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dma-mapping: truncate dma masks to what dma_addr_t can hold

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The dma masks in struct device are always 64-bits wide.  But for builds
using a 32-bit dma_addr_t we need to ensure we don't store an
unsupportable value.  Before Linux 5.0 this was handled at least by
the ARM dma mapping code by never allowing to set a larger dma_mask,
but these days we allow the driver to just set the largest supported
value and never fall back to a smaller one.  Ensure this always works
by truncating the value.

Fixes: 9eb9e96e97 ("Documentation/DMA-API-HOWTO: update dma_mask sections")
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Christoph Hellwig 2019-04-29 09:16:42 -05:00
parent 591fcf3b30
commit 4a54d16f61
1 changed files with 12 additions and 0 deletions
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12
kernel/dma/mapping.c
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@ -317,6 +317,12 @@ void arch_dma_set_mask(struct device *dev, u64 mask);
int dma_set_mask(struct device *dev, u64 mask)
{
/*
* Truncate the mask to the actually supported dma_addr_t width to
* avoid generating unsupportable addresses.
*/
mask = (dma_addr_t)mask;
if (!dev->dma_mask || !dma_supported(dev, mask))
return -EIO;
@ -330,6 +336,12 @@ EXPORT_SYMBOL(dma_set_mask);
#ifndef CONFIG_ARCH_HAS_DMA_SET_COHERENT_MASK
int dma_set_coherent_mask(struct device *dev, u64 mask)
{
/*
* Truncate the mask to the actually supported dma_addr_t width to
* avoid generating unsupportable addresses.
*/
mask = (dma_addr_t)mask;
if (!dma_supported(dev, mask))
return -EIO;