Subversion Repositories Kolibri OS

Rev

Rev 4560 | Blame | Compare with Previous | Last modification | View Log | Download | RSS feed

  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.