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1// SPDX-License-Identifier: GPL-2.0 OR MIT2/*3 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA4 * Copyright (c) 2012 David Airlie <airlied@linux.ie>5 * Copyright (c) 2013 David Herrmann <dh.herrmann@gmail.com>6 *7 * Permission is hereby granted, free of charge, to any person obtaining a8 * copy of this software and associated documentation files (the "Software"),9 * to deal in the Software without restriction, including without limitation10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,11 * and/or sell copies of the Software, and to permit persons to whom the12 * Software is furnished to do so, subject to the following conditions:13 *14 * The above copyright notice and this permission notice shall be included in15 * all copies or substantial portions of the Software.16 *17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL20 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR21 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,22 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR23 * OTHER DEALINGS IN THE SOFTWARE.24 */25 26#include <linux/mm.h>27#include <linux/module.h>28#include <linux/rbtree.h>29#include <linux/slab.h>30#include <linux/spinlock.h>31#include <linux/types.h>32 33#include <drm/drm_mm.h>34#include <drm/drm_vma_manager.h>35 36/**37 * DOC: vma offset manager38 *39 * The vma-manager is responsible to map arbitrary driver-dependent memory40 * regions into the linear user address-space. It provides offsets to the41 * caller which can then be used on the address_space of the drm-device. It42 * takes care to not overlap regions, size them appropriately and to not43 * confuse mm-core by inconsistent fake vm_pgoff fields.44 * Drivers shouldn't use this for object placement in VMEM. This manager should45 * only be used to manage mappings into linear user-space VMs.46 *47 * We use drm_mm as backend to manage object allocations. But it is highly48 * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to49 * speed up offset lookups.50 *51 * You must not use multiple offset managers on a single address_space.52 * Otherwise, mm-core will be unable to tear down memory mappings as the VM will53 * no longer be linear.54 *55 * This offset manager works on page-based addresses. That is, every argument56 * and return code (with the exception of drm_vma_node_offset_addr()) is given57 * in number of pages, not number of bytes. That means, object sizes and offsets58 * must always be page-aligned (as usual).59 * If you want to get a valid byte-based user-space address for a given offset,60 * please see drm_vma_node_offset_addr().61 *62 * Additionally to offset management, the vma offset manager also handles access63 * management. For every open-file context that is allowed to access a given64 * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this65 * open-file with the offset of the node will fail with -EACCES. To revoke66 * access again, use drm_vma_node_revoke(). However, the caller is responsible67 * for destroying already existing mappings, if required.68 */69 70/**71 * drm_vma_offset_manager_init - Initialize new offset-manager72 * @mgr: Manager object73 * @page_offset: Offset of available memory area (page-based)74 * @size: Size of available address space range (page-based)75 *76 * Initialize a new offset-manager. The offset and area size available for the77 * manager are given as @page_offset and @size. Both are interpreted as78 * page-numbers, not bytes.79 *80 * Adding/removing nodes from the manager is locked internally and protected81 * against concurrent access. However, node allocation and destruction is left82 * for the caller. While calling into the vma-manager, a given node must83 * always be guaranteed to be referenced.84 */85void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr,86 unsigned long page_offset, unsigned long size)87{88 rwlock_init(&mgr->vm_lock);89 drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size);90}91EXPORT_SYMBOL(drm_vma_offset_manager_init);92 93/**94 * drm_vma_offset_manager_destroy() - Destroy offset manager95 * @mgr: Manager object96 *97 * Destroy an object manager which was previously created via98 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes99 * before destroying the manager. Otherwise, drm_mm will refuse to free the100 * requested resources.101 *102 * The manager must not be accessed after this function is called.103 */104void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr)105{106 drm_mm_takedown(&mgr->vm_addr_space_mm);107}108EXPORT_SYMBOL(drm_vma_offset_manager_destroy);109 110/**111 * drm_vma_offset_lookup_locked() - Find node in offset space112 * @mgr: Manager object113 * @start: Start address for object (page-based)114 * @pages: Size of object (page-based)115 *116 * Find a node given a start address and object size. This returns the _best_117 * match for the given node. That is, @start may point somewhere into a valid118 * region and the given node will be returned, as long as the node spans the119 * whole requested area (given the size in number of pages as @pages).120 *121 * Note that before lookup the vma offset manager lookup lock must be acquired122 * with drm_vma_offset_lock_lookup(). See there for an example. This can then be123 * used to implement weakly referenced lookups using kref_get_unless_zero().124 *125 * Example:126 *127 * ::128 *129 * drm_vma_offset_lock_lookup(mgr);130 * node = drm_vma_offset_lookup_locked(mgr);131 * if (node)132 * kref_get_unless_zero(container_of(node, sth, entr));133 * drm_vma_offset_unlock_lookup(mgr);134 *135 * RETURNS:136 * Returns NULL if no suitable node can be found. Otherwise, the best match137 * is returned. It's the caller's responsibility to make sure the node doesn't138 * get destroyed before the caller can access it.139 */140struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr,141 unsigned long start,142 unsigned long pages)143{144 struct drm_mm_node *node, *best;145 struct rb_node *iter;146 unsigned long offset;147 148 iter = mgr->vm_addr_space_mm.interval_tree.rb_root.rb_node;149 best = NULL;150 151 while (likely(iter)) {152 node = rb_entry(iter, struct drm_mm_node, rb);153 offset = node->start;154 if (start >= offset) {155 iter = iter->rb_right;156 best = node;157 if (start == offset)158 break;159 } else {160 iter = iter->rb_left;161 }162 }163 164 /* verify that the node spans the requested area */165 if (best) {166 offset = best->start + best->size;167 if (offset < start + pages)168 best = NULL;169 }170 171 if (!best)172 return NULL;173 174 return container_of(best, struct drm_vma_offset_node, vm_node);175}176EXPORT_SYMBOL(drm_vma_offset_lookup_locked);177 178/**179 * drm_vma_offset_add() - Add offset node to manager180 * @mgr: Manager object181 * @node: Node to be added182 * @pages: Allocation size visible to user-space (in number of pages)183 *184 * Add a node to the offset-manager. If the node was already added, this does185 * nothing and return 0. @pages is the size of the object given in number of186 * pages.187 * After this call succeeds, you can access the offset of the node until it188 * is removed again.189 *190 * If this call fails, it is safe to retry the operation or call191 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that192 * case.193 *194 * @pages is not required to be the same size as the underlying memory object195 * that you want to map. It only limits the size that user-space can map into196 * their address space.197 *198 * RETURNS:199 * 0 on success, negative error code on failure.200 */201int drm_vma_offset_add(struct drm_vma_offset_manager *mgr,202 struct drm_vma_offset_node *node, unsigned long pages)203{204 int ret = 0;205 206 write_lock(&mgr->vm_lock);207 208 if (!drm_mm_node_allocated(&node->vm_node))209 ret = drm_mm_insert_node(&mgr->vm_addr_space_mm,210 &node->vm_node, pages);211 212 write_unlock(&mgr->vm_lock);213 214 return ret;215}216EXPORT_SYMBOL(drm_vma_offset_add);217 218/**219 * drm_vma_offset_remove() - Remove offset node from manager220 * @mgr: Manager object221 * @node: Node to be removed222 *223 * Remove a node from the offset manager. If the node wasn't added before, this224 * does nothing. After this call returns, the offset and size will be 0 until a225 * new offset is allocated via drm_vma_offset_add() again. Helper functions like226 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no227 * offset is allocated.228 */229void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,230 struct drm_vma_offset_node *node)231{232 write_lock(&mgr->vm_lock);233 234 if (drm_mm_node_allocated(&node->vm_node)) {235 drm_mm_remove_node(&node->vm_node);236 memset(&node->vm_node, 0, sizeof(node->vm_node));237 }238 239 write_unlock(&mgr->vm_lock);240}241EXPORT_SYMBOL(drm_vma_offset_remove);242 243static int vma_node_allow(struct drm_vma_offset_node *node,244 struct drm_file *tag, bool ref_counted)245{246 struct rb_node **iter;247 struct rb_node *parent = NULL;248 struct drm_vma_offset_file *new, *entry;249 int ret = 0;250 251 /* Preallocate entry to avoid atomic allocations below. It is quite252 * unlikely that an open-file is added twice to a single node so we253 * don't optimize for this case. OOM is checked below only if the entry254 * is actually