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dma-direct: provide generic support for uncached kernel segments

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A few architectures support uncached kernel segments.  In that case we get
an uncached mapping for a given physica address by using an offset in the
uncached segement.  Implement support for this scheme in the generic
dma-direct code instead of duplicating it in arch hooks.

Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Christoph Hellwig 2019-06-03 08:43:51 +02:00
parent 67f30ad19c
commit c30700db9e
3 changed files with 26 additions and 2 deletions
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8
arch/Kconfig
View File

@ -260,6 +260,14 @@ config ARCH_HAS_SET_MEMORY
config ARCH_HAS_SET_DIRECT_MAP
bool
#
# Select if arch has an uncached kernel segment and provides the
# uncached_kernel_address / cached_kernel_address symbols to use it
#
config ARCH_HAS_UNCACHED_SEGMENT
select ARCH_HAS_DMA_PREP_COHERENT
bool
# Select if arch init_task must go in the __init_task_data section
config ARCH_TASK_STRUCT_ON_STACK
bool

3
include/linux/dma-noncoherent.h
View File

@ -80,4 +80,7 @@ static inline void arch_dma_prep_coherent(struct page *page, size_t size)
}
#endif /* CONFIG_ARCH_HAS_DMA_PREP_COHERENT */
void *uncached_kernel_address(void *addr);
void *cached_kernel_address(void *addr);
#endif /* _LINUX_DMA_NONCOHERENT_H */

17
kernel/dma/direct.c
View File

@ -158,6 +158,13 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
*dma_handle = phys_to_dma(dev, page_to_phys(page));
}
memset(ret, 0, size);
if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&
!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_NON_CONSISTENT)) {
arch_dma_prep_coherent(page, size);
ret = uncached_kernel_address(ret);
}
return ret;
}
@ -173,13 +180,18 @@ void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
if (force_dma_unencrypted())
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))
cpu_addr = cached_kernel_address(cpu_addr);
__dma_direct_free_pages(dev, size, virt_to_page(cpu_addr));
}
void *dma_direct_alloc(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
{
if (!dev_is_dma_coherent(dev))
if (!IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&
!dev_is_dma_coherent(dev))
return arch_dma_alloc(dev, size, dma_handle, gfp, attrs);
return dma_direct_alloc_pages(dev, size, dma_handle, gfp, attrs);
}
@ -187,7 +199,8 @@ void *dma_direct_alloc(struct device *dev, size_t size,
void dma_direct_free(struct device *dev, size_t size,
void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs)
{
if (!dev_is_dma_coherent(dev))
if (!IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) &&
!dev_is_dma_coherent(dev))
arch_dma_free(dev, size, cpu_addr, dma_addr, attrs);
else
dma_direct_free_pages(dev, size, cpu_addr, dma_addr, attrs);