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

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Message-ID: <88bab814-ea24-ece9-2bc0-7a1e10a62f12@redhat.com>
Date:   Tue, 15 Oct 2019 11:06:53 -0400
From:   Joe Lawrence <joe.lawrence@...hat.com>
To:     Miroslav Benes <mbenes@...e.cz>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Jessica Yu <jeyu@...nel.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()

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?

-- Joe