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

* [PATCH v3 8/9] xen/gntdev.c: Convert to use vm_map_pages()
@ 2019-02-13 14:07 Souptick Joarder
  2019-02-14 15:59 ` kbuild test robot
  2019-02-14 16:55 ` kbuild test robot
  0 siblings, 2 replies; 3+ messages in thread
From: Souptick Joarder @ 2019-02-13 14:07 UTC (permalink / raw)
  To: akpm, willy, mhocko, boris.ostrovsky, jgross, linux, robin.murphy
  Cc: xen-devel, linux-kernel, linux-mm

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@gmail.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 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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