path: root/drivers/gpu/drm/drm_buddy.c

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2021 Intel Corporation
 */

#include <linux/kmemleak.h>
#include <linux/module.h>
#include <linux/sizes.h>

#include <drm/drm_buddy.h>

static struct kmem_cache *slab_blocks;

static struct drm_buddy_block *drm_block_alloc(struct drm_buddy *mm,
					       struct drm_buddy_block *parent,
					       unsigned int order,
					       u64 offset)
{
	struct drm_buddy_block *block;

	BUG_ON(order > DRM_BUDDY_MAX_ORDER);

	block = kmem_cache_zalloc(slab_blocks, GFP_KERNEL);
	if (!block)
		return NULL;

	block->header = offset;
	block->header |= order;
	block->parent = parent;

	BUG_ON(block->header & DRM_BUDDY_HEADER_UNUSED);
	return block;
}

static void drm_block_free(struct drm_buddy *mm,
			   struct drm_buddy_block *block)
{
	kmem_cache_free(slab_blocks, block);
}

static void list_insert_sorted(struct drm_buddy *mm,
			       struct drm_buddy_block *block)
{
	struct drm_buddy_block *node;
	struct list_head *head;

	head = &mm->free_list[drm_buddy_block_order(block)];
	if (list_empty(head)) {
		list_add(&block->link, head);
		return;
	}

	list_for_each_entry(node, head, link)
		if (drm_buddy_block_offset(block) < drm_buddy_block_offset(node))
			break;

	__list_add(&block->link, node->link.prev, &node->link);
}

static void mark_allocated(struct drm_buddy_block *block)
{
	block->header &= ~DRM_BUDDY_HEADER_STATE;
	block->header |= DRM_BUDDY_ALLOCATED;

	list_del(&block->link);
}

static void mark_free(struct drm_buddy *mm,
		      struct drm_buddy_block *block)
{
	block->header &= ~DRM_BUDDY_HEADER_STATE;
	block->header |= DRM_BUDDY_FREE;

	list_insert_sorted(mm, block);
}

static void mark_split(struct drm_buddy_block *block)
{
	block->header &= ~DRM_BUDDY_HEADER_STATE;
	block->header |= DRM_BUDDY_SPLIT;

	list_del(&block->link);
}

/**
 * drm_buddy_init - init memory manager
 *
 * @mm: DRM buddy manager to initialize
 * @size: size in bytes to manage
 * @chunk_size: minimum page size in bytes for our allocations
 *
 * Initializes the memory manager and its resources.
 *
 * Returns:
 * 0 on success, error code on failure.
 */
int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size)
{
	unsigned int i;
	u64 offset;

	if (size < chunk_size)
		return -EINVAL;

	if (chunk_size < PAGE_SIZE)
		return -EINVAL;

	if (!is_power_of_2(chunk_size))
		return -EINVAL;

	size = round_down(size, chunk_size);

	mm->size = size;
	mm->avail = size;
	mm->chunk_size = chunk_size;
	mm->max_order = ilog2(size) - ilog2(chunk_size);

	BUG_ON(mm->max_order > DRM_BUDDY_MAX_ORDER);

	mm->free_list = kmalloc_array(mm->max_order + 1,
				      sizeof(struct list_head),
				      GFP_KERNEL);
	if (!mm->free_list)
		return -ENOMEM;

	for (i = 0; i <= mm->max_order; ++i)
		INIT_LIST_HEAD(&mm->free_list[i]);

	mm->n_roots = hweight64(size);

	mm->roots = kmalloc_array(mm->n_roots,
				  sizeof(struct drm_buddy_block *),
				  GFP_KERNEL);
	if (!mm->roots)
		goto out_free_list;

	offset = 0;
	i = 0;

	/*
	 * Split into power-of-two blocks, in case we are given a size that is
	 * not itself a power-of-two.
	 */
	do {
		struct drm_buddy_block *root;
		unsigned int order;
		u64 root_size;

		order = ilog2(size) - ilog2(chunk_size);
		root_size = chunk_size << order;

		root = drm_block_alloc(mm, NULL, order, offset);
		if (!root)
			goto out_free_roots;

		mark_free(mm, root);

		BUG_ON(i > mm->max_order);
		BUG_ON(drm_buddy_block_size(mm, root) < chunk_size);

		mm->roots[i] = root;

		offset += root_size;
		size -= root_size;
		i++;
	} while (size);

	return 0;

out_free_roots:
	while (i--)
		drm_block_free(mm, mm->roots[i]);
	kfree(mm->roots);
out_free_list:
	kfree(mm->free_list);
	return -ENOMEM;
}
EXPORT_SYMBOL(drm_buddy_init);

/**
 * drm_buddy_fini - tear down the memory manager
 *
 * @mm: DRM buddy manager to free
 *
 * Cleanup memory manager resources and the freelist
 */
void drm_buddy_fini(struct drm_buddy *mm)
{
	int i;

	for (i = 0; i < mm->n_roots; ++i) {
		WARN_ON(!drm_buddy_block_is_free(mm->roots[i]));
		drm_block_free(mm, mm->roots[i]);
	}

	WARN_ON(mm->avail != mm->size);

	kfree(mm->roots);
	kfree(mm->free_list);
}
EXPORT_SYMBOL(drm_buddy_fini);

static int split_block(struct drm_buddy *mm,
		       struct drm_buddy_block *block)
{
	unsigned int block_order = drm_buddy_block_order(block) - 1;
	u64 offset = drm_buddy_block_offset(block);

	BUG_ON(!drm_buddy_block_is_free(block));
	BUG_ON(!drm_buddy_block_order(block));

	block->left = drm_block_alloc(mm, block, block_order, offset);
	if (!block->left)
		return -ENOMEM;

	block->right = drm_block_alloc(mm, block, block_order,
				       offset + (mm->chunk_size << block_order));
	i