used. */255 new = kmalloc(sizeof(*entry), GFP_KERNEL);256 257 write_lock(&node->vm_lock);258 259 iter = &node->vm_files.rb_node;260 261 while (likely(*iter)) {262 parent = *iter;263 entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb);264 265 if (tag == entry->vm_tag) {266 if (ref_counted)267 entry->vm_count++;268 goto unlock;269 } else if (tag > entry->vm_tag) {270 iter = &(*iter)->rb_right;271 } else {272 iter = &(*iter)->rb_left;273 }274 }275 276 if (!new) {277 ret = -ENOMEM;278 goto unlock;279 }280 281 new->vm_tag = tag;282 new->vm_count = 1;283 rb_link_node(&new->vm_rb, parent, iter);284 rb_insert_color(&new->vm_rb, &node->vm_files);285 new = NULL;286 287unlock:288 write_unlock(&node->vm_lock);289 kfree(new);290 return ret;291}292 293/**294 * drm_vma_node_allow - Add open-file to list of allowed users295 * @node: Node to modify296 * @tag: Tag of file to remove297 *298 * Add @tag to the list of allowed open-files for this node. If @tag is299 * already on this list, the ref-count is incremented.300 *301 * The list of allowed-users is preserved across drm_vma_offset_add() and302 * drm_vma_offset_remove() calls. You may even call it if the node is currently303 * not added to any offset-manager.304 *305 * You must remove all open-files the same number of times as you added them306 * before destroying the node. Otherwise, you will leak memory.307 *308 * This is locked against concurrent access internally.309 *310 * RETURNS:311 * 0 on success, negative error code on internal failure (out-of-mem)312 */313int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag)314{315 return vma_node_allow(node, tag, true);316}317EXPORT_SYMBOL(drm_vma_node_allow);318 319/**320 * drm_vma_node_allow_once - Add open-file to list of allowed users321 * @node: Node to modify322 * @tag: Tag of file to remove323 *324 * Add @tag to the list of allowed open-files for this node.325 *326 * The list of allowed-users is preserved across drm_vma_offset_add() and327 * drm_vma_offset_remove() calls. You may even call it if the node is currently328 * not added to any offset-manager.329 *330 * This is not ref-counted unlike drm_vma_node_allow() hence drm_vma_node_revoke()331 * should only be called once after this.332 *333 * This is locked against concurrent access internally.334 *335 * RETURNS:336 * 0 on success, negative error code on internal failure (out-of-mem)337 */338int drm_vma_node_allow_once(struct drm_vma_offset_node *node, struct drm_file *tag)339{340 return vma_node_allow(node, tag, false);341}342EXPORT_SYMBOL(drm_vma_node_allow_once);343 344/**345 * drm_vma_node_revoke - Remove open-file from list of allowed users346 * @node: Node to modify347 * @tag: Tag of file to remove348 *349 * Decrement the ref-count of @tag in the list of allowed open-files on @node.350 * If the ref-count drops to zero, remove @tag from the list. You must call351 * this once for every drm_vma_node_allow() on @tag.352 *353 * This is locked against concurrent access internally.354 *355 * If @tag is not on the list, nothing is done.356 */357void drm_vma_node_revoke(struct drm_vma_offset_node *node,358 struct drm_file *tag)359{360 struct drm_vma_offset_file *entry;361 struct rb_node *iter;362 363 write_lock(&node->vm_lock);364 365 iter = node->vm_files.rb_node;366 while (likely(iter)) {367 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);368 if (tag == entry->vm_tag) {369 if (!--entry->vm_count) {370 rb_erase(&entry->vm_rb, &node->vm_files);371 kfree(entry);372 }373 break;374 } else if (tag > entry->vm_tag) {375 iter = iter->rb_right;376 } else {377 iter = iter->rb_left;378 }379 }380 381 write_unlock(&node->vm_lock);382}383EXPORT_SYMBOL(drm_vma_node_revoke);384 385/**386 * drm_vma_node_is_allowed - Check whether an open-file is granted access387 * @node: Node to check388 * @tag: Tag of file to remove389 *390 * Search the list in @node whether @tag is currently on the list of allowed391 * open-files (see drm_vma_node_allow()).392 *393 * This is locked against concurrent access internally.394 *395 * RETURNS:396 * true if @filp is on the list397 */398bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node,399 struct drm_file *tag)400{401 struct drm_vma_offset_file *entry;402 struct rb_node *iter;403 404 read_lock(&node->vm_lock);405 406 iter = node->vm_files.rb_node;407 while (likely(iter)) {408 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);409 if (tag == entry->vm_tag)410 break;411 else if (tag > entry->vm_tag)412 iter = iter->rb_right;413 else414 iter = iter->rb_left;415 }416 417 read_unlock(&node->vm_lock);418 419 return iter;420}421EXPORT_SYMBOL(drm_vma_node_is_allowed);422