1/* 2 * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA 3 * Copyright (c) 2012 David Airlie <airlied@linux.ie> 4 * Copyright (c) 2013 David Herrmann <dh.herrmann@gmail.com> 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a 7 * copy of this software and associated documentation files (the "Software"), 8 * to deal in the Software without restriction, including without limitation 9 * the rights to use, copy, modify, merge, publish, distribute, sublicense, 10 * and/or sell copies of the Software, and to permit persons to whom the 11 * Software is furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR 20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 22 * OTHER DEALINGS IN THE SOFTWARE. 23 */ 24 25#include <drm/drmP.h> 26#include <drm/drm_mm.h> 27#include <drm/drm_vma_manager.h> 28#include <linux/fs.h> 29#include <linux/mm.h> 30#include <linux/module.h> 31#include <linux/rbtree.h> 32#include <linux/slab.h> 33#include <linux/spinlock.h> 34#include <linux/types.h> 35 36/** 37 * DOC: vma offset manager 38 * 39 * The vma-manager is responsible to map arbitrary driver-dependent memory 40 * regions into the linear user address-space. It provides offsets to the 41 * caller which can then be used on the address_space of the drm-device. It 42 * takes care to not overlap regions, size them appropriately and to not 43 * confuse mm-core by inconsistent fake vm_pgoff fields. 44 * Drivers shouldn't use this for object placement in VMEM. This manager should 45 * 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 highly 48 * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to 49 * 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 will 53 * no longer be linear. 54 * 55 * This offset manager works on page-based addresses. That is, every argument 56 * and return code (with the exception of drm_vma_node_offset_addr()) is given 57 * in number of pages, not number of bytes. That means, object sizes and offsets 58 * 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 access 63 * management. For every open-file context that is allowed to access a given 64 * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this 65 * open-file with the offset of the node will fail with -EACCES. To revoke 66 * access again, use drm_vma_node_revoke(). However, the caller is responsible 67 * for destroying already existing mappings, if required. 68 */ 69 70/** 71 * drm_vma_offset_manager_init - Initialize new offset-manager 72 * @mgr: Manager object 73 * @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 the 77 * manager are given as @page_offset and @size. Both are interpreted as 78 * page-numbers, not bytes. 79 * 80 * Adding/removing nodes from the manager is locked internally and protected 81 * against concurrent access. However, node allocation and destruction is left 82 * for the caller. While calling into the vma-manager, a given node must 83 * 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 mgr->vm_addr_space_rb = RB_ROOT; 90 drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size); 91} 92EXPORT_SYMBOL(drm_vma_offset_manager_init); 93 94/** 95 * drm_vma_offset_manager_destroy() - Destroy offset manager 96 * @mgr: Manager object 97 * 98 * Destroy an object manager which was previously created via 99 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes 100 * before destroying the manager. Otherwise, drm_mm will refuse to free the 101 * requested resources. 102 * 103 * The manager must not be accessed after this function is called. 104 */ 105void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr) 106{ 107 /* take the lock to protect against buggy drivers */ 108 write_lock(&mgr->vm_lock); 109 drm_mm_takedown(&mgr->vm_addr_space_mm); 110 write_unlock(&mgr->vm_lock); 111} 112EXPORT_SYMBOL(drm_vma_offset_manager_destroy); 113 114/** 115 * drm_vma_offset_lookup() - Find node in offset space 116 * @mgr: Manager object 117 * @start: Start address for object (page-based) 118 * @pages: Size of object (page-based) 119 * 120 * Find a node given a start address and object size. This returns the _best_ 121 * match for the given node. That is, @start may point somewhere into a valid 122 * region and the given node will be returned, as long as the node spans the 123 * whole requested area (given the size in number of pages as @pages). 