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 */ 85 void 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 } 92 EXPORT_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 */ 105 void 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 } 112 EXPORT_SYMBOL(drm_vma_offset_manager_destroy); 113 114 /** 115 * drm_vma_offset_lookup_locked() - 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 * Note that before lookup the vma offset manager lookup lock must be acquired 126 * with drm_vma_offset_lock_lookup(). See there for an example. This can then be 127 * used to implement weakly referenced lookups using kref_get_unless_zero(). 128 * 129 * Example: 130 * drm_vma_offset_lock_lookup(mgr); 131 * node = drm_vma_offset_lookup_locked(mgr); 132 * if (node) 133 * kref_get_unless_zero(container_of(node, sth, entr)); 134 * drm_vma_offset_unlock_lookup(mgr); 135 * 136 * RETURNS: 137 * Returns NULL if no suitable node can be found. Otherwise, the best match 138 * is returned. It's the caller's responsibility to make sure the node doesn't 139 * get destroyed before the caller can access it. 140 */ 141 struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr, 142 unsigned long start, 143 unsigned long pages) 144 { 145 struct drm_vma_offset_node *node, *best; 146 struct rb_node *iter; 147 unsigned long offset; 148 149 iter = mgr->vm_addr_space_rb.rb_node; 150 best = NULL; 151 152 while (likely(iter)) { 153 node = rb_entry(iter, struct drm_vma_offset_node, vm_rb); 154 offset = node->vm_node.start; 155 if (start >= offset) { 156 iter = iter->rb_right; 157 best = node; 158 if (start == offset) 159 break; 160 } else { 161 iter = iter->rb_left; 162 } 163 } 164 165 /* verify that the node spans the requested area */ 166 if (best) { 167 offset = best->vm_node.start + best->vm_node.size; 168 if (offset < start + pages) 169 best = NULL; 170 } 171 172 return best; 173 } 174 EXPORT_SYMBOL(drm_vma_offset_lookup_locked); 175 176 /* internal helper to link @node into the rb-tree */ 177 static void _drm_vma_offset_add_rb(struct drm_vma_offset_manager *mgr, 178 struct drm_vma_offset_node *node) 179 { 180 struct rb_node **iter = &mgr->vm_addr_space_rb.rb_node; 181 struct rb_node *parent = NULL; 182 struct drm_vma_offset_node *iter_node; 183 184 while (likely(*iter)) { 185 parent = *iter; 186 iter_node = rb_entry(*iter, struct drm_vma_offset_node, vm_rb); 187 188 if (node->vm_node.start < iter_node->vm_node.start) 189 iter = &(*iter)->rb_left; 190 else if (node->vm_node.start > iter_node->vm_node.start) 191 iter = &(*iter)->rb_right; 192 else 193 BUG(); 194 } 195 196 rb_link_node(&node->vm_rb, parent, iter); 197 rb_insert_color(&node->vm_rb, &mgr->vm_addr_space_rb); 198 } 199 200 /** 201 * drm_vma_offset_add() - Add offset node to manager 202 * @mgr: Manager object 203 * @node: Node to be added 204 * @pages: Allocation size visible to user-space (in number of pages) 205 * 206 * Add a node to the offset-manager. If the node was already added, this does 207 * nothing and return 0. @pages is the size of the object given in number of 208 * pages. 209 * After this call succeeds, you can access the offset of the node until it 210 * is removed again. 211 * 212 * If this call fails, it is safe to retry the operation or call 213 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that 214 * case. 215 * 216 * @pages is not required to be the same size as the underlying memory object 217 * that you want to map. It only limits the size that user-space can map into 218 * their address space. 219 * 220 * RETURNS: 221 * 0 on success, negative error code on failure. 222 */ 223 int drm_vma_offset_add(struct drm_vma_offset_manager *mgr, 224 struct drm_vma_offset_node *node, unsigned long pages) 225 { 226 int ret; 227 228 write_lock(&mgr->vm_lock); 229 230 if (drm_mm_node_allocated(&node->vm_node)) { 231 ret = 0; 232 goto out_unlock; 233 } 234 235 ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node, 236 pages, 0, DRM_MM_SEARCH_DEFAULT); 237 if (ret) 238 goto out_unlock; 239 240 _drm_vma_offset_add_rb(mgr, node); 241 242 out_unlock: 243 write_unlock(&mgr->vm_lock); 244 return ret; 245 } 246 EXPORT_SYMBOL(drm_vma_offset_add); 247 248 /** 249 * drm_vma_offset_remove() - Remove offset node from manager 250 * @mgr: Manager object 251 * @node: Node to be removed 252 * 253 * Remove a node from the offset manager. If the node wasn't added before, this 254 * does nothing. After this call returns, the offset and size will be 0 until a 255 * new offset is allocated via drm_vma_offset_add() again. Helper functions like 256 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no 257 * offset is allocated. 