IO resources, x86: ioremap sanity check to catch mapping requests exceeding the BAR sizes

Go through the iomem resource tree to check if any of the ioremap()
requests span more than any slot in the iomem resource tree and do
a WARN_ON() if we hit this check.

This will raise a red-flag, if some driver is mapping more than what
is needed. And hopefully identify possible corruptions much earlier.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index d4b6e6a..c818b45 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -150,6 +150,12 @@
 		return (__force void __iomem *)phys_to_virt(phys_addr);
 
 	/*
+	 * Check if the request spans more than any BAR in the iomem resource
+	 * tree.
+	 */
+	WARN_ON(iomem_map_sanity_check(phys_addr, size));
+
+	/*
 	 * Don't allow anybody to remap normal RAM that we're using..
 	 */
 	for (pfn = phys_addr >> PAGE_SHIFT;