mm/nommu.c: fix remap_pfn_range()

remap_pfn_range() means map physical address pfn<<PAGE_SHIFT to user addr.

For nommu arch it's implemented by vma->vm_start = pfn << PAGE_SHIFT which
is wrong acroding the original meaning of this function.  And some driver
developer using remap_pfn_range() with correct parameter will get
unexpected result because vm_start is changed.  It should be implementd
like addr = pfn << PAGE_SHIFT but which is meanless on nommu arch, this
patch just make it simply return.

Parameter name and setting of vma->vm_flags also be fixed.

Signed-off-by: Bob Liu <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: David Howells <[email protected]>
Acked-by: Greg Ungerer <[email protected]>
Cc: Mike Frysinger <[email protected]>
Cc: Bob Liu <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 6 insertions, 3 deletions

diff --git a/mm/nommu.c b/mm/nommu.c
index 1fd0c51b10a6..9edc897a3970 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1813,10 +1813,13 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
 	return NULL;
 }
 
-int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
-		unsigned long to, unsigned long size, pgprot_t prot)
+int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
+		unsigned long pfn, unsigned long size, pgprot_t prot)
 {
-	vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
+	if (addr != (pfn << PAGE_SHIFT))
+		return -EINVAL;
+
+	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
 	return 0;
 }
 EXPORT_SYMBOL(remap_pfn_range);