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Date: Thu, 16 Apr 2015 16:41:52 +0200 From: Ørjan Eide <orjan.eide@....com> To: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, linux-rockchip@...ts.infradead.org Cc: djkurtz@...omium.org Subject: [PATCH 2/2] ARM: DMA: Use vm_pgoff for IOMMU mmap arm_iommu_mmap_attrs() ignores the page offset in vma->vm_pgoff that was specified in the mmap call. Any user of dma_mmap_* will get an unexpected result when the device uses the IOMMU DMA ops. Some DRM driver that use dma_mmap_* seems to depend on it ignoring vma->vm_pgoff. Both the Samsung Exynos DRM driver before v3.18, and the current Rockchip DRM driver, use the page offset to pass GEM cookies that are used to look up the GEM buffers and then call dma_mmap_attrs() with the cookie value still in vma->vm_pgoff. rockchip_gem_mmap_buf() in drivers/gpu/drm/rockchip/rockchip_drm_gem.c still does this. It should be fixed before fixing arm_iommu_mmap_attrs(). Signed-off-by: Ørjan Eide <orjan.eide@....com> --- arch/arm/mm/dma-mapping.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index c274476..07d571b 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -1364,6 +1364,9 @@ static int arm_iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma, { unsigned long uaddr = vma->vm_start; unsigned long usize = vma->vm_end - vma->vm_start; + unsigned long nr_vma_pages = usize >> PAGE_SHIFT; + unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT; + unsigned long off = vma->vm_pgoff; struct page **pages = __iommu_get_pages(cpu_addr, attrs); vma->vm_page_prot = __get_dma_pgprot(attrs, vma->vm_page_prot); @@ -1371,6 +1374,11 @@ static int arm_iommu_mmap_attrs(struct device *dev, struct vm_area_struct *vma, if (!pages) return -ENXIO; + if (off >= nr_pages || nr_vma_pages > (nr_pages - off)) + return -ENXIO; + + pages += off; + do { int ret = vm_insert_page(vma, uaddr, *pages++); if (ret) { -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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