git.ozlabs.org Git - ccan/blob - ccan/alloc/alloc.c

   1 #include <unistd.h>
   2 #include <stdint.h>
   3 #include <string.h>
   4 #include <limits.h>
   5 #include <assert.h>
   6 #include <stdlib.h>
   7 #include "alloc.h"
   8 #include "bitops.h"
   9 #include "tiny.h"
  10 #include <ccan/build_assert/build_assert.h>
  11 #include <ccan/likely/likely.h>
  12 #include <ccan/alignof/alignof.h>
  13 #include <ccan/short_types/short_types.h>
  14 #include <ccan/compiler/compiler.h>
  15 #include "config.h"
  16
  17 /*
  18    Inspired by (and parts taken from) Andrew Tridgell's alloc_mmap:
  19    http://samba.org/~tridge/junkcode/alloc_mmap/
  20
  21    Copyright (C) Andrew Tridgell 2007
  22
  23    This library is free software; you can redistribute it and/or
  24    modify it under the terms of the GNU Lesser General Public
  25    License as published by the Free Software Foundation; either
  26    version 2 of the License, or (at your option) any later version.
  27
  28    This library is distributed in the hope that it will be useful,
  29    but WITHOUT ANY WARRANTY; without even the implied warranty of
  30    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  31    Lesser General Public License for more details.
  32
  33    You should have received a copy of the GNU Lesser General Public
  34    License along with this library; if not, write to the Free Software
  35    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  36  */
  37
  38 /* We divide the pool into this many large pages (nearest power of 2) */
  39 #define MAX_LARGE_PAGES (256UL)
  40
  41 /* 32 small pages == 1 large page. */
  42 #define BITS_FROM_SMALL_TO_LARGE_PAGE 5
  43
  44 #define MAX_SMALL_PAGES (MAX_LARGE_PAGES << BITS_FROM_SMALL_TO_LARGE_PAGE)
  45
  46 /* Smallest pool size for this scheme: 128-byte small pages.  That's
  47  * 9/13% overhead for 32/64 bit. */
  48 #define MIN_USEFUL_SIZE (MAX_SMALL_PAGES * 128)
  49
  50 /* Every 4 buckets, we jump up a power of 2. ...8 10 12 14 16 20 24 28 32... */
  51 #define INTER_BUCKET_SPACE 4
  52
  53 #define SMALL_PAGES_PER_LARGE_PAGE (1 << BITS_FROM_SMALL_TO_LARGE_PAGE)
  54
  55 /* FIXME: Figure this out properly. */
  56 #define MAX_SIZE (1 << 30)
  57
  58 /* How few object to fit in a page before using a larger one? (8) */
  59 #define MAX_PAGE_OBJECT_ORDER   3
  60
  61 #define BITS_PER_LONG (sizeof(long) * CHAR_BIT)
  62
  63 struct bucket_state {
  64         u32 elements_per_page;
  65         u16 page_list;
  66         u16 full_list;
  67 };
  68
  69 struct header {
  70         /* Bitmap of which pages are large. */
  71         unsigned long pagesize[MAX_LARGE_PAGES / BITS_PER_LONG];
  72
  73         /* List of unused small/large pages. */
  74         u16 small_free_list;
  75         u16 large_free_list;
  76
  77         /* List of huge allocs. */
  78         unsigned long huge;
  79
  80         /* This is less defined: we have two buckets for each power of 2 */
  81         struct bucket_state bs[1];
  82 };
  83
  84 struct huge_alloc {
  85         unsigned long next, prev;
  86         unsigned long off, len;
  87 };
  88
  89 struct page_header {
  90         u16 next, prev;
  91         /* FIXME: We can just count all-0 and all-1 used[] elements. */
  92         unsigned elements_used : 25;
  93         unsigned bucket : 7;
  94         unsigned long used[1]; /* One bit per element. */
  95 };
  96
  97 /*
  98  * Every 4 buckets, the size doubles.
  99  * Between buckets, sizes increase linearly.
 100  *
 101  * eg. bucket 40 = 2^10                 = 1024
 102  *     bucket 41 = 2^10 + 2^10*4        = 1024 + 256
 103  *     bucket 42 = 2^10 + 2^10*4        = 1024 + 512
 104  *     bucket 43 = 2^10 + 2^10*4        = 1024 + 768
 105  *     bucket 45 = 2^11                 = 2048
 106  *
 107  * Care is taken to handle low numbered buckets, at cost of overflow.
 108  */
 109 static unsigned long bucket_to_size(unsigned int bucket)
 110 {
 111         unsigned long base = 1UL << (bucket / INTER_BUCKET_SPACE);
 112         return base + ((bucket % INTER_BUCKET_SPACE)
 113                        << (bucket / INTER_BUCKET_SPACE))
 114                 / INTER_BUCKET_SPACE;
 115 }
 116
 117 /*
 118  * Say size is 10.
 119  *   fls(size/2) == 3.  1 << 3 == 8, so we're 2 too large, out of a possible
 120  * 8 too large.  That's 1/4 of the way to the next power of 2 == 1 bucket.
