kmemcheck: add DMA hooks

This patch hooks into the DMA API to prevent the reporting of the
false positives that would otherwise be reported when memory is
accessed that is also used directly by devices.

[rebased for mainline inclusion]
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>

arch/x86/include/asm/dma-mapping.h

@@ -6,6 +6,7 @@
  * Documentation/DMA-API.txt for documentation.
  */
 
+#include <linux/kmemcheck.h>
 #include <linux/scatterlist.h>
 #include <linux/dma-debug.h>
 #include <linux/dma-attrs.h>
@@ -60,6 +61,7 @@ dma_map_single(struct device *hwdev, void *ptr, size_t size,
 	dma_addr_t addr;
 
 	BUG_ON(!valid_dma_direction(dir));
+	kmemcheck_mark_initialized(ptr, size);
 	addr = ops->map_page(hwdev, virt_to_page(ptr),
 			     (unsigned long)ptr & ~PAGE_MASK, size,
 			     dir, NULL);