root/drivers/gpu/drm/drm_mm.c

DEFINITIONS

1. save_stack
2. show_leaks
3. save_stack
4. show_leaks
5. INTERVAL_TREE_DEFINE
6. drm_mm_interval_tree_add_node
7. rb_to_hole_size
8. insert_hole_size
9. add_hole
10. rm_hole
11. rb_hole_size_to_node
12. rb_hole_addr_to_node
13. rb_hole_size
14. best_hole
15. find_hole
16. first_hole
17. next_hole
18. drm_mm_reserve_node
19. rb_to_hole_size_or_zero
20. drm_mm_insert_node_in_range
21. drm_mm_remove_node
22. drm_mm_replace_node
23. drm_mm_scan_init_with_range
24. drm_mm_scan_add_block
25. drm_mm_scan_remove_block
26. drm_mm_scan_color_evict
27. drm_mm_init
28. drm_mm_takedown
29. drm_mm_dump_hole
30. drm_mm_print

   1 /**************************************************************************
   2  *
   3  * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.
   4  * Copyright 2016 Intel Corporation
   5  * All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the
   9  * "Software"), to deal in the Software without restriction, including
  10  * without limitation the rights to use, copy, modify, merge, publish,
  11  * distribute, sub license, and/or sell copies of the Software, and to
  12  * permit persons to whom the Software is furnished to do so, subject to
  13  * the following conditions:
  14  *
  15  * The above copyright notice and this permission notice (including the
  16  * next paragraph) shall be included in all copies or substantial portions
  17  * of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  22  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  23  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  24  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  25  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  26  *
  27  *
  28  **************************************************************************/
  29 
  30 /*
  31  * Generic simple memory manager implementation. Intended to be used as a base
  32  * class implementation for more advanced memory managers.
  33  *
  34  * Note that the algorithm used is quite simple and there might be substantial
  35  * performance gains if a smarter free list is implemented. Currently it is
  36  * just an unordered stack of free regions. This could easily be improved if
  37  * an RB-tree is used instead. At least if we expect heavy fragmentation.
  38  *
  39  * Aligned allocations can also see improvement.
  40  *
  41  * Authors:
  42  * Thomas Hellström <thomas-at-tungstengraphics-dot-com>
  43  */
  44 
  45 #include <linux/export.h>
  46 #include <linux/interval_tree_generic.h>
  47 #include <linux/seq_file.h>
  48 #include <linux/slab.h>
  49 #include <linux/stacktrace.h>
  50 
  51 #include <drm/drm_mm.h>
  52 
  53 /**
  54  * DOC: Overview
  55  *
  56  * drm_mm provides a simple range allocator. The drivers are free to use the
  57  * resource allocator from the linux core if it suits them, the upside of drm_mm
  58  * is that it's in the DRM core. Which means that it's easier to extend for
  59  * some of the crazier special purpose needs of gpus.
  60  *
  61  * The main data struct is &drm_mm, allocations are tracked in &drm_mm_node.
  62  * Drivers are free to embed either of them into their own suitable
  63  * datastructures. drm_mm itself will not do any memory allocations of its own,
  64  * so if drivers choose not to embed nodes they need to still allocate them
  65  * themselves.
  66  *
  67  * The range allocator also supports reservation of preallocated blocks. This is
  68  * useful for taking over initial mode setting configurations from the firmware,
  69  * where an object needs to be created which exactly matches the firmware's
  70  * scanout target. As long as the range is still free it can be inserted anytime
  71  * after the allocator is initialized, which helps with avoiding looped
  72  * dependencies in the driver load sequence.
  73  *
  74  * drm_mm maintains a stack of most recently freed holes, which of all
  75  * simplistic datastructures seems to be a fairly decent approach to clustering
  76  * allocations and avoiding too much fragmentation. This means free space
  77  * searches are O(num_holes). Given that all the fancy features drm_mm supports
  78  * something better would be fairly complex and since gfx thrashing is a fairly
  79  * steep cliff not a real concern. Removing a node again is O(1).
  80  *
  81  * drm_mm supports a few features: Alignment and range restrictions can be
  82  * supplied. Furthermore every &drm_mm_node has a color value (which is just an
  83  * opaque unsigned long) which in conjunction with a driver callback can be used
  84  * to implement sophisticated placement restrictions. The i915 DRM driver uses
  85  * this to implement guard pages between incompatible caching domains in the
  86  * graphics TT.
  87  *
  88  * Two behaviors are supported for searching and allocating: bottom-up and
  89  * top-down. The default is bottom-up. Top-down allocation can be used if the
  90  * memory area has different restrictions, or just to reduce fragmentation.
  91  *
  92  * Finally iteration helpers to walk all nodes and all holes are provided as are
  93  * some basic allocator dumpers for debugging.
  94  *
  95  * Note that this range allocator is not thread-safe, drivers need to protect
  96  * modifications with their own locking. The idea behind this is that for a full
  97  * memory manager additional data needs to be protected anyway, hence internal
  98  * locking would be fully redundant.
