From: Andi Kleen <ak@linux.intel.com>
Date: Fri, 15 Aug 2008 16:12:47 +0000 (+0200)
Subject: x86: Fix ioremap off by one BUG
X-Git-Tag: v2.6.27-rc4~59^2~1^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e213e87785559eaf3107897226817aea9291b06f;p=pandora-kernel.git

x86: Fix ioremap off by one BUG

Jean Delvare's machine triggered this BUG

acpi_os_map_memory phys ffff0000 size 65535
------------[ cut here ]------------
kernel BUG at arch/x86/mm/pat.c:233!

with ACPI in the backtrace.

Adding some debugging output showed that ACPI calls

acpi_os_map_memory phys ffff0000 size 65535

And ioremap/PAT does this check in 32bit, so addr+size wraps and the BUG
in reserve_memtype() triggers incorrectly.

        BUG_ON(start >= end); /* end is exclusive */

But reserve_memtype already uses u64:

int reserve_memtype(u64 start, u64 end,

so the 32bit truncation must happen in the caller. Presumably in ioremap
when it passes this information to reserve_memtype().

This patch does this computation in 64bit.

http://bugzilla.kernel.org/show_bug.cgi?id=11346

Signed-off-by: Andi Kleen <ak@linux.intel.com>
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