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From:   Doug Anderson <dianders@chromium.org>
Date:   Mon, 11 Jul 2022 06:47:18 -0700
Message-ID: <CAD=FV=WdMsqrsWzX=0RU5HJ1a0cy-pm4BwP47siLj=+eeEXUQA@mail.gmail.com>
Subject: Re: [PATCH v3 0/2] arm64: Fix pending single-step debugging issues
To:     Sumit Garg <sumit.garg@linaro.org>
Cc:     Daniel Thompson <daniel.thompson@linaro.org>,
        Will Deacon <will@kernel.org>, Wei Li <liwei391@huawei.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Jason Wessel <jason.wessel@windriver.com>,
        Marc Zyngier <maz@kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>
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Hi,

On Mon, Jul 11, 2022 at 5:44 AM Sumit Garg <sumit.garg@linaro.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...

-Doug