Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1508 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
new file mode 100644
index 0000000000..44a948b80e
--- /dev/null
+++ b/drivers/gpu/drm/drm_gem.c
@@ -0,0 +1,1508 @@
+/*
+ * Copyright © 2008 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Eric Anholt <eric@anholt.net>
+ *
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/iosys-map.h>
+#include <linux/mem_encrypt.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/module.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/shmem_fs.h>
+#include <linux/slab.h>
+#include <linux/string_helpers.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+
+#include <drm/drm.h>
+#include <drm/drm_device.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_file.h>
+#include <drm/drm_gem.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_print.h>
+#include <drm/drm_vma_manager.h>
+
+#include "drm_internal.h"
+
+/** @file drm_gem.c
+ *
+ * This file provides some of the base ioctls and library routines for
+ * the graphics memory manager implemented by each device driver.
+ *
+ * Because various devices have different requirements in terms of
+ * synchronization and migration strategies, implementing that is left up to
+ * the driver, and all that the general API provides should be generic --
+ * allocating objects, reading/writing data with the cpu, freeing objects.
+ * Even there, platform-dependent optimizations for reading/writing data with
+ * the CPU mean we'll likely hook those out to driver-specific calls.  However,
+ * the DRI2 implementation wants to have at least allocate/mmap be generic.
+ *
+ * The goal was to have swap-backed object allocation managed through
+ * struct file.  However, file descriptors as handles to a struct file have
+ * two major failings:
+ * - Process limits prevent more than 1024 or so being used at a time by
+ *   default.
+ * - Inability to allocate high fds will aggravate the X Server's select()
+ *   handling, and likely that of many GL client applications as well.
+ *
+ * This led to a plan of using our own integer IDs (called handles, following
+ * DRM terminology) to mimic fds, and implement the fd syscalls we need as
+ * ioctls.  The objects themselves will still include the struct file so
+ * that we can transition to fds if the required kernel infrastructure shows
+ * up at a later date, and as our interface with shmfs for memory allocation.
+ */
+
+static void
+drm_gem_init_release(struct drm_device *dev, void *ptr)
+{
+	drm_vma_offset_manager_destroy(dev->vma_offset_manager);
+}
+
+/**
+ * drm_gem_init - Initialize the GEM device fields
+ * @dev: drm_devic structure to initialize
+ */
+int
+drm_gem_init(struct drm_device *dev)
+{
+	struct drm_vma_offset_manager *vma_offset_manager;
+
+	mutex_init(&dev->object_name_lock);
+	idr_init_base(&dev->object_name_idr, 1);
+
+	vma_offset_manager = drmm_kzalloc(dev, sizeof(*vma_offset_manager),
+					  GFP_KERNEL);
+	if (!vma_offset_manager) {
+		DRM_ERROR("out of memory\n");
+		return -ENOMEM;
+	}
+
+	dev->vma_offset_manager = vma_offset_manager;
+	drm_vma_offset_manager_init(vma_offset_manager,
+				    DRM_FILE_PAGE_OFFSET_START,
+				    DRM_FILE_PAGE_OFFSET_SIZE);
+
+	return drmm_add_action(dev, drm_gem_init_release, NULL);
+}
+
+/**
+ * drm_gem_object_init - initialize an allocated shmem-backed GEM object
+ * @dev: drm_device the object should be initialized for
+ * @obj: drm_gem_object to initialize
+ * @size: object size
+ *
+ * Initialize an already allocated GEM object of the specified size with
+ * shmfs backing store.
+ */
+int drm_gem_object_init(struct drm_device *dev,
+			struct drm_gem_object *obj, size_t size)
+{
+	struct file *filp;
+
+	drm_gem_private_object_init(dev, obj, size);
+
+	filp = shmem_file_setup("drm mm object", size, VM_NORESERVE);
+	if (IS_ERR(filp))
+		return PTR_ERR(filp);
+
+	obj->filp = filp;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_gem_object_init);
+
+/**
+ * drm_gem_private_object_init - initialize an allocated private GEM object
+ * @dev: drm_device the object should be initialized for
+ * @obj: drm_gem_object to initialize
+ * @size: object size
+ *
+ * Initialize an already allocated GEM object of the specified size with
+ * no GEM provided backing store. Instead the caller is responsible for
+ * backing the object and handling it.
+ */
+void drm_gem_private_object_init(struct drm_device *dev,
+				 struct drm_gem_object *obj, size_t size)
+{
+	BUG_ON((size & (PAGE_SIZE - 1)) != 0);
+
+	obj->dev = dev;
+	obj->filp = NULL;
+
+	kref_init(&obj->refcount);
+	obj->handle_count = 0;
+	obj->size = size;
+	dma_resv_init(&obj->_resv);
+	if (!obj->resv)
+		obj->resv = &obj->_resv;
+
+	if (drm_core_check_feature(dev, DRIVER_GEM_GPUVA))
+		drm_gem_gpuva_init(obj);
+
+	drm_vma_node_reset(&obj->vma_node);
+	INIT_LIST_HEAD(&obj->lru_node);
+}
+EXPORT_SYMBOL(drm_gem_private_object_init);
+
+/**
+ * drm_gem_private_object_fini - Finalize a failed drm_gem_object
+ * @obj: drm_gem_object
+ *
+ * Uninitialize an already allocated GEM object when it initialized failed
+ */
+void drm_gem_private_object_fini(struct drm_gem_object *obj)
+{
+	WARN_ON(obj->dma_buf);
+
+	dma_resv_fini(&obj->_resv);
+}
+EXPORT_SYMBOL(drm_gem_private_object_fini);
+
+/**
+ * drm_gem_object_handle_free - release resources bound to userspace handles
+ * @obj: GEM object to clean up.
