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-rw-r--r--drivers/char/mem.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 42187381506..850a78c9c4b 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -261,7 +261,11 @@ static int mmap_mem(struct file * file, struct vm_area_struct * vma)
static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
{
- unsigned long long val;
+ unsigned long pfn;
+
+ /* Turn a kernel-virtual address into a physical page frame */
+ pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
+
/*
* RED-PEN: on some architectures there is more mapped memory
* than available in mem_map which pfn_valid checks
@@ -269,10 +273,10 @@ static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
*
* RED-PEN: vmalloc is not supported right now.
*/
- if (!pfn_valid(vma->vm_pgoff))
+ if (!pfn_valid(pfn))
return -EIO;
- val = (u64)vma->vm_pgoff << PAGE_SHIFT;
- vma->vm_pgoff = __pa(val) >> PAGE_SHIFT;
+
+ vma->vm_pgoff = pfn;
return mmap_mem(file, vma);
}