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* dma-mapping: fix page attributes for dma_mmap_*Christoph Hellwig2019-08-101-17/+0Star
| | | | | | | | | | | | | | | | | | | | | | All the way back to introducing dma_common_mmap we've defaulted to mark the pages as uncached. But this is wrong for DMA coherent devices. Later on DMA_ATTR_WRITE_COMBINE also got incorrect treatment as that flag is only treated special on the alloc side for non-coherent devices. Introduce a new dma_pgprot helper that deals with the check for coherent devices so that only the remapping cases ever reach arch_dma_mmap_pgprot and we thus ensure no aliasing of page attributes happens, which makes the powerpc version of arch_dma_mmap_pgprot obsolete and simplifies the remaining ones. Note that this means arch_dma_mmap_pgprot is a bit misnamed now, but we'll phase it out soon. Fixes: 64ccc9c033c6 ("common: dma-mapping: add support for generic dma_mmap_* calls") Reported-by: Shawn Anastasio <shawn@anastas.io> Reported-by: Gavin Li <git@thegavinli.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Catalin Marinas <catalin.marinas@arm.com> # arm64
* powerpc/dma: Fix invalid DMA mmap behaviorShawn Anastasio2019-07-191-0/+17
The refactor of powerpc DMA functions in commit 6666cc17d780 ("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: 6666cc17d780 ("powerpc/dma: remove dma_nommu_mmap_coherent") # NOTE: fixes commit 6666cc17d780 released in v5.1. # Consider a stable tag: # Cc: stable@vger.kernel.org # v5.1+ # NOTE: fixes commit 6666cc17d780 released 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