sys/vm/vm_radix.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2013 EMC Corp.
   5  * Copyright (c) 2011 Jeffrey Roberson <jeff@freebsd.org>
   6  * Copyright (c) 2008 Mayur Shardul <mayur.shardul@gmail.com>
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  *
  30  */
  31
  32 /*
  33  * Path-compressed radix trie implementation.
  34  * The following code is not generalized into a general purpose library
  35  * because there are way too many parameters embedded that should really
  36  * be decided by the library consumers.  At the same time, consumers
  37  * of this code must achieve highest possible performance.
  38  *
  39  * The implementation takes into account the following rationale:
  40  * - Size of the nodes should be as small as possible but still big enough
  41  *   to avoid a large maximum depth for the trie.  This is a balance
  42  *   between the necessity to not wire too much physical memory for the nodes
  43  *   and the necessity to avoid too much cache pollution during the trie
  44  *   operations.
  45  * - There is not a huge bias toward the number of lookup operations over
  46  *   the number of insert and remove operations.  This basically implies
  47  *   that optimizations supposedly helping one operation but hurting the
  48  *   other might be carefully evaluated.
  49  * - On average not many nodes are expected to be fully populated, hence
  50  *   level compression may just complicate things.
  51  */
  52
  53 #include <sys/cdefs.h>
  54 __FBSDID("$FreeBSD$");
  55
  56 #include "opt_ddb.h"
  57
  58 #include <sys/param.h>
  59 #include <sys/systm.h>
  60 #include <sys/kernel.h>
  61 #include <sys/vmmeter.h>
  62
  63 #include <vm/uma.h>
  64 #include <vm/vm.h>
  65 #include <vm/vm_param.h>
  66 #include <vm/vm_page.h>
  67 #include <vm/vm_radix.h>
  68
  69 #ifdef DDB
  70 #include <ddb/ddb.h>
  71 #endif
  72
  73 /*
  74  * These widths should allow the pointers to a node's children to fit within
  75  * a single cache line.  The extra levels from a narrow width should not be
  76  * a problem thanks to path compression.
  77  */
  78 #ifdef __LP64__
  79 #define VM_RADIX_WIDTH  4
  80 #else
  81 #define VM_RADIX_WIDTH  3
  82 #endif
  83
  84 #define VM_RADIX_COUNT  (1 << VM_RADIX_WIDTH)
  85 #define VM_RADIX_MASK   (VM_RADIX_COUNT - 1)
  86 #define VM_RADIX_LIMIT                                                  \
  87         (howmany(sizeof(vm_pindex_t) * NBBY, VM_RADIX_WIDTH) - 1)
  88
  89 /* Flag bits stored in node pointers. */
  90 #define VM_RADIX_ISLEAF 0x1
  91 #define VM_RADIX_FLAGS  0x1
  92 #define VM_RADIX_PAD    VM_RADIX_FLAGS
  93
  94 /* Returns one unit associated with specified level. */
  95 #define VM_RADIX_UNITLEVEL(lev)                                         \
  96         ((vm_pindex_t)1 << ((lev) * VM_RADIX_WIDTH))
  97
  98 struct vm_radix_node {
  99         vm_pindex_t      rn_owner;                      /* Owner of record. */
 100         uint16_t         rn_count;                      /* Valid children. */
 101         uint16_t         rn_clev;                       /* Current level. */
 102         void            *rn_child[VM_RADIX_COUNT];      /* Child nodes. */
 103 };
 104
 105 static uma_zone_t vm_radix_node_zone;
 106
 107 /*
 108  * Allocate a radix node.
 109  */
 110 static __inline struct vm_radix_node *
 111 vm_radix_node_get(vm_pindex_t owner, uint16_t count, uint16_t clevel)
 112 {
 113         struct vm_radix_node *rnode;
 114
 115         rnode = uma_zalloc(vm_radix_node_zone, M_NOWAIT);
 116         if (rnode == NULL)
 117                 return (NULL);
 118         rnode->rn_owner = owner;
 119         rnode->rn_count = count;
 120         rnode->rn_clev = clevel;
 121         return (rnode);
 122 }
 123
 124 /*
 125  * Free radix node.
 126  */
 127 static __inline void
 128 vm_radix_node_put(struct vm_radix_node *rnode)
 129 {
 130
 131         uma_zfree(vm_radix_node_zone, rnode);
 132 }
 133
 134 /*
 135  * Return the position in the array for a given level.
