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arm64: dma-mapping: clear buffers allocated with FORCE_CONTIGUOUS flag 

dma_alloc_*() buffers might be exposed to userspace via mmap() call, so
they should be cleared on allocation. In case of IOMMU-based dma-mapping
implementation such buffer clearing was missing in the code path for
DMA_ATTR_FORCE_CONTIGUOUS flag handling, because dma_alloc_from_contiguous()
doesn't honor __GFP_ZERO flag. This patch fixes this issue. For more
information on clearing buffers allocated by dma_alloc_* functions,
see commit 6829e274a6 ("arm64: dma-mapping: always clear allocated
buffers").

Fixes: 44176bb38f ("arm64: Add support for DMA_ATTR_FORCE_CONTIGUOUS to IOMMU")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Marek Szyprowski 2018-06-12 13:08:40 +02:00 committed by Catalin Marinas
parent ce397d215c
commit dd65a941f6
1 changed files with 5 additions and 4 deletions
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9
arch/arm64/mm/dma-mapping.c
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@ -583,13 +583,14 @@ static void *__iommu_alloc_attrs(struct device *dev, size_t size,
size >> PAGE_SHIFT);
return NULL;
}
if (!coherent)
__dma_flush_area(page_to_virt(page), iosize);
addr = dma_common_contiguous_remap(page, size, VM_USERMAP,
prot,
__builtin_return_address(0));
if (!addr) {
if (addr) {
memset(addr, 0, size);
if (!coherent)
__dma_flush_area(page_to_virt(page), iosize);
} else {
iommu_dma_unmap_page(dev, *handle, iosize, 0, attrs);
dma_release_from_contiguous(dev, page,
size >> PAGE_SHIFT);