[PATCH v3 0/5] drm: Provide framebuffer vmap helpers

[PATCH v3 0/5] drm: Provide framebuffer vmap helpers

[Thomas Zimmermann]

Add the new helpers drm_gem_fb_vmap() and drm_gem_fb_vunmap(), which
provide vmap/vunmap for all BOs of a framebuffer. Convert shadow-
plane helpers, gud and vkms.

Callers of GEM vmap and vunmap functions used to do the minimum work
or get some detail wrong. Therefore shadow-plane helpers were intro-
duced to implement the details for all callers. The vmapping code in
the shadow-plane helpers is also useful for gud and vkms. So it makes
sense to provide rsp helpers. Simply call drm_gem_fb_vmap() to
retrieve mappings of all of a framebuffer's BOs.

Future work: besides the mapping's addresses, drm_gem_fb_vmap() should
also return the mappings with the framebuffer data offset added. These
are the addresses were the actual image data is located. A follow-up
set of patches will implement this feature.

v3:
	* free instances of struct vkms_writeback_job on cleanup
	  or errors
v2:
	* update commit message for first patch (Maxime)
	* fix error handling after DRM_FORMAT_MAX_PLANES changes
	  (kernel test robot)
	* fix includes (kernel test robot)
	* use [static N] notations for array parameters

Thomas Zimmermann (5):
  drm: Define DRM_FORMAT_MAX_PLANES
  drm/gem: Provide drm_gem_fb_{vmap,vunmap}()
  drm/gem: Clear mapping addresses for unused framebuffer planes
  drm/gud: Map framebuffer BOs with drm_gem_fb_vmap()
  drm/vkms: Map output framebuffer BOs with drm_gem_fb_vmap()

 drivers/gpu/drm/drm_gem_atomic_helper.c      | 37 +-------
 drivers/gpu/drm/drm_gem_framebuffer_helper.c | 96 ++++++++++++++++++--
 drivers/gpu/drm/gud/gud_pipe.c               | 10 +-
 drivers/gpu/drm/vkms/vkms_composer.c         |  2 +-
 drivers/gpu/drm/vkms/vkms_drv.h              |  6 +-
 drivers/gpu/drm/vkms/vkms_writeback.c        | 28 +++---
 include/drm/drm_fourcc.h                     | 13 ++-
 include/drm/drm_framebuffer.h                |  8 +-
 include/drm/drm_gem_atomic_helper.h          |  3 +-
 include/drm/drm_gem_framebuffer_helper.h     |  6 ++
 10 files changed, 139 insertions(+), 70 deletions(-)


base-commit: 2bda1ca4d4acb4892556fec3a7ea1f02afcd40bb
prerequisite-patch-id: c2b2f08f0eccc9f5df0c0da49fa1d36267deb11d
prerequisite-patch-id: c67e5d886a47b7d0266d81100837557fda34cb24
--
2.32.0

[PATCH v3 1/5] drm: Define DRM_FORMAT_MAX_PLANES

[Thomas Zimmermann]

DRM uses a magic number of 4 for the maximum number of planes per color
format. Declare this constant via DRM_FORMAT_MAX_PLANES and update the
related code. Some code depends on the length of arrays that are now
declared with DRM_FORMAT_MAX_PLANES. Convert it from '4' to ARRAY_SIZE.

v2:
	* mention usage of ARRAY_SIZE() in the commit message (Maxime)
	* also fix error handling in drm_gem_fb_init_with_funcs()
	  (kernel test robot)
	* include <drm/drm_fourcc.h> for DRM_FORMAT_MAX_PLANES

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
---
 drivers/gpu/drm/drm_gem_framebuffer_helper.c | 19 +++++++++++--------
 include/drm/drm_fourcc.h                     | 13 +++++++++----
 include/drm/drm_framebuffer.h                |  8 ++++----
 include/drm/drm_gem_atomic_helper.h          |  3 ++-
 4 files changed, 26 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
index 67bc9edc1d98..421e029a6b3e 100644
--- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c
+++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
@@ -48,7 +48,7 @@
 struct drm_gem_object *drm_gem_fb_get_obj(struct drm_framebuffer *fb,
 					  unsigned int plane)
 {
-	if (plane >= 4)
+	if (plane >= ARRAY_SIZE(fb->obj))
 		return NULL;
 
 	return fb->obj[plane];
@@ -62,7 +62,8 @@ drm_gem_fb_init(struct drm_device *dev,
 		 struct drm_gem_object **obj, unsigned int num_planes,
 		 const struct drm_framebuffer_funcs *funcs)
 {
-	int ret, i;
+	unsigned int i;
+	int ret;
 
 	drm_helper_mode_fill_fb_struct(dev, fb, mode_cmd);
 
@@ -86,9 +87,9 @@ drm_gem_fb_init(struct drm_device *dev,
  */
 void drm_gem_fb_destroy(struct drm_framebuffer *fb)
 {
-	int i;
+	size_t i;
 
-	for (i = 0; i < 4; i++)
+	for (i = 0; i < ARRAY_SIZE(fb->obj); i++)
 		drm_gem_object_put(fb->obj[i]);
 
 	drm_framebuffer_cleanup(fb);
@@ -145,8 +146,9 @@ int drm_gem_fb_init_with_funcs(struct drm_device *dev,
 			       const struct drm_framebuffer_funcs *funcs)
 {
 	const struct drm_format_info *info;
-	struct drm_gem_object *objs[4];
-	int ret, i;
+	struct drm_gem_object *objs[DRM_FORMAT_MAX_PLANES];
+	unsigned int i;
+	int ret;
 
 	info = drm_get_format_info(dev, mode_cmd);
 	if (!info) {
@@ -187,9 +189,10 @@ int drm_gem_fb_init_with_funcs(struct drm_device *dev,
 	return 0;
 
 err_gem_object_put:
-	for (i--; i >= 0; i--)
+	while (i > 0) {
+		--i;
 		drm_gem_object_put(objs[i]);
-
+	}
 	return ret;
 }
 EXPORT_SYMBOL_GPL(drm_gem_fb_init_with_funcs);
diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
index 3b138d4ae67e..22aa64d07c79 100644
--- a/include/drm/drm_fourcc.h
+++ b/include/drm/drm_fourcc.h
@@ -25,6 +25,11 @@
 #include <linux/types.h>
 #include <uapi/drm/drm_fourcc.h>
 
+/**
+ * DRM_FORMAT_MAX_PLANES - maximum number of planes a DRM format can have
+ */
+#define DRM_FORMAT_MAX_PLANES	4u
+
 /*
  * DRM formats are little endian.  Define host endian variants for the
  * most common formats here, to reduce the #ifdefs needed in drivers.
@@ -78,7 +83,7 @@ struct drm_format_info {
 		 * triplet @char_per_block, @block_w, @block_h for better
 		 * describing the pixel format.
 		 */
-		u8 cpp[4];
+		u8 cpp[DRM_FORMAT_MAX_PLANES];
 
 		/**
 		 * @char_per_block:
@@ -104,7 +109,7 @@ struct drm_format_info {
 		 * information from their drm_mode_config.get_format_info hook
 		 * if they want the core to be validating the pitch.
 		 */
-		u8 char_per_block[4];
+		u8 char_per_block[DRM_FORMAT_MAX_PLANES];
 	};
 
 	/**
@@ -113,7 +118,7 @@ struct drm_format_info {
 	 * Block width in pixels, this is intended to be accessed through
 	 * drm_format_info_block_width()
 	 */
-	u8 block_w[4];
+	u8 block_w[DRM_FORMAT_MAX_PLANES];
 
 	/**
 	 * @block_h:
@@ -121,7 +126,7 @@ struct drm_format_info {
 	 * Block height in pixels, this is intended to be accessed through
 	 * drm_format_info_block_height()
 	 */
-	u8 block_h[4];
+	u8 block_h[DRM_FORMAT_MAX_PLANES];
 
 	/** @hsub: Horizontal chroma subsampling factor */
 	u8 hsub;
diff --git a/include/drm/drm_framebuffer.h b/include/drm/drm_framebuffer.h
index be658ebbec72..f67c5b7bcb68 100644
--- a/include/drm/drm_framebuffer.h
+++ b/include/drm/drm_framebuffer.h
@@ -27,12 +27,12 @@
 #include <linux/list.h>
 #include <linux/sched.h>
 
+#include <drm/drm_fourcc.h>
 #include <drm/drm_mode_object.h>
 
 struct drm_clip_rect;
 struct drm_device;
 struct drm_file;
-struct drm_format_info;
 struct drm_framebuffer;
 struct drm_gem_object;
 
