Hello,
On Monday, December 06, 2010 11:53 AM Marek Szyprowski wrote:
> From: Pawel Osciak <p.osciak@xxxxxxxxxxx>
>
> Add generic memory handling routines for userspace pointer handling,
> contiguous memory verification and mapping.
>
> Signed-off-by: Pawel Osciak <p.osciak@xxxxxxxxxxx>
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> CC: Pawel Osciak <pawel@xxxxxxxxxx>
> ---
> drivers/media/video/Kconfig | 3 +
> drivers/media/video/Makefile | 1 +
> drivers/media/video/videobuf2-memops.c | 232 ++++++++++++++++++++++++++++++++
> include/media/videobuf2-memops.h | 44 ++++++
> 4 files changed, 280 insertions(+), 0 deletions(-)
> create mode 100644 drivers/media/video/videobuf2-memops.c
> create mode 100644 include/media/videobuf2-memops.h
>
> diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
> index fef6a14..83ce858 100644
> --- a/drivers/media/video/Kconfig
> +++ b/drivers/media/video/Kconfig
> @@ -52,6 +52,9 @@ config V4L2_MEM2MEM_DEV
> config VIDEOBUF2_CORE
> tristate
>
> +config VIDEOBUF2_MEMOPS
> + tristate
> +
> #
> # Multimedia Video device configuration
> #
> diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
> index 77c4f85..a97a2a0 100644
> --- a/drivers/media/video/Makefile
> +++ b/drivers/media/video/Makefile
> @@ -115,6 +115,7 @@ obj-$(CONFIG_VIDEOBUF_DVB) += videobuf-dvb.o
> obj-$(CONFIG_VIDEO_BTCX) += btcx-risc.o
>
> obj-$(CONFIG_VIDEOBUF2_CORE) += videobuf2-core.o
> +obj-$(CONFIG_VIDEOBUF2_MEMOPS) += videobuf2-memops.o
>
> obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
>
> diff --git a/drivers/media/video/videobuf2-memops.c b/drivers/media/video/videobuf2-memops.c
> new file mode 100644
> index 0000000..69aa6dc
> --- /dev/null
> +++ b/drivers/media/video/videobuf2-memops.c
> @@ -0,0 +1,232 @@
> +/*
> + * videobuf2-memops.c - generic memory handling routines for videobuf2
> + *
> + * Copyright (C) 2010 Samsung Electronics
> + *
> + * Author: Pawel Osciak <p.osciak@xxxxxxxxxxx>
> + * Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/vmalloc.h>
> +#include <linux/cma.h>
> +#include <linux/mm.h>
> +#include <linux/sched.h>
> +#include <linux/file.h>
> +#include <linux/slab.h>
> +
> +#include <media/videobuf2-core.h>
> +#include <media/videobuf2-memops.h>
> +
> +/**
> + * vb2_get_vma() - acquire and lock the memory area
> + * @vaddr: virtual userspace address to the given area
> + *
> + * This function attempts to acquire an area mapped in the userspace for
> + * the duration of a hardware operation.
> + *
> + * Returns a virtual memory region associated with the given vaddr on success
> + * or NULL.
> + */
> +struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma)
> +{
> + struct vm_area_struct *vma_copy;
> +
> + vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL);
> + if (vma_copy == NULL)
> + return NULL;
> +
> + if (vma->vm_ops && vma->vm_ops->open)
> + vma->vm_ops->open(vma);
> +
> + if (vma->vm_file)
> + get_file(vma->vm_file);
> +
> + memcpy(vma_copy, vma, sizeof(*vma));
> +
> + vma_copy->vm_mm = NULL;
> + vma_copy->vm_next = NULL;
> + vma_copy->vm_prev = NULL;
> +
> + return vma_copy;
> +}
> +
> +/**
> + * vb2_put_userptr() - release a userspace memory area
> + * @vma: virtual memory region associated with the area to be released
> + *
> + * This function releases the previously acquired memory area after a hardware
> + * operation.
> + */
> +void vb2_put_vma(struct vm_area_struct *vma)
> +{
> + if (!vma)
> + return;
> +
> + if (vma->vm_file)
> + fput(vma->vm_file);
> +
> + if (vma->vm_ops && vma->vm_ops->close)
> + vma->vm_ops->close(vma);
> +
> + kfree(vma);
> +}
> +
> +/**
> + * vb2_contig_verify_userptr() - verify contiguity of a userspace-mapped memory
> + * @vma: virtual memory region which maps the physical memory
> + * to be verified
> + * @vaddr: starting virtual address of the area to be verified
> + * @size: size of the area to be verified
> + * @paddr: will return physical address for the given vaddr
> + *
> + * This function will go through memory area of size size mapped at vaddr and
> + * verify that the underlying physical pages are contiguous.
> + *
> + * Returns 0 on success and a physical address to the memory pointed
> + * to by vaddr in paddr.
> + */
> +int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
> + struct vm_area_struct **res_vma, dma_addr_t *res_pa)
> +{
> + struct mm_struct *mm = current->mm;
> + struct vm_area_struct *vma;
> + unsigned long offset, start, end;
> + unsigned long this_pfn, prev_pfn;
> + dma_addr_t pa = 0;
> + int ret = -EFAULT;
> +
> + start = vaddr;
> + offset = start & ~PAGE_MASK;
> + end = start + size;
> +
> + down_read(&mm->mmap_sem);
> + vma = find_vma(mm, start);
> +
> + if (vma == NULL || vma->vm_end < end)
> + goto done;
> +
> + for (prev_pfn = 0; start <= end; start += PAGE_SIZE) {
I did an ugly off-by-one bug here. "start < end" comparison should be used instead.
> + ret = follow_pfn(vma, start, &this_pfn);
> + if (ret)
> + goto done;
> +
> + if (prev_pfn == 0)
> + pa = this_pfn << PAGE_SHIFT;
> + else if (this_pfn != prev_pfn + 1) {
> + ret = -EFAULT;
> + goto done;
> + }
> + prev_pfn = this_pfn;
> + }
> +
> + /*
> + * Memory is contigous, lock vma and return to the caller
> + */
> + *res_vma = vb2_get_vma(vma);
> + if (*res_vma == NULL) {
> + ret = -ENOMEM;
> + goto done;
> + }
> + *res_pa = pa + offset;
> + ret = 0;
> +
> +done:
> + up_read(&mm->mmap_sem);
> + return ret;
> +}
> +
<snip>
Best regards
--
Marek Szyprowski
Samsung Poland R&D Center
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