drm/panfrost: show device-wide list of DRM GEM objects over DebugFS

This change is essentially a Panfrost port of commit a3707f53eb
("drm/panthor: show device-wide list of DRM GEM objects over DebugFS").

The DebugFS file is almost the same as in Panthor, minus the GEM object
usage flags, since Panfrost has no kernel-only BO's.

Two additional GEM state flags which are displayed but aren't relevant
to Panthor are 'Purged' and 'Purgeable', since Panfrost implements an
explicit shrinker and a madvise ioctl to flag objects as reclaimable.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://lore.kernel.org/r/20250520174634.353267-5-adrian.larumbe@collabora.com

drivers/gpu/drm/panfrost/panfrost_device.c

@@ -209,6 +209,11 @@ int panfrost_device_init(struct panfrost_device *pfdev)
 
 	spin_lock_init(&pfdev->cycle_counter.lock);
 
+#ifdef CONFIG_DEBUG_FS
+	mutex_init(&pfdev->debugfs.gems_lock);
+	INIT_LIST_HEAD(&pfdev->debugfs.gems_list);
+#endif
+
 	err = panfrost_pm_domain_init(pfdev);
 	if (err)
 		return err;

drivers/gpu/drm/panfrost/panfrost_device.h

@@ -111,6 +111,17 @@ struct panfrost_compatible {
 	u8 gpu_quirks;
 };
 
+/**
+ * struct panfrost_device_debugfs - Device-wide DebugFS tracking structures
+ */
+struct panfrost_device_debugfs {
+	/** @gems_list: Device-wide list of GEM objects owned by at least one file. */
+	struct list_head gems_list;
+
+	/** @gems_lock: Serializes access to the device-wide list of GEM objects. */
+	struct mutex gems_lock;
+};
+
 struct panfrost_device {
 	struct device *dev;
 	struct drm_device *ddev;
@@ -164,6 +175,10 @@ struct panfrost_device {
 		atomic_t use_count;
 		spinlock_t lock;
 	} cycle_counter;
+
+#ifdef CONFIG_DEBUG_FS
+	struct panfrost_device_debugfs debugfs;
+#endif
 };
 
 struct panfrost_mmu {

drivers/gpu/drm/panfrost/panfrost_drv.c

@@ -13,6 +13,7 @@
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <drm/panfrost_drm.h>
+#include <drm/drm_debugfs.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_ioctl.h>
 #include <drm/drm_syncobj.h>
@@ -659,6 +660,37 @@ static const struct file_operations panfrost_drm_driver_fops = {
 	.show_fdinfo = drm_show_fdinfo,
 };
 
+#ifdef CONFIG_DEBUG_FS
+static int panthor_gems_show(struct seq_file *m, void *data)
+{
+	struct drm_info_node *node = m->private;
+	struct drm_device *dev = node->minor->dev;
+	struct panfrost_device *pfdev = dev->dev_private;
+
+	panfrost_gem_debugfs_print_bos(pfdev, m);
+
+	return 0;
+}
+
+static struct drm_info_list panthor_debugfs_list[] = {
+	{"gems", panthor_gems_show, 0, NULL},
+};
+
+static int panthor_gems_debugfs_init(struct drm_minor *minor)
+{
+	drm_debugfs_create_files(panthor_debugfs_list,
+				 ARRAY_SIZE(panthor_debugfs_list),
+				 minor->debugfs_root, minor);
+
+	return 0;
+}
+
+static void panfrost_debugfs_init(struct drm_minor *minor)
+{
+	panthor_gems_debugfs_init(minor);
+}
+#endif
+
 /*
  * Panfrost driver version:
  * - 1.0 - initial interface
@@ -683,6 +715,9 @@ static const struct drm_driver panfrost_drm_driver = {
 
 	.gem_create_object	= panfrost_gem_create_object,
 	.gem_prime_import_sg_table = panfrost_gem_prime_import_sg_table,
+#ifdef CONFIG_DEBUG_FS
+	.debugfs_init = panfrost_debugfs_init,
+#endif
 };
 
 static int panfrost_probe(struct platform_device *pdev)

drivers/gpu/drm/panfrost/panfrost_gem.c

@@ -12,6 +12,36 @@
 #include "panfrost_gem.h"
 #include "panfrost_mmu.h"
 