@@ -147,7 +147,7 @@ struct drm_framebuffer {
 	 * @pitches: Line stride per buffer. For userspace created object this
 	 * is copied from drm_mode_fb_cmd2.
 	 */
-	unsigned int pitches[4];
+	unsigned int pitches[DRM_FORMAT_MAX_PLANES];
 	/**
 	 * @offsets: Offset from buffer start to the actual pixel data in bytes,
 	 * per buffer. For userspace created object this is copied from
@@ -165,7 +165,7 @@ struct drm_framebuffer {
 	 * data (even for linear buffers). Specifying an x/y pixel offset is
 	 * instead done through the source rectangle in &struct drm_plane_state.
 	 */
-	unsigned int offsets[4];
+	unsigned int offsets[DRM_FORMAT_MAX_PLANES];
 	/**
 	 * @modifier: Data layout modifier. This is used to describe
 	 * tiling, or also special layouts (like compression) of auxiliary
@@ -210,7 +210,7 @@ struct drm_framebuffer {
 	 * This is used by the GEM framebuffer helpers, see e.g.
 	 * drm_gem_fb_create().
 	 */
-	struct drm_gem_object *obj[4];
+	struct drm_gem_object *obj[DRM_FORMAT_MAX_PLANES];
 };
 
 #define obj_to_fb(x) container_of(x, struct drm_framebuffer, base)
diff --git a/include/drm/drm_gem_atomic_helper.h b/include/drm/drm_gem_atomic_helper.h
index d82c23622156..f9f8b6f0494a 100644
--- a/include/drm/drm_gem_atomic_helper.h
+++ b/include/drm/drm_gem_atomic_helper.h
@@ -5,6 +5,7 @@
 
 #include <linux/dma-buf-map.h>
 
+#include <drm/drm_fourcc.h>
 #include <drm/drm_plane.h>
 
 struct drm_simple_display_pipe;
@@ -40,7 +41,7 @@ struct drm_shadow_plane_state {
 	 * The memory mappings stored in map should be established in the plane's
 	 * prepare_fb callback and removed in the cleanup_fb callback.
 	 */
-	struct dma_buf_map map[4];
+	struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];
 };
 
 /**
-- 
2.32.0

[PATCH v3 2/5] drm/gem: Provide drm_gem_fb_{vmap,vunmap}()

[Thomas Zimmermann]

Move framebuffer vmap code from shadow-buffered plane state into the new
interfaces drm_gem_fb_vmap() and drm_gem_fb_vunmap(). These functions
provide mappings of a framebuffer's BOs into kernel address space. No
functional changes.

v2:
	* using [static N] for array parameters enables compile-time checks
	* include <drm/drm_fourcc.h> for DRM_FORMAT_MAX_PLANES (kernel
	  test robot)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
---
 drivers/gpu/drm/drm_gem_atomic_helper.c      | 37 +---------
 drivers/gpu/drm/drm_gem_framebuffer_helper.c | 73 ++++++++++++++++++++
 include/drm/drm_gem_framebuffer_helper.h     |  6 ++
 3 files changed, 82 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_atomic_helper.c b/drivers/gpu/drm/drm_gem_atomic_helper.c
index 26af09b959d4..b1cc19e47165 100644
--- a/drivers/gpu/drm/drm_gem_atomic_helper.c
+++ b/drivers/gpu/drm/drm_gem_atomic_helper.c
@@ -330,10 +330,7 @@ int drm_gem_prepare_shadow_fb(struct drm_plane *plane, struct drm_plane_state *p
 {
 	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
 	struct drm_framebuffer *fb = plane_state->fb;
-	struct drm_gem_object *obj;
-	struct dma_buf_map map;
 	int ret;
-	size_t i;
 
 	if (!fb)
 		return 0;
@@ -342,27 +339,7 @@ int drm_gem_prepare_shadow_fb(struct drm_plane *plane, struct drm_plane_state *p
 	if (ret)
 		return ret;
 
-	for (i = 0; i < ARRAY_SIZE(shadow_plane_state->map); ++i) {
-		obj = drm_gem_fb_get_obj(fb, i);
-		if (!obj)
-			continue;
-		ret = drm_gem_vmap(obj, &map);
-		if (ret)
-			goto err_drm_gem_vunmap;
-		shadow_plane_state->map[i] = map;
-	}
-
-	return 0;
-
-err_drm_gem_vunmap:
-	while (i) {
-		--i;
-		obj = drm_gem_fb_get_obj(fb, i);
-		if (!obj)
-			continue;
-		drm_gem_vunmap(obj, &shadow_plane_state->map[i]);
-	}
-	return ret;
+	return drm_gem_fb_vmap(fb, shadow_plane_state->map);
 }
 EXPORT_SYMBOL(drm_gem_prepare_shadow_fb);
 
@@ -374,25 +351,17 @@ EXPORT_SYMBOL(drm_gem_prepare_shadow_fb);
  * This function implements struct &drm_plane_helper_funcs.cleanup_fb.
  * This function unmaps all buffer objects of the plane's framebuffer.
  *
- * See drm_gem_prepare_shadow_fb() for more inforamtion.
+ * See drm_gem_prepare_shadow_fb() for more information.
  */
 void drm_gem_cleanup_shadow_fb(struct drm_plane *plane, struct drm_plane_state *plane_state)
 {
 	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
 	struct drm_framebuffer *fb = plane_state->fb;
-	size_t i = ARRAY_SIZE(shadow_plane_state->map);
-	struct drm_gem_object *obj;
 
 	if (!fb)
 		return;
 
-	while (i) {
-		--i;
-		obj = drm_gem_fb_get_obj(fb, i);
-		if (!obj)
-			continue;
-		drm_gem_vunmap(obj, &shadow_plane_state->map[i]);
-	}
+	drm_gem_fb_vunmap(fb, shadow_plane_state->map);
 }
 EXPORT_SYMBOL(drm_gem_cleanup_shadow_fb);
 
diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
index 421e029a6b3e..243affbad437 100644
--- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c
+++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
@@ -15,6 +15,8 @@
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_modeset_helper.h>
 
+#include "drm_internal.h"
+
 #define AFBC_HEADER_SIZE		16
 #define AFBC_TH_LAYOUT_ALIGNMENT	8
 #define AFBC_HDR_ALIGN			64
@@ -309,6 +311,77 @@ drm_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file *file,
 }
 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_dirty);
 
+
+/**
+ * drm_gem_fb_vmap - maps all framebuffer BOs into kernel address space
+ * @fb: the framebuffer
+ * @map: returns the mapping's address for each BO
+ *
+ * This function maps all buffer objects of the given framebuffer into
+ * kernel address space and stores them in struct dma_buf_map. If the
+ * mapping operation fails for one of the BOs, the function unmaps the
+ * already established mappings automatically.
+ *
+ * See drm_gem_fb_vunmap() for unmapping.
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise.
+ */
+int drm_gem_fb_vmap(struct drm_framebuffer *fb,
+		    struct dma_buf_map map[static DRM_FORMAT_MAX_PLANES])
+{
+	struct drm_gem_object *obj;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < DRM_FORMAT_MAX_PLANES; ++i) {
+		obj = drm_gem_fb_get_obj(fb, i);
+		if (!obj)
+			continue;
+		ret = drm_gem_vmap(obj, &map[i]);
+		if (ret)
+			goto err_drm_gem_vunmap;
+	}
+
+	return 0;
+
+err_drm_gem_vunmap:
+	while (i) {
+		--i;
+		obj = drm_gem_fb_get_obj(fb, i);
+		if (!obj)
+			continue;
+		drm_gem_vunmap(obj, &map[i]);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_fb_vmap);
+
+/**
+ * drm_gem_fb_vunmap - unmaps framebuffer BOs from kernel address space
+ * @fb: the framebuffer
+ * @map: mapping addresses as returned by drm_gem_fb_vmap()
+ *
+ * This function unmaps all buffer objects of the given framebuffer.
+ *
+ * See drm_gem_fb_vmap() for more information.
+ */
+void drm_gem_fb_vunmap(struct drm_framebuffer *fb,
+		       struct dma_buf_map map[static DRM_FORMAT_MAX_PLANES])
+{
+	unsigned int i = DRM_FORMAT_MAX_PLANES;
+	struct drm_gem_object *obj;
+
+	while (i) {
+		--i;
+		obj = drm_gem_fb_get_obj(fb, i);
+		if (!obj)
+			continue;
+		drm_gem_vunmap(obj, &map[i]);
+	}
+}
+EXPORT_SYMBOL(drm_gem_fb_vunmap);
+
 /**
  * drm_gem_fb_begin_cpu_access - prepares GEM buffer objects for CPU access
  * @fb: the framebuffer
diff --git a/include/drm/drm_gem_framebuffer_helper.h b/include/drm/drm_gem_framebuffer_helper.h
index 5705722f0855..ff2024dd7b77 100644
--- a/include/drm/drm_gem_framebuffer_helper.h
+++ b/include/drm/drm_gem_framebuffer_helper.h
@@ -4,6 +4,8 @@
 #include <linux/dma-buf.h>
 #include <linux/dma-buf-map.h>
 
