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dma-direct: Make DIRECT_MAPPING_ERROR viable for SWIOTLB

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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>
This commit is contained in:
Robin Murphy 2018-11-21 16:00:50 +00:00 committed by Christoph Hellwig
parent c8ce94b8fe
commit b34087157d
1 changed files with 1 additions and 1 deletions
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2
include/linux/dma-direct.h
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@ -5,7 +5,7 @@
#include <linux/dma-mapping.h> #include <linux/dma-mapping.h>
#include <linux/mem_encrypt.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 #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
#include <asm/dma-direct.h> #include <asm/dma-direct.h>