+ *
+ * Called after the last handle to the object has been closed
+ *
+ * Removes any name for the object. Note that this must be
+ * called before drm_gem_object_free or we'll be touching
+ * freed memory
+ */
+static void drm_gem_object_handle_free(struct drm_gem_object *obj)
+{
+	struct drm_device *dev = obj->dev;
+
+	/* Remove any name for this object */
+	if (obj->name) {
+		idr_remove(&dev->object_name_idr, obj->name);
+		obj->name = 0;
+	}
+}
+
+static void drm_gem_object_exported_dma_buf_free(struct drm_gem_object *obj)
+{
+	/* Unbreak the reference cycle if we have an exported dma_buf. */
+	if (obj->dma_buf) {
+		dma_buf_put(obj->dma_buf);
+		obj->dma_buf = NULL;
+	}
+}
+
+static void
+drm_gem_object_handle_put_unlocked(struct drm_gem_object *obj)
+{
+	struct drm_device *dev = obj->dev;
+	bool final = false;
+
+	if (WARN_ON(READ_ONCE(obj->handle_count) == 0))
+		return;
+
+	/*
+	* Must bump handle count first as this may be the last
+	* ref, in which case the object would disappear before we
+	* checked for a name
+	*/
+
+	mutex_lock(&dev->object_name_lock);
+	if (--obj->handle_count == 0) {
+		drm_gem_object_handle_free(obj);
+		drm_gem_object_exported_dma_buf_free(obj);
+		final = true;
+	}
+	mutex_unlock(&dev->object_name_lock);
+
+	if (final)
+		drm_gem_object_put(obj);
+}
+
+/*
+ * Called at device or object close to release the file's
+ * handle references on objects.
+ */
+static int
+drm_gem_object_release_handle(int id, void *ptr, void *data)
+{
+	struct drm_file *file_priv = data;
+	struct drm_gem_object *obj = ptr;
+
+	if (obj->funcs->close)
+		obj->funcs->close(obj, file_priv);
+
+	drm_prime_remove_buf_handle(&file_priv->prime, id);
+	drm_vma_node_revoke(&obj->vma_node, file_priv);
+
+	drm_gem_object_handle_put_unlocked(obj);
+
+	return 0;
+}
+
+/**
+ * drm_gem_handle_delete - deletes the given file-private handle
+ * @filp: drm file-private structure to use for the handle look up
+ * @handle: userspace handle to delete
+ *
+ * Removes the GEM handle from the @filp lookup table which has been added with
+ * drm_gem_handle_create(). If this is the last handle also cleans up linked
+ * resources like GEM names.
+ */
+int
+drm_gem_handle_delete(struct drm_file *filp, u32 handle)
+{
+	struct drm_gem_object *obj;
+
+	spin_lock(&filp->table_lock);
+
+	/* Check if we currently have a reference on the object */
+	obj = idr_replace(&filp->object_idr, NULL, handle);
+	spin_unlock(&filp->table_lock);
+	if (IS_ERR_OR_NULL(obj))
+		return -EINVAL;
+
+	/* Release driver's reference and decrement refcount. */
+	drm_gem_object_release_handle(handle, obj, filp);
+
+	/* And finally make the handle available for future allocations. */
+	spin_lock(&filp->table_lock);
+	idr_remove(&filp->object_idr, handle);
+	spin_unlock(&filp->table_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_gem_handle_delete);
+
+/**
+ * drm_gem_dumb_map_offset - return the fake mmap offset for a gem object
+ * @file: drm file-private structure containing the gem object
+ * @dev: corresponding drm_device
+ * @handle: gem object handle
+ * @offset: return location for the fake mmap offset
+ *
+ * This implements the &drm_driver.dumb_map_offset kms driver callback for
+ * drivers which use gem to manage their backing storage.
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
+			    u32 handle, u64 *offset)
+{
+	struct drm_gem_object *obj;
+	int ret;
+
+	obj = drm_gem_object_lookup(file, handle);
+	if (!obj)
+		return -ENOENT;
+
+	/* Don't allow imported objects to be mapped */
+	if (obj->import_attach) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = drm_gem_create_mmap_offset(obj);
+	if (ret)
+		goto out;
+
+	*offset = drm_vma_node_offset_addr(&obj->vma_node);
+out:
+	drm_gem_object_put(obj);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(drm_gem_dumb_map_offset);
+
+/**
+ * drm_gem_handle_create_tail - internal functions to create a handle
+ * @file_priv: drm file-private structure to register the handle for
+ * @obj: object to register
+ * @handlep: pointer to return the created handle to the caller
+ *
+ * This expects the &drm_device.object_name_lock to be held already and will
+ * drop it before returning. Used to avoid races in establishing new handles
+ * when importing an object from either an flink name or a dma-buf.
+ *
+ * Handles must be release again through drm_gem_handle_delete(). This is done
+ * when userspace closes @file_priv for all attached handles, or through the
+ * GEM_CLOSE ioctl for individual handles.
+ */
+int
+drm_gem_handle_create_tail(struct drm_file *file_priv,
+			   struct drm_gem_object *obj,
+			   u32 *handlep)
+{
+	struct drm_device *dev = obj->dev;
+	u32 handle;
+	int ret;
+
+	WARN_ON(!mutex_is_locked(&dev->object_name_lock));
+	if (obj->handle_count++ == 0)
+		drm_gem_object_get(obj);
+
+	/*
+	 * Get the user-visible handle using idr.  Preload and perform
+	 * allocation under our spinlock.
+	 */
+	idr_preload(GFP_KERNEL);
+	spin_lock(&file_priv->table_lock);
+
+	ret = idr_alloc(&file_priv->object_idr, obj, 1, 0, GFP_NOWAIT);
+
+	spin_unlock(&file_priv->table_lock);
+	idr_preload_end();
+
+	mutex_unlock(&dev->object_name_lock);
+	if (ret < 0)
+		goto err_unref;
+
+	handle = ret;
+
+	ret = drm_vma_node_allow(&obj->vma_node, file_priv);
+	if (ret)
+		goto err_remove;
+
+	if (obj->funcs->open) {
+		ret = obj->funcs->open(obj, file_priv);
+		if (ret)
+			goto err_revoke;
+	}
+
+	*handlep = handle;
+	return 0;
+
+err_revoke:
+	drm_vma_node_revoke(&obj->vma_node, file_priv);
+err_remove:
+	spin_lock(&file_priv->table_lock);
+	idr_remove(&file_priv->object_idr, handle);
+	spin_unlock(&file_priv->table_lock);
+err_unref:
+	drm_gem_object_handle_put_unlocked(obj);
+	return ret;
+}
+
+/**
+ * drm_gem_handle_create - create a gem handle for an object
+ * @file_priv: drm file-private structure to register the handle for
+ * @obj: object to register
+ * @handlep: pointer to return the created handle to the caller
+ *
+ * Create a handle for this object. This adds a handle reference to the object,
+ * which includes a regular reference count. Callers will likely want to
+ * dereference the object afterwards.