+#include <drm/drm_fourcc.h>
+
 struct drm_afbc_framebuffer;
 struct drm_device;
 struct drm_fb_helper_surface_size;
@@ -37,6 +39,10 @@ struct drm_framebuffer *
 drm_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file *file,
 			     const struct drm_mode_fb_cmd2 *mode_cmd);
 
+int drm_gem_fb_vmap(struct drm_framebuffer *fb,
+		    struct dma_buf_map map[static DRM_FORMAT_MAX_PLANES]);
+void drm_gem_fb_vunmap(struct drm_framebuffer *fb,
+		       struct dma_buf_map map[static DRM_FORMAT_MAX_PLANES]);
 int drm_gem_fb_begin_cpu_access(struct drm_framebuffer *fb, enum dma_data_direction dir);
 void drm_gem_fb_end_cpu_access(struct drm_framebuffer *fb, enum dma_data_direction dir);
 
-- 
2.32.0

[PATCH v3 3/5] drm/gem: Clear mapping addresses for unused framebuffer planes

[Thomas Zimmermann]

Set the returned mapping address to NULL if a framebuffer plane does
not have a BO associated with it. Likewise, ignore mappings of NULL
during framebuffer unmap operations. Allows users of the functions to
perform unmap operations of certain BOs by themselfes.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
---
 drivers/gpu/drm/drm_gem_framebuffer_helper.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
index 243affbad437..02928607a716 100644
--- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c
+++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
@@ -336,8 +336,10 @@ int drm_gem_fb_vmap(struct drm_framebuffer *fb,
 
 	for (i = 0; i < DRM_FORMAT_MAX_PLANES; ++i) {
 		obj = drm_gem_fb_get_obj(fb, i);
-		if (!obj)
+		if (!obj) {
+			dma_buf_map_clear(&map[i]);
 			continue;
+		}
 		ret = drm_gem_vmap(obj, &map[i]);
 		if (ret)
 			goto err_drm_gem_vunmap;
@@ -377,6 +379,8 @@ void drm_gem_fb_vunmap(struct drm_framebuffer *fb,
 		obj = drm_gem_fb_get_obj(fb, i);
 		if (!obj)
 			continue;
+		if (dma_buf_map_is_null(&map[i]))
+			continue;
 		drm_gem_vunmap(obj, &map[i]);
 	}
 }
-- 
2.32.0

[PATCH v3 4/5] drm/gud: Map framebuffer BOs with drm_gem_fb_vmap()

[Thomas Zimmermann]

Abstract the framebuffer details by mapping its BOs with a call
to drm_gem_fb_vmap(). Unmap with drm_gem_fb_vunmap().

The call to drm_gem_fb_vmap() ensures that all BOs are mapped
correctly. Gud still only supports single-plane formats.

No functional changes.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
 drivers/gpu/drm/gud/gud_pipe.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c
index 4d7a26b68a2e..7e009f562b30 100644
--- a/drivers/gpu/drm/gud/gud_pipe.c
+++ b/drivers/gpu/drm/gud/gud_pipe.c
@@ -14,8 +14,8 @@
 #include <drm/drm_format_helper.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_framebuffer.h>
+#include <drm/drm_gem.h>
 #include <drm/drm_gem_framebuffer_helper.h>
-#include <drm/drm_gem_shmem_helper.h>
 #include <drm/drm_print.h>
 #include <drm/drm_rect.h>
 #include <drm/drm_simple_kms_helper.h>
@@ -152,7 +152,7 @@ static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
 {
 	struct dma_buf_attachment *import_attach = fb->obj[0]->import_attach;
 	u8 compression = gdrm->compression;
-	struct dma_buf_map map;
+	struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];
 	void *vaddr, *buf;
 	size_t pitch, len;
 	int ret = 0;
@@ -162,11 +162,11 @@ static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
 	if (len > gdrm->bulk_len)
 		return -E2BIG;
 
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
+	ret = drm_gem_fb_vmap(fb, map);
 	if (ret)
 		return ret;
 
-	vaddr = map.vaddr + fb->offsets[0];
+	vaddr = map[0].vaddr + fb->offsets[0];
 
 	ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
 	if (ret)
@@ -225,7 +225,7 @@ static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
 end_cpu_access:
 	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
 vunmap:
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
+	drm_gem_fb_vunmap(fb, map);
 
 	return ret;
 }
-- 
2.32.0

Re: [PATCH v3 4/5] drm/gud: Map framebuffer BOs with drm_gem_fb_vmap()

[Noralf Trønnes]

Hi Thomas,

I'm getting this on Ubuntu 22.04:

[    0.000000] Linux version 5.15.0-27-generic (buildd@ubuntu) (gcc
(Ubuntu 11.2.0-19ubuntu1) 11.2.0, GNU ld (GNU Binutils for Ubuntu) 2.38)
#28-Ubuntu SMP Thu Apr 14 04:55:28 UTC 2022 (Ubuntu 5.15.0-27.28-generic
5.15.30)

[    4.830866] usb 2-3.1: new high-speed USB device number 4 using xhci_hcd
[    4.935546] usb 2-3.1: New USB device found, idVendor=1d50,
idProduct=614d, bcdDevice= 1.00
[    4.935553] usb 2-3.1: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[    4.935556] usb 2-3.1: Product: Raspberry Pi 4 Display Gadget
[    4.935558] usb 2-3.1: Manufacturer: Raspberry Pi
[    4.935560] usb 2-3.1: SerialNumber: 100000003b40d6c6

[    7.497361] [drm] Initialized gud 1.0.0 20200422 for 2-3.1:1.0 on minor 0

[    7.573048] gud 2-3.1:1.0: [drm] fb1: guddrmfb frame buffer device

[    9.199402]
================================================================================
[    9.199411] UBSAN: invalid-load in
/build/linux-HMZHpV/linux-5.15.0/include/linux/dma-buf-map.h:224:9
[    9.199416] load of value 226 is not a valid value for type '_Bool'
[    9.199420] CPU: 0 PID: 113 Comm: kworker/0:2 Not tainted
5.15.0-27-generic #28-Ubuntu
[    9.199424] Hardware name: Hewlett-Packard HP EliteBook 820 G1/1991,
BIOS L71 Ver. 01.44 04/12/2018
[    9.199427] Workqueue: events_long gud_flush_work [gud]
[    9.199440] Call Trace:
[    9.199443]  <TASK>
[    9.199447]  show_stack+0x52/0x58
[    9.199456]  dump_stack_lvl+0x4a/0x5f
[    9.199464]  dump_stack+0x10/0x12
[    9.199468]  ubsan_epilogue+0x9/0x45
[    9.199473]  __ubsan_handle_load_invalid_value.cold+0x44/0x49
[    9.199478]  drm_gem_fb_vmap.cold+0x10/0x3d [drm_kms_helper]
[    9.199519]  gud_prep_flush+0xaa/0x410 [gud]
[    9.199525]  ? check_preempt_curr+0x5d/0x70
[    9.199533]  ? update_load_avg+0x82/0x620
[    9.199540]  ? set_next_entity+0xb7/0x200
[    9.199545]  gud_flush_work+0x1e0/0x430 [gud]
[    9.199551]  ? psi_task_switch+0x1e7/0x220
[    9.199557]  process_one_work+0x22b/0x3d0
[    9.199564]  worker_thread+0x53/0x410
[    9.199570]  ? process_one_work+0x3d0/0x3d0
[    9.199575]  kthread+0x12a/0x150
[    9.199579]  ? set_kthread_struct+0x50/0x50
[    9.199584]  ret_from_fork+0x22/0x30
[    9.199593]  </TASK>
[    9.199595]
================================================================================

[    9.199598]
================================================================================
[    9.199600] UBSAN: invalid-load in
/build/linux-HMZHpV/linux-5.15.0/include/linux/dma-buf-map.h:194:9
[    9.199604] load of value 226 is not a valid value for type '_Bool'
[    9.199606] CPU: 0 PID: 113 Comm: kworker/0:2 Not tainted
5.15.0-27-generic #28-Ubuntu
[    9.199610] Hardware name: Hewlett-Packard HP EliteBook 820 G1/1991,
BIOS L71 Ver. 01.44 04/12/2018
[    9.199612] Workqueue: events_long gud_flush_work [gud]
[    9.199618] Call Trace:
[    9.199619]  <TASK>
[    9.199621]  show_stack+0x52/0x58
[    9.199627]  dump_stack_lvl+0x4a/0x5f
[    9.199633]  dump_stack+0x10/0x12
[    9.199637]  ubsan_epilogue+0x9/0x45
[    9.199641]  __ubsan_handle_load_invalid_value.cold+0x44/0x49
[    9.199646]  drm_gem_fb_vmap.cold+0x24/0x3d [drm_kms_helper]
[    9.199675]  gud_prep_flush+0xaa/0x410 [gud]
[    9.199682]  ? check_preempt_curr+0x5d/0x70
[    9.199688]  ? update_load_avg+0x82/0x620
[    9.199693]  ? update_load_avg+0x82/0x620
[    9.199697]  gud_flush_work+0x1e0/0x430 [gud]
[    9.199702]  ? psi_task_switch+0x1e7/0x220
[    9.199706]  process_one_work+0x22b/0x3d0
[    9.199713]  worker_thread+0x53/0x410
[    9.199718]  ? process_one_work+0x3d0/0x3d0
[    9.199723]  kthread+0x12a/0x150
[    9.199728]  ? set_kthread_struct+0x50/0x50
[    9.199732]  ret_from_fork+0x22/0x30
[    9.199741]  </TASK>
[    9.199743]
================================================================================

It's the "if (map->is_iomem)" statement in dma_buf_map_clear() and
dma_buf_map_is_null() that triggers this.