 136  */
 137 static __inline int
 138 vm_radix_slot(vm_pindex_t index, uint16_t level)
 139 {
 140
 141         return ((index >> (level * VM_RADIX_WIDTH)) & VM_RADIX_MASK);
 142 }
 143
 144 /* Trims the key after the specified level. */
 145 static __inline vm_pindex_t
 146 vm_radix_trimkey(vm_pindex_t index, uint16_t level)
 147 {
 148         vm_pindex_t ret;
 149
 150         ret = index;
 151         if (level > 0) {
 152                 ret >>= level * VM_RADIX_WIDTH;
 153                 ret <<= level * VM_RADIX_WIDTH;
 154         }
 155         return (ret);
 156 }
 157
 158 /*
 159  * Get the root node for a radix tree.
 160  */
 161 static __inline struct vm_radix_node *
 162 vm_radix_getroot(struct vm_radix *rtree)
 163 {
 164
 165         return ((struct vm_radix_node *)rtree->rt_root);
 166 }
 167
 168 /*
 169  * Set the root node for a radix tree.
 170  */
 171 static __inline void
 172 vm_radix_setroot(struct vm_radix *rtree, struct vm_radix_node *rnode)
 173 {
 174
 175         rtree->rt_root = (uintptr_t)rnode;
 176 }
 177
 178 /*
 179  * Returns TRUE if the specified radix node is a leaf and FALSE otherwise.
 180  */
 181 static __inline boolean_t
 182 vm_radix_isleaf(struct vm_radix_node *rnode)
 183 {
 184
 185         return (((uintptr_t)rnode & VM_RADIX_ISLEAF) != 0);
 186 }
 187
 188 /*
 189  * Returns the associated page extracted from rnode.
 190  */
 191 static __inline vm_page_t
 192 vm_radix_topage(struct vm_radix_node *rnode)
 193 {
 194
 195         return ((vm_page_t)((uintptr_t)rnode & ~VM_RADIX_FLAGS));
 196 }
 197
 198 /*
 199  * Adds the page as a child of the provided node.
 200  */
 201 static __inline void
 202 vm_radix_addpage(struct vm_radix_node *rnode, vm_pindex_t index, uint16_t clev,
 203     vm_page_t page)
 204 {
 205         int slot;
 206
 207         slot = vm_radix_slot(index, clev);
 208         rnode->rn_child[slot] = (void *)((uintptr_t)page | VM_RADIX_ISLEAF);
 209 }
 210
 211 /*
 212  * Returns the slot where two keys differ.
 213  * It cannot accept 2 equal keys.
 214  */
 215 static __inline uint16_t
 216 vm_radix_keydiff(vm_pindex_t index1, vm_pindex_t index2)
 217 {
 218         uint16_t clev;
 219
 220         KASSERT(index1 != index2, ("%s: passing the same key value %jx",
 221             __func__, (uintmax_t)index1));
 222
 223         index1 ^= index2;
 224         for (clev = VM_RADIX_LIMIT;; clev--)
 225                 if (vm_radix_slot(index1, clev) != 0)
 226                         return (clev);
 227 }
 228
 229 /*
 230  * Returns TRUE if it can be determined that key does not belong to the
 231  * specified rnode.  Otherwise, returns FALSE.
 232  */
 233 static __inline boolean_t
 234 vm_radix_keybarr(struct vm_radix_node *rnode, vm_pindex_t idx)
 235 {
 236
 237         if (rnode->rn_clev < VM_RADIX_LIMIT) {
 238                 idx = vm_radix_trimkey(idx, rnode->rn_clev + 1);
 239                 return (idx != rnode->rn_owner);
 240         }
 241         return (FALSE);
 242 }
 243
 244 /*
 245  * Internal helper for vm_radix_reclaim_allnodes().
 246  * This function is recursive.
