From patchwork Mon Dec 10 13:58:03 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 153268 Delivered-To: patches@linaro.org Received: by 2002:a2e:299d:0:0:0:0:0 with SMTP id p29-v6csp3589702ljp; Mon, 10 Dec 2018 05:58:06 -0800 (PST) X-Google-Smtp-Source: AFSGD/W83nh2yvoX5sACHcL7n4ZCbFc2UYtYeP5o3I0fEKxhQxSgNXFlfkfQ8BUO5TNVGcIxoYE7 X-Received: by 2002:adf:d243:: with SMTP id o3mr10301041wri.66.1544450286328; Mon, 10 Dec 2018 05:58:06 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1544450286; cv=none; d=google.com; s=arc-20160816; b=Pd1MciCvfjKWekJ6FKXFYUnqB8W+S1645/VjqAYveqYhR2YmgjX4rtx79r0ShPgDWk 8dTNfLZT+HskqFIkWuj7oQkPZArHCkf/oV9g41InKPbTxceCztQpzJZQz0fGKEOga4Vm GqM4VgFm49hgV69cQfA6s/kRo+YvWTxJUkTYlzQpHdNUNuy/sGJy8RxwdUtqtudf9+Nc bi3X7IZ+EoLtDA8kGU0sWQKuEqyZrPCsE3mNMR7ouz8lbvvSl+/nsceA3af/hFRYTXR2 yvLI6PtCccTA57cg0EvJGB/6HVgEpg2x6RDR6gKjvDJsAYwpzTAectfe9W2/lca1hHyJ DsgQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from; bh=yCO7ucJlI/baXDmWPpBnfh43b2IvVKD1hj/FB+sguoY=; b=KumFNPrOMNrtJVets1mjWdPUVoAQthRk7qdnUChv5SEb1DQCJXI5/cKtcrm1mX8nAK Pww+srFhfNxJI05cs8/Ift/eDzwvUYciOlUDwpBS1kSg9CEP+pYmdRM3nRHmz/C4qm7o kG+ju6J94v39qeux18LdkRKvVVFHR78anXFRWYkteX0mpY5+5jH+qiLZy0bWgfxyODig h7v1TGm7rpyZwuLTfFhq4FIy7Das7xZ+wb/ixNbpRfOCPCt5PQt4kJCKV//LiiPyC8Mb 6I49GZ379fHlpXZPoqU0xNwlKRnxpl/p9pdp6w3R+Xhy7fjvZ93zuiULd0eRTTjL5K9K wTzQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of pm215@archaic.org.uk designates 2001:8b0:1d0::2 as permitted sender) smtp.mailfrom=pm215@archaic.org.uk; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org Return-Path: Received: from orth.archaic.org.uk (orth.archaic.org.uk. [2001:8b0:1d0::2]) by mx.google.com with ESMTPS id y203si8273689wmg.193.2018.12.10.05.58.06 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 10 Dec 2018 05:58:06 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of pm215@archaic.org.uk designates 2001:8b0:1d0::2 as permitted sender) client-ip=2001:8b0:1d0::2; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of pm215@archaic.org.uk designates 2001:8b0:1d0::2 as permitted sender) smtp.mailfrom=pm215@archaic.org.uk; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=linaro.org 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 Cc: patches@linaro.org, qemu-s390x@nongnu.org, Cornelia Huck , Christian Borntraeger , Richard Henderson , David Hildenbrand , "Dr . David Alan Gilbert" Subject: [PATCH] hw/s390/ccw.c: Don't take address of packed members 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 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 --- 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(-) -- 2.19.2 Reviewed-by: Farhan Ali 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; - copy_pmcw_to_guest(&dest->pmcw, &src->pmcw); - copy_scsw_to_guest(&dest->scsw, &src->scsw); + srcpmcw = src->pmcw; + copy_pmcw_to_guest(&destpmcw, &srcpmcw); + dest->pmcw = destpmcw; + srcscsw = src->scsw; + copy_scsw_to_guest(&destscsw, &srcscsw); + dest->scsw = destscsw; dest->mba = cpu_to_be64(src->mba); for (i = 0; i < ARRAY_SIZE(dest->mda); i++) { dest->mda[i] = src->mda[i]; @@ -1339,9 +1345,15 @@ static void copy_scsw_from_guest(SCSW *dest, const SCSW *src) static void copy_schib_from_guest(SCHIB *dest, const SCHIB *src) { int i; + PMCW srcpmcw, destpmcw; + SCSW srcscsw, destscsw; - copy_pmcw_from_guest(&dest->pmcw, &src->pmcw); - copy_scsw_from_guest(&dest->scsw, &src->scsw); + srcpmcw = src->pmcw; + copy_pmcw_from_guest(&destpmcw, &srcpmcw); + dest->pmcw = destpmcw; + srcscsw = src->scsw; + copy_scsw_from_guest(&destscsw, &srcscsw); + dest->scsw = destscsw; dest->mba = be64_to_cpu(src->mba); for (i = 0; i < ARRAY_SIZE(dest->mda); i++) { dest->mda[i] = src->mda[i];