Message-ID: <sel7vspg4xzjb3wrp2zn5m5yjpzu6ajxxhdyll5u5twqojlmbz@lyz4lv3q67ye>
Date: Thu, 17 Apr 2025 15:46:12 +0100
From: Adrián Larumbe <adrian.larumbe@...labora.com>
To: Steven Price <steven.price@....com>
Cc: Boris Brezillon <boris.brezillon@...labora.com>, 
	Liviu Dudau <liviu.dudau@....com>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Sumit Semwal <sumit.semwal@...aro.org>, Christian König <christian.koenig@....com>, 
	kernel@...labora.com, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	linux-media@...r.kernel.org, linaro-mm-sig@...ts.linaro.org
Subject: Re: [PATCH v8 4/4] drm/panthor: show device-wide list of DRM GEM
 objects over DebugFS

Hi Steve,

On 17.04.2025 15:25, Steven Price wrote:
> On 15/04/2025 20:15, Adrián Larumbe wrote:
> > Add a device DebugFS file that displays a complete list of all the DRM
> > GEM objects that are exposed to UM through a DRM handle.
> >
> > Since leaking object identifiers that might belong to a different NS is
> > inadmissible, this functionality is only made available in debug builds
> > with DEBUGFS support enabled.
> >
> > File format is that of a table, with each entry displaying a variety of
> > fields with information about each GEM object.
> >
> > Each GEM object entry in the file displays the following information
> > fields: Client PID, BO's global name, reference count, BO virtual size,
> > BO resize size, VM address in its DRM-managed range, BO label and a GEM
> > state flags.
> >
> > There's also a usage flags field for the type of BO, which tells us
> > whether it's a kernel BO and/or mapped onto the FW's address space.
> >
> > Signed-off-by: Adrián Larumbe <adrian.larumbe@...labora.com>
> > Reviewed-by: Liviu Dudau <liviu.dudau@....com>
> > Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>
>
> Reviewed-by: Steven Price <steven.price@....com>
>
> Although I feel I have to point out the table output is much wider than
> it needs to be. I'd personally like it if some of the columns were made
> narrower. But I guess the idea is this is going to be read by a script
> anyway.

In a previous revision, table format was a lot tighter, but Boris
pointed out the number of BO flags might increase in the future, so in
order to save ourselves some headache form having to reformat
everything, it was best to give those fields some extra padding even if
that means BO label spans over the usual screen width.

> Thanks,
> Steve
>
> > ---
> >  drivers/gpu/drm/panthor/panthor_device.c |   5 +
> >  drivers/gpu/drm/panthor/panthor_device.h |  11 ++
> >  drivers/gpu/drm/panthor/panthor_drv.c    |  26 ++++
> >  drivers/gpu/drm/panthor/panthor_gem.c    | 182 +++++++++++++++++++++++
> >  drivers/gpu/drm/panthor/panthor_gem.h    |  59 ++++++++
> >  5 files changed, 283 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> > index a9da1d1eeb70..b776e1a2e4f3 100644
> > --- a/drivers/gpu/drm/panthor/panthor_device.c
> > +++ b/drivers/gpu/drm/panthor/panthor_device.c
> > @@ -184,6 +184,11 @@ int panthor_device_init(struct panthor_device *ptdev)
> >  	if (ret)
> >  		return ret;
> >
> > +#ifdef CONFIG_DEBUG_FS
> > +	drmm_mutex_init(&ptdev->base, &ptdev->gems.lock);
> > +	INIT_LIST_HEAD(&ptdev->gems.node);
> > +#endif
> > +
> >  	atomic_set(&ptdev->pm.state, PANTHOR_DEVICE_PM_STATE_SUSPENDED);
> >  	p = alloc_page(GFP_KERNEL | __GFP_ZERO);
> >  	if (!p)
> > diff --git a/drivers/gpu/drm/panthor/panthor_device.h b/drivers/gpu/drm/panthor/panthor_device.h
> > index da6574021664..86206a961b38 100644
> > --- a/drivers/gpu/drm/panthor/panthor_device.h
> > +++ b/drivers/gpu/drm/panthor/panthor_device.h
> > @@ -205,6 +205,17 @@ struct panthor_device {
> >
> >  	/** @fast_rate: Maximum device clock frequency. Set by DVFS */
> >  	unsigned long fast_rate;
> > +
> > +#ifdef CONFIG_DEBUG_FS
> > +	/** @gems: Device-wide list of GEM objects owned by at least one file. */
> > +	struct {
> > +		/** @gems.lock: Protects the device-wide list of GEM objects. */
> > +		struct mutex lock;
> > +
> > +		/** @node: Used to keep track of all the device's DRM objects */
> > +		struct list_head node;
> > +	} gems;
> > +#endif
> >  };
