1 files changed, 10 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 95edad4faf26..c50d7072f305 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -76,6 +76,7 @@ static unsigned long iommu_range_alloc(struct iommu_table *tbl,
                                        unsigned int align_order)
 { 
         unsigned long n, end, i, start;
+        unsigned long start_addr, end_addr;
         unsigned long limit;
         int largealloc = npages > 15;
         int pass = 0;
@@ -146,6 +147,15 @@ static unsigned long iommu_range_alloc(struct iommu_table *tbl,
                 }
         }
 
+        /* DMA cannot cross 4 GB boundary */
+        start_addr = (n + tbl->it_offset) << PAGE_SHIFT;
+        end_addr = (end + tbl->it_offset) << PAGE_SHIFT;
+        if ((start_addr >> 32) != (end_addr >> 32)) {
+                end_addr &= 0xffffffff00000000l;
+                start = (end_addr >> PAGE_SHIFT) - tbl->it_offset;
+                goto again;
+        }
+
         for (i = n; i < end; i++)
                 if (test_bit(i, tbl->it_map)) {
                         start = i+1;