linux-kernel - Re: [PATCH v3 0/2] arm64: Fix pending single-step debugging issues

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Date:   Mon, 11 Jul 2022 19:21:51 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Daniel Thompson <daniel.thompson@...aro.org>,
        Will Deacon <will@...nel.org>, Wei Li <liwei391@...wei.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Rutland <mark.rutland@....com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jason Wessel <jason.wessel@...driver.com>,
        Marc Zyngier <maz@...nel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/2] arm64: Fix pending single-step debugging issues

On Mon, 11 Jul 2022 at 19:17, Doug Anderson <dianders@...omium.org> wrote:
>
> Hi,
>
> On Mon, Jul 11, 2022 at 5:44 AM Sumit Garg <sumit.garg@...aro.org> wrote:
> >
> > > I'll also note that I _think_ I remember that with Wei's series that
> > > the gdb function "call" started working. I tried that here and it
> > > didn't seem so happy. To keep things simple, I created a dummy
> > > function in my kernel that looked like:
> > >
> > > void doug_test(void)
> > > {
> > >   pr_info("testing, 1 2 3\n");
> > > }
> > >
> > > I broke into the debugger by echoing "g" to /proc/sysrq-trigger and
> > > then tried "call doug_test()". I guess my printout actually printed
> > > but it wasn't so happy after that. Seems like it somehow ended up
> > > returning to a bogus address after the call which then caused a crash.
> > >
> >
> > I am able to reproduce this issue on my setup as well. But it doesn't
> > seem to be a regression caused by this patch-set over Wei's series. As
> > I could reproduce this issue with v1 [1] patch-set as well which was
> > just a forward port of pending patches from Wei's series to the latest
> > upstream.
> >
> > Maybe it's a different regression caused by other changes? BTW, do you
> > remember the kernel version you tested with Wei's series applied?
>
> Sorry, I don't remember! :( I can't even be 100% sure that I'm
> remembering correctly that I tested it back in the day, so it's
> possible that it simply never worked...

Okay, no worries. Let me see if I can come up with a separate fix for this.

-Sumit

>
> -Doug