mm/nommu.c: fix remap_pfn_range()

commit 8f3b1327aa454bc8283e96bca7669c3c88b83f79 upstream.

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 <lliubbo@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Greg Ungerer <gerg@uclinux.org>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Bob Liu <lliubbo@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/mm/nommu.c b/mm/nommu.c
index c4c542c736a962774f0770eef0d50c419b19a2cb..0376a4c3387cf70b2435a5424fdbfb3f8bed9d7a 100644 (file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1819,10 +1819,13 @@ 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);