Re: [RFC] Add target module check before livepatch module loading

[Petr Mladek <pmladek@suse.com>]

On Tue 2025-03-11 11:53:59, zhang warden wrote:
> > A single livepatch could modify more objects: vmlinux and several
> > modules. The metadata for each modified object are in "struct
> > klp_object". The related obect is currently identified only by obj->name.
> > And we could add more precision identification by setting
> > also "obj->srcversion" and/or "obj->build_id".
> > 
> 
> Yep, but how can we get the obj->srcversion? If we tring to store it 
> in klp_object, the information should be carried when livepatch is being build.
> Otherwise, we don't know which srcversion is good to patch, isn't it?

I am not sure if I get the question correctly.

Anyway, struct klp_object must be defined in any livepatch, for example, see
/prace/kernel/linux/samples/livepatch/livepatch-sample.c

I guess that you are using kPatch. I am not sure how it initializes
these klp_patch, klp_object, and klp_func structures.
But it has to create struct klp_object for the livepatched module
and initialize at least .name, .func items.

The srcversion of the livepatched module can be read by modinfo,
for example:

# modinfo test_printf
filename:       /lib/modules/6.13.0-default+/kernel/lib/test_printf.ko
license:        GPL
description:    Test cases for printf facility
author:         Rasmus Villemoes <linux@rasmusvillemoes.dk>
test:           Y
srcversion:     AF319FC942A3220645E7E99
depends:        
intree:         Y
name:           test_printf
retpoline:      Y
vermagic:       6.13.0-default+ SMP preempt mod_unload modversions 

You need to teach kPatch to read the srcversion of the livepatched
module and set it in the related struct klp_object.

Best Regards,
Petr