From: Nicholas Piggin <npiggin@gmail.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Dodji Seketeli <dodji@seketeli.org>,
Ian Campbell <ijc@hellion.org.uk>, Michal Marek <mmarek@suse.com>,
Ben Hutchings <ben@decadent.org.uk>,
Linus Torvalds <torvalds@linux-foundation.org>,
Adam Borowski <kilobyte@angband.pl>,
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>,
Stanislav Kozina <skozina@redhat.com>
Subject: Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm
Date: Mon, 12 Dec 2016 13:50:06 +1000 [thread overview]
Message-ID: <20161212135006.58fb9d8e@roar.ozlabs.ibm.com> (raw)
In-Reply-To: <20161210124103.GD21421@kroah.com>
On Sat, 10 Dec 2016 13:41:03 +0100
Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> On Fri, Dec 09, 2016 at 11:46:54PM +0100, Dodji Seketeli wrote:
> > Hello,
> >
> > Nicholas Piggin <npiggin@gmail.com> a écrit:
> >
> > [...]
> >
> > > That said, a dwarf based checker tool should be able to do as good a job
> > > (maybe a bit better because report is very informative and it may pick up
> > > compiler alignments or padding options).
> >
> > So, Nicholas was kind enough to send me the two Linux Kernel binaries
> > that he built with the tiny little interface change that we were
> > discussing earlier. Here is what the abidiff[1] tools says about that
> > interface change:
> >
> > $ time ~/git/libabigail/kabidiff/build/tools/abidiff vmlinux.abi1.abi vmlinux.abi2.abi
> > Functions changes summary: 0 Removed, 1 Changed, 0 Added function
> > Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
> >
> > 1 function with some indirect sub-type change:
> >
> > [C]'function int foo(blah*)' at memory.c:82:1 has some indirect sub-type changes:
> > parameter 1 of type 'blah*' has sub-type changes:
> > in pointed to type 'struct blah' at memory.c:78:1:
> > type size changed from 32 to 64 bits
> > 1 data member insertion:
> > 'int blah::y', at offset 0 (in bits) at memory.c:79:1
> > 1 data member change:
> > 'int blah::x' offset changed from 0 to 32 (in bits) (by +32 bits)
> >
> >
> >
> > real 0m2.595s
> > user 0m2.489s
> > sys 0m0.108s
> > $
> >
> > I kept the timing information to give you an idea of the time it takes
> > on a non-optimized build of abidiff.
> >
> > One could for instance want that types that are not defined in header
> > files be kept out of the change report. In that case it's possible to
> > write a little suppression specification file like this one:
> >
> > $ cat vmlinux.abignore
> > [suppress_type]
> > source_location_not_regexp = .*\\.h
> > $
> >
> > You can then pass that suppression file to the tool:
> >
> > $ ~/git/libabigail/kabidiff/build/tools/abidiff --suppr vmlinux.abignore vmlinux.abi1.abi vmlinux.abi2.abi
> > Functions changes summary: 0 Removed, 0 Changed (1 filtered out), 0 Added function
> > Variables changes summary: 0 Removed, 0 Changed, 0 Added variable
> >
> >
> > real 0m2.574s
> > user 0m2.473s
> > sys 0m0.102s
> > $
> >
> > So this is the kind of interface change analysis tool we are working on
> > at the moment.
> >
> > One could also imagine a tool that would compute a CRC that takes the
> > very same suppression specification files into account, letting people
> > to decide that some interface changes are OK. That CRC would thus be
> > added to the special ELF sections we already have today. We could keep
> > the modversion machinery, but with a greater dose of flexibility.
> > Whenever modversion detects a change, abidiff would tell people what the
> > change is exactly.
> >
> > What do you guys think?
>
> YES YES YES!!!
>
> Now I don't work on a distro anymore, but I would think that something
> like this would be really useful, pointing out exactly what changed is
> very important for distro maintainers to determine what they want to do
> (either fix up the abi change with strange hacks, or ignore it due to
> the change being in an area they don't care at all about, i.e. a random
> driver subsystem.)
