summaryrefslogtreecommitdiffstats
path: root/drivers/gpu/drm/drm_mm.c
blob: 93d48a6f04abe26c2b7468c774487e8b0bc6e78a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
/**************************************************************************
 *
 * 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 <linux/export.h>
#include <linux/interval_tree_generic.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/stacktrace.h>

#include <drm/drm_mm.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 memory 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. Furthermore 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 own 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.
 */

#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];
	unsigned int n;

	n = stack_trace_save(entries, ARRAY_SIZE(entries), 1);

	/* May be called under spinlock, so avoid sleeping */
	node->stack = stack_depot_save(entries, n, GFP_NOWAIT);
}

static void show_leaks(struct drm_mm *mm)
{
	struct drm_mm_node *node;
	unsigned long *entries;
	unsigned int nr_entries;
	char *buf;

	buf = kmalloc(BUFSZ, GFP_KERNEL);
	if (!buf)
		return;

	list_for_each_entry(node, drm_mm_nodes(mm), node_list) {
		if (!node->stack) {
			DRM_ERROR("node [%08llx + %08llx]: unknown owner\n",
				  node->start, node->size);
			continue;
		}

		nr_entries = stack_depot_fetch(node->stack, &entries);
		stack_trace_snprint(buf, BUFSZ, entries, nr_entries, 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_cached *)&mm->interval_tree,
					       start, last) ?: (struct drm_mm_node *)&mm->head_node;
}
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;
	bool leftmost;

	node->__subtree_last = LAST(node);

	if (drm_mm_node_allocated(hole_node)) {
		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;
		leftmost = false;
	} else {
		rb = NULL;
		link = &mm->interval_tree.rb_root.rb_node;
		leftmost = true;
	}

	while (*link) {
		rb = *link;
		parent = rb_entry(rb, struct drm_mm_node, rb);
		if (parent->__subtree_last < node->__subtree_last)
			parent->__subtree_last = node->__subtree_last;
		if (node->start < parent->start) {
			link = &parent->rb.rb_left;
		} else {
			link = &parent->rb.rb_right;
			leftmost = false;
		}
	}

	rb_link_node(&node->rb, rb, link);
	rb_insert_augmented_cached(&node->rb, &mm->interval_tree, leftmost,
				   &drm_mm_interval_tree_augment);
}

#define HOLE_SIZE(NODE) ((NODE)->hole_size)
#define HOLE_ADDR(NODE) (__drm_mm_hole_node_start(NODE))

static u64 rb_to_hole_size(struct rb_node *rb)
{
	return rb_entry(rb, struct drm_mm_node, rb_hole_size)->hole_size;
}

static void insert_hole_size(struct rb_root_cached *root,
			     struct drm_mm_node *node)
{
	struct rb_node **link = &root->rb_root.rb_node, *rb = NULL;
	u64 x = node->hole_size;
	bool first = true;

	while (*link) {
		rb = *link;
		if (x > rb_to_hole_size(rb)) {
			link = &rb->rb_left;
		} else {
			link = &rb->rb_right;
			first = false;
		}
	}

	rb_link_node(&node->rb_hole_size, rb, link);
	rb_insert_color_cached(&node->rb_hole_size, root, first);
}

RB_DECLARE_CALLBACKS_MAX(static, augment_callbacks,
			 struct drm_mm_node, rb_hole_addr,
			 u64, subtree_max_hole, HOLE_SIZE)

static void insert_hole_addr(struct rb_root *root, struct drm_mm_node *node)
{
	struct rb_node **link = &root->rb_node, *rb_parent = NULL;
	u64 start = HOLE_ADDR(node), subtree_max_hole = node->subtree_max_hole;
	struct drm_mm_node *parent;

	while (*link) {
		rb_parent = *link;
		parent = rb_entry(rb_parent, struct drm_mm_node, rb_hole_addr);
		if (parent->subtree_max_hole < subtree_max_hole)
			parent->subtree_max_hole = subtree_max_hole;
		if (start < HOLE_ADDR(parent))
			link = &parent->rb_hole_addr.rb_left;
		else
			link = &parent->rb_hole_addr.rb_right;
	}

	rb_link_node(&node->rb_hole_addr, rb_parent, link);
	rb_insert_augmented(&node->rb_hole_addr, root, &augment_callbacks);
}

static void add_hole(struct drm_mm_node *node)
{
	struct drm_mm *mm = node->mm;