  99  */
 100 
 101 #ifdef CONFIG_DRM_DEBUG_MM
 102 #include <linux/stackdepot.h>
 103 
 104 #define STACKDEPTH 32
 105 #define BUFSZ 4096
 106 
 107 static noinline void save_stack(struct drm_mm_node *node)
 108 {
 109         unsigned long entries[STACKDEPTH];
 110         unsigned int n;
 111 
 112         n = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
 113 
 114         /* May be called under spinlock, so avoid sleeping */
 115         node->stack = stack_depot_save(entries, n, GFP_NOWAIT);
 116 }
 117 
 118 static void show_leaks(struct drm_mm *mm)
 119 {
 120         struct drm_mm_node *node;
 121         unsigned long *entries;
 122         unsigned int nr_entries;
 123         char *buf;
 124 
 125         buf = kmalloc(BUFSZ, GFP_KERNEL);
 126         if (!buf)
 127                 return;
 128 
 129         list_for_each_entry(node, drm_mm_nodes(mm), node_list) {
 130                 if (!node->stack) {
 131                         DRM_ERROR("node [%08llx + %08llx]: unknown owner\n",
 132                                   node->start, node->size);
 133                         continue;
 134                 }
 135 
 136                 nr_entries = stack_depot_fetch(node->stack, &entries);
 137                 stack_trace_snprint(buf, BUFSZ, entries, nr_entries, 0);
 138                 DRM_ERROR("node [%08llx + %08llx]: inserted at\n%s",
 139                           node->start, node->size, buf);
 140         }
 141 
 142         kfree(buf);
 143 }
 144 
 145 #undef STACKDEPTH
 146 #undef BUFSZ
 147 #else
 148 static void save_stack(struct drm_mm_node *node) { }
 149 static void show_leaks(struct drm_mm *mm) { }
 150 #endif
 151 
 152 #define START(node) ((node)->start)
 153 #define LAST(node)  ((node)->start + (node)->size - 1)
 154 
 155 INTERVAL_TREE_DEFINE(struct drm_mm_node, rb,
 156                      u64, __subtree_last,
 157                      START, LAST, static inline, drm_mm_interval_tree)
 158 
 159 struct drm_mm_node *
 160 __drm_mm_interval_first(const struct drm_mm *mm, u64 start, u64 last)
 161 {
 162         return drm_mm_interval_tree_iter_first((struct rb_root_cached *)&mm->interval_tree,
 163                                                start, last) ?: (struct drm_mm_node *)&mm->head_node;
 164 }
 165 EXPORT_SYMBOL(__drm_mm_interval_first);
 166 
 167 static void drm_mm_interval_tree_add_node(struct drm_mm_node *hole_node,
 168                                           struct drm_mm_node *node)
 169 {
 170         struct drm_mm *mm = hole_node->mm;
 171         struct rb_node **link, *rb;
 172         struct drm_mm_node *parent;
 173         bool leftmost;
 174 
 175         node->__subtree_last = LAST(node);
 176 
 177         if (hole_node->allocated) {
 178                 rb = &hole_node->rb;
 179                 while (rb) {
 180                         parent = rb_entry(rb, struct drm_mm_node, rb);
 181                         if (parent->__subtree_last >= node->__subtree_last)
 182                                 break;
 183 
 184                         parent->__subtree_last = node->__subtree_last;
 185                         rb = rb_parent(rb);
 186                 }
 187 
 188                 rb = &hole_node->rb;
 189                 link = &hole_node->rb.rb_right;
 190                 leftmost = false;
 191         } else {
 192                 rb = NULL;
 193                 link = &mm->interval_tree.rb_root.rb_node;
 194                 leftmost = true;
 195         }
 196 
 197         while (*link) {
 198                 rb = *link;
 199                 parent = rb_entry(rb, struct drm_mm_node, rb);
 200                 if (parent->__subtree_last < node->__subtree_last)
 201                         parent->__subtree_last = node->__subtree_last;
 202                 if (node->start < parent->start) {
 203                         link = &parent->rb.rb_left;
 204                 } else {
 205                         link = &parent->rb.rb_right;
 206                         leftmost = false;
 207                 }
 208         }
 209 
 210         rb_link_node(&node->rb, rb, link);
 211         rb_insert_augmented_cached(&node->rb, &mm->interval_tree, leftmost,
 212                                    &drm_mm_interval_tree_augment);
 213 }
 214 
 215 #define RB_INSERT(root, member, expr) do { \
 216         struct rb_node **link = &root.rb_node, *rb = NULL; \
 217         u64 x = expr(node); \
 218         while (*link) { \
 219                 rb = *link; \
 220                 if (x < expr(rb_entry(rb, struct drm_mm_node, member))) \
 221                         link = &rb->rb_left; \
 222                 else \
 223                         link = &rb->rb_right; \
 224         } \
 225         rb_link_node(&node->member, rb, link); \
 226         rb_insert_color(&node->member, &root); \
 227 } while (0)
 228 
 229 #define HOLE_SIZE(NODE) ((NODE)->hole_size)
 230 #define HOLE_ADDR(NODE) (__drm_mm_hole_node_start(NODE))
 231 
 232 static u64 rb_to_hole_size(struct rb_node *rb)
 233 {
 234         return rb_entry(rb, struct drm_mm_node, rb_hole_size)->hole_size;
 235 }
 236 
 237 static void insert_hole_size(struct rb_root_cached *root,
 238                              struct drm_mm_node *node)
 239 {
 240         struct rb_node **link = &root->rb_root.rb_node, *rb = NULL;
 241         u64 x = node->hole_size;
 242         bool first = true;
