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dma-mapping: add a dma_alloc_need_uncached helper 

Check if we need to allocate uncached memory for a device given the
allocation flags.  Switch over the uncached segment check to this helper
to deal with architectures that do not support the dma_cache_sync
operation and thus should not returned cacheable memory for
DMA_ATTR_NON_CONSISTENT allocations.

Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Christoph Hellwig 2019-06-14 16:06:10 +02:00
parent 961729bfc7
commit 4b85faed21
2 changed files with 16 additions and 2 deletions
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14
include/linux/dma-noncoherent.h
View File

@ -20,6 +20,20 @@ static inline bool dev_is_dma_coherent(struct device *dev)
}
#endif /* CONFIG_ARCH_HAS_DMA_COHERENCE_H */
/*
* Check if an allocation needs to be marked uncached to be coherent.
*/
static inline bool dma_alloc_need_uncached(struct device *dev,
unsigned long attrs)
{
if (dev_is_dma_coherent(dev))
return false;
if (IS_ENABLED(CONFIG_DMA_NONCOHERENT_CACHE_SYNC) &&
(attrs & DMA_ATTR_NON_CONSISTENT))
return false;
return true;
}
void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
gfp_t gfp, unsigned long attrs);
void arch_dma_free(struct device *dev, size_t size, void *cpu_addr,

4
kernel/dma/direct.c
View File

@ -160,7 +160,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
memset(ret, 0, size);
if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&
!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_NON_CONSISTENT)) {
dma_alloc_need_uncached(dev, attrs)) {
arch_dma_prep_coherent(page, size);
ret = uncached_kernel_address(ret);
}
@ -182,7 +182,7 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&
!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_NON_CONSISTENT))
dma_alloc_need_uncached(dev, attrs))
cpu_addr = cached_kernel_address(cpu_addr);
__dma_direct_free_pages(dev, size, virt_to_page(cpu_addr));
}