diff options
Diffstat (limited to 'drivers/gpu/drm/drm_vma_manager.c')
| -rw-r--r-- | drivers/gpu/drm/drm_vma_manager.c | 389 |
1 files changed, 389 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_vma_manager.c b/drivers/gpu/drm/drm_vma_manager.c new file mode 100644 index 000000000..4565319fa --- /dev/null +++ b/drivers/gpu/drm/drm_vma_manager.c @@ -0,0 +1,389 @@ +// 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 iff @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); |