From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751937AbbLHSmn (ORCPT ); Tue, 8 Dec 2015 13:42:43 -0500 Received: from www.linutronix.de ([62.245.132.108]:51787 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751219AbbLHSmm (ORCPT ); Tue, 8 Dec 2015 13:42:42 -0500 Date: Tue, 8 Dec 2015 19:41:53 +0100 (CET) From: Thomas Gleixner To: Dave Hansen cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, dave.hansen@linux.intel.com Subject: Re: [PATCH 27/34] x86, pkeys: make mprotect_key() mask off additional vm_flags In-Reply-To: <20151204011502.251A0E5B@viggo.jf.intel.com> Message-ID: References: <20151204011424.8A36E365@viggo.jf.intel.com> <20151204011502.251A0E5B@viggo.jf.intel.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001,URIBL_BLOCKED=0.001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 3 Dec 2015, Dave Hansen wrote: > > From: Dave Hansen > > Today, mprotect() takes 4 bits of data: PROT_READ/WRITE/EXEC/NONE. > Three of those bits: READ/WRITE/EXEC get translated directly in to > vma->vm_flags by calc_vm_prot_bits(). If a bit is unset in > mprotect()'s 'prot' argument then it must be cleared in vma->vm_flags > during the mprotect() call. > > We do the by first calculating the VMA flags we want set, then > clearing the ones we do not want to inherit from the original VMA: > > vm_flags = calc_vm_prot_bits(prot, key); > ... > newflags = vm_flags; > newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); > > However, we *also* want to mask off the original VMA's vm_flags in > which we store the protection key. > > To do that, this patch adds a new macro: > > ARCH_VM_FLAGS_AFFECTED_BY_MPROTECT -ENOSUCHMACRO > which allows the architecture to specify additional bits that it would > like cleared. We use that to ensure that the VM_PKEY_BIT* bits get > cleared. Other than that: Reviewed-by: Thomas Gleixner From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f41.google.com (mail-wm0-f41.google.com [74.125.82.41]) by kanga.kvack.org (Postfix) with ESMTP id A20186B0253 for ; Tue, 8 Dec 2015 13:42:44 -0500 (EST) Received: by wmww144 with SMTP id w144so192487742wmw.1 for ; Tue, 08 Dec 2015 10:42:44 -0800 (PST) Received: from Galois.linutronix.de (linutronix.de. [2001:470:1f0b:db:abcd:42:0:1]) by mx.google.com with ESMTPS id qr6si5918243wjc.206.2015.12.08.10.42.43 for (version=TLS1_2 cipher=AES128-SHA bits=128/128); Tue, 08 Dec 2015 10:42:43 -0800 (PST) Date: Tue, 8 Dec 2015 19:41:53 +0100 (CET) From: Thomas Gleixner Subject: Re: [PATCH 27/34] x86, pkeys: make mprotect_key() mask off additional vm_flags In-Reply-To: <20151204011502.251A0E5B@viggo.jf.intel.com> Message-ID: References: <20151204011424.8A36E365@viggo.jf.intel.com> <20151204011502.251A0E5B@viggo.jf.intel.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, dave.hansen@linux.intel.com On Thu, 3 Dec 2015, Dave Hansen wrote: > > From: Dave Hansen > > Today, mprotect() takes 4 bits of data: PROT_READ/WRITE/EXEC/NONE. > Three of those bits: READ/WRITE/EXEC get translated directly in to > vma->vm_flags by calc_vm_prot_bits(). If a bit is unset in > mprotect()'s 'prot' argument then it must be cleared in vma->vm_flags > during the mprotect() call. > > We do the by first calculating the VMA flags we want set, then > clearing the ones we do not want to inherit from the original VMA: > > vm_flags = calc_vm_prot_bits(prot, key); > ... > newflags = vm_flags; > newflags |= (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); > > However, we *also* want to mask off the original VMA's vm_flags in > which we store the protection key. > > To do that, this patch adds a new macro: > > ARCH_VM_FLAGS_AFFECTED_BY_MPROTECT -ENOSUCHMACRO > which allows the architecture to specify additional bits that it would > like cleared. We use that to ensure that the VM_PKEY_BIT* bits get > cleared. Other than that: Reviewed-by: Thomas Gleixner -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org