Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757048AbYCATyv (ORCPT ); Sat, 1 Mar 2008 14:54:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756744AbYCATym (ORCPT ); Sat, 1 Mar 2008 14:54:42 -0500 Received: from terminus.zytor.com ([198.137.202.10]:55533 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756491AbYCATyl (ORCPT ); Sat, 1 Mar 2008 14:54:41 -0500 Message-ID: <47C9B443.9000905@zytor.com> Date: Sat, 01 Mar 2008 11:53:39 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: "Klaus S. Madsen" CC: Ingo Molnar , LKML , Pavel Machek , "Rafael J. Wysocki" , Thomas Gleixner Subject: Re: Regression in 2.6.25-rc3: s2ram segfaults before suspending References: <20080228094000.GA2987@elte.hu> <20080228150444.GG17932@hjernemadsen.org> <47C6F4F9.90700@zytor.com> <20080228192404.GH17932@hjernemadsen.org> <47C70C01.4020605@zytor.com> <20080228194920.GJ17932@hjernemadsen.org> <47C739A6.5020608@zytor.com> <20080229070028.GK17932@hjernemadsen.org> <47C873AA.6040305@zytor.com> <20080229212654.GL27212@elte.hu> <20080301094525.GQ17932@hjernemadsen.org> In-Reply-To: <20080301094525.GQ17932@hjernemadsen.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2256 Lines: 48 Klaus S. Madsen wrote: > On Fri, Feb 29, 2008 at 22:26:54 +0100, Ingo Molnar wrote: >> * H. Peter Anvin wrote: >> >>> Klaus S. Madsen wrote: >>>> open("/dev/mem", O_RDWR) = 5 >>>> mmap2(NULL, 1282, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_SHARED|MAP_FIXED, 5, 0) = 0 >>>> mmap2(0xa0000, 393216, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, 5, 0xa0) = 0xa0000 >>> ^^^^^^^^^^^^^^^^^^^^ >>>> close(5) = 0 >>>> ioperm(0, 0x400, 0x1) = 0 >>>> iopl(0x3) = 0 >>>> access("/sys/bus/pci", R_OK) = 0 >>>> write(1, "Calling get_mode\n", 17) = 17 >>>> vm86(0x1, 0xb7f14ccc, 0xb7f14830, 0xc000, 0x18b6 >>>> --- SIGSEGV (Segmentation fault) @ 0 (0) --- >>>> +++ killed by SIGSEGV (core dumped) +++ >>> This is the VGA BIOS being mapped, it's mapped PROT_READ|PROT_WRITE, but >>> no PROT_EXEC; if the kernel is NX-capable it *should* segfault trying to >>> execute out of this area, which is exactly what will happen when vm86 >>> executes INT 10h. >>> >>> If we can find that mmap() in the s2ram source code and add PROT_EXEC >>> to it, it would be interesting. >> Klaus, could you send your .config as well? Lets make sure that NX is >> even relevant in this context. > Allright. The mmap in question is in the x86-common.c file in libx86, > and adding PROT_EXEC to it solves the problem. > > I have attached my .config. > > The only thing I don't understand is why this is suddenly a problem with > 2.6.25, and not with 2.6.24? Is there a bug in 2.6.24 and previously > that allows real-mode execution of non-executable pages? > One wonders, especially since the checkin it was bisected to it had nothing to do with NX. I suspect there is either a bug in the NX logic, which this checkin inadvertently fixed(!), or there is an ad hoc hack that should probably never have existed. More investigation necessary, but now we know a lot more. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/