diff options
Diffstat (limited to 'arch/arm/mm/dma-mapping.c')
| -rw-r--r-- | arch/arm/mm/dma-mapping.c | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 63eabb06f9f1..0268584f1fa0 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -935,13 +935,31 @@ static void arm_coherent_dma_free(struct device *dev, size_t size, void *cpu_add __arm_dma_free(dev, size, cpu_addr, handle, attrs, true); } +/* + * The whole dma_get_sgtable() idea is fundamentally unsafe - it seems + * that the intention is to allow exporting memory allocated via the + * coherent DMA APIs through the dma_buf API, which only accepts a + * scattertable. This presents a couple of problems: + * 1. Not all memory allocated via the coherent DMA APIs is backed by + * a struct page + * 2. Passing coherent DMA memory into the streaming APIs is not allowed + * as we will try to flush the memory through a different alias to that + * actually being used (and the flushes are redundant.) + */ int arm_dma_get_sgtable(struct device *dev, struct sg_table *sgt, void *cpu_addr, dma_addr_t handle, size_t size, unsigned long attrs) { - struct page *page = pfn_to_page(dma_to_pfn(dev, handle)); + unsigned long pfn = dma_to_pfn(dev, handle); + struct page *page; int ret; + /* If the PFN is not valid, we do not have a struct page */ + if (!pfn_valid(pfn)) + return -ENXIO; + + page = pfn_to_page(pfn); + ret = sg_alloc_table(sgt, 1, GFP_KERNEL); if (unlikely(ret)) return ret; @@ -2396,6 +2414,13 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size, dma_ops = arm_get_dma_map_ops(coherent); set_dma_ops(dev, dma_ops); + +#ifdef CONFIG_XEN + if (xen_initial_domain()) { + dev->archdata.dev_dma_ops = dev->dma_ops; + dev->dma_ops = xen_dma_ops; + } +#endif } void arch_teardown_dma_ops(struct device *dev) |