>
> So yes, I think this is really good stuff. But if the distro
> maintainers correct me and think it's useless, then I need to revisit my
> view of exactly what they do for their customers :)
Agree completely. BTW (for those who might be looking into these tools),
we also have https://github.com/skozina/kabi-dw that Stanislav (cc'ed)
mentioned earlier.
It's true that the current modversions __crc_ matching infrastructure is
"just" a symbol versioning system, and we could keep it and just populate
it with something other than genksyms (e.g., a symbol version list provided
by distros). But the starting point should be *no* versioning and simply
using names to break linkage. Unless there's a compelling reason not to,
symbols are simpler, easier, everyone knows how they work.
The other question would be whether to pull a minimal tool into the kernel
source or keep them out of tree (but possibly add some helper scripts etc).
I guess we'll need to see what distros want.
Thanks,
Nick
next prev parent reply other threads:[~2016-12-12 3:50 UTC|newest]
Thread overview: 113+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <a73aec83-ddad-2bdf-e612-178c9936a16f@manjaro.org>
[not found] ` <20161102004639.6870806d@roar.ozlabs.ibm.com>
2016-11-23 20:08 ` BUG: 4.9-rc6 Still "no symbol version" on boot Philip Müller
2016-11-23 20:14 ` Robert LeBlanc
2016-11-23 20:27 ` Philip Müller
2016-11-23 20:53 ` Adam Borowski
2016-11-23 21:01 ` Robert LeBlanc
2016-11-23 21:02 ` [PATCH] x86/kbuild: enable modversions for symbols exported from asm Adam Borowski
2016-11-23 23:10 ` Philip Müller
2016-11-24 4:40 ` Ingo Molnar
2016-11-24 5:20 ` Nicholas Piggin
2016-11-24 6:00 ` Ingo Molnar
2016-11-24 7:20 ` Nicholas Piggin
2016-11-24 7:36 ` Greg Kroah-Hartman
2016-11-24 7:53 ` Nicholas Piggin
2016-11-24 9:32 ` Michal Marek
2016-11-24 10:03 ` Nicholas Piggin
2016-11-24 10:51 ` Michal Marek
2016-11-24 9:38 ` Arnd Bergmann
2016-11-24 10:01 ` Nicholas Piggin
2016-11-24 9:56 ` Greg Kroah-Hartman
2016-11-24 10:31 ` Nicholas Piggin
2016-11-24 15:24 ` Greg Kroah-Hartman
2016-11-25 0:40 ` Nicholas Piggin
2016-11-25 18:00 ` Linus Torvalds
2016-11-26 0:37 ` Nicholas Piggin
2016-11-29 1:15 ` Ben Hutchings
2016-11-29 2:31 ` Nicholas Piggin
2016-11-29 9:14 ` Michal Marek
2016-11-29 4:08 ` Linus Torvalds
2016-11-29 13:19 ` Adam Borowski
2016-11-29 13:29 ` Ingo Molnar
2016-11-29 14:24 ` Adam Borowski
2016-11-29 13:51 ` Adam Borowski
[not found] ` <CA+55aFyZiB4YkwvqzrXO=HD8bcnc2xHkAYrek2QHVnhVvAi3Fw@mail.gmail.com>
2016-11-29 16:03 ` Michal Marek
2016-11-29 16:17 ` Linus Torvalds
2016-11-29 19:57 ` Ben Hutchings
2016-11-29 20:35 ` Linus Torvalds
2016-11-30 18:18 ` Nicholas Piggin
2016-11-30 18:40 ` Linus Torvalds
2016-11-30 21:33 ` Ben Hutchings
