linux-kernel - Re: [PATCH v3 5/6] x86/ftrace: Use text

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Message-ID: <20191015153120.GA21580@linux-8ccs>
Date:   Tue, 15 Oct 2019 17:31:20 +0200
From:   Jessica Yu <jeyu@...nel.org>
To:     Joe Lawrence <joe.lawrence@...hat.com>
Cc:     Miroslav Benes <mbenes@...e.cz>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org, mhiramat@...nel.org,
        bristot@...hat.com, jbaron@...mai.com,
        torvalds@...ux-foundation.org, tglx@...utronix.de,
        mingo@...nel.org, namit@...are.com, hpa@...or.com, luto@...nel.org,
        ard.biesheuvel@...aro.org, jpoimboe@...hat.com,
        live-patching@...r.kernel.org
Subject: Re: [PATCH v3 5/6] x86/ftrace: Use text_poke()

+++ Joe Lawrence [15/10/19 11:06 -0400]:
>On 10/15/19 10:13 AM, Miroslav Benes wrote:
>>Yes, it does. klp_module_coming() calls module_disable_ro() on all
>>patching modules which patch the coming module in order to call
>>apply_relocate_add(). New (patching) code for a module can be relocated
>>only when the relevant module is loaded.
>
>FWIW, would the LPC blue-sky2 model (ie, Steve's suggestion @ 
>plumber's where livepatches only patch a single object and updates are 
>kept on disk to handle coming module updates as they are loaded) 
>eliminate those outstanding relocations and the need to perform this 
>late permission flipping?

I wasn't at Plumbers sadly, was this idea documented/talked about in
detail somewhere? (recording, slides, etherpad, etc?). What do you
mean by updates are kept on disk? Maybe someone can explain it more
in detail? :)