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| author |   Robin Murphy <robin.murphy@arm.com> | 2018-11-21 16:00:50 +0000 |
|---|---|---|
| committer |   Christoph Hellwig <hch@lst.de> | 2018-11-21 18:47:52 +0100 |
| commit | b34087157dd76e8d96e5e52808134a791ac61e57 (patch) | |
| tree | 94aba2a4c0adae46be45c150ff5a57f15805d882 /include | |
| parent | Merge tag 'mips_fixes_4.20_3' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux (diff) | |
| download | linux-dev-b34087157dd76e8d96e5e52808134a791ac61e57.tar.xz linux-dev-b34087157dd76e8d96e5e52808134a791ac61e57.zip | |
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')
| -rw-r--r-- | include/linux/dma-direct.h | 2 |
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> |