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 | M_ZERO);
 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 #ifndef UMA_MD_SMALL_ALLOC
 287 /*
 288  * Reserve the KVA necessary to satisfy the node allocation.
 289  * This is mandatory in architectures not supporting direct
 290  * mapping as they will need otherwise to carve into the kernel maps for
 291  * every node allocation, resulting into deadlocks for consumers already
 292  * working with kernel maps.
 293  */
 294 static void
 295 vm_radix_reserve_kva(void *arg __unused)
 296 {
 297
 298         /*
 299          * Calculate the number of reserved nodes, discounting the pages that
 300          * are needed to store them.
 301          */
 302         if (!uma_zone_reserve_kva(vm_radix_node_zone,
 303             ((vm_paddr_t)vm_cnt.v_page_count * PAGE_SIZE) / (PAGE_SIZE +
 304             sizeof(struct vm_radix_node))))
 305                 panic("%s: unable to reserve KVA", __func__);
 306 }
 307 SYSINIT(vm_radix_reserve_kva, SI_SUB_KMEM, SI_ORDER_THIRD,
 308     vm_radix_reserve_kva, NULL);
 309 #endif
 310
 311 /*
 312  * Initialize the UMA slab zone.
 313  */
 314 void
 315 vm_radix_zinit(void)
 316 {
 317
 318         vm_radix_node_zone = uma_zcreate("RADIX NODE",
 319             sizeof(struct vm_radix_node), NULL,
 320 #ifdef INVARIANTS
 321             vm_radix_node_zone_dtor,
 322 #else
 323             NULL,
 324 #endif
 325             NULL, NULL, VM_RADIX_PAD, UMA_ZONE_VM);
 326 }
 327
 328 /*
 329  * Inserts the key-value pair into the trie.
 330  * Panics if the key already exists.
 331  */
 332 int
 333 vm_radix_insert(struct vm_radix *rtree, vm_page_t page)
 334 {
 335         vm_pindex_t index, newind;
 336         void **parentp;
 337         struct vm_radix_node *rnode, *tmp;
 338         vm_page_t m;
 339         int slot;
 340         uint16_t clev;
 341
 342         index = page->pindex;
 343
 344         /*
 345          * The owner of record for root is not really important because it
 346          * will never be used.
 347          */
 348         rnode = vm_radix_getroot(rtree);
 349         if (rnode == NULL) {
 350                 rtree->rt_root = (uintptr_t)page | VM_RADIX_ISLEAF;
 351                 return (0);
 352         }
 353         parentp = (void **)&rtree->rt_root;
 354         for (;;) {
 355                 if (vm_radix_isleaf(rnode)) {
 356                         m = vm_radix_topage(rnode);
 357                         if (m->pindex == index)
 358                                 panic("%s: key %jx is already present",
 359                                     __func__, (uintmax_t)index);
 360                         clev = vm_radix_keydiff(m->pindex, index);
 361                         tmp = vm_radix_node_get(vm_radix_trimkey(index,
 362                             clev + 1), 2, clev);
 363                         if (tmp == NULL)
 364                                 return (ENOMEM);
 365                         *parentp = tmp;
 366                         vm_radix_addpage(tmp, index, clev, page);
 367                         vm_radix_addpage(tmp, m->pindex, clev, m);
 368                         return (0);
 369                 } else if (vm_radix_keybarr(rnode, index))
 370                         break;
 371                 slot = vm_radix_slot(index, rnode->rn_clev);
 372                 if (rnode->rn_child[slot] == NULL) {
 373                         rnode->rn_count++;
 374                         vm_radix_addpage(rnode, index, rnode->rn_clev, page);
 375                         return (0);
 376                 }
 377                 parentp = &rnode->rn_child[slot];
 378                 rnode = rnode->rn_child[slot];
 379         }
 380
 381         /*
 382          * A new node is needed because the right insertion level is reached.
 383          * Setup the new intermediate node and add the 2 children: the
 384          * new object and the older edge.
