Re: Another unwinding problem on ARM

[Mathias Bauer]

Hi,

please review and perhaps apply the attached patch.

Thanks and best regards,
Mathias

Am 14.03.14 13:56, schrieb Mathias Bauer:
> Hi,
>
> once you find it, the solution quite often is easy. :-)
>
> The culprit was that unwind-arm.h in libobjc2 can't cope with unwind
> states that have been "or-ed" with _US_FORCE_UNWIND.
>
> Defining it in this file and replacing
>
> switch(state)
>
> with
>
> switch(state & ~_US_FORCE_UNWIND)
>
> helps.
>
> Without that, the PR wrapper in this header file always returns
> _URC_FAILURE. I overlooked that in the first place because I only looked
> whether internal_objc_personality was called.
>
> Now the test case works - at least when run inside gdb. I still have to
> find out why it core dumps without gdb.
>
> Regards,
> Mathias
>
>
> Am 14.03.14 02:15, schrieb David Chisnall:
> > On 14 Mar 2014, at 07:50, Mathias Bauer <mathias_bauer@gmx.net> wrote:
> >
> > > This time again standard PRs in libgcc are used 4 times, but then a
> > > different PR is used. This PR does  return neither INSTALL_CONTEXT
> > > nor CONTINUE_UNWIND, thus the unwind function returns to
> > > pthread_exit, causing the app to abort.
> >
> > Do you know what the personality routine that is being invoked is?
> >
> > > The PR is taken from the EHT of that frame. The offset points into
> > > libgnustepbase, the PR of the Objective-C runtime is not called.
> > > OTOH in the same test case on Linux X86_64 the PR in libobjc2 *is*
> > > called at this point. Is it possible that there is still something
> > > funky in the EHT entries of Objective-C code?
> >
> > We should be using the C personality routine for frames that don't
> > have any Objective-C @try blocks or C++ try blocks, but do have
> > cleanups, so that's not necessarily wrong...
> >
> > David
> >
> > -- Sent from my IBM 1620
>
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unwind-arm.diff
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