[Intel-gfx] [PATCH 18/23] drm/i915: Shrink the size of intel_remapped_plane_info struct

[Imre Deak]

Save some place in the GTT VMAs by using a u16 instead of unsigned int
to store the view dimensions. The maximum FB stride is 256kB which is
4096 tiles in the worst case (yf-tiles), the maximum FB height is 16k
pixels, which is 2048 tiles in the worst case (x-tiles).

Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/display/intel_fb.c | 15 ++++++++++++---
 drivers/gpu/drm/i915/i915_vma_types.h   | 12 ++++++++----
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fb.c b/drivers/gpu/drm/i915/display/intel_fb.c
index 16a1b5c922bb..51c56f0a4a99 100644
--- a/drivers/gpu/drm/i915/display/intel_fb.c
+++ b/drivers/gpu/drm/i915/display/intel_fb.c
@@ -619,13 +619,22 @@ static u32 calc_plane_remap_info(const struct intel_framebuffer *fb, int color_p
 	unsigned int tile_width = dims->tile_width;
 	unsigned int tile_height = dims->tile_height;
 	unsigned int tile_size = intel_tile_size(i915);
+	unsigned int stride_tiles = plane_view_stride_tiles(fb, color_plane, dims);
+	unsigned int width_tiles = DIV_ROUND_UP(x + dims->width, dims->tile_width);
+	unsigned int height_tiles = plane_view_tile_rows(fb, color_plane, dims, y);
 	unsigned int pitch_tiles;
 	struct drm_rect r;
 
+	drm_WARN_ON(&i915->drm,
+		    overflows_type(obj_offset, gtt_remap_info->offset) ||
+		    overflows_type(stride_tiles, gtt_remap_info->stride) ||
+		    overflows_type(width_tiles, gtt_remap_info->width) ||
+		    overflows_type(height_tiles, gtt_remap_info->height));
+
 	gtt_remap_info->offset = obj_offset;
-	gtt_remap_info->width = DIV_ROUND_UP(x + dims->width, dims->tile_width);
-	gtt_remap_info->height = plane_view_tile_rows(fb, color_plane, dims, y);
-	gtt_remap_info->stride = plane_view_stride_tiles(fb, color_plane, dims);
+	gtt_remap_info->stride = stride_tiles;
+	gtt_remap_info->width = width_tiles;
+	gtt_remap_info->height = height_tiles;
 
 	if (view_type == I915_GGTT_VIEW_ROTATED) {
 		/* rotate the x/y offsets to match the GTT view */
diff --git a/drivers/gpu/drm/i915/i915_vma_types.h b/drivers/gpu/drm/i915/i915_vma_types.h
index f5cb848b7a7e..358b4306fc00 100644
--- a/drivers/gpu/drm/i915/i915_vma_types.h
+++ b/drivers/gpu/drm/i915/i915_vma_types.h
@@ -97,12 +97,16 @@ enum i915_cache_level;
 
 struct intel_remapped_plane_info {
 	/* in gtt pages */
-	unsigned int width, height, stride, offset;
+	u32 offset;
+	u16 width;
+	u16 height;
+	u16 stride;
+	u16 unused_mbz;
 } __packed;
 
 struct intel_remapped_info {
 	struct intel_remapped_plane_info plane[2];
-	unsigned int unused_mbz;
+	u32 unused_mbz;
 } __packed;
 
 struct intel_rotation_info {
@@ -123,9 +127,9 @@ enum i915_ggtt_view_type {
 
 static inline void assert_i915_gem_gtt_types(void)
 {
-	BUILD_BUG_ON(sizeof(struct intel_rotation_info) != 8*sizeof(unsigned int));
+	BUILD_BUG_ON(sizeof(struct intel_rotation_info) != 2 * sizeof(u32) + 8 * sizeof(u16));
 	BUILD_BUG_ON(sizeof(struct intel_partial_info) != sizeof(u64) + sizeof(unsigned int));
-	BUILD_BUG_ON(sizeof(struct intel_remapped_info) != 9*sizeof(unsigned int));
+	BUILD_BUG_ON(sizeof(struct intel_remapped_info) != 3 * sizeof(u32) + 8 * sizeof(u16));
 
 	/* Check that rotation/remapped shares offsets for simplicity */
 	BUILD_BUG_ON(offsetof(struct intel_remapped_info, plane[0]) !=
-- 
2.25.1