Re: [RFC/RFT 2/2] RISC-V: kprobes/kretprobe support

[Masami Hiramatsu <mhiramat@kernel.org>]

Hi Guo and Patrick,

On Wed, 17 Jun 2020 20:58:32 +0800
Guo Ren <guoren@kernel.org> wrote:

> Hi Patrick,
> 
> I'm the author of csky's kprobe & uprobe, please ref to kprobe [1], uprobe [2]
> 
> 1: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/csky?h=v5.8-rc1&id=33e53ae1ce413a081254e686d9b27cc1b3585e2f
> 2: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/csky?h=v5.8-rc1&id=8f6bb793b2be82f1f73bfb416486f156f70b4314

Thanks for the porting!

> 
> May I continue your patches to finish the work? I'll keep the primary
> author's name of you with the patches which you've done.
> 
> Most of the instructions' emulation codes will be deprecated, but the
> rest is ok. Maybe you should finish executing out of the slot first
> and then implement pc-related instructions' emulation.

I can review the patch if you update it. Anyway, my major concern was the
self-modifying code, others are minor points. 

Thank you,

> 
> On Fri, Jun 12, 2020 at 1:58 PM David Abdurachmanov
> <david.abdurachmanov@gmail.com> wrote:
> >
> > On Tue, Mar 31, 2020 at 5:45 AM Zong Li <zong.li@sifive.com> wrote:
> > >
> > > On Thu, Dec 19, 2019 at 5:28 PM Zong Li <zong.li@sifive.com> wrote:
> > > >
> > > > On Wed, Dec 18, 2019 at 9:10 PM Patrick Stählin <me@packi.ch> wrote:
> > > > >
> > > > > Hi all
> > > > >
> > > > > On 18.12.19 10:14, Zong Li wrote:
> > > > > > On Wed, Dec 18, 2019 at 5:09 PM Zong Li <zong.li@sifive.com> wrote:
> > > > > >>
> > > > > >> From: mhiramat@kernel.org (Masami Hiramatsu)
> > > > > >>
> > > > > >> On Wed, 14 Nov 2018 21:52:57 +0100
> > > > > >> Patrick Staehlin <me@packi.ch> wrote:
> > > > > >>
> > > > > >>> Yeah, I think it's simpler.
> > > > > >>>
> > > > > >>> And I found that the kprobe_breakpoint_handler() was called without
> > > > > >>> checking !user_mode(regs). In that case, you should add the check in
> > > > > >>> front of kprobe_breakpoint_handler() call.
> > > > > >>>
> > > > > >>> Thank you,
> > > > > >>
> > > > > >> Hi all,
> > > > > >>
> > > > > >> Is there any update? I was wondering if this patch are keep going? If
> > > > > >> not, I think I could pick it up to go head
> > > > >
> > > > > I am still working on it, albeit slowly, holiday season coming up here
> > > > > in Switzerland may accelerate that a bit. All the feedback I got from
> > > > > Masami has been implemented.
> > > >
> > > > As Masami's suggestion, I don't see stop_machine in your implementation [1],
> > > > are there some concerns to use it on SMP?
> > >
> > > Hi all,
> > > I introduced the patching code framework. Maybe it is helpful for
> > > self-modify code here. (Please see:
> > > https://lkml.org/lkml/2020/3/9/679)
> > > This patch series is reviewing, maybe we could apply the
> > > implementation after it was merged.
> > >
> > >
> > > >
> > > > > Additionally I added instruction simulation for everything except memory
> > > > > accesses. I am currently working on getting compressed instructions
> > > > > decoded properly into regular instructions but that is very tedious work.
> > > > > I guess I am two or three full days of work away from getting a RFC/RFT
> > > > > v2 series ready I guess that will happen in early January.
> > > >
> > > > Thanks for the efforts.
> > > >
> > > > >
> > > > > What I currently have is at [1], that is mostly untested as of now
> > > > > (beware I will rebase/squash that branch regularly). What I could use
> > > > > help with in the future (as in for v2), is somebody testing it on real
> > > > > hardware, as I've never gotten any testing feedback on my original
> > > > > patch-series (that would not have worked properly because of the lacking
> > > > > cache-flush).
> > > >
> > > > I give some quick tests by using kprobe sanity test and simple LKM on
> > > > Hifive Unleashed board,
> > > > it seems to work normally. I could help to test your next version patch as well.
> >
> > Hi Patrick,
> >
> > I have noticed that "riscv: introduce interfaces to patch kernel code"
> > (mentioned by Zong above) has been merged in 5.7 kernel.
> >
> > I was wondering if you plan to submit a new revision of the patchset?
> >
> > Thanks,
> > david
> >
> > > >
> > > > >
> > > > > [1] https://github.com/packi/linux/tree/kprobes-riscv
> > > > >
> > > > > Patrick
> > >
> >
> 
> -- 
> Best Regards
>  Guo Ren
> 
> ML: https://lore.kernel.org/linux-csky/


-- 
Masami Hiramatsu <mhiramat@kernel.org>