KMB_MAX_PLANES is defined as 1, yet kmb_plane_atomic_disable() had code for writing beyond 1. It is gated by a WARN_ON() that would skip it, though, but under some compiler versions, poor Dead Code Elimination wasn't optimizing away the unused switch cases, leading to array bounds warnings when building with -Warray-bounds:
drivers/gpu/drm/kmb/kmb_plane.c:135:20: warning: array subscript 3 is above array bounds of 'struct layer_status[1]' [-Warray-bounds] drivers/gpu/drm/kmb/kmb_plane.c:132:20: warning: array subscript 2 is above array bounds of 'struct layer_status[1]' [-Warray-bounds] drivers/gpu/drm/kmb/kmb_plane.c:129:20: warning: array subscript 1 is above array bounds of 'struct layer_status[1]' [-Warray-bounds]
Instead, just remove the switch statement entirely and adjust the index type to match the struct "id" member.
Cc: Anitha Chrisanthus anitha.chrisanthus@intel.com Cc: Edmund Dea edmund.j.dea@intel.com Cc: David Airlie airlied@linux.ie Cc: Daniel Vetter daniel@ffwll.ch Cc: dri-devel@lists.freedesktop.org Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display") Signed-off-by: Kees Cook keescook@chromium.org --- drivers/gpu/drm/kmb/kmb_plane.c | 18 ++---------------- 1 file changed, 2 insertions(+), 16 deletions(-)
diff --git a/drivers/gpu/drm/kmb/kmb_plane.c b/drivers/gpu/drm/kmb/kmb_plane.c index ecee6782612d..3d46e756f2fe 100644 --- a/drivers/gpu/drm/kmb/kmb_plane.c +++ b/drivers/gpu/drm/kmb/kmb_plane.c @@ -113,7 +113,7 @@ static void kmb_plane_atomic_disable(struct drm_plane *plane, struct drm_atomic_state *state) { struct kmb_plane *kmb_plane = to_kmb_plane(plane); - int plane_id = kmb_plane->id; + unsigned char plane_id = kmb_plane->id; struct kmb_drm_private *kmb;
kmb = to_kmb(plane->dev); @@ -121,21 +121,7 @@ static void kmb_plane_atomic_disable(struct drm_plane *plane, if (WARN_ON(plane_id >= KMB_MAX_PLANES)) return;
- switch (plane_id) { - case LAYER_0: - kmb->plane_status[plane_id].ctrl = LCD_CTRL_VL1_ENABLE; - break; - case LAYER_1: - kmb->plane_status[plane_id].ctrl = LCD_CTRL_VL2_ENABLE; - break; - case LAYER_2: - kmb->plane_status[plane_id].ctrl = LCD_CTRL_GL1_ENABLE; - break; - case LAYER_3: - kmb->plane_status[plane_id].ctrl = LCD_CTRL_GL2_ENABLE; - break; - } - + kmb->plane_status[plane_id].ctrl = LCD_CTRL_VL1_ENABLE; kmb->plane_status[plane_id].disable = true; }