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Commit b3408715 authored by Robin Murphy's avatar Robin Murphy Committed by Christoph Hellwig
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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: dff8d6c1 ("swiotlb: remove the overflow buffer")
Reported-by: default avatarJohn Stultz <john.stultz@linaro.org>
Tested-by: default avatarJohn Stultz <john.stultz@linaro.org>
Acked-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent c8ce94b8
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