 121  *
 122  * We make sure we round up.  Note that this fails on 32 bit at size
 123  * 1879048193 (around bucket 120).
 124  */
 125 static unsigned int size_to_bucket(unsigned long size)
 126 {
 127         unsigned int base = fls(size/2);
 128         unsigned long overshoot;
 129
 130         overshoot = size - (1UL << base);
 131         return base * INTER_BUCKET_SPACE
 132                 + ((overshoot * INTER_BUCKET_SPACE + (1UL << base)-1) >> base);
 133 }
 134
 135 static unsigned int small_page_bits(unsigned long poolsize)
 136 {
 137         return fls(poolsize / MAX_SMALL_PAGES - 1);
 138 }
 139
 140 static struct page_header *from_pgnum(struct header *head,
 141                                       unsigned long pgnum,
 142                                       unsigned sp_bits)
 143 {
 144         return (struct page_header *)((char *)head + (pgnum << sp_bits));
 145 }
 146
 147 static u16 to_pgnum(struct header *head, void *p, unsigned sp_bits)
 148 {
 149         return ((char *)p - (char *)head) >> sp_bits;
 150 }
 151
 152 static size_t used_size(unsigned int num_elements)
 153 {
 154         return align_up(num_elements, BITS_PER_LONG) / CHAR_BIT;
 155 }
 156
 157 /*
 158  * We always align the first entry to the lower power of 2.
 159  * eg. the 12-byte bucket gets 8-byte aligned.  The 4096-byte bucket
 160  * gets 4096-byte aligned.
 161  */
 162 static unsigned long page_header_size(unsigned int align_bits,
 163                                       unsigned long num_elements)
 164 {
 165         unsigned long size;
 166
 167         size = sizeof(struct page_header)
 168                 - sizeof(((struct page_header *)0)->used)
 169                 + used_size(num_elements);
 170         return align_up(size, 1UL << align_bits);
 171 }
 172
 173 static void add_to_list(struct header *head,
 174                         u16 *list, struct page_header *ph, unsigned sp_bits)
 175 {
 176         unsigned long h = *list, offset = to_pgnum(head, ph, sp_bits);
 177
 178         ph->next = h;
 179         if (h) {
 180                 struct page_header *prev = from_pgnum(head, h, sp_bits);
 181                 assert(prev->prev == 0);
 182                 prev->prev = offset;
 183         }
 184         *list = offset;
 185         ph->prev = 0;
 186 }
 187
 188 static void del_from_list(struct header *head,
 189                           u16 *list, struct page_header *ph, unsigned sp_bits)
 190 {
 191         /* Front of list? */
 192         if (ph->prev == 0) {
 193                 *list = ph->next;
 194         } else {
 195                 struct page_header *prev = from_pgnum(head, ph->prev, sp_bits);
 196                 prev->next = ph->next;
 197         }
 198         if (ph->next != 0) {
 199                 struct page_header *next = from_pgnum(head, ph->next, sp_bits);
 200                 next->prev = ph->prev;
 201         }
 202 }
 203
 204 static u16 pop_from_list(struct header *head,
 205                                    u16 *list,
 206                                    unsigned int sp_bits)
 207 {
 208         u16 h = *list;
 209         struct page_header *ph = from_pgnum(head, h, sp_bits);
 210
 211         if (likely(h)) {
 212                 *list = ph->next;
 213                 if (*list)
 214                         from_pgnum(head, *list, sp_bits)->prev = 0;
 215         }
 216         return h;
 217 }
 218
 219 static void add_to_huge_list(struct header *head, struct huge_alloc *ha)
 220 {
 221         unsigned long h = head->huge;
 222         unsigned long offset = (char *)ha - (char *)head;
 223
 224         ha->next = h;
 225         if (h) {
 226                 struct huge_alloc *prev = (void *)((char *)head + h);
 227                 assert(prev->prev == 0);
 228                 prev->prev = offset;
 229         }
 230         head->huge = offset;
 231         ha->prev = 0;
 232 }
 233
 234 static void del_from_huge(struct header *head, struct huge_alloc *ha)
 235 {
 236         /* Front of list? */
 237         if (ha->prev == 0) {
 238                 head->huge = ha->next;
 239         } else {
 240                 struct huge_alloc *prev = (void *)((char *)head + ha->prev);
 241                 prev->next = ha->next;
 242         }
 243         if (ha->next != 0) {
 244                 struct huge_alloc *next = (void *)((char *)head + ha->next);
 245                 next->prev = ha->prev;
 246         }
 247 }
 248
 249 static void add_small_page_to_freelist(struct header *head,
 250                                        struct page_header *ph,
 251                                        unsigned int sp_bits)
 252 {
 253         add_to_list(head, &head->small_free_list, ph, sp_bits);
 254 }
 255
 256 static void add_large_page_to_freelist(struct header *head,
 257                                        struct page_header *ph,
 258                                        unsigned int sp_bits)
 259 {
 260         add_to_list(head, &head->large_free_list, ph, sp_bits);
 261 }
 262
 263 static void add_to_bucket_list(struct header *head,
 264                                struct bucket_state *bs,
 265                                struct page_header *ph,
 266                                unsigned int sp_bits)
 267 {
