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. Please use VM_NONLINEAR in that case and implement your 54 * own offset managers. 55 * 56 * This offset manager works on page-based addresses. That is, every argument 57 * and return code (with the exception of drm_vma_node_offset_addr()) is given 58 * in number of pages, not number of bytes. That means, object sizes and offsets 59 * must always be page-aligned (as usual). 60 * If you want to get a valid byte-based user-space address for a given offset, 61 * please see drm_vma_node_offset_addr(). 62 * 63 * Additionally to offset management, the vma offset manager also handles access 64 * management. For every open-file context that is allowed to access a given 65 * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this 66 * open-file with the offset of the node will fail with -EACCES. To revoke 67 * access again, use drm_vma_node_revoke(). However, the caller is responsible 68 * for destroying already existing mappings, if required. 69 */ 70 71/** 72 * drm_vma_offset_manager_init - Initialize new offset-manager 73 * @mgr: Manager object 74 * @page_offset: Offset of available memory area (page-based) 75 * @size: Size of available address space range (page-based) 76 * 77 * Initialize a new offset-manager. The offset and area size available for the 78 * manager are given as @page_offset and @size. Both are interpreted as 79 * page-numbers, not bytes. 80 * 81 * Adding/removing nodes from the manager is locked internally and protected 82 * against concurrent access. However, node allocation and destruction is left 83 * for the caller. While calling into the vma-manager, a given node must 84 * always be guaranteed to be referenced. 85 */ 86void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr, 87 unsigned long page_offset, unsigned long size) 88{ 89 rwlock_init(&mgr->vm_lock); 90 mgr->vm_addr_space_rb = RB_ROOT; 91 drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size); 92} 93EXPORT_SYMBOL(drm_vma_offset_manager_init); 94 95/** 96 * drm_vma_offset_manager_destroy() - Destroy offset manager 97 * @mgr: Manager object 98 * 99 * Destroy an object manager which was previously created via 100 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes 101 * before destroying the manager. Otherwise, drm_mm will refuse to free the 102 * requested resources. 103 * 104 * The manager must not be accessed after this function is called. 105 */ 106void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr) 107{ 108 /* take the lock to protect against buggy drivers */ 109 write_lock(&mgr->vm_lock); 110 drm_mm_takedown(&mgr->vm_addr_space_mm); 111 write_unlock(&mgr->vm_lock); 112} 113EXPORT_SYMBOL(drm_vma_offset_manager_destroy); 114 115/** 116 * drm_vma_offset_lookup() - Find node in offset space 117 * @mgr: Manager object 118 * @start: Start address for object (page-based) 119 * @pages: Size of object (page-based) 120 * 121 * Find a node given a start address and object size. This returns the _best_ 122 * match for the given node. That is, @start may point somewhere into a valid 123 * region and the given node will be returned, as long as the node spans the 124 * whole requested area (given the size in number of pages as @pages). 125 * 126 * RETURNS: 127 * Returns NULL if no suitable node can be found. Otherwise, the best match 128 * is returned. It's the caller's responsibility to make sure the node doesn't 129 * get destroyed before the caller can access it. 130 */ 131struct drm_vma_offset_node *drm_vma_offset_lookup(struct drm_vma_offset_manager *mgr, 132 unsigned long start, 133 unsigned long pages) 134{ 135 struct drm_vma_offset_node *node; 136 137 read_lock(&mgr->vm_lock); 138 node = drm_vma_offset_lookup_locked(mgr, start, pages); 139 read_unlock(&mgr->vm_lock); 140 141 return node; 142} 143EXPORT_SYMBOL(drm_vma_offset_lookup); 144 145/** 146 * drm_vma_offset_lookup_locked() - Find node in offset space 147 * @mgr: Manager object 148 * @start: Start address for object (page-based) 149 * @pages: Size of object (page-based) 150 * 151 * Same as drm_vma_offset_lookup() but requires the caller to lock offset lookup 152 * manually. See drm_vma_offset_lock_lookup() for an example. 