 243 
 244         while (*link) {
 245                 rb = *link;
 246                 if (x > rb_to_hole_size(rb)) {
 247                         link = &rb->rb_left;
 248                 } else {
 249                         link = &rb->rb_right;
 250                         first = false;
 251                 }
 252         }
 253 
 254         rb_link_node(&node->rb_hole_size, rb, link);
 255         rb_insert_color_cached(&node->rb_hole_size, root, first);
 256 }
 257 
 258 static void add_hole(struct drm_mm_node *node)
 259 {
 260         struct drm_mm *mm = node->mm;
 261 
 262         node->hole_size =
 263                 __drm_mm_hole_node_end(node) - __drm_mm_hole_node_start(node);
 264         DRM_MM_BUG_ON(!drm_mm_hole_follows(node));
 265 
 266         insert_hole_size(&mm->holes_size, node);
 267         RB_INSERT(mm->holes_addr, rb_hole_addr, HOLE_ADDR);
 268 
 269         list_add(&node->hole_stack, &mm->hole_stack);
 270 }
 271 
 272 static void rm_hole(struct drm_mm_node *node)
 273 {
 274         DRM_MM_BUG_ON(!drm_mm_hole_follows(node));
 275 
 276         list_del(&node->hole_stack);
 277         rb_erase_cached(&node->rb_hole_size, &node->mm->holes_size);
 278         rb_erase(&node->rb_hole_addr, &node->mm->holes_addr);
 279         node->hole_size = 0;
 280 
 281         DRM_MM_BUG_ON(drm_mm_hole_follows(node));
 282 }
 283 
 284 static inline struct drm_mm_node *rb_hole_size_to_node(struct rb_node *rb)
 285 {
 286         return rb_entry_safe(rb, struct drm_mm_node, rb_hole_size);
 287 }
 288 
 289 static inline struct drm_mm_node *rb_hole_addr_to_node(struct rb_node *rb)
 290 {
 291         return rb_entry_safe(rb, struct drm_mm_node, rb_hole_addr);
 292 }
 293 
 294 static inline u64 rb_hole_size(struct rb_node *rb)
 295 {
 296         return rb_entry(rb, struct drm_mm_node, rb_hole_size)->hole_size;
 297 }
 298 
 299 static struct drm_mm_node *best_hole(struct drm_mm *mm, u64 size)
 300 {
 301         struct rb_node *rb = mm->holes_size.rb_root.rb_node;
 302         struct drm_mm_node *best = NULL;
 303 
 304         do {
 305                 struct drm_mm_node *node =
 306                         rb_entry(rb, struct drm_mm_node, rb_hole_size);
 307 
 308                 if (size <= node->hole_size) {
 309                         best = node;
 310                         rb = rb->rb_right;
 311                 } else {
 312                         rb = rb->rb_left;
 313                 }
 314         } while (rb);
 315 
 316         return best;
 317 }
 318 
 319 static struct drm_mm_node *find_hole(struct drm_mm *mm, u64 addr)
 320 {
 321         struct rb_node *rb = mm->holes_addr.rb_node;
 322         struct drm_mm_node *node = NULL;
 323 
 324         while (rb) {
 325                 u64 hole_start;
 326 
 327                 node = rb_hole_addr_to_node(rb);
 328                 hole_start = __drm_mm_hole_node_start(node);
 329 
 330                 if (addr < hole_start)
 331                         rb = node->rb_hole_addr.rb_left;
 332                 else if (addr > hole_start + node->hole_size)
 333                         rb = node->rb_hole_addr.rb_right;
 334                 else
 335                         break;
 336         }
 337 
 338         return node;
 339 }
 340 
 341 static struct drm_mm_node *
 342 first_hole(struct drm_mm *mm,
 343            u64 start, u64 end, u64 size,
 344            enum drm_mm_insert_mode mode)
 345 {
 346         switch (mode) {
 347         default:
 348         case DRM_MM_INSERT_BEST:
 349                 return best_hole(mm, size);
 350 
 351         case DRM_MM_INSERT_LOW:
 352                 return find_hole(mm, start);
 353 
 354         case DRM_MM_INSERT_HIGH:
 355                 return find_hole(mm, end);
 356 
 357         case DRM_MM_INSERT_EVICT:
 358                 return list_first_entry_or_null(&mm->hole_stack,
 359                                                 struct drm_mm_node,
 360                                                 hole_stack);
 361         }
 362 }
 363 
 364 static struct drm_mm_node *
 365 next_hole(struct drm_mm *mm,
 366           struct drm_mm_node *node,
 367           enum drm_mm_insert_mode mode)
 368 {
 369         switch (mode) {
 370         default:
 371         case DRM_MM_INSERT_BEST:
 372                 return rb_hole_size_to_node(rb_prev(&node->rb_hole_size));
 373 
 374         case DRM_MM_INSERT_LOW:
 375                 return rb_hole_addr_to_node(rb_next(&node->rb_hole_addr));
 376 
 377         case DRM_MM_INSERT_HIGH:
 378                 return rb_hole_addr_to_node(rb_prev(&node->rb_hole_addr));
 379 
 380         case DRM_MM_INSERT_EVICT:
 381                 node = list_next_entry(node, hole_stack);
 382                 return &node->hole_stack == &mm->hole_stack ? NULL : node;
 383         }
 384 }
 385 
 386 /**
 387  * drm_mm_reserve_node - insert an pre-initialized node
 388  * @mm: drm_mm allocator to insert @node into
 389  * @node: drm_mm_node to insert
 390  *
 391  * This functions inserts an already set-up &drm_mm_node into the allocator,
 392  * meaning that start, size and color must be set by the caller. All other
 393  * fields must be cleared to 0. This is useful to initialize the allocator with
 394  * preallocated objects which must be set-up before the range allocator can be
 395  * set-up, e.g. when taking over a firmware framebuffer.