+ *
+ * Since this publishes @obj to userspace it must be fully set up by this point,
+ * drivers must call this last in their buffer object creation callbacks.
+ */
+int drm_gem_handle_create(struct drm_file *file_priv,
+			  struct drm_gem_object *obj,
+			  u32 *handlep)
+{
+	mutex_lock(&obj->dev->object_name_lock);
+
+	return drm_gem_handle_create_tail(file_priv, obj, handlep);
+}
+EXPORT_SYMBOL(drm_gem_handle_create);
+
+
+/**
+ * drm_gem_free_mmap_offset - release a fake mmap offset for an object
+ * @obj: obj in question
+ *
+ * This routine frees fake offsets allocated by drm_gem_create_mmap_offset().
+ *
+ * Note that drm_gem_object_release() already calls this function, so drivers
+ * don't have to take care of releasing the mmap offset themselves when freeing
+ * the GEM object.
+ */
+void
+drm_gem_free_mmap_offset(struct drm_gem_object *obj)
+{
+	struct drm_device *dev = obj->dev;
+
+	drm_vma_offset_remove(dev->vma_offset_manager, &obj->vma_node);
+}
+EXPORT_SYMBOL(drm_gem_free_mmap_offset);
+
+/**
+ * drm_gem_create_mmap_offset_size - create a fake mmap offset for an object
+ * @obj: obj in question
+ * @size: the virtual size
+ *
+ * GEM memory mapping works by handing back to userspace a fake mmap offset
+ * it can use in a subsequent mmap(2) call.  The DRM core code then looks
+ * up the object based on the offset and sets up the various memory mapping
+ * structures.
+ *
+ * This routine allocates and attaches a fake offset for @obj, in cases where
+ * the virtual size differs from the physical size (ie. &drm_gem_object.size).
+ * Otherwise just use drm_gem_create_mmap_offset().
+ *
+ * This function is idempotent and handles an already allocated mmap offset
+ * transparently. Drivers do not need to check for this case.
+ */
+int
+drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size)
+{
+	struct drm_device *dev = obj->dev;
+
+	return drm_vma_offset_add(dev->vma_offset_manager, &obj->vma_node,
+				  size / PAGE_SIZE);
+}
+EXPORT_SYMBOL(drm_gem_create_mmap_offset_size);
+
+/**
+ * drm_gem_create_mmap_offset - create a fake mmap offset for an object
+ * @obj: obj in question
+ *
+ * GEM memory mapping works by handing back to userspace a fake mmap offset
+ * it can use in a subsequent mmap(2) call.  The DRM core code then looks
+ * up the object based on the offset and sets up the various memory mapping
+ * structures.
+ *
+ * This routine allocates and attaches a fake offset for @obj.
+ *
+ * Drivers can call drm_gem_free_mmap_offset() before freeing @obj to release
+ * the fake offset again.
+ */
+int drm_gem_create_mmap_offset(struct drm_gem_object *obj)
+{
+	return drm_gem_create_mmap_offset_size(obj, obj->size);
+}
+EXPORT_SYMBOL(drm_gem_create_mmap_offset);
+
+/*
+ * Move folios to appropriate lru and release the folios, decrementing the
+ * ref count of those folios.
+ */
+static void drm_gem_check_release_batch(struct folio_batch *fbatch)
+{
+	check_move_unevictable_folios(fbatch);
+	__folio_batch_release(fbatch);
+	cond_resched();
+}
+
+/**
+ * drm_gem_get_pages - helper to allocate backing pages for a GEM object
+ * from shmem
+ * @obj: obj in question
+ *
+ * This reads the page-array of the shmem-backing storage of the given gem
+ * object. An array of pages is returned. If a page is not allocated or
+ * swapped-out, this will allocate/swap-in the required pages. Note that the
+ * whole object is covered by the page-array and pinned in memory.
+ *
+ * Use drm_gem_put_pages() to release the array and unpin all pages.
+ *
+ * This uses the GFP-mask set on the shmem-mapping (see mapping_set_gfp_mask()).
+ * If you require other GFP-masks, you have to do those allocations yourself.
+ *
+ * Note that you are not allowed to change gfp-zones during runtime. That is,
+ * shmem_read_mapping_page_gfp() must be called with the same gfp_zone(gfp) as
+ * set during initialization. If you have special zone constraints, set them
+ * after drm_gem_object_init() via mapping_set_gfp_mask(). shmem-core takes care
+ * to keep pages in the required zone during swap-in.
+ *
+ * This function is only valid on objects initialized with
+ * drm_gem_object_init(), but not for those initialized with
+ * drm_gem_private_object_init() only.
+ */
+struct page **drm_gem_get_pages(struct drm_gem_object *obj)
+{
+	struct address_space *mapping;
+	struct page **pages;
+	struct folio *folio;
+	struct folio_batch fbatch;
+	long i, j, npages;
+
+	if (WARN_ON(!obj->filp))
+		return ERR_PTR(-EINVAL);
+
+	/* This is the shared memory object that backs the GEM resource */
+	mapping = obj->filp->f_mapping;
+
+	/* We already BUG_ON() for non-page-aligned sizes in
+	 * drm_gem_object_init(), so we should never hit this unless
+	 * driver author is doing something really wrong:
+	 */
+	WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);
+
+	npages = obj->size >> PAGE_SHIFT;
+
+	pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
+	if (pages == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	mapping_set_unevictable(mapping);
+
+	i = 0;
+	while (i < npages) {
+		long nr;
+		folio = shmem_read_folio_gfp(mapping, i,
+				mapping_gfp_mask(mapping));
+		if (IS_ERR(folio))
+			goto fail;
+		nr = min(npages - i, folio_nr_pages(folio));
+		for (j = 0; j < nr; j++, i++)
+			pages[i] = folio_file_page(folio, i);
+
+		/* Make sure shmem keeps __GFP_DMA32 allocated pages in the
+		 * correct region during swapin. Note that this requires
+		 * __GFP_DMA32 to be set in mapping_gfp_mask(inode->i_mapping)
+		 * so shmem can relocate pages during swapin if required.
