[Xen-devel] [PATCH v3 8/9] xen/gntdev.c: Convert to use vm_map_pages()

[Souptick Joarder <jrdr.linux@xxxxxxxxx>]

Convert to use vm_map_pages() to map range of kernel
memory to user vma.

map->count is passed to vm_map_pages() and internal API
verify map->count against count ( count = vma_pages(vma))
for page array boundary overrun. With this count is not
needed inside gntdev_mmap() and it could be replaced with
vma_pages(vma).

Signed-off-by: Souptick Joarder <jrdr.linux@xxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 drivers/xen/gntdev.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 5efc5ee..7f65ba3 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -1082,18 +1082,17 @@ static int gntdev_mmap(struct file *flip, struct 
vm_area_struct *vma)
 {
        struct gntdev_priv *priv = flip->private_data;
        int index = vma->vm_pgoff;
-       int count = vma_pages(vma);
        struct gntdev_grant_map *map;
-       int i, err = -EINVAL;
+       int err = -EINVAL;
 
        if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
                return -EINVAL;
 
        pr_debug("map %d+%d at %lx (pgoff %lx)\n",
-                       index, count, vma->vm_start, vma->vm_pgoff);
+                       index, vma_pages(vma), vma->vm_start, vma->vm_pgoff);
 
        mutex_lock(&priv->lock);
-       map = gntdev_find_map_index(priv, index, count);
+       map = gntdev_find_map_index(priv, index, vma_pages(vma));
        if (!map)
                goto unlock_out;
        if (use_ptemod && map->vma)
@@ -1145,12 +1144,9 @@ static int gntdev_mmap(struct file *flip, struct 
vm_area_struct *vma)
                goto out_put_map;
 
        if (!use_ptemod) {
-               for (i = 0; i < count; i++) {
-                       err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
-                               map->pages[i]);
-                       if (err)
-                               goto out_put_map;
-               }
+               err = vm_map_pages(vma, map->pages, map->count);
+               if (err)
+                       goto out_put_map;
        } else {
 #ifdef CONFIG_X86
                /*
-- 
1.9.1


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