Re: [PATCH 6/7] livepatch: Remove module_disable_ro() usage

[Jessica Yu]

+++ Josh Poimboeuf [14/04/20 11:28 -0500]:
> With arch_klp_init_object_loaded() gone, and apply_relocate_add() now
> using text_poke(), livepatch no longer needs to use module_disable_ro().
>
> The text_mutex usage can also be removed -- its purpose was to protect
> against module permission change races.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> ---
> kernel/livepatch/core.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index 817676caddee..3a88639b3326 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -767,10 +767,6 @@ static int klp_init_object_loaded(struct klp_patch *patch,
> 	struct klp_modinfo *info = patch->mod->klp_info;
>
> 	if (klp_is_module(obj)) {
> -
> -		mutex_lock(&text_mutex);
> -		module_disable_ro(patch->mod);
> -

Don't you still need the text_mutex to use text_poke() though?
(Through klp_write_relocations -> apply_relocate_add -> text_poke)
At least, I see this assertion there:

void *text_poke(void *addr, const void *opcode, size_t len)
{
	lockdep_assert_held(&text_mutex);

	return __text_poke(addr, opcode, len);
}

Jessica