+#ifdef CONFIG_DEBUG_FS
+static void panfrost_gem_debugfs_bo_add(struct panfrost_device *pfdev,
+					struct panfrost_gem_object *bo)
+{
+	bo->debugfs.creator.tgid = current->group_leader->pid;
+	get_task_comm(bo->debugfs.creator.process_name, current->group_leader);
+
+	mutex_lock(&pfdev->debugfs.gems_lock);
+	list_add_tail(&bo->debugfs.node, &pfdev->debugfs.gems_list);
+	mutex_unlock(&pfdev->debugfs.gems_lock);
+}
+
+static void panfrost_gem_debugfs_bo_rm(struct panfrost_gem_object *bo)
+{
+	struct panfrost_device *pfdev = bo->base.base.dev->dev_private;
+
+	if (list_empty(&bo->debugfs.node))
+		return;
+
+	mutex_lock(&pfdev->debugfs.gems_lock);
+	list_del_init(&bo->debugfs.node);
+	mutex_unlock(&pfdev->debugfs.gems_lock);
+}
+#else
+static void panfrost_gem_debugfs_bo_add(struct panfrost_device *pfdev,
+					struct panfrost_gem_object *bo)
+{}
+static void panfrost_gem_debugfs_bo_rm(struct panfrost_gem_object *bo) {}
+#endif
+
 /* Called DRM core on the last userspace/kernel unreference of the
  * BO.
  */
@@ -37,6 +67,7 @@ static void panfrost_gem_free_object(struct drm_gem_object *obj)
 	WARN_ON_ONCE(!list_empty(&bo->mappings.list));
 
 	kfree_const(bo->label.str);
+	panfrost_gem_debugfs_bo_rm(bo);
 	mutex_destroy(&bo->label.lock);
 
 	if (bo->sgts) {
@@ -266,6 +297,8 @@ struct drm_gem_object *panfrost_gem_create_object(struct drm_device *dev, size_t
 	obj->base.map_wc = !pfdev->coherent;
 	mutex_init(&obj->label.lock);
 
+	panfrost_gem_debugfs_bo_add(pfdev, obj);
+
 	return &obj->base.base;
 }
 
@@ -354,3 +387,104 @@ panfrost_gem_internal_set_label(struct drm_gem_object *obj, const char *label)
 
 	panfrost_gem_set_label(obj, str);
 }
+
+#ifdef CONFIG_DEBUG_FS
+struct gem_size_totals {
+	size_t size;
+	size_t resident;
+	size_t reclaimable;
+};
+
+struct flag_def {
+	u32 flag;
+	const char *name;
+};
+
+static void panfrost_gem_debugfs_print_flag_names(struct seq_file *m)
+{
+	int len;
+	int i;
+
+	static const struct flag_def gem_state_flags_names[] = {
+		{PANFROST_DEBUGFS_GEM_STATE_FLAG_IMPORTED, "imported"},
+		{PANFROST_DEBUGFS_GEM_STATE_FLAG_EXPORTED, "exported"},
+		{PANFROST_DEBUGFS_GEM_STATE_FLAG_PURGED, "purged"},
+		{PANFROST_DEBUGFS_GEM_STATE_FLAG_PURGEABLE, "purgeable"},
+	};
+
+	seq_puts(m, "GEM state flags: ");
+	for (i = 0, len = ARRAY_SIZE(gem_state_flags_names); i < len; i++) {
+		seq_printf(m, "%s (0x%x)%s", gem_state_flags_names[i].name,
+			   gem_state_flags_names[i].flag, (i < len - 1) ? ", " : "\n\n");
+	}
+}
+
+static void panfrost_gem_debugfs_bo_print(struct panfrost_gem_object *bo,
+					  struct seq_file *m,
+					  struct gem_size_totals *totals)
+{
+	unsigned int refcount = kref_read(&bo->base.base.refcount);
+	char creator_info[32] = {};
+	size_t resident_size;
+	u32 gem_state_flags = 0;
+
+	/* Skip BOs being destroyed. */
+	if (!refcount)
+		return;
+
+	resident_size = bo->base.pages ? bo->base.base.size : 0;
+
+	snprintf(creator_info, sizeof(creator_info),
+		 "%s/%d", bo->debugfs.creator.process_name, bo->debugfs.creator.tgid);
+	seq_printf(m, "%-32s%-16d%-16d%-16zd%-16zd0x%-16lx",
+		   creator_info,
+		   bo->base.base.name,
+		   refcount,
+		   bo->base.base.size,
+		   resident_size,
+		   drm_vma_node_start(&bo->base.base.vma_node));
+
+	if (bo->base.base.import_attach)
+		gem_state_flags |= PANFROST_DEBUGFS_GEM_STATE_FLAG_IMPORTED;
+	if (bo->base.base.dma_buf)
+		gem_state_flags |= PANFROST_DEBUGFS_GEM_STATE_FLAG_EXPORTED;
+
+	if (bo->base.madv < 0)
+		gem_state_flags |= PANFROST_DEBUGFS_GEM_STATE_FLAG_PURGED;
+	else if (bo->base.madv > 0)
+		gem_state_flags |= PANFROST_DEBUGFS_GEM_STATE_FLAG_PURGEABLE;
+
+	seq_printf(m, "0x%-10x", gem_state_flags);
+
+	scoped_guard(mutex, &bo->label.lock) {
+		seq_printf(m, "%s\n", bo->label.str ? : "");
+	}
+
+	totals->size += bo->base.base.size;
+	totals->resident += resident_size;
+	if (bo->base.madv > 0)
+		totals->reclaimable += resident_size;
+}
+
+void panfrost_gem_debugfs_print_bos(struct panfrost_device *pfdev,
+				    struct seq_file *m)
+{
+	struct gem_size_totals totals = {0};
+	struct panfrost_gem_object *bo;
+
+	panfrost_gem_debugfs_print_flag_names(m);
+
+	seq_puts(m, "created-by                      global-name     refcount        size            resident-size   file-offset       state       label\n");
+	seq_puts(m, "-----------------------------------------------------------------------------------------------------------------------------------\n");
+
+	scoped_guard(mutex, &pfdev->debugfs.gems_lock) {
+		list_for_each_entry(bo, &pfdev->debugfs.gems_list, debugfs.node) {
+			panfrost_gem_debugfs_bo_print(bo, m, &totals);
+		}
+	}
+
+	seq_puts(m, "===================================================================================================================================\n");
+	seq_printf(m, "Total size: %zd, Total resident: %zd, Total reclaimable: %zd\n",
+		   totals.size, totals.resident, totals.reclaimable);
+}
+#endif