+		 */
+		BUG_ON(mapping_gfp_constraint(mapping, __GFP_DMA32) &&
+				(folio_pfn(folio) >= 0x00100000UL));
+	}
+
+	return pages;
+
+fail:
+	mapping_clear_unevictable(mapping);
+	folio_batch_init(&fbatch);
+	j = 0;
+	while (j < i) {
+		struct folio *f = page_folio(pages[j]);
+		if (!folio_batch_add(&fbatch, f))
+			drm_gem_check_release_batch(&fbatch);
+		j += folio_nr_pages(f);
+	}
+	if (fbatch.nr)
+		drm_gem_check_release_batch(&fbatch);
+
+	kvfree(pages);
+	return ERR_CAST(folio);
+}
+EXPORT_SYMBOL(drm_gem_get_pages);
+
+/**
+ * drm_gem_put_pages - helper to free backing pages for a GEM object
+ * @obj: obj in question
+ * @pages: pages to free
+ * @dirty: if true, pages will be marked as dirty
+ * @accessed: if true, the pages will be marked as accessed
+ */
+void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
+		bool dirty, bool accessed)
+{
+	int i, npages;
+	struct address_space *mapping;
+	struct folio_batch fbatch;
+
+	mapping = file_inode(obj->filp)->i_mapping;
+	mapping_clear_unevictable(mapping);
+
+	/* We already BUG_ON() for non-page-aligned sizes in
+	 * drm_gem_object_init(), so we should never hit this unless
+	 * driver author is doing something really wrong:
+	 */
+	WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);
+
+	npages = obj->size >> PAGE_SHIFT;
+
+	folio_batch_init(&fbatch);
+	for (i = 0; i < npages; i++) {
+		struct folio *folio;
+
+		if (!pages[i])
+			continue;
+		folio = page_folio(pages[i]);
+
+		if (dirty)
+			folio_mark_dirty(folio);
+
+		if (accessed)
+			folio_mark_accessed(folio);
+
+		/* Undo the reference we took when populating the table */
+		if (!folio_batch_add(&fbatch, folio))
+			drm_gem_check_release_batch(&fbatch);
+		i += folio_nr_pages(folio) - 1;
+	}
+	if (folio_batch_count(&fbatch))
+		drm_gem_check_release_batch(&fbatch);
+
+	kvfree(pages);
+}
+EXPORT_SYMBOL(drm_gem_put_pages);
+
+static int objects_lookup(struct drm_file *filp, u32 *handle, int count,
+			  struct drm_gem_object **objs)
+{
+	int i, ret = 0;
+	struct drm_gem_object *obj;
+
+	spin_lock(&filp->table_lock);
+
+	for (i = 0; i < count; i++) {
+		/* Check if we currently have a reference on the object */
+		obj = idr_find(&filp->object_idr, handle[i]);
+		if (!obj) {
+			ret = -ENOENT;
+			break;
+		}
+		drm_gem_object_get(obj);
+		objs[i] = obj;
+	}
+	spin_unlock(&filp->table_lock);
+
+	return ret;
+}
+
+/**
+ * drm_gem_objects_lookup - look up GEM objects from an array of handles
+ * @filp: DRM file private date
+ * @bo_handles: user pointer to array of userspace handle
+ * @count: size of handle array
+ * @objs_out: returned pointer to array of drm_gem_object pointers
+ *
+ * Takes an array of userspace handles and returns a newly allocated array of
+ * GEM objects.
+ *
+ * For a single handle lookup, use drm_gem_object_lookup().
+ *
+ * Returns:
+ *
+ * @objs filled in with GEM object pointers. Returned GEM objects need to be
+ * released with drm_gem_object_put(). -ENOENT is returned on a lookup
+ * failure. 0 is returned on success.
+ *
+ */
+int drm_gem_objects_lookup(struct drm_file *filp, void __user *bo_handles,
+			   int count, struct drm_gem_object ***objs_out)
+{
+	int ret;
+	u32 *handles;
+	struct drm_gem_object **objs;
+
+	if (!count)
+		return 0;
+
+	objs = kvmalloc_array(count, sizeof(struct drm_gem_object *),
+			     GFP_KERNEL | __GFP_ZERO);
+	if (!objs)
+		return -ENOMEM;
+
+	*objs_out = objs;
+
+	handles = kvmalloc_array(count, sizeof(u32), GFP_KERNEL);
+	if (!handles) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	if (copy_from_user(handles, bo_handles, count * sizeof(u32))) {
+		ret = -EFAULT;
+		DRM_DEBUG("Failed to copy in GEM handles\n");
+		goto out;
+	}
+
+	ret = objects_lookup(filp, handles, count, objs);
+out:
+	kvfree(handles);
+	return ret;
+
+}
+EXPORT_SYMBOL(drm_gem_objects_lookup);
+
+/**
+ * drm_gem_object_lookup - look up a GEM object from its handle
+ * @filp: DRM file private date
+ * @handle: userspace handle
+ *
+ * Returns:
+ *
+ * A reference to the object named by the handle if such exists on @filp, NULL
+ * otherwise.
+ *
+ * If looking up an array of handles, use drm_gem_objects_lookup().
+ */
+struct drm_gem_object *
+drm_gem_object_lookup(struct drm_file *filp, u32 handle)
+{
+	struct drm_gem_object *obj = NULL;
+
+	objects_lookup(filp, &handle, 1, &obj);
+	return obj;
+}
+EXPORT_SYMBOL(drm_gem_object_lookup);
+
+/**
+ * drm_gem_dma_resv_wait - Wait on GEM object's reservation's objects
+ * shared and/or exclusive fences.