I tried 5.18.0-rc5 and the problem is still present.

UBSAN entries in the config:

CONFIG_ARCH_HAS_UBSAN_SANITIZE_ALL=y
CONFIG_UBSAN=y
# CONFIG_UBSAN_TRAP is not set
CONFIG_CC_HAS_UBSAN_BOUNDS=y
CONFIG_UBSAN_BOUNDS=y
CONFIG_UBSAN_ONLY_BOUNDS=y
CONFIG_UBSAN_SHIFT=y
# CONFIG_UBSAN_DIV_ZERO is not set
CONFIG_UBSAN_BOOL=y
CONFIG_UBSAN_ENUM=y
# CONFIG_UBSAN_ALIGNMENT is not set
CONFIG_UBSAN_SANITIZE_ALL=y
# CONFIG_TEST_UBSAN is not set

Continuing further down.


Den 30.07.2021 20.35, skrev Thomas Zimmermann:
> Abstract the framebuffer details by mapping its BOs with a call
> to drm_gem_fb_vmap(). Unmap with drm_gem_fb_vunmap().
> 
> The call to drm_gem_fb_vmap() ensures that all BOs are mapped
> correctly. Gud still only supports single-plane formats.
> 
> No functional changes.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Acked-by: Noralf Trønnes <noralf@tronnes.org>
> Acked-by: Sam Ravnborg <sam@ravnborg.org>
> ---
>  drivers/gpu/drm/gud/gud_pipe.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c
> index 4d7a26b68a2e..7e009f562b30 100644
> --- a/drivers/gpu/drm/gud/gud_pipe.c
> +++ b/drivers/gpu/drm/gud/gud_pipe.c
> @@ -14,8 +14,8 @@
>  #include <drm/drm_format_helper.h>
>  #include <drm/drm_fourcc.h>
>  #include <drm/drm_framebuffer.h>
> +#include <drm/drm_gem.h>
>  #include <drm/drm_gem_framebuffer_helper.h>
> -#include <drm/drm_gem_shmem_helper.h>
>  #include <drm/drm_print.h>
>  #include <drm/drm_rect.h>
>  #include <drm/drm_simple_kms_helper.h>
> @@ -152,7 +152,7 @@ static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
>  {
>  	struct dma_buf_attachment *import_attach = fb->obj[0]->import_attach;
>  	u8 compression = gdrm->compression;
> -	struct dma_buf_map map;
> +	struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];

Zeroing map solves the problem:

        struct iosys_map map[DRM_FORMAT_MAX_PLANES] = {};

I don't understand the conditional clearing in
dma_buf_map_clear/iosys_map_clear(), the doc says: Clears all fields to
zero. If I zero the whole structure unconditionally this also keeps
UBSAN happy.

Noralf.

>  	void *vaddr, *buf;
>  	size_t pitch, len;
>  	int ret = 0;
> @@ -162,11 +162,11 @@ static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
>  	if (len > gdrm->bulk_len)
>  		return -E2BIG;
>  
> -	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
> +	ret = drm_gem_fb_vmap(fb, map);
>  	if (ret)
>  		return ret;
>  
> -	vaddr = map.vaddr + fb->offsets[0];
> +	vaddr = map[0].vaddr + fb->offsets[0];
>  
>  	ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
>  	if (ret)
> @@ -225,7 +225,7 @@ static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
>  end_cpu_access:
>  	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
>  vunmap:
> -	drm_gem_shmem_vunmap(fb->obj[0], &map);
> +	drm_gem_fb_vunmap(fb, map);
>  
>  	return ret;
>  }

Re: [PATCH v3 4/5] drm/gud: Map framebuffer BOs with drm_gem_fb_vmap()

[Thomas Zimmermann]

[-- Attachment #1.1: Type: text/plain, Size: 8043 bytes --]

