From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Thu, 25 Jan 2018 15:30:20 +0200
Subject: drm: Warn if plane/crtc/encoder/connector index exceeds our 32bit
 bitmasks
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Git-commit: 2a8d3eac3d6e11638893ec3c4ba8bc5884db2ef9
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

We use 32bit bitmasks to track planes/crtcs/encoders/connectors.
Naturally we can only do that if the index of those objects stays
below 32. Issue a warning whenever we exceed that limit, hopefully
prompting someone to fix the problem.

For connectors the issue is a bit more complicated as they can
be created/destroyed at runtime due to MST. So the problem is no
longer a purely theoretical programmer error. As the connector
indexes are allocated via ida, we can simply limit the maximum
value the ida is allowed to hand out. The error handling is already
in place.

v2: Return an error to the caller (Harry)
v3: Print a debug message so that we know what happened (Maarten)

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180125133020.23845-1-ville.syrjala@linux.intel.com
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/drm_connector.c |    9 +++++++--
 drivers/gpu/drm/drm_crtc.c      |    4 ++++
 drivers/gpu/drm/drm_encoder.c   |    4 ++++
 drivers/gpu/drm/drm_plane.c     |    4 ++++
 4 files changed, 19 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -205,9 +205,14 @@ int drm_connector_init(struct drm_device
 	connector->dev = dev;
 	connector->funcs = funcs;
 
-	ret = ida_simple_get(&config->connector_ida, 0, 0, GFP_KERNEL);
-	if (ret < 0)
+	/* connector index is used with 32bit bitmasks */
+	ret = ida_simple_get(&config->connector_ida, 0, 32, GFP_KERNEL);
+	if (ret < 0) {
+		DRM_DEBUG_KMS("Failed to allocate %s connector index: %d\n",
+			      drm_connector_enum_list[connector_type].name,
+			      ret);
 		goto out_put;
+	}
 	connector->index = ret;
 	ret = 0;
 
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -282,6 +282,10 @@ int drm_crtc_init_with_planes(struct drm
 	WARN_ON(primary && primary->type != DRM_PLANE_TYPE_PRIMARY);
 	WARN_ON(cursor && cursor->type != DRM_PLANE_TYPE_CURSOR);
 
+	/* crtc index is used with 32bit bitmasks */
+	if (WARN_ON(config->num_crtc >= 32))
+		return -EINVAL;
+
 	crtc->dev = dev;
 	crtc->funcs = funcs;
 
--- a/drivers/gpu/drm/drm_encoder.c
+++ b/drivers/gpu/drm/drm_encoder.c
@@ -110,6 +110,10 @@ int drm_encoder_init(struct drm_device *
 {
 	int ret;
 
+	/* encoder index is used with 32bit bitmasks */
+	if (WARN_ON(dev->mode_config.num_encoder >= 32))
+		return -EINVAL;
+
 	ret = drm_mode_object_add(dev, &encoder->base, DRM_MODE_OBJECT_ENCODER);
 	if (ret)
 		return ret;
--- a/drivers/gpu/drm/drm_plane.c
+++ b/drivers/gpu/drm/drm_plane.c
@@ -173,6 +173,10 @@ int drm_universal_plane_init(struct drm_
 	unsigned int format_modifier_count = 0;
 	int ret;
 
+	/* plane index is used with 32bit bitmasks */
+	if (WARN_ON(config->num_total_plane >= 32))
+		return -EINVAL;
+
 	ret = drm_mode_object_add(dev, &plane->base, DRM_MODE_OBJECT_PLANE);
 	if (ret)
 		return ret;