 247  */
 248 static void
 249 vm_radix_reclaim_allnodes_int(struct vm_radix_node *rnode)
 250 {
 251         int slot;
 252
 253         KASSERT(rnode->rn_count <= VM_RADIX_COUNT,
 254             ("vm_radix_reclaim_allnodes_int: bad count in rnode %p", rnode));
 255         for (slot = 0; rnode->rn_count != 0; slot++) {
 256                 if (rnode->rn_child[slot] == NULL)
 257                         continue;
 258                 if (!vm_radix_isleaf(rnode->rn_child[slot]))
 259                         vm_radix_reclaim_allnodes_int(rnode->rn_child[slot]);
 260                 rnode->rn_child[slot] = NULL;
 261                 rnode->rn_count--;
 262         }
 263         vm_radix_node_put(rnode);
 264 }
 265
 266 #ifdef INVARIANTS
 267 /*
 268  * Radix node zone destructor.
 269  */
 270 static void
 271 vm_radix_node_zone_dtor(void *mem, int size __unused, void *arg __unused)
 272 {
 273         struct vm_radix_node *rnode;
 274         int slot;
 275
 276         rnode = mem;
 277         KASSERT(rnode->rn_count == 0,
 278             ("vm_radix_node_put: rnode %p has %d children", rnode,
 279             rnode->rn_count));
 280         for (slot = 0; slot < VM_RADIX_COUNT; slot++)
 281                 KASSERT(rnode->rn_child[slot] == NULL,
 282                     ("vm_radix_node_put: rnode %p has a child", rnode));
 283 }
 284 #endif
 285
 286 static int
 287 vm_radix_node_zone_init(void *mem, int size __unused, int flags __unused)
 288 {
 289         struct vm_radix_node *rnode;
 290
 291         rnode = mem;
 292         bzero(rnode, sizeof(*rnode));
 293         return (0);
 294 }
 295
 296 #ifndef UMA_MD_SMALL_ALLOC
 297 void vm_radix_reserve_kva(void);
 298 /*
 299  * Reserve the KVA necessary to satisfy the node allocation.
 300  * This is mandatory in architectures not supporting direct
 301  * mapping as they will need otherwise to carve into the kernel maps for
 302  * every node allocation, resulting into deadlocks for consumers already
 303  * working with kernel maps.
 304  */
 305 void
 306 vm_radix_reserve_kva(void)
 307 {
 308
 309         /*
 310          * Calculate the number of reserved nodes, discounting the pages that
 311          * are needed to store them.
 312          */
 313         if (!uma_zone_reserve_kva(vm_radix_node_zone,
 314             ((vm_paddr_t)vm_cnt.v_page_count * PAGE_SIZE) / (PAGE_SIZE +
 315             sizeof(struct vm_radix_node))))
 316                 panic("%s: unable to reserve KVA", __func__);
 317 }
 318 #endif
 319
 320 /*
 321  * Initialize the UMA slab zone.
 322  */
 323 void
 324 vm_radix_zinit(void)
 325 {
 326
 327         vm_radix_node_zone = uma_zcreate("RADIX NODE",
 328             sizeof(struct vm_radix_node), NULL,
 329 #ifdef INVARIANTS
 330             vm_radix_node_zone_dtor,
 331 #else
 332             NULL,
 333 #endif
 334             vm_radix_node_zone_init, NULL, VM_RADIX_PAD, UMA_ZONE_VM);
 335 }
 336
 337 /*
 338  * Inserts the key-value pair into the trie.
 339  * Panics if the key already exists.
 340  */
 341 int
 342 vm_radix_insert(struct vm_radix *rtree, vm_page_t page)
 343 {
 344         vm_pindex_t index, newind;
 345         void **parentp;
 346         struct vm_radix_node *rnode, *tmp;
 347         vm_page_t m;
 348         int slot;
 349         uint16_t clev;
 350
 351         index = page->pindex;
 352
 353         /*
 354          * The owner of record for root is not really important because it
 355          * will never be used.
