UIO: Fix mapping of logical and virtual memory (02683ffd) · Commits · 戴 / test

mmap() doesn't work as expected for UIO_MEM_LOGICAL or UIO_MEM_VIRTUAL mappings. The offset into the memory needs to be added, otherwise uio_vma_fault always returns the first page only. Note that for UIO userspace calls mmap() with offset = N * getpagesize() to access mapping N. This must be compensated when calculating the offset. A comment was added to explain this since it is not obvious. Signed-off-by:

Andrew G. Harvey <agh@cisco.com> Signed-off-by:

Hans J. Koch <hjk@linutronix.de> Signed-off-by:

Greg Kroah-Hartman <gregkh@suse.de>

drivers/uio/uio.c

+10 −2

Original line number	Diff line number	Diff line
		@@ -490,15 +490,23 @@ static int uio_vma_fault(struct vm_area_struct vma, struct vm_fault vmf)
		{
		struct uio_device *idev = vma->vm_private_data;
		struct page *page;
		unsigned long offset;

		int mi = uio_find_mem_index(vma);
		if (mi < 0)
		return VM_FAULT_SIGBUS;

		/*
		* We need to subtract mi because userspace uses offset = N*PAGE_SIZE
		* to use mem[N].
		*/
		offset = (vmf->pgoff - mi) << PAGE_SHIFT;

		if (idev->info->mem[mi].memtype == UIO_MEM_LOGICAL)
		page = virt_to_page(idev->info->mem[mi].addr);
		page = virt_to_page(idev->info->mem[mi].addr + offset);
		else
		page = vmalloc_to_page((void*)idev->info->mem[mi].addr);
		page = vmalloc_to_page((void *)idev->info->mem[mi].addr
		+ offset);
		get_page(page);
		vmf->page = page;
		return 0;

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