 396  *
 397  * Returns:
 398  * 0 on success, -ENOSPC if there's no hole where @node is.
 399  */
 400 int drm_mm_reserve_node(struct drm_mm *mm, struct drm_mm_node *node)
 401 {
 402         u64 end = node->start + node->size;
 403         struct drm_mm_node *hole;
 404         u64 hole_start, hole_end;
 405         u64 adj_start, adj_end;
 406 
 407         end = node->start + node->size;
 408         if (unlikely(end <= node->start))
 409                 return -ENOSPC;
 410 
 411         /* Find the relevant hole to add our node to */
 412         hole = find_hole(mm, node->start);
 413         if (!hole)
 414                 return -ENOSPC;
 415 
 416         adj_start = hole_start = __drm_mm_hole_node_start(hole);
 417         adj_end = hole_end = hole_start + hole->hole_size;
 418 
 419         if (mm->color_adjust)
 420                 mm->color_adjust(hole, node->color, &adj_start, &adj_end);
 421 
 422         if (adj_start > node->start || adj_end < end)
 423                 return -ENOSPC;
 424 
 425         node->mm = mm;
 426 
 427         list_add(&node->node_list, &hole->node_list);
 428         drm_mm_interval_tree_add_node(hole, node);
 429         node->allocated = true;
 430         node->hole_size = 0;
 431 
 432         rm_hole(hole);
 433         if (node->start > hole_start)
 434                 add_hole(hole);
 435         if (end < hole_end)
 436                 add_hole(node);
 437 
 438         save_stack(node);
 439         return 0;
 440 }
 441 EXPORT_SYMBOL(drm_mm_reserve_node);
 442 
 443 static u64 rb_to_hole_size_or_zero(struct rb_node *rb)
 444 {
 445         return rb ? rb_to_hole_size(rb) : 0;
 446 }
 447 
 448 /**
 449  * drm_mm_insert_node_in_range - ranged search for space and insert @node
 450  * @mm: drm_mm to allocate from
 451  * @node: preallocate node to insert
 452  * @size: size of the allocation
 453  * @alignment: alignment of the allocation
 454  * @color: opaque tag value to use for this node
 455  * @range_start: start of the allowed range for this node
 456  * @range_end: end of the allowed range for this node
 457  * @mode: fine-tune the allocation search and placement
 458  *
 459  * The preallocated @node must be cleared to 0.
 460  *
 461  * Returns:
 462  * 0 on success, -ENOSPC if there's no suitable hole.