 356          */
 357         rnode = vm_radix_getroot(rtree);
 358         if (rnode == NULL) {
 359                 rtree->rt_root = (uintptr_t)page | VM_RADIX_ISLEAF;
 360                 return (0);
 361         }
 362         parentp = (void **)&rtree->rt_root;
 363         for (;;) {
 364                 if (vm_radix_isleaf(rnode)) {
 365                         m = vm_radix_topage(rnode);
 366                         if (m->pindex == index)
 367                                 panic("%s: key %jx is already present",
 368                                     __func__, (uintmax_t)index);
 369                         clev = vm_radix_keydiff(m->pindex, index);
 370                         tmp = vm_radix_node_get(vm_radix_trimkey(index,
 371                             clev + 1), 2, clev);
 372                         if (tmp == NULL)
 373                                 return (ENOMEM);
 374                         *parentp = tmp;
 375                         vm_radix_addpage(tmp, index, clev, page);
 376                         vm_radix_addpage(tmp, m->pindex, clev, m);
 377                         return (0);
 378                 } else if (vm_radix_keybarr(rnode, index))
 379                         break;
 380                 slot = vm_radix_slot(index, rnode->rn_clev);
 381                 if (rnode->rn_child[slot] == NULL) {
 382                         rnode->rn_count++;
 383                         vm_radix_addpage(rnode, index, rnode->rn_clev, page);
 384                         return (0);
 385                 }
 386                 parentp = &rnode->rn_child[slot];
 387                 rnode = rnode->rn_child[slot];
 388         }
 389
 390         /*
 391          * A new node is needed because the right insertion level is reached.
 392          * Setup the new intermediate node and add the 2 children: the
 393          * new object and the older edge.
 394          */
 395         newind = rnode->rn_owner;
 396         clev = vm_radix_keydiff(newind, index);
 397         tmp = vm_radix_node_get(vm_radix_trimkey(index, clev + 1), 2, clev);
 398         if (tmp == NULL)
 399                 return (ENOMEM);
 400         *parentp = tmp;
 401         vm_radix_addpage(tmp, index, clev, page);
 402         slot = vm_radix_slot(newind, clev);
 403         tmp->rn_child[slot] = rnode;
 404         return (0);
 405 }
 406
 407 /*
 408  * Returns TRUE if the specified radix tree contains a single leaf and FALSE
 409  * otherwise.
 410  */
 411 boolean_t
 412 vm_radix_is_singleton(struct vm_radix *rtree)
 413 {
 414         struct vm_radix_node *rnode;
 415
 416         rnode = vm_radix_getroot(rtree);
 417         if (rnode == NULL)
 418                 return (FALSE);
 419         return (vm_radix_isleaf(rnode));
 420 }
 421
 422 /*
 423  * Returns the value stored at the index.  If the index is not present,
 424  * NULL is returned.
 425  */
 426 vm_page_t
 427 vm_radix_lookup(struct vm_radix *rtree, vm_pindex_t index)
 428 {
 429         struct vm_radix_node *rnode;
 430         vm_page_t m;
 431         int slot;
 432
 433         rnode = vm_radix_getroot(rtree);
 434         while (rnode != NULL) {
 435                 if (vm_radix_isleaf(rnode)) {
 436                         m = vm_radix_topage(rnode);
 437                         if (m->pindex == index)
 438                                 return (m);
 439                         else
 440                                 break;
 441                 } else if (vm_radix_keybarr(rnode, index))
 442                         break;
 443                 slot = vm_radix_slot(index, rnode->rn_clev);
 444                 rnode = rnode->rn_child[slot];
 445         }
 446         return (NULL);
 447 }
 448
 449 /*
 450  * Look up the nearest entry at a position bigger than or equal to index.
 451  */
 452 vm_page_t
 453 vm_radix_lookup_ge(struct vm_radix *rtree, vm_pindex_t index)
 454 {
 455         struct vm_radix_node *stack[VM_RADIX_LIMIT];
 456         vm_pindex_t inc;
 457         vm_page_t m;
 458         struct vm_radix_node *child, *rnode;
 459 #ifdef INVARIANTS
 460         int loops = 0;
 461 #endif
 462         int slot, tos;
 463
 464         rnode = vm_radix_getroot(rtree);
 465         if (rnode == NULL)
 466                 return (NULL);
 467         else if (vm_radix_isleaf(rnode)) {
 468                 m = vm_radix_topage(rnode);
 469                 if (m->pindex >= index)
 470                         return (m);
 471                 else
 472                         return (NULL);
 473         }
 474         tos = 0;
 475         for (;;) {
 476                 /*
 477                  * If the keys differ before the current bisection node,
 478                  * then the search key might rollback to the earliest
 479                  * available bisection node or to the smallest key
 480                  * in the current node (if the owner is bigger than the
 481                  * search key).
 482                  */
 483                 if (vm_radix_keybarr(rnode, index)) {
 484                         if (index > rnode->rn_owner) {
 485 ascend:
 486                                 KASSERT(++loops < 1000,
 487                                     ("vm_radix_lookup_ge: too many loops"));
 488
 489                                 /*
 490                                  * Pop nodes from the stack until either the
 491                                  * stack is empty or a node that could have a
 492                                  * matching descendant is found.