> >
> >  struct panthor_gpu_usage {
> > diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c
> > index 7660627cafa1..13f0b045c5fd 100644
> > --- a/drivers/gpu/drm/panthor/panthor_drv.c
> > +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> > @@ -1557,9 +1557,35 @@ static const struct file_operations panthor_drm_driver_fops = {
> >  };
> >
> >  #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 panthor_device *ptdev = container_of(dev, struct panthor_device, base);
> > +
> > +	panthor_gem_debugfs_print_bos(ptdev, 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 panthor_debugfs_init(struct drm_minor *minor)
> >  {
> >  	panthor_mmu_debugfs_init(minor);
> > +	panthor_gems_debugfs_init(minor);
> >  }
> >  #endif
> >
> > diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> > index 3f4ab5a2f2ae..1e3409c05891 100644
> > --- a/drivers/gpu/drm/panthor/panthor_gem.c
> > +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> > @@ -11,14 +11,51 @@
> >  #include <drm/panthor_drm.h>
> >
> >  #include "panthor_device.h"
> > +#include "panthor_fw.h"
> >  #include "panthor_gem.h"
> >  #include "panthor_mmu.h"
> >
> > +#ifdef CONFIG_DEBUG_FS
> > +static void panthor_gem_debugfs_bo_add(struct panthor_device *ptdev,
> > +				       struct panthor_gem_object *bo)
> > +{
> > +	INIT_LIST_HEAD(&bo->debugfs.node);
> > +
> > +	bo->debugfs.creator.tgid = current->group_leader->pid;
> > +	get_task_comm(bo->debugfs.creator.process_name, current->group_leader);
> > +
> > +	mutex_lock(&ptdev->gems.lock);
> > +	list_add_tail(&bo->debugfs.node, &ptdev->gems.node);
> > +	mutex_unlock(&ptdev->gems.lock);
> > +}
> > +
> > +static void panthor_gem_debugfs_bo_rm(struct panthor_gem_object *bo)
> > +{
> > +	struct panthor_device *ptdev = container_of(bo->base.base.dev,
> > +						    struct panthor_device, base);
> > +
> > +	if (list_empty(&bo->debugfs.node))
> > +		return;
> > +
> > +	mutex_lock(&ptdev->gems.lock);
> > +	list_del_init(&bo->debugfs.node);
> > +	mutex_unlock(&ptdev->gems.lock);
> > +}
> > +
> > +#else
> > +static void panthor_gem_debugfs_bo_add(struct panthor_device *ptdev,
> > +				       struct panthor_gem_object *bo)
> > +{}
> > +static void panthor_gem_debugfs_bo_rm(struct panthor_gem_object *bo) {}
> > +#endif
> > +
> >  static void panthor_gem_free_object(struct drm_gem_object *obj)
> >  {
> >  	struct panthor_gem_object *bo = to_panthor_bo(obj);
> >  	struct drm_gem_object *vm_root_gem = bo->exclusive_vm_root_gem;
> >
> > +	panthor_gem_debugfs_bo_rm(bo);
> > +
> >  	/*
> >  	 * Label might have been allocated with kstrdup_const(),
> >  	 * we need to take that into account when freeing the memory
> > @@ -88,6 +125,7 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
> >  	struct drm_gem_shmem_object *obj;
> >  	struct panthor_kernel_bo *kbo;
> >  	struct panthor_gem_object *bo;
> > +	u32 debug_flags = PANTHOR_DEBUGFS_GEM_USAGE_FLAG_KERNEL;
> >  	int ret;
> >
> >  	if (drm_WARN_ON(&ptdev->base, !vm))
> > @@ -107,7 +145,11 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
> >  	kbo->obj = &obj->base;
> >  	bo->flags = bo_flags;
> >
> > +	if (vm == panthor_fw_vm(ptdev))
> > +		debug_flags |= PANTHOR_DEBUGFS_GEM_USAGE_FLAG_FW_MAPPED;
> > +
> >  	panthor_gem_kernel_bo_set_label(kbo, name);
> > +	panthor_gem_debugfs_set_usage_flags(to_panthor_bo(kbo->obj), debug_flags);
> >
> >  	/* The system and GPU MMU page size might differ, which becomes a
> >  	 * problem for FW sections that need to be mapped at explicit address
> > @@ -210,6 +252,8 @@ struct drm_gem_object *panthor_gem_create_object(struct drm_device *ddev, size_t
> >  	drm_gem_gpuva_set_lock(&obj->base.base, &obj->gpuva_list_lock);
> >  	mutex_init(&obj->label.lock);
> >
> > +	panthor_gem_debugfs_bo_add(ptdev, obj);
> > +
> >  	return &obj->base.base;
> >  }
> >
> > @@ -258,6 +302,12 @@ panthor_gem_create_with_handle(struct drm_file *file,
> >  	/* drop reference from allocate - handle holds it now. */
> >  	drm_gem_object_put(&shmem->base);
> >
> > +	/*
> > +	 * No explicit flags are needed in the call below, since the
> > +	 * function internally sets the INITIALIZED bit for us.