 385          */
 386         newind = rnode->rn_owner;
 387         clev = vm_radix_keydiff(newind, index);
 388         tmp = vm_radix_node_get(vm_radix_trimkey(index, clev + 1), 2, clev);
 389         if (tmp == NULL)
 390                 return (ENOMEM);
 391         *parentp = tmp;
 392         vm_radix_addpage(tmp, index, clev, page);
 393         slot = vm_radix_slot(newind, clev);
 394         tmp->rn_child[slot] = rnode;
 395         return (0);
 396 }
 397
 398 /*
 399  * Returns TRUE if the specified radix tree contains a single leaf and FALSE
 400  * otherwise.
 401  */
 402 boolean_t
 403 vm_radix_is_singleton(struct vm_radix *rtree)
 404 {
 405         struct vm_radix_node *rnode;
 406
 407         rnode = vm_radix_getroot(rtree);
 408         if (rnode == NULL)
 409                 return (FALSE);
 410         return (vm_radix_isleaf(rnode));
 411 }
 412
 413 /*
 414  * Returns the value stored at the index.  If the index is not present,
 415  * NULL is returned.
 416  */
 417 vm_page_t
 418 vm_radix_lookup(struct vm_radix *rtree, vm_pindex_t index)
 419 {
 420         struct vm_radix_node *rnode;
 421         vm_page_t m;
 422         int slot;
 423
 424         rnode = vm_radix_getroot(rtree);
 425         while (rnode != NULL) {
 426                 if (vm_radix_isleaf(rnode)) {
 427                         m = vm_radix_topage(rnode);
 428                         if (m->pindex == index)
 429                                 return (m);
 430                         else
 431                                 break;
 432                 } else if (vm_radix_keybarr(rnode, index))
 433                         break;
 434                 slot = vm_radix_slot(index, rnode->rn_clev);
 435                 rnode = rnode->rn_child[slot];
 436         }
 437         return (NULL);
 438 }
 439
 440 /*
 441  * Look up the nearest entry at a position bigger than or equal to index.
 442  */
 443 vm_page_t
 444 vm_radix_lookup_ge(struct vm_radix *rtree, vm_pindex_t index)
 445 {
 446         struct vm_radix_node *stack[VM_RADIX_LIMIT];
 447         vm_pindex_t inc;
 448         vm_page_t m;
 449         struct vm_radix_node *child, *rnode;
 450 #ifdef INVARIANTS
 451         int loops = 0;
 452 #endif
 453         int slot, tos;
 454
 455         rnode = vm_radix_getroot(rtree);
 456         if (rnode == NULL)
 457                 return (NULL);
 458         else if (vm_radix_isleaf(rnode)) {
 459                 m = vm_radix_topage(rnode);
 460                 if (m->pindex >= index)
 461                         return (m);
 462                 else
 463                         return (NULL);
 464         }
 465         tos = 0;
 466         for (;;) {
 467                 /*
 468                  * If the keys differ before the current bisection node,
 469                  * then the search key might rollback to the earliest
 470                  * available bisection node or to the smallest key
 471                  * in the current node (if the owner is bigger than the
 472                  * search key).
 473                  */
 474                 if (vm_radix_keybarr(rnode, index)) {
 475                         if (index > rnode->rn_owner) {
 476 ascend:
 477                                 KASSERT(++loops < 1000,
 478                                     ("vm_radix_lookup_ge: too many loops"));
 479
 480                                 /*
 481                                  * Pop nodes from the stack until either the
 482                                  * stack is empty or a node that could have a
 483                                  * matching descendant is found.
 484                                  */
 485                                 do {
 486                                         if (tos == 0)
 487                                                 return (NULL);
 488                                         rnode = stack[--tos];
 489                                 } while (vm_radix_slot(index,
 490                                     rnode->rn_clev) == (VM_RADIX_COUNT - 1));
 491
 492                                 /*
 493                                  * The following computation cannot overflow
 494                                  * because index's slot at the current level
 495                                  * is less than VM_RADIX_COUNT - 1.
