arm64: Honor __GFP_ZERO in dma allocations

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

Cc: <stable@vger.kernel.org> # v3.14+
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 58e0c2bdde04..ef7d112f5ce0 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
@@ -51,7 +51,7 @@ static int __init early_coherent_pool(char *p)
 }
 early_param("coherent_pool", early_coherent_pool);
 
-static void *__alloc_from_pool(size_t size, struct page **ret_page)
+static void *__alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags)
 {
         unsigned long val;
         void *ptr = NULL;
@@ -67,6 +67,8 @@ static void *__alloc_from_pool(size_t size, struct page **ret_page)
 
                 *ret_page = phys_to_page(phys);
                 ptr = (void *)val;
+                if (flags & __GFP_ZERO)
+                        memset(ptr, 0, size);
         }
 
         return ptr;
@@ -101,6 +103,7 @@ static void *__dma_alloc_coherent(struct device *dev, size_t size,
                 flags |= GFP_DMA;
         if (IS_ENABLED(CONFIG_DMA_CMA) && (flags & __GFP_WAIT)) {
                 struct page *page;
+                void *addr;
 
                 size = PAGE_ALIGN(size);
                 page = dma_alloc_from_contiguous(dev, size >> PAGE_SHIFT,
@@ -109,7 +112,10 @@ 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);
         }
@@ -146,7 +152,7 @@ static void *__dma_alloc(struct device *dev, size_t size,
 
         if (!coherent && !(flags & __GFP_WAIT)) {
                 struct page *page = NULL;
-                void *addr = __alloc_from_pool(size, &page);
+                void *addr = __alloc_from_pool(size, &page, flags);
 
                 if (addr)
                         *dma_handle = phys_to_dma(dev, page_to_phys(page));