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/*

 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA

 * Copyright (c) 2012 David Airlie 

 * Copyright (c) 2013 David Herrmann 

 *

 * 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 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 COPYRIGHT HOLDER(S) OR AUTHOR(S) 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.

 */

#include 

#include 

#include 

#include 

#include 

#include 

#include 

#include 

#include 

#include 

/**

 * DOC: vma offset manager

 *

 * The vma-manager is responsible to map arbitrary driver-dependent memory

 * regions into the linear user address-space. It provides offsets to the

 * caller which can then be used on the address_space of the drm-device. It

 * takes care to not overlap regions, size them appropriately and to not

 * confuse mm-core by inconsistent fake vm_pgoff fields.

 * Drivers shouldn't use this for object placement in VMEM. This manager should

 * only be used to manage mappings into linear user-space VMs.

 *

 * We use drm_mm as backend to manage object allocations. But it is highly

 * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to

 * speed up offset lookups.

 *

 * You must not use multiple offset managers on a single address_space.

 * Otherwise, mm-core will be unable to tear down memory mappings as the VM will

 * no longer be linear.

 *

 * This offset manager works on page-based addresses. That is, every argument

 * and return code (with the exception of drm_vma_node_offset_addr()) is given

 * in number of pages, not number of bytes. That means, object sizes and offsets

 * must always be page-aligned (as usual).

 * If you want to get a valid byte-based user-space address for a given offset,

 * please see drm_vma_node_offset_addr().

 *

 * Additionally to offset management, the vma offset manager also handles access

 * management. For every open-file context that is allowed to access a given

 * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this

 * open-file with the offset of the node will fail with -EACCES. To revoke

 * access again, use drm_vma_node_revoke(). However, the caller is responsible

 * for destroying already existing mappings, if required.

 */

/**

 * drm_vma_offset_manager_init - Initialize new offset-manager

 * @mgr: Manager object

 * @page_offset: Offset of available memory area (page-based)

 * @size: Size of available address space range (page-based)

 *

 * Initialize a new offset-manager. The offset and area size available for the

 * manager are given as @page_offset and @size. Both are interpreted as

 * page-numbers, not bytes.

 *

 * Adding/removing nodes from the manager is locked internally and protected

 * against concurrent access. However, node allocation and destruction is left

 * for the caller. While calling into the vma-manager, a given node must

 * always be guaranteed to be referenced.

 */

void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr,

				 unsigned long page_offset, unsigned long size)

{

	rwlock_init(&mgr->vm_lock);

	mgr->vm_addr_space_rb = RB_ROOT;

	drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size);

}

EXPORT_SYMBOL(drm_vma_offset_manager_init);

/**

 * drm_vma_offset_manager_destroy() - Destroy offset manager

 * @mgr: Manager object

 *

 * Destroy an object manager which was previously created via

 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes

 * before destroying the manager. Otherwise, drm_mm will refuse to free the

 * requested resources.

 *

 * The manager must not be accessed after this function is called.

 */

void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr)

{

	/* take the lock to protect against buggy drivers */

	write_lock(&mgr->vm_lock);

	drm_mm_takedown(&mgr->vm_addr_space_mm);

	write_unlock(&mgr->vm_lock);

}

EXPORT_SYMBOL(drm_vma_offset_manager_destroy);

/**

 * drm_vma_offset_lookup_locked() - Find node in offset space

 * @mgr: Manager object

 * @start: Start address for object (page-based)

 * @pages: Size of object (page-based)

 *

 * Find a node given a start address and object size. This returns the _best_

 * match for the given node. That is, @start may point somewhere into a valid

 * region and the given node will be returned, as long as the node spans the

 * whole requested area (given the size in number of pages as @pages).

 *

 * Note that before lookup the vma offset manager lookup lock must be acquired

 * with drm_vma_offset_lock_lookup(). See there for an example. This can then be

 * used to implement weakly referenced lookups using kref_get_unless_zero().

 *

 * Example:

 *     drm_vma_offset_lock_lookup(mgr);

 *     node = drm_vma_offset_lookup_locked(mgr);

 *     if (node)

 *         kref_get_unless_zero(container_of(node, sth, entr));

 *     drm_vma_offset_unlock_lookup(mgr);

 *

 * RETURNS:

 * Returns NULL if no suitable node can be found. Otherwise, the best match

 * is returned. It's the caller's responsibility to make sure the node doesn't

 * get destroyed before the caller can access it.