drivers/gpu/drm/panfrost/panfrost_gem.h

@@ -8,9 +8,47 @@
 #include <drm/drm_mm.h>
 
 struct panfrost_mmu;
+struct panfrost_device;
 
 #define PANFROST_BO_LABEL_MAXLEN	4096
 
+enum panfrost_debugfs_gem_state_flags {
+	/** @PANFROST_DEBUGFS_GEM_STATE_FLAG_IMPORTED: GEM BO is PRIME imported. */
+	PANFROST_DEBUGFS_GEM_STATE_FLAG_IMPORTED = BIT(0),
+
+	/** @PANFROST_DEBUGFS_GEM_STATE_FLAG_EXPORTED: GEM BO is PRIME exported. */
+	PANFROST_DEBUGFS_GEM_STATE_FLAG_EXPORTED = BIT(1),
+
+	/** @PANFROST_DEBUGFS_GEM_STATE_FLAG_PURGED: GEM BO was reclaimed by the shrinker. */
+	PANFROST_DEBUGFS_GEM_STATE_FLAG_PURGED = BIT(2),
+
+	/**
+	 * @PANFROST_DEBUGFS_GEM_STATE_FLAG_PURGEABLE: GEM BO pages were marked as no longer
+	 * needed by UM and can be reclaimed by the shrinker.
+	 */
+	PANFROST_DEBUGFS_GEM_STATE_FLAG_PURGEABLE = BIT(3),
+};
+
+/**
+ * struct panfrost_gem_debugfs - GEM object's DebugFS list information
+ */
+struct panfrost_gem_debugfs {
+	/**
+	 * @node: Node used to insert the object in the device-wide list of
+	 * GEM objects, to display information about it through a DebugFS file.
+	 */
+	struct list_head node;
+
+	/** @creator: Information about the UM process which created the GEM. */
+	struct {
+		/** @creator.process_name: Group leader name in owning thread's process */
+		char process_name[TASK_COMM_LEN];
+
+		/** @creator.tgid: PID of the thread's group leader within its process */
+		pid_t tgid;
+	} creator;
+};
+
 struct panfrost_gem_object {
 	struct drm_gem_shmem_object base;
 	struct sg_table *sgts;
@@ -59,6 +97,10 @@ struct panfrost_gem_object {
 
 	bool noexec		:1;
 	bool is_heap		:1;
+
+#ifdef CONFIG_DEBUG_FS
+	struct panfrost_gem_debugfs debugfs;
+#endif
 };
 
 struct panfrost_gem_mapping {
@@ -108,4 +150,9 @@ void panfrost_gem_shrinker_cleanup(struct drm_device *dev);
 void panfrost_gem_set_label(struct drm_gem_object *obj, const char *label);
 void panfrost_gem_internal_set_label(struct drm_gem_object *obj, const char *label);
 
+#ifdef CONFIG_DEBUG_FS
+void panfrost_gem_debugfs_print_bos(struct panfrost_device *pfdev,
+				    struct seq_file *m);
+#endif
+
 #endif /* __PANFROST_GEM_H__ */