[PATCH 3/7] drm/udl: import prime-fds with proper page-alignment

[David Herrmann]

Instead of rounding down to the next lower page-boundary, round up.
dma-buf guarantees that we can map buffers in multiples of a page, so if
an exporter does not page-align, do it ourselves.

This avoids issues if the exported buffer contains an unaligned size and
we crop it. In this case, the buffer is too small for the UDL CRTC. So we
round up to page-size now and avoid black borders. Worst case is we end up
reading out some random kernel memory, but we can never fault as the whole
page has the same access-rights. And in this case it's an issue of the
buggy exporting driver, not the importing one.

Signed-off-by: David Herrmann <dh.herrmann at gmail.com>
---
 drivers/gpu/drm/udl/udl_gem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/udl/udl_gem.c b/drivers/gpu/drm/udl/udl_gem.c
index df963a1..1069e57 100644
--- a/drivers/gpu/drm/udl/udl_gem.c
+++ b/drivers/gpu/drm/udl/udl_gem.c
@@ -227,7 +227,7 @@ static int udl_prime_create(struct drm_device *dev,
 	struct udl_gem_object *obj;
 	int npages;
 
-	npages = size / PAGE_SIZE;
+	npages = PAGE_ALIGN(size) >> PAGE_SHIFT;
 
 	*obj_p = NULL;
 	obj = udl_gem_alloc_object(dev, npages * PAGE_SIZE);
-- 
1.8.5.3