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authorRobin Murphy <robin.murphy@arm.com>2018-11-21 19:00:50 +0300
committerChristoph Hellwig <hch@lst.de>2018-11-21 20:47:52 +0300
commitb34087157dd76e8d96e5e52808134a791ac61e57 (patch)
tree94aba2a4c0adae46be45c150ff5a57f15805d882 /include/linux/dma-direct.h
parentc8ce94b8fe5324aca4c10baeb53dea2d5775a170 (diff)
downloadlinux-b34087157dd76e8d96e5e52808134a791ac61e57.tar.xz
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 <john.stultz@linaro.org> Tested-by: John Stultz <john.stultz@linaro.org> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'include/linux/dma-direct.h')
-rw-r--r--include/linux/dma-direct.h2
1 files changed, 1 insertions, 1 deletions
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 <linux/dma-mapping.h>
#include <linux/mem_encrypt.h>
-#define DIRECT_MAPPING_ERROR 0
+#define DIRECT_MAPPING_ERROR (~(dma_addr_t)0)
#ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
#include <asm/dma-direct.h>