[PATCH v3 2/7] drm/i915: Mark the ggtt_view structs as packed

Chris Wilson
2017-01-13T10:33:20Z

In the next few patches, we will depend upon there being no
uninitialised bits inside the ggtt_view. To ensure this we add the
__packed attribute and double check with a build bug that gcc hasn't
expanded the struct to include some padding bytes.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
drivers/gpu/drm/i915/i915_gem_gtt.h | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 5dd3755a5a45..57cbd532dae1 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -156,12 +156,22 @@ struct intel_rotation_info {
/* tiles */
unsigned int width, height, stride, offset;
} plane[2];
-};
+} __packed;
+
+static inline void assert_intel_rotation_info_is_packed(void)
+{
+ BUILD_BUG_ON(sizeof(struct intel_rotation_info) != 8*sizeof(unsigned int));
+}

struct intel_partial_info {
u64 offset;
unsigned int size;
-};
+} __packed;
+
+static inline void assert_intel_partial_info_is_packed(void)
+{
+ BUILD_BUG_ON(sizeof(struct intel_partial_info) != sizeof(u64) + sizeof(unsigned int));
+}

struct i915_ggtt_view {
enum i915_ggtt_view_type type;
--
2.11.0