 268         add_to_list(head, &bs->page_list, ph, sp_bits);
 269 }
 270
 271 static void del_from_bucket_list(struct header *head,
 272                                  struct bucket_state *bs,
 273                                  struct page_header *ph,
 274                                  unsigned int sp_bits)
 275 {
 276         del_from_list(head, &bs->page_list, ph, sp_bits);
 277 }
 278
 279 static void del_from_bucket_full_list(struct header *head,
 280                                       struct bucket_state *bs,
 281                                       struct page_header *ph,
 282                                       unsigned int sp_bits)
 283 {
 284         del_from_list(head, &bs->full_list, ph, sp_bits);
 285 }
 286
 287 static void add_to_bucket_full_list(struct header *head,
 288                                     struct bucket_state *bs,
 289                                     struct page_header *ph,
 290                                     unsigned int sp_bits)
 291 {
 292         add_to_list(head, &bs->full_list, ph, sp_bits);
 293 }
 294
 295 static void clear_bit(unsigned long bitmap[], unsigned int off)
 296 {
 297         bitmap[off / BITS_PER_LONG] &= ~(1UL << (off % BITS_PER_LONG));
 298 }
 299
 300 static bool test_bit(const unsigned long bitmap[], unsigned int off)
 301 {
 302         return bitmap[off / BITS_PER_LONG] & (1UL << (off % BITS_PER_LONG));
 303 }
 304
 305 static void set_bit(unsigned long bitmap[], unsigned int off)
 306 {
 307         bitmap[off / BITS_PER_LONG] |= (1UL << (off % BITS_PER_LONG));
 308 }
 309
 310 /* There must be a bit to be found. */
 311 static unsigned int find_free_bit(const unsigned long bitmap[])
 312 {
 313         unsigned int i;
 314
 315         for (i = 0; bitmap[i] == -1UL; i++);
 316         return (i*BITS_PER_LONG) + ffsl(~bitmap[i]) - 1;
 317 }
 318
 319 /* How many elements can we fit in a page? */
 320 static unsigned long elements_per_page(unsigned long align_bits,
 321                                        unsigned long esize,
 322                                        unsigned long psize)
 323 {
 324         unsigned long num, overhead;
 325
 326         /* First approximation: no extra room for bitmap. */
 327         overhead = align_up(sizeof(struct page_header), 1UL << align_bits);
 328         num = (psize - overhead) / esize;
 329
 330         while (page_header_size(align_bits, num) + esize * num > psize)
 331                 num--;
 332         return num;
 333 }
 334
 335 static bool large_page_bucket(unsigned int bucket, unsigned int sp_bits)
 336 {
 337         unsigned long max_smallsize;
 338
 339         /* Note: this doesn't take into account page header. */
 340         max_smallsize = (1UL << sp_bits) >> MAX_PAGE_OBJECT_ORDER;
 341
 342         return bucket_to_size(bucket) > max_smallsize;
 343 }
 344
 345 static unsigned int max_bucket(unsigned int lp_bits)
 346 {
 347         return (lp_bits - MAX_PAGE_OBJECT_ORDER) * INTER_BUCKET_SPACE;
 348 }
 349
 350 void alloc_init(void *pool, unsigned long poolsize)
 351 {
 352         struct header *head = pool;
 353         struct page_header *ph;
 354         unsigned int lp_bits, sp_bits, num_buckets;
 355         unsigned long header_size, i;
 356
 357         if (poolsize < MIN_USEFUL_SIZE) {
 358                 tiny_alloc_init(pool, poolsize);
 359                 return;
 360         }
 361
 362         /* We rely on page numbers fitting in 16 bit. */
 363         BUILD_ASSERT(MAX_SMALL_PAGES < 65536);
 364
 365         sp_bits = small_page_bits(poolsize);
 366         lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
 367
 368         num_buckets = max_bucket(lp_bits);
 369
 370         head = pool;
 371         header_size = sizeof(*head) + sizeof(head->bs) * (num_buckets-1);
 372
 373         memset(head, 0, header_size);
 374         for (i = 0; i < num_buckets; i++) {
 375                 unsigned long pagesize;
 376
 377                 if (large_page_bucket(i, sp_bits))
 378                         pagesize = 1UL << lp_bits;
 379                 else
 380                         pagesize = 1UL << sp_bits;
 381
 382                 head->bs[i].elements_per_page
 383                         = elements_per_page(i / INTER_BUCKET_SPACE,
 384                                             bucket_to_size(i),
 385                                             pagesize);
 386         }
 387
 388         /* They start as all large pages. */
 389         memset(head->pagesize, 0xFF, sizeof(head->pagesize));
 390         /* FIXME: small pages for last bit? */
 391
 392         /* Split first page into small pages. */
 393         assert(header_size < (1UL << lp_bits));
 394         clear_bit(head->pagesize, 0);
 395
 396         /* Skip over page(s) used by header, add rest to free list */
 397         for (i = align_up(header_size, (1UL << sp_bits)) >> sp_bits;
 398              i < SMALL_PAGES_PER_LARGE_PAGE;
 399              i++) {
 400                 ph = from_pgnum(head, i, sp_bits);
 401                 ph->elements_used = 0;
 402                 add_small_page_to_freelist(head, ph, sp_bits);
 403         }
 404
 405         /* Add the rest of the pages as large pages. */
 406         i = SMALL_PAGES_PER_LARGE_PAGE;
 407         while ((i << sp_bits) + (1UL << lp_bits) <= poolsize) {