> > +	 */
> > +	panthor_gem_debugfs_set_usage_flags(bo, 0);
> > +
> >  	return ret;
> >  }
> >
> > @@ -296,3 +346,135 @@ panthor_gem_kernel_bo_set_label(struct panthor_kernel_bo *bo, const char *label)
> >
> >  	panthor_gem_bo_set_label(bo->obj, str);
> >  }
> > +
> > +#ifdef CONFIG_DEBUG_FS
> > +static void
> > +panthor_gem_debugfs_format_flags(char flags_str[], int flags_len,
> > +				 const char * const names[], u32 name_count,
> > +				 u32 flags)
> > +{
> > +	bool first = true;
> > +	int offset = 0;
> > +
> > +#define ACC_FLAGS(...) \
> > +	({ \
> > +		offset += snprintf(flags_str + offset, flags_len - offset, ##__VA_ARGS__); \
> > +		if (offset == flags_len) \
> > +			return; \
> > +	})
> > +
> > +	ACC_FLAGS("%c", '(');
> > +
> > +	if (!flags)
> > +		ACC_FLAGS("%s", "none");
> > +
> > +	while (flags) {
> > +		u32 bit = fls(flags) - 1;
> > +		u32 idx = bit + 1;
> > +
> > +		if (!first)
> > +			ACC_FLAGS("%s", ",");
> > +
> > +		if (idx < name_count && names[idx])
> > +			ACC_FLAGS("%s", names[idx]);
> > +
> > +		first = false;
> > +		flags &= ~BIT(bit);
> > +	}
> > +
> > +	ACC_FLAGS("%c", ')');
> > +
> > +#undef ACC_FLAGS
> > +}
> > +
> > +struct gem_size_totals {
> > +	size_t size;
> > +	size_t resident;
> > +	size_t reclaimable;
> > +};
> > +
> > +static void panthor_gem_debugfs_bo_print(struct panthor_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;
> > +	char gem_state_str[64] = {};
> > +	char gem_usage_str[64] = {};
> > +	u32 gem_usage_flags = bo->debugfs.flags & (u32)~PANTHOR_DEBUGFS_GEM_USAGE_FLAG_INITIALIZED;
> > +	u32 gem_state_flags = 0;
> > +
> > +	static const char * const gem_state_flags_names[] = {
> > +		[PANTHOR_DEBUGFS_GEM_STATE_FLAG_IMPORTED] = "imported",
> > +		[PANTHOR_DEBUGFS_GEM_STATE_FLAG_EXPORTED] = "exported",
> > +	};
> > +
> > +	static const char * const gem_usage_flags_names[] = {
> > +		[PANTHOR_DEBUGFS_GEM_USAGE_FLAG_KERNEL] = "kernel",
> > +		[PANTHOR_DEBUGFS_GEM_USAGE_FLAG_FW_MAPPED] = "fw-mapped",
> > +	};
> > +
> > +	/* Skip BOs being destroyed. */
> > +	if (!refcount)
> > +		return;
> > +
> > +	resident_size = bo->base.pages != NULL ? 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%-16zd%-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 != NULL)
> > +		gem_state_flags |= PANTHOR_DEBUGFS_GEM_STATE_FLAG_IMPORTED;
> > +	if (bo->base.base.dma_buf != NULL)
> > +		gem_state_flags |= PANTHOR_DEBUGFS_GEM_STATE_FLAG_EXPORTED;
> > +
> > +	panthor_gem_debugfs_format_flags(gem_state_str, sizeof(gem_state_str),
> > +					 gem_state_flags_names, ARRAY_SIZE(gem_state_flags_names),
> > +					 gem_state_flags);
> > +	panthor_gem_debugfs_format_flags(gem_usage_str, sizeof(gem_usage_str),
> > +					 gem_usage_flags_names, ARRAY_SIZE(gem_usage_flags_names),
> > +					 gem_usage_flags);
> > +
> > +	seq_printf(m, "%-64s%-64s", gem_state_str, gem_usage_str);
> > +
> > +	scoped_guard(mutex, &bo->label.lock) {
> > +		seq_printf(m, "%s", bo->label.str ? : "");
> > +	}
> > +
> > +	seq_puts(m, "\n");
> > +
> > +	totals->size += bo->base.base.size;
> > +	totals->resident += resident_size;
> > +	if (bo->base.madv > 0)
> > +		totals->reclaimable += resident_size;
> > +}
> > +
> > +void panthor_gem_debugfs_print_bos(struct panthor_device *ptdev,
