linux-kernel - Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues

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Date:   Mon, 29 Jun 2020 14:20:11 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     "liwei (GF)" <liwei391@...wei.com>
Cc:     Daniel Thompson <daniel.thompson@...aro.org>,
        Jason Wessel <jason.wessel@...driver.com>,
        Marc Zyngier <maz@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        David Miller <davem@...emloft.net>,
        Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>, liwei1412@....com
Subject: Re: [PATCH 0/4] arm64: kgdb/kdb: Fix single-step debugging issues

Wei,

On Sat, May 16, 2020 at 1:20 AM liwei (GF) <liwei391@...wei.com> wrote:
>
> Hi Douglas,
>
> On 2020/5/14 8:34, Doug Anderson wrote:
> > Hi,
> >
> > On Sat, May 9, 2020 at 6:49 AM Wei Li <liwei391@...wei.com> wrote:
> >>
> >> This patch set is to fix several issues of single-step debugging
> >> in kgdb/kdb on arm64.
> >>
> >> It seems that these issues have been shelved a very long time,
> >> but i still hope to solve them, as the single-step debugging
> >> is an useful feature.
> >>
> >> Note:
> >> Based on patch "arm64: cacheflush: Fix KGDB trap detection",
> >> https://www.spinics.net/lists/arm-kernel/msg803741.html
> >>
> >> Wei Li (4):
> >>   arm64: kgdb: Fix single-step exception handling oops
> >>   arm64: Extract kprobes_save_local_irqflag() and
> >>     kprobes_restore_local_irqflag()
> >>   arm64: kgdb: Fix single-stepping into the irq handler wrongly
> >>   arm64: kgdb: Set PSTATE.SS to 1 to reenable single-step
> >>
> >>  arch/arm64/include/asm/debug-monitors.h |  6 ++++++
> >>  arch/arm64/kernel/debug-monitors.c      | 28 ++++++++++++++++++++++++-
> >>  arch/arm64/kernel/kgdb.c                | 16 +++++++++++---
> >>  arch/arm64/kernel/probes/kprobes.c      | 28 ++-----------------------
> >>  4 files changed, 48 insertions(+), 30 deletions(-)
> >
> > Just an overall note that I'm very happy that you posted this patch
> > series!  It's always been a thorn in my side that stepping and
> > breakpoints were so broken on arm64 and I'm really excited that you're
> > fixing them.  Now I'll have to get in the habit of using kgdb for more
> > than just debugging crashes and maybe I can use it more for exploring
> > how functions work more.  :-)
> > > I'll also note that with your patch series I'm even seeing the "call"
> > feature of gdb working now.  That has always been terribly broken for
> > me.
> >
> Thanks for reviewing and testing this series.
> Enjoy exploring the kernel with kgdb/kdb! :-)

I'm curious to know if you plan another spin.  The feedback you
received was fairly minor so it hopefully shouldn't be too hard.  I'd
very much like to get your patches landed and I'd be happy to try to
address the feedback and spin them myself if you're no longer
available for it.

Thanks!

-Doug