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/mm.h> 29 #include <linux/module.h> 30 #include <linux/rbtree.h> 31 #include <linux/slab.h> 32 #include <linux/spinlock.h> 33 #include <linux/types.h> 34 35 /** 36 * DOC: vma offset manager 37 * 38 * The vma-manager is responsible to map arbitrary driver-dependent memory 39 * regions into the linear user address-space. It provides offsets to the 40 * caller which can then be used on the address_space of the drm-device. It 41 * takes care to not overlap regions, size them appropriately and to not 42 * confuse mm-core by inconsistent fake vm_pgoff fields. 43 * Drivers shouldn't use this for object placement in VMEM. This manager should 44 * only be used to manage mappings into linear user-space VMs. 45 * 46 * We use drm_mm as backend to manage object allocations. But it is highly 47 * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to 48 * speed up offset lookups. 49 * 50 * You must not use multiple offset managers on a single address_space. 51 * Otherwise, mm-core will be unable to tear down memory mappings as the VM will 52 * no longer be linear. 53 * 54 * This offset manager works on page-based addresses. That is, every argument 55 * and return code (with the exception of drm_vma_node_offset_addr()) is given 56 * in number of pages, not number of bytes. That means, object sizes and offsets 57 * must always be page-aligned (as usual). 58 * If you want to get a valid byte-based user-space address for a given offset, 59 * please see drm_vma_node_offset_addr(). 60 * 61 * Additionally to offset management, the vma offset manager also handles access 62 * management. For every open-file context that is allowed to access a given 63 * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this 64 * open-file with the offset of the node will fail with -EACCES. To revoke 65 * access again, use drm_vma_node_revoke(). However, the caller is responsible 66 * for destroying already existing mappings, if required. 67 */ 68 69 /** 70 * drm_vma_offset_manager_init - Initialize new offset-manager 71 * @mgr: Manager object 72 * @page_offset: Offset of available memory area (page-based) 73 * @size: Size of available address space range (page-based) 74 * 75 * Initialize a new offset-manager. The offset and area size available for the 76 * manager are given as @page_offset and @size. Both are interpreted as 77 * page-numbers, not bytes. 78 * 79 * Adding/removing nodes from the manager is locked internally and protected 80 * against concurrent access. However, node allocation and destruction is left 81 * for the caller. While calling into the vma-manager, a given node must 82 * always be guaranteed to be referenced. 83 */ 84 void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr, 85 unsigned long page_offset, unsigned long size) 86 { 87 lockinit(&mgr->vm_lock, "drmvml", 0, LK_CANRECURSE); 88 mgr->vm_addr_space_rb = LINUX_RB_ROOT; 89 drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size); 90 } 91 EXPORT_SYMBOL(drm_vma_offset_manager_init); 92 93 /** 94 * drm_vma_offset_manager_destroy() - Destroy offset manager 95 * @mgr: Manager object 96 * 97 * Destroy an object manager which was previously created via 98 * drm_vma_offset_manager_init(). The caller must remove all allocated nodes 99 * before destroying the manager. Otherwise, drm_mm will refuse to free the 100 * requested resources. 101 * 102 * The manager must not be accessed after this function is called. 103 */ 104 void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr) 105 { 106 /* take the lock to protect against buggy drivers */ 107 lockmgr(&mgr->vm_lock, LK_EXCLUSIVE); 108 drm_mm_takedown(&mgr->vm_addr_space_mm); 109 lockmgr(&mgr->vm_lock, LK_RELEASE); 110 } 111 EXPORT_SYMBOL(drm_vma_offset_manager_destroy); 112 113 /** 114 * drm_vma_offset_lookup_locked() - Find node in offset space 115 * @mgr: Manager object 116 * @start: Start address for object (page-based) 117 * @pages: Size of object (page-based) 118 * 119 * Find a node given a start address and object size. This returns the _best_ 120 * match for the given node. That is, @start may point somewhere into a valid 121 * region and the given node will be returned, as long as the node spans the 122 * whole requested area (given the size in number of pages as @pages). 