 463  */
 464 int drm_mm_insert_node_in_range(struct drm_mm * const mm,
 465                                 struct drm_mm_node * const node,
 466                                 u64 size, u64 alignment,
 467                                 unsigned long color,
 468                                 u64 range_start, u64 range_end,
 469                                 enum drm_mm_insert_mode mode)
 470 {
 471         struct drm_mm_node *hole;
 472         u64 remainder_mask;
 473         bool once;
 474 
 475         DRM_MM_BUG_ON(range_start > range_end);
 476 
 477         if (unlikely(size == 0 || range_end - range_start < size))
 478                 return -ENOSPC;
 479 
 480         if (rb_to_hole_size_or_zero(rb_first_cached(&mm->holes_size)) < size)
 481                 return -ENOSPC;
 482 
 483         if (alignment <= 1)
 484                 alignment = 0;
 485 
 486         once = mode & DRM_MM_INSERT_ONCE;
 487         mode &= ~DRM_MM_INSERT_ONCE;
 488 
 489         remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
 490         for (hole = first_hole(mm, range_start, range_end, size, mode);
 491              hole;
 492              hole = once ? NULL : next_hole(mm, hole, mode)) {
 493                 u64 hole_start = __drm_mm_hole_node_start(hole);
 494                 u64 hole_end = hole_start + hole->hole_size;
 495                 u64 adj_start, adj_end;
 496                 u64 col_start, col_end;
 497 
 498                 if (mode == DRM_MM_INSERT_LOW && hole_start >= range_end)
 499                         break;
 500 
 501                 if (mode == DRM_MM_INSERT_HIGH && hole_end <= range_start)
 502                         break;
 503 
 504                 col_start = hole_start;
 505                 col_end = hole_end;
 506                 if (mm->color_adjust)
 507                         mm->color_adjust(hole, color, &col_start, &col_end);
 508 
 509                 adj_start = max(col_start, range_start);
 510                 adj_end = min(col_end, range_end);
 511 
 512                 if (adj_end <= adj_start || adj_end - adj_start < size)
 513                         continue;
 514 
 515                 if (mode == DRM_MM_INSERT_HIGH)
 516                         adj_start = adj_end - size;
 517 
 518                 if (alignment) {
 519                         u64 rem;
 520 
 521                         if (likely(remainder_mask))
 522                                 rem = adj_start & remainder_mask;
 523                         else
 524                                 div64_u64_rem(adj_start, alignment, &rem);
 525                         if (rem) {
 526                                 adj_start -= rem;
 527                                 if (mode != DRM_MM_INSERT_HIGH)
 528                                         adj_start += alignment;
 529 
 530                                 if (adj_start < max(col_start, range_start) ||
 531                                     min(col_end, range_end) - adj_start < size)
 532                                         continue;
 533 
 534                                 if (adj_end <= adj_start ||
 535                                     adj_end - adj_start < size)
 536                                         continue;
 537                         }
 538                 }
 539 
 540                 node->mm = mm;
 541                 node->size = size;
 542                 node->start = adj_start;
 543                 node->color = color;
 544                 node->hole_size = 0;
 545 
 546                 list_add(&node->node_list, &hole->node_list);
 547                 drm_mm_interval_tree_add_node(hole, node);
 548                 node->allocated = true;
 549 
 550                 rm_hole(hole);
 551                 if (adj_start > hole_start)
 552                         add_hole(hole);
 553                 if (adj_start + size < hole_end)
 554                         add_hole(node);
 555 
 556                 save_stack(node);
 557                 return 0;
 558         }
 559 
 560         return -ENOSPC;
 561 }
 562 EXPORT_SYMBOL(drm_mm_insert_node_in_range);
 563 
 564 /**
 565  * drm_mm_remove_node - Remove a memory node from the allocator.
 566  * @node: drm_mm_node to remove
 567  *
 568  * This just removes a node from its drm_mm allocator. The node does not need to
 569  * be cleared again before it can be re-inserted into this or any other drm_mm
 570  * allocator. It is a bug to call this function on a unallocated node.
 571  */
 572 void drm_mm_remove_node(struct drm_mm_node *node)
 573 {
 574         struct drm_mm *mm = node->mm;
 575         struct drm_mm_node *prev_node;
 576 
 577         DRM_MM_BUG_ON(!node->allocated);
 578         DRM_MM_BUG_ON(node->scanned_block);
 579 
 580         prev_node = list_prev_entry(node, node_list);
 581 
 582         if (drm_mm_hole_follows(node))
 583                 rm_hole(node);
 584 
 585         drm_mm_interval_tree_remove(node, &mm->interval_tree);
 586         list_del(&node->node_list);
 587         node->allocated = false;
 588 
 589         if (drm_mm_hole_follows(prev_node))
 590                 rm_hole(prev_node);
 591         add_hole(prev_node);
 592 }
 593 EXPORT_SYMBOL(drm_mm_remove_node);
 594 
 595 /**
 596  * drm_mm_replace_node - move an allocation from @old to @new
 597  * @old: drm_mm_node to remove from the allocator
 598  * @new: drm_mm_node which should inherit @old's allocation
 599  *
 600  * This is useful for when drivers embed the drm_mm_node structure and hence
 601  * can't move allocations by reassigning pointers. It's a combination of remove
 602  * and insert with the guarantee that the allocation start will match.
 603  */
 604 void drm_mm_replace_node(struct drm_mm_node *old, struct drm_mm_node *new)
 605 {
 606         struct drm_mm *mm = old->mm;
 607 
 608         DRM_MM_BUG_ON(!old->allocated);
 609 
 610         *new = *old;
 611 
 612         list_replace(&old->node_list, &new->node_list);
 613         rb_replace_node_cached(&old->rb, &new->rb, &mm->interval_tree);
 614 
 615         if (drm_mm_hole_follows(old)) {
 616                 list_replace(&old->hole_stack, &new->hole_stack);
 617                 rb_replace_node_cached(&old->rb_hole_size,
 618                                        &new->rb_hole_size,
 619                                        &mm->holes_size);
 620                 rb_replace_node(&old->rb_hole_addr,
 621                                 &new->rb_hole_addr,
 622                                 &mm->holes_addr);
 623         }
 624 
 625         old->allocated = false;
 626         new->allocated = true;
 627 }
 628 EXPORT_SYMBOL(drm_mm_replace_node);
 629 
 630 /**
 631  * DOC: lru scan roster
 632  *
 633  * Very often GPUs need to have continuous allocations for a given object. When
 634  * evicting objects to make space for a new one it is therefore not most
 635  * efficient when we simply start to select all objects from the tail of an LRU
 636  * until there's a suitable hole: Especially for big objects or nodes that
 637  * otherwise have special allocation constraints there's a good chance we evict
 638  * lots of (smaller) objects unnecessarily.
