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>

2 files changed, 18 insertions, 0 deletions

diff --git a/arch/x86/include/asm/dma-mapping.h b/arch/x86/include/asm/dma-mapping.h
index f82fdc412c64..d57d0c1857bc 100644
--- a/arch/x86/include/asm/dma-mapping.h
+++ b/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);
diff --git a/include/linux/kmemcheck.h b/include/linux/kmemcheck.h
index 5b65f4ebeadf..71f21ae33d1d 100644
--- a/include/linux/kmemcheck.h
+++ b/include/linux/kmemcheck.h
@@ -59,6 +59,22 @@ static inline bool kmemcheck_page_is_tracked(struct page *p)
 {
         return false;
 }
+
+static inline void kmemcheck_mark_unallocated(void *address, unsigned int n)
+{
+}
+
+static inline void kmemcheck_mark_uninitialized(void *address, unsigned int n)
+{
+}
+
+static inline void kmemcheck_mark_initialized(void *address, unsigned int n)
+{
+}
+
+static inline void kmemcheck_mark_freed(void *address, unsigned int n)
+{
+}
 #endif /* CONFIG_KMEMCHECK */
 
 #endif /* LINUX_KMEMCHECK_H */