1 files changed, 45 insertions, 6 deletions

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index f5e1a8471714..7b3f2426a1fb 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -159,7 +159,7 @@ EXPORT_SYMBOL(arm_coherent_dma_ops);
 
 static u64 get_coherent_dma_mask(struct device *dev)
 {
-        u64 mask = (u64)arm_dma_limit;
+        u64 mask = (u64)DMA_BIT_MASK(32);
 
         if (dev) {
                 mask = dev->coherent_dma_mask;
@@ -173,10 +173,30 @@ static u64 get_coherent_dma_mask(struct device *dev)
                         return 0;
                 }
 
-                if ((~mask) & (u64)arm_dma_limit) {
-                        dev_warn(dev, "coherent DMA mask %#llx is smaller "
-                                 "than system GFP_DMA mask %#llx\n",
-                                 mask, (u64)arm_dma_limit);
+                /*
+                 * If the mask allows for more memory than we can address,
+                 * and we actually have that much memory, then fail the
+                 * allocation.
+                 */
+                if (sizeof(mask) != sizeof(dma_addr_t) &&
+                    mask > (dma_addr_t)~0 &&
+                    dma_to_pfn(dev, ~0) > arm_dma_pfn_limit) {
+                        dev_warn(dev, "Coherent DMA mask %#llx is larger than dma_addr_t allows\n",
+                                 mask);
+                        dev_warn(dev, "Driver did not use or check the return value from dma_set_coherent_mask()?\n");
+                        return 0;
+                }
+
+                /*
+                 * Now check that the mask, when translated to a PFN,
+                 * fits within the allowable addresses which we can
+                 * allocate.
+                 */
+                if (dma_to_pfn(dev, mask) < arm_dma_pfn_limit) {
+                        dev_warn(dev, "Coherent DMA mask %#llx (pfn %#lx-%#lx) covers a smaller range of system memory than the DMA zone pfn 0x0-%#lx\n",
+                                 mask,
+                                 dma_to_pfn(dev, 0), dma_to_pfn(dev, mask) + 1,
+                                 arm_dma_pfn_limit + 1);
                         return 0;
                 }
         }
@@ -1007,8 +1027,27 @@ void arm_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
  */
 int dma_supported(struct device *dev, u64 mask)
 {
-        if (mask < (u64)arm_dma_limit)
+        unsigned long limit;
+
+        /*
+         * If the mask allows for more memory than we can address,
+         * and we actually have that much memory, then we must
+         * indicate that DMA to this device is not supported.
+         */
+        if (sizeof(mask) != sizeof(dma_addr_t) &&
+            mask > (dma_addr_t)~0 &&
+            dma_to_pfn(dev, ~0) > arm_dma_pfn_limit)
+                return 0;
+
+        /*
+         * Translate the device's DMA mask to a PFN limit.  This
+         * PFN number includes the page which we can DMA to.
+         */
+        limit = dma_to_pfn(dev, mask);
+
+        if (limit < arm_dma_pfn_limit)
                 return 0;
+
         return 1;
 }
 EXPORT_SYMBOL(dma_supported);