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518a2f1925
If we want to map memory from the DMA allocator to userspace it must be zeroed at allocation time to prevent stale data leaks. We already do this on most common architectures, but some architectures don't do this yet, fix them up, either by passing GFP_ZERO when we use the normal page allocator or doing a manual memset otherwise. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k] Acked-by: Sam Ravnborg <sam@ravnborg.org> [sparc]
60 lines
1.4 KiB
C
60 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* DMA operations that map to virtual addresses without flushing memory.
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*/
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#include <linux/export.h>
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#include <linux/mm.h>
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#include <linux/dma-mapping.h>
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#include <linux/scatterlist.h>
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static void *dma_virt_alloc(struct device *dev, size_t size,
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dma_addr_t *dma_handle, gfp_t gfp,
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unsigned long attrs)
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{
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void *ret;
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ret = (void *)__get_free_pages(gfp | __GFP_ZERO, get_order(size));
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if (ret)
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*dma_handle = (uintptr_t)ret;
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return ret;
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}
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static void dma_virt_free(struct device *dev, size_t size,
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void *cpu_addr, dma_addr_t dma_addr,
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unsigned long attrs)
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{
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free_pages((unsigned long)cpu_addr, get_order(size));
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}
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static dma_addr_t dma_virt_map_page(struct device *dev, struct page *page,
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unsigned long offset, size_t size,
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enum dma_data_direction dir,
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unsigned long attrs)
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{
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return (uintptr_t)(page_address(page) + offset);
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}
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static int dma_virt_map_sg(struct device *dev, struct scatterlist *sgl,
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int nents, enum dma_data_direction dir,
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unsigned long attrs)
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{
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int i;
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struct scatterlist *sg;
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for_each_sg(sgl, sg, nents, i) {
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BUG_ON(!sg_page(sg));
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sg_dma_address(sg) = (uintptr_t)sg_virt(sg);
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sg_dma_len(sg) = sg->length;
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}
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return nents;
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}
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const struct dma_map_ops dma_virt_ops = {
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.alloc = dma_virt_alloc,
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.free = dma_virt_free,
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.map_page = dma_virt_map_page,
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.map_sg = dma_virt_map_sg,
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};
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EXPORT_SYMBOL(dma_virt_ops);
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