 496                                  */
 497                                 index = vm_radix_trimkey(index,
 498                                     rnode->rn_clev);
 499                                 index += VM_RADIX_UNITLEVEL(rnode->rn_clev);
 500                         } else
 501                                 index = rnode->rn_owner;
 502                         KASSERT(!vm_radix_keybarr(rnode, index),
 503                             ("vm_radix_lookup_ge: keybarr failed"));
 504                 }
 505                 slot = vm_radix_slot(index, rnode->rn_clev);
 506                 child = rnode->rn_child[slot];
 507                 if (vm_radix_isleaf(child)) {
 508                         m = vm_radix_topage(child);
 509                         if (m->pindex >= index)
 510                                 return (m);
 511                 } else if (child != NULL)
 512                         goto descend;
 513
 514                 /*
 515                  * Look for an available edge or page within the current
 516                  * bisection node.
 517                  */
 518                 if (slot < (VM_RADIX_COUNT - 1)) {
 519                         inc = VM_RADIX_UNITLEVEL(rnode->rn_clev);
 520                         index = vm_radix_trimkey(index, rnode->rn_clev);
 521                         do {
 522                                 index += inc;
 523                                 slot++;
 524                                 child = rnode->rn_child[slot];
 525                                 if (vm_radix_isleaf(child)) {
 526                                         m = vm_radix_topage(child);
 527                                         if (m->pindex >= index)
 528                                                 return (m);
 529                                 } else if (child != NULL)
 530                                         goto descend;
 531                         } while (slot < (VM_RADIX_COUNT - 1));
 532                 }
 533                 KASSERT(child == NULL || vm_radix_isleaf(child),
 534                     ("vm_radix_lookup_ge: child is radix node"));
 535
 536                 /*
 537                  * If a page or edge bigger than the search slot is not found
 538                  * in the current node, ascend to the next higher-level node.
 539                  */
 540                 goto ascend;
 541 descend:
 542                 KASSERT(rnode->rn_clev > 0,
 543                     ("vm_radix_lookup_ge: pushing leaf's parent"));
 544                 KASSERT(tos < VM_RADIX_LIMIT,
 545                     ("vm_radix_lookup_ge: stack overflow"));
 546                 stack[tos++] = rnode;
 547                 rnode = child;
 548         }
 549 }
 550
 551 /*
 552  * Look up the nearest entry at a position less than or equal to index.
 553  */
 554 vm_page_t
 555 vm_radix_lookup_le(struct vm_radix *rtree, vm_pindex_t index)
 556 {
 557         struct vm_radix_node *stack[VM_RADIX_LIMIT];
 558         vm_pindex_t inc;
 559         vm_page_t m;
 560         struct vm_radix_node *child, *rnode;
 561 #ifdef INVARIANTS
 562         int loops = 0;
 563 #endif
 564         int slot, tos;
 565
 566         rnode = vm_radix_getroot(rtree);
 567         if (rnode == NULL)
 568                 return (NULL);
 569         else if (vm_radix_isleaf(rnode)) {
 570                 m = vm_radix_topage(rnode);
 571                 if (m->pindex <= index)
 572                         return (m);
 573                 else
 574                         return (NULL);
 575         }
 576         tos = 0;
 577         for (;;) {
 578                 /*
 579                  * If the keys differ before the current bisection node,
 580                  * then the search key might rollback to the earliest
 581                  * available bisection node or to the largest key
 582                  * in the current node (if the owner is smaller than the
 583                  * search key).
 584                  */
 585                 if (vm_radix_keybarr(rnode, index)) {
 586                         if (index > rnode->rn_owner) {
 587                                 index = rnode->rn_owner + VM_RADIX_COUNT *
 588                                     VM_RADIX_UNITLEVEL(rnode->rn_clev);
 589                         } else {
 590 ascend:
 591                                 KASSERT(++loops < 1000,
 592                                     ("vm_radix_lookup_le: too many loops"));
 593
 594                                 /*
 595                                  * Pop nodes from the stack until either the
 596                                  * stack is empty or a node that could have a
 597                                  * matching descendant is found.
