From b34087157dd76e8d96e5e52808134a791ac61e57 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Wed, 21 Nov 2018 16:00:50 +0000 Subject: dma-direct: Make DIRECT_MAPPING_ERROR viable for SWIOTLB With the overflow buffer removed, we no longer have a unique address which is guaranteed not to be a valid DMA target to use as an error token. The DIRECT_MAPPING_ERROR value of 0 tries to at least represent an unlikely DMA target, but unfortunately there are already SWIOTLB users with DMA-able memory at physical address 0 which now gets falsely treated as a mapping failure and leads to all manner of misbehaviour. The best we can do to mitigate that is flip DIRECT_MAPPING_ERROR to the other commonly-used error value of all-bits-set, since the last single byte of memory is by far the least-likely-valid DMA target. Fixes: dff8d6c1ed58 ("swiotlb: remove the overflow buffer") Reported-by: John Stultz Tested-by: John Stultz Acked-by: Konrad Rzeszutek Wilk Signed-off-by: Robin Murphy Signed-off-by: Christoph Hellwig --- include/linux/dma-direct.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h index bd73e7a91410..9e66bfe369aa 100644 --- a/include/linux/dma-direct.h +++ b/include/linux/dma-direct.h @@ -5,7 +5,7 @@ #include #include -#define DIRECT_MAPPING_ERROR 0 +#define DIRECT_MAPPING_ERROR (~(dma_addr_t)0) #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA #include -- cgit v1.2.3-59-g8ed1b