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

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Date:   Tue, 7 Jul 2020 09:37:03 +0800
From:   "liwei (GF)" <liwei391@...wei.com>
To:     Doug Anderson <dianders@...omium.org>
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

Hi Doug,

On 2020/6/30 5:20, Doug Anderson wrote:
> 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.
> 

Sorry for the long delay. I was busy on a project and missed some mail.
I did receive some feedback about typo or coding style before, so i was expecting
more comment about the logic or people just don't care about these. After all,
this issue has lived a very long time.

It's a good news to hear that Will has plan to solve these issues, i will
follow that to do my bit.
Before that, i can send the next version in this week.


Thanks,
Wei