From nobody Fri May 3 13:43:28 2024 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=linaro.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1544450349172958.2913238834883; Mon, 10 Dec 2018 05:59:09 -0800 (PST) Received: from localhost ([::1]:32955 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gWM5S-000123-GI for importer@patchew.org; Mon, 10 Dec 2018 08:59:06 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45961) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gWM4Y-0000dj-F5 for qemu-devel@nongnu.org; Mon, 10 Dec 2018 08:58:11 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gWM4X-0002fT-1q for qemu-devel@nongnu.org; Mon, 10 Dec 2018 08:58:10 -0500 Received: from orth.archaic.org.uk ([2001:8b0:1d0::2]:53408) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gWM4W-0002cz-QU; Mon, 10 Dec 2018 08:58:08 -0500 Received: from pm215 by orth.archaic.org.uk with local (Exim 4.89) (envelope-from ) id 1gWM4S-0008Vd-9A; Mon, 10 Dec 2018 13:58:04 +0000 From: Peter Maydell To: qemu-devel@nongnu.org Date: Mon, 10 Dec 2018 13:58:03 +0000 Message-Id: <20181210135803.20208-1-peter.maydell@linaro.org> X-Mailer: git-send-email 2.19.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2001:8b0:1d0::2 Subject: [Qemu-devel] [PATCH] hw/s390/ccw.c: Don't take address of packed members X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Hildenbrand , Cornelia Huck , "Dr . David Alan Gilbert" , Christian Borntraeger , qemu-s390x@nongnu.org, patches@linaro.org, Richard Henderson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" Taking the address of a field in a packed struct is a bad idea, because it might not be actually aligned enough for that pointer type (and thus cause a crash on dereference on some host architectures). Newer versions of clang warn about this. Avoid the problem by using local copies of the PMCW and SCSW struct fields in copy_schib_from_guest() and copy_schib_to_guest(). Signed-off-by: Peter Maydell Reviewed-by: Farhan Ali --- This seemed like a not totally ugly and reasonably localised fix that satisfies clang. Oddly, this makes the generated object file 15K smaller (421K vs 406K), so it might even be better code... hw/s390x/css.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/hw/s390x/css.c b/hw/s390x/css.c index 04ec5cc9705..ef07691e36b 100644 --- a/hw/s390x/css.c +++ b/hw/s390x/css.c @@ -1290,9 +1290,15 @@ void copy_scsw_to_guest(SCSW *dest, const SCSW *src) static void copy_schib_to_guest(SCHIB *dest, const SCHIB *src) { int i; + PMCW srcpmcw, destpmcw; + SCSW srcscsw, destscsw; =20 - copy_pmcw_to_guest(&dest->pmcw, &src->pmcw); - copy_scsw_to_guest(&dest->scsw, &src->scsw); + srcpmcw =3D src->pmcw; + copy_pmcw_to_guest(&destpmcw, &srcpmcw); + dest->pmcw =3D destpmcw; + srcscsw =3D src->scsw; + copy_scsw_to_guest(&destscsw, &srcscsw); + dest->scsw =3D destscsw; dest->mba =3D cpu_to_be64(src->mba); for (i =3D 0; i < ARRAY_SIZE(dest->mda); i++) { dest->mda[i] =3D src->mda[i]; @@ -1339,9 +1345,15 @@ static void copy_scsw_from_guest(SCSW *dest, const S= CSW *src) static void copy_schib_from_guest(SCHIB *dest, const SCHIB *src) { int i; + PMCW srcpmcw, destpmcw; + SCSW srcscsw, destscsw; =20 - copy_pmcw_from_guest(&dest->pmcw, &src->pmcw); - copy_scsw_from_guest(&dest->scsw, &src->scsw); + srcpmcw =3D src->pmcw; + copy_pmcw_from_guest(&destpmcw, &srcpmcw); + dest->pmcw =3D destpmcw; + srcscsw =3D src->scsw; + copy_scsw_from_guest(&destscsw, &srcscsw); + dest->scsw =3D destscsw; dest->mba =3D be64_to_cpu(src->mba); for (i =3D 0; i < ARRAY_SIZE(dest->mda); i++) { dest->mda[i] =3D src->mda[i]; --=20 2.19.2