From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932105AbWJCMz4 (ORCPT ); Tue, 3 Oct 2006 08:55:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932118AbWJCMz4 (ORCPT ); Tue, 3 Oct 2006 08:55:56 -0400 Received: from rhlx01.fht-esslingen.de ([129.143.116.10]:59587 "EHLO rhlx01.fht-esslingen.de") by vger.kernel.org with ESMTP id S932103AbWJCMzz (ORCPT ); Tue, 3 Oct 2006 08:55:55 -0400 Date: Tue, 3 Oct 2006 14:55:53 +0200 From: Andreas Mohr To: Andrew Morton Cc: rgooch@atnf.csiro.au, Jan Beulich , Kurt Garloff , linux-kernel@vger.kernel.org Subject: [PATCH -mm] fix buggy MTRR address checks Message-ID: <20061003125553.GA3648@rhlx01.fht-esslingen.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.1i X-Priority: none Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Fix checks that failed to realize that values are 4-kB-unit-sized (note the format strings in this same diff context which *do* realize the unit size, via appended "000"!). Also fix an incorrect below-1MB area check (as gathered from Jan Beulich's unapplied patch at http://www.ussg.iu.edu/hypermail/linux/kernel/0411.1/1378.html ) Update mtrr_add_page() docu to make 4-kB-sized calculation more obvious. Given several further items mentioned in Jan's patch mail, all in all MTRR code seems surprisingly buggy, for a surprisingly long period of time (many years). Further work/investigation would be useful. Note that my patch is pretty much UNTESTED, since I can only verify that it successfully boots my machine, but I cannot test against actual buggy hardware which would require these (formerly broken) checks. Long -mm simmering would make sense, especially since these now-working checks might turn out to have adverse effects on unaffected hardware. Signed-off-by: Andreas Mohr diff -urN linux-2.6.18-mm3.orig/arch/i386/kernel/cpu/mtrr/generic.c linux-2.6.18-mm3/arch/i386/kernel/cpu/mtrr/generic.c --- linux-2.6.18-mm3.orig/arch/i386/kernel/cpu/mtrr/generic.c 2006-10-11 11:59:45.000000000 +0200 +++ linux-2.6.18-mm3/arch/i386/kernel/cpu/mtrr/generic.c 2006-10-11 12:04:37.000000000 +0200 @@ -366,7 +366,7 @@ printk(KERN_WARNING "mtrr: base(0x%lx000) is not 4 MiB aligned\n", base); return -EINVAL; } - if (!(base + size < 0x70000000 || base > 0x7003FFFF) && + if (!(base + size < 0x70000 || base > 0x7003F) && (type == MTRR_TYPE_WRCOMB || type == MTRR_TYPE_WRBACK)) { printk(KERN_WARNING "mtrr: writable mtrr between 0x70000000 and 0x7003FFFF may hang the CPU.\n"); @@ -374,7 +374,7 @@ } } - if (base + size < 0x100) { + if (base < 0x100) { printk(KERN_WARNING "mtrr: cannot set region below 1 MiB (0x%lx000,0x%lx000)\n", base, size); return -EINVAL; diff -urN linux-2.6.18-mm3.orig/arch/i386/kernel/cpu/mtrr/main.c linux-2.6.18-mm3/arch/i386/kernel/cpu/mtrr/main.c --- linux-2.6.18-mm3.orig/arch/i386/kernel/cpu/mtrr/main.c 2006-08-18 20:03:00.000000000 +0200 +++ linux-2.6.18-mm3/arch/i386/kernel/cpu/mtrr/main.c 2006-10-11 12:04:37.000000000 +0200 @@ -263,8 +263,8 @@ /** * mtrr_add_page - Add a memory type region - * @base: Physical base address of region in pages (4 KB) - * @size: Physical size of region in pages (4 KB) + * @base: Physical base address of region in pages (in units of 4 kB!) + * @size: Physical size of region in pages (4 kB) * @type: Type of MTRR desired * @increment: If this is true do usage counting on the region *