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>

arch/x86/mm/ioremap.c

@@ -170,7 +170,7 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
 	phys_addr &= PAGE_MASK;
 	size = PAGE_ALIGN(last_addr+1) - phys_addr;
 
-	retval = reserve_memtype(phys_addr, phys_addr + size,
+	retval = reserve_memtype(phys_addr, (u64)phys_addr + size,
 						prot_val, &new_prot_val);
 	if (retval) {
 		pr_debug("Warning: reserve_memtype returned %d\n", retval);