ARM: dma-mapping: don't allow DMA mappings to be marked executable

commit 0ea1ec71 upstream.

DMA mapping permissions were being derived from pgprot_kernel directly
without using PAGE_KERNEL.  This causes them to be marked with executable
permission, which is not what we want.  Fix this.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

arch/arm/mm/dma-mapping.c

@@ -374,7 +374,7 @@ dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gf
 		return memory;
 
 	return __dma_alloc(dev, size, handle, gfp,
-			   pgprot_dmacoherent(pgprot_kernel));
+			   pgprot_dmacoherent(PAGE_KERNEL));
 }
 EXPORT_SYMBOL(dma_alloc_coherent);
 
@@ -386,7 +386,7 @@ void *
 dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 {
 	return __dma_alloc(dev, size, handle, gfp,
-			   pgprot_writecombine(pgprot_kernel));
+			   pgprot_writecombine(PAGE_KERNEL));
 }
 EXPORT_SYMBOL(dma_alloc_writecombine);