 598                                  */
 599                                 do {
 600                                         if (tos == 0)
 601                                                 return (NULL);
 602                                         rnode = stack[--tos];
 603                                 } while (vm_radix_slot(index,
 604                                     rnode->rn_clev) == 0);
 605
 606                                 /*
 607                                  * The following computation cannot overflow
 608                                  * because index's slot at the current level
 609                                  * is greater than 0.
 610                                  */
 611                                 index = vm_radix_trimkey(index,
 612                                     rnode->rn_clev);
 613                         }
 614                         index--;
 615                         KASSERT(!vm_radix_keybarr(rnode, index),
 616                             ("vm_radix_lookup_le: keybarr failed"));
 617                 }
 618                 slot = vm_radix_slot(index, rnode->rn_clev);
 619                 child = rnode->rn_child[slot];
 620                 if (vm_radix_isleaf(child)) {
 621                         m = vm_radix_topage(child);
 622                         if (m->pindex <= index)
 623                                 return (m);
 624                 } else if (child != NULL)
 625                         goto descend;
 626
 627                 /*
 628                  * Look for an available edge or page within the current
 629                  * bisection node.
 630                  */
 631                 if (slot > 0) {
 632                         inc = VM_RADIX_UNITLEVEL(rnode->rn_clev);
 633                         index |= inc - 1;
 634                         do {
 635                                 index -= inc;
 636                                 slot--;
 637                                 child = rnode->rn_child[slot];
 638                                 if (vm_radix_isleaf(child)) {
 639                                         m = vm_radix_topage(child);
 640                                         if (m->pindex <= index)
 641                                                 return (m);
 642                                 } else if (child != NULL)
 643                                         goto descend;
 644                         } while (slot > 0);
 645                 }
 646                 KASSERT(child == NULL || vm_radix_isleaf(child),
 647                     ("vm_radix_lookup_le: child is radix node"));
 648
 649                 /*
 650                  * If a page or edge smaller than the search slot is not found
 651                  * in the current node, ascend to the next higher-level node.
 652                  */
 653                 goto ascend;
 654 descend:
 655                 KASSERT(rnode->rn_clev > 0,
 656                     ("vm_radix_lookup_le: pushing leaf's parent"));
 657                 KASSERT(tos < VM_RADIX_LIMIT,
 658                     ("vm_radix_lookup_le: stack overflow"));
 659                 stack[tos++] = rnode;
 660                 rnode = child;
 661         }
 662 }
 663
 664 /*
 665  * Remove the specified index from the trie, and return the value stored at
 666  * that index.  If the index is not present, return NULL.
 667  */
 668 vm_page_t
 669 vm_radix_remove(struct vm_radix *rtree, vm_pindex_t index)
 670 {
 671         struct vm_radix_node *rnode, *parent;
 672         vm_page_t m;
 673         int i, slot;
 674
 675         rnode = vm_radix_getroot(rtree);
 676         if (vm_radix_isleaf(rnode)) {
 677                 m = vm_radix_topage(rnode);
 678                 if (m->pindex != index)
 679                         return (NULL);
 680                 vm_radix_setroot(rtree, NULL);
 681                 return (m);
 682         }
 683         parent = NULL;
 684         for (;;) {
 685                 if (rnode == NULL)
 686                         return (NULL);
 687                 slot = vm_radix_slot(index, rnode->rn_clev);
 688                 if (vm_radix_isleaf(rnode->rn_child[slot])) {
 689                         m = vm_radix_topage(rnode->rn_child[slot]);
 690                         if (m->pindex != index)
 691                                 return (NULL);
 692                         rnode->rn_child[slot] = NULL;
 693                         rnode->rn_count--;
 694                         if (rnode->rn_count > 1)
 695                                 return (m);
 696                         for (i = 0; i < VM_RADIX_COUNT; i++)
 697                                 if (rnode->rn_child[i] != NULL)
 698                                         break;
 699                         KASSERT(i != VM_RADIX_COUNT,
 700                             ("%s: invalid node configuration", __func__));
 701                         if (parent == NULL)
 702                                 vm_radix_setroot(rtree, rnode->rn_child[i]);
 703                         else {
 704                                 slot = vm_radix_slot(index, parent->rn_clev);
 705                                 KASSERT(parent->rn_child[slot] == rnode,
 706                                     ("%s: invalid child value", __func__));
 707                                 parent->rn_child[slot] = rnode->rn_child[i];
 708                         }
 709                         rnode->rn_count--;
 710                         rnode->rn_child[i] = NULL;
 711                         vm_radix_node_put(rnode);
 712                         return (m);
 713                 }
 714                 parent = rnode;
 715                 rnode = rnode->rn_child[slot];
 716         }
 717 }
 718
 719 /*
 720  * Remove and free all the nodes from the radix tree.