 639  *
 640  * The DRM range allocator supports this use-case through the scanning
 641  * interfaces. First a scan operation needs to be initialized with
 642  * drm_mm_scan_init() or drm_mm_scan_init_with_range(). The driver adds
 643  * objects to the roster, probably by walking an LRU list, but this can be
 644  * freely implemented. Eviction candiates are added using
 645  * drm_mm_scan_add_block() until a suitable hole is found or there are no
 646  * further evictable objects. Eviction roster metadata is tracked in &struct
 647  * drm_mm_scan.
 648  *
 649  * The driver must walk through all objects again in exactly the reverse
 650  * order to restore the allocator state. Note that while the allocator is used
 651  * in the scan mode no other operation is allowed.
 652  *
 653  * Finally the driver evicts all objects selected (drm_mm_scan_remove_block()
 654  * reported true) in the scan, and any overlapping nodes after color adjustment
 655  * (drm_mm_scan_color_evict()). Adding and removing an object is O(1), and
 656  * since freeing a node is also O(1) the overall complexity is
 657  * O(scanned_objects). So like the free stack which needs to be walked before a
 658  * scan operation even begins this is linear in the number of objects. It
 659  * doesn't seem to hurt too badly.
 660  */
 661 
 662 /**
 663  * drm_mm_scan_init_with_range - initialize range-restricted lru scanning
 664  * @scan: scan state
 665  * @mm: drm_mm to scan
 666  * @size: size of the allocation
 667  * @alignment: alignment of the allocation
 668  * @color: opaque tag value to use for the allocation
 669  * @start: start of the allowed range for the allocation
 670  * @end: end of the allowed range for the allocation
 671  * @mode: fine-tune the allocation search and placement
 672  *
 673  * This simply sets up the scanning routines with the parameters for the desired
 674  * hole.
 675  *
 676  * Warning:
 677  * As long as the scan list is non-empty, no other operations than
 678  * adding/removing nodes to/from the scan list are allowed.
 679  */
 680 void drm_mm_scan_init_with_range(struct drm_mm_scan *scan,
 681                                  struct drm_mm *mm,
 682                                  u64 size,
 683                                  u64 alignment,
 684                                  unsigned long color,
 685                                  u64 start,
 686                                  u64 end,
 687                                  enum drm_mm_insert_mode mode)
 688 {
 689         DRM_MM_BUG_ON(start >= end);
 690         DRM_MM_BUG_ON(!size || size > end - start);
 691         DRM_MM_BUG_ON(mm->scan_active);
 692 
 693         scan->mm = mm;
 694 
 695         if (alignment <= 1)
 696                 alignment = 0;
 697 
 698         scan->color = color;
 699         scan->alignment = alignment;
 700         scan->remainder_mask = is_power_of_2(alignment) ? alignment - 1 : 0;
 701         scan->size = size;
 702         scan->mode = mode;
 703 
 704         DRM_MM_BUG_ON(end <= start);
 705         scan->range_start = start;
 706         scan->range_end = end;
 707 
 708         scan->hit_start = U64_MAX;
 709         scan->hit_end = 0;
 710 }
 711 EXPORT_SYMBOL(drm_mm_scan_init_with_range);
 712 
 713 /**
 714  * drm_mm_scan_add_block - add a node to the scan list
 715  * @scan: the active drm_mm scanner
 716  * @node: drm_mm_node to add
 717  *
 718  * Add a node to the scan list that might be freed to make space for the desired
 719  * hole.
 720  *
 721  * Returns:
 722  * True if a hole has been found, false otherwise.
 723  */
 724 bool drm_mm_scan_add_block(struct drm_mm_scan *scan,
 725                            struct drm_mm_node *node)
 726 {
 727         struct drm_mm *mm = scan->mm;
 728         struct drm_mm_node *hole;
 729         u64 hole_start, hole_end;
 730         u64 col_start, col_end;
 731         u64 adj_start, adj_end;
 732 
 733         DRM_MM_BUG_ON(node->mm != mm);
 734         DRM_MM_BUG_ON(!node->allocated);
 735         DRM_MM_BUG_ON(node->scanned_block);
 736         node->scanned_block = true;
 737         mm->scan_active++;
 738 
 739         /* Remove this block from the node_list so that we enlarge the hole
 740          * (distance between the end of our previous node and the start of
 741          * or next), without poisoning the link so that we can restore it
 742          * later in drm_mm_scan_remove_block().
