On 12/03/2014 04:07 PM, Lars-Peter Clausen wrote:
> When running in non-cache coherent configuration the memory that was
> allocated with dma_alloc_coherent() has a custom mapping and so there is no
> 1-to-1 relationship between the kernel virtual address and the PFN. This
> means that virt_to_pfn() will not work correctly for those addresses and the
> default mmap implementation in the form of dma_common_mmap() will map some
> random, but not the requested, memory area.
>
> Fix this by providing a custom mmap implementation that looks up the PFN
> from the page table rather than using virt_to_pfn.
>
> Signed-off-by: Lars-Peter Clausen <l...@metafoo.de>
> ---
> arch/microblaze/include/asm/pgtable.h | 1 +
> arch/microblaze/kernel/dma.c | 26 ++++++++++++++++++++++++++
> arch/microblaze/mm/consistent.c | 23 ++++++++++++++++++-----
> 3 files changed, 45 insertions(+), 5 deletions(-)
>
> diff --git a/arch/microblaze/include/asm/pgtable.h
> b/arch/microblaze/include/asm/pgtable.h
> index 95cef0b..df19d0c 100644
> --- a/arch/microblaze/include/asm/pgtable.h
> +++ b/arch/microblaze/include/asm/pgtable.h
> @@ -565,6 +565,7 @@ void consistent_free(size_t size, void *vaddr);
> void consistent_sync(void *vaddr, size_t size, int direction);
> void consistent_sync_page(struct page *page, unsigned long offset,
> size_t size, int direction);
> +unsigned long consistent_virt_to_pfn(void *vaddr);
>
> void setup_memory(void);
> #endif /* __ASSEMBLY__ */
> diff --git a/arch/microblaze/kernel/dma.c b/arch/microblaze/kernel/dma.c
> index 4633c36..4822367 100644
> --- a/arch/microblaze/kernel/dma.c
> +++ b/arch/microblaze/kernel/dma.c
> @@ -154,9 +154,35 @@ dma_direct_sync_sg_for_device(struct device *dev,
> __dma_sync(sg->dma_address, sg->length, direction);
> }
>
> +int dma_direct_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
> + void *cpu_addr, dma_addr_t handle, size_t size,
> + struct dma_attrs *attrs)
> +{
> + unsigned long user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
> + unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> + unsigned long off = vma->vm_pgoff;
> + unsigned long pfn;
> +
> + if (!IS_ENABLED(CONFIG_MMU))
> + return -ENXIO;
> +
> + if (off >= count || user_count > (count - off))
> + return -ENXIO;
> +
> +#ifdef NOT_COHERENT_CACHE
> + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> + pfn = consistent_virt_to_pfn(cpu_addr);
> +#else
> + pfn = virt_to_pfn(cpu_addr);
> +#endif
> + return remap_pfn_range(vma, vma->vm_start, pfn + off,
> + vma->vm_end - vma->vm_start, vma->vm_page_prot);
> +}
> +
> struct dma_map_ops dma_direct_ops = {
> .alloc = dma_direct_alloc_coherent,
> .free = dma_direct_free_coherent,
> + .mmap = dma_direct_mmap_coherent,
> .map_sg = dma_direct_map_sg,
> .dma_supported = dma_direct_dma_supported,
> .map_page = dma_direct_map_page,
> diff --git a/arch/microblaze/mm/consistent.c b/arch/microblaze/mm/consistent.c
> index e10ad93..f358cd2 100644
> --- a/arch/microblaze/mm/consistent.c
> +++ b/arch/microblaze/mm/consistent.c
> @@ -156,6 +156,23 @@ void *consistent_alloc(gfp_t gfp, size_t size,
> dma_addr_t *dma_handle)
> }
> EXPORT_SYMBOL(consistent_alloc);
>
> +static pte_t *consistent_virt_to_pte(void *vaddr)
> +{
> + unsigned long addr = (unsigned long)vaddr;
> +
> + return pte_offset_kernel(pmd_offset(pgd_offset_k(addr), addr), addr);
> +}
> +
> +unsigned long consistent_virt_to_pfn(void *vaddr)
> +{
> + pte_t *ptep = consistent_virt_to_pte(vaddr);
> +
> + if (pte_none(*ptep) || !pte_present(*ptep))
> + return 0;
> +
> + return pte_pfn(*ptep);
> +}
> +
> /*
> * free page(s) as defined by the above mapping.
> */
> @@ -181,13 +198,9 @@ void consistent_free(size_t size, void *vaddr)
> } while (size -= PAGE_SIZE);
> #else
> do {
> - pte_t *ptep;
> + pte_t *ptep = consistent_virt_to_pte(vaddr);
> unsigned long pfn;
>
> - ptep = pte_offset_kernel(pmd_offset(pgd_offset_k(
> - (unsigned int)vaddr),
> - (unsigned int)vaddr),
> - (unsigned int)vaddr);
> if (!pte_none(*ptep) && pte_present(*ptep)) {
> pfn = pte_pfn(*ptep);
> pte_clear(&init_mm, (unsigned int)vaddr, ptep);
> Applied. Thanks, Michal -- Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91 w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/ Maintainer of Linux kernel - Xilinx Zynq ARM architecture Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform
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