Re: [PATCH v4 5/9] riscv: Add kprobes supported

Guo Ren
2020-11-06T02:57:14Z

On Fri, Nov 6, 2020 at 9:02 AM Palmer Dabbelt <palmerdabbelt@google.com> wrote:
>
> 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@packi.ch/
> > [2] https://lore.kernel.org/linux-csky/20200403044150.20562-9-guoren@kernel.org/
> >
> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> > Co-Developed-by: Patrick Stählin <me@packi.ch>
>
> Checkpatch says
>
> WARNING: 'Co-developed-by:' is the preferred signature form
> #108:
> Co-Developed-by: Patrick Stählin <me@packi.ch>
>
> WARNING: Co-developed-by: must be immediately followed by Signed-off-by:
> #108:
> Co-Developed-by: Patrick Stählin <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

--
Best Regards
Guo Ren

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