Hi

Am 06.05.22 um 16:01 schrieb Noralf Trønnes:
> Hi Thomas,
> 
> I'm getting this on Ubuntu 22.04:
> 
> [    0.000000] Linux version 5.15.0-27-generic (buildd@ubuntu) (gcc
> (Ubuntu 11.2.0-19ubuntu1) 11.2.0, GNU ld (GNU Binutils for Ubuntu) 2.38)
> #28-Ubuntu SMP Thu Apr 14 04:55:28 UTC 2022 (Ubuntu 5.15.0-27.28-generic
> 5.15.30)
> 
> [    4.830866] usb 2-3.1: new high-speed USB device number 4 using xhci_hcd
> [    4.935546] usb 2-3.1: New USB device found, idVendor=1d50,
> idProduct=614d, bcdDevice= 1.00
> [    4.935553] usb 2-3.1: New USB device strings: Mfr=1, Product=2,
> SerialNumber=3
> [    4.935556] usb 2-3.1: Product: Raspberry Pi 4 Display Gadget
> [    4.935558] usb 2-3.1: Manufacturer: Raspberry Pi
> [    4.935560] usb 2-3.1: SerialNumber: 100000003b40d6c6
> 
> [    7.497361] [drm] Initialized gud 1.0.0 20200422 for 2-3.1:1.0 on minor 0
> 
> [    7.573048] gud 2-3.1:1.0: [drm] fb1: guddrmfb frame buffer device
> 
> [    9.199402]
> ================================================================================
> [    9.199411] UBSAN: invalid-load in
> /build/linux-HMZHpV/linux-5.15.0/include/linux/dma-buf-map.h:224:9
> [    9.199416] load of value 226 is not a valid value for type '_Bool'
> [    9.199420] CPU: 0 PID: 113 Comm: kworker/0:2 Not tainted
> 5.15.0-27-generic #28-Ubuntu
> [    9.199424] Hardware name: Hewlett-Packard HP EliteBook 820 G1/1991,
> BIOS L71 Ver. 01.44 04/12/2018
> [    9.199427] Workqueue: events_long gud_flush_work [gud]
> [    9.199440] Call Trace:
> [    9.199443]  <TASK>
> [    9.199447]  show_stack+0x52/0x58
> [    9.199456]  dump_stack_lvl+0x4a/0x5f
> [    9.199464]  dump_stack+0x10/0x12
> [    9.199468]  ubsan_epilogue+0x9/0x45
> [    9.199473]  __ubsan_handle_load_invalid_value.cold+0x44/0x49
> [    9.199478]  drm_gem_fb_vmap.cold+0x10/0x3d [drm_kms_helper]
> [    9.199519]  gud_prep_flush+0xaa/0x410 [gud]
> [    9.199525]  ? check_preempt_curr+0x5d/0x70
> [    9.199533]  ? update_load_avg+0x82/0x620
> [    9.199540]  ? set_next_entity+0xb7/0x200
> [    9.199545]  gud_flush_work+0x1e0/0x430 [gud]
> [    9.199551]  ? psi_task_switch+0x1e7/0x220
> [    9.199557]  process_one_work+0x22b/0x3d0
> [    9.199564]  worker_thread+0x53/0x410
> [    9.199570]  ? process_one_work+0x3d0/0x3d0
> [    9.199575]  kthread+0x12a/0x150
> [    9.199579]  ? set_kthread_struct+0x50/0x50
> [    9.199584]  ret_from_fork+0x22/0x30
> [    9.199593]  </TASK>
> [    9.199595]
> ================================================================================
> 
> [    9.199598]
> ================================================================================
> [    9.199600] UBSAN: invalid-load in
> /build/linux-HMZHpV/linux-5.15.0/include/linux/dma-buf-map.h:194:9
> [    9.199604] load of value 226 is not a valid value for type '_Bool'
> [    9.199606] CPU: 0 PID: 113 Comm: kworker/0:2 Not tainted
> 5.15.0-27-generic #28-Ubuntu
> [    9.199610] Hardware name: Hewlett-Packard HP EliteBook 820 G1/1991,
> BIOS L71 Ver. 01.44 04/12/2018
> [    9.199612] Workqueue: events_long gud_flush_work [gud]
> [    9.199618] Call Trace:
> [    9.199619]  <TASK>
> [    9.199621]  show_stack+0x52/0x58
> [    9.199627]  dump_stack_lvl+0x4a/0x5f
> [    9.199633]  dump_stack+0x10/0x12
> [    9.199637]  ubsan_epilogue+0x9/0x45
> [    9.199641]  __ubsan_handle_load_invalid_value.cold+0x44/0x49
> [    9.199646]  drm_gem_fb_vmap.cold+0x24/0x3d [drm_kms_helper]
> [    9.199675]  gud_prep_flush+0xaa/0x410 [gud]
> [    9.199682]  ? check_preempt_curr+0x5d/0x70
> [    9.199688]  ? update_load_avg+0x82/0x620
> [    9.199693]  ? update_load_avg+0x82/0x620
> [    9.199697]  gud_flush_work+0x1e0/0x430 [gud]
> [    9.199702]  ? psi_task_switch+0x1e7/0x220
> [    9.199706]  process_one_work+0x22b/0x3d0
> [    9.199713]  worker_thread+0x53/0x410
> [    9.199718]  ? process_one_work+0x3d0/0x3d0
> [    9.199723]  kthread+0x12a/0x150
> [    9.199728]  ? set_kthread_struct+0x50/0x50
> [    9.199732]  ret_from_fork+0x22/0x30
> [    9.199741]  </TASK>
> [    9.199743]
> ================================================================================
> 
> It's the "if (map->is_iomem)" statement in dma_buf_map_clear() and
> dma_buf_map_is_null() that triggers this.
> 
> I tried 5.18.0-rc5 and the problem is still present.
> 
> UBSAN entries in the config:
> 
> CONFIG_ARCH_HAS_UBSAN_SANITIZE_ALL=y
> CONFIG_UBSAN=y
> # CONFIG_UBSAN_TRAP is not set
> CONFIG_CC_HAS_UBSAN_BOUNDS=y
> CONFIG_UBSAN_BOUNDS=y
> CONFIG_UBSAN_ONLY_BOUNDS=y
> CONFIG_UBSAN_SHIFT=y
> # CONFIG_UBSAN_DIV_ZERO is not set
> CONFIG_UBSAN_BOOL=y
> CONFIG_UBSAN_ENUM=y
> # CONFIG_UBSAN_ALIGNMENT is not set
> CONFIG_UBSAN_SANITIZE_ALL=y
> # CONFIG_TEST_UBSAN is not set
> 
> Continuing further down.
> 
> 
> Den 30.07.2021 20.35, skrev Thomas Zimmermann:
>> Abstract the framebuffer details by mapping its BOs with a call
>> to drm_gem_fb_vmap(). Unmap with drm_gem_fb_vunmap().
>>
>> The call to drm_gem_fb_vmap() ensures that all BOs are mapped
>> correctly. Gud still only supports single-plane formats.
>>
>> No functional changes.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> Acked-by: Noralf Trønnes <noralf@tronnes.org>
>> Acked-by: Sam Ravnborg <sam@ravnborg.org>
>> ---
>>   drivers/gpu/drm/gud/gud_pipe.c | 10 +++++-----
>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c
>> index 4d7a26b68a2e..7e009f562b30 100644
>> --- a/drivers/gpu/drm/gud/gud_pipe.c
>> +++ b/drivers/gpu/drm/gud/gud_pipe.c
>> @@ -14,8 +14,8 @@
>>   #include <drm/drm_format_helper.h>
>>   #include <drm/drm_fourcc.h>
>>   #include <drm/drm_framebuffer.h>
>> +#include <drm/drm_gem.h>
>>   #include <drm/drm_gem_framebuffer_helper.h>
>> -#include <drm/drm_gem_shmem_helper.h>
>>   #include <drm/drm_print.h>
>>   #include <drm/drm_rect.h>
>>   #include <drm/drm_simple_kms_helper.h>
>> @@ -152,7 +152,7 @@ static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
>>   {
>>   	struct dma_buf_attachment *import_attach = fb->obj[0]->import_attach;
>>   	u8 compression = gdrm->compression;
>> -	struct dma_buf_map map;
>> +	struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];
> 
> Zeroing map solves the problem:
> 
>          struct iosys_map map[DRM_FORMAT_MAX_PLANES] = {};
> 
> I don't understand the conditional clearing in
> dma_buf_map_clear/iosys_map_clear(), the doc says: Clears all fields to
> zero. If I zero the whole structure unconditionally this also keeps
> UBSAN happy.

Thanks for debugging this problem. It's uninitialized and some of the 
internal helpers look at all planes, even if they are empty. I have a 
patchset to fix that throughout the DRM modules. I'll post on Monday.

If we need a quick fix, we could do the zeroing everywhere.

Best regards
Thomas

> 
> Noralf.
> 
>>   	void *vaddr, *buf;
>>   	size_t pitch, len;
>>   	int ret = 0;
>> @@ -162,11 +162,11 @@ static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
>>   	if (len > gdrm->bulk_len)
>>   		return -E2BIG;
>>   
>> -	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
>> +	ret = drm_gem_fb_vmap(fb, map);
>>   	if (ret)
>>   		return ret;
>>   
>> -	vaddr = map.vaddr + fb->offsets[0];
>> +	vaddr = map[0].vaddr + fb->offsets[0];
>>   
>>   	ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
>>   	if (ret)
>> @@ -225,7 +225,7 @@ static int gud_prep_flush(struct gud_device *gdrm, struct drm_framebuffer *fb,
>>   end_cpu_access:
>>   	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
>>   vunmap:
>> -	drm_gem_shmem_vunmap(fb->obj[0], &map);
>> +	drm_gem_fb_vunmap(fb, map);
>>   
>>   	return ret;
>>   }

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 840 bytes --]

Re: [PATCH v3 4/5] drm/gud: Map framebuffer BOs with drm_gem_fb_vmap()

[Thomas Zimmermann]

[-- Attachment #1.1: Type: text/plain, Size: 9361 bytes --]

