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| author | Christoph Hellwig <hch@lst.de> | 2019-07-26 09:26:40 +0200 |
|---|---|---|
| committer | Christoph Hellwig <hch@lst.de> | 2019-08-10 19:52:45 +0200 |
| commit | 33dcb37cef741294b481f4d889a465b8091f11bf (patch) | |
| tree | 129f9cde5b52cd77e04382c99ff0421aa862354b /include/linux/dma-noncoherent.h | |
| parent | d8ad55538abe443919e20e0bb996561bca9cad84 (diff) | |
| download | lwn-33dcb37cef741294b481f4d889a465b8091f11bf.tar.gz lwn-33dcb37cef741294b481f4d889a465b8091f11bf.zip | |
dma-mapping: fix page attributes for dma_mmap_*
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
Diffstat (limited to 'include/linux/dma-noncoherent.h')
| -rw-r--r-- | include/linux/dma-noncoherent.h | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h index 3813211a9aad..0bff3d7fac92 100644 --- a/include/linux/dma-noncoherent.h +++ b/include/linux/dma-noncoherent.h @@ -42,13 +42,18 @@ void arch_dma_free(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs); long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr, dma_addr_t dma_addr); - -#ifdef CONFIG_ARCH_HAS_DMA_MMAP_PGPROT pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs); + +#ifdef CONFIG_MMU +pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs); #else -# define arch_dma_mmap_pgprot(dev, prot, attrs) pgprot_noncached(prot) -#endif +static inline pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, + unsigned long attrs) +{ + return prot; /* no protection bits supported without page tables */ +} +#endif /* CONFIG_MMU */ #ifdef CONFIG_DMA_NONCOHERENT_CACHE_SYNC void arch_dma_cache_sync(struct device *dev, void *vaddr, size_t size, |