Messages in this thread | | | Subject | Re: [PATCH 1/9] dma-direct: provide page based alloc/free helpers | From | Robin Murphy <> | Date | Fri, 30 Nov 2018 19:04:41 +0000 |
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On 05/11/2018 12:19, Christoph Hellwig wrote: > Some architectures support remapping highmem into DMA coherent > allocations. To use the common code for them we need variants of > dma_direct_{alloc,free}_pages that do not use kernel virtual addresses.
FWIW it's as much about non-cacheable remapping of lowmem as it is about highmem. Regardless, the diff looks OK to me.
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de> > --- > include/linux/dma-direct.h | 3 +++ > kernel/dma/direct.c | 32 ++++++++++++++++++++++---------- > 2 files changed, 25 insertions(+), 10 deletions(-) > > diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h > index bd73e7a91410..5a7a3bbb912f 100644 > --- a/include/linux/dma-direct.h > +++ b/include/linux/dma-direct.h > @@ -67,6 +67,9 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, > dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs); > void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr, > dma_addr_t dma_addr, unsigned long attrs); > +struct page *__dma_direct_alloc_pages(struct device *dev, size_t size, > + dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs); > +void __dma_direct_free_pages(struct device *dev, size_t size, struct page *page); > dma_addr_t dma_direct_map_page(struct device *dev, struct page *page, > unsigned long offset, size_t size, enum dma_data_direction dir, > unsigned long attrs); > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 22a12ab5a5e9..680287779b0a 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -103,14 +103,13 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) > min_not_zero(dev->coherent_dma_mask, dev->bus_dma_mask); > } > > -void *dma_direct_alloc_pages(struct device *dev, size_t size, > +struct page *__dma_direct_alloc_pages(struct device *dev, size_t size, > dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) > { > unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; > int page_order = get_order(size); > struct page *page = NULL; > u64 phys_mask; > - void *ret; > > if (attrs & DMA_ATTR_NO_WARN) > gfp |= __GFP_NOWARN; > @@ -150,11 +149,22 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, > } > } > > + return page; > +} > + > +void *dma_direct_alloc_pages(struct device *dev, size_t size, > + dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) > +{ > + struct page *page; > + void *ret; > + > + page = __dma_direct_alloc_pages(dev, size, dma_handle, gfp, attrs); > if (!page) > return NULL; > + > ret = page_address(page); > if (force_dma_unencrypted()) { > - set_memory_decrypted((unsigned long)ret, 1 << page_order); > + set_memory_decrypted((unsigned long)ret, 1 << get_order(size)); > *dma_handle = __phys_to_dma(dev, page_to_phys(page)); > } else { > *dma_handle = phys_to_dma(dev, page_to_phys(page)); > @@ -163,20 +173,22 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, > return ret; > } > > -/* > - * NOTE: this function must never look at the dma_addr argument, because we want > - * to be able to use it as a helper for iommu implementations as well. > - */ > +void __dma_direct_free_pages(struct device *dev, size_t size, struct page *page) > +{ > + unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; > + > + if (!dma_release_from_contiguous(dev, page, count)) > + __free_pages(page, get_order(size)); > +} > + > void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr, > dma_addr_t dma_addr, unsigned long attrs) > { > - unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; > unsigned int page_order = get_order(size); > > if (force_dma_unencrypted()) > set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order); > - if (!dma_release_from_contiguous(dev, virt_to_page(cpu_addr), count)) > - free_pages((unsigned long)cpu_addr, page_order); > + __dma_direct_free_pages(dev, size, virt_to_page(cpu_addr)); > } > > void *dma_direct_alloc(struct device *dev, size_t size, >
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