+ * @filep: DRM file private date
+ * @handle: userspace handle
+ * @wait_all: if true, wait on all fences, else wait on just exclusive fence
+ * @timeout: timeout value in jiffies or zero to return immediately
+ *
+ * Returns:
+ *
+ * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
+ * greater than 0 on success.
+ */
+long drm_gem_dma_resv_wait(struct drm_file *filep, u32 handle,
+				    bool wait_all, unsigned long timeout)
+{
+	long ret;
+	struct drm_gem_object *obj;
+
+	obj = drm_gem_object_lookup(filep, handle);
+	if (!obj) {
+		DRM_DEBUG("Failed to look up GEM BO %d\n", handle);
+		return -EINVAL;
+	}
+
+	ret = dma_resv_wait_timeout(obj->resv, dma_resv_usage_rw(wait_all),
+				    true, timeout);
+	if (ret == 0)
+		ret = -ETIME;
+	else if (ret > 0)
+		ret = 0;
+
+	drm_gem_object_put(obj);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_dma_resv_wait);
+
+/**
+ * drm_gem_close_ioctl - implementation of the GEM_CLOSE ioctl
+ * @dev: drm_device
+ * @data: ioctl data
+ * @file_priv: drm file-private structure
+ *
+ * Releases the handle to an mm object.
+ */
+int
+drm_gem_close_ioctl(struct drm_device *dev, void *data,
+		    struct drm_file *file_priv)
+{
+	struct drm_gem_close *args = data;
+	int ret;
+
+	if (!drm_core_check_feature(dev, DRIVER_GEM))
+		return -EOPNOTSUPP;
+
+	ret = drm_gem_handle_delete(file_priv, args->handle);
+
+	return ret;
+}
+
+/**
+ * drm_gem_flink_ioctl - implementation of the GEM_FLINK ioctl
+ * @dev: drm_device
+ * @data: ioctl data
+ * @file_priv: drm file-private structure
+ *
+ * Create a global name for an object, returning the name.
+ *
+ * Note that the name does not hold a reference; when the object
+ * is freed, the name goes away.
+ */
+int
+drm_gem_flink_ioctl(struct drm_device *dev, void *data,
+		    struct drm_file *file_priv)
+{
+	struct drm_gem_flink *args = data;
+	struct drm_gem_object *obj;
+	int ret;
+
+	if (!drm_core_check_feature(dev, DRIVER_GEM))
+		return -EOPNOTSUPP;
+
+	obj = drm_gem_object_lookup(file_priv, args->handle);
+	if (obj == NULL)
+		return -ENOENT;
+
+	mutex_lock(&dev->object_name_lock);
+	/* prevent races with concurrent gem_close. */
+	if (obj->handle_count == 0) {
+		ret = -ENOENT;
+		goto err;
+	}
+
+	if (!obj->name) {
+		ret = idr_alloc(&dev->object_name_idr, obj, 1, 0, GFP_KERNEL);
+		if (ret < 0)
+			goto err;
+
+		obj->name = ret;
+	}
+
+	args->name = (uint64_t) obj->name;
+	ret = 0;
+
+err:
+	mutex_unlock(&dev->object_name_lock);
+	drm_gem_object_put(obj);
+	return ret;
+}
+
+/**
+ * drm_gem_open_ioctl - implementation of the GEM_OPEN ioctl
+ * @dev: drm_device
+ * @data: ioctl data
+ * @file_priv: drm file-private structure
+ *
+ * Open an object using the global name, returning a handle and the size.
+ *
+ * This handle (of course) holds a reference to the object, so the object
+ * will not go away until the handle is deleted.
+ */
+int
+drm_gem_open_ioctl(struct drm_device *dev, void *data,
+		   struct drm_file *file_priv)
+{
+	struct drm_gem_open *args = data;
+	struct drm_gem_object *obj;
+	int ret;
+	u32 handle;
+
+	if (!drm_core_check_feature(dev, DRIVER_GEM))
+		return -EOPNOTSUPP;
+
+	mutex_lock(&dev->object_name_lock);
+	obj = idr_find(&dev->object_name_idr, (int) args->name);
+	if (obj) {
+		drm_gem_object_get(obj);
+	} else {
+		mutex_unlock(&dev->object_name_lock);
+		return -ENOENT;
+	}
+
+	/* drm_gem_handle_create_tail unlocks dev->object_name_lock. */
+	ret = drm_gem_handle_create_tail(file_priv, obj, &handle);
+	if (ret)
+		goto err;
+
+	args->handle = handle;
+	args->size = obj->size;
+
+err:
+	drm_gem_object_put(obj);
+	return ret;
+}
+
+/**
+ * drm_gem_open - initializes GEM file-private structures at devnode open time
+ * @dev: drm_device which is being opened by userspace
+ * @file_private: drm file-private structure to set up
+ *
+ * Called at device open time, sets up the structure for handling refcounting
+ * of mm objects.
+ */
+void
+drm_gem_open(struct drm_device *dev, struct drm_file *file_private)
+{
+	idr_init_base(&file_private->object_idr, 1);
+	spin_lock_init(&file_private->table_lock);
+}
+
+/**
+ * drm_gem_release - release file-private GEM resources
+ * @dev: drm_device which is being closed by userspace
+ * @file_private: drm file-private structure to clean up
+ *
+ * Called at close time when the filp is going away.
+ *
+ * Releases any remaining references on objects by this filp.
+ */
+void
+drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
+{
+	idr_for_each(&file_private->object_idr,
+		     &drm_gem_object_release_handle, file_private);
+	idr_destroy(&file_private->object_idr);
+}
+
+/**
+ * drm_gem_object_release - release GEM buffer object resources
+ * @obj: GEM buffer object
+ *
+ * This releases any structures and resources used by @obj and is the inverse of
+ * drm_gem_object_init().
