Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'dma-mapping-5.17-1' of git://git.infradead.org/users/hch/dma-mapping
Pull dma-mapping fix from Christoph Hellwig:
- fix a swiotlb info leak (Halil Pasic)
* tag 'dma-mapping-5.17-1' of git://git.infradead.org/users/hch/dma-mapping:
swiotlb: fix info leak with DMA_FROM_DEVICE
+18
-1
+8
Documentation/core-api/dma-attributes.rst
+8
Documentation/core-api/dma-attributes.rst
···
130
130
subsystem that the buffer is fully accessible at the elevated privilege
131
131
level (and ideally inaccessible or at least read-only at the
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132
lesser-privileged levels).
133
+
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+
DMA_ATTR_OVERWRITE
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+
------------------
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+
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+
This is a hint to the DMA-mapping subsystem that the device is expected to
138
+
overwrite the entire mapped size, thus the caller does not require any of the
139
+
previous buffer contents to be preserved. This allows bounce-buffering
140
+
implementations to optimise DMA_FROM_DEVICE transfers.
+8
include/linux/dma-mapping.h
+8
include/linux/dma-mapping.h
···
62
62
#define DMA_ATTR_PRIVILEGED (1UL << 9)
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64
/*
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+
* This is a hint to the DMA-mapping subsystem that the device is expected
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+
* to overwrite the entire mapped size, thus the caller does not require any
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+
* of the previous buffer contents to be preserved. This allows
68
+
* bounce-buffering implementations to optimise DMA_FROM_DEVICE transfers.
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+
*/
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+
#define DMA_ATTR_OVERWRITE (1UL << 10)
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+
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+
/*
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* A dma_addr_t can hold any valid DMA or bus address for the platform. It can
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74
* be given to a device to use as a DMA source or target. It is specific to a
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75
* given device and there may be a translation between the CPU physical address
+2
-1
kernel/dma/swiotlb.c
+2
-1
kernel/dma/swiotlb.c
···
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628
mem->slots[index + i].orig_addr = slot_addr(orig_addr, i);
629
629
tlb_addr = slot_addr(mem->start, index) + offset;
630
630
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&
631
-
(dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))
631
+
(!(attrs & DMA_ATTR_OVERWRITE) || dir == DMA_TO_DEVICE ||
632
+
dir == DMA_BIDIRECTIONAL))
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633
swiotlb_bounce(dev, tlb_addr, mapping_size, DMA_TO_DEVICE);
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return tlb_addr;
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635
}