	node->hole_size =
		__drm_mm_hole_node_end(node) - __drm_mm_hole_node_start(node);
	node->subtree_max_hole = node->hole_size;
	DRM_MM_BUG_ON(!drm_mm_hole_follows(node));

	insert_hole_size(&mm->holes_size, node);
	insert_hole_addr(&mm->holes_addr, node);

	list_add(&node->hole_stack, &mm->hole_stack);
}

static void rm_hole(struct drm_mm_node *node)
{
	DRM_MM_BUG_ON(!drm_mm_hole_follows(node));

	list_del(&node->hole_stack);
	rb_erase_cached(&node->rb_hole_size, &node->mm->holes_size);
	rb_erase_augmented(&node->rb_hole_addr, &node->mm->holes_addr,
			   &augment_callbacks);
	node->hole_size = 0;
	node->subtree_max_hole = 0;

	DRM_MM_BUG_ON(drm_mm_hole_follows(node));
}

static inline struct drm_mm_node *rb_hole_size_to_node(struct rb_node *rb)
{
	return rb_entry_safe(rb, struct drm_mm_node, rb_hole_size);
}

static inline struct drm_mm_node *rb_hole_addr_to_node(struct rb_node *rb)
{
	return rb_entry_safe(rb, struct drm_mm_node, rb_hole_addr);
}

static struct drm_mm_node *best_hole(struct drm_mm *mm, u64 size)
{
	struct rb_node *rb = mm->holes_size.rb_root.rb_node;
	struct drm_mm_node *best = NULL;

	do {
		struct drm_mm_node *node =
			rb_entry(rb, struct drm_mm_node, rb_hole_size);

		if (size <= node->hole_size) {
			best = node;
			rb = rb->rb_right;
		} else {
			rb = rb->rb_left;
		}
	} while (rb);

	return best;
}

static bool usable_hole_addr(struct rb_node *rb, u64 size)
{
	return rb && rb_hole_addr_to_node(rb)->subtree_max_hole >= size;
}

static struct drm_mm_node *find_hole_addr(struct drm_mm *mm, u64 addr, u64 size)
{
	struct rb_node *rb = mm->holes_addr.rb_node;
	struct drm_mm_node *node = NULL;

	while (rb) {
		u64 hole_start;

		if (!usable_hole_addr(rb, size))
			break;

		node = rb_hole_addr_to_node(rb);
		hole_start = __drm_mm_hole_node_start(node);

		if (addr < hole_start)
			rb = node->rb_hole_addr.rb_left;
		else if (addr > hole_start + node->hole_size)
			rb = node->rb_hole_addr.rb_right;
		else
			break;
	}

	return node;
}

static struct drm_mm_node *
first_hole(struct drm_mm *mm,
	   u64 start, u64 end, u64 size,
	   enum drm_mm_insert_mode mode)
{
	switch (mode) {
	default:
	case DRM_MM_INSERT_BEST:
		return best_hole(mm, size);

	case DRM_MM_INSERT_LOW:
		return find_hole_addr(mm, start, size);

	case DRM_MM_INSERT_HIGH:
		return find_hole_addr(mm, end, size);

	case DRM_MM_INSERT_EVICT:
		return list_first_entry_or_null(&mm->hole_stack,
						struct drm_mm_node,
						hole_stack);
	}
}

/**
 * DECLARE_NEXT_HOLE_ADDR - macro to declare next hole functions
 * @name: name of function to declare
 * @first: first rb member to traverse (either rb_left or rb_right).
 * @last: last rb member to traverse (either rb_right or rb_left).
 *
 * This macro declares a function to return the next hole of the addr rb tree.
 * While traversing the tree we take the searched size into account and only
 * visit branches with potential big enough holes.
 */

#define DECLARE_NEXT_HOLE_ADDR(name, first, last)			\
static struct drm_mm_node *name(struct drm_mm_node *entry, u64 size)	\
{									\
	struct rb_node *parent, *node = &entry->rb_hole_addr;		\
									\
	if (!entry || RB_EMPTY_NODE(node))				\
		return NULL;						\
									\
	if (usable_hole_addr(node->first, size)) {			\
		node = node->first;					\
		while (usable_hole_addr(node->last, size))		\
			node = node->last;				\
		return rb_hole_addr_to_node(node);			\
	}								\
									\
	while ((parent = rb_parent(node)) && node == parent->first)	\
		node = parent;						\
									\
	return rb_hole_addr_to_node(parent);				\
}