123 * 124 * Note that before lookup the vma offset manager lookup lock must be acquired 125 * with drm_vma_offset_lock_lookup(). See there for an example. This can then be 126 * used to implement weakly referenced lookups using kref_get_unless_zero(). 127 * 128 * Example: 129 * 130 * :: 131 * 132 * drm_vma_offset_lock_lookup(mgr); 133 * node = drm_vma_offset_lookup_locked(mgr); 134 * if (node) 135 * kref_get_unless_zero(container_of(node, sth, entr)); 136 * drm_vma_offset_unlock_lookup(mgr); 137 * 138 * RETURNS: 139 * Returns NULL if no suitable node can be found. Otherwise, the best match 140 * is returned. It's the caller's responsibility to make sure the node doesn't 141 * get destroyed before the caller can access it. 142 */ 143 struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr, 144 unsigned long start, 145 unsigned long pages) 146 { 147 struct drm_vma_offset_node *node, *best; 148 struct rb_node *iter; 149 unsigned long offset; 150 151 iter = mgr->vm_addr_space_rb.rb_node; 152 best = NULL; 153 154 while (likely(iter)) { 155 node = rb_entry(iter, struct drm_vma_offset_node, vm_rb); 156 offset = node->vm_node.start; 157 if (start >= offset) { 158 iter = iter->rb_right; 159 best = node; 160 if (start == offset) 161 break; 162 } else { 163 iter = iter->rb_left; 164 } 165 } 166 167 /* verify that the node spans the requested area */ 168 if (best) { 169 offset = best->vm_node.start + best->vm_node.size; 170 if (offset < start + pages) 171 best = NULL; 172 } 173 174 return best; 175 } 176 EXPORT_SYMBOL(drm_vma_offset_lookup_locked); 177 178 /* internal helper to link @node into the rb-tree */ 179 static void _drm_vma_offset_add_rb(struct drm_vma_offset_manager *mgr, 180 struct drm_vma_offset_node *node) 181 { 182 struct rb_node **iter = &mgr->vm_addr_space_rb.rb_node; 183 struct rb_node *parent = NULL; 184 struct drm_vma_offset_node *iter_node; 185 186 while (likely(*iter)) { 187 parent = *iter; 188 iter_node = rb_entry(*iter, struct drm_vma_offset_node, vm_rb); 189 190 if (node->vm_node.start < iter_node->vm_node.start) 191 iter = &(*iter)->rb_left; 192 else if (node->vm_node.start > iter_node->vm_node.start) 193 iter = &(*iter)->rb_right; 194 else 195 BUG(); 196 } 197 198 rb_link_node(&node->vm_rb, parent, iter); 199 rb_insert_color(&node->vm_rb, &mgr->vm_addr_space_rb); 200 } 201 202 /** 203 * drm_vma_offset_add() - Add offset node to manager 204 * @mgr: Manager object 205 * @node: Node to be added 206 * @pages: Allocation size visible to user-space (in number of pages) 207 * 208 * Add a node to the offset-manager. If the node was already added, this does 209 * nothing and return 0. @pages is the size of the object given in number of 210 * pages. 211 * After this call succeeds, you can access the offset of the node until it 212 * is removed again. 213 * 214 * If this call fails, it is safe to retry the operation or call 215 * drm_vma_offset_remove(), anyway. However, no cleanup is required in that 216 * case. 217 * 218 * @pages is not required to be the same size as the underlying memory object 219 * that you want to map. It only limits the size that user-space can map into 220 * their address space. 221 * 222 * RETURNS: 223 * 0 on success, negative error code on failure. 224 */ 225 int drm_vma_offset_add(struct drm_vma_offset_manager *mgr, 226 struct drm_vma_offset_node *node, unsigned long pages) 227 { 228 int ret; 229 230 lockmgr(&mgr->vm_lock, LK_EXCLUSIVE); 231 232 if (drm_mm_node_allocated(&node->vm_node)) { 233 ret = 0; 234 goto out_unlock; 235 } 236 237 ret = drm_mm_insert_node(&mgr->vm_addr_space_mm, &node->vm_node, pages); 238 if (ret) 239 goto out_unlock; 240 241 _drm_vma_offset_add_rb(mgr, node); 242 243 out_unlock: 244 lockmgr(&mgr->vm_lock, LK_RELEASE); 245 return ret; 246 } 247 EXPORT_SYMBOL(drm_vma_offset_add); 248 249 /** 250 * drm_vma_offset_remove() - Remove offset node from manager 251 * @mgr: Manager object 252 * @node: Node to be removed 253 * 254 * Remove a node from the offset manager. If the node wasn't added before, this 255 * does nothing. After this call returns, the offset and size will be 0 until a 256 * new offset is allocated via drm_vma_offset_add() again. Helper functions like 257 * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no 258 * offset is allocated. 