2016-12-01 1:55 ` Nicholas Piggin
2016-12-01 2:35 ` Ben Hutchings
2016-12-01 3:39 ` Nicholas Piggin
2016-12-01 16:12 ` Michal Marek
2016-12-02 14:36 ` Hannes Frederic Sowa
2016-12-09 3:33 ` Nicholas Piggin
2016-12-09 15:21 ` Ian Campbell
2016-12-09 16:15 ` Nicholas Piggin
2016-12-09 22:46 ` Dodji Seketeli
2016-12-10 12:41 ` Greg Kroah-Hartman
2016-12-12 3:50 ` Nicholas Piggin [this message]
2016-12-12 9:08 ` Ian Campbell
2016-12-14 17:59 ` Don Zickus
2016-12-13 1:07 ` Stanislav Kozina
2016-12-13 22:51 ` Michal Marek
2016-12-14 8:58 ` Dodji Seketeli
2016-12-14 9:15 ` Michal Marek
2016-12-14 9:36 ` Dodji Seketeli
2016-12-14 9:44 ` Michal Marek
2016-12-14 10:02 ` Dodji Seketeli
2016-12-14 10:15 ` Michal Marek
2016-12-14 9:56 ` Dodji Seketeli
2016-12-14 9:37 ` Michal Marek
2016-12-01 4:13 ` Don Zickus
2016-12-01 4:32 ` Nicholas Piggin
2016-12-01 15:20 ` Don Zickus
2016-12-01 15:26 ` Christoph Hellwig
2016-12-01 15:40 ` Don Zickus
2016-12-01 16:06 ` Greg Kroah-Hartman
2016-12-01 18:42 ` Don Zickus
2016-12-09 3:50 ` Nicholas Piggin
2016-12-09 7:55 ` Stanislav Kozina
2016-12-09 8:14 ` Nicholas Piggin
2016-12-09 14:36 ` Stanislav Kozina
2016-12-09 15:56 ` Nicholas Piggin
2016-12-09 16:03 ` Greg Kroah-Hartman
2016-12-12 9:48 ` Stanislav Kozina
2016-12-13 7:25 ` Nicholas Piggin
2016-12-14 14:04 ` Hannes Frederic Sowa
2016-12-15 2:06 ` Nicholas Piggin
2016-12-15 11:19 ` Hannes Frederic Sowa
2016-12-15 12:03 ` Nicholas Piggin
2016-12-15 13:15 ` Hannes Frederic Sowa
2016-12-15 14:15 ` Nicholas Piggin
2016-12-15 15:17 ` Hannes Frederic Sowa
2016-12-15 13:35 ` Stanislav Kozina
2016-12-09 16:16 ` Don Zickus
2016-12-01 10:48 ` Stanislav Kozina
2016-12-01 11:09 ` Nicholas Piggin
2016-12-01 11:33 ` Stanislav Kozina
2016-12-01 12:39 ` Nicholas Piggin
2016-12-01 15:19 ` Dodji Seketeli
2016-12-01 16:14 ` Michal Marek
2016-11-29 17:05 ` Adam Borowski
2016-11-29 17:10 ` Linus Torvalds
2016-11-29 17:14 ` Linus Torvalds
2016-12-01 13:58 ` Arnd Bergmann
2016-12-01 16:21 ` Michal Marek
2016-12-01 18:26 ` Linus Torvalds
2016-12-02 10:55 ` Arnd Bergmann
2016-12-02 12:40 ` [RFC, PATCH, v3.9] default exported asm symbols to zero Arnd Bergmann
2016-12-02 12:59 ` Geert Uytterhoeven
2016-12-02 14:51 ` Arnd Bergmann
2016-12-02 15:35 ` Adam Borowski
2016-12-03 4:36 ` Ben Hutchings
2016-12-03 10:43 ` Arnd Bergmann
2016-12-02 17:04 ` [PATCH] x86/kbuild: enable modversions for symbols exported from asm Linus Torvalds
2016-12-04 7:44 ` Alan Modra
2016-12-04 20:44 ` Linus Torvalds
2016-11-29 21:23 ` Michal Marek
2016-11-24 9:25 ` Michal Marek
2016-11-24 11:42 ` Regression: " Kalle Valo
2016-11-23 23:07 ` BUG: 4.9-rc6 Still "no symbol version" on boot Philip Müller
2016-11-28 17:10 ` Robert LeBlanc
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