> > +				   struct seq_file *m)
> > +{
> > +	struct gem_size_totals totals = {0};
> > +	struct panthor_gem_object *bo;
> > +
> > +	seq_puts(m, "created-by                      global-name     refcount        size            resident-size   file-offset     state                                                           usage                                                           label\n");
> > +	seq_puts(m, "-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------\n");
> > +
> > +	scoped_guard(mutex, &ptdev->gems.lock) {
> > +		list_for_each_entry(bo, &ptdev->gems.node, debugfs.node) {
> > +			if (bo->debugfs.flags & PANTHOR_DEBUGFS_GEM_USAGE_FLAG_INITIALIZED)
> > +				panthor_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
> > diff --git a/drivers/gpu/drm/panthor/panthor_gem.h b/drivers/gpu/drm/panthor/panthor_gem.h
> > index 3c09af568e47..94b244f0540e 100644
> > --- a/drivers/gpu/drm/panthor/panthor_gem.h
> > +++ b/drivers/gpu/drm/panthor/panthor_gem.h
> > @@ -15,6 +15,48 @@ struct panthor_vm;
> >
> >  #define PANTHOR_BO_LABEL_MAXLEN	4096
> >
> > +enum panthor_debugfs_gem_state_flags {
> > +	/** @PANTHOR_DEBUGFS_GEM_STATE_FLAG_IMPORTED: GEM BO is PRIME imported. */
> > +	PANTHOR_DEBUGFS_GEM_STATE_FLAG_IMPORTED = BIT(0),
> > +
> > +	/** @PANTHOR_DEBUGFS_GEM_STATE_FLAG_EXPORTED: GEM BO is PRIME exported. */
> > +	PANTHOR_DEBUGFS_GEM_STATE_FLAG_EXPORTED = BIT(1),
> > +};
> > +
> > +enum panthor_debugfs_gem_usage_flags {
> > +	/** @PANTHOR_DEBUGFS_GEM_USAGE_FLAG_KERNEL: BO is for kernel use only. */
> > +	PANTHOR_DEBUGFS_GEM_USAGE_FLAG_KERNEL = BIT(0),
> > +
> > +	/** @PANTHOR_DEBUGFS_GEM_USAGE_FLAG_FW_MAPPED: BO is mapped on the FW VM. */
> > +	PANTHOR_DEBUGFS_GEM_USAGE_FLAG_FW_MAPPED = BIT(1),
> > +
> > +	/** @PANTHOR_DEBUGFS_GEM_USAGE_FLAG_INITIALIZED: BO is ready for DebugFS display. */
> > +	PANTHOR_DEBUGFS_GEM_USAGE_FLAG_INITIALIZED = BIT(31),
> > +};
> > +
> > +/**
> > + * struct panthor_gem_debugfs - GEM object's DebugFS list information
> > + */
> > +struct panthor_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;
> > +
> > +	/** @flags: Combination of panthor_debugfs_gem_usage_flags flags */
> > +	u32 flags;
> > +};
> > +
> >  /**
> >   * struct panthor_gem_object - Driver specific GEM object.
> >   */
> > @@ -62,6 +104,10 @@ struct panthor_gem_object {
> >  		/** @lock.str: Protects access to the @label.str field. */
> >  		struct mutex lock;
> >  	} label;
> > +
> > +#ifdef CONFIG_DEBUG_FS
> > +	struct panthor_gem_debugfs debugfs;
> > +#endif
> >  };
> >
> >  /**
> > @@ -157,4 +203,17 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
> >
> >  void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo);
> >
> > +#ifdef CONFIG_DEBUG_FS
> > +void panthor_gem_debugfs_print_bos(struct panthor_device *pfdev,
> > +				   struct seq_file *m);
> > +static inline void
> > +panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo, u32 usage_flags)
> > +{
> > +	bo->debugfs.flags = usage_flags | PANTHOR_DEBUGFS_GEM_USAGE_FLAG_INITIALIZED;
> > +}
> > +
> > +#else
> > +void panthor_gem_debugfs_set_usage_flags(struct panthor_gem_object *bo, u32 usage_flags) {};
> > +#endif
> > +
> >  #endif /* __PANTHOR_GEM_H__ */

Adrian Larumbe

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