 408                 assert(i < MAX_SMALL_PAGES);
 409                 ph = from_pgnum(head, i, sp_bits);
 410                 ph->elements_used = 0;
 411                 add_large_page_to_freelist(head, ph, sp_bits);
 412                 i += SMALL_PAGES_PER_LARGE_PAGE;
 413         }
 414 }
 415
 416 /* A large page worth of small pages are free: delete them from free list. */
 417 static void del_large_from_small_free_list(struct header *head,
 418                                            struct page_header *ph,
 419                                            unsigned int sp_bits)
 420 {
 421         unsigned long i;
 422
 423         for (i = 0; i < SMALL_PAGES_PER_LARGE_PAGE; i++) {
 424                 del_from_list(head, &head->small_free_list,
 425                               (void *)ph + (i << sp_bits),
 426                               sp_bits);
 427         }
 428 }
 429
 430 static bool all_empty(struct header *head,
 431                       unsigned long pgnum,
 432                       unsigned sp_bits)
 433 {
 434         unsigned long i;
 435
 436         for (i = 0; i < SMALL_PAGES_PER_LARGE_PAGE; i++) {
 437                 struct page_header *ph = from_pgnum(head, pgnum + i, sp_bits);
 438                 if (ph->elements_used)
 439                         return false;
 440         }
 441         return true;
 442 }
 443
 444 static void recombine_small_pages(struct header *head, unsigned long poolsize,
 445                                   unsigned int sp_bits)
 446 {
 447         unsigned long i;
 448         unsigned int lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
 449
 450         /* Look for small pages to coalesce, after first large page. */
 451         for (i = SMALL_PAGES_PER_LARGE_PAGE;
 452              i < (poolsize >> lp_bits) << BITS_FROM_SMALL_TO_LARGE_PAGE;
 453              i += SMALL_PAGES_PER_LARGE_PAGE) {
 454                 /* Already a large page? */
 455                 if (test_bit(head->pagesize, i / SMALL_PAGES_PER_LARGE_PAGE))
 456                         continue;
 457                 if (all_empty(head, i, sp_bits)) {
 458                         struct page_header *ph = from_pgnum(head, i, sp_bits);
 459                         set_bit(head->pagesize,
 460                                 i / SMALL_PAGES_PER_LARGE_PAGE);
 461                         del_large_from_small_free_list(head, ph, sp_bits);
 462                         add_large_page_to_freelist(head, ph, sp_bits);
 463                 }
 464         }
 465 }
 466
 467 static u16 get_large_page(struct header *head, unsigned long poolsize,
 468                           unsigned int sp_bits)
 469 {
 470         unsigned int lp_bits, page;
 471
 472         lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
 473
 474         page = pop_from_list(head, &head->large_free_list, sp_bits);
 475         if (likely(page))
 476                 return page;
 477
 478         recombine_small_pages(head, poolsize, sp_bits);
 479
 480         return pop_from_list(head, &head->large_free_list, sp_bits);
 481 }
 482
 483 /* Returns small page. */
 484 static unsigned long break_up_large_page(struct header *head,
 485                                          unsigned int sp_bits,
 486                                          u16 lpage)
 487 {
 488         unsigned int i;
 489
 490         clear_bit(head->pagesize, lpage >> BITS_FROM_SMALL_TO_LARGE_PAGE);
 491
 492         for (i = 1; i < SMALL_PAGES_PER_LARGE_PAGE; i++) {
 493                 struct page_header *ph = from_pgnum(head, lpage + i, sp_bits);
 494                 /* Initialize this: huge_alloc reads it. */
 495                 ph->elements_used = 0;
 496                 add_small_page_to_freelist(head, ph, sp_bits);
 497         }
 498
 499         return lpage;
 500 }
 501
 502 static u16 get_small_page(struct header *head, unsigned long poolsize,
 503                           unsigned int sp_bits)
 504 {
 505         u16 ret;
 506
 507         ret = pop_from_list(head, &head->small_free_list, sp_bits);
 508         if (likely(ret))
 509                 return ret;
 510         ret = get_large_page(head, poolsize, sp_bits);
 511         if (likely(ret))
 512                 ret = break_up_large_page(head, sp_bits, ret);
 513         return ret;
 514 }
 515
 516 static bool huge_allocated(struct header *head, unsigned long offset)
 517 {
 518         unsigned long i;
 519         struct huge_alloc *ha;
 520
 521         for (i = head->huge; i; i = ha->next) {
 522                 ha = (void *)((char *)head + i);
 523                 if (ha->off <= offset && ha->off + ha->len > offset)
 524                         return true;
 525         }
 526         return false;
 527 }
 528
 529 /* They want something really big.  Aim for contiguous pages (slow). */
 530 static COLD void *huge_alloc(void *pool, unsigned long poolsize,
 531                              unsigned long size, unsigned long align)
 532 {
 533         struct header *head = pool;
 534         struct huge_alloc *ha;
 535         unsigned long i, sp_bits, lp_bits, num, header_size;
 536
 537         sp_bits = small_page_bits(poolsize);
 538         lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
 539