153 * 154 * RETURNS: 155 * Returns NULL if no suitable node can be found. Otherwise, the best match 156 * is returned. 157 */ 158struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr, 159 unsigned long start, 160 unsigned long pages) 161{ 162 struct drm_vma_offset_node *node, *best; 163 struct rb_node *iter; 164 unsigned long offset; 165 166 iter = mgr->vm_addr_space_rb.rb_node; 167 best = NULL; 168 169 while (likely(iter)) { 170 node = rb_entry(iter, struct drm_vma_offset_node, vm_rb); 171 offset = node->vm_node.start; 172 if (start >= offset) { 173 iter = iter->rb_right; 174 best = node; 175 if (start == offset) 176 break; 177 } else { 178 iter = iter->rb_left; 179 } 180 } 181 182 /* verify that the node spans the requested area */ 183 if (best) { 184 offset = best->vm_node.start + best->vm_node.size; 185 if (offset < start + pages) 186 best = NULL; 187 } 188 189 return best; 190} 191EXPORT_SYMBOL(drm_vma_offset_lookup_locked); 192 193/* internal helper to link @node into the rb-tree */ 194static void _drm_vma_offset_add_rb(struct drm_vma_offset_manager *mgr, 195 struct drm_vma_offset_node *node) 196{ 197 struct rb_node **iter = &mgr->vm_addr_space_rb.rb_node; 198 struct rb_node *parent = NULL; 199 struct drm_vma_offset_node *iter_node; 200 201 while (likely(*iter)) { 202 parent = *iter; 203 iter_node = rb_entry(*iter, struct drm_vma_offset_node, vm_rb); 204 205 if (node->vm_node.start < iter_node->vm_node.start) 206 iter = &(*iter)->rb_left; 207 else if (node->vm_node.start > iter_node->vm_node.start) 208 iter = &(*iter)->rb_right; 209 else 210 BUG(); 211 } 212 213 rb_link_node(&node->vm_rb, parent, iter); 214 rb_insert_color(&node->vm_rb, &mgr->vm_addr_space_rb); 215} 216 217/** 218 * drm_vma_offset_add() - Add offset node to manager 219 * @mgr: Manager object 220 * @node: Node to be added 221 * @pages: Allocation size visible to user-space (in number of pages) 222 * 223 * Add a node to the offset-manager. If the node was already added, this does 224 * nothing and return 0. @pages is the size of the object given in number of 225 * pages. 226 * After this call succeeds, you can access the offset of the node until it 227 * is removed again. 228 * 229 * If this call fails, it is safe to retry the operation or call 230 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that 231 * case. 232 * 233 * @pages is not required to be the same size as the underlying memory object 234 * that you want to map. It only limits the size that user-space can map into 235 * their address space. 236 * 237 * RETURNS: 238 * 0 on success, negative error code on failure. 239 */ 240int drm_vma_offset_add(struct drm_vma_offset_manager *mgr, 241 struct drm_vma_offset_node *node, unsigned long pages) 242{ 243 int ret; 244 245 write_lock(&mgr->vm_lock); 246 247 if (drm_mm_node_allocated(&node->vm_node)) { 248 ret = 0; 249 goto out_unlock; 250 } 251 252 ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node, 253 pages, 0, DRM_MM_SEARCH_DEFAULT); 254 if (ret) 255 goto out_unlock; 256 257 _drm_vma_offset_add_rb(mgr, node); 258 259out_unlock: 260 write_unlock(&mgr->vm_lock); 261 return ret; 262} 263EXPORT_SYMBOL(drm_vma_offset_add); 264 265/** 266 * drm_vma_offset_remove() - Remove offset node from manager 267 * @mgr: Manager object 268 * @node: Node to be removed 269 * 270 * Remove a node from the offset manager. If the node wasn't added before, this 271 * does nothing. After this call returns, the offset and size will be 0 until a 272 * new offset is allocated via drm_vma_offset_add() again. Helper functions like 273 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no 274 * offset is allocated. 275 */ 276void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr, 277 struct drm_vma_offset_node *node) 278{ 279 write_lock(&mgr->vm_lock); 280 281 if (drm_mm_node_allocated(&node->vm_node)) { 282 rb_erase(&node->vm_rb, &mgr->vm_addr_space_rb); 283 drm_mm_remove_node(&node->vm_node); 284 memset(&node->vm_node, 0, sizeof(node->vm_node)); 285 } 286 287 write_unlock(&mgr->vm_lock); 288} 289EXPORT_SYMBOL(drm_vma_offset_remove); 290 291/** 292 * drm_vma_node_allow - Add open-file to list of allowed users 293 * @node: Node to modify 294 * @filp: Open file to add 295 * 296 * Add @filp to the list of allowed open-files for this node. If @filp is 297 * already on this list, the ref-count is incremented. 