From: Guenter Roeck <linux@roeck-us.net>
To: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
lkml <linux-kernel@vger.kernel.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
linux-next <linux-next@vger.kernel.org>
Subject: Re: [PATCH 0/2] Tentative fix for the divide-by-zero on score/paris/..
Date: Wed, 15 Apr 2015 08:31:50 -0700 [thread overview]
Message-ID: <20150415153150.GA1149@roeck-us.net> (raw)
In-Reply-To: <20150415134637.GB5947@chrystal.uk.oracle.com>
On Wed, Apr 15, 2015 at 03:46:37PM +0200, Quentin Casasnovas wrote:
> On Wed, Apr 15, 2015 at 06:26:58AM -0700, Guenter Roeck wrote:
> > On 04/15/2015 01:54 AM, Quentin Casasnovas wrote:
> > >
> > > Let me know if this makes things better..
> > >
>
> Hi Guenter,
>
> >
> > the crash is fixed, but now I get
> >
>
> That's a first step.. :)
>
> > FATAL: The relocation at __ex_table+0x4 references
> > [...]
> >
> > for parisc:defconfig,
> > for score:allnoconfig, and
> > for mn10300:defconfig.
>
> Thanks for the testing, much appreciated!
>
> >
> > While I agree that those should get fixed (if they are real problems,
> > especially the ones for parisc and mn10300), I don't think it is
> > a good idea to fail the build because of it.
>
> That's a tough one.. I think it's pretty bad in general to have some
> crufts in the ex_table referencing non-executable sections. Note that it
> will not make the build fail if the relocation _seems_ legit (jump to an
> executable section even though it's not part of the white-list) but in
> those cases, something really does look wrong and could potentially have a
> security impact so I thought the build failure was a good thing to do.
>
Hi Quentin,
Guess we have a different philosophy; mine is "do no harm".
> Now, if it's a problem in modpost (which is likely!), then obviously I'd be
> happy to try and help fix that!
>
> >
> > Note that I did find the problem in the score build; that was a real bug.
> > I don't know what may be wrong with the others.
>
> Cool! Mind CC'ing me to your fix, I'm curious :)
>
I'll do that.
> Regarding the others, if you've compiled them with debug information, you
> should be able to do some addr2line magic incantation to find the offending
> code. I've also added scripts/check_extable.sh which you might be able to
> use to get more details about the failures (or simply use the same logic in
> there to know where those maybe-wrong-relocations are coming from).
>
> I'm surprised/concerned that some sections appear to have no name though
> (indicating yet another bug in my modpost changes?).. If you can share the
> object files then I can have a look (and possibly help with the addr2line
> incantation).
>
I don't really have time to do that; please keep in mind that I am not getting
paid for this and do it in my free time. Both the parisc and mn10300 (am33)
tool chains are available from kernel.org; it should be straightforward to
install them and see yourself what is going on. Unlike score I did not find
the problem in those architectures with code inspection.
Thanks,
Guenter
next prev parent reply other threads:[~2015-04-15 15:32 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-14 8:42 linux-next: Tree for Apr 14 Stephen Rothwell
2015-04-14 16:11 ` linux-next: Tree for Apr 14 (crash due to modpost patch) Guenter Roeck
2015-04-14 16:36 ` Quentin Casasnovas
2015-04-14 16:50 ` Guenter Roeck
2015-04-15 8:54 ` [PATCH 0/2] Tentative fix for the divide-by-zero on score/paris/ Quentin Casasnovas
2015-04-15 8:54 ` [PATCH 1/2] modpost: fix inverted logic in is_extable_fault_address() Quentin Casasnovas
2015-04-15 8:54 ` [PATCH 2/2] modpost: fix extable entry size calculation Quentin Casasnovas
2015-04-15 13:26 ` [PATCH 0/2] Tentative fix for the divide-by-zero on score/paris/ Guenter Roeck
2015-04-15 13:46 ` Quentin Casasnovas
2015-04-15 15:31 ` Guenter Roeck [this message]
2015-04-15 16:49 ` Quentin Casasnovas
2015-04-15 21:19 ` Quentin Casasnovas
2015-04-15 21:32 ` Guenter Roeck
2015-04-16 1:43 ` Guenter Roeck
2015-04-16 3:49 ` Rusty Russell
2015-04-16 8:21 ` Quentin Casasnovas
2015-04-16 12:47 ` Guenter Roeck
2015-04-16 13:58 ` Quentin Casasnovas
2015-04-18 5:52 ` Guenter Roeck
2015-04-19 11:47 ` Quentin Casasnovas
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