DECLARE_NEXT_HOLE_ADDR(next_hole_high_addr, rb_left, rb_right)
DECLARE_NEXT_HOLE_ADDR(next_hole_low_addr, rb_right, rb_left)

static struct drm_mm_node *
next_hole(struct drm_mm *mm,
	  struct drm_mm_node *node,
	  u64 size,
	  enum drm_mm_insert_mode mode)
{
	switch (mode) {
	default:
	case DRM_MM_INSERT_BEST:
		return rb_hole_size_to_node(rb_prev(&node->rb_hole_size));

	case DRM_MM_INSERT_LOW:
		return next_hole_low_addr(node, size);

	case DRM_MM_INSERT_HIGH:
		return next_hole_high_addr(node, size);

	case DRM_MM_INSERT_EVICT:
		node = list_next_entry(node, hole_stack);
		return &node->hole_stack == &mm->hole_stack ? NULL : node;
	}
}

/**
 * drm_mm_reserve_node - insert an pre-initialized node
 * @mm: drm_mm allocator to insert @node into
 * @node: drm_mm_node to insert
 *
 * This functions inserts an already set-up &drm_mm_node into the allocator,
 * meaning that start, size and color must be set by the caller. All other
 * fields must be cleared to 0. This is useful to initialize the allocator with
 * preallocated objects which must be set-up before the range allocator can be
 * set-up, e.g. when taking over a firmware framebuffer.
 *
 * Returns:
 * 0 on success, -ENOSPC if there's no hole where @node is.
 */
int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
{
	struct drm_mm_node *hole;
	u64 hole_start, hole_end;
	u64 adj_start, adj_end;
	u64 end;

	end = node->start + node->size;
	if (unlikely(end <= node->start))
		return -ENOSPC;

	/* Find the relevant hole to add our node to */
	hole = find_hole_addr(mm, node->start, 0);
	if (!hole)
		return -ENOSPC;

	adj_start = hole_start = __drm_mm_hole_node_start(hole);
	adj_end = hole_end = hole_start + hole->hole_size;

	if (mm->color_adjust)
		mm->color_adjust(hole, node->color, &adj_start, &adj_end);

	if (adj_start > node->start || adj_end < end)
		return -ENOSPC;

	node->mm = mm;

	__set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags);
	list_add(&node->node_list, &hole->node_list);
	drm_mm_interval_tree_add_node(hole, node);
	node->hole_size = 0;

	rm_hole(hole);
	if (node->start > hole_start)
		add_hole(hole);
	if (end < hole_end)
		add_hole(node);

	save_stack(node);
	return 0;
}
EXPORT_SYMBOL(drm_mm_reserve_node);

static u64 rb_to_hole_size_or_zero(struct rb_node *rb)
{
	return rb ? rb_to_hole_size(rb) : 0;
}

/**
 * drm_mm_insert_node_in_range - ranged search for space and insert @node
 * @mm: drm_mm to allocate from
 * @node: preallocate node to insert
 * @size: size of the allocation
 * @alignment: alignment of the allocation
 * @color: opaque tag value to use for this node
 * @range_start: start of the allowed range for this node
 * @range_end: end of the allowed range for this node
 * @mode: fine-tune the allocation search and placement
 *
 * The preallocated @node must be cleared to 0.
 *
 * Returns:
 * 0 on success, -ENOSPC if there's no suitable hole.
 */
int drm_mm_insert_node_in_range(struct drm_mm * const mm,
				struct drm_mm_node * const node,
				u64 size, u64 alignment,
				unsigned long color,
				u64 range_start, u64 range_end,
				enum drm_mm_insert_mode mode)
{
	struct drm_mm_node *hole;
	u64 remainder_mask;
	bool once;