 743          */
 744         hole = list_prev_entry(node, node_list);
 745         DRM_MM_BUG_ON(list_next_entry(hole, node_list) != node);
 746         __list_del_entry(&node->node_list);
 747 
 748         hole_start = __drm_mm_hole_node_start(hole);
 749         hole_end = __drm_mm_hole_node_end(hole);
 750 
 751         col_start = hole_start;
 752         col_end = hole_end;
 753         if (mm->color_adjust)
 754                 mm->color_adjust(hole, scan->color, &col_start, &col_end);
 755 
 756         adj_start = max(col_start, scan->range_start);
 757         adj_end = min(col_end, scan->range_end);
 758         if (adj_end <= adj_start || adj_end - adj_start < scan->size)
 759                 return false;
 760 
 761         if (scan->mode == DRM_MM_INSERT_HIGH)
 762                 adj_start = adj_end - scan->size;
 763 
 764         if (scan->alignment) {
 765                 u64 rem;
 766 
 767                 if (likely(scan->remainder_mask))
 768                         rem = adj_start & scan->remainder_mask;
 769                 else
 770                         div64_u64_rem(adj_start, scan->alignment, &rem);
 771                 if (rem) {
 772                         adj_start -= rem;
 773                         if (scan->mode != DRM_MM_INSERT_HIGH)
 774                                 adj_start += scan->alignment;
 775                         if (adj_start < max(col_start, scan->range_start) ||
 776                             min(col_end, scan->range_end) - adj_start < scan->size)
 777                                 return false;
 778 
 779                         if (adj_end <= adj_start ||
 780                             adj_end - adj_start < scan->size)
 781                                 return false;
 782                 }
 783         }
 784 
 785         scan->hit_start = adj_start;
 786         scan->hit_end = adj_start + scan->size;
 787 
 788         DRM_MM_BUG_ON(scan->hit_start >= scan->hit_end);
 789         DRM_MM_BUG_ON(scan->hit_start < hole_start);
 790         DRM_MM_BUG_ON(scan->hit_end > hole_end);
 791 
 792         return true;
 793 }
 794 EXPORT_SYMBOL(drm_mm_scan_add_block);
 795 
 796 /**
 797  * drm_mm_scan_remove_block - remove a node from the scan list
 798  * @scan: the active drm_mm scanner
 799  * @node: drm_mm_node to remove
 800  *
 801  * Nodes **must** be removed in exactly the reverse order from the scan list as
 802  * they have been added (e.g. using list_add() as they are added and then
 803  * list_for_each() over that eviction list to remove), otherwise the internal
 804  * state of the memory manager will be corrupted.
 805  *
 806  * When the scan list is empty, the selected memory nodes can be freed. An
 807  * immediately following drm_mm_insert_node_in_range_generic() or one of the
 808  * simpler versions of that function with !DRM_MM_SEARCH_BEST will then return
 809  * the just freed block (because it's at the top of the free_stack list).
 810  *
 811  * Returns:
 812  * True if this block should be evicted, false otherwise. Will always
 813  * return false when no hole has been found.
 814  */
 815 bool drm_mm_scan_remove_block(struct drm_mm_scan *scan,
 816                               struct drm_mm_node *node)
 817 {
 818         struct drm_mm_node *prev_node;
 819 
 820         DRM_MM_BUG_ON(node->mm != scan->mm);
 821         DRM_MM_BUG_ON(!node->scanned_block);
 822         node->scanned_block = false;
 823 
 824         DRM_MM_BUG_ON(!node->mm->scan_active);
 825         node->mm->scan_active--;
 826 
 827         /* During drm_mm_scan_add_block() we decoupled this node leaving
 828          * its pointers intact. Now that the caller is walking back along
 829          * the eviction list we can restore this block into its rightful
 830          * place on the full node_list. To confirm that the caller is walking
 831          * backwards correctly we check that prev_node->next == node->next,
 832          * i.e. both believe the same node should be on the other side of the
 833          * hole.
 834          */
 835         prev_node = list_prev_entry(node, node_list);
 836         DRM_MM_BUG_ON(list_next_entry(prev_node, node_list) !=
 837                       list_next_entry(node, node_list));
 838         list_add(&node->node_list, &prev_node->node_list);
 839 
 840         return (node->start + node->size > scan->hit_start &&
 841                 node->start < scan->hit_end);
 842 }
 843 EXPORT_SYMBOL(drm_mm_scan_remove_block);
 844 
 845 /**
 846  * drm_mm_scan_color_evict - evict overlapping nodes on either side of hole
 847  * @scan: drm_mm scan with target hole
 848  *
 849  * After completing an eviction scan and removing the selected nodes, we may
 850  * need to remove a few more nodes from either side of the target hole if
 851  * mm.color_adjust is being used.
 852  *
 853  * Returns:
 854  * A node to evict, or NULL if there are no overlapping nodes.
