From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C54CC11D00 for ; Thu, 20 Feb 2020 21:53:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 77B61206DB for ; Thu, 20 Feb 2020 21:53:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729189AbgBTVx3 (ORCPT ); Thu, 20 Feb 2020 16:53:29 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:60434 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726670AbgBTVx2 (ORCPT ); Thu, 20 Feb 2020 16:53:28 -0500 Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 01KLpWAZ102715; Thu, 20 Feb 2020 16:53:12 -0500 Received: from ppma01dal.us.ibm.com (83.d6.3fa9.ip4.static.sl-reverse.com [169.63.214.131]) by mx0a-001b2d01.pphosted.com with ESMTP id 2y8ubgsx6m-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 20 Feb 2020 16:53:11 -0500 Received: from pps.filterd (ppma01dal.us.ibm.com [127.0.0.1]) by ppma01dal.us.ibm.com (8.16.0.27/8.16.0.27) with SMTP id 01KLq7Ma016004; Thu, 20 Feb 2020 21:53:11 GMT Received: from b03cxnp08027.gho.boulder.ibm.com (b03cxnp08027.gho.boulder.ibm.com [9.17.130.19]) by ppma01dal.us.ibm.com with ESMTP id 2y6897c33u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 20 Feb 2020 21:53:10 +0000 Received: from b03ledav004.gho.boulder.ibm.com (b03ledav004.gho.boulder.ibm.com [9.17.130.235]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 01KLr9WH41812454 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 20 Feb 2020 21:53:09 GMT Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 86AF878069; Thu, 20 Feb 2020 21:53:09 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 369167805C; Thu, 20 Feb 2020 21:53:08 +0000 (GMT) Received: from leobras.br.ibm.com (unknown [9.18.235.190]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 20 Feb 2020 21:53:07 +0000 (GMT) Message-ID: Subject: Re: [PATCH] powerpc/8xx: Fix clearing of bits 20-23 in ITLB miss From: Leonardo Bras To: christophe.leroy@c-s.fr, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Date: Thu, 20 Feb 2020 18:53:04 -0300 In-Reply-To: <1cd9c970771ba9f08621ae8357340c93f386bc24.camel@linux.ibm.com> References: <1cd9c970771ba9f08621ae8357340c93f386bc24.camel@linux.ibm.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-7O7yPN7c8Y5tej+lpYHC" User-Agent: Evolution 3.34.3 (3.34.3-1.fc31) MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-02-20_17:2020-02-19,2020-02-20 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 priorityscore=1501 suspectscore=0 mlxscore=0 mlxlogscore=999 bulkscore=0 malwarescore=0 spamscore=0 impostorscore=0 phishscore=0 adultscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002200160 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-7O7yPN7c8Y5tej+lpYHC Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2020-02-11 at 01:28 -0300, Leonardo Bras wrote: > Looks a valid change. > rlwimi r10, r10, 0, 0x0f00 means:=20 > r10 =3D ((r10 << 0) & 0x0f00) | (r10 & ~0x0f00) which ends up being > r10 =3D r10=20 >=20 > On ISA, rlwinm is recommended for clearing high order bits. > rlwinm r10, r10, 0, ~0x0f00 means: > r10 =3D (r10 << 0) & ~0x0f00 >=20 > Which does exactly what the comments suggests. >=20 > FWIW: > Reviwed-by: Leonardo Bras Sorry, I just realized the above was not very clear on my part. What I meant to say was: I think your change is correct, as it correctly fixes this line. I would suggest adding the text bellow to your commit message, making it easier to understand why rlwimi is not the right instruction clear bytes 20-23, and why rlwinm is. The current instruction can be translated to C as: rlwimi r10, r10, 0, 0x0f00 r10 =3D ((r10 << 0) & 0x0f00) | (r10 & ~0x0f00) -> r10 =3D (r10 & 0x0f00) | (r10 & ~0x0f00) -> r10 =3D r10 The new proposed instruction can be translated to C as: rlwinm r10, r10, 0, ~0x0f00 -> r10 =3D (r10 << 0) & ~0x0f00 Which clears bits 20-23 as comment on code states. Best regards, Leonardo Bras --=-7O7yPN7c8Y5tej+lpYHC Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEMdeUgIzgjf6YmUyOlQYWtz9SttQFAl5O/8AACgkQlQYWtz9S ttQehQ//ejnIk/wjlRFuOR4Xe55pqcLVaHnyyveqvLIM6MA9GE7AQ3woMVFJSvXW qoGDE/Daf26yPaFGEB8vsljZhkE1qtt6bnV3JtXVxYLdvv2EkSPPgZ2ZfDuBuv7Q VWVpWOQ7rv9TPry/pfx5DZOaZFbUgB8I7n90ZfRl5hUBKI94FQ5Yf6yujkyfuPrP 1oPmXqSBZ9NIaHk7cATp3McpFtBOwd1wWvB2xGHycBuK+zIbj8xFaP3zc8EU9yUq Uw/rtoJuRBUTVOIyrIypYIe3g5Kgf8pGSMMDrRUmWH/K6o5//o5eP8STJtC8Lzdl oVQ6VXvGmLNIMbLASut2J9VDV2QT8okWoXl9lf6WOq47hm3dvraMjOLihHT3DRGg WtDbTliELv7FtXC3+WvwzsjuNaAb3GhKT4FnQ5UWp7z8BJGXV8zRFKpj9W8SY1iG W+ndgjCdHq//CV0M1W2H3fDvZqPzoUVmBAaQlUHCBrb2eJ5IXx3SFc73mIEgDi0h FoqwEIYNF9jAKuIR0AvnpmUf7cz1/isDn2zg/6ttjjUESx0vSS0nQDQK5futrZbD PO7/UBx4mq5MTppxksWYam2Q7eQ9b9Xd6F1o3kuiossMz10cn2FvCapxQM9gQhrb doVD95YNX2L5d1l3ABul3bWfoOT32EqECUf9iPGpbgHDy3GQIt4= =qHE2 -----END PGP SIGNATURE----- --=-7O7yPN7c8Y5tej+lpYHC--