	DRM_MM_BUG_ON(range_start > range_end);

	if (unlikely(size == 0 || range_end - range_start < size))
		return -ENOSPC;

	if (rb_to_hole_size_or_zero(rb_first_cached(&mm->holes_size)) < size)
		return -ENOSPC;

	if (alignment <= 1)
		alignment = 0;

	once = mode & DRM_MM_INSERT_ONCE;
	mode &= ~DRM_MM_INSERT_ONCE;

	remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
	for (hole = first_hole(mm, range_start, range_end, size, mode);
	     hole;
	     hole = once ? NULL : next_hole(mm, hole, size, mode)) {
		u64 hole_start = __drm_mm_hole_node_start(hole);
		u64 hole_end = hole_start + hole->hole_size;
		u64 adj_start, adj_end;
		u64 col_start, col_end;

		if (mode == DRM_MM_INSERT_LOW && hole_start >= range_end)
			break;

		if (mode == DRM_MM_INSERT_HIGH && hole_end <= range_start)
			break;

		col_start = hole_start;
		col_end = hole_end;
		if (mm->color_adjust)
			mm->color_adjust(hole, color, &col_start, &col_end);

		adj_start = max(col_start, range_start);
		adj_end = min(col_end, range_end);

		if (adj_end <= adj_start || adj_end - adj_start < size)
			continue;

		if (mode == DRM_MM_INSERT_HIGH)
			adj_start = adj_end - size;

		if (alignment) {
			u64 rem;

			if (likely(remainder_mask))
				rem = adj_start & remainder_mask;
			else
				div64_u64_rem(adj_start, alignment, &rem);
			if (rem) {
				adj_start -= rem;
				if (mode != DRM_MM_INSERT_HIGH)
					adj_start += alignment;

				if (adj_start < max(col_start, range_start) ||
				    min(col_end, range_end) - adj_start < size)
					continue;

				if (adj_end <= adj_start ||
				    adj_end - adj_start < size)
					continue;
			}
		}

		node->mm = mm;
		node->size = size;
		node->start = adj_start;
		node->color = color;
		node->hole_size = 0;

		__set_bit(DRM_MM_NODE_ALLOCATED_BIT, &node->flags);
		list_add(&node->node_list, &hole->node_list);
		drm_mm_interval_tree_add_node(hole, node);

		rm_hole(hole);
		if (adj_start > hole_start)
			add_hole(hole);
		if (adj_start + size < hole_end)
			add_hole(node);

		save_stack(node);
		return 0;
	}

	return -ENOSPC;
}
EXPORT_SYMBOL(drm_mm_insert_node_in_range);

static inline bool drm_mm_node_scanned_block(const struct drm_mm_node *node)
{
	return test_bit(DRM_MM_NODE_SCANNED_BIT, &node->flags);
}

/**
 * drm_mm_remove_node - Remove a memory node from the allocator.
 * @node: drm_mm_node to remove
 *
 * This just removes a node from its drm_mm allocator. The node does not need to
 * be cleared again before it can be re-inserted into this or any other drm_mm
 * allocator. It is a bug to call this function on a unallocated node.
 */
void drm_mm_remove_node(struct drm_mm_node *node)
{
	struct drm_mm *mm = node->mm;
	struct drm_mm_node *prev_node;

	DRM_MM_BUG_ON(!drm_mm_node_allocated(node));
	DRM_MM_BUG_ON(drm_mm_node_scanned_block(node));

	prev_node = list_prev_entry(node, node_list);

	if (drm_mm_hole_follows(node))
		rm_hole(node);

	drm_mm_interval_tree_remove(node, &mm->interval_tree);
	list_del(&node->node_list);

	if (drm_mm_hole_follows(prev_node))
		rm_hole(prev_node);
	add_hole(prev_node);

	clear_bit_unlock(DRM_MM_NODE_ALLOCATED_BIT, &node->flags);
}
EXPORT_SYMBOL(drm_mm_remove_node);

/**
 * drm_mm_replace_node - move an allocation from @old to @new
 * @old: drm_mm_node to remove from the allocator
 * @new: drm_mm_node which should inherit @old's allocation
 *
 * This is useful for when drivers embed the drm_mm_node structure and hence
 * can't move allocations by reassigning pointers. It's a combination of remove
 * and insert with the guarantee that the allocation start will match.
 */
void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)
{
	struct drm_mm *mm = old->mm;

	DRM_MM_BUG_ON(!drm_mm_node_allocated(old));

	*new = *old;

	__set_bit(DRM_MM_NODE_ALLOCATED_BIT, &new->flags);
	list_replace(&old->node_list, &new->node_list);
	rb_replace_node_cached(&old->rb, &new->rb, &mm->interval_tree);

	if (drm_mm_hole_follows(old)) {
		list_replace(&old->hole_stack, &new->hole_stack);
		rb_replace_node_cached(&old->rb_hole_size,
				       &new->rb_hole_size,
				       &mm->holes_size);
		rb_replace_node(&old->rb_hole_addr,
				&new->rb_hole_addr,
				&mm->holes_addr);
	}

	clear_bit_unlock(DRM_MM_NODE_ALLOCATED_BIT, &old->flags);
}
EXPORT_SYMBOL(drm_mm_replace_node);

