From 9b483417527f2e47985856867c5716df013227c7 Mon Sep 17 00:00:00 2001 From: Andreas Mohr Date: Thu, 7 Dec 2006 02:14:00 +0100 Subject: [PATCH] [PATCH] i386: fix buggy MTRR address checks 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. TBD Note that my patch is pretty much UNTESTED, since I can only verify that it TBD successfully boots my machine, but I cannot test against actual buggy TBD hardware which would require these (formerly broken) checks. Long -mm TBD simmering would make sense, especially since these now-working checks might TBD turn out to have adverse effects on unaffected hardware. Signed-off-by: Andreas Mohr Signed-off-by: Andi Kleen Acked-by: Jan Beulich Cc: Andi Kleen Signed-off-by: Andrew Morton --- arch/i386/kernel/cpu/mtrr/generic.c | 4 ++-- arch/i386/kernel/cpu/mtrr/main.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/i386/kernel/cpu/mtrr/generic.c b/arch/i386/kernel/cpu/mtrr/generic.c index 0b61eed8bbd..ee8dc675395 100644 --- a/arch/i386/kernel/cpu/mtrr/generic.c +++ b/arch/i386/kernel/cpu/mtrr/generic.c @@ -366,7 +366,7 @@ int generic_validate_add_page(unsigned long base, unsigned long size, unsigned i 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 @@ int generic_validate_add_page(unsigned long base, unsigned long size, unsigned i } } - 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 --git a/arch/i386/kernel/cpu/mtrr/main.c b/arch/i386/kernel/cpu/mtrr/main.c index fff90bda473..2b8b0b361cc 100644 --- a/arch/i386/kernel/cpu/mtrr/main.c +++ b/arch/i386/kernel/cpu/mtrr/main.c @@ -263,8 +263,8 @@ static void set_mtrr(unsigned int reg, unsigned long base, /** * 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 * -- 2.20.1