OSCL-LXR linux-6.0.1/​drivers/​gpu/​drm/​drm_vma_manager.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0 OR MIT
 /*
  * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
  * Copyright (c) 2012 David Airlie <airlied@linux.ie>
  * Copyright (c) 2013 David Herrmann <dh.herrmann@gmail.com>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  */
 
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/rbtree.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
 
 #include <drm/drm_mm.h>
 #include <drm/drm_vma_manager.h>
 
 /**
  * DOC: vma offset manager
  *
  * The vma-manager is responsible to map arbitrary driver-dependent memory
  * regions into the linear user address-space. It provides offsets to the
  * caller which can then be used on the address_space of the drm-device. It
  * takes care to not overlap regions, size them appropriately and to not
  * confuse mm-core by inconsistent fake vm_pgoff fields.
  * Drivers shouldn't use this for object placement in VMEM. This manager should
  * only be used to manage mappings into linear user-space VMs.
  *
  * We use drm_mm as backend to manage object allocations. But it is highly
  * optimized for alloc/free calls, not lookups. Hence, we use an rb-tree to
  * speed up offset lookups.
  *
  * You must not use multiple offset managers on a single address_space.
  * Otherwise, mm-core will be unable to tear down memory mappings as the VM will
  * no longer be linear.
  *
  * This offset manager works on page-based addresses. That is, every argument
  * and return code (with the exception of drm_vma_node_offset_addr()) is given
  * in number of pages, not number of bytes. That means, object sizes and offsets
  * must always be page-aligned (as usual).
  * If you want to get a valid byte-based user-space address for a given offset,
  * please see drm_vma_node_offset_addr().
  *
  * Additionally to offset management, the vma offset manager also handles access
  * management. For every open-file context that is allowed to access a given
  * node, you must call drm_vma_node_allow(). Otherwise, an mmap() call on this
  * open-file with the offset of the node will fail with -EACCES. To revoke
  * access again, use drm_vma_node_revoke(). However, the caller is responsible
  * for destroying already existing mappings, if required.
  */
 
 /**
  * drm_vma_offset_manager_init - Initialize new offset-manager
  * @mgr: Manager object
  * @page_offset: Offset of available memory area (page-based)
  * @size: Size of available address space range (page-based)
  *
  * Initialize a new offset-manager. The offset and area size available for the
  * manager are given as @page_offset and @size. Both are interpreted as
  * page-numbers, not bytes.
  *
  * Adding/removing nodes from the manager is locked internally and protected
  * against concurrent access. However, node allocation and destruction is left
  * for the caller. While calling into the vma-manager, a given node must
  * always be guaranteed to be referenced.
  */
 void drm_vma_offset_manager_init(struct drm_vma_offset_manager *mgr,
                  unsigned long page_offset, unsigned long size)
 {
     rwlock_init(&mgr->vm_lock);
     drm_mm_init(&mgr->vm_addr_space_mm, page_offset, size);
 }
 EXPORT_SYMBOL(drm_vma_offset_manager_init);
 
 /**
  * drm_vma_offset_manager_destroy() - Destroy offset manager
  * @mgr: Manager object
  *
  * Destroy an object manager which was previously created via
  * drm_vma_offset_manager_init(). The caller must remove all allocated nodes
  * before destroying the manager. Otherwise, drm_mm will refuse to free the
  * requested resources.
  *
  * The manager must not be accessed after this function is called.
  */
 void drm_vma_offset_manager_destroy(struct drm_vma_offset_manager *mgr)
 {
     drm_mm_takedown(&mgr->vm_addr_space_mm);
 }
 EXPORT_SYMBOL(drm_vma_offset_manager_destroy);
 
