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 <[email protected]>
Cc: Edmund Dea <[email protected]>
Cc: David Airlie <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: [email protected]
Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display")
Signed-off-by: Kees Cook <[email protected]>
---
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
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/[email protected]/
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 <[email protected]>
> Sent: Wednesday, August 25, 2021 11:18 AM
> To: Chrisanthus, Anitha <[email protected]>
> Cc: Kees Cook <[email protected]>; Dea, Edmund J
> <[email protected]>; David Airlie <[email protected]>; Daniel Vetter
> <[email protected]>; [email protected]; Sam Ravnborg
> <[email protected]>; [email protected]; linux-
> [email protected]
> 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 <[email protected]>
> Cc: Edmund Dea <[email protected]>
> Cc: David Airlie <[email protected]>
> Cc: Daniel Vetter <[email protected]>
> Cc: [email protected]
> Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display")
> Signed-off-by: Kees Cook <[email protected]>
> ---
> 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
Hi Kees,
This patch https://patchwork.kernel.org/project/dri-devel/patch/[email protected]/ is pushed to drm-misc-fixes. This change should fix the below warnings.
I apologize for all the inconveniences.
Thanks,
Anitha
> -----Original Message-----
> From: Chrisanthus, Anitha
> Sent: Wednesday, August 25, 2021 1:44 PM
> To: Kees Cook <[email protected]>
> Cc: Dea, Edmund J <[email protected]>; David Airlie <[email protected]>;
> Daniel Vetter <[email protected]>; [email protected]; Sam
> Ravnborg <[email protected]>; [email protected]; linux-
> [email protected]
> Subject: RE: [PATCH] drm/kmb: Avoid warnings on impossible plane_id
>
> 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/[email protected]/
>
> 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 <[email protected]>
> > Sent: Wednesday, August 25, 2021 11:18 AM
> > To: Chrisanthus, Anitha <[email protected]>
> > Cc: Kees Cook <[email protected]>; Dea, Edmund J
> > <[email protected]>; David Airlie <[email protected]>; Daniel Vetter
> > <[email protected]>; [email protected]; Sam Ravnborg
> > <[email protected]>; [email protected]; linux-
> > [email protected]
> > 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 <[email protected]>
> > Cc: Edmund Dea <[email protected]>
> > Cc: David Airlie <[email protected]>
> > Cc: Daniel Vetter <[email protected]>
> > Cc: [email protected]
> > Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display")
> > Signed-off-by: Kees Cook <[email protected]>
> > ---
> > 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
On Tue, Sep 07, 2021 at 05:32:53PM +0000, Chrisanthus, Anitha wrote:
> Hi Kees,
> This patch https://patchwork.kernel.org/project/dri-devel/patch/[email protected]/ is pushed to drm-misc-fixes. This change should fix the below warnings.
>
> I apologize for all the inconveniences.
No worries; thanks for the heads-up!
(sfr, this change should fix the warning[1] uncovered by the KSPP tree now.)
-Kees
[1] https://lore.kernel.org/linux-next/[email protected]/
--
Kees Cook