Hi Kees, Thanks for your patch. The switch statement is needed for multiple planes which is already approved in this patch series. https://patchwork.kernel.org/project/dri-devel/patch/20210728003126.1425028-13-anitha.chrisanthus@xxxxxxxxx/ This patch has dependencies on the previous patches in this series, and we are waiting for reviews on those before this can be checked in. Thanks, Anitha > -----Original Message----- > From: Kees Cook <keescook@xxxxxxxxxxxx> > Sent: Wednesday, August 25, 2021 11:18 AM > To: Chrisanthus, Anitha <anitha.chrisanthus@xxxxxxxxx> > Cc: Kees Cook <keescook@xxxxxxxxxxxx>; Dea, Edmund J > <edmund.j.dea@xxxxxxxxx>; David Airlie <airlied@xxxxxxxx>; Daniel Vetter > <daniel@xxxxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx; Sam Ravnborg > <sam@xxxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; linux- > hardening@xxxxxxxxxxxxxxx > Subject: [PATCH] drm/kmb: Avoid warnings on impossible plane_id > > 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@xxxxxxxxx> > Cc: Edmund Dea <edmund.j.dea@xxxxxxxxx> > Cc: David Airlie <airlied@xxxxxxxx> > Cc: Daniel Vetter <daniel@xxxxxxxx> > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx > Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display") > Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> > --- > 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; > } > > -- > 2.30.2
