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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 54BEDC433F5 for ; Wed, 30 Mar 2022 18:41:42 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4KTFdc4Dlxz3c16 for ; Thu, 31 Mar 2022 05:41:40 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=JnndgLnU; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.158.5; helo=mx0b-001b2d01.pphosted.com; envelope-from=naveen.n.rao@linux.vnet.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=JnndgLnU; dkim-atps=neutral Received: from mx0b-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4KTFcq27LDz2yMK for ; Thu, 31 Mar 2022 05:40:58 +1100 (AEDT) Received: from pps.filterd (m0127361.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 22UI0JUA028229; Wed, 30 Mar 2022 18:40:27 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=date : from : subject : to : cc : references : in-reply-to : message-id : content-type : content-transfer-encoding : mime-version; s=pp1; bh=yYaqFrYKOsWX0AAm5jWdnXfpOzmVYQfexOdLzGH70SM=; b=JnndgLnUoVoqFUh3c+uTA+ZqCtaSypIDZk1GaVB+Lc24wq/Ohbt7ojtzG2IdlgfAaVmq b231O5PDrITVeBBsr+t17ja3mqv6vwkQEv4JwVJr6Jdn+9z7Lg9Imc3mWXRXI1esS3qB wKyH3kDP+Qe+tqI/rPtyxOzX+DRA8klUcERXqjQOXeAZyHLteRFjcnZM4Iplna/eqr1E jnypdRlUo0p6hZyVt9TBJPxA+4wkuly8LgxfP5mffi6hYQQfE3PuGlvA5X1bkO/wTcuJ i1QCa9bzpvlHoCpvZ7vPYMny73eykBAjPJ8ZDak7KFW8OQsTaqKdJ86XsIqCV9y95zj+ Lg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3f4v3vgq71-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 30 Mar 2022 18:40:26 +0000 Received: from m0127361.ppops.net (m0127361.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 22UILvrc015655; Wed, 30 Mar 2022 18:40:26 GMT Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 3f4v3vgq6d-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 30 Mar 2022 18:40:26 +0000 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 22UIXYRv024126; Wed, 30 Mar 2022 18:40:24 GMT Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by ppma03ams.nl.ibm.com with ESMTP id 3f1tf9h5c7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 30 Mar 2022 18:40:24 +0000 Received: from b06wcsmtp001.portsmouth.uk.ibm.com (b06wcsmtp001.portsmouth.uk.ibm.com [9.149.105.160]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 22UIeMib21758426 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 30 Mar 2022 18:40:22 GMT Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 17866A405B; Wed, 30 Mar 2022 18:40:22 +0000 (GMT) Received: from b06wcsmtp001.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CD030A4054; Wed, 30 Mar 2022 18:40:21 +0000 (GMT) Received: from localhost (unknown [9.43.30.177]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 30 Mar 2022 18:40:21 +0000 (GMT) Date: Thu, 31 Mar 2022 00:10:20 +0530 From: "Naveen N. Rao" Subject: Re: [RFC PATCH 3/3] objtool/mcount: Add powerpc specific functions To: Christophe Leroy , Josh Poimboeuf , Michael Ellerman References: <20220318105140.43914-1-sv@linux.ibm.com> <20220318105140.43914-4-sv@linux.ibm.com> <0b55f122-4760-c1ba-840a-0911cefec2ad@csgroup.eu> <20220328195920.dqlfra3lcardko6r@treble> <87mth9ezml.fsf@mpe.ellerman.id.au> In-Reply-To: User-Agent: astroid/4d6b06ad (https://github.com/astroidmail/astroid) Message-Id: <1648665137.s2tuu8nsoa.naveen@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed X-TM-AS-GCONF: 00 X-Proofpoint-GUID: FtdX2iafIxDAA4x2CAq9ARVm1EQ0W8bq X-Proofpoint-ORIG-GUID: C0IxmeimH_DRK4fHLec3HEyj_muH7uYI Content-Transfer-Encoding: quoted-printable X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.850,Hydra:6.0.425,FMLib:17.11.64.514 definitions=2022-03-30_06,2022-03-30_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 lowpriorityscore=0 suspectscore=0 clxscore=1015 phishscore=0 mlxlogscore=999 adultscore=0 impostorscore=0 priorityscore=1501 malwarescore=0 mlxscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2202240000 definitions=main-2203300090 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "aik@ozlabs.ru" , "linux-kernel@vger.kernel.org" , "rostedt@goodmis.org" , Peter Zijlstra , Sathvika Vasireddy , "linuxppc-dev@lists.ozlabs.org" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Christophe Leroy wrote: >=20 >=20 > Le 29/03/2022 =C3=A0 14:01, Michael Ellerman a =C3=A9crit=C2=A0: >> Josh Poimboeuf writes: >>> On Sun, Mar 27, 2022 at 09:09:20AM +0000, Christophe Leroy wrote: >>>> What are current works in progress on objtool ? Should I wait Josh's >>>> changes before starting looking at all this ? Should I wait for anythi= ng >>>> else ? >>> >>> I'm not making any major changes to the code, just shuffling things >>> around to make the interface more modular. I hope to have something >>> soon (this week). Peter recently added a big feature (Intel IBT) which >>> is already in -next. >>> >>> Contributions are welcome, with the understanding that you'll help >>> maintain it ;-) >>> >>> Some years ago Kamalesh Babulal had a prototype of objtool for ppc64le >>> which did the full stack validation. I'm not sure what ever became of >>> that. >>=20 >> From memory he was starting to clean the patches up in late 2019, but I >> guess that probably got derailed by COVID. AFAIK he never posted >> anything. Maybe someone at IBM has a copy internally (Naveen?). Kamalesh had a WIP series to enable stack validation on powerpc. From=20 what I recall, he was waiting on and/or working with the arm64 folks=20 around some of the common changes needed in objtool. >>=20 >>> FWIW, there have been some objtool patches for arm64 stack validation, >>> but the arm64 maintainers have been hesitant to get on board with >>> objtool, as it brings a certain maintenance burden. Especially for the >>> full stack validation and ORC unwinder. But if you only want inline >>> static calls and/or mcount then it'd probably be much easier to >>> maintain. >>=20 >> I would like to have the stack validation, but I am also worried about >> the maintenance burden. >>=20 >> I guess we start with mcount, which looks pretty minimal judging by this >> series, and see how we go from there. >>=20 >=20 > I'm not sure mcount is really needed as we have recordmcount, but at=20 > least it is an easy one to start with and as we have recordmount we can=20 > easily compare the results and check it works as expected. On the contrary, I think support for mcount in objtool is something we=20 want to get going soon (hopefully, in time for v5.19) given the issues=20 we are seeing with recordmcount: - https://github.com/linuxppc/issues/issues/388 - https://lore.kernel.org/all/20220211014313.1790140-1-aik@ozlabs.ru/ - Naveen