 540         /* Allocate tracking structure optimistically. */
 541         ha = alloc_get(pool, poolsize, sizeof(*ha), ALIGNOF(*ha));
 542         if (!ha)
 543                 return NULL;
 544
 545         /* First search for contiguous small pages... */
 546         header_size = sizeof(*head) + sizeof(head->bs) * (max_bucket(lp_bits)-1);
 547
 548         num = 0;
 549         for (i = (header_size + (1UL << sp_bits) - 1) >> sp_bits;
 550              i << sp_bits < poolsize;
 551              i++) {
 552                 struct page_header *pg;
 553                 unsigned long off = (i << sp_bits);
 554
 555                 /* Skip over large pages. */
 556                 if (test_bit(head->pagesize, i >> BITS_FROM_SMALL_TO_LARGE_PAGE)) {
 557                         i += (1UL << BITS_FROM_SMALL_TO_LARGE_PAGE)-1;
 558                         continue;
 559                 }
 560
 561                 /* Does this page meet alignment requirements? */
 562                 if (!num && off % align != 0)
 563                         continue;
 564
 565                 /* FIXME: This makes us O(n^2). */
 566                 if (huge_allocated(head, off)) {
 567                         num = 0;
 568                         continue;
 569                 }
 570
 571                 pg = (struct page_header *)((char *)head + off);
 572                 if (pg->elements_used) {
 573                         num = 0;
 574                         continue;
 575                 }
 576
 577                 num++;
 578                 if (num << sp_bits >= size) {
 579                         unsigned long pgnum;
 580
 581                         /* Remove from free list. */
 582                         for (pgnum = i; pgnum > i - num; pgnum--) {
 583                                 pg = from_pgnum(head, pgnum, sp_bits);
 584                                 del_from_list(head,
 585                                               &head->small_free_list,
 586                                               pg, sp_bits);
 587                         }
 588                         ha->off = (i - num + 1) << sp_bits;
 589                         ha->len = num << sp_bits;
 590                         goto done;
 591                 }
 592         }
 593
 594         /* Now search for large pages... */
 595         recombine_small_pages(head, poolsize, sp_bits);
 596
 597         num = 0;
 598         for (i = (header_size + (1UL << lp_bits) - 1) >> lp_bits;
 599              (i << lp_bits) < poolsize; i++) {
 600                 struct page_header *pg;
 601                 unsigned long off = (i << lp_bits);
 602
 603                 /* Ignore small pages. */
 604                 if (!test_bit(head->pagesize, i))
 605                         continue;
 606
 607                 /* Does this page meet alignment requirements? */
 608                 if (!num && off % align != 0)
 609                         continue;
 610
 611                 /* FIXME: This makes us O(n^2). */
 612                 if (huge_allocated(head, off)) {
 613                         num = 0;
 614                         continue;
 615                 }
 616
 617                 pg = (struct page_header *)((char *)head + off);
 618                 if (pg->elements_used) {
 619                         num = 0;
 620                         continue;
 621                 }
 622
 623                 num++;
 624                 if (num << lp_bits >= size) {
 625                         unsigned long pgnum;
 626
 627                         /* Remove from free list. */
 628                         for (pgnum = i; pgnum > i - num; pgnum--) {
 629                                 pg = from_pgnum(head, pgnum, lp_bits);
 630                                 del_from_list(head,
 631                                               &head->large_free_list,
 632                                               pg, sp_bits);
 633                         }
 634                         ha->off = (i - num + 1) << lp_bits;
 635                         ha->len = num << lp_bits;
 636                         goto done;
 637                 }
 638         }
 639
 640         /* Unable to satisfy: free huge alloc structure. */
 641         alloc_free(pool, poolsize, ha);
 642         return NULL;
 643
 644 done:
 645         add_to_huge_list(pool, ha);
 646         return (char *)pool + ha->off;
 647 }
 648
 649 static COLD void
 650 huge_free(struct header *head, unsigned long poolsize, void *free)
 651 {
 652         unsigned long i, off, pgnum, free_off = (char *)free - (char *)head;
 653         unsigned int sp_bits, lp_bits;
 654         struct huge_alloc *ha;
 655
 656         for (i = head->huge; i; i = ha->next) {
 657                 ha = (void *)((char *)head + i);
 658                 if (free_off == ha->off)
 659                         break;
 660         }
 661         assert(i);
 662
 663         /* Free up all the pages, delete and free ha */
 664         sp_bits = small_page_bits(poolsize);
 665         lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
 666         pgnum = free_off >> sp_bits;
 667
 668         if (test_bit(head->pagesize, pgnum >> BITS_FROM_SMALL_TO_LARGE_PAGE)) {
 669                 for (off = ha->off;
 670                      off < ha->off + ha->len;
