From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bartlomiej Zolnierkiewicz Subject: Re: [PATCH] siimage: fix kernel oops on PPC 44x Date: Wed, 9 Apr 2008 20:14:01 +0200 Message-ID: <200804092014.01643.bzolnier@gmail.com> References: <200804080005.03683.sshtylyov@ru.mvista.com> <200804072330.00610.bzolnier@gmail.com> <47FB6EA5.4070606@ru.mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from fk-out-0910.google.com ([209.85.128.184]:62222 "EHLO fk-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751744AbYDISiY (ORCPT ); Wed, 9 Apr 2008 14:38:24 -0400 Received: by fk-out-0910.google.com with SMTP id 19so3447519fkr.5 for ; Wed, 09 Apr 2008 11:38:23 -0700 (PDT) In-Reply-To: <47FB6EA5.4070606@ru.mvista.com> Content-Disposition: inline Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Sergei Shtylyov Cc: linux-ide@vger.kernel.org, linuxppc-dev@ozlabs.org On Tuesday 08 April 2008, Sergei Shtylyov wrote: > Bartlomiej Zolnierkiewicz wrote: > > >>Fix kernel oops due to machine check occuring in init_chipset_siimage() on PPC > >>44x platforms. These 32-bit CPUs have 36-bit physical address and PCI I/O and > >>memory spaces are mapped beyond 4 GB; arch/ppc/ code has a fixup in ioremap() > >>that creates an illusion of the PCI I/O and memory resources being mapped below > >>4 GB, while arch/powerpc/ code got rid of this fixup with PPC 44x having instead > >>CONFIG_RESOURCES_64BIT=y -- this causes the resources to be truncated to 32-bit > >>'unsigned long' type in this driver, and so non-existant memory being ioremap'ed > >>and then accessed... > > >>Thanks to Valentine Barshak for providing an initial patch and explanations. > > >>Signed-off-by: Sergei Shtylyov > > > applied and pushed to Linus, thanks! > > > I guess that it would be worth to audit the rest of IDE code for > > Already done. Some drivers, like sgiioc4, scc_pata, and pmac are prone to > that at least in theory. Although I doubt that they ever get used in such > environments as PPC 44x platform kernels, i.e. 32-bit kernel and PCI mapped > beyond 4 GB. > > > pci_resource_{start,end}() vs 'unsigned long' occurences and fix them. > > There are quite a lot of those overall but they only pose danger if the > resource in question is in memory space since the I/O space always uses > 'unsigned long' addresses. So, IDE core and drivers using only I/O resources > should not be prone to that kind of issue. Thanks for taking a look (good to hear that we are fine for now). > > [ Even if they work at the moment they are just bugs waiting to happened > > when we add support for some new platforms or rewrite the code... ] I still think that it is worth to switch to always using resource_size_t with pci_resource{start,end}() - increase of the code size should be minimal and negligable (also it would happen only for CONFIG_RESOURCES_64BIT=y) but in the return we will keep the code consistent and hint people who're writing new code (and are looking at the existing code as a base). [ this is kernel-wide comment, w.r.t. to IDE - I'll try updating it when I have some time (unless of course somebody sends me a patch earlier :) ] Thanks, Bart