Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753046AbdG1VAX (ORCPT ); Fri, 28 Jul 2017 17:00:23 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:41380 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752841AbdG1VAU (ORCPT ); Fri, 28 Jul 2017 17:00:20 -0400 References: <1500177424-13695-1-git-send-email-linuxram@us.ibm.com> <1500177424-13695-28-git-send-email-linuxram@us.ibm.com> From: Thiago Jung Bauermann To: Ram Pai Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, arnd@arndb.de, corbet@lwn.net, mhocko@kernel.org, dave.hansen@intel.com, mingo@redhat.com, paulus@samba.org, aneesh.kumar@linux.vnet.ibm.com, akpm@linux-foundation.org, khandual@linux.vnet.ibm.com Subject: Re: [RFC v6 27/62] powerpc: helper to validate key-access permissions of a pte In-reply-to: <1500177424-13695-28-git-send-email-linuxram@us.ibm.com> Date: Fri, 28 Jul 2017 18:00:02 -0300 MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-MML: disable x-cbid: 17072821-0028-0000-0000-000001CCB3EE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17072821-0029-0000-0000-000014CF1B41 Message-Id: <87tw1we0q5.fsf@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-07-28_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1706020000 definitions=main-1707280337 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1044 Lines: 41 Ram Pai writes: > --- a/arch/powerpc/mm/pkeys.c > +++ b/arch/powerpc/mm/pkeys.c > @@ -201,3 +201,36 @@ int __arch_override_mprotect_pkey(struct vm_area_struct *vma, int prot, > */ > return vma_pkey(vma); > } > + > +static bool pkey_access_permitted(int pkey, bool write, bool execute) > +{ > + int pkey_shift; > + u64 amr; > + > + if (!pkey) > + return true; > + > + pkey_shift = pkeyshift(pkey); > + if (!(read_uamor() & (0x3UL << pkey_shift))) > + return true; > + > + if (execute && !(read_iamr() & (IAMR_EX_BIT << pkey_shift))) > + return true; > + > + if (!write) { > + amr = read_amr(); > + if (!(amr & (AMR_RD_BIT << pkey_shift))) > + return true; > + } > + > + amr = read_amr(); /* delay reading amr uptil absolutely needed */ Actually, this is causing amr to be read twice in case control enters the "if (!write)" block above but doesn't enter the other if block nested in it. read_amr should be called only once, right before "if (!write)". -- Thiago Jung Bauermann IBM Linux Technology Center