258 */ 259 void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr, 260 struct drm_vma_offset_node *node) 261 { 262 write_lock(&mgr->vm_lock); 263 264 if (drm_mm_node_allocated(&node->vm_node)) { 265 rb_erase(&node->vm_rb, &mgr->vm_addr_space_rb); 266 drm_mm_remove_node(&node->vm_node); 267 memset(&node->vm_node, 0, sizeof(node->vm_node)); 268 } 269 270 write_unlock(&mgr->vm_lock); 271 } 272 EXPORT_SYMBOL(drm_vma_offset_remove); 273 274 /** 275 * drm_vma_node_allow - Add open-file to list of allowed users 276 * @node: Node to modify 277 * @filp: Open file to add 278 * 279 * Add @filp to the list of allowed open-files for this node. If @filp is 280 * already on this list, the ref-count is incremented. 281 * 282 * The list of allowed-users is preserved across drm_vma_offset_add() and 283 * drm_vma_offset_remove() calls. You may even call it if the node is currently 284 * not added to any offset-manager. 285 * 286 * You must remove all open-files the same number of times as you added them 287 * before destroying the node. Otherwise, you will leak memory. 288 * 289 * This is locked against concurrent access internally. 290 * 291 * RETURNS: 292 * 0 on success, negative error code on internal failure (out-of-mem) 293 */ 294 int drm_vma_node_allow(struct drm_vma_offset_node *node, struct file *filp) 295 { 296 struct rb_node **iter; 297 struct rb_node *parent = NULL; 298 struct drm_vma_offset_file *new, *entry; 299 int ret = 0; 300 301 /* Preallocate entry to avoid atomic allocations below. It is quite 302 * unlikely that an open-file is added twice to a single node so we 303 * don't optimize for this case. OOM is checked below only if the entry 304 * is actually used. */ 305 new = kmalloc(sizeof(*entry), GFP_KERNEL); 306 307 write_lock(&node->vm_lock); 308 309 iter = &node->vm_files.rb_node; 310 311 while (likely(*iter)) { 312 parent = *iter; 313 entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb); 314 315 if (filp == entry->vm_filp) { 316 entry->vm_count++; 317 goto unlock; 318 } else if (filp > entry->vm_filp) { 319 iter = &(*iter)->rb_right; 320 } else { 321 iter = &(*iter)->rb_left; 322 } 323 } 324 325 if (!new) { 326 ret = -ENOMEM; 327 goto unlock; 328 } 329 330 new->vm_filp = filp; 331 new->vm_count = 1; 332 rb_link_node(&new->vm_rb, parent, iter); 333 rb_insert_color(&new->vm_rb, &node->vm_files); 334 new = NULL; 335 336 unlock: 337 write_unlock(&node->vm_lock); 338 kfree(new); 339 return ret; 340 } 341 EXPORT_SYMBOL(drm_vma_node_allow); 342 343 /** 344 * drm_vma_node_revoke - Remove open-file from list of allowed users 345 * @node: Node to modify 346 * @filp: Open file to remove 347 * 348 * Decrement the ref-count of @filp in the list of allowed open-files on @node. 349 * If the ref-count drops to zero, remove @filp from the list. You must call 350 * this once for every drm_vma_node_allow() on @filp. 351 * 352 * This is locked against concurrent access internally. 353 * 354 * If @filp is not on the list, nothing is done. 355 */ 356 void drm_vma_node_revoke(struct drm_vma_offset_node *node, struct file *filp) 357 { 358 struct drm_vma_offset_file *entry; 359 struct rb_node *iter; 360 361 write_lock(&node->vm_lock); 362 363 iter = node->vm_files.rb_node; 364 while (likely(iter)) { 365 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb); 366 if (filp == entry->vm_filp) { 367 if (!--entry->vm_count) { 368 rb_erase(&entry->vm_rb, &node->vm_files); 369 kfree(entry); 370 } 371 break; 372 } else if (filp > entry->vm_filp) { 373 iter = iter->rb_right; 374 } else { 375 iter = iter->rb_left; 376 } 377 } 378 379 write_unlock(&node->vm_lock); 380 } 381 EXPORT_SYMBOL(drm_vma_node_revoke); 382 383 /** 384 * drm_vma_node_is_allowed - Check whether an open-file is granted access 385 * @node: Node to check 386 * @filp: Open-file to check for 387 * 388 * Search the list in @node whether @filp is currently on the list of allowed 389 * open-files (see drm_vma_node_allow()). 390 * 391 * This is locked against concurrent access internally. 392 * 393 * RETURNS: 394 * true iff @filp is on the list 395 */ 396 bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node, 397 struct file *filp) 398 { 399 struct drm_vma_offset_file *entry; 400 struct rb_node *iter; 401 402 read_lock(&node->vm_lock); 403 404 iter = node->vm_files.rb_node; 405 while (likely(iter)) { 406 entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb); 407 if (filp == entry->vm_filp) 408 break; 409 else if (filp > entry->vm_filp) 410 iter = iter->rb_right; 411 else 412 iter = iter->rb_left; 413 } 414 415 read_unlock(&node->vm_lock); 416 417 return iter; 418 } 419 EXPORT_SYMBOL(drm_vma_node_is_allowed); 420