124 * 125 * RETURNS: 126 * Returns NULL if no suitable node can be found. Otherwise, the best match 127 * is returned. It's the caller's responsibility to make sure the node doesn't 128 * get destroyed before the caller can access it. 129 */ 130struct drm_vma_offset_node *drm_vma_offset_lookup(struct drm_vma_offset_manager *mgr, 131 unsigned long start, 132 unsigned long pages) 133{ 134 struct drm_vma_offset_node *node; 135 136 read_lock(&mgr->vm_lock); 137 node = drm_vma_offset_lookup_locked(mgr, start, pages); 138 read_unlock(&mgr->vm_lock); 139 140 return node; 141} 142EXPORT_SYMBOL(drm_vma_offset_lookup); 143 144/** 145 * drm_vma_offset_lookup_locked() - Find node in offset space 146 * @mgr: Manager object 147 * @start: Start address for object (page-based) 148 * @pages: Size of object (page-based) 149 * 150 * Same as drm_vma_offset_lookup() but requires the caller to lock offset lookup 151 * manually. See drm_vma_offset_lock_lookup() for an example. 152 * 153 * RETURNS: 154 * Returns NULL if no suitable node can be found. Otherwise, the best match 155 * is returned. 156 */ 157struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr, 158 unsigned long start, 159 unsigned long pages) 160{ 161 struct drm_vma_offset_node *node, *best; 162 struct rb_node *iter; 163 unsigned long offset; 164 165 iter = mgr->vm_addr_space_rb.rb_node; 166 best = NULL; 167 168 while (likely(iter)) { 169 node = rb_entry(iter, struct drm_vma_offset_node, vm_rb); 170 offset = node->vm_node.start; 171 if (start >= offset) { 172 iter = iter->rb_right; 173 best = node; 174 if (start == offset) 175 break; 176 } else { 177 iter = iter->rb_left; 178 } 179 } 180 181 /* verify that the node spans the requested area */ 182 if (best) { 183 offset = best->vm_node.start + best->vm_node.size; 184 if (offset < start + pages) 185 best = NULL; 186 } 187 188 return best; 189} 190EXPORT_SYMBOL(drm_vma_offset_lookup_locked); 191 192/* internal helper to link @node into the rb-tree */ 193static void _drm_vma_offset_add_rb(struct drm_vma_offset_manager *mgr, 194 struct drm_vma_offset_node *node) 195{ 196 struct rb_node **iter = &mgr->vm_addr_space_rb.rb_node; 197 struct rb_node *parent = NULL; 198 struct drm_vma_offset_node *iter_node; 199 200 while (likely(*iter)) { 201 parent = *iter; 202 iter_node = rb_entry(*iter, struct drm_vma_offset_node, vm_rb); 203 204 if (node->vm_node.start < iter_node->vm_node.start) 205 iter = &(*iter)->rb_left; 206 else if (node->vm_node.start > iter_node->vm_node.start) 207 iter = &(*iter)->rb_right; 208 else 209 BUG(); 210 } 211 212 rb_link_node(&node->vm_rb, parent, iter); 213 rb_insert_color(&node->vm_rb, &mgr->vm_addr_space_rb); 214} 215 216/** 217 * drm_vma_offset_add() - Add offset node to manager 218 * @mgr: Manager object 219 * @node: Node to be added 220 * @pages: Allocation size visible to user-space (in number of pages) 221 * 222 * Add a node to the offset-manager. If the node was already added, this does 223 * nothing and return 0. @pages is the size of the object given in number of 224 * pages. 225 * After this call succeeds, you can access the offset of the node until it 226 * is removed again. 227 * 228 * If this call fails, it is safe to retry the operation or call 229 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that 230 * case. 231 * 232 * @pages is not required to be the same size as the underlying memory object 233 * that you want to map. It only limits the size that user-space can map into 234 * their address space. 235 * 236 * RETURNS: 237 * 0 on success, negative error code on failure. 238 */ 239int drm_vma_offset_add(struct drm_vma_offset_manager *mgr, 240 struct drm_vma_offset_node *node, unsigned long pages) 241{ 242 int ret; 243 244 write_lock(&mgr->vm_lock); 245 246 if (drm_mm_node_allocated(&node->vm_node)) { 247 ret = 0; 248 goto out_unlock; 249 } 250 251 ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node, 252 pages, 0, DRM_MM_SEARCH_DEFAULT); 253 if (ret) 254 goto out_unlock; 255 256 _drm_vma_offset_add_rb(mgr, node); 257 258out_unlock: 259 write_unlock(&mgr->vm_lock); 260 return ret; 261} 262EXPORT_SYMBOL(drm_vma_offset_add); 263 264/** 265 * drm_vma_offset_remove() - Remove offset node from manager 266 * @mgr: Manager object 267 * @node: Node to be removed 268 * 269 * Remove a node from the offset manager. If the node wasn't added before, this 270 * does nothing. After this call returns, the offset and size will be 0 until a 271 * new offset is allocated via drm_vma_offset_add() again. Helper functions like 272 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no 273 * offset is allocated. 