Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm

Nicholas Piggin
2016-12-09T08:15:17Z

On Fri, 9 Dec 2016 08:55:51 +0100
Stanislav Kozina <skozina@redhat.com> wrote:

> >> The question is how to provide a similar guarantee if a different way?
> > As a tool to aid distro reviewers, modversions has some value, but the
> > debug info parsing tools that have been mentioned in this thread seem
> > superior (not that I've tested them).
>
> On the other hand the big advantage of modversions is that it also
> verifies the checksum during runtime (module loading). In other words, I
> believe that any other solution should still generate some form of
> checksum/watermark which can be easily checked for compatibility on
> module load.
> It should not be hard to add to the DWARF based tools though. We'd just
> parse DWARF data instead of the C code.

A runtime check is still done, with per-module vermagic which distros
can change when they bump the ABI version. Is it really necessary to
have more than that (i.e., per-symbol versioning)?

Thanks,
Nick