+ */
+void
+drm_gem_object_release(struct drm_gem_object *obj)
+{
+	if (obj->filp)
+		fput(obj->filp);
+
+	drm_gem_private_object_fini(obj);
+
+	drm_gem_free_mmap_offset(obj);
+	drm_gem_lru_remove(obj);
+}
+EXPORT_SYMBOL(drm_gem_object_release);
+
+/**
+ * drm_gem_object_free - free a GEM object
+ * @kref: kref of the object to free
+ *
+ * Called after the last reference to the object has been lost.
+ *
+ * Frees the object
+ */
+void
+drm_gem_object_free(struct kref *kref)
+{
+	struct drm_gem_object *obj =
+		container_of(kref, struct drm_gem_object, refcount);
+
+	if (WARN_ON(!obj->funcs->free))
+		return;
+
+	obj->funcs->free(obj);
+}
+EXPORT_SYMBOL(drm_gem_object_free);
+
+/**
+ * drm_gem_vm_open - vma->ops->open implementation for GEM
+ * @vma: VM area structure
+ *
+ * This function implements the #vm_operations_struct open() callback for GEM
+ * drivers. This must be used together with drm_gem_vm_close().
+ */
+void drm_gem_vm_open(struct vm_area_struct *vma)
+{
+	struct drm_gem_object *obj = vma->vm_private_data;
+
+	drm_gem_object_get(obj);
+}
+EXPORT_SYMBOL(drm_gem_vm_open);
+
+/**
+ * drm_gem_vm_close - vma->ops->close implementation for GEM
+ * @vma: VM area structure
+ *
+ * This function implements the #vm_operations_struct close() callback for GEM
+ * drivers. This must be used together with drm_gem_vm_open().
+ */
+void drm_gem_vm_close(struct vm_area_struct *vma)
+{
+	struct drm_gem_object *obj = vma->vm_private_data;
+
+	drm_gem_object_put(obj);
+}
+EXPORT_SYMBOL(drm_gem_vm_close);
+
+/**
+ * drm_gem_mmap_obj - memory map a GEM object
+ * @obj: the GEM object to map
+ * @obj_size: the object size to be mapped, in bytes
+ * @vma: VMA for the area to be mapped
+ *
+ * Set up the VMA to prepare mapping of the GEM object using the GEM object's
+ * vm_ops. Depending on their requirements, GEM objects can either
+ * provide a fault handler in their vm_ops (in which case any accesses to
+ * the object will be trapped, to perform migration, GTT binding, surface
+ * register allocation, or performance monitoring), or mmap the buffer memory
+ * synchronously after calling drm_gem_mmap_obj.
+ *
+ * This function is mainly intended to implement the DMABUF mmap operation, when
+ * the GEM object is not looked up based on its fake offset. To implement the
+ * DRM mmap operation, drivers should use the drm_gem_mmap() function.
+ *
+ * drm_gem_mmap_obj() assumes the user is granted access to the buffer while
+ * drm_gem_mmap() prevents unprivileged users from mapping random objects. So
+ * callers must verify access restrictions before calling this helper.
+ *
+ * Return 0 or success or -EINVAL if the object size is smaller than the VMA
+ * size, or if no vm_ops are provided.
+ */
+int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
+		     struct vm_area_struct *vma)
+{
+	int ret;
+
+	/* Check for valid size. */
+	if (obj_size < vma->vm_end - vma->vm_start)
+		return -EINVAL;
+
+	/* Take a ref for this mapping of the object, so that the fault
+	 * handler can dereference the mmap offset's pointer to the object.
+	 * This reference is cleaned up by the corresponding vm_close
+	 * (which should happen whether the vma was created by this call, or
+	 * by a vm_open due to mremap or partial unmap or whatever).
+	 */
+	drm_gem_object_get(obj);
+
+	vma->vm_private_data = obj;
+	vma->vm_ops = obj->funcs->vm_ops;
+
+	if (obj->funcs->mmap) {
+		ret = obj->funcs->mmap(obj, vma);
+		if (ret)
+			goto err_drm_gem_object_put;
+		WARN_ON(!(vma->vm_flags & VM_DONTEXPAND));
+	} else {
+		if (!vma->vm_ops) {
+			ret = -EINVAL;
+			goto err_drm_gem_object_put;
+		}
+
+		vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
+		vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
+		vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
+	}
+
+	return 0;
+
+err_drm_gem_object_put:
+	drm_gem_object_put(obj);
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_mmap_obj);
+
+/**
+ * drm_gem_mmap - memory map routine for GEM objects
+ * @filp: DRM file pointer
+ * @vma: VMA for the area to be mapped
+ *
+ * If a driver supports GEM object mapping, mmap calls on the DRM file
+ * descriptor will end up here.
+ *
+ * Look up the GEM object based on the offset passed in (vma->vm_pgoff will
+ * contain the fake offset we created when the GTT map ioctl was called on
+ * the object) and map it with a call to drm_gem_mmap_obj().
+ *
+ * If the caller is not granted access to the buffer object, the mmap will fail
+ * with EACCES. Please see the vma manager for more information.
+ */
+int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct drm_file *priv = filp->private_data;
+	struct drm_device *dev = priv->minor->dev;
+	struct drm_gem_object *obj = NULL;
+	struct drm_vma_offset_node *node;
+	int ret;
+
+	if (drm_dev_is_unplugged(dev))
+		return -ENODEV;
+
+	drm_vma_offset_lock_lookup(dev->vma_offset_manager);
+	node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
+						  vma->vm_pgoff,
+						  vma_pages(vma));
+	if (likely(node)) {
+		obj = container_of(node, struct drm_gem_object, vma_node);
+		/*
+		 * When the object is being freed, after it hits 0-refcnt it
+		 * proceeds to tear down the object. In the process it will
+		 * attempt to remove the VMA offset and so acquire this
+		 * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
+		 * that matches our range, we know it is in the process of being
+		 * destroyed and will be freed as soon as we release the lock -
+		 * so we have to check for the 0-refcnted object and treat it as
+		 * invalid.
