From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753629AbaHNRyZ (ORCPT ); Thu, 14 Aug 2014 13:54:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52726 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751110AbaHNRyY (ORCPT ); Thu, 14 Aug 2014 13:54:24 -0400 Date: Thu, 14 Aug 2014 19:53:46 +0200 From: Frantisek Hrbata To: "H. Peter Anvin" Cc: Dave Hansen , linux-kernel@vger.kernel.org, linux-mm@kvack.org, tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, oleg@redhat.com, kamaleshb@in.ibm.com, hechjie@cn.ibm.com, akpm@linux-foundation.org, dvlasenk@redhat.com, prarit@redhat.com, lwoodman@redhat.com, hannsj_uhl@de.ibm.com Subject: Re: [PATCH 1/1] x86: add phys addr validity check for /dev/mem mmap Message-ID: <20140814175346.GB7575@localhost.localdomain> Reply-To: Frantisek Hrbata References: <1408025927-16826-1-git-send-email-fhrbata@redhat.com> <1408025927-16826-2-git-send-email-fhrbata@redhat.com> <53ECE573.1030405@intel.com> <53ECEFF5.1040800@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53ECEFF5.1040800@zytor.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 14, 2014 at 10:20:53AM -0700, H. Peter Anvin wrote: > On 08/14/2014 09:36 AM, Dave Hansen wrote: > > Thanks for dredging this back up! > > > > On 08/14/2014 07:18 AM, Frantisek Hrbata wrote: > >> +int valid_phys_addr_range(phys_addr_t addr, size_t count) > >> +{ > >> + return addr + count <= __pa(high_memory); > >> +} > > > > Is this correct on 32-bit? It would limit /dev/mem to memory below 896MB. > > > > Last I checked, /dev/mem was already broken for highmem... which is > actually a problem. I would prefer to see it fixed. > > -hpa > Hi Peter, thank you for jumping in again. I'm not going to pretent I fully understand this code, as proven by Dave :), but wouldn't it help just to move the high_memory check directly to the xlate_dev_mem_ptr. Meaning no high_memory check in valid_phys_addr_range for x86. I sent more info in my reply to Dave's mail. Again many thanks. -- Frantisek Hrbata