259 */ 260 void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr, 261 struct drm_vma_offset_node *node) 262 { 263 lockmgr(&mgr->vm_lock, LK_EXCLUSIVE); 264 265 if (drm_mm_node_allocated(&node->vm_node)) { 266 rb_erase(&node->vm_rb, &mgr->vm_addr_space_rb); 267 drm_mm_remove_node(&node->vm_node); 268 memset(&node->vm_node, 0, sizeof(node->vm_node)); 269 } 270 271 lockmgr(&mgr->vm_lock, LK_RELEASE); 272 } 273 EXPORT_SYMBOL(drm_vma_offset_remove); 274 275 /** 276 * drm_vma_node_allow - Add open-file to list of allowed users 277 * @node: Node to modify 278 * @tag: Tag of file to remove 279 * 280 * Add @tag to the list of allowed open-files for this node. If @tag is 281 * already on this list, the ref-count is incremented. 282 * 283 * The list of allowed-users is preserved across drm_vma_offset_add() and 284 * drm_vma_offset_remove() calls. You may even call it if the node is currently 285 * not added to any offset-manager. 286 * 287 * You must remove all open-files the same number of times as you added them 288 * before destroying the node. Otherwise, you will leak memory. 289 * 290 * This is locked against concurrent access internally. 291 * 292 * RETURNS: 293 * 0 on success, negative error code on internal failure (out-of-mem) 294 */ 295 int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag) 296 { 297 struct rb_node **iter; 298 struct rb_node *parent = NULL; 299 struct drm_vma_offset_file *new, *entry; 300 int ret = 0; 301 302 /* Preallocate entry to avoid atomic allocations below. It is quite 303 * unlikely that an open-file is added twice to a single node so we 304 * don't optimize for this case. OOM is checked below only if the entry 305 * is actually used. */ 306 new = kmalloc(sizeof(*entry), M_DRM, M_WAITOK); 307 308 lockmgr(&node->vm_lock, LK_EXCLUSIVE); 309 310 iter = &node->vm_files.rb_node; 311 312 while (likely(*iter)) { 313 parent = *iter; 314 entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb); 315 316 if (tag == entry->vm_tag) { 317 entry->vm_count++; 318 goto unlock; 319 } else if (tag > entry->vm_tag) { 320 iter = &(*iter)->rb_right; 321 } else { 322 iter = &(*iter)->rb_left; 323 } 324 } 325 326 if (!new) { 327 ret = -ENOMEM; 328 goto unlock; 329 } 330 331 new->vm_tag = tag; 332 new->vm_count = 1; 333 rb_link_node(&new->vm_rb, parent, iter); 334 rb_insert_color(&new->vm_rb, &node->vm_files); 335 new = NULL; 336 337 unlock: 338 lockmgr(&node->vm_lock, LK_RELEASE); 339 kfree(new); 340 return ret; 341 } 342 EXPORT_SYMBOL(drm_vma_node_allow); 343 344 /** 345 * drm_vma_node_revoke - Remove open-file from list of allowed users 346 * @node: Node to modify 347 * @tag: Tag of file to remove 348 * 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 call 351 * 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 */ 357 void 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 lockmgr(&node->vm_lock, LK_EXCLUSIVE); 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 lockmgr(&node->vm_lock, LK_RELEASE); 382 } 383 EXPORT_SYMBOL(drm_vma_node_revoke); 384 385 /** 386 * drm_vma_node_is_allowed - Check whether an open-file is granted access 387 * @node: Node to check 388 * @tag: Tag of file to remove 389 * 390 * Search the list in @node whether @tag is currently on the list of allowed 391 * open-files (see drm_vma_node_allow()). 392 * 393 * This is locked against concurrent access internally. 394 * 395 * RETURNS: 396 * true iff @filp is on the list 397 */ 398 bool 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 lockmgr(&node->vm_lock, LK_EXCLUSIVE); 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 else 414 iter = iter->rb_left; 415 } 416 417 lockmgr(&node->vm_lock, LK_RELEASE); 418 419 return iter; 420 } 421 EXPORT_SYMBOL(drm_vma_node_is_allowed); 422