+		 */
+		if (!kref_get_unless_zero(&obj->refcount))
+			obj = NULL;
+	}
+	drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
+
+	if (!obj)
+		return -EINVAL;
+
+	if (!drm_vma_node_is_allowed(node, priv)) {
+		drm_gem_object_put(obj);
+		return -EACCES;
+	}
+
+	ret = drm_gem_mmap_obj(obj, drm_vma_node_size(node) << PAGE_SHIFT,
+			       vma);
+
+	drm_gem_object_put(obj);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_mmap);
+
+void drm_gem_print_info(struct drm_printer *p, unsigned int indent,
+			const struct drm_gem_object *obj)
+{
+	drm_printf_indent(p, indent, "name=%d\n", obj->name);
+	drm_printf_indent(p, indent, "refcount=%u\n",
+			  kref_read(&obj->refcount));
+	drm_printf_indent(p, indent, "start=%08lx\n",
+			  drm_vma_node_start(&obj->vma_node));
+	drm_printf_indent(p, indent, "size=%zu\n", obj->size);
+	drm_printf_indent(p, indent, "imported=%s\n",
+			  str_yes_no(obj->import_attach));
+
+	if (obj->funcs->print_info)
+		obj->funcs->print_info(p, indent, obj);
+}
+
+int drm_gem_pin(struct drm_gem_object *obj)
+{
+	if (obj->funcs->pin)
+		return obj->funcs->pin(obj);
+
+	return 0;
+}
+
+void drm_gem_unpin(struct drm_gem_object *obj)
+{
+	if (obj->funcs->unpin)
+		obj->funcs->unpin(obj);
+}
+
+int drm_gem_vmap(struct drm_gem_object *obj, struct iosys_map *map)
+{
+	int ret;
+
+	dma_resv_assert_held(obj->resv);
+
+	if (!obj->funcs->vmap)
+		return -EOPNOTSUPP;
+
+	ret = obj->funcs->vmap(obj, map);
+	if (ret)
+		return ret;
+	else if (iosys_map_is_null(map))
+		return -ENOMEM;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_gem_vmap);
+
+void drm_gem_vunmap(struct drm_gem_object *obj, struct iosys_map *map)
+{
+	dma_resv_assert_held(obj->resv);
+
+	if (iosys_map_is_null(map))
+		return;
+
+	if (obj->funcs->vunmap)
+		obj->funcs->vunmap(obj, map);
+
+	/* Always set the mapping to NULL. Callers may rely on this. */
+	iosys_map_clear(map);
+}
+EXPORT_SYMBOL(drm_gem_vunmap);
+
+int drm_gem_vmap_unlocked(struct drm_gem_object *obj, struct iosys_map *map)
+{
+	int ret;
+
+	dma_resv_lock(obj->resv, NULL);
+	ret = drm_gem_vmap(obj, map);
+	dma_resv_unlock(obj->resv);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_vmap_unlocked);
+
+void drm_gem_vunmap_unlocked(struct drm_gem_object *obj, struct iosys_map *map)
+{
+	dma_resv_lock(obj->resv, NULL);
+	drm_gem_vunmap(obj, map);
+	dma_resv_unlock(obj->resv);
+}
+EXPORT_SYMBOL(drm_gem_vunmap_unlocked);
+
+/**
+ * drm_gem_lock_reservations - Sets up the ww context and acquires
+ * the lock on an array of GEM objects.
+ *
+ * Once you've locked your reservations, you'll want to set up space
+ * for your shared fences (if applicable), submit your job, then
+ * drm_gem_unlock_reservations().
+ *
+ * @objs: drm_gem_objects to lock
+ * @count: Number of objects in @objs
+ * @acquire_ctx: struct ww_acquire_ctx that will be initialized as
+ * part of tracking this set of locked reservations.
+ */
+int
+drm_gem_lock_reservations(struct drm_gem_object **objs, int count,
+			  struct ww_acquire_ctx *acquire_ctx)
+{
+	int contended = -1;
+	int i, ret;
+
+	ww_acquire_init(acquire_ctx, &reservation_ww_class);
+
+retry:
+	if (contended != -1) {
+		struct drm_gem_object *obj = objs[contended];
+
+		ret = dma_resv_lock_slow_interruptible(obj->resv,
+								 acquire_ctx);
+		if (ret) {
+			ww_acquire_fini(acquire_ctx);
+			return ret;
+		}
+	}
+
+	for (i = 0; i < count; i++) {
+		if (i == contended)
+			continue;
+
+		ret = dma_resv_lock_interruptible(objs[i]->resv,
+							    acquire_ctx);
+		if (ret) {
+			int j;
+
+			for (j = 0; j < i; j++)
+				dma_resv_unlock(objs[j]->resv);
+
+			if (contended != -1 && contended >= i)
+				dma_resv_unlock(objs[contended]->resv);
+
+			if (ret == -EDEADLK) {
+				contended = i;
+				goto retry;
+			}
+
+			ww_acquire_fini(acquire_ctx);
+			return ret;
+		}
+	}
+
+	ww_acquire_done(acquire_ctx);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_gem_lock_reservations);
+
+void
+drm_gem_unlock_reservations(struct drm_gem_object **objs, int count,
+			    struct ww_acquire_ctx *acquire_ctx)
+{
+	int i;
+
+	for (i = 0; i < count; i++)
+		dma_resv_unlock(objs[i]->resv);
+
+	ww_acquire_fini(acquire_ctx);
+}
+EXPORT_SYMBOL(drm_gem_unlock_reservations);
+
+/**
+ * drm_gem_lru_init - initialize a LRU
+ *
+ * @lru: The LRU to initialize
+ * @lock: The lock protecting the LRU
+ */
+void
+drm_gem_lru_init(struct drm_gem_lru *lru, struct mutex *lock)
+{
+	lru->lock = lock;
+	lru->count = 0;
+	INIT_LIST_HEAD(&lru->list);
+}
+EXPORT_SYMBOL(drm_gem_lru_init);
+
+static void
+drm_gem_lru_remove_locked(struct drm_gem_object *obj)
+{
+	obj->lru->count -= obj->size >> PAGE_SHIFT;
+	WARN_ON(obj->lru->count < 0);
+	list_del(&obj->lru_node);
+	obj->lru = NULL;
+}
+
+/**
+ * drm_gem_lru_remove - remove object from whatever LRU it is in
+ *
+ * If the object is currently in any LRU, remove it.
