[2/2] ARM: DMA: Use vm_pgoff for IOMMU mmap
diff mbox

Message ID 1429195312-25898-2-git-send-email-orjan.eide@arm.com
State New, archived
Headers show

Commit Message

Ørjan Eide April 16, 2015, 2:41 p.m. UTC
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@arm.com>
---
 arch/arm/mm/dma-mapping.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Comments

Daniel Kurtz April 20, 2015, 4:13 a.m. UTC | #1
Hi Ørjan,

On Thu, Apr 16, 2015 at 10:41 PM, Ørjan Eide <orjan.eide@arm.com> wrote:
> 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@arm.com>

Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>

I tested this patch on my RK3288 board with the corresponding
rockchip_drm patch [0], and it works.  So, also:
Tested-by: Daniel Kurtz <djkurtz@chromium.org>

[0] https://patchwork.kernel.org/patch/6226591/



> ---
>  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
>

Patch
diff mbox

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) {