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UIO: Fix mapping of logical and virtual memory 

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>
This commit is contained in:
Andrew G. Harvey 2008-09-24 01:10:02 +02:00 committed by Greg Kroah-Hartman
parent a6030fcc60
commit 02683ffdf6
1 changed files with 10 additions and 2 deletions
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12
drivers/uio/uio.c
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@ -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;