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