[PATCH v2 3/7] drm/msm: Use drm_mode_init() for on-stack modes

[PATCH v2 3/7] drm/msm: Use drm_mode_init() for on-stack modes

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Initialize on-stack modes with drm_mode_init() to guarantee
no stack garbage in the list head, or that we aren't copying
over another mode's list head.

Based on the following cocci script, with manual fixups:
@decl@
identifier M;
expression E;
@@
- struct drm_display_mode M = E;
+ struct drm_display_mode M;

@@
identifier decl.M;
expression decl.E;
statement S, S1;
@@
struct drm_display_mode M;
... when != S
+ drm_mode_init(&M, &E);
+
S1

@@
expression decl.E;
@@
- &*E
+ E

Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
index 2c14646661b7..0f71e8fe7be7 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
@@ -237,12 +237,13 @@ static void dpu_encoder_phys_vid_setup_timing_engine(
 	unsigned long lock_flags;
 	struct dpu_hw_intf_cfg intf_cfg = { 0 };
 
+	drm_mode_init(&mode, &phys_enc->cached_mode);
+
 	if (!phys_enc->hw_ctl->ops.setup_intf_cfg) {
 		DPU_ERROR("invalid encoder %d\n", phys_enc != NULL);
 		return;
 	}
 
-	mode = phys_enc->cached_mode;
 	if (!phys_enc->hw_intf->ops.setup_timing_gen) {
 		DPU_ERROR("timing engine setup is not supported\n");
 		return;
@@ -634,7 +635,9 @@ static int dpu_encoder_phys_vid_get_frame_count(
 {
 	struct intf_status s = {0};
 	u32 fetch_start = 0;
-	struct drm_display_mode mode = phys_enc->cached_mode;
+	struct drm_display_mode mode;
+
+	drm_mode_init(&mode, &phys_enc->cached_mode);
 
 	if (!dpu_encoder_phys_vid_is_master(phys_enc))
 		return -EINVAL;
-- 
2.37.4

[PATCH v2 4/7] drm/msm: Use drm_mode_copy()

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

struct drm_display_mode embeds a list head, so overwriting
the full struct with another one will corrupt the list
(if the destination mode is on a list). Use drm_mode_copy()
instead which explicitly preserves the list head of
the destination mode.

Even if we know the destination mode is not on any list
using drm_mode_copy() seems decent as it sets a good
example. Bad examples of not using it might eventually
get copied into code where preserving the list head
actually matters.

Obviously one case not covered here is when the mode
itself is embedded in a larger structure and the whole
structure is copied. But if we are careful when copying
into modes embedded in structures I think we can be a
little more reassured that bogus list heads haven't been
propagated in.

@is_mode_copy@
@@
drm_mode_copy(...)
{
...
}

@depends on !is_mode_copy@
struct drm_display_mode *mode;
expression E, S;
@@
(
- *mode = E
+ drm_mode_copy(mode, &E)
|
- memcpy(mode, E, S)
+ drm_mode_copy(mode, E)
)

@depends on !is_mode_copy@
struct drm_display_mode mode;
expression E;
@@
(
- mode = E
+ drm_mode_copy(&mode, &E)
|
- memcpy(&mode, E, S)
+ drm_mode_copy(&mode, E)
)

@@
struct drm_display_mode *mode;
@@
- &*mode
+ mode

Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <sean@poorly.run>
Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/msm/dp/dp_display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index a49f6dbbe888..c9d9b384ddd0 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -857,7 +857,7 @@ static int dp_display_set_mode(struct msm_dp *dp_display,
 
 	dp = container_of(dp_display, struct dp_display_private, dp_display);
 
-	dp->panel->dp_mode.drm_mode = mode->drm_mode;
+	drm_mode_copy(&dp->panel->dp_mode.drm_mode, &mode->drm_mode);
 	dp->panel->dp_mode.bpp = mode->bpp;
 	dp->panel->dp_mode.capabilities = mode->capabilities;
 	dp_panel_init_panel_info(dp->panel);
-- 
2.37.4