274 */ 275void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr, 276 struct drm_vma_offset_node *node) 277{ 278 write_lock(&mgr->vm_lock); 279 280 if (drm_mm_node_allocated(&node->vm_node)) { 281 rb_erase(&node->vm_rb, &mgr->vm_addr_space_rb); 282 drm_mm_remove_node(&node->vm_node); 283 memset(&node->vm_node, 0, sizeof(node->vm_node)); 284 } 285 286 write_unlock(&mgr->vm_lock); 287} 288EXPORT_SYMBOL(drm_vma_offset_remove); 289 290/** 291 * drm_vma_node_allow - Add open-file to list of allowed users 292 * @node: Node to modify 293 * @filp: Open file to add 294 * 295 * Add @filp to the list of allowed open-files for this node. If @filp is 296 * already on this list, the ref-count is incremented. 297 * 298 * The list of allowed-users is preserved across drm_vma_offset_add() and 299 * drm_vma_offset_remove() calls. You may even call it if the node is currently 300 * not added to any offset-manager. 301 * 302 * You must remove all open-files the same number of times as you added them 303 * before destroying the node. Otherwise, you will leak memory. 304 * 305 * This is locked against concurrent access internally. 306 * 307 * RETURNS: 308 * 0 on success, negative error code on internal failure (out-of-mem) 309 */ 310int drm_vma_node_allow(struct drm_vma_offset_node *node, struct file *filp) 311{ 312 struct rb_node **iter; 313 struct rb_node *parent = NULL; 314 struct drm_vma_offset_file *new, *entry; 315 int ret = 0; 316 317 /* Preallocate entry to avoid atomic allocations below. It is quite 318 * unlikely that an open-file is added twice to a single node so we 319 * don't optimize for this case. OOM is checked below only if the entry 320 * is actually used. */ 321 new = kmalloc(sizeof(*entry), GFP_KERNEL); 322 323 write_lock(&node->vm_lock); 324 325 iter = &node->vm_files.rb_node; 326 327 while (likely(*iter)) { 328 parent = *iter; 329 entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb); 330 331 if (filp == entry->vm_filp) { 332 entry->vm_count++; 333 goto unlock; 334 } else if (filp > entry->vm_filp) { 335 iter = &(*iter)->rb_right; 336 } else { 337 iter = &(*iter)->rb_left; 338 } 339 } 340 341 if (!new) { 342 ret = -ENOMEM; 343 goto unlock; 344 } 345 346 new->vm_filp = filp; 347 new->vm_count = 1; 348 rb_link_node(&new->vm_rb, parent, iter); 349 rb_insert_color(&new->vm_rb, &node->vm_files); 350 new = NULL; 351 352unlock: 353 write_unlock(&node->vm_lock); 354 kfree(new); 355 return ret; 356} 357EXPORT_SYMBOL(drm_vma_node_allow); 358 359/** 360 * drm_vma_node_revoke - Remove open-file from list of allowed users 361 * @node: Node to modify 362 * @filp: Open file to remove 363 * 364 * Decrement the ref-count of @filp in the list of allowed open-files on @node. 365 * If the ref-count drops to zero, remove @filp from the list. You must call 366 * this once for every drm_vma_node_allow() on @filp. 367 * 368 * This is locked against concurrent access internally. 369 * 370 * If @filp is not on the list, nothing is done. 371 */ 372void drm_vma_node_revoke(struct drm_vma_offset_node *node, struct file *filp) 373{ 374 struct drm_vma_offset_file *entry; 375 struct rb_node *iter; 376 377 write_lock(&node->vm_lock); 378 379 iter = node->vm_files.rb_node; 380 while (likely(iter)) { 381 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb); 382 if (filp == entry->vm_filp) { 383 if (!--entry->vm_count) { 384 rb_erase(&entry->vm_rb, &node->vm_files); 385 kfree(entry); 386 } 387 break; 388 } else if (filp > entry->vm_filp) { 389 iter = iter->rb_right; 390 } else { 391 iter = iter->rb_left; 392 } 393 } 394 395 write_unlock(&node->vm_lock); 396} 397EXPORT_SYMBOL(drm_vma_node_revoke); 398 399/** 400 * drm_vma_node_is_allowed - Check whether an open-file is granted access 401 * @node: Node to check 402 * @filp: Open-file to check for 403 * 404 * Search the list in @node whether @filp is currently on the list of allowed 405 * open-files (see drm_vma_node_allow()). 406 * 407 * This is locked against concurrent access internally. 408 * 409 * RETURNS: 410 * true iff @filp is on the list 411 */ 412bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node, 413 struct file *filp) 414{ 415 struct drm_vma_offset_file *entry; 416 struct rb_node *iter; 417 418 read_lock(&node->vm_lock); 419 420 iter = node->vm_files.rb_node; 421 while (likely(iter)) { 422 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb); 423 if (filp == entry->vm_filp) 424 break; 425 else if (filp > entry->vm_filp) 426 iter = iter->rb_right; 427 else 428 iter = iter->rb_left; 429 } 430 431 read_unlock(&node->vm_lock); 432 433 return iter; 434} 435EXPORT_SYMBOL(drm_vma_node_is_allowed); 436