X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=mm%2Fnommu.c;h=53cab10fece40a3f5835604e62754818de0e1e7c;hb=a145d575833ff47330125364cb49304db7308825;hp=bf0cc762a7d203d6150114a2ec5b691bc739adff;hpb=e83c2b0ff325f52dda1aff3572d0e1516216c54b;p=pandora-kernel.git

diff --git a/mm/nommu.c b/mm/nommu.c
index bf0cc762a7d2..53cab10fece4 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -238,6 +238,27 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 }
 EXPORT_SYMBOL(get_user_pages);
 
+/**
+ * follow_pfn - look up PFN at a user virtual address
+ * @vma: memory mapping
+ * @address: user virtual address
+ * @pfn: location to store found PFN
+ *
+ * Only IO mappings and raw PFN mappings are allowed.
+ *
+ * Returns zero and the pfn at @pfn on success, -ve otherwise.
+ */
+int follow_pfn(struct vm_area_struct *vma, unsigned long address,
+	unsigned long *pfn)
+{
+	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
+		return -EINVAL;
+
+	*pfn = address >> PAGE_SHIFT;
+	return 0;
+}
+EXPORT_SYMBOL(follow_pfn);
+
 DEFINE_RWLOCK(vmlist_lock);
 struct vm_struct *vmlist;