+ *
+ * @obj: The GEM object to remove from current LRU
+ */
+void
+drm_gem_lru_remove(struct drm_gem_object *obj)
+{
+	struct drm_gem_lru *lru = obj->lru;
+
+	if (!lru)
+		return;
+
+	mutex_lock(lru->lock);
+	drm_gem_lru_remove_locked(obj);
+	mutex_unlock(lru->lock);
+}
+EXPORT_SYMBOL(drm_gem_lru_remove);
+
+/**
+ * drm_gem_lru_move_tail_locked - move the object to the tail of the LRU
+ *
+ * Like &drm_gem_lru_move_tail but lru lock must be held
+ *
+ * @lru: The LRU to move the object into.
+ * @obj: The GEM object to move into this LRU
+ */
+void
+drm_gem_lru_move_tail_locked(struct drm_gem_lru *lru, struct drm_gem_object *obj)
+{
+	lockdep_assert_held_once(lru->lock);
+
+	if (obj->lru)
+		drm_gem_lru_remove_locked(obj);
+
+	lru->count += obj->size >> PAGE_SHIFT;
+	list_add_tail(&obj->lru_node, &lru->list);
+	obj->lru = lru;
+}
+EXPORT_SYMBOL(drm_gem_lru_move_tail_locked);
+
+/**
+ * drm_gem_lru_move_tail - move the object to the tail of the LRU
+ *
+ * If the object is already in this LRU it will be moved to the
+ * tail.  Otherwise it will be removed from whichever other LRU
+ * it is in (if any) and moved into this LRU.
+ *
+ * @lru: The LRU to move the object into.
+ * @obj: The GEM object to move into this LRU
+ */
+void
+drm_gem_lru_move_tail(struct drm_gem_lru *lru, struct drm_gem_object *obj)
+{
+	mutex_lock(lru->lock);
+	drm_gem_lru_move_tail_locked(lru, obj);
+	mutex_unlock(lru->lock);
+}
+EXPORT_SYMBOL(drm_gem_lru_move_tail);
+
+/**
+ * drm_gem_lru_scan - helper to implement shrinker.scan_objects
+ *
+ * If the shrink callback succeeds, it is expected that the driver
+ * move the object out of this LRU.
+ *
+ * If the LRU possibly contain active buffers, it is the responsibility
+ * of the shrink callback to check for this (ie. dma_resv_test_signaled())
+ * or if necessary block until the buffer becomes idle.
+ *
+ * @lru: The LRU to scan
+ * @nr_to_scan: The number of pages to try to reclaim
+ * @remaining: The number of pages left to reclaim, should be initialized by caller
+ * @shrink: Callback to try to shrink/reclaim the object.
+ */
+unsigned long
+drm_gem_lru_scan(struct drm_gem_lru *lru,
+		 unsigned int nr_to_scan,
+		 unsigned long *remaining,
+		 bool (*shrink)(struct drm_gem_object *obj))
+{
+	struct drm_gem_lru still_in_lru;
+	struct drm_gem_object *obj;
+	unsigned freed = 0;
+
+	drm_gem_lru_init(&still_in_lru, lru->lock);
+
+	mutex_lock(lru->lock);
+
+	while (freed < nr_to_scan) {
+		obj = list_first_entry_or_null(&lru->list, typeof(*obj), lru_node);
+
+		if (!obj)
+			break;
+
+		drm_gem_lru_move_tail_locked(&still_in_lru, obj);
+
+		/*
+		 * If it's in the process of being freed, gem_object->free()
+		 * may be blocked on lock waiting to remove it.  So just
+		 * skip it.
+		 */
+		if (!kref_get_unless_zero(&obj->refcount))
+			continue;
+
+		/*
+		 * Now that we own a reference, we can drop the lock for the
+		 * rest of the loop body, to reduce contention with other
+		 * code paths that need the LRU lock
+		 */
+		mutex_unlock(lru->lock);
+
+		/*
+		 * Note that this still needs to be trylock, since we can
+		 * hit shrinker in response to trying to get backing pages
+		 * for this obj (ie. while it's lock is already held)
+		 */
+		if (!dma_resv_trylock(obj->resv)) {
+			*remaining += obj->size >> PAGE_SHIFT;
+			goto tail;
+		}
+
+		if (shrink(obj)) {
+			freed += obj->size >> PAGE_SHIFT;
+
+			/*
+			 * If we succeeded in releasing the object's backing
+			 * pages, we expect the driver to have moved the object
+			 * out of this LRU
+			 */
+			WARN_ON(obj->lru == &still_in_lru);
+			WARN_ON(obj->lru == lru);
+		}
+
+		dma_resv_unlock(obj->resv);
+
+tail:
+		drm_gem_object_put(obj);
+		mutex_lock(lru->lock);
+	}
+
+	/*
+	 * Move objects we've skipped over out of the temporary still_in_lru
+	 * back into this LRU
+	 */
+	list_for_each_entry (obj, &still_in_lru.list, lru_node)
+		obj->lru = lru;
+	list_splice_tail(&still_in_lru.list, &lru->list);
+	lru->count += still_in_lru.count;
+
+	mutex_unlock(lru->lock);
+
+	return freed;
+}
+EXPORT_SYMBOL(drm_gem_lru_scan);
+
+/**
+ * drm_gem_evict - helper to evict backing pages for a GEM object
+ * @obj: obj in question
+ */
+int drm_gem_evict(struct drm_gem_object *obj)
+{
+	dma_resv_assert_held(obj->resv);
+
+	if (!dma_resv_test_signaled(obj->resv, DMA_RESV_USAGE_READ))
+		return -EBUSY;
+
+	if (obj->funcs->evict)
+		return obj->funcs->evict(obj);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_gem_evict);