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Message-ID: <6axzrtsyny3ruedslzq3f3m5dg3gh67utjz7cnccytprktymbc@7iawu52m23su>
Date: Wed, 2 Apr 2025 13:09:13 +0100
From: Adrián Larumbe <adrian.larumbe@...labora.com>
To: Boris Brezillon <boris.brezillon@...labora.com>
Cc: Steven Price <steven.price@....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 v3 3/4] drm/panthor: show device-wide list of DRM GEM
objects over DebugFS
Hi Boris,
On 28.03.2025 15:30, Boris Brezillon wrote:
> On Thu, 27 Mar 2025 14:08:36 +0000
> Adrián Larumbe <adrian.larumbe@...labora.com> 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@...labora.com>
> > ---
> > 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@...nel.org> */
> > /* 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()
I did this at first, but then realised it would make it harder to pass a
bo_type mask to the add function to be able to tell kernel or FW-bound
BO's apart from UM or GPU ones, because this would be decided by the
code path in which they're created.
> - 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__ */
Adrian Larumbe
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