Commit 98f3e84f authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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
parents 6676ba2a ddbd89de

Documentation/core-api/dma-attributes.rst

+8 −0
Original line number Diff line number Diff line
@@ -130,3 +130,11 @@ accesses to DMA buffers in both privileged "supervisor" and unprivileged 
subsystem that the buffer is fully accessible at the elevated privilege

level (and ideally inaccessible or at least read-only at the

lesser-privileged levels).



DMA_ATTR_OVERWRITE

------------------



This is a hint to the DMA-mapping subsystem that the device is expected to

overwrite the entire mapped size, thus the caller does not require any of the

previous buffer contents to be preserved. This allows bounce-buffering

implementations to optimise DMA_FROM_DEVICE transfers.

include/linux/dma-mapping.h

+8 −0
Original line number Diff line number Diff line
@@ -61,6 +61,14 @@ 
 */

#define DMA_ATTR_PRIVILEGED		(1UL << 9)



/*

 * This is a hint to the DMA-mapping subsystem that the device is expected

 * to overwrite the entire mapped size, thus the caller does not require any

 * of the previous buffer contents to be preserved. This allows

 * bounce-buffering implementations to optimise DMA_FROM_DEVICE transfers.

 */

#define DMA_ATTR_OVERWRITE		(1UL << 10)



/*

 * A dma_addr_t can hold any valid DMA or bus address for the platform.  It can

 * be given to a device to use as a DMA source or target.  It is specific to a

kernel/dma/swiotlb.c

+2 −1
Original line number Diff line number Diff line
@@ -628,7 +628,8 @@ phys_addr_t swiotlb_tbl_map_single(struct device *dev, phys_addr_t orig_addr, 
		mem->slots[index + i].orig_addr = slot_addr(orig_addr, i);

	tlb_addr = slot_addr(mem->start, index) + offset;

	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC) &&

	    (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL))

	    (!(attrs & DMA_ATTR_OVERWRITE) || dir == DMA_TO_DEVICE ||

	    dir == DMA_BIDIRECTIONAL))

		swiotlb_bounce(dev, tlb_addr, mapping_size, DMA_TO_DEVICE);

	return tlb_addr;

}