[Linaro-mm-sig] [PATCH 3/3] [RFC] Kernel Virtual Memory allocation issue in dma-mapping framework

[Abhinav Kochhar <kochhar.abhinav@gmail.com>]

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With this we can do a run time check on the allocation type for either
kernel or user using the dma attribute passed to dma-mapping iommu ops.

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c

index 2d11aa0..1f454cc 100644

--- a/arch/arm/mm/dma-mapping.c

+++ b/arch/arm/mm/dma-mapping.c

@@ -428,6 +428,7 @@ static void __dma_free_remap(void *cpu_addr, size_t
size)

        arm_vmregion_free(&consistent_head, c);

 }

+

 #else  /* !CONFIG_MMU */

 #define __dma_alloc_remap(page, size, gfp, prot, c)    page_address(page)

@@ -894,6 +895,35 @@ __iommu_alloc_remap(struct page **pages, size_t size,
gfp_t gfp, pgprot_t prot)

        size_t align;

        size_t count = size >> PAGE_SHIFT;

        int bit;

+        unsigned long mem_type = (unsigned long)gfp;

+

+

+       if(mem_type){

+

+               struct page_infodma *pages_in;

+

+               pages_in = kzalloc( sizeof(struct page_infodma*),
GFP_KERNEL);

+               if(!pages_in)

+                        return NULL;

+

+               pages_in->nr_pages = count;

+

+               return (void*)pages_in;

+

+       }

+

+       /*

+         * Align the virtual region allocation - maximum alignment is

+         * a section size, minimum is a page size.  This helps reduce

+         * fragmentation of the DMA space, and also prevents allocations

+         * smaller than a section from crossing a section boundary.

+         */

+

+        bit = fls(size - 1);

+        if (bit > SECTION_SHIFT)

+                bit = SECTION_SHIFT;

+        align = 1 << bit;

+

        if (!consistent_pte[0]) {

                pr_err("%s: not initialised\n", __func__);

@@ -901,16 +931,6 @@ __iommu_alloc_remap(struct page **pages, size_t size,
gfp_t gfp, pgprot_t prot)

                return NULL;

        }

-       /*

-        * Align the virtual region allocation - maximum alignment is

-        * a section size, minimum is a page size.  This helps reduce

-        * fragmentation of the DMA space, and also prevents allocations

-        * smaller than a section from crossing a section boundary.

-        */

-       bit = fls(size - 1);

-       if (bit > SECTION_SHIFT)

-               bit = SECTION_SHIFT;

-       align = 1 << bit;

        /*

         * Allocate a virtual address in the consistent mapping region.

@@ -946,6 +966,7 @@ __iommu_alloc_remap(struct page **pages, size_t size,
gfp_t gfp, pgprot_t prot)

        return NULL;

 }

+

 /*

  * Create a mapping in device IO address space for specified pages

  */

@@ -973,13 +994,16 @@ __iommu_create_mapping(struct device *dev, struct
page **pages, size_t size)

                len = (j - i) << PAGE_SHIFT;

                ret = iommu_map(mapping->domain, iova, phys, len, 0);

+

                if (ret < 0)

                        goto fail;

+

                iova += len;

                i = j;

        }

        return dma_addr;

 fail:

+

        iommu_unmap(mapping->domain, dma_addr, iova-dma_addr);

        __free_iova(mapping, dma_addr, size);

        return DMA_ERROR_CODE;

@@ -1007,6 +1031,8 @@ static void *arm_iommu_alloc_attrs(struct device
*dev, size_t size,

        pgprot_t prot = __get_dma_pgprot(attrs, pgprot_kernel);

        struct page **pages;

        void *addr = NULL;

+       struct page_infodma *page_ret;

+       unsigned long mem_type;

        *handle = DMA_ERROR_CODE;

        size = PAGE_ALIGN(size);

@@ -1019,11 +1045,19 @@ static void *arm_iommu_alloc_attrs(struct device
*dev, size_t size,

        if (*handle == DMA_ERROR_CODE)

                goto err_buffer;

-       addr = __iommu_alloc_remap(pages, size, gfp, prot);

+       mem_type = dma_get_attr(DMA_ATTR_USER_SPACE, attrs);

+

+       addr = __iommu_alloc_remap(pages, size, mem_type, prot);

        if (!addr)

                goto err_mapping;

-       return addr;

+       if(mem_type){

+               page_ret = (struct page_infodma *)addr;

+               page_ret->pages = pages;

+               return page_ret;

+       }

+       else

+               return addr;

 err_mapping:

        __iommu_remove_mapping(dev, *handle, size);

@@ -1071,18 +1105,34 @@ static int arm_iommu_mmap_attrs(struct device *dev,
struct vm_area_struct *vma,

 void arm_iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,

                          dma_addr_t handle, struct dma_attrs *attrs)

 {

-       struct arm_vmregion *c;

+

+       unsigned long mem_type = dma_get_attr(DMA_ATTR_USER_SPACE, attrs);

+

        size = PAGE_ALIGN(size);

-       c = arm_vmregion_find(&consistent_head, (unsigned long)cpu_addr);

-       if (c) {

-               struct page **pages = c->priv;

-               __dma_free_remap(cpu_addr, size);

-               __iommu_remove_mapping(dev, handle, size);

-               __iommu_free_buffer(dev, pages, size);

+

+       if(mem_type){

+

+               struct page_infodma *pagesin = cpu_addr;

+               if (pagesin) {

+                       struct page **pages = pagesin->pages;

+                       __iommu_remove_mapping(dev, handle, size);

+                       __iommu_free_buffer(dev, pages, size);

+                }

+       }

+       else{

+               struct arm_vmregion *c;

+               c = arm_vmregion_find(&consistent_head, (unsigned
long)cpu_addr);

+               if (c) {

+                       struct page **pages = c->priv;

+                       __dma_free_remap(cpu_addr, size);

+                       __iommu_remove_mapping(dev, handle, size);

+                       __iommu_free_buffer(dev, pages, size);

+               }

        }

 }

+

 /*

  * Map a part of the scatter-gather list into contiguous io address space

  */

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