[PATCH v2] arm64/dma-mapping: fix DMA_ATTR_FORCE_CONTIGUOUS mmaping code

[Andrzej Hajda]

Hi,

Gently ping.

Regards
Andrzej

On 31.03.2017 13:02, Andrzej Hajda wrote:
> In case of DMA_ATTR_FORCE_CONTIGUOUS allocations vm_area->pages
> is invalid. __iommu_mmap_attrs and __iommu_get_sgtable should not
> use it and take advantage of contiguous nature of the allocation.
>
> Fixes: 44176bb ("arm64: Add support for DMA_ATTR_FORCE_CONTIGUOUS to IOMMU")
> Signed-off-by: Andrzej Hajda <a.hajda at samsung.com>
> ---
> Hi Robin, Geert,
>
> In this version of the patch I have replaced temporal pages and
> iommu_dma_mmap with remap_pfn_range or rather its simplified version
> vm_iomap_memory.
> Unfortunately I have not find nice helper for sgtable creation, so I
> left sg allocation inside _iommu_mmap_attrs.
>
> As the fixing of DMA_ATTR_FORCE_CONTIGUOUS related crashes has higher
> priority I have focused only on it in this patch.
>
> Regards
> Andrzej
> ---
>  arch/arm64/mm/dma-mapping.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index f7b5401..41c7c36 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -703,6 +703,10 @@ static int __iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
>  	if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
>  		return ret;
>  
> +	if (attrs & DMA_ATTR_FORCE_CONTIGUOUS)
> +		return vm_iomap_memory(vma,
> +				page_to_phys(vmalloc_to_page(cpu_addr)), size);
> +
>  	area = find_vm_area(cpu_addr);
>  	if (WARN_ON(!area || !area->pages))
>  		return -ENXIO;
> @@ -715,8 +719,19 @@ static int __iommu_get_sgtable(struct device *dev, struct sg_table *sgt,
>  			       size_t size, unsigned long attrs)
>  {
>  	unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> -	struct vm_struct *area = find_vm_area(cpu_addr);
> +	struct vm_struct *area;
> +
> +	if (attrs & DMA_ATTR_FORCE_CONTIGUOUS) {
> +		int ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
> +
> +		if (!ret)
> +			sg_set_page(sgt->sgl, vmalloc_to_page(cpu_addr),
> +				    PAGE_ALIGN(size), 0);
>  
> +		return ret;
> +	}
> +
> +	area = find_vm_area(cpu_addr);
>  	if (WARN_ON(!area || !area->pages))
>  		return -ENXIO;
>