linux-kernel - Re: [PATCH v4 15/16] module: Move where we mark modules RO,X

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Message-ID: <20191022123112.GI1800@hirez.programming.kicks-ass.net>
Date:   Tue, 22 Oct 2019 14:31:12 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Heiko Carstens <heiko.carstens@...ibm.com>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, rostedt@...dmis.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, jeyu@...nel.org
Subject: Re: [PATCH v4 15/16] module: Move where we mark modules RO,X

On Tue, Oct 22, 2019 at 01:31:16PM +0200, Heiko Carstens wrote:
> On Mon, Oct 21, 2019 at 06:11:35PM +0200, Peter Zijlstra wrote:
> > On Mon, Oct 21, 2019 at 05:34:25PM +0200, Peter Zijlstra wrote:
> > > On Mon, Oct 21, 2019 at 04:14:02PM +0200, Peter Zijlstra wrote:
> > 
> > > So On IRC Josh suggested we use text_poke() for RELA. Since KLP is only
> > > available on Power and x86, and Power does not have STRICT_MODULE_RWX,
> > > the below should be sufficient.
> > > 
> > > Completely untested...
> > 
> > And because s390 also has: HAVE_LIVEPATCH and STRICT_MODULE_RWX the even
> > less tested s390 bits included below.
> > 
> > Heiko, apologies if I completely wrecked it.
> > 
> > The purpose is to remove module_disable_ro()/module_enable_ro() from
> > livepatch/core.c such that:
> > 
> >  - nothing relies on where in the module loading path module text goes RX.
> >  - nothing ever has writable text
> 
> Given that Steven reported a crash, I assume I can wait until you
> repost a new version of the series, which also includes s390 bits?

His crash is somewhat orthogonal, but yes, I will repost once sorted.