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authorAndrew G. Harvey <agh@cisco.com>2008-09-24 01:10:02 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2008-10-16 09:24:54 -0700
commit02683ffdf655b4ae15245376ba6fea6d9e5829a6 (patch)
tree9b66a97df10db3d09be94e90b90f1e3b6eaa4934 /drivers/uio/uio.c
parenta6030fcc608bd333c80eab3bfc72f63906476c61 (diff)
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>
Diffstat (limited to 'drivers/uio/uio.c')
-rw-r--r--drivers/uio/uio.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
index 557e73ef588..5dccf057a7d 100644
--- a/drivers/uio/uio.c
+++ b/drivers/uio/uio.c
@@ -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;