/**
 * DOC: lru scan roster
 *
 * Very often GPUs need to have continuous allocations for a given object. When
 * evicting objects to make space for a new one it is therefore not most
 * efficient when we simply start to select all objects from the tail of an LRU
 * until there's a suitable hole: Especially for big objects or nodes that
 * otherwise have special allocation constraints there's a good chance we evict
 * lots of (smaller) objects unnecessarily.
 *
 * The DRM range allocator supports this use-case through the scanning
 * interfaces. First a scan operation needs to be initialized with
 * drm_mm_scan_init() or drm_mm_scan_init_with_range(). The driver adds
 * objects to the roster, probably by walking an LRU list, but this can be
 * freely implemented. Eviction candidates are added using
 * drm_mm_scan_add_block() until a suitable hole is found or there are no
 * further evictable objects. Eviction roster metadata is tracked in &struct
 * drm_mm_scan.
 *
 * The driver must walk through all objects again in exactly the reverse
 * order to restore the allocator state. Note that while the allocator is used
 * in the scan mode no other operation is allowed.
 *
 * Finally the driver evicts all objects selected (drm_mm_scan_remove_block()
 * reported true) in the scan, and any overlapping nodes after color adjustment
 * (drm_mm_scan_color_evict()). Adding and removing an object is O(1), and
 * since freeing a node is also O(1) the overall complexity is
 * O(scanned_objects). So like the free stack which needs to be walked before a
 * scan operation even begins this is linear in the number of objects. It
 * doesn't seem to hurt too badly.
 */

/**
 * drm_mm_scan_init_with_range - initialize range-restricted lru scanning
 * @scan: scan state
 * @mm: drm_mm to scan
 * @size: size of the allocation
 * @alignment: alignment of the allocation
 * @color: opaque tag value to use for the allocation
 * @start: start of the allowed range for the allocation
 * @end: end of the allowed range for the allocation
 * @mode: fine-tune the allocation search and placement
 *
 * This simply sets up the scanning routines with the parameters for the desired
 * hole.
 *
 * Warning:
 * As long as the scan list is non-empty, no other operations than
 * adding/removing nodes to/from the scan list are allowed.
 */
void drm_mm_scan_init_with_range(struct drm_mm_scan *scan,
				 struct drm_mm *mm,
				 u64 size,
				 u64 alignment,
				 unsigned long color,
				 u64 start,
				 u64 end,
				 enum drm_mm_insert_mode mode)
{
	DRM_MM_BUG_ON(start >= end);
	DRM_MM_BUG_ON(!size || size > end - start);
	DRM_MM_BUG_ON(mm->scan_active);

	scan->mm = mm;

	if (alignment <= 1)
		alignment = 0;

	scan->color = color;
	scan->alignment = alignment;
	scan->remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
	scan->size = size;
	scan->mode = mode;

	DRM_MM_BUG_ON(end <= start);
	scan->range_start = start;
	scan->range_end = end;

	scan->hit_start = U64_MAX;
	scan->hit_end = 0;
}
EXPORT_SYMBOL(drm_mm_scan_init_with_range);

/**
 * drm_mm_scan_add_block - add a node to the scan list
 * @scan: the active drm_mm scanner
 * @node: drm_mm_node to add
 *
 * Add a node to the scan list that might be freed to make space for the desired
 * hole.
 *
 * Returns:
 * True if a hole has been found, false otherwise.
 */
bool drm_mm_scan_add_block(struct drm_mm_scan *scan,
			   struct drm_mm_node *node)
{
	struct drm_mm *mm = scan->mm;
	struct drm_mm_node *hole;
	u64 hole_start, hole_end;
	u64 col_start, col_end;
	u64 adj_start, adj_end;

	DRM_MM_BUG_ON(node->mm != mm);
	DRM_MM_BUG_ON(!drm_mm_node_allocated(node));
	DRM_MM_BUG_ON(drm_mm_node_scanned_block(node));
	__set_bit(DRM_MM_NODE_SCANNED_BIT, &node->flags);
	mm->scan_active++;