 */

struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr,

							 unsigned long start,

							 unsigned long pages)

{

	struct drm_vma_offset_node *node, *best;

	struct rb_node *iter;

	unsigned long offset;

	iter = mgr->vm_addr_space_rb.rb_node;

	best = NULL;

	while (likely(iter)) {

		node = rb_entry(iter, struct drm_vma_offset_node, vm_rb);

		offset = node->vm_node.start;

		if (start >= offset) {

			iter = iter->rb_right;

			best = node;

			if (start == offset)

				break;

		} else {

			iter = iter->rb_left;

		}

	}

	/* verify that the node spans the requested area */

	if (best) {

		offset = best->vm_node.start + best->vm_node.size;

		if (offset < start + pages)

			best = NULL;

	}

	return best;

}

EXPORT_SYMBOL(drm_vma_offset_lookup_locked);

/* internal helper to link @node into the rb-tree */

static void _drm_vma_offset_add_rb(struct drm_vma_offset_manager *mgr,

				   struct drm_vma_offset_node *node)

{

	struct rb_node **iter = &mgr->vm_addr_space_rb.rb_node;

	struct rb_node *parent = NULL;

	struct drm_vma_offset_node *iter_node;

	while (likely(*iter)) {

		parent = *iter;

		iter_node = rb_entry(*iter, struct drm_vma_offset_node, vm_rb);

		if (node->vm_node.start < iter_node->vm_node.start)

			iter = &(*iter)->rb_left;

		else if (node->vm_node.start > iter_node->vm_node.start)

			iter = &(*iter)->rb_right;

		else

			BUG();

	}

	rb_link_node(&node->vm_rb, parent, iter);

	rb_insert_color(&node->vm_rb, &mgr->vm_addr_space_rb);

}

/**

 * drm_vma_offset_add() - Add offset node to manager

 * @mgr: Manager object

 * @node: Node to be added

 * @pages: Allocation size visible to user-space (in number of pages)

 *

 * Add a node to the offset-manager. If the node was already added, this does

 * nothing and return 0. @pages is the size of the object given in number of

 * pages.

 * After this call succeeds, you can access the offset of the node until it

 * is removed again.

 *

 * If this call fails, it is safe to retry the operation or call

 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that

 * case.

 *

 * @pages is not required to be the same size as the underlying memory object

 * that you want to map. It only limits the size that user-space can map into

 * their address space.

 *

 * RETURNS:

 * 0 on success, negative error code on failure.

 */

int drm_vma_offset_add(struct drm_vma_offset_manager *mgr,

		       struct drm_vma_offset_node *node, unsigned long pages)

{

	int ret;

	write_lock(&mgr->vm_lock);

	if (drm_mm_node_allocated(&node->vm_node)) {

		ret = 0;

		goto out_unlock;

	}

	ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node,

				 pages, 0, DRM_MM_SEARCH_DEFAULT);

	if (ret)

		goto out_unlock;

	_drm_vma_offset_add_rb(mgr, node);

out_unlock:

	write_unlock(&mgr->vm_lock);

	return ret;

}

EXPORT_SYMBOL(drm_vma_offset_add);

/**

 * drm_vma_offset_remove() - Remove offset node from manager

 * @mgr: Manager object

 * @node: Node to be removed

 *

 * Remove a node from the offset manager. If the node wasn't added before, this

 * does nothing. After this call returns, the offset and size will be 0 until a

 * new offset is allocated via drm_vma_offset_add() again. Helper functions like

 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no

 * offset is allocated.

 */

void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,

			   struct drm_vma_offset_node *node)

{

	write_lock(&mgr->vm_lock);

	if (drm_mm_node_allocated(&node->vm_node)) {

		rb_erase(&node->vm_rb, &mgr->vm_addr_space_rb);

		drm_mm_remove_node(&node->vm_node);

		memset(&node->vm_node, 0, sizeof(node->vm_node));

	}

	write_unlock(&mgr->vm_lock);

}

EXPORT_SYMBOL(drm_vma_offset_remove);

/**

 * drm_vma_node_allow - Add open-file to list of allowed users

 * @node: Node to modify

 * @filp: Open file to add

 *

 * Add @filp to the list of allowed open-files for this node. If @filp is

 * already on this list, the ref-count is incremented.

