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/**************************************************************************
*
* Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.
* Copyright 2016 Intel Corporation
* All Rights Reserved.
*
* 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, sub license, 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 (including the
* next paragraph) 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 NON-INFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS 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.
*
*
**************************************************************************/
/*
* Generic simple memory manager implementation. Intended to be used as a base
* class implementation for more advanced memory managers.
*
* Note that the algorithm used is quite simple and there might be substantial
* performance gains if a smarter free list is implemented. Currently it is
* just an unordered stack of free regions. This could easily be improved if
* an RB-tree is used instead. At least if we expect heavy fragmentation.
*
* Aligned allocations can also see improvement.
*
* Authors:
* Thomas Hellström <thomas-at-tungstengraphics-dot-com>
*/
#include <drm/drmP.h>
#include <drm/drm_mm.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/export.h>
#include <linux/interval_tree_generic.h>
/**
* DOC: Overview
*
* drm_mm provides a simple range allocator. The drivers are free to use the
* resource allocator from the linux core if it suits them, the upside of drm_mm
* is that it's in the DRM core. Which means that it's easier to extend for
* some of the crazier special purpose needs of gpus.
*
* The main data struct is &drm_mm, allocations are tracked in &drm_mm_node.
* Drivers are free to embed either of them into their own suitable
* datastructures. drm_mm itself will not do any allocations of its own, so if
* drivers choose not to embed nodes they need to still allocate them
* themselves.
*
* The range allocator also supports reservation of preallocated blocks. This is
* useful for taking over initial mode setting configurations from the firmware,
* where an object needs to be created which exactly matches the firmware's
* scanout target. As long as the range is still free it can be inserted anytime
* after the allocator is initialized, which helps with avoiding looped
* dependencies in the driver load sequence.
*
* drm_mm maintains a stack of most recently freed holes, which of all
* simplistic datastructures seems to be a fairly decent approach to clustering
* allocations and avoiding too much fragmentation. This means free space
* searches are O(num_holes). Given that all the fancy features drm_mm supports
* something better would be fairly complex and since gfx thrashing is a fairly
* steep cliff not a real concern. Removing a node again is O(1).
*
* drm_mm supports a few features: Alignment and range restrictions can be
* supplied. Further more every &drm_mm_node has a color value (which is just an
* opaque unsigned long) which in conjunction with a driver callback can be used
* to implement sophisticated placement restrictions. The i915 DRM driver uses
* this to implement guard pages between incompatible caching domains in the
* graphics TT.
*
* Two behaviors are supported for searching and allocating: bottom-up and
* top-down. The default is bottom-up. Top-down allocation can be used if the
* memory area has different restrictions, or just to reduce fragmentation.
*
* Finally iteration helpers to walk all nodes and all holes are provided as are
* some basic allocator dumpers for debugging.
*
* Note that this range allocator is not thread-safe, drivers need to protect
* modifications with their on locking. The idea behind this is that for a full
* memory manager additional data needs to be protected anyway, hence internal
* locking would be fully redundant.
*/
static struct drm_mm_node *drm_mm_search_free_in_range_generic(const struct drm_mm *mm,
u64 size,
u64 alignment,
unsigned long color,
u64 start,
u64 end,
enum drm_mm_search_flags flags);
#ifdef CONFIG_DRM_DEBUG_MM
#include <linux/stackdepot.h>
#define STACKDEPTH 32
#define BUFSZ 4096
static noinline void save_stack(struct drm_mm_node *node)
{
unsigned long entries[STACKDEPTH];
struct stack_trace trace = {
.entries = entries,
.max_entries = STACKDEPTH,
.skip = 1
};
save_stack_trace(&trace);
if (trace.nr_entries != 0 &&
trace.entries[trace.nr_entries-1] == ULONG_MAX)
trace.nr_entries--;
/* May be called under spinlock, so avoid sleeping */
node->stack = depot_save_stack(&trace, GFP_NOWAIT);
}
static void show_leaks(struct drm_mm *mm)
{
struct drm_mm_node *node;
unsigned long entries[STACKDEPTH];
char *buf;
buf = kmalloc(BUFSZ, GFP_KERNEL);
if (!buf)
return;
list_for_each_entry(node, drm_mm_nodes(mm), node_list) {
struct stack_trace trace = {
.entries = entries,
.max_entries = STACKDEPTH
};
if (!node->stack) {
DRM_ERROR("node [%08llx + %08llx]: unknown owner\n",
node->start, node->size);
continue;
}
depot_fetch_stack(node->stack, &trace);
snprint_stack_trace(buf, BUFSZ, &trace, 0);
DRM_ERROR("node [%08llx + %08llx]: inserted at\n%s",
node->start, node->size, buf);
}
kfree(buf);
}
#undef STACKDEPTH
#undef BUFSZ
#else
static void save_stack(struct drm_mm_node *node) { }
static void show_leaks(struct drm_mm *mm) { }
#endif
#define START(node) ((node)->start)
#define LAST(node) ((node)->start + (node)->size - 1)
INTERVAL_TREE_DEFINE(struct drm_mm_node, rb,
u64, __subtree_last,
START, LAST, static inline, drm_mm_interval_tree)
struct drm_mm_node *
__drm_mm_interval_first(const struct drm_mm *mm, u64 start, u64 last)
{
return drm_mm_interval_tree_iter_first((struct rb_root *)&mm->interval_tree,
start, last);
}
EXPORT_SYMBOL(__drm_mm_interval_first);
static void drm_mm_interval_tree_add_node(struct drm_mm_node *hole_node,
struct drm_mm_node *node)
{
struct drm_mm *mm = hole_node->mm;
struct rb_node **link, *rb;
struct drm_mm_node *parent;
node->__subtree_last = LAST(node);
if (hole_node->allocated) {
rb = &hole_node->rb;
while (rb) {
parent = rb_entry(rb, struct drm_mm_node, rb);
if (parent->__subtree_last >= node->__subtree_last)
break;
parent->__subtree_last = node->__subtree_last;
rb = rb_parent(rb);
}
rb = &hole_node->rb;
link = &hole_node->rb.rb_right;
} else {
rb = NULL;
link = &mm->interval_tree.rb_node;
}
while (*link) {
rb = *link;
parent = rb_entry(rb, struct drm_mm_node, rb);
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