 671                      off += 1UL << lp_bits) {
 672                         add_large_page_to_freelist(head,
 673                                                    (void *)((char *)head + off),
 674                                                    sp_bits);
 675                 }
 676         } else {
 677                 for (off = ha->off;
 678                      off < ha->off + ha->len;
 679                      off += 1UL << sp_bits) {
 680                         add_small_page_to_freelist(head,
 681                                                    (void *)((char *)head + off),
 682                                                    sp_bits);
 683                 }
 684         }
 685         del_from_huge(head, ha);
 686         alloc_free(head, poolsize, ha);
 687 }
 688
 689 static COLD unsigned long huge_size(struct header *head, void *p)
 690 {
 691         unsigned long i, off = (char *)p - (char *)head;
 692         struct huge_alloc *ha;
 693
 694         for (i = head->huge; i; i = ha->next) {
 695                 ha = (void *)((char *)head + i);
 696                 if (off == ha->off) {
 697                         return ha->len;
 698                 }
 699         }
 700         abort();
 701 }
 702
 703 void *alloc_get(void *pool, unsigned long poolsize,
 704                 unsigned long size, unsigned long align)
 705 {
 706         struct header *head = pool;
 707         unsigned int bucket;
 708         unsigned long i;
 709         struct bucket_state *bs;
 710         struct page_header *ph;
 711         unsigned int sp_bits;
 712
 713         if (poolsize < MIN_USEFUL_SIZE) {
 714                 return tiny_alloc_get(pool, poolsize, size, align);
 715         }
 716
 717         size = align_up(size, align);
 718         if (unlikely(!size))
 719                 size = 1;
 720         bucket = size_to_bucket(size);
 721
 722         sp_bits = small_page_bits(poolsize);
 723
 724         if (bucket >= max_bucket(sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE)) {
 725                 return huge_alloc(pool, poolsize, size, align);
 726         }
 727
 728         bs = &head->bs[bucket];
 729
 730         if (!bs->page_list) {
 731                 struct page_header *ph;
 732
 733                 if (large_page_bucket(bucket, sp_bits))
 734                         bs->page_list = get_large_page(head, poolsize,
 735                                                        sp_bits);
 736                 else
 737                         bs->page_list = get_small_page(head, poolsize,
 738                                                        sp_bits);
 739                 /* FIXME: Try large-aligned alloc?  Header stuffing? */
 740                 if (unlikely(!bs->page_list))
 741                         return NULL;
 742                 ph = from_pgnum(head, bs->page_list, sp_bits);
 743                 ph->bucket = bucket;
 744                 ph->elements_used = 0;
 745                 ph->next = 0;
 746                 memset(ph->used, 0, used_size(bs->elements_per_page));
 747         }
 748
 749         ph = from_pgnum(head, bs->page_list, sp_bits);
 750
 751         i = find_free_bit(ph->used);
 752         set_bit(ph->used, i);
 753         ph->elements_used++;
 754
 755         /* check if this page is now full */
 756         if (unlikely(ph->elements_used == bs->elements_per_page)) {
 757                 del_from_bucket_list(head, bs, ph, sp_bits);
 758                 add_to_bucket_full_list(head, bs, ph, sp_bits);
 759         }
 760
 761         return (char *)ph + page_header_size(ph->bucket / INTER_BUCKET_SPACE,
 762                                              bs->elements_per_page)
 763                + i * bucket_to_size(bucket);
 764 }
 765
 766 void alloc_free(void *pool, unsigned long poolsize, void *free)
 767 {
 768         struct header *head = pool;
 769         struct bucket_state *bs;
 770         unsigned int sp_bits;
 771         unsigned long i, pgnum, pgoffset, offset = (char *)free - (char *)pool;
 772         bool smallpage;
 773         struct page_header *ph;
 774
 775         if (poolsize < MIN_USEFUL_SIZE) {
 776                 return tiny_alloc_free(pool, poolsize, free);
 777         }
 778
 779         /* Get page header. */
 780         sp_bits = small_page_bits(poolsize);
 781         pgnum = offset >> sp_bits;
 782
 783         /* Big page? Round down further. */
 784         if (test_bit(head->pagesize, pgnum >> BITS_FROM_SMALL_TO_LARGE_PAGE)) {
 785                 smallpage = false;
 786                 pgnum &= ~(SMALL_PAGES_PER_LARGE_PAGE - 1);
 787         } else
 788                 smallpage = true;
 789
 790         /* Step back to page header. */
 791         ph = from_pgnum(head, pgnum, sp_bits);
 792         if ((void *)ph == free) {
 793                 huge_free(head, poolsize, free);
 794                 return;
 795         }
 796
 797         bs = &head->bs[ph->bucket];
 798         pgoffset = offset - (pgnum << sp_bits)
 799                 - page_header_size(ph->bucket / INTER_BUCKET_SPACE,
 800                                    bs->elements_per_page);
 801
 802         if (unlikely(ph->elements_used == bs->elements_per_page)) {
 803                 del_from_bucket_full_list(head, bs, ph, sp_bits);
