Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Tue, 2 May 2023 20:38:01 -0300
From:   Marcos Paulo de Souza <mpdesouza@suse.de>
To:     Nicolai Stange <nstange@suse.de>
Cc:     Josh Poimboeuf <jpoimboe@kernel.org>,
        Joe Lawrence <joe.lawrence@redhat.com>,
        live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-kbuild@vger.kernel.org, Miroslav Benes <mbenes@suse.cz>,
        Petr Mladek <pmladek@suse.com>,
        Marcos Paulo de Souza <mpdesouza@suse.com>,
        Lukas Hruska <lhruska@suse.cz>
Subject: Re: [PATCH v7 00/10] livepatch: klp-convert tool
Message-ID: <dlivegt4sjm632m3sete73me3i2rceojfo4q4hji5ubvdcn2ly@f3tx6y5kqmkc>
References: <20230306140824.3858543-1-joe.lawrence@redhat.com>
 <20230314202356.kal22jracaw5442y@daedalus>
 <ZBTNvEPrCcRj3F1C@redhat.com>
 <20230317232010.7uq6tt4ty35eo5hm@treble>
 <873556ag24.fsf@suse.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <873556ag24.fsf@suse.de>
Precedence: bulk

On Tue, Apr 11, 2023 at 12:06:43PM +0200, Nicolai Stange wrote:
> Josh Poimboeuf <jpoimboe@kernel.org> writes:
> 
> > On Fri, Mar 17, 2023 at 04:29:48PM -0400, Joe Lawrence wrote:
> >> Have you tried retrofitting klp-convert into any real-world livepatch?
> >> I'm curious as to your observations on the overall experience, or
> >> thoughts on the sympos annotation style noted above.
> >
> > On a related note, the patch creation process (of which klp-convert
> > would be part of) needs to be documented.
> >
> > If I remember correctly, the proper safe usage of klp-convert requires a
> > kernel built with -flive-patching, plus some scripting and/or manual
> > processes.
> 
> Not always, I think: -flive-patching or IPA optimizations in general
> aren't a concern in the context of data symbols. From a quick glance, it
> seems like the selftests introduced as part of this patchset are
> all restricted to this usecase.

<snip>

> What do you think, does it make sense to eventually have such a bare
> minimum klp-convert merged in-tree, independently of the ongoing
> discussion around the livepatch preparation processes, respectively (the
> lack of) documentation around it? If yes, Lukas, now on CC, is
> interested in this topic and would be willing to help out in any form
> desired: either by contributing to Joe's work here or, if deemed more
> feasible, to start out completely new from scratch -- dependent on your
> opinion on the proposed, more minimal approach as well as on Joe's plans
> around klp-convert.
> 
> Looking forward to hearing your feedback!

So guys, any feedback? Ping :)

> 
> Thanks,
> 
> Nicolai
> 
> (*) We've been experimenting with building the relocation records
>     manually by various means, e.g. with GNU as' .reloc directive as an
>     example, but this all turned out impractical for various
>     reasons. Most noteworthy, because the records' offsets wouldn't get
>     adjusted properly when linking AFAIR.
> 
> (**) by some other means than directly with kpatch-build
> 
> -- 
> SUSE Software Solutions Germany GmbH, Frankenstra?e 146, 90461 N?rnberg, Germany
> GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
> (HRB 36809, AG N?rnberg)