From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:51717)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <benh@kernel.crashing.org>) id 1bRndt-0000gq-JR
	for qemu-devel@nongnu.org; Mon, 25 Jul 2016 17:42:30 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <benh@kernel.crashing.org>) id 1bRndp-0003dz-Bh
	for qemu-devel@nongnu.org; Mon, 25 Jul 2016 17:42:28 -0400
Received: from gate.crashing.org ([63.228.1.57]:49570)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <benh@kernel.crashing.org>) id 1bRndp-0003c6-13
	for qemu-devel@nongnu.org; Mon, 25 Jul 2016 17:42:25 -0400
Message-ID: <1469482923.5978.54.camel@kernel.crashing.org>
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Tue, 26 Jul 2016 07:42:03 +1000
In-Reply-To: <b15faa79-7481-5265-f145-e2254d4c7dfa@twiddle.net>
References: <1469364141.8568.251.camel@kernel.crashing.org>
	<1469364697.8568.253.camel@kernel.crashing.org>
	<1469364745.8568.254.camel@kernel.crashing.org>
	<5eede4b0-cc3a-c24f-5de4-8473220385f9@twiddle.net>
	<1469407593.8568.265.camel@kernel.crashing.org>
	<1469407897.8568.268.camel@kernel.crashing.org>
	<b15faa79-7481-5265-f145-e2254d4c7dfa@twiddle.net>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Subject: Re: [Qemu-devel] TCG problem with cpu_{st,ld}x_data ?
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel/>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Richard Henderson <rth@twiddle.net>, qemu-devel@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Christian Borntraeger <borntraeger@de.ibm.com>

On Mon, 2016-07-25 at 19:30 +0530, Richard Henderson wrote:
> > Or can they also be called outside of that context ?
>=20
> No, not without a valid return address.
>=20
> E.g. it's not valid to have one helper call another, and for the second=
 helper=C2=A0
> use GETPC.=C2=A0 For this, typically, one must factor out a common func=
tion which=C2=A0
> accepts a "retaddr" argument, which the callers must fill in with GETPC.

Right, I've figured that out. I notice that the cpu_ldl_code() are
sprinkled in parts that are "chancy".

For example we have one in powerpc_excp() to read the faulting
instruction, though that *should* never fail it's till not great.

I haven't completely figured out what code path instruction translation
faults take, I assume we longjmp out of the translation loop the same
was as we do out of the execution loop ?

Note: I've started cleaning that on ppc (but not fixing the -2 bug yet)
in there: very much a work in progress but I'd be happy to have initial
feedback (ignore patch 1 about MOL OSI, it's unrelated):

https://github.com/ozbenh/qemu/commits/wip

Cheers,
Ben.