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The refactor of powerpc DMA functions in commit6666cc17d7("powerpc/dma: remove dma_nommu_mmap_coherent") incorrectly changes the way DMA mappings are handled on powerpc. Since this change, all mapped pages are marked as cache-inhibited through the default implementation of arch_dma_mmap_pgprot. This differs from the previous behavior of only marking pages in noncoherent mappings as cache-inhibited and has resulted in sporadic system crashes in certain hardware configurations and workloads (see Bugzilla). This commit restores the previous correct behavior by providing an implementation of arch_dma_mmap_pgprot that only marks pages in noncoherent mappings as cache-inhibited. As this behavior should be universal for all powerpc platforms a new file, dma-generic.c, was created to store it. Fixes:6666cc17d7("powerpc/dma: remove dma_nommu_mmap_coherent") # NOTE: fixes commit6666cc17d7released in v5.1. # Consider a stable tag: # Cc: stable@vger.kernel.org # v5.1+ # NOTE: fixes commit6666cc17d7released in v5.1. # Consider a stable tag: # Cc: stable@vger.kernel.org # v5.1+ Cc: stable@vger.kernel.org # v5.1+ Signed-off-by: Shawn Anastasio <shawn@anastas.io> Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20190717235437.12908-1-shawn@anastas.io
18 lines
383 B
C
18 lines
383 B
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Contains common dma routines for all powerpc platforms.
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*
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* Copyright (C) 2019 Shawn Anastasio.
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*/
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#include <linux/mm.h>
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#include <linux/dma-noncoherent.h>
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pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot,
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unsigned long attrs)
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{
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if (!dev_is_dma_coherent(dev))
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return pgprot_noncached(prot);
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return prot;
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}
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