From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1IVgDL-0005IV-TS
	for qemu-devel@nongnu.org; Thu, 13 Sep 2007 00:22:03 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1IVgDJ-0005I6-Gg
	for qemu-devel@nongnu.org; Thu, 13 Sep 2007 00:22:02 -0400
Received: from [199.232.76.173] (helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1IVgDJ-0005I3-9l
	for qemu-devel@nongnu.org; Thu, 13 Sep 2007 00:22:01 -0400
Received: from phoenix.bawue.net ([193.7.176.60] helo=mail.bawue.net)
	by monty-python.gnu.org with esmtps
	(TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60)
	(envelope-from <ths@networkno.de>) id 1IVgDJ-0007zK-0N
	for qemu-devel@nongnu.org; Thu, 13 Sep 2007 00:22:01 -0400
Date: Thu, 13 Sep 2007 05:21:58 +0100
From: Thiemo Seufer <ths@networkno.de>
Subject: Re: [Qemu-devel] [PATCH] S/390 host fixed
Message-ID: <20070913042158.GE15247@networkno.de>
References: <200707301349.26745.uli@suse.de> <200707301605.47719.uli@suse.de>
	<20070731235915.GL26960@networkno.de>
	<200708011544.43401.uli@suse.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <200708011544.43401.uli@suse.de>
Reply-To: qemu-devel@nongnu.org
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Ulrich Hecht <uli@suse.de>
Cc: qemu-devel@nongnu.org

Ulrich Hecht wrote:
[snip]
> > > +#ifdef __s390__
> > > +    retaddr = (void*)((unsigned long)retaddr & 0x7fffffffUL);
> > > +#endif
> >
> > All of those look weird. Is this a null-extension vs. sign-extension
> > issue?
> 
> S/390 has a 31 (thirty-one) bit address space; the MSB of the PSW is not 
> part of the address and must be masked out. This is simply part of the 
> architecture, there's no way around it.

It looks like the retaddr value is always acquired via the GETPC macro,
which does a __builtin_return_address(0). Could you check that
 - Gcc's __builtin_return_address isn't just broken
 - If the compiler is ok, test if twiddling the bit in the GETPC macro
   works for s390. I suspect this catches more instances of the problem
   and might even explain the odd breakage you saw.

> > > +#ifdef __s390__
> > > +            func = NULL; /* does not work on S/390 for unknown
> > > reasons */ +#else
> > >              func = gen_jcc_sub[s->cc_op - CC_OP_SUBB][jcc_op];
> > > +#endif
> >
> > Hum. It wold be good to know what happens here.
> 
> Indeed. :)


Thiemo