Hello,

On Thu, 7 Dec 2017 13:55:07 +0100
Martin Schwidefsky <schwidefsky@de.ibm.com> wrote:

> On Thu,  7 Dec 2017 11:37:27 +0100
> Michal Suchanek <msuchanek@suse.de> wrote:
> 
> > Fix following error:
> > 
> >   LD      arch/s390/boot/compressed/vmlinux
> > drivers/s390/char/sclp_early_core.o: In function `memcpy':
> > ../include/linux/string.h:340: undefined reference to
> > `fortify_panic' make[4]: ***
> > [../arch/s390/boot/compressed/Makefile:29:
> > arch/s390/boot/compressed/vmlinux] Error 1
> > 
> > Fixes: 79962038dffa ("s390: add support for FORTIFY_SOURCE")
> > Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> > ---
> >  arch/s390/boot/compressed/misc.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/arch/s390/boot/compressed/misc.c
> > b/arch/s390/boot/compressed/misc.c index cecf38b9ec82..e79c4499c548
> > 100644 --- a/arch/s390/boot/compressed/misc.c
> > +++ b/arch/s390/boot/compressed/misc.c
> > @@ -174,3 +174,7 @@ unsigned long decompress_kernel(void)
> >  	return (unsigned long) output;
> >  }
> > 
> > +void fortify_panic(const char *name)
> > +{
> > +	error("detected buffer overflow");
> > +}  
> 
> Odd, the current linux master tree builds just fine with
> CONFIG_FORTIFY_SOURCE=y. There *is* a reference to fortify_panic in
> drivers/s390/char/sclp_early.o. This object is included in the link
> for the compressed vmlinux, but the function  that contains the call
> to fortify_panic is not included in the compressed image. I wonder
> what causes this difference in behavior.
> 
> The patch makes sense though and I will add it to the queue.
> 

It probably depends on the config.

FWIW attaching the config that fails to build for me.

Thanks

Michal