 855  */
 856 struct drm_mm_node *drm_mm_scan_color_evict(struct drm_mm_scan *scan)
 857 {
 858         struct drm_mm *mm = scan->mm;
 859         struct drm_mm_node *hole;
 860         u64 hole_start, hole_end;
 861 
 862         DRM_MM_BUG_ON(list_empty(&mm->hole_stack));
 863 
 864         if (!mm->color_adjust)
 865                 return NULL;
 866 
 867         /*
 868          * The hole found during scanning should ideally be the first element
 869          * in the hole_stack list, but due to side-effects in the driver it
 870          * may not be.
 871          */
 872         list_for_each_entry(hole, &mm->hole_stack, hole_stack) {
 873                 hole_start = __drm_mm_hole_node_start(hole);
 874                 hole_end = hole_start + hole->hole_size;
 875 
 876                 if (hole_start <= scan->hit_start &&
 877                     hole_end >= scan->hit_end)
 878                         break;
 879         }
 880 
 881         /* We should only be called after we found the hole previously */
 882         DRM_MM_BUG_ON(&hole->hole_stack == &mm->hole_stack);
 883         if (unlikely(&hole->hole_stack == &mm->hole_stack))
 884                 return NULL;
 885 
 886         DRM_MM_BUG_ON(hole_start > scan->hit_start);
 887         DRM_MM_BUG_ON(hole_end < scan->hit_end);
 888 
 889         mm->color_adjust(hole, scan->color, &hole_start, &hole_end);
 890         if (hole_start > scan->hit_start)
 891                 return hole;
 892         if (hole_end < scan->hit_end)
 893                 return list_next_entry(hole, node_list);
 894 
 895         return NULL;
 896 }
 897 EXPORT_SYMBOL(drm_mm_scan_color_evict);
 898 
 899 /**
 900  * drm_mm_init - initialize a drm-mm allocator
 901  * @mm: the drm_mm structure to initialize
 902  * @start: start of the range managed by @mm
 903  * @size: end of the range managed by @mm
 904  *
 905  * Note that @mm must be cleared to 0 before calling this function.
 906  */
 907 void drm_mm_init(struct drm_mm *mm, u64 start, u64 size)
 908 {
 909         DRM_MM_BUG_ON(start + size <= start);
 910 
 911         mm->color_adjust = NULL;
 912 
 913         INIT_LIST_HEAD(&mm->hole_stack);
 914         mm->interval_tree = RB_ROOT_CACHED;
 915         mm->holes_size = RB_ROOT_CACHED;
 916         mm->holes_addr = RB_ROOT;
 917 
 918         /* Clever trick to avoid a special case in the free hole tracking. */
 919         INIT_LIST_HEAD(&mm->head_node.node_list);
 920         mm->head_node.allocated = false;
 921         mm->head_node.mm = mm;
 922         mm->head_node.start = start + size;
 923         mm->head_node.size = -size;
 924         add_hole(&mm->head_node);
 925 
 926         mm->scan_active = 0;
 927 }
 928 EXPORT_SYMBOL(drm_mm_init);
 929 
 930 /**
 931  * drm_mm_takedown - clean up a drm_mm allocator
 932  * @mm: drm_mm allocator to clean up
 933  *
 934  * Note that it is a bug to call this function on an allocator which is not
 935  * clean.
 936  */
 937 void drm_mm_takedown(struct drm_mm *mm)
 938 {
 939         if (WARN(!drm_mm_clean(mm),
 940                  "Memory manager not clean during takedown.\n"))
 941                 show_leaks(mm);
 942 }
 943 EXPORT_SYMBOL(drm_mm_takedown);
 944 
 945 static u64 drm_mm_dump_hole(struct drm_printer *p, const struct drm_mm_node *entry)
 946 {
 947         u64 start, size;
 948 
 949         size = entry->hole_size;
 950         if (size) {
 951                 start = drm_mm_hole_node_start(entry);
 952                 drm_printf(p, "%#018llx-%#018llx: %llu: free\n",
 953                            start, start + size, size);
 954         }
 955 
 956         return size;
 957 }
 958 /**
 959  * drm_mm_print - print allocator state
 960  * @mm: drm_mm allocator to print
 961  * @p: DRM printer to use
 962  */
 963 void drm_mm_print(const struct drm_mm *mm, struct drm_printer *p)
 964 {
 965         const struct drm_mm_node *entry;
 966         u64 total_used = 0, total_free = 0, total = 0;
 967 
 968         total_free += drm_mm_dump_hole(p, &mm->head_node);
 969 
 970         drm_mm_for_each_node(entry, mm) {
 971                 drm_printf(p, "%#018llx-%#018llx: %llu: used\n", entry->start,
 972                            entry->start + entry->size, entry->size);
 973                 total_used += entry->size;
 974                 total_free += drm_mm_dump_hole(p, entry);
 975         }
 976         total = total_free + total_used;
 977 
 978         drm_printf(p, "total: %llu, used %llu free %llu\n", total,
 979                    total_used, total_free);
 980 }
 981 EXPORT_SYMBOL(drm_mm_print);