298 * 299 * The list of allowed-users is preserved across drm_vma_offset_add() and 300 * drm_vma_offset_remove() calls. You may even call it if the node is currently 301 * not added to any offset-manager. 302 * 303 * You must remove all open-files the same number of times as you added them 304 * before destroying the node. Otherwise, you will leak memory. 305 * 306 * This is locked against concurrent access internally. 307 * 308 * RETURNS: 309 * 0 on success, negative error code on internal failure (out-of-mem) 310 */ 311int drm_vma_node_allow(struct drm_vma_offset_node *node, struct file *filp) 312{ 313 struct rb_node **iter; 314 struct rb_node *parent = NULL; 315 struct drm_vma_offset_file *new, *entry; 316 int ret = 0; 317 318 /* Preallocate entry to avoid atomic allocations below. It is quite 319 * unlikely that an open-file is added twice to a single node so we 320 * don't optimize for this case. OOM is checked below only if the entry 321 * is actually used. */ 322 new = kmalloc(sizeof(*entry), GFP_KERNEL); 323 324 write_lock(&node->vm_lock); 325 326 iter = &node->vm_files.rb_node; 327 328 while (likely(*iter)) { 329 parent = *iter; 330 entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb); 331 332 if (filp == entry->vm_filp) { 333 entry->vm_count++; 334 goto unlock; 335 } else if (filp > entry->vm_filp) { 336 iter = &(*iter)->rb_right; 337 } else { 338 iter = &(*iter)->rb_left; 339 } 340 } 341 342 if (!new) { 343 ret = -ENOMEM; 344 goto unlock; 345 } 346 347 new->vm_filp = filp; 348 new->vm_count = 1; 349 rb_link_node(&new->vm_rb, parent, iter); 350 rb_insert_color(&new->vm_rb, &node->vm_files); 351 new = NULL; 352 353unlock: 354 write_unlock(&node->vm_lock); 355 kfree(new); 356 return ret; 357} 358EXPORT_SYMBOL(drm_vma_node_allow); 359 360/** 361 * drm_vma_node_revoke - Remove open-file from list of allowed users 362 * @node: Node to modify 363 * @filp: Open file to remove 364 * 365 * Decrement the ref-count of @filp in the list of allowed open-files on @node. 366 * If the ref-count drops to zero, remove @filp from the list. You must call 367 * this once for every drm_vma_node_allow() on @filp. 368 * 369 * This is locked against concurrent access internally. 370 * 371 * If @filp is not on the list, nothing is done. 372 */ 373void drm_vma_node_revoke(struct drm_vma_offset_node *node, struct file *filp) 374{ 375 struct drm_vma_offset_file *entry; 376 struct rb_node *iter; 377 378 write_lock(&node->vm_lock); 379 380 iter = node->vm_files.rb_node; 381 while (likely(iter)) { 382 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb); 383 if (filp == entry->vm_filp) { 384 if (!--entry->vm_count) { 385 rb_erase(&entry->vm_rb, &node->vm_files); 386 kfree(entry); 387 } 388 break; 389 } else if (filp > entry->vm_filp) { 390 iter = iter->rb_right; 391 } else { 392 iter = iter->rb_left; 393 } 394 } 395 396 write_unlock(&node->vm_lock); 397} 398EXPORT_SYMBOL(drm_vma_node_revoke); 399 400/** 401 * drm_vma_node_is_allowed - Check whether an open-file is granted access 402 * @node: Node to check 403 * @filp: Open-file to check for 404 * 405 * Search the list in @node whether @filp is currently on the list of allowed 406 * open-files (see drm_vma_node_allow()). 407 * 408 * This is locked against concurrent access internally. 409 * 410 * RETURNS: 411 * true iff @filp is on the list 412 */ 413bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node, 414 struct file *filp) 415{ 416 struct drm_vma_offset_file *entry; 417 struct rb_node *iter; 418 419 read_lock(&node->vm_lock); 420 421 iter = node->vm_files.rb_node; 422 while (likely(iter)) { 423 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb); 424 if (filp == entry->vm_filp) 425 break; 426 else if (filp > entry->vm_filp) 427 iter = iter->rb_right; 428 else 429 iter = iter->rb_left; 430 } 431 432 read_unlock(&node->vm_lock); 433 434 return iter; 435} 436EXPORT_SYMBOL(drm_vma_node_is_allowed); 437