 804                 add_to_bucket_list(head, bs, ph, sp_bits);
 805         }
 806
 807         /* Which element are we? */
 808         i = pgoffset / bucket_to_size(ph->bucket);
 809         clear_bit(ph->used, i);
 810         ph->elements_used--;
 811
 812         if (unlikely(ph->elements_used == 0)) {
 813                 bs = &head->bs[ph->bucket];
 814                 del_from_bucket_list(head, bs, ph, sp_bits);
 815                 if (smallpage)
 816                         add_small_page_to_freelist(head, ph, sp_bits);
 817                 else
 818                         add_large_page_to_freelist(head, ph, sp_bits);
 819         }
 820 }
 821
 822 unsigned long alloc_size(void *pool, unsigned long poolsize, void *p)
 823 {
 824         struct header *head = pool;
 825         unsigned int pgnum, sp_bits;
 826         unsigned long offset = (char *)p - (char *)pool;
 827         struct page_header *ph;
 828
 829         if (poolsize < MIN_USEFUL_SIZE)
 830                 return tiny_alloc_size(pool, poolsize, p);
 831
 832         /* Get page header. */
 833         sp_bits = small_page_bits(poolsize);
 834         pgnum = offset >> sp_bits;
 835
 836         /* Big page? Round down further. */
 837         if (test_bit(head->pagesize, pgnum >> BITS_FROM_SMALL_TO_LARGE_PAGE))
 838                 pgnum &= ~(SMALL_PAGES_PER_LARGE_PAGE - 1);
 839
 840         /* Step back to page header. */
 841         ph = from_pgnum(head, pgnum, sp_bits);
 842         if ((void *)ph == p)
 843                 return huge_size(head, p);
 844
 845         return bucket_to_size(ph->bucket);
 846 }
 847
 848 /* Useful for gdb breakpoints. */
 849 static bool check_fail(void)
 850 {
 851         return false;
 852 }
 853
 854 static unsigned long count_bits(const unsigned long bitmap[],
 855                                 unsigned long limit)
 856 {
 857         unsigned long i, count = 0;
 858
 859         while (limit >= BITS_PER_LONG) {
 860                 count += popcount(bitmap[0]);
 861                 bitmap++;
 862                 limit -= BITS_PER_LONG;
 863         }
 864
 865         for (i = 0; i < limit; i++)
 866                 if (test_bit(bitmap, i))
 867                         count++;
 868         return count;
 869 }
 870
 871 static bool out_of_bounds(unsigned long pgnum,
 872                           unsigned int sp_bits,
 873                           unsigned long pagesize,
 874                           unsigned long poolsize)
 875 {
 876         if (((pgnum << sp_bits) >> sp_bits) != pgnum)
 877                 return true;
 878
 879         if ((pgnum << sp_bits) > poolsize)
 880                 return true;
 881
 882         return ((pgnum << sp_bits) + pagesize > poolsize);
 883 }
 884
 885 static bool check_bucket(struct header *head,
 886                          unsigned long poolsize,
 887                          unsigned long pages[],
 888                          struct bucket_state *bs,
 889                          unsigned int bindex)
 890 {
 891         bool lp_bucket;
 892         struct page_header *ph;
 893         unsigned long taken, i, prev, pagesize, sp_bits, lp_bits;
 894
 895         sp_bits = small_page_bits(poolsize);
 896         lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
 897
 898         lp_bucket = large_page_bucket(bindex, sp_bits);
 899
 900         pagesize = 1UL << (lp_bucket ? lp_bits : sp_bits);
 901
 902         /* This many elements fit? */
 903         taken = page_header_size(bindex / INTER_BUCKET_SPACE,
 904                                  bs->elements_per_page);
 905         taken += bucket_to_size(bindex) * bs->elements_per_page;
 906         if (taken > pagesize)
 907                 return check_fail();
 908
 909         /* One more wouldn't fit? */
 910         taken = page_header_size(bindex / INTER_BUCKET_SPACE,
 911                                  bs->elements_per_page + 1);
 912         taken += bucket_to_size(bindex) * (bs->elements_per_page + 1);
 913         if (taken <= pagesize)
 914                 return check_fail();
 915
 916         /* Walk used list. */
 917         prev = 0;
 918         for (i = bs->page_list; i; i = ph->next) {
 919                 /* Bad pointer? */
 920                 if (out_of_bounds(i, sp_bits, pagesize, poolsize))
 921                         return check_fail();
 922                 /* Wrong size page? */
 923                 if (!!test_bit(head->pagesize, i >> BITS_FROM_SMALL_TO_LARGE_PAGE)
 924                     != lp_bucket)
 925                         return check_fail();
 926                 /* Large page not on boundary? */
 927                 if (lp_bucket && (i % SMALL_PAGES_PER_LARGE_PAGE) != 0)
 928                         return check_fail();
 929                 ph = from_pgnum(head, i, sp_bits);
 930                 /* Linked list corrupt? */
 931                 if (ph->prev != prev)
 932                         return check_fail();
 933                 /* Already seen this page? */
 934                 if (test_bit(pages, i))
 935                         return check_fail();
 936                 set_bit(pages, i);
 937                 /* Empty or full? */
 938                 if (ph->elements_used == 0)
 939                         return check_fail();
