Re: objtool segfault with ORC unwinder enabled

Markus
2018-01-03T14:36:29Z

On Wed, Jan 03, 2018 15:14:01 CET Greg Kroah-Hartman wrote:
> On Wed, Jan 03, 2018 at 01:22:07PM +0100, Markus wrote:
> > On Wed, Jan 03, 2018 at 12:19:41 CET Greg Kroah-Hartman wrote:
> > > On Wed, Jan 03, 2018 at 11:49:08AM +0100, Markus wrote:
> > > > Hello!
> > > >
> > > > ORC unwinder is enabled in stable for wider testing but still at least
> > > > one
> > > > bug is open:
> > > > https://bugzilla.kernel.org/show_bug.cgi?id=197035
> > >
> > > Random web links on mailing lists don't help much, please put the
> > > information here in the email.
> >
> > Its not a random web link. Its the official kernel.org bugtracker. But
> > nobody seems to be looking at it.
>
> Not all subsystems use bugzilla.kernel.org, sorry. Email is the
> preferred way for almost all subsystems.
>
> > > > objtool will segfault because a NULL pointer is dereferenced.
> > >
> > > And how are you reproducing this?
> >
> > Just building the kernel with ORC enabled.
> > (At least for me. Using framepointers compiles, enabling ORC again breaks
> > it.) gcc 6.4.0 (In bug report others were tested as well.)
> > elfutils 0.170
> > What else may be interesting?
>
> Have you tried gcc 7?

No I have no gcc 7 installed, yet. (In the bug report gcc 8.0.0 and gcc 5.4.0
were mentioned.)

> What distro is this? Hopefully not hardened Gentoo? :)

Just a normal gentoo.

> > > > Is a NULL pointer sym valid?
> > > > If a NULL pointer is invalid, it has to be checked why it is sometimes
> > > > NULL.
> > >
> > > What .config is triggering this problem?
> >
> > See attachment.
> >
> > > And does this show up on 4.14.11, and 4.15-rc6?
> >
> > Both: yes.
> >
> > /tools/objtool/objtool orc generate --no-fp "arch/x86/kernel/irq.o"
> >
> > => segfault.
>
> Ugh, I can't duplicate here :(

How about the previously attached irq.o?

BR,
Markus