 493                                  */
 494                                 do {
 495                                         if (tos == 0)
 496                                                 return (NULL);
 497                                         rnode = stack[--tos];
 498                                 } while (vm_radix_slot(index,
 499                                     rnode->rn_clev) == (VM_RADIX_COUNT - 1));
 500
 501                                 /*
 502                                  * The following computation cannot overflow
 503                                  * because index's slot at the current level
 504                                  * is less than VM_RADIX_COUNT - 1.
 505                                  */
 506                                 index = vm_radix_trimkey(index,
 507                                     rnode->rn_clev);
 508                                 index += VM_RADIX_UNITLEVEL(rnode->rn_clev);
 509                         } else
 510                                 index = rnode->rn_owner;
 511                         KASSERT(!vm_radix_keybarr(rnode, index),
 512                             ("vm_radix_lookup_ge: keybarr failed"));
 513                 }
 514                 slot = vm_radix_slot(index, rnode->rn_clev);
 515                 child = rnode->rn_child[slot];
 516                 if (vm_radix_isleaf(child)) {
 517                         m = vm_radix_topage(child);
 518                         if (m->pindex >= index)
 519                                 return (m);
 520                 } else if (child != NULL)
 521                         goto descend;
 522
 523                 /*
 524                  * Look for an available edge or page within the current
 525                  * bisection node.
 526                  */
 527                 if (slot < (VM_RADIX_COUNT - 1)) {
 528                         inc = VM_RADIX_UNITLEVEL(rnode->rn_clev);
 529                         index = vm_radix_trimkey(index, rnode->rn_clev);
 530                         do {
 531                                 index += inc;
 532                                 slot++;
 533                                 child = rnode->rn_child[slot];
 534                                 if (vm_radix_isleaf(child)) {
 535                                         m = vm_radix_topage(child);
 536                                         if (m->pindex >= index)
 537                                                 return (m);
 538                                 } else if (child != NULL)
 539                                         goto descend;
 540                         } while (slot < (VM_RADIX_COUNT - 1));
 541                 }
 542                 KASSERT(child == NULL || vm_radix_isleaf(child),
 543                     ("vm_radix_lookup_ge: child is radix node"));
 544
 545                 /*
 546                  * If a page or edge bigger than the search slot is not found
 547                  * in the current node, ascend to the next higher-level node.
 548                  */
 549                 goto ascend;
 550 descend:
 551                 KASSERT(rnode->rn_clev > 0,
 552                     ("vm_radix_lookup_ge: pushing leaf's parent"));
 553                 KASSERT(tos < VM_RADIX_LIMIT,
 554                     ("vm_radix_lookup_ge: stack overflow"));
 555                 stack[tos++] = rnode;
 556                 rnode = child;
 557         }
 558 }
 559
 560 /*
 561  * Look up the nearest entry at a position less than or equal to index.
 562  */
 563 vm_page_t
 564 vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index)
 565 {
 566         struct vm_radix_node *stack[VM_RADIX_LIMIT];
 567         vm_pindex_t inc;
 568         vm_page_t m;
 569         struct vm_radix_node *child, *rnode;
 570 #ifdef INVARIANTS
 571         int loops = 0;
 572 #endif
 573         int slot, tos;
 574
 575         rnode = vm_radix_getroot(rtree);
 576         if (rnode == NULL)
 577                 return (NULL);
 578         else if (vm_radix_isleaf(rnode)) {
 579                 m = vm_radix_topage(rnode);
 580                 if (m->pindex <= index)
 581                         return (m);
 582                 else
 583                         return (NULL);
 584         }
 585         tos = 0;
 586         for (;;) {
 587                 /*
 588                  * If the keys differ before the current bisection node,
 589                  * then the search key might rollback to the earliest
 590                  * available bisection node or to the largest key
 591                  * in the current node (if the owner is smaller than the
 592                  * search key).