 /**
  * drm_vma_offset_lookup_locked() - Find node in offset space
  * @mgr: Manager object
  * @start: Start address for object (page-based)
  * @pages: Size of object (page-based)
  *
  * Find a node given a start address and object size. This returns the _best_
  * match for the given node. That is, @start may point somewhere into a valid
  * region and the given node will be returned, as long as the node spans the
  * whole requested area (given the size in number of pages as @pages).
  *
  * Note that before lookup the vma offset manager lookup lock must be acquired
  * with drm_vma_offset_lock_lookup(). See there for an example. This can then be
  * used to implement weakly referenced lookups using kref_get_unless_zero().
  *
  * Example:
  *
  * ::
  *
  *     drm_vma_offset_lock_lookup(mgr);
  *     node = drm_vma_offset_lookup_locked(mgr);
  *     if (node)
  *         kref_get_unless_zero(container_of(node, sth, entr));
  *     drm_vma_offset_unlock_lookup(mgr);
  *
  * RETURNS:
  * Returns NULL if no suitable node can be found. Otherwise, the best match
  * is returned. It's the caller's responsibility to make sure the node doesn't
  * get destroyed before the caller can access it.
  */
 struct drm_vma_offset_node *drm_vma_offset_lookup_locked(struct drm_vma_offset_manager *mgr,
                              unsigned long start,
                              unsigned long pages)
 {
     struct drm_mm_node *node, *best;
     struct rb_node *iter;
     unsigned long offset;
 
     iter = mgr->vm_addr_space_mm.interval_tree.rb_root.rb_node;
     best = NULL;
 
     while (likely(iter)) {
         node = rb_entry(iter, struct drm_mm_node, rb);
         offset = node->start;
         if (start >= offset) {
             iter = iter->rb_right;
             best = node;
             if (start == offset)
                 break;
         } else {
             iter = iter->rb_left;
         }
     }
 
     /* verify that the node spans the requested area */
     if (best) {
         offset = best->start + best->size;
         if (offset < start + pages)
             best = NULL;
     }
 
     if (!best)
         return NULL;
 
     return container_of(best, struct drm_vma_offset_node, vm_node);
 }
 EXPORT_SYMBOL(drm_vma_offset_lookup_locked);
 
 /**
  * drm_vma_offset_add() - Add offset node to manager
  * @mgr: Manager object
  * @node: Node to be added
  * @pages: Allocation size visible to user-space (in number of pages)
  *
  * Add a node to the offset-manager. If the node was already added, this does
  * nothing and return 0. @pages is the size of the object given in number of
  * pages.
  * After this call succeeds, you can access the offset of the node until it
  * is removed again.
  *
  * If this call fails, it is safe to retry the operation or call
  * drm_vma_offset_remove(), anyway. However, no cleanup is required in that
  * case.
  *
  * @pages is not required to be the same size as the underlying memory object
  * that you want to map. It only limits the size that user-space can map into
  * their address space.
  *
  * RETURNS:
  * 0 on success, negative error code on failure.
  */
 int drm_vma_offset_add(struct drm_vma_offset_manager *mgr,
                struct drm_vma_offset_node *node, unsigned long pages)
 {
     int ret = 0;
 
     write_lock(&mgr->vm_lock);
 
     if (!drm_mm_node_allocated(&node->vm_node))
         ret = drm_mm_insert_node(&mgr->vm_addr_space_mm,
                      &node->vm_node, pages);
 
     write_unlock(&mgr->vm_lock);
 
     return ret;
 }
 EXPORT_SYMBOL(drm_vma_offset_add);
 
 /**
  * drm_vma_offset_remove() - Remove offset node from manager
  * @mgr: Manager object
  * @node: Node to be removed
  *
  * Remove a node from the offset manager. If the node wasn't added before, this
  * does nothing. After this call returns, the offset and size will be 0 until a
  * new offset is allocated via drm_vma_offset_add() again. Helper functions like
  * drm_vma_node_start() and drm_vma_node_offset_addr() will return 0 if no
  * offset is allocated.
  */
 void drm_vma_offset_remove(struct drm_vma_offset_manager *mgr,
                struct drm_vma_offset_node *node)
 {
     write_lock(&mgr->vm_lock);
 
     if (drm_mm_node_allocated(&node->vm_node)) {
         drm_mm_remove_node(&node->vm_node);
         memset(&node->vm_node, 0, sizeof(node->vm_node));
     }
 
     write_unlock(&mgr->vm_lock);
 }
 EXPORT_SYMBOL(drm_vma_offset_remove);
 
