Re: [PATCH v3 3/4] drm/panthor: show device-wide list of DRM GEM objects over DebugFS

From: Boris Brezillon
Date: Fri Mar 28 2025 - 10:35:14 EST

Next message: Mukesh Kumar Savaliya: "Re: [PATCH v2 2/3] i3c: master: Add Qualcomm I3C controller driver"
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In reply to: Adrián Larumbe: "[PATCH v3 3/4] drm/panthor: show device-wide list of DRM GEM objects over DebugFS"
Next in thread: Adrián Larumbe: "[PATCH v3 2/4] drm/panthor: Add driver IOCTL for setting BO labels"
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On Thu, 27 Mar 2025 14:08:36 +0000
Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx> 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 flag
> bitmask.
>
> Signed-off-by: Adrián Larumbe <adrian.larumbe@xxxxxxxxxxxxx>
> ---
> 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 | 130 +++++++++++++++++++++++
> drivers/gpu/drm/panthor/panthor_gem.h | 29 +++++
> 5 files changed, 201 insertions(+)
>
> diff --git a/drivers/gpu/drm/panthor/panthor_device.c b/drivers/gpu/drm/panthor/panthor_device.c
> index a9da1d1eeb70..bae1a74d7111 100644
> --- a/drivers/gpu/drm/panthor/panthor_device.c
> +++ b/drivers/gpu/drm/panthor/panthor_device.c
> @@ -263,6 +263,11 @@ int panthor_device_init(struct panthor_device *ptdev)
> pm_runtime_set_autosuspend_delay(ptdev->base.dev, 50);
> pm_runtime_use_autosuspend(ptdev->base.dev);
>
> +#ifdef CONFIG_DEBUG_FS
> + drmm_mutex_init(&ptdev->base, &ptdev->gems.lock);
> + INIT_LIST_HEAD(&ptdev->gems.node);
> +#endif
> +
> ret = drm_dev_register(&ptdev->base, 0);
> if (ret)
> goto err_disable_autosuspend;
> 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 488d17466494..0ba68a51b4ef 100644
> --- a/drivers/gpu/drm/panthor/panthor_drv.c
> +++ b/drivers/gpu/drm/panthor/panthor_drv.c
> @@ -1534,9 +1534,35 @@ 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 7d017f9d1d52..fbf560920194 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.c
> +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> @@ -2,6 +2,7 @@
> /* Copyright 2019 Linaro, Ltd, Rob Herring <robh@xxxxxxxxxx> */
> /* Copyright 2023 Collabora ltd. */
>
> +#include <linux/cleanup.h>
> #include <linux/dma-buf.h>
> #include <linux/dma-mapping.h>
> #include <linux/err.h>
> @@ -13,11 +14,49 @@
> #include "panthor_gem.h"
> #include "panthor_mmu.h"
>
> +#ifdef CONFIG_DEBUG_FS
> +static void panthor_gem_debugfs_bo_init(struct panthor_gem_object *bo)
> +{
> + INIT_LIST_HEAD(&bo->gems.node);
> + bo->gems.creator.tgid = current->group_leader->pid;
> + get_task_comm(bo->gems.creator.process_name, current->group_leader);
> +}
> +
> +static void panthor_gem_debugfs_bo_add(struct panthor_gem_object *bo)
> +{
> + struct panthor_device *ptdev = container_of(bo->base.base.dev,
> + struct panthor_device, base);
> +
> + mutex_lock(&ptdev->gems.lock);
> + list_add_tail(&bo->gems.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->gems.node))
> + return;
> +
> + mutex_lock(&ptdev->gems.lock);
> + list_del_init(&bo->gems.node);
> + mutex_unlock(&ptdev->gems.lock);
> +}
> +#else
> +static void panthor_gem_debugfs_bo_init(struct panthor_gem_object *bo) {}
> +static void panthor_gem_debugfs_bo_add(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
> @@ -206,6 +245,8 @@ 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_init(obj);
> +
> return &obj->base.base;
> }
>
> @@ -254,6 +295,8 @@ panthor_gem_create_with_handle(struct drm_file *file,
> /* drop reference from allocate - handle holds it now. */
> drm_gem_object_put(&shmem->base);
>
> + panthor_gem_debugfs_bo_add(bo);

As mentioned in the other thread, I'd be tempted to:

- merge panthor_gem_debugfs_bo_init() into panthor_gem_debugfs_bo_add()
- call panthor_gem_debugfs_bo_add() from panthor_gem_create_object()
- have a way to differentiates kernel and user BOs.

> +
> return ret;
> }
>
> @@ -285,3 +328,90 @@ panthor_gem_kernel_bo_set_label(struct panthor_kernel_bo *bo, const char *label)
>
> panthor_gem_bo_set_label(bo->obj, kstrdup_const(str, GFP_KERNEL));
> }
> +
> +#ifdef CONFIG_DEBUG_FS
> +static bool panfrost_gem_print_flag(const char *name,
> + bool is_set,
> + bool other_flags_printed,
> + struct seq_file *m)
> +{
> + if (is_set)
> + seq_printf(m, "%s%s", other_flags_printed ? "," : "", name);
> +
> + return is_set | other_flags_printed;
> +}
> +
> +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] = {};
> + bool has_flags = false;
> + size_t resident_size;
> +
> + /* 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->gems.creator.process_name, bo->gems.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));
> +
> + seq_puts(m, "(");
> + has_flags = panfrost_gem_print_flag("imported", bo->base.base.import_attach != NULL,
> + has_flags, m);
> + has_flags = panfrost_gem_print_flag("exported", bo->base.base.dma_buf != NULL,
> + has_flags, m);
> + if (bo->base.madv < 0)
> + has_flags = panfrost_gem_print_flag("purged", true, has_flags, m);
> + else if (bo->base.madv > 0)
> + has_flags = panfrost_gem_print_flag("purgeable", true, has_flags, m);
> + if (!has_flags)
> + seq_puts(m, "none");
> + seq_puts(m, ")");
> +
> + mutex_lock(&bo->label.lock);
> + seq_printf(m, "%-16s%-60s", "", bo->label.str ? : NULL);
> + mutex_unlock(&bo->label.lock);
> + 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 flags label\n");
> + seq_puts(m, "------------------------------------------------------------------------------------------------------------------------------------------------\n");
> +
> + scoped_guard(mutex, &ptdev->gems.lock) {
> + list_for_each_entry(bo, &ptdev->gems.node, gems.node)
> + 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 0582826b341a..7c896ec35801 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.h
> +++ b/drivers/gpu/drm/panthor/panthor_gem.h
> @@ -13,6 +13,26 @@
>
> struct panthor_vm;
>
> +/**
> + * 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;

Add a

bool kernel_only;

to reflect the fact the BO can't be accessed by the UMD.

> +};
> +
> /**
> * struct panthor_gem_object - Driver specific GEM object.
> */
> @@ -60,6 +80,10 @@ 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 gems;

s/gems/debugfs/

> +#endif
> };
>
> /**
> @@ -155,4 +179,9 @@ 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);
> +#endif
> +
> #endif /* __PANTHOR_GEM_H__ */

Next message: Mukesh Kumar Savaliya: "Re: [PATCH v2 2/3] i3c: master: Add Qualcomm I3C controller driver"
Previous message: Daniel Gomez: "[PATCH] kconfig: merge_config: use an empty file as initfile"
In reply to: Adrián Larumbe: "[PATCH v3 3/4] drm/panthor: show device-wide list of DRM GEM objects over DebugFS"
Next in thread: Adrián Larumbe: "[PATCH v3 2/4] drm/panthor: Add driver IOCTL for setting BO labels"
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