[PATCH 3.16.y-ckt 067/144] arm64: Honor __GFP_ZERO in dma allocations

[Luis Henriques]

3.16.7-ckt10 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Suzuki K. Poulose" <suzuki.poulose at arm.com>

commit 7132813c384515c9dede1ae20e56f3895feb7f1e upstream.

Current implementation doesn't zero out the pages allocated.
Honor the __GFP_ZERO flag and zero out if set.

Acked-by: Will Deacon <will.deacon at arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose at arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas at arm.com>
[ luis: backported to 3.16: based on Suzuki's 3.14 backport ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/arm64/mm/dma-mapping.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 4164c5ace9f8..de3abbe6c59f 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -55,6 +55,7 @@ static void *__dma_alloc_coherent(struct device *dev, size_t size,
 		flags |= GFP_DMA;
 	if (IS_ENABLED(CONFIG_DMA_CMA)) {
 		struct page *page;
+		void *addr;
 
 		size = PAGE_ALIGN(size);
 		page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
@@ -63,7 +64,10 @@ static void *__dma_alloc_coherent(struct device *dev, size_t size,
 			return NULL;
 
 		*dma_handle = phys_to_dma(dev, page_to_phys(page));
-		return page_address(page);
+		addr = page_address(page);
+		if (flags & __GFP_ZERO)
+			memset(addr, 0, size);
+		return addr;
 	} else {
 		return swiotlb_alloc_coherent(dev, size, dma_handle, flags);
 	}