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.
  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() - 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  */
 130 struct 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 }
 142 EXPORT_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  */
 157 struct 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 }
 190 EXPORT_SYMBOL(drm_vma_offset_lookup_locked);
 191
 192 /* internal helper to link @node into the rb-tree */
 193 static 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  */
 239 int 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
 258 out_unlock:
 259         write_unlock(&mgr->vm_lock);
 260         return ret;
 261 }
 262 EXPORT_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  */
 275 void 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 }
 288 EXPORT_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  */
 310 int 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
 352 unlock:
 353         write_unlock(&node->vm_lock);
 354         kfree(new);
 355         return ret;
 356 }
 357 EXPORT_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  */
 372 void 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 }
 397 EXPORT_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  */
 412 bool 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 }
 435 EXPORT_SYMBOL(drm_vma_node_is_allowed);