 *

 * The list of allowed-users is preserved across drm_vma_offset_add() and

 * drm_vma_offset_remove() calls. You may even call it if the node is currently

 * not added to any offset-manager.

 *

 * You must remove all open-files the same number of times as you added them

 * before destroying the node. Otherwise, you will leak memory.

 *

 * This is locked against concurrent access internally.

 *

 * RETURNS:

 * 0 on success, negative error code on internal failure (out-of-mem)

 */

int drm_vma_node_allow(struct drm_vma_offset_node *node, struct file *filp)

{

	struct rb_node **iter;

	struct rb_node *parent = NULL;

	struct drm_vma_offset_file *new, *entry;

	int ret = 0;

	/* Preallocate entry to avoid atomic allocations below. It is quite

	 * unlikely that an open-file is added twice to a single node so we

	 * don't optimize for this case. OOM is checked below only if the entry

	 * is actually used. */

	new = kmalloc(sizeof(*entry), GFP_KERNEL);

	write_lock(&node->vm_lock);

	iter = &node->vm_files.rb_node;

	while (likely(*iter)) {

		parent = *iter;

		entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb);

		if (filp == entry->vm_filp) {

			entry->vm_count++;

			goto unlock;

		} else if (filp > entry->vm_filp) {

			iter = &(*iter)->rb_right;

		} else {

			iter = &(*iter)->rb_left;

		}

	}

	if (!new) {

		ret = -ENOMEM;

		goto unlock;

	}

	new->vm_filp = filp;

	new->vm_count = 1;

	rb_link_node(&new->vm_rb, parent, iter);

	rb_insert_color(&new->vm_rb, &node->vm_files);

	new = NULL;

unlock:

	write_unlock(&node->vm_lock);

	kfree(new);

	return ret;

}

EXPORT_SYMBOL(drm_vma_node_allow);

/**

 * drm_vma_node_revoke - Remove open-file from list of allowed users

 * @node: Node to modify

 * @filp: Open file to remove

 *

 * Decrement the ref-count of @filp in the list of allowed open-files on @node.

 * If the ref-count drops to zero, remove @filp from the list. You must call

 * this once for every drm_vma_node_allow() on @filp.

 *

 * This is locked against concurrent access internally.

 *

 * If @filp is not on the list, nothing is done.

 */

void drm_vma_node_revoke(struct drm_vma_offset_node *node, struct file *filp)

{

	struct drm_vma_offset_file *entry;

	struct rb_node *iter;

	write_lock(&node->vm_lock);

	iter = node->vm_files.rb_node;

	while (likely(iter)) {

		entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);

		if (filp == entry->vm_filp) {

			if (!--entry->vm_count) {

				rb_erase(&entry->vm_rb, &node->vm_files);

				kfree(entry);

			}

			break;

		} else if (filp > entry->vm_filp) {

			iter = iter->rb_right;

		} else {

			iter = iter->rb_left;

		}

	}

	write_unlock(&node->vm_lock);

}

EXPORT_SYMBOL(drm_vma_node_revoke);

/**

 * drm_vma_node_is_allowed - Check whether an open-file is granted access

 * @node: Node to check

 * @filp: Open-file to check for

 *

 * Search the list in @node whether @filp is currently on the list of allowed

 * open-files (see drm_vma_node_allow()).

 *

 * This is locked against concurrent access internally.

 *

 * RETURNS:

 * true iff @filp is on the list

 */

bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node,

			     struct file *filp)

{

	struct drm_vma_offset_file *entry;

	struct rb_node *iter;

	read_lock(&node->vm_lock);

	iter = node->vm_files.rb_node;

	while (likely(iter)) {

		entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);

		if (filp == entry->vm_filp)

			break;

		else if (filp > entry->vm_filp)

			iter = iter->rb_right;

		else

			iter = iter->rb_left;

	}

	read_unlock(&node->vm_lock);

	return iter;

}

EXPORT_SYMBOL(drm_vma_node_is_allowed);