Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm
- To: Stanislav Kozina <skozina@redhat.com>
- Cc: Don Zickus <dzickus@redhat.com>, Linus Torvalds <torvalds@linux-foundation.org>, Ben Hutchings <ben@decadent.org.uk>, Michal Marek <mmarek@suse.com>, Adam Borowski <kilobyte@angband.pl>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>, Debian kernel maintainers <debian-kernel@lists.debian.org>, "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>, Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
- Subject: Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm
- From: Nicholas Piggin <npiggin@gmail.com>
- Date: Fri, 9 Dec 2016 18:14:59 +1000
- Message-id: <[🔎] 20161209181459.1f0a4fed@roar.ozlabs.ibm.com>
- In-reply-to: <[🔎] 0937c184-1946-c494-56b6-c38fd0b632c2@redhat.com>
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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
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