Hi Noralf

Am 06.05.22 um 16:11 schrieb Thomas Zimmermann:
> Hi
> 
> Am 06.05.22 um 16:01 schrieb Noralf Trønnes:
>> Hi Thomas,
>>
>> I'm getting this on Ubuntu 22.04:
>>
>> [    0.000000] Linux version 5.15.0-27-generic (buildd@ubuntu) (gcc
>> (Ubuntu 11.2.0-19ubuntu1) 11.2.0, GNU ld (GNU Binutils for Ubuntu) 2.38)
>> #28-Ubuntu SMP Thu Apr 14 04:55:28 UTC 2022 (Ubuntu 5.15.0-27.28-generic
>> 5.15.30)
>>
>> [    4.830866] usb 2-3.1: new high-speed USB device number 4 using 
>> xhci_hcd
>> [    4.935546] usb 2-3.1: New USB device found, idVendor=1d50,
>> idProduct=614d, bcdDevice= 1.00
>> [    4.935553] usb 2-3.1: New USB device strings: Mfr=1, Product=2,
>> SerialNumber=3
>> [    4.935556] usb 2-3.1: Product: Raspberry Pi 4 Display Gadget
>> [    4.935558] usb 2-3.1: Manufacturer: Raspberry Pi
>> [    4.935560] usb 2-3.1: SerialNumber: 100000003b40d6c6
>>
>> [    7.497361] [drm] Initialized gud 1.0.0 20200422 for 2-3.1:1.0 on 
>> minor 0
>>
>> [    7.573048] gud 2-3.1:1.0: [drm] fb1: guddrmfb frame buffer device
>>
>> [    9.199402]
>> ================================================================================ 
>>
>> [    9.199411] UBSAN: invalid-load in
>> /build/linux-HMZHpV/linux-5.15.0/include/linux/dma-buf-map.h:224:9
>> [    9.199416] load of value 226 is not a valid value for type '_Bool'
>> [    9.199420] CPU: 0 PID: 113 Comm: kworker/0:2 Not tainted
>> 5.15.0-27-generic #28-Ubuntu
>> [    9.199424] Hardware name: Hewlett-Packard HP EliteBook 820 G1/1991,
>> BIOS L71 Ver. 01.44 04/12/2018
>> [    9.199427] Workqueue: events_long gud_flush_work [gud]
>> [    9.199440] Call Trace:
>> [    9.199443]  <TASK>
>> [    9.199447]  show_stack+0x52/0x58
>> [    9.199456]  dump_stack_lvl+0x4a/0x5f
>> [    9.199464]  dump_stack+0x10/0x12
>> [    9.199468]  ubsan_epilogue+0x9/0x45
>> [    9.199473]  __ubsan_handle_load_invalid_value.cold+0x44/0x49
>> [    9.199478]  drm_gem_fb_vmap.cold+0x10/0x3d [drm_kms_helper]
>> [    9.199519]  gud_prep_flush+0xaa/0x410 [gud]
>> [    9.199525]  ? check_preempt_curr+0x5d/0x70
>> [    9.199533]  ? update_load_avg+0x82/0x620
>> [    9.199540]  ? set_next_entity+0xb7/0x200
>> [    9.199545]  gud_flush_work+0x1e0/0x430 [gud]
>> [    9.199551]  ? psi_task_switch+0x1e7/0x220
>> [    9.199557]  process_one_work+0x22b/0x3d0
>> [    9.199564]  worker_thread+0x53/0x410
>> [    9.199570]  ? process_one_work+0x3d0/0x3d0
>> [    9.199575]  kthread+0x12a/0x150
>> [    9.199579]  ? set_kthread_struct+0x50/0x50
>> [    9.199584]  ret_from_fork+0x22/0x30
>> [    9.199593]  </TASK>
>> [    9.199595]
>> ================================================================================ 
>>
>>
>> [    9.199598]
>> ================================================================================ 
>>
>> [    9.199600] UBSAN: invalid-load in
>> /build/linux-HMZHpV/linux-5.15.0/include/linux/dma-buf-map.h:194:9
>> [    9.199604] load of value 226 is not a valid value for type '_Bool'
>> [    9.199606] CPU: 0 PID: 113 Comm: kworker/0:2 Not tainted
>> 5.15.0-27-generic #28-Ubuntu
>> [    9.199610] Hardware name: Hewlett-Packard HP EliteBook 820 G1/1991,
>> BIOS L71 Ver. 01.44 04/12/2018
>> [    9.199612] Workqueue: events_long gud_flush_work [gud]
>> [    9.199618] Call Trace:
>> [    9.199619]  <TASK>
>> [    9.199621]  show_stack+0x52/0x58
>> [    9.199627]  dump_stack_lvl+0x4a/0x5f
>> [    9.199633]  dump_stack+0x10/0x12
>> [    9.199637]  ubsan_epilogue+0x9/0x45
>> [    9.199641]  __ubsan_handle_load_invalid_value.cold+0x44/0x49
>> [    9.199646]  drm_gem_fb_vmap.cold+0x24/0x3d [drm_kms_helper]
>> [    9.199675]  gud_prep_flush+0xaa/0x410 [gud]
>> [    9.199682]  ? check_preempt_curr+0x5d/0x70
>> [    9.199688]  ? update_load_avg+0x82/0x620
>> [    9.199693]  ? update_load_avg+0x82/0x620
>> [    9.199697]  gud_flush_work+0x1e0/0x430 [gud]
>> [    9.199702]  ? psi_task_switch+0x1e7/0x220
>> [    9.199706]  process_one_work+0x22b/0x3d0
>> [    9.199713]  worker_thread+0x53/0x410
>> [    9.199718]  ? process_one_work+0x3d0/0x3d0
>> [    9.199723]  kthread+0x12a/0x150
>> [    9.199728]  ? set_kthread_struct+0x50/0x50
>> [    9.199732]  ret_from_fork+0x22/0x30
>> [    9.199741]  </TASK>
>> [    9.199743]
>> ================================================================================ 
>>
>>
>> It's the "if (map->is_iomem)" statement in dma_buf_map_clear() and
>> dma_buf_map_is_null() that triggers this.
>>
>> I tried 5.18.0-rc5 and the problem is still present.
>>
>> UBSAN entries in the config:
>>
>> CONFIG_ARCH_HAS_UBSAN_SANITIZE_ALL=y
>> CONFIG_UBSAN=y
>> # CONFIG_UBSAN_TRAP is not set
>> CONFIG_CC_HAS_UBSAN_BOUNDS=y
>> CONFIG_UBSAN_BOUNDS=y
>> CONFIG_UBSAN_ONLY_BOUNDS=y
>> CONFIG_UBSAN_SHIFT=y
>> # CONFIG_UBSAN_DIV_ZERO is not set
>> CONFIG_UBSAN_BOOL=y
>> CONFIG_UBSAN_ENUM=y
>> # CONFIG_UBSAN_ALIGNMENT is not set
>> CONFIG_UBSAN_SANITIZE_ALL=y
>> # CONFIG_TEST_UBSAN is not set
>>
>> Continuing further down.
>>
>>
>> Den 30.07.2021 20.35, skrev Thomas Zimmermann:
>>> Abstract the framebuffer details by mapping its BOs with a call
>>> to drm_gem_fb_vmap(). Unmap with drm_gem_fb_vunmap().
>>>
>>> The call to drm_gem_fb_vmap() ensures that all BOs are mapped
>>> correctly. Gud still only supports single-plane formats.
>>>
>>> No functional changes.
>>>
>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>> Acked-by: Noralf Trønnes <noralf@tronnes.org>
>>> Acked-by: Sam Ravnborg <sam@ravnborg.org>
>>> ---
>>>   drivers/gpu/drm/gud/gud_pipe.c | 10 +++++-----
>>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/gud/gud_pipe.c 
>>> b/drivers/gpu/drm/gud/gud_pipe.c
>>> index 4d7a26b68a2e..7e009f562b30 100644
>>> --- a/drivers/gpu/drm/gud/gud_pipe.c
>>> +++ b/drivers/gpu/drm/gud/gud_pipe.c
>>> @@ -14,8 +14,8 @@
>>>   #include <drm/drm_format_helper.h>
>>>   #include <drm/drm_fourcc.h>
>>>   #include <drm/drm_framebuffer.h>
>>> +#include <drm/drm_gem.h>
>>>   #include <drm/drm_gem_framebuffer_helper.h>
>>> -#include <drm/drm_gem_shmem_helper.h>
>>>   #include <drm/drm_print.h>
>>>   #include <drm/drm_rect.h>
>>>   #include <drm/drm_simple_kms_helper.h>
>>> @@ -152,7 +152,7 @@ static int gud_prep_flush(struct gud_device 
>>> *gdrm, struct drm_framebuffer *fb,
>>>   {
>>>       struct dma_buf_attachment *import_attach = 
>>> fb->obj[0]->import_attach;
>>>       u8 compression = gdrm->compression;
>>> -    struct dma_buf_map map;
>>> +    struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];
>>
>> Zeroing map solves the problem:
>>
>>          struct iosys_map map[DRM_FORMAT_MAX_PLANES] = {};
>>
>> I don't understand the conditional clearing in
>> dma_buf_map_clear/iosys_map_clear(), the doc says: Clears all fields to
>> zero. If I zero the whole structure unconditionally this also keeps
>> UBSAN happy.

iomap_sys_clear() assumes that the instance is already initialized. 
Hence, calling it at [1] with un-zeroed, stack-allocated memory operates 
on undefined state.  It doesn't matter for the result, though.  I guess 
the semantics of iosys_sys_clear() are not stellar.

> 
> Thanks for debugging this problem. It's uninitialized and some of the 
> internal helpers look at all planes, even if they are empty. I have a 
> patchset to fix that throughout the DRM modules. I'll post on Monday.

I have posted that patchset at [2]. If you have the time, I'd appreciate 
if you could give it a test run.

Best regards
Thomas

[1] 
https://elixir.bootlin.com/linux/v5.17.5/source/drivers/gpu/drm/drm_gem_framebuffer_helper.c#L348
[2] 
https://lore.kernel.org/dri-devel/20220509081602.474-1-tzimmermann@suse.de/T/#t

> 
> If we need a quick fix, we could do the zeroing everywhere.
> 
> Best regards
> Thomas
> 
>>
>> Noralf.
>>
>>>       void *vaddr, *buf;
>>>       size_t pitch, len;
>>>       int ret = 0;
>>> @@ -162,11 +162,11 @@ static int gud_prep_flush(struct gud_device 
>>> *gdrm, struct drm_framebuffer *fb,
>>>       if (len > gdrm->bulk_len)
>>>           return -E2BIG;
>>> -    ret = drm_gem_shmem_vmap(fb->obj[0], &map);
>>> +    ret = drm_gem_fb_vmap(fb, map);
>>>       if (ret)
>>>           return ret;
>>> -    vaddr = map.vaddr + fb->offsets[0];
>>> +    vaddr = map[0].vaddr + fb->offsets[0];
>>>       ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
>>>       if (ret)
>>> @@ -225,7 +225,7 @@ static int gud_prep_flush(struct gud_device 
>>> *gdrm, struct drm_framebuffer *fb,
>>>   end_cpu_access:
>>>       drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
>>>   vunmap:
>>> -    drm_gem_shmem_vunmap(fb->obj[0], &map);
>>> +    drm_gem_fb_vunmap(fb, map);
>>>       return ret;
>>>   }
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Ivo Totev

[-- Attachment #2: OpenPGP digital signature --]
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Re: [PATCH v3 4/5] drm/gud: Map framebuffer BOs with drm_gem_fb_vmap()