	/* Remove this block from the node_list so that we enlarge the hole
	 * (distance between the end of our previous node and the start of
	 * or next), without poisoning the link so that we can restore it
	 * later in drm_mm_scan_remove_block().
	 */
	hole = list_prev_entry(node, node_list);
	DRM_MM_BUG_ON(list_next_entry(hole, node_list) != node);
	__list_del_entry(&node->node_list);

	hole_start = __drm_mm_hole_node_start(hole);
	hole_end = __drm_mm_hole_node_end(hole);

	col_start = hole_start;
	col_end = hole_end;
	if (mm->color_adjust)
		mm->color_adjust(hole, scan->color, &col_start, &col_end);

	adj_start = max(col_start, scan->range_start);
	adj_end = min(col_end, scan->range_end);
	if (adj_end <= adj_start || adj_end - adj_start < scan->size)
		return false;

	if (scan->mode == DRM_MM_INSERT_HIGH)
		adj_start = adj_end - scan->size;

	if (scan->alignment) {
		u64 rem;

		if (likely(scan->remainder_mask))
			rem = adj_start & scan->remainder_mask;
		else
			div64_u64_rem(adj_start, scan->alignment, &rem);
		if (rem) {
			adj_start -= rem;
			if (scan->mode != DRM_MM_INSERT_HIGH)
				adj_start += scan->alignment;
			if (adj_start < max(col_start, scan->range_start) ||
			    min(col_end, scan->range_end) - adj_start < scan->size)
				return false;

			if (adj_end <= adj_start ||
			    adj_end - adj_start < scan->size)
				return false;
		}
	}

	scan->hit_start = adj_start;
	scan->hit_end = adj_start + scan->size;

	DRM_MM_BUG_ON(scan->hit_start >= scan->hit_end);
	DRM_MM_BUG_ON(scan->hit_start < hole_start);
	DRM_MM_BUG_ON(scan->hit_end > hole_end);

	return true;
}
EXPORT_SYMBOL(drm_mm_scan_add_block);

/**
 * drm_mm_scan_remove_block - remove a node from the scan list
 * @scan: the active drm_mm scanner
 * @node: drm_mm_node to remove
 *
 * Nodes **must** be removed in exactly the reverse order from the scan list as
 * they have been added (e.g. using list_add() as they are added and then
 * list_for_each() over that eviction list to remove), otherwise the internal
 * state of the memory manager will be corrupted.
 *
 * When the scan list is empty, the selected memory nodes can be freed. An
 * immediately following drm_mm_insert_node_in_range_generic() or one of the
 * simpler versions of that function with !DRM_MM_SEARCH_BEST will then return
 * the just freed block (because it's at the top of the free_stack list).
 *
 * Returns:
 * True if this block should be evicted, false otherwise. Will always
 * return false when no hole has been found.
 */
bool drm_mm_scan_remove_block(struct drm_mm_scan *scan,
			      struct drm_mm_node *node)
{
	struct drm_mm_node *prev_node;

	DRM_MM_BUG_ON(node->mm != scan->mm);
	DRM_MM_BUG_ON(!drm_mm_node_scanned_block(node));
	__clear_bit(DRM_MM_NODE_SCANNED_BIT, &node->flags);

	DRM_MM_BUG_ON(!node->mm->scan_active);
	node->mm->scan_active--;

	/* During drm_mm_scan_add_block() we decoupled this node leaving
	 * its pointers intact. Now that the caller is walking back along
	 * the eviction list we can restore this block into its rightful
	 * place on the full node_list. To confirm that the caller is walking
	 * backwards correctly we check that prev_node->next == node->next,
	 * i.e. both believe the same node should be on the other side of the
	 * hole.
	 */
	prev_node = list_prev_entry(node, node_list);
	DRM_MM_BUG_ON(list_next_entry(prev_node, node_list) !=
		      list_next_entry(node, node_list));
	list_add(&node->node_list, &prev_node->node_list);

	return (node->start + node->size > scan->hit_start &&
		node->start < scan->hit_end);
}
EXPORT_SYMBOL(drm_mm_scan_remove_block);

