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![Robin Murphy](/assets/img/avatar_default.png)
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: dff8d6c1ed
("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>
77 lines
2.6 KiB
C
77 lines
2.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_DMA_DIRECT_H
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#define _LINUX_DMA_DIRECT_H 1
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#include <linux/dma-mapping.h>
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#include <linux/mem_encrypt.h>
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#define DIRECT_MAPPING_ERROR (~(dma_addr_t)0)
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#ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA
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#include <asm/dma-direct.h>
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#else
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static inline dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
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{
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dma_addr_t dev_addr = (dma_addr_t)paddr;
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return dev_addr - ((dma_addr_t)dev->dma_pfn_offset << PAGE_SHIFT);
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}
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static inline phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t dev_addr)
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{
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phys_addr_t paddr = (phys_addr_t)dev_addr;
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return paddr + ((phys_addr_t)dev->dma_pfn_offset << PAGE_SHIFT);
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}
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static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size)
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{
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if (!dev->dma_mask)
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return false;
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return addr + size - 1 <=
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min_not_zero(*dev->dma_mask, dev->bus_dma_mask);
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}
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#endif /* !CONFIG_ARCH_HAS_PHYS_TO_DMA */
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/*
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* If memory encryption is supported, phys_to_dma will set the memory encryption
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* bit in the DMA address, and dma_to_phys will clear it. The raw __phys_to_dma
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* and __dma_to_phys versions should only be used on non-encrypted memory for
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* special occasions like DMA coherent buffers.
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*/
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static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
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{
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return __sme_set(__phys_to_dma(dev, paddr));
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}
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static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
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{
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return __sme_clr(__dma_to_phys(dev, daddr));
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}
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#ifdef CONFIG_ARCH_HAS_DMA_MARK_CLEAN
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void dma_mark_clean(void *addr, size_t size);
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#else
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static inline void dma_mark_clean(void *addr, size_t size)
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{
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}
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#endif /* CONFIG_ARCH_HAS_DMA_MARK_CLEAN */
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u64 dma_direct_get_required_mask(struct device *dev);
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void *dma_direct_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
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gfp_t gfp, unsigned long attrs);
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void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
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dma_addr_t dma_addr, unsigned long attrs);
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void *dma_direct_alloc_pages(struct device *dev, size_t size,
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dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs);
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void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
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dma_addr_t dma_addr, unsigned long attrs);
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dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
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unsigned long offset, size_t size, enum dma_data_direction dir,
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unsigned long attrs);
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int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
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enum dma_data_direction dir, unsigned long attrs);
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int dma_direct_supported(struct device *dev, u64 mask);
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int dma_direct_mapping_error(struct device *dev, dma_addr_t dma_addr);
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#endif /* _LINUX_DMA_DIRECT_H */
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