Changeset View
Changeset View
Standalone View
Standalone View
sys/dev/drm/core/drm_vma_manager.c
- This file was added.
// 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; | |||||
#ifdef __linux__ | |||||
struct rb_node *iter; | |||||
#endif | |||||
unsigned long offset; | |||||
#ifdef __linux__ | |||||
iter = mgr->vm_addr_space_mm.interval_tree.rb_root.rb_node; | |||||
#endif | |||||
best = NULL; | |||||
#ifdef __linux__ | |||||
while (likely(iter)) { | |||||
node = rb_entry(iter, struct drm_mm_node, rb); | |||||
#elif defined(__FreeBSD__) | |||||
drm_mm_for_each_node(node, &mgr->vm_addr_space_mm) { | |||||
#endif | |||||
offset = node->start; | |||||
if (start >= offset) { | |||||
#ifdef __linux__ | |||||
iter = iter->rb_right; | |||||
#endif | |||||
best = node; | |||||
if (start == offset) | |||||
break; | |||||
#ifdef __linux__ | |||||
} else { | |||||
iter = iter->rb_left; | |||||
#endif | |||||
} | |||||
} | |||||
/* 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); |