Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754734AbYGEP1h (ORCPT ); Sat, 5 Jul 2008 11:27:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751532AbYGEP1a (ORCPT ); Sat, 5 Jul 2008 11:27:30 -0400 Received: from ihemail2.lucent.com ([135.245.0.35]:39805 "EHLO ihemail2.lucent.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751415AbYGEP13 (ORCPT ); Sat, 5 Jul 2008 11:27:29 -0400 Message-ID: <00ae01c8deb3$913522b0$01fca8c0@microsof60b8d6> From: "Gavin Shan" To: "Arjan van de Ven" Cc: References: <008101c8deaa$52cf19d0$01fca8c0@microsof60b8d6> <20080705081737.5bc17450@infradead.org> Subject: Re: Tough Issue: kernel instruction corruption Date: Sat, 5 Jul 2008 23:26:57 +0800 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by alpha.home.local id m65FRffq028997 Content-Length: 1688 Lines: 36 >> Hello, I'm faced a tough issue recently: instructions of kernel >> were corrupted. There has 2 PCI buses on my board and lots >> of PCI devices with DMA capabality involved. I'm suspecting >> the kernel instructions were corrupted by DMA operations driving >> by those PCI devices with DMA capabality. >> >> Anybody have tried to protect kernel instructions from this case >> or have any ideas to protect kernel text section? > > if you have a modern Intel board, you can enable the IOMMU on it that > will protect the kernel text (well, all of memory) from rogue DMA. > PPC generally has similar capabilities, as do some IBM x86 chipsets. PPC is used now and PPC doesn't have 2 kinds of MMUs. I don't know much about IOMMU. Is it part of CPU? > > Without an IOMMU it's basically impossible to protect against such DMA. I did a google with "instruction"+"corruption"+"DMA" and found one matched patent. And I go through the datasheet of PCI chips on my board, unfortunately, the PCI chip didn't supply address protection from vager DMA. http://www.freepatentsonline.com/y2005/0182862.html > > -- > If you want to reach me at my work email, use arjan@linux.intel.com > For development, discussion and tips for power savings, > visit http://www.lesswatts.org > -- > 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/ >????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m???? ????????I?