[Noralf Trønnes]

Den 09.05.2022 10.32, skrev Thomas Zimmermann:
> Hi Noralf
> 
> Am 06.05.22 um 16:11 schrieb Thomas Zimmermann:
>> Hi
>>
>> Am 06.05.22 um 16:01 schrieb Noralf Trønnes:
>>> Hi Thomas,
>>>
>>> I'm getting this on Ubuntu 22.04:
>>>
>>> [    0.000000] Linux version 5.15.0-27-generic (buildd@ubuntu) (gcc
>>> (Ubuntu 11.2.0-19ubuntu1) 11.2.0, GNU ld (GNU Binutils for Ubuntu) 2.38)
>>> #28-Ubuntu SMP Thu Apr 14 04:55:28 UTC 2022 (Ubuntu 5.15.0-27.28-generic
>>> 5.15.30)
>>>
>>> [    4.830866] usb 2-3.1: new high-speed USB device number 4 using
>>> xhci_hcd
>>> [    4.935546] usb 2-3.1: New USB device found, idVendor=1d50,
>>> idProduct=614d, bcdDevice= 1.00
>>> [    4.935553] usb 2-3.1: New USB device strings: Mfr=1, Product=2,
>>> SerialNumber=3
>>> [    4.935556] usb 2-3.1: Product: Raspberry Pi 4 Display Gadget
>>> [    4.935558] usb 2-3.1: Manufacturer: Raspberry Pi
>>> [    4.935560] usb 2-3.1: SerialNumber: 100000003b40d6c6
>>>
>>> [    7.497361] [drm] Initialized gud 1.0.0 20200422 for 2-3.1:1.0 on
>>> minor 0
>>>
>>> [    7.573048] gud 2-3.1:1.0: [drm] fb1: guddrmfb frame buffer device
>>>
>>> [    9.199402]
>>> ================================================================================
>>>
>>> [    9.199411] UBSAN: invalid-load in
>>> /build/linux-HMZHpV/linux-5.15.0/include/linux/dma-buf-map.h:224:9
>>> [    9.199416] load of value 226 is not a valid value for type '_Bool'
>>> [    9.199420] CPU: 0 PID: 113 Comm: kworker/0:2 Not tainted
>>> 5.15.0-27-generic #28-Ubuntu
>>> [    9.199424] Hardware name: Hewlett-Packard HP EliteBook 820 G1/1991,
>>> BIOS L71 Ver. 01.44 04/12/2018
>>> [    9.199427] Workqueue: events_long gud_flush_work [gud]
>>> [    9.199440] Call Trace:
>>> [    9.199443]  <TASK>
>>> [    9.199447]  show_stack+0x52/0x58
>>> [    9.199456]  dump_stack_lvl+0x4a/0x5f
>>> [    9.199464]  dump_stack+0x10/0x12
>>> [    9.199468]  ubsan_epilogue+0x9/0x45
>>> [    9.199473]  __ubsan_handle_load_invalid_value.cold+0x44/0x49
>>> [    9.199478]  drm_gem_fb_vmap.cold+0x10/0x3d [drm_kms_helper]
>>> [    9.199519]  gud_prep_flush+0xaa/0x410 [gud]
>>> [    9.199525]  ? check_preempt_curr+0x5d/0x70
>>> [    9.199533]  ? update_load_avg+0x82/0x620
>>> [    9.199540]  ? set_next_entity+0xb7/0x200
>>> [    9.199545]  gud_flush_work+0x1e0/0x430 [gud]
>>> [    9.199551]  ? psi_task_switch+0x1e7/0x220
>>> [    9.199557]  process_one_work+0x22b/0x3d0
>>> [    9.199564]  worker_thread+0x53/0x410
>>> [    9.199570]  ? process_one_work+0x3d0/0x3d0
>>> [    9.199575]  kthread+0x12a/0x150
>>> [    9.199579]  ? set_kthread_struct+0x50/0x50
>>> [    9.199584]  ret_from_fork+0x22/0x30
>>> [    9.199593]  </TASK>
>>> [    9.199595]
>>> ================================================================================
>>>
>>>
>>> [    9.199598]
>>> ================================================================================
>>>
>>> [    9.199600] UBSAN: invalid-load in
>>> /build/linux-HMZHpV/linux-5.15.0/include/linux/dma-buf-map.h:194:9
>>> [    9.199604] load of value 226 is not a valid value for type '_Bool'
>>> [    9.199606] CPU: 0 PID: 113 Comm: kworker/0:2 Not tainted
>>> 5.15.0-27-generic #28-Ubuntu
>>> [    9.199610] Hardware name: Hewlett-Packard HP EliteBook 820 G1/1991,
>>> BIOS L71 Ver. 01.44 04/12/2018
>>> [    9.199612] Workqueue: events_long gud_flush_work [gud]
>>> [    9.199618] Call Trace:
>>> [    9.199619]  <TASK>
>>> [    9.199621]  show_stack+0x52/0x58
>>> [    9.199627]  dump_stack_lvl+0x4a/0x5f
>>> [    9.199633]  dump_stack+0x10/0x12
>>> [    9.199637]  ubsan_epilogue+0x9/0x45
>>> [    9.199641]  __ubsan_handle_load_invalid_value.cold+0x44/0x49
>>> [    9.199646]  drm_gem_fb_vmap.cold+0x24/0x3d [drm_kms_helper]
>>> [    9.199675]  gud_prep_flush+0xaa/0x410 [gud]
>>> [    9.199682]  ? check_preempt_curr+0x5d/0x70
>>> [    9.199688]  ? update_load_avg+0x82/0x620
>>> [    9.199693]  ? update_load_avg+0x82/0x620
>>> [    9.199697]  gud_flush_work+0x1e0/0x430 [gud]
>>> [    9.199702]  ? psi_task_switch+0x1e7/0x220
>>> [    9.199706]  process_one_work+0x22b/0x3d0
>>> [    9.199713]  worker_thread+0x53/0x410
>>> [    9.199718]  ? process_one_work+0x3d0/0x3d0
>>> [    9.199723]  kthread+0x12a/0x150
>>> [    9.199728]  ? set_kthread_struct+0x50/0x50
>>> [    9.199732]  ret_from_fork+0x22/0x30
>>> [    9.199741]  </TASK>
>>> [    9.199743]
>>> ================================================================================
>>>
>>>
>>> It's the "if (map->is_iomem)" statement in dma_buf_map_clear() and
>>> dma_buf_map_is_null() that triggers this.
>>>
>>> I tried 5.18.0-rc5 and the problem is still present.
>>>
>>> UBSAN entries in the config:
>>>
>>> CONFIG_ARCH_HAS_UBSAN_SANITIZE_ALL=y
>>> CONFIG_UBSAN=y
>>> # CONFIG_UBSAN_TRAP is not set
>>> CONFIG_CC_HAS_UBSAN_BOUNDS=y
>>> CONFIG_UBSAN_BOUNDS=y
>>> CONFIG_UBSAN_ONLY_BOUNDS=y
>>> CONFIG_UBSAN_SHIFT=y
>>> # CONFIG_UBSAN_DIV_ZERO is not set
>>> CONFIG_UBSAN_BOOL=y
>>> CONFIG_UBSAN_ENUM=y
>>> # CONFIG_UBSAN_ALIGNMENT is not set
>>> CONFIG_UBSAN_SANITIZE_ALL=y
>>> # CONFIG_TEST_UBSAN is not set
>>>
>>> Continuing further down.
>>>
>>>
>>> Den 30.07.2021 20.35, skrev Thomas Zimmermann:
>>>> Abstract the framebuffer details by mapping its BOs with a call
>>>> to drm_gem_fb_vmap(). Unmap with drm_gem_fb_vunmap().
>>>>
>>>> The call to drm_gem_fb_vmap() ensures that all BOs are mapped
>>>> correctly. Gud still only supports single-plane formats.
>>>>
>>>> No functional changes.
>>>>
>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>> Acked-by: Noralf Trønnes <noralf@tronnes.org>
>>>> Acked-by: Sam Ravnborg <sam@ravnborg.org>
>>>> ---
>>>>   drivers/gpu/drm/gud/gud_pipe.c | 10 +++++-----
>>>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/gud/gud_pipe.c
>>>> b/drivers/gpu/drm/gud/gud_pipe.c
>>>> index 4d7a26b68a2e..7e009f562b30 100644
>>>> --- a/drivers/gpu/drm/gud/gud_pipe.c
>>>> +++ b/drivers/gpu/drm/gud/gud_pipe.c
>>>> @@ -14,8 +14,8 @@
>>>>   #include <drm/drm_format_helper.h>
>>>>   #include <drm/drm_fourcc.h>
>>>>   #include <drm/drm_framebuffer.h>
>>>> +#include <drm/drm_gem.h>
>>>>   #include <drm/drm_gem_framebuffer_helper.h>
>>>> -#include <drm/drm_gem_shmem_helper.h>
>>>>   #include <drm/drm_print.h>
>>>>   #include <drm/drm_rect.h>
>>>>   #include <drm/drm_simple_kms_helper.h>
>>>> @@ -152,7 +152,7 @@ static int gud_prep_flush(struct gud_device
>>>> *gdrm, struct drm_framebuffer *fb,
>>>>   {
>>>>       struct dma_buf_attachment *import_attach =
>>>> fb->obj[0]->import_attach;
>>>>       u8 compression = gdrm->compression;
>>>> -    struct dma_buf_map map;
>>>> +    struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];
>>>
>>> Zeroing map solves the problem:
>>>
>>>          struct iosys_map map[DRM_FORMAT_MAX_PLANES] = {};
>>>
>>> I don't understand the conditional clearing in
>>> dma_buf_map_clear/iosys_map_clear(), the doc says: Clears all fields to
>>> zero. If I zero the whole structure unconditionally this also keeps
>>> UBSAN happy.
> 
> iomap_sys_clear() assumes that the instance is already initialized.
> Hence, calling it at [1] with un-zeroed, stack-allocated memory operates
> on undefined state.  It doesn't matter for the result, though.  I guess
> the semantics of iosys_sys_clear() are not stellar.
> 

