parisc: don't set ARCH_NO_COHERENT_DMA_MMAP (5128da32) · Commits · 戴 / test

parisc is the only architecture that sets ARCH_NO_COHERENT_DMA_MMAP when an MMU is enabled. AFAIK this is because parisc CPUs use VIVT caches, which means exporting normally cachable memory to userspace is relatively dangrous due to cache aliasing. But normally cachable memory is only allocated by dma_alloc_coherent on parisc when using the sba_iommu or ccio_iommu drivers, so just remove the .mmap implementation for them so that we don't have to set ARCH_NO_COHERENT_DMA_MMAP, which I plan to get rid of. Signed-off-by:

Christoph Hellwig <hch@lst.de>

arch/parisc/Kconfig

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Original line number	Diff line number	Diff line
		@@ -52,7 +52,6 @@ config PARISC
		select GENERIC_SCHED_CLOCK
		select HAVE_UNSTABLE_SCHED_CLOCK if SMP
		select GENERIC_CLOCKEVENTS
		select ARCH_NO_COHERENT_DMA_MMAP
		select CPU_NO_EFFICIENT_FFS
		select NEED_DMA_MAP_STATE
		select NEED_SG_DMA_LENGTH

drivers/parisc/ccio-dma.c

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Original line number	Diff line number	Diff line
		@@ -1024,7 +1024,6 @@ static const struct dma_map_ops ccio_ops = {
		.unmap_page = ccio_unmap_page,
		.map_sg = ccio_map_sg,
		.unmap_sg = ccio_unmap_sg,
		.mmap = dma_common_mmap,
		.get_sgtable = dma_common_get_sgtable,
		};

drivers/parisc/sba_iommu.c

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Original line number	Diff line number	Diff line
		@@ -1084,7 +1084,6 @@ static const struct dma_map_ops sba_ops = {
		.unmap_page = sba_unmap_page,
		.map_sg = sba_map_sg,
		.unmap_sg = sba_unmap_sg,
		.mmap = dma_common_mmap,
		.get_sgtable = dma_common_get_sgtable,
		};

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