From nobody Sat Feb 7 06:40:08 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1568642738; cv=none; d=zoho.com; s=zohoarc; b=M5OKA05IUmUHcldP/BvMJPyLIsIvYDH7AaK6UUiUdd+G8sWYBi/orsTKZ52fcseIKp/EH4W+oki/fbmHzSt4PpeIzxz5QPhsmFUcZHm4lwmwtfNAk3wy8JxYI391a895o5ztPJ7h81Ifgwr5LtV4OuKHiNU7f1A2tkj14ySfol0= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zoho.com; s=zohoarc; t=1568642738; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To:ARC-Authentication-Results; bh=Av0Dq9BYaqcD+LLNtTXDkCb04cn2AKYdyJxoE+r7pYs=; b=ea/+m8R07N8tikgEdq6Z+XM3FEBCIJxhQa8WIlHR8A2wljLEe/M9/C7ehbMyP2uzU2sEhORpQO1UTDTMH7C/KHh530CnDEYpksAvhI1L33NAzySHc298V46PSq/DtWZzpEvdNn5bI1YtNqd9LKiv3xApCuX1vGkobInmTkNeAB4= ARC-Authentication-Results: i=1; mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1568642738649790.7366942640198; Mon, 16 Sep 2019 07:05:38 -0700 (PDT) Received: from localhost ([::1]:34564 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i9rdJ-00006O-6T for importer@patchew.org; Mon, 16 Sep 2019 10:05:37 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45888) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i9rWf-0002qG-UD for qemu-devel@nongnu.org; Mon, 16 Sep 2019 09:58:47 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i9rWd-0000CO-LN for qemu-devel@nongnu.org; Mon, 16 Sep 2019 09:58:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35808) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i9rWd-0000C9-8M; Mon, 16 Sep 2019 09:58:43 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8509A2F30C1; Mon, 16 Sep 2019 13:58:42 +0000 (UTC) Received: from t460s.redhat.com (ovpn-117-103.ams2.redhat.com [10.36.117.103]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6625810013A1; Mon, 16 Sep 2019 13:58:40 +0000 (UTC) From: David Hildenbrand To: qemu-devel@nongnu.org Date: Mon, 16 Sep 2019 15:57:42 +0200 Message-Id: <20190916135806.1269-6-david@redhat.com> In-Reply-To: <20190916135806.1269-1-david@redhat.com> References: <20190916135806.1269-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Mon, 16 Sep 2019 13:58:42 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v3 05/29] s390x/tcg: MVC: Increment the length once X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Florian Weimer , Thomas Huth , David Hildenbrand , =?UTF-8?q?Dan=20Hor=C3=A1k?= , Cornelia Huck , Richard Henderson , Stefano Brivio , qemu-s390x@nongnu.org, Cole Robinson , Richard Henderson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" Let's increment the length once. While at it, cleanup the comment. The memset() example is given as a programming note in the PoP, so drop the description. Reviewed-by: Richard Henderson Signed-off-by: David Hildenbrand --- target/s390x/mem_helper.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c index 58ab2e48e3..013e8d6045 100644 --- a/target/s390x/mem_helper.c +++ b/target/s390x/mem_helper.c @@ -320,16 +320,20 @@ static uint32_t do_helper_mvc(CPUS390XState *env, uin= t32_t l, uint64_t dest, HELPER_LOG("%s l %d dest %" PRIx64 " src %" PRIx64 "\n", __func__, l, dest, src); =20 - /* mvc and memmove do not behave the same when areas overlap! */ - /* mvc with source pointing to the byte after the destination is the - same as memset with the first source byte */ + /* MVC always copies one more byte than specified - maximum is 256 */ + l++; + + /* + * "When the operands overlap, the result is obtained as if the operan= ds + * were processed one byte at a time". Only non-destructive overlaps + * behave like memmove(). + */ if (dest =3D=3D src + 1) { - fast_memset(env, dest, cpu_ldub_data_ra(env, src, ra), l + 1, ra); - } else if (dest < src || src + l < dest) { - fast_memmove(env, dest, src, l + 1, ra); + fast_memset(env, dest, cpu_ldub_data_ra(env, src, ra), l, ra); + } else if (dest < src || src + l <=3D dest) { + fast_memmove(env, dest, src, l, ra); } else { - /* slow version with byte accesses which always work */ - for (i =3D 0; i <=3D l; i++) { + for (i =3D 0; i < l; i++) { uint8_t x =3D cpu_ldub_data_ra(env, src + i, ra); cpu_stb_data_ra(env, dest + i, x, ra); } --=20 2.21.0