drivers/gpu/drm/drm_vma_manager.c

   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  */
  86 void 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 }
  93 EXPORT_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  */
 106 void 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 }
 113 EXPORT_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  */
 131 struct 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 }
 143 EXPORT_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  */
 158 struct 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 }
 191 EXPORT_SYMBOL(drm_vma_offset_lookup_locked);
 192
 193 /* internal helper to link @node into the rb-tree */
 194 static 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  */
 240 int 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
 259 out_unlock:
 260         write_unlock(&mgr->vm_lock);
 261         return ret;
 262 }
 263 EXPORT_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  */
 276 void 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 }
 289 EXPORT_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  */
 311 int 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
 353 unlock:
 354         write_unlock(&node->vm_lock);
 355         kfree(new);
 356         return ret;
 357 }
 358 EXPORT_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  */
 373 void 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 }
 398 EXPORT_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  */
 413 bool 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 }
 436 EXPORT_SYMBOL(drm_vma_node_is_allowed);