2 files changed, 47 insertions, 0 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 77a76101dcd9..903f3b71f4a7 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1124,6 +1124,8 @@ unsigned long vmalloc_to_pfn(void *addr);
 int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
                         unsigned long pfn, unsigned long size, pgprot_t);
 int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
+int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
+                        unsigned long pfn);
 
 struct page *follow_page(struct vm_area_struct *, unsigned long address,
                         unsigned int foll_flags);
diff --git a/mm/memory.c b/mm/memory.c
index 072c1135ad37..8b8f0d2b453d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1277,6 +1277,51 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *
 }
 EXPORT_SYMBOL(vm_insert_page);
 
+/**
+ * vm_insert_pfn - insert single pfn into user vma
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @pfn: source kernel pfn
+ *
+ * Similar to vm_inert_page, this allows drivers to insert individual pages
+ * they've allocated into a user vma. Same comments apply.
+ *
+ * This function should only be called from a vm_ops->fault handler, and
+ * in that case the handler should return NULL.
+ */
+int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
+                unsigned long pfn)
+{
+        struct mm_struct *mm = vma->vm_mm;
+        int retval;
+        pte_t *pte, entry;
+        spinlock_t *ptl;
+
+        BUG_ON(!(vma->vm_flags & VM_PFNMAP));
+        BUG_ON(is_cow_mapping(vma->vm_flags));
+
+        retval = -ENOMEM;
+        pte = get_locked_pte(mm, addr, &ptl);
+        if (!pte)
+                goto out;
+        retval = -EBUSY;
+        if (!pte_none(*pte))
+                goto out_unlock;
+
+        /* Ok, finally just insert the thing.. */
+        entry = pfn_pte(pfn, vma->vm_page_prot);
+        set_pte_at(mm, addr, pte, entry);
+        update_mmu_cache(vma, addr, entry);
+
+        retval = 0;
+out_unlock:
+        pte_unmap_unlock(pte, ptl);
+
+out:
+        return retval;
+}
+EXPORT_SYMBOL(vm_insert_pfn);
+
 /*
  * maps a range of physical memory into the requested pages. the old
  * mappings are removed. any references to nonexistent pages results