drm/i915: Declare i915_gem_object_create_internal() as taking phys_addr_t size

The internal object is a collection of struct pages and so is
intrinsically linked to the available physical memory on the machine,
and not an arbitrary type from the uabi. Use phys_addr_t so the link
between size and memory consumption is clear, and then double check that
we don't overflow the maximum object size.

v2: Also assert that size is not zero - a mistake I made a few times
while writing selftests.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170112130431.1844-1-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_internal.c b/drivers/gpu/drm/i915/i915_gem_internal.c
index 2222863e505f..9b39472396ef 100644
--- a/drivers/gpu/drm/i915/i915_gem_internal.c
+++ b/drivers/gpu/drm/i915/i915_gem_internal.c
@@ -151,10 +151,15 @@ static const struct drm_i915_gem_object_ops i915_gem_object_internal_ops = {
  */
 struct drm_i915_gem_object *
 i915_gem_object_create_internal(struct drm_i915_private *i915,
-				unsigned int size)
+				phys_addr_t size)
 {
 	struct drm_i915_gem_object *obj;
 
+	GEM_BUG_ON(!size);
+
+	if (overflows_type(size, obj->base.size))
+		return ERR_PTR(-E2BIG);
+
 	obj = i915_gem_object_alloc(i915);
 	if (!obj)
 		return ERR_PTR(-ENOMEM);