 593                  */
 594                 if (vm_radix_keybarr(rnode, index)) {
 595                         if (index > rnode->rn_owner) {
 596                                 index = rnode->rn_owner + VM_RADIX_COUNT *
 597                                     VM_RADIX_UNITLEVEL(rnode->rn_clev);
 598                         } else {
 599 ascend:
 600                                 KASSERT(++loops < 1000,
 601                                     ("vm_radix_lookup_le: too many loops"));
 602
 603                                 /*
 604                                  * Pop nodes from the stack until either the
 605                                  * stack is empty or a node that could have a
 606                                  * matching descendant is found.
 607                                  */
 608                                 do {
 609                                         if (tos == 0)
 610                                                 return (NULL);
 611                                         rnode = stack[--tos];
 612                                 } while (vm_radix_slot(index,
 613                                     rnode->rn_clev) == 0);
 614
 615                                 /*
 616                                  * The following computation cannot overflow
 617                                  * because index's slot at the current level
 618                                  * is greater than 0.
 619                                  */
 620                                 index = vm_radix_trimkey(index,
 621                                     rnode->rn_clev);
 622                         }
 623                         index--;
 624                         KASSERT(!vm_radix_keybarr(rnode, index),
 625                             ("vm_radix_lookup_le: keybarr failed"));
 626                 }
 627                 slot = vm_radix_slot(index, rnode->rn_clev);
 628                 child = rnode->rn_child[slot];
 629                 if (vm_radix_isleaf(child)) {
 630                         m = vm_radix_topage(child);
 631                         if (m->pindex <= index)
 632                                 return (m);
 633                 } else if (child != NULL)
 634                         goto descend;
 635
 636                 /*
 637                  * Look for an available edge or page within the current
 638                  * bisection node.
 639                  */
 640                 if (slot > 0) {
 641                         inc = VM_RADIX_UNITLEVEL(rnode->rn_clev);
 642                         index |= inc - 1;
 643                         do {
 644                                 index -= inc;
 645                                 slot--;
 646                                 child = rnode->rn_child[slot];
 647                                 if (vm_radix_isleaf(child)) {
 648                                         m = vm_radix_topage(child);
 649                                         if (m->pindex <= index)
 650                                                 return (m);
 651                                 } else if (child != NULL)
 652                                         goto descend;
 653                         } while (slot > 0);
 654                 }
 655                 KASSERT(child == NULL || vm_radix_isleaf(child),
 656                     ("vm_radix_lookup_le: child is radix node"));
 657
 658                 /*
 659                  * If a page or edge smaller than the search slot is not found
 660                  * in the current node, ascend to the next higher-level node.
 661                  */
 662                 goto ascend;
 663 descend:
 664                 KASSERT(rnode->rn_clev > 0,
 665                     ("vm_radix_lookup_le: pushing leaf's parent"));
 666                 KASSERT(tos < VM_RADIX_LIMIT,
 667                     ("vm_radix_lookup_le: stack overflow"));
 668                 stack[tos++] = rnode;
 669                 rnode = child;
 670         }
 671 }
 672
 673 /*
 674  * Remove the specified index from the trie, and return the value stored at
 675  * that index.  If the index is not present, return NULL.
 676  */
 677 vm_page_t
 678 vm_radix_remove(struct vm_radix *rtree, vm_pindex_t index)
 679 {
 680         struct vm_radix_node *rnode, *parent;
 681         vm_page_t m;
 682         int i, slot;
 683
 684         rnode = vm_radix_getroot(rtree);
 685         if (vm_radix_isleaf(rnode)) {
 686                 m = vm_radix_topage(rnode);
 687                 if (m->pindex != index)
 688                         return (NULL);
 689                 vm_radix_setroot(rtree, NULL);
 690                 return (m);
 691         }
 692         parent = NULL;
 693         for (;;) {
 694                 if (rnode == NULL)
 695                         return (NULL);
 696                 slot = vm_radix_slot(index, rnode->rn_clev);
 697                 if (vm_radix_isleaf(rnode->rn_child[slot])) {
 698                         m = vm_radix_topage(rnode->rn_child[slot]);
 699                         if (m->pindex != index)
 700                                 return (NULL);
 701                         rnode->rn_child[slot] = NULL;
 702                         rnode->rn_count--;
 703                         if (rnode->rn_count > 1)
 704                                 return (m);
 705                         for (i = 0; i < VM_RADIX_COUNT; i++)
 706                                 if (rnode->rn_child[i] != NULL)
 707                                         break;
 708                         KASSERT(i != VM_RADIX_COUNT,
 709                             ("%s: invalid node configuration", __func__));
 710                         if (parent == NULL)
 711                                 vm_radix_setroot(rtree, rnode->rn_child[i]);
 712                         else {
 713                                 slot = vm_radix_slot(index, parent->rn_clev);
 714                                 KASSERT(parent->rn_child[slot] == rnode,
 715                                     ("%s: invalid child value", __func__));
 716                                 parent->rn_child[slot] = rnode->rn_child[i];
 717                         }
 718                         rnode->rn_count--;
 719                         rnode->rn_child[i] = NULL;
 720                         vm_radix_node_put(rnode);
 721                         return (m);
 722                 }
 723                 parent = rnode;
 724                 rnode = rnode->rn_child[slot];
 725         }
 726 }
 727
 728 /*
 729  * Remove and free all the nodes from the radix tree.
