From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (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 3xK1T138p7zDrVj for ; Sat, 29 Jul 2017 07:00:21 +1000 (AEST) Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v6SKxKdO143506 for ; Fri, 28 Jul 2017 17:00:19 -0400 Received: from e24smtp02.br.ibm.com (e24smtp02.br.ibm.com [32.104.18.86]) by mx0a-001b2d01.pphosted.com with ESMTP id 2c0bnu2se0-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 28 Jul 2017 17:00:19 -0400 Received: from localhost by e24smtp02.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 28 Jul 2017 18:00:16 -0300 Received: from d24av04.br.ibm.com (d24av04.br.ibm.com [9.8.31.97]) by d24relay03.br.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v6SL0EIs39649298 for ; Fri, 28 Jul 2017 18:00:14 -0300 Received: from d24av04.br.ibm.com (localhost [127.0.0.1]) by d24av04.br.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v6SL0Ejd013096 for ; Fri, 28 Jul 2017 18:00:14 -0300 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 Message-Id: <87tw1we0q5.fsf@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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