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Date:   Mon, 21 Oct 2019 08:53:12 -0500
From:   Josh Poimboeuf <jpoimboe@redhat.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org,
        mhiramat@kernel.org, bristot@redhat.com, jbaron@akamai.com,
        torvalds@linux-foundation.org, tglx@linutronix.de,
        mingo@kernel.org, namit@vmware.com, hpa@zytor.com, luto@kernel.org,
        ard.biesheuvel@linaro.org, jeyu@kernel.org
Subject: Re: [PATCH v4 15/16] module: Move where we mark modules RO,X
Message-ID: <20191021135312.jbbxsuipxldocdjk@treble>
References: <20191018073525.768931536@infradead.org>
 <20191018074634.801435443@infradead.org>
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On Fri, Oct 18, 2019 at 09:35:40AM +0200, Peter Zijlstra wrote:
> Now that set_all_modules_text_*() is gone, nothing depends on the
> relation between ->state =3D COMING and the protection state anymore.
> This enables moving the protection changes later, such that the COMING
> notifier callbacks can more easily modify the text.
>=20
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Cc: Jessica Yu <jeyu@kernel.org>
> ---
>  kernel/module.c |    8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>=20
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -3683,10 +3683,6 @@ static int complete_formation(struct mod
>  =09/* This relies on module_mutex for list integrity. */
>  =09module_bug_finalize(info->hdr, info->sechdrs, mod);
> =20
> -=09module_enable_ro(mod, false);
> -=09module_enable_nx(mod);
> -=09module_enable_x(mod);
> -
>  =09/* Mark state as coming so strong_try_module_get() ignores us,
>  =09 * but kallsyms etc. can see us. */
>  =09mod->state =3D MODULE_STATE_COMING;
> @@ -3852,6 +3848,10 @@ static int load_module(struct load_info
>  =09if (err)
>  =09=09goto bug_cleanup;
> =20
> +=09module_enable_ro(mod, false);
> +=09module_enable_nx(mod);
> +=09module_enable_x(mod);
> +
>  =09/* Module is ready to execute: parsing args may do that. */
>  =09after_dashes =3D parse_args(mod->name, mod->args, mod->kp, mod->num_k=
p,
>  =09=09=09=09  -32768, 32767, mod,

[ Sorry if this was already discussed, I still have a large backlog. ]

Doesn't livepatch code also need to be modified?  We have:

prepare_coming_module()
=09klp_module_coming()
=09=09klp_init_object_loaded()
=09=09=09module_disable_ro()
=09=09=09...
=09=09=09module_enable_ro()

which is done right before the above patch does module_enable_ro().

We could remove the disable-RO from that case, though we'd still need it
for another case (late module patching).

--=20
Josh