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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 6A3ACC10F00 for ; Thu, 28 Feb 2019 09:55:57 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B22102171F for ; Thu, 28 Feb 2019 09:55:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B22102171F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.vnet.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4497Gf4yn8zDqMf for ; Thu, 28 Feb 2019 20:55:54 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.158.5; helo=mx0a-001b2d01.pphosted.com; envelope-from=ego@linux.vnet.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com Received: from mx0a-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 4497Dq3FFxzDqHg for ; Thu, 28 Feb 2019 20:54:19 +1100 (AEDT) Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x1S9nb4r076770 for ; Thu, 28 Feb 2019 04:54:16 -0500 Received: from e13.ny.us.ibm.com (e13.ny.us.ibm.com [129.33.205.203]) by mx0a-001b2d01.pphosted.com with ESMTP id 2qxbk3d9g9-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 28 Feb 2019 04:54:16 -0500 Received: from localhost by e13.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 28 Feb 2019 09:54:13 -0000 Received: from b01ledav004.gho.pok.ibm.com (b01ledav004.gho.pok.ibm.com [9.57.199.109]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x1S9sCWX16974074 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 28 Feb 2019 09:54:12 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3A4EC11206B; Thu, 28 Feb 2019 09:54:12 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EC365112064; Thu, 28 Feb 2019 09:54:11 +0000 (GMT) Received: from sofia.ibm.com (unknown [9.124.35.84]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Thu, 28 Feb 2019 09:54:11 +0000 (GMT) Received: by sofia.ibm.com (Postfix, from userid 1000) id 728C12E2D5F; Thu, 28 Feb 2019 15:24:10 +0530 (IST) Date: Thu, 28 Feb 2019 15:24:10 +0530 From: Gautham R Shenoy To: Russell Currey Subject: Re: [PATCH v2] powerpc/powernv/idle: Restore IAMR after idle References: <20190208111103.4901-1-ruscur@russell.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190208111103.4901-1-ruscur@russell.cc> User-Agent: Mutt/1.5.23 (2014-03-12) X-TM-AS-GCONF: 00 x-cbid: 19022809-0064-0000-0000-000003B0C11C X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010679; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000281; SDB=6.01167519; UDB=6.00609945; IPR=6.00948133; MB=3.00025777; MTD=3.00000008; XFM=3.00000015; UTC=2019-02-28 09:54:14 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19022809-0065-0000-0000-00003C8FCF5A Message-Id: <20190228095410.GC24751@in.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-02-28_05:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=933 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902280070 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: , Reply-To: ego@linux.vnet.ibm.com Cc: linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hello Russell, On Fri, Feb 08, 2019 at 10:11:03PM +1100, Russell Currey wrote: > Without restoring the IAMR after idle, execution prevention on POWER9 > with Radix MMU is overwritten and the kernel can freely execute userspace without > faulting. > > This is necessary when returning from any stop state that modifies user > state, as well as hypervisor state. > > To test how this fails without this patch, load the lkdtm driver and > do the following: > > echo EXEC_USERSPACE > /sys/kernel/debug/provoke-crash/DIRECT > > which won't fault, then boot the kernel with powersave=off, where it > will fault. Applying this patch will fix this. > > Fixes: 3b10d0095a1e ("powerpc/mm/radix: Prevent kernel execution of user > space") > Cc: > Signed-off-by: Russell Currey > --- > Since v1: > - no longer use paca to save IAMR, instead use _DAR (thanks mpe) Looks good to me. Once we move to Nick Piggin's C-based save/restore code, we will be saving all these SPR values on the stack anyway. Reviewed-by: Gautham R. Shenoy -- Thanks and Regards gautham.