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From:   Guo Ren <guoren@kernel.org>
Date:   Fri, 6 Nov 2020 10:56:54 +0800
Message-ID: <CAJF2gTSWubMT3hk4pMg5my9=6G+U+8+Wx_Hzud+rxLgn6Ah6kw@mail.gmail.com>
Subject: Re: [PATCH v4 5/9] riscv: Add kprobes supported
To:     Palmer Dabbelt <palmerdabbelt@google.com>
Cc:     Paul Walmsley <paul.walmsley@sifive.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Alan Kao <alankao@andestech.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Anup Patel <anup@brainfault.org>, linux-csky@vger.kernel.org,
        Greentime Hu <greentime.hu@sifive.com>,
        Zong Li <zong.li@sifive.com>,
        =?UTF-8?Q?Patrick_St=C3=A4hlin?= <me@packi.ch>,
        Guo Ren <guoren@linux.alibaba.com>,
        Bjorn Topel <bjorn.topel@gmail.com>
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On Fri, Nov 6, 2020 at 9:02 AM Palmer Dabbelt <palmerdabbelt@google.com> wr=
ote:
>
> On Sat, 17 Oct 2020 00:06:13 PDT (-0700), guoren@kernel.org wrote:
> > From: Guo Ren <guoren@linux.alibaba.com>
> >
> > This patch enables "kprobe & kretprobe" to work with ftrace
> > interface. It utilized software breakpoint as single-step
> > mechanism.
> >
> > Some instructions which can't be single-step executed must be
> > simulated in kernel execution slot, such as: branch, jal, auipc,
> > la ...
> >
> > Some instructions should be rejected for probing and we use a
> > blacklist to filter, such as: ecall, ebreak, ...
> >
> > We use ebreak & c.ebreak to replace origin instruction and the
> > kprobe handler prepares an executable memory slot for out-of-line
> > execution with a copy of the original instruction being probed.
> > In execution slot we add ebreak behind original instruction to
> > simulate a single-setp mechanism.
> >
> > The patch is based on packi's work [1] and csky's work [2].
> >  - The kprobes_trampoline.S is all from packi's patch
> >  - The single-step mechanism is new designed for riscv without hw
> >    single-step trap
> >  - The simulation codes are from csky
> >  - Frankly, all codes refer to other archs' implementation
> >
> >  [1] https://lore.kernel.org/linux-riscv/20181113195804.22825-1-me@pack=
i.ch/
> >  [2] https://lore.kernel.org/linux-csky/20200403044150.20562-9-guoren@k=
ernel.org/
> >
> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > Co-Developed-by: Patrick St=C3=A4hlin <me@packi.ch>
>
> Checkpatch says
>
>     WARNING: 'Co-developed-by:' is the preferred signature form
>     #108:
>     Co-Developed-by: Patrick St=C3=A4hlin <me@packi.ch>
>
>     WARNING: Co-developed-by: must be immediately followed by Signed-off-=
by:
>     #108:
>     Co-Developed-by: Patrick St=C3=A4hlin <me@packi.ch>
>     Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
>
> There's some other checkpatch warnings throughout the patch set, but this=
 is
> one I'm not supposed to fix up.  Can one of you re-post the patches with =
the
> correct DCO?
Ok, I'll fix it up in V5 and rebase 5.10-rc2

--=20
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/