 /**
  * drm_vma_node_allow - Add open-file to list of allowed users
  * @node: Node to modify
  * @tag: Tag of file to remove
  *
  * Add @tag to the list of allowed open-files for this node. If @tag is
  * already on this list, the ref-count is incremented.
  *
  * The list of allowed-users is preserved across drm_vma_offset_add() and
  * drm_vma_offset_remove() calls. You may even call it if the node is currently
  * not added to any offset-manager.
  *
  * You must remove all open-files the same number of times as you added them
  * before destroying the node. Otherwise, you will leak memory.
  *
  * This is locked against concurrent access internally.
  *
  * RETURNS:
  * 0 on success, negative error code on internal failure (out-of-mem)
  */
 int drm_vma_node_allow(struct drm_vma_offset_node *node, struct drm_file *tag)
 {
     struct rb_node **iter;
     struct rb_node *parent = NULL;
     struct drm_vma_offset_file *new, *entry;
     int ret = 0;
 
     /* Preallocate entry to avoid atomic allocations below. It is quite
      * unlikely that an open-file is added twice to a single node so we
      * don't optimize for this case. OOM is checked below only if the entry
      * is actually used. */
     new = kmalloc(sizeof(*entry), GFP_KERNEL);
 
     write_lock(&node->vm_lock);
 
     iter = &node->vm_files.rb_node;
 
     while (likely(*iter)) {
         parent = *iter;
         entry = rb_entry(*iter, struct drm_vma_offset_file, vm_rb);
 
         if (tag == entry->vm_tag) {
             entry->vm_count++;
             goto unlock;
         } else if (tag > entry->vm_tag) {
             iter = &(*iter)->rb_right;
         } else {
             iter = &(*iter)->rb_left;
         }
     }
 
     if (!new) {
         ret = -ENOMEM;
         goto unlock;
     }
 
     new->vm_tag = tag;
     new->vm_count = 1;
     rb_link_node(&new->vm_rb, parent, iter);
     rb_insert_color(&new->vm_rb, &node->vm_files);
     new = NULL;
 
 unlock:
     write_unlock(&node->vm_lock);
     kfree(new);
     return ret;
 }
 EXPORT_SYMBOL(drm_vma_node_allow);
 
 /**
  * drm_vma_node_revoke - Remove open-file from list of allowed users
  * @node: Node to modify
  * @tag: Tag of file to remove
  *
  * Decrement the ref-count of @tag in the list of allowed open-files on @node.
  * If the ref-count drops to zero, remove @tag from the list. You must call
  * this once for every drm_vma_node_allow() on @tag.
  *
  * This is locked against concurrent access internally.
  *
  * If @tag is not on the list, nothing is done.
  */
 void drm_vma_node_revoke(struct drm_vma_offset_node *node,
              struct drm_file *tag)
 {
     struct drm_vma_offset_file *entry;
     struct rb_node *iter;
 
     write_lock(&node->vm_lock);
 
     iter = node->vm_files.rb_node;
     while (likely(iter)) {
         entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
         if (tag == entry->vm_tag) {
             if (!--entry->vm_count) {
                 rb_erase(&entry->vm_rb, &node->vm_files);
                 kfree(entry);
             }
             break;
         } else if (tag > entry->vm_tag) {
             iter = iter->rb_right;
         } else {
             iter = iter->rb_left;
         }
     }
 
     write_unlock(&node->vm_lock);
 }
 EXPORT_SYMBOL(drm_vma_node_revoke);
 
 /**
  * drm_vma_node_is_allowed - Check whether an open-file is granted access
  * @node: Node to check
  * @tag: Tag of file to remove
  *
  * Search the list in @node whether @tag is currently on the list of allowed
  * open-files (see drm_vma_node_allow()).
  *
  * This is locked against concurrent access internally.
  *
  * RETURNS:
  * true if @filp is on the list
  */
 bool drm_vma_node_is_allowed(struct drm_vma_offset_node *node,
                  struct drm_file *tag)
 {
     struct drm_vma_offset_file *entry;
     struct rb_node *iter;
 
     read_lock(&node->vm_lock);
 
     iter = node->vm_files.rb_node;
     while (likely(iter)) {
         entry = rb_entry(iter, struct drm_vma_offset_file, vm_rb);
         if (tag == entry->vm_tag)
             break;
         else if (tag > entry->vm_tag)
             iter = iter->rb_right;
         else
             iter = iter->rb_left;
     }
 
     read_unlock(&node->vm_lock);
 
     return iter;
 }
 EXPORT_SYMBOL(drm_vma_node_is_allowed);

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