 721  * This function is recursive but there is a tight control on it as the
 722  * maximum depth of the tree is fixed.
 723  */
 724 void
 725 vm_radix_reclaim_allnodes(struct vm_radix *rtree)
 726 {
 727         struct vm_radix_node *root;
 728
 729         root = vm_radix_getroot(rtree);
 730         if (root == NULL)
 731                 return;
 732         vm_radix_setroot(rtree, NULL);
 733         if (!vm_radix_isleaf(root))
 734                 vm_radix_reclaim_allnodes_int(root);
 735 }
 736
 737 /*
 738  * Replace an existing page in the trie with another one.
 739  * Panics if there is not an old page in the trie at the new page's index.
 740  */
 741 vm_page_t
 742 vm_radix_replace(struct vm_radix *rtree, vm_page_t newpage)
 743 {
 744         struct vm_radix_node *rnode;
 745         vm_page_t m;
 746         vm_pindex_t index;
 747         int slot;
 748
 749         index = newpage->pindex;
 750         rnode = vm_radix_getroot(rtree);
 751         if (rnode == NULL)
 752                 panic("%s: replacing page on an empty trie", __func__);
 753         if (vm_radix_isleaf(rnode)) {
 754                 m = vm_radix_topage(rnode);
 755                 if (m->pindex != index)
 756                         panic("%s: original replacing root key not found",
 757                             __func__);
 758                 rtree->rt_root = (uintptr_t)newpage | VM_RADIX_ISLEAF;
 759                 return (m);
 760         }
 761         for (;;) {
 762                 slot = vm_radix_slot(index, rnode->rn_clev);
 763                 if (vm_radix_isleaf(rnode->rn_child[slot])) {
 764                         m = vm_radix_topage(rnode->rn_child[slot]);
 765                         if (m->pindex == index) {
 766                                 rnode->rn_child[slot] =
 767                                     (void *)((uintptr_t)newpage |
 768                                     VM_RADIX_ISLEAF);
 769                                 return (m);
 770                         } else
 771                                 break;
 772                 } else if (rnode->rn_child[slot] == NULL ||
 773                     vm_radix_keybarr(rnode->rn_child[slot], index))
 774                         break;
 775                 rnode = rnode->rn_child[slot];
 776         }
 777         panic("%s: original replacing page not found", __func__);
 778 }
 779
 780 void
 781 vm_radix_wait(void)
 782 {
 783         uma_zwait(vm_radix_node_zone);
 784 }
 785
 786 #ifdef DDB
 787 /*
 788  * Show details about the given radix node.
 789  */
 790 DB_SHOW_COMMAND(radixnode, db_show_radixnode)
 791 {
 792         struct vm_radix_node *rnode;
 793         int i;
 794
 795         if (!have_addr)
 796                 return;
 797         rnode = (struct vm_radix_node *)addr;
 798         db_printf("radixnode %p, owner %jx, children count %u, level %u:\n",
 799             (void *)rnode, (uintmax_t)rnode->rn_owner, rnode->rn_count,
 800             rnode->rn_clev);
 801         for (i = 0; i < VM_RADIX_COUNT; i++)
 802                 if (rnode->rn_child[i] != NULL)
 803                         db_printf("slot: %d, val: %p, page: %p, clev: %d\n",
 804                             i, (void *)rnode->rn_child[i],
 805                             vm_radix_isleaf(rnode->rn_child[i]) ?
 806                             vm_radix_topage(rnode->rn_child[i]) : NULL,
 807                             rnode->rn_clev);
 808 }
 809 #endif /* DDB */