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From: Mark Rutland <mark.rutland@arm.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Mark Brown <broonie@kernel.org>,
	linux-kernel@vger.kernel.org, Jiri Kosina <jikos@kernel.org>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>, Miroslav Benes <mbenes@suse.cz>,
	linux-doc@vger.kernel.org, live-patching@vger.kernel.org,
	Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH v4] Documentation: livepatch: document reliable stacktrace
Date: Mon, 18 Jan 2021 17:50:54 +0000	[thread overview]
Message-ID: <20210118175054.GB38844@C02TD0UTHF1T.local> (raw)
In-Reply-To: <YAWU0D50KH4mVTgn@alley>

Hi Petr,

On Mon, Jan 18, 2021 at 03:02:31PM +0100, Petr Mladek wrote:
> On Fri 2021-01-15 17:16:17, Mark Brown wrote:
> > I've made a few assumptions about preferred behaviour, notably:
> > 
> > * If you can reliably unwind through exceptions, you should (as x86_64
> >   does).

IIRC this was confirmed as desireable, and the text already reflects
this.

> > * It's fine to omit ftrace_return_to_handler and other return
> >   trampolines so long as these are not subject to patching and the
> >   original return address is reported. Most architectures do this for
> >   ftrace_return_handler, but not other return trampolines.

Likewise I think we agreed this was fine, given these were not
themselves subkect to patching.

> > * For cases where link register unreliability could result in duplicate
> >   entries in the trace or an inverted trace, I've assumed this should be
> >   treated as unreliable. This specific case shouldn't matter to
> >   livepatching, but I assume that that we want a reliable trace to have
> >   the correct order.

I don't think we had any comments either way on this, but I think it's
sane to say this for now and later relax it if we need to.

... so I reckon we can just delete all this as Josh suggests. Any acks
for the patch itself tacitly agrees with these points. :)

Thanks,
Mark.

      parent reply	other threads:[~2021-01-18 17:52 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-15 17:16 [PATCH v4] Documentation: livepatch: document reliable stacktrace Mark Brown
2021-01-18 14:02 ` Petr Mladek
2021-01-18 14:54   ` Josh Poimboeuf
2021-01-18 17:50   ` Mark Rutland [this message]

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