/**
 * drm_mm_scan_color_evict - evict overlapping nodes on either side of hole
 * @scan: drm_mm scan with target hole
 *
 * After completing an eviction scan and removing the selected nodes, we may
 * need to remove a few more nodes from either side of the target hole if
 * mm.color_adjust is being used.
 *
 * Returns:
 * A node to evict, or NULL if there are no overlapping nodes.
 */
struct drm_mm_node *drm_mm_scan_color_evict(struct drm_mm_scan *scan)
{
	struct drm_mm *mm = scan->mm;
	struct drm_mm_node *hole;
	u64 hole_start, hole_end;

	DRM_MM_BUG_ON(list_empty(&mm->hole_stack));

	if (!mm->color_adjust)
		return NULL;

	/*
	 * The hole found during scanning should ideally be the first element
	 * in the hole_stack list, but due to side-effects in the driver it
	 * may not be.
	 */
	list_for_each_entry(hole, &mm->hole_stack, hole_stack) {
		hole_start = __drm_mm_hole_node_start(hole);
		hole_end = hole_start + hole->hole_size;

		if (hole_start <= scan->hit_start &&
		    hole_end >= scan->hit_end)
			break;
	}

	/* We should only be called after we found the hole previously */
	DRM_MM_BUG_ON(&hole->hole_stack == &mm->hole_stack);
	if (unlikely(&hole->hole_stack == &mm->hole_stack))
		return NULL;

	DRM_MM_BUG_ON(hole_start > scan->hit_start);
	DRM_MM_BUG_ON(hole_end < scan->hit_end);

	mm->color_adjust(hole, scan->color, &hole_start, &hole_end);
	if (hole_start > scan->hit_start)
		return hole;
	if (hole_end < scan->hit_end)
		return list_next_entry(hole, node_list);

	return NULL;
}
EXPORT_SYMBOL(drm_mm_scan_color_evict);

/**
 * drm_mm_init - initialize a drm-mm allocator
 * @mm: the drm_mm structure to initialize
 * @start: start of the range managed by @mm
 * @size: end of the range managed by @mm
 *
 * Note that @mm must be cleared to 0 before calling this function.
 */
void drm_mm_init(struct drm_mm *mm, u64 start, u64 size)
{
	DRM_MM_BUG_ON(start + size <= start);

	mm->color_adjust = NULL;

	INIT_LIST_HEAD(&mm->hole_stack);
	mm->interval_tree = RB_ROOT_CACHED;
	mm->holes_size = RB_ROOT_CACHED;
	mm->holes_addr = RB_ROOT;

	/* Clever trick to avoid a special case in the free hole tracking. */
	INIT_LIST_HEAD(&mm->head_node.node_list);
	mm->head_node.flags = 0;
	mm->head_node.mm = mm;
	mm->head_node.start = start + size;
	mm->head_node.size = -size;
	add_hole(&mm->head_node);

	mm->scan_active = 0;
}
EXPORT_SYMBOL(drm_mm_init);

/**
 * drm_mm_takedown - clean up a drm_mm allocator
 * @mm: drm_mm allocator to clean up
 *
 * Note that it is a bug to call this function on an allocator which is not
 * clean.
 */
void drm_mm_takedown(struct drm_mm *mm)
{
	if (WARN(!drm_mm_clean(mm),
		 "Memory manager not clean during takedown.\n"))
		show_leaks(mm);
}
EXPORT_SYMBOL(drm_mm_takedown);

static u64 drm_mm_dump_hole(struct drm_printer *p, const struct drm_mm_node *entry)
{
	u64 start, size;

	size = entry->hole_size;
	if (size) {
		start = drm_mm_hole_node_start(entry);
		drm_printf(p, "%#018llx-%#018llx: %llu: free\n",
			   start, start + size, size);
	}

	return size;
}
/**
 * drm_mm_print - print allocator state
 * @mm: drm_mm allocator to print
 * @p: DRM printer to use
 */
void drm_mm_print(const struct drm_mm *mm, struct drm_printer *p)
{
	const struct drm_mm_node *entry;
	u64 total_used = 0, total_free = 0, total = 0;

	total_free += drm_mm_dump_hole(p, &mm->head_node);

	drm_mm_for_each_node(entry, mm) {
		drm_printf(p, "%#018llx-%#018llx: %llu: used\n", entry->start,
			   entry->start + entry->size, entry->size);
		total_used += entry->size;
		total_free += drm_mm_dump_hole(p, entry);
	}
	total = total_free + total_used;

	drm_printf(p, "total: %llu, used %llu free %llu\n", total,
		   total_used, total_free);
}
EXPORT_SYMBOL(drm_mm_print);