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From:   Kalesh Singh <kaleshsingh@google.com>
Date:   Mon, 27 Jun 2022 09:32:30 -0700
Message-ID: <CAC_TJveqCTToimvrrTrEcRAxERL0EW+61PxS9emb-u51Eo4Eug@mail.gmail.com>
Subject: Re: [PATCH v15 0/6] arm64: Reorganize the unwinder and implement
 stack trace reliability checks
To:     "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
Cc:     Mark Rutland <mark.rutland@arm.com>, Will Deacon <will@kernel.org>,
        Mark Brown <broonie@kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Ard Biesheuvel <ardb@kernel.org>, nobuta.keiya@fujitsu.com,
        sjitindarsingh@gmail.com,
        Catalin Marinas <catalin.marinas@arm.com>,
        James Morris <jamorris@linux.microsoft.com>,
        "moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)" 
        <linux-arm-kernel@lists.infradead.org>,
        live-patching@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        Marc Zyngier <maz@kernel.org>
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On Sun, Jun 26, 2022 at 9:33 PM Madhavan T. Venkataraman
<madvenka@linux.microsoft.com> wrote:
>
>
>
> On 6/26/22 04:18, Mark Rutland wrote:
> > On Fri, Jun 24, 2022 at 12:19:01AM -0500, Madhavan T. Venkataraman wrote:
> >>
> >>
> >> On 6/23/22 12:32, Will Deacon wrote:
> >>> On Fri, Jun 17, 2022 at 04:07:11PM -0500, madvenka@linux.microsoft.com wrote:
> >>>> From: "Madhavan T. Venkataraman" <madvenka@linux.microsoft.com>
> >>>>
> >>>> I have synced this patch series to v5.19-rc2.
> >>>> I have also removed the following patch.
> >>>>
> >>>>    [PATCH v14 7/7] arm64: Select HAVE_RELIABLE_STACKTRACE
> >>>>
> >>>> as HAVE_RELIABLE_STACKTRACE depends on STACK_VALIDATION which is not present
> >>>> yet. This patch will be added in the future once Objtool is enhanced to
> >>>> provide stack validation in some form.
> >>>
> >>> Given that it's not at all obvious that we're going to end up using objtool
> >>> for arm64, does this patch series gain us anything in isolation?
> >>>
> >>
> >> BTW, I have synced my patchset to 5.19-rc2 and sent it as v15.
> >>
> >> So, to answer your question, patches 1 thru 3 in v15 are still useful even if we don't
> >> consider reliable stacktrace. These patches reorganize the unwinder code based on
> >> comments from both Mark Rutland and Mark Brown. Mark Brown has already OKed them.
> >> If Mark Rutland OKes them, we should upstream them.
> >
> > Sorry for the delay; I have been rather swamped recently and haven't had the
> > time to give this the time it needs.
> >
> > I'm happy with patches 1 and 2, and I've acked those in case Will wants to pick
> > them.
> >
> > Kalesh (cc'd) is working to share the unwinder code with hyp, and I think that
> > we need to take a step back and consider how we can make the design work
> > cleanly with that. I'd had a go at prototyping making the unwinder more data
> > driven, but I haven't come up with something satisfactory so far.
> >
> > It would be good if you could look at / comment on each others series.
> >
>
> I will review Kalesh's unwinder changes.

Thanks Mark, I'll take a look.

Madhavan, I'm in the process of preparing a new version. Let me rebase
on your first 2 patches and resend, so you can look at that version
instead.

Thanks,
Kalesh

>
> Thanks.
>
> Madhavan