Re: [PATCH v4 6/6] arm: dma-mapping: updates to limit dma_mask and iommu mapping size
From: Murali Karicheri
Date: Tue Jan 27 2015 - 10:20:32 EST
On 01/27/2015 06:34 AM, Catalin Marinas wrote:
On Tue, Jan 27, 2015 at 11:12:32AM +0000, Robin Murphy wrote:
On 23/01/15 22:32, Murali Karicheri wrote:
Limit the dma_mask to minimum of dma_mask and dma_base + size - 1.
Also arm_iommu_create_mapping() has size parameter of size_t and
arm_setup_iommu_dma_ops() can take a value higher than that. So
limit the size to SIZE_MAX.
Signed-off-by: Murali Karicheri<m-karicheri2@xxxxxx>
---
arch/arm/mm/dma-mapping.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 7864797..a1f9030 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -2004,6 +2004,13 @@ static bool arm_setup_iommu_dma_ops(struct device *dev, u64 dma_base, u64 size,
if (!iommu)
return false;
+ /*
+ * currently arm_iommu_create_mapping() takes a max of size_t
+ * for size param. So check this limit for now.
+ */
+ if (size> SIZE_MAX)
+ return false;
+
mapping = arm_iommu_create_mapping(dev->bus, dma_base, size);
if (IS_ERR(mapping)) {
pr_warn("Failed to create %llu-byte IOMMU mapping for device %s\n",
@@ -2053,6 +2060,9 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
{
struct dma_map_ops *dma_ops;
+ /* limit dma_mask to the lower of the two values */
+ *dev->dma_mask = min((*dev->dma_mask), (dma_base + size - 1));
+
Is there any reason not to do this in of_dma_configure? It seems like
something everyone could benefit from - I'd cooked up a dodgy workaround
for the same issue in my arm64 IOMMU code, but handling it generically
in common code would be much nicer.
Ok Will move this to of_dma_configure().
Murali
I agree. I started something here:
http://article.gmane.org/gmane.linux.kernel/1835096
but I don't remember to have got to a clear conclusion.
--
Murali Karicheri
Linux Kernel, Texas Instruments
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