Guo Ren <guoren@kernel.org>
Cc:     Palmer Dabbelt <palmerdabbelt@google.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Anup Patel <anup@brainfault.org>,
        Greentime Hu <greentime.hu@sifive.com>,
        Zong Li <zong.li@sifive.com>,
        =?UTF-8?Q?Patrick_St=C3=A4hlin?= <me@packi.ch>,
        bjorn.topel@gmail.com, Atish Patra <atish.patra@wdc.com>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Guo Ren <guoren@linux.alibaba.com>,
        LKML <linux-kernel@vger.kernel.org>, linux-csky@vger.kernel.org
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Hi Guo,

On Sat, Jul 4, 2020 at 6:34 AM <guoren@kernel.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@gmail.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@kernel.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@kernel.org>

- Pekka