I did a quick look through the struct iosys_map users and found these
using a stack allocated variable that has not been initialized:

These call dma_buf_vmap() directly:
drm_gem_cma_prime_import_sg_table_vmap
igt_dmabuf_export_vmap
igt_dmabuf_import_ownership
igt_dmabuf_import
etnaviv_gem_prime_vmap_impl

Ends up calling dma_buf_vmap() if the bo is imported:
panfrost_perfcnt_enable_locked
lima_sched_build_error_task_list
tegra_bo_mmap
mipi_dbi_fb_dirty
mipi_dbi_buf_copy
gud_prep_flush

Ends up calling iosys_map_is_null() at least:
ast_cursor_plane_init

Ends up calling iosys_map_is_equal():
ast_cursor_plane_destroy

>>
>> Thanks for debugging this problem. It's uninitialized and some of the
>> internal helpers look at all planes, even if they are empty. I have a
>> patchset to fix that throughout the DRM modules. I'll post on Monday.
> 
> I have posted that patchset at [2]. If you have the time, I'd appreciate
> if you could give it a test run.
> 

I'll see if I can do that.

Noralf.

> Best regards
> Thomas
> 
> [1]
> https://elixir.bootlin.com/linux/v5.17.5/source/drivers/gpu/drm/drm_gem_framebuffer_helper.c#L348
> 
> [2]
> https://lore.kernel.org/dri-devel/20220509081602.474-1-tzimmermann@suse.de/T/#t
> 
> 
>>
>> If we need a quick fix, we could do the zeroing everywhere.
>>
>> Best regards
>> Thomas
>>
>>>
>>> Noralf.
>>>
>>>>       void *vaddr, *buf;
>>>>       size_t pitch, len;
>>>>       int ret = 0;
>>>> @@ -162,11 +162,11 @@ static int gud_prep_flush(struct gud_device
>>>> *gdrm, struct drm_framebuffer *fb,
>>>>       if (len > gdrm->bulk_len)
>>>>           return -E2BIG;
>>>> -    ret = drm_gem_shmem_vmap(fb->obj[0], &map);
>>>> +    ret = drm_gem_fb_vmap(fb, map);
>>>>       if (ret)
>>>>           return ret;
>>>> -    vaddr = map.vaddr + fb->offsets[0];
>>>> +    vaddr = map[0].vaddr + fb->offsets[0];
>>>>       ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
>>>>       if (ret)
>>>> @@ -225,7 +225,7 @@ static int gud_prep_flush(struct gud_device
>>>> *gdrm, struct drm_framebuffer *fb,
>>>>   end_cpu_access:
>>>>       drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
>>>>   vunmap:
>>>> -    drm_gem_shmem_vunmap(fb->obj[0], &map);
>>>> +    drm_gem_fb_vunmap(fb, map);
>>>>       return ret;
>>>>   }
>>
> 

[PATCH v3 5/5] drm/vkms: Map output framebuffer BOs with drm_gem_fb_vmap()

[Thomas Zimmermann]

Abstract the framebuffer details by mappings its BOs with a call
to drm_gem_fb_vmap(). Unmap with drm_gem_fb_vunamp().

Before, the output address with stored as raw pointer in the priv
field of struct drm_writeback_job. Introduce the new type
struct vkms_writeback_job, which holds the output mappings addresses
while the writeback job is active.

The patchset also cleans up some internal casting an setup of the
output addresses. No functional changes.

v3:
	* free instances of struct vkms_writeback_job on cleanup
	  or errors

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
---
 drivers/gpu/drm/vkms/vkms_composer.c  |  2 +-
 drivers/gpu/drm/vkms/vkms_drv.h       |  6 +++++-
 drivers/gpu/drm/vkms/vkms_writeback.c | 28 +++++++++++++++------------
 3 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index ead8fff81f30..49f109c3a2b3 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -257,7 +257,7 @@ void vkms_composer_worker(struct work_struct *work)
 		return;
 
 	if (wb_pending)
-		vaddr_out = crtc_state->active_writeback;
+		vaddr_out = crtc_state->active_writeback->map[0].vaddr;
 
 	ret = compose_active_planes(&vaddr_out, primary_composer,
 				    crtc_state);
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index 8c731b6dcba7..8bc9e3f52e1f 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -20,6 +20,10 @@
 #define XRES_MAX  8192
 #define YRES_MAX  8192
 
+struct vkms_writeback_job {
+	struct dma_buf_map map[DRM_FORMAT_MAX_PLANES];
+};
+
 struct vkms_composer {
 	struct drm_framebuffer fb;
 	struct drm_rect src, dst;
@@ -57,7 +61,7 @@ struct vkms_crtc_state {
 	int num_active_planes;
 	/* stack of active planes for crc computation, should be in z order */
 	struct vkms_plane_state **active_planes;
-	void *active_writeback;
+	struct vkms_writeback_job *active_writeback;
 
 	/* below four are protected by vkms_output.composer_lock */
 	bool crc_pending;
diff --git a/drivers/gpu/drm/vkms/vkms_writeback.c b/drivers/gpu/drm/vkms/vkms_writeback.c
index 0935686475a0..425b6c6b8cad 100644
--- a/drivers/gpu/drm/vkms/vkms_writeback.c
+++ b/drivers/gpu/drm/vkms/vkms_writeback.c
@@ -65,41 +65,45 @@ static int vkms_wb_connector_get_modes(struct drm_connector *connector)
 static int vkms_wb_prepare_job(struct drm_writeback_connector *wb_connector,
 			       struct drm_writeback_job *job)
 {
-	struct drm_gem_object *gem_obj;
-	struct dma_buf_map map;
+	struct vkms_writeback_job *vkmsjob;
 	int ret;
 
 	if (!job->fb)
 		return 0;
 
-	gem_obj = drm_gem_fb_get_obj(job->fb, 0);
-	ret = drm_gem_shmem_vmap(gem_obj, &map);
+	vkmsjob = kzalloc(sizeof(*vkmsjob), GFP_KERNEL);
+	if (!vkmsjob)
+		return -ENOMEM;
+
+	ret = drm_gem_fb_vmap(job->fb, vkmsjob->map);
 	if (ret) {
 		DRM_ERROR("vmap failed: %d\n", ret);
-		return ret;
+		goto err_kfree;
 	}
 
-	job->priv = map.vaddr;
+	job->priv = vkmsjob;
 
 	return 0;
+
+err_kfree:
+	kfree(vkmsjob);
+	return ret;
 }
 
 static void vkms_wb_cleanup_job(struct drm_writeback_connector *connector,
 				struct drm_writeback_job *job)
 {
-	struct drm_gem_object *gem_obj;
+	struct vkms_writeback_job *vkmsjob = job->priv;
 	struct vkms_device *vkmsdev;
-	struct dma_buf_map map;
 
 	if (!job->fb)
 		return;
 
-	gem_obj = drm_gem_fb_get_obj(job->fb, 0);
-	dma_buf_map_set_vaddr(&map, job->priv);
-	drm_gem_shmem_vunmap(gem_obj, &map);
+	drm_gem_fb_vunmap(job->fb, vkmsjob->map);
 
-	vkmsdev = drm_device_to_vkms_device(gem_obj->dev);
+	vkmsdev = drm_device_to_vkms_device(job->fb->dev);
 	vkms_set_composer(&vkmsdev->output, false);
+	kfree(vkmsjob);
 }
 
 static void vkms_wb_atomic_commit(struct drm_connector *conn,
-- 
2.32.0