Re: Possibly wrong address passed to callq asm instruction within MPIR test binaries

[Corinna Vinschen <corinna-cygwin at cygwin dot com>]

On Apr  2 00:07, Jean-Pierre Flori wrote:
> Dear all,
> 
> It's amazing to see how well Cygwin64 is going.
> Thanks for your hard work.
> 
> While preparing the new MPIR release, which will be the first one to
> support Cygwin4, we encountered problems running MPIR testsuite when
> MPIR was configured to produce a shared lib.
> That's with latest cygwin/binutils/gcc/g++ from today.
> 
> It seems that a call to the MPN_ZERO macro, which on my setup is at
> 0x4ff2746c0 in the shared lib but we get the instruction:
> callq 0xff2746c0

This looks suspicious.  On x86_64 this kind of instruction is usually
PC-relative or uses a jump table, because x86_64 uses the small code
model by default (medium model on Cygwin).

> within the test binary and that yields a nice segfault.
> Please see https://groups.google.com/d/msg/mpir-devel/KzsxIWhVx8A/EAUoP4ybWOMJ
> and the few following post for more details.
> 
> For sure, we don't get what's going on here.
> Would you have any clue?

Not without a more detailed report.  The aforementioned link does not
contain pointers to the source, for instance.  Also, a simple testcase
might be helpful.

If you suspect a linker bug, you might contemplate to ask on the
binutils mailing list binutils AT sourceware DOT org which is where ld
is maintained.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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