 730  * This function is recursive but there is a tight control on it as the
 731  * maximum depth of the tree is fixed.
 732  */
 733 void
 734 vm_radix_reclaim_allnodes(struct vm_radix *rtree)
 735 {
 736         struct vm_radix_node *root;
 737
 738         root = vm_radix_getroot(rtree);
 739         if (root == NULL)
 740                 return;
 741         vm_radix_setroot(rtree, NULL);
 742         if (!vm_radix_isleaf(root))
 743                 vm_radix_reclaim_allnodes_int(root);
 744 }
 745
 746 /*
 747  * Replace an existing page in the trie with another one.
 748  * Panics if there is not an old page in the trie at the new page's index.
 749  */
 750 vm_page_t
 751 vm_radix_replace(struct vm_radix *rtree, vm_page_t newpage)
 752 {
 753         struct vm_radix_node *rnode;
 754         vm_page_t m;
 755         vm_pindex_t index;
 756         int slot;
 757
 758         index = newpage->pindex;
 759         rnode = vm_radix_getroot(rtree);
 760         if (rnode == NULL)
 761                 panic("%s: replacing page on an empty trie", __func__);
 762         if (vm_radix_isleaf(rnode)) {
 763                 m = vm_radix_topage(rnode);
 764                 if (m->pindex != index)
 765                         panic("%s: original replacing root key not found",
 766                             __func__);
 767                 rtree->rt_root = (uintptr_t)newpage | VM_RADIX_ISLEAF;
 768                 return (m);
 769         }
 770         for (;;) {
 771                 slot = vm_radix_slot(index, rnode->rn_clev);
 772                 if (vm_radix_isleaf(rnode->rn_child[slot])) {
 773                         m = vm_radix_topage(rnode->rn_child[slot]);
 774                         if (m->pindex == index) {
 775                                 rnode->rn_child[slot] =
 776                                     (void *)((uintptr_t)newpage |
 777                                     VM_RADIX_ISLEAF);
 778                                 return (m);
 779                         } else
 780                                 break;
 781                 } else if (rnode->rn_child[slot] == NULL ||
 782                     vm_radix_keybarr(rnode->rn_child[slot], index))
 783                         break;
 784                 rnode = rnode->rn_child[slot];
 785         }
 786         panic("%s: original replacing page not found", __func__);
 787 }
 788
 789 void
 790 vm_radix_wait(void)
 791 {
 792         uma_zwait(vm_radix_node_zone);
 793 }
 794
 795 #ifdef DDB
 796 /*
 797  * Show details about the given radix node.
 798  */
 799 DB_SHOW_COMMAND(radixnode, db_show_radixnode)
 800 {
 801         struct vm_radix_node *rnode;
 802         int i;
 803
 804         if (!have_addr)
 805                 return;
 806         rnode = (struct vm_radix_node *)addr;
 807         db_printf("radixnode %p, owner %jx, children count %u, level %u:\n",
 808             (void *)rnode, (uintmax_t)rnode->rn_owner, rnode->rn_count,
 809             rnode->rn_clev);
 810         for (i = 0; i < VM_RADIX_COUNT; i++)
 811                 if (rnode->rn_child[i] != NULL)
 812                         db_printf("slot: %d, val: %p, page: %p, clev: %d\n",
 813                             i, (void *)rnode->rn_child[i],
 814                             vm_radix_isleaf(rnode->rn_child[i]) ?
 815                             vm_radix_topage(rnode->rn_child[i]) : NULL,
 816                             rnode->rn_clev);
 817 }
 818 #endif /* DDB */