 940                 if (ph->elements_used >= bs->elements_per_page)
 941                         return check_fail();
 942                 /* Used bits don't agree? */
 943                 if (ph->elements_used != count_bits(ph->used,
 944                                                     bs->elements_per_page))
 945                         return check_fail();
 946                 /* Wrong bucket? */
 947                 if (ph->bucket != bindex)
 948                         return check_fail();
 949                 prev = i;
 950         }
 951
 952         /* Walk full list. */
 953         prev = 0;
 954         for (i = bs->full_list; i; i = ph->next) {
 955                 /* Bad pointer? */
 956                 if (out_of_bounds(i, sp_bits, pagesize, poolsize))
 957                         return check_fail();
 958                 /* Wrong size page? */
 959                 if (!!test_bit(head->pagesize, i >> BITS_FROM_SMALL_TO_LARGE_PAGE)
 960                     != lp_bucket)
 961                 /* Large page not on boundary? */
 962                 if (lp_bucket && (i % SMALL_PAGES_PER_LARGE_PAGE) != 0)
 963                         return check_fail();
 964                 ph = from_pgnum(head, i, sp_bits);
 965                 /* Linked list corrupt? */
 966                 if (ph->prev != prev)
 967                         return check_fail();
 968                 /* Already seen this page? */
 969                 if (test_bit(pages, i))
 970                         return check_fail();
 971                 set_bit(pages, i);
 972                 /* Not full? */
 973                 if (ph->elements_used != bs->elements_per_page)
 974                         return check_fail();
 975                 /* Used bits don't agree? */
 976                 if (ph->elements_used != count_bits(ph->used,
 977                                                     bs->elements_per_page))
 978                         return check_fail();
 979                 /* Wrong bucket? */
 980                 if (ph->bucket != bindex)
 981                         return check_fail();
 982                 prev = i;
 983         }
 984         return true;
 985 }
 986
 987 bool alloc_check(void *pool, unsigned long poolsize)
 988 {
 989         struct header *head = pool;
 990         unsigned long prev, i, lp_bits, sp_bits, header_size, num_buckets;
 991         struct page_header *ph;
 992         struct huge_alloc *ha;
 993         unsigned long pages[MAX_SMALL_PAGES / BITS_PER_LONG] = { 0 };
 994
 995         if (poolsize < MIN_USEFUL_SIZE)
 996                 return tiny_alloc_check(pool, poolsize);
 997
 998         sp_bits = small_page_bits(poolsize);
 999         lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
1000
1001         num_buckets = max_bucket(lp_bits);
1002
1003         header_size = sizeof(*head) + sizeof(head->bs) * (num_buckets-1);
1004
1005         /* First, set all bits taken by header. */
1006         for (i = 0; i < header_size; i += (1UL << sp_bits))
1007                 set_bit(pages, i >> sp_bits);
1008
1009         /* Check small page free list. */
1010         prev = 0;
1011         for (i = head->small_free_list; i; i = ph->next) {
1012                 /* Bad pointer? */
1013                 if (out_of_bounds(i, sp_bits, 1UL << sp_bits, poolsize))
1014                         return check_fail();
1015                 /* Large page? */
1016                 if (test_bit(head->pagesize, i >> BITS_FROM_SMALL_TO_LARGE_PAGE))
1017                         return check_fail();
1018                 ph = from_pgnum(head, i, sp_bits);
1019                 /* Linked list corrupt? */
1020                 if (ph->prev != prev)
1021                         return check_fail();
1022                 /* Already seen this page? */
1023                 if (test_bit(pages, i))
1024                         return check_fail();
1025                 set_bit(pages, i);
1026                 prev = i;
1027         }
1028
1029         /* Check large page free list. */
1030         prev = 0;
1031         for (i = head->large_free_list; i; i = ph->next) {
1032                 /* Bad pointer? */
1033                 if (out_of_bounds(i, sp_bits, 1UL << lp_bits, poolsize))
1034                         return check_fail();
1035                 /* Not large page? */
1036                 if (!test_bit(head->pagesize, i >> BITS_FROM_SMALL_TO_LARGE_PAGE))
1037                         return check_fail();
1038                 /* Not page boundary? */
1039                 if ((i % SMALL_PAGES_PER_LARGE_PAGE) != 0)
1040                         return check_fail();
1041                 ph = from_pgnum(head, i, sp_bits);
1042                 /* Linked list corrupt? */
1043                 if (ph->prev != prev)
1044                         return check_fail();
1045                 /* Already seen this page? */
1046                 if (test_bit(pages, i))
1047                         return check_fail();
1048                 set_bit(pages, i);
1049                 prev = i;
1050         }
1051
1052         /* Check the buckets. */
1053         for (i = 0; i < max_bucket(lp_bits); i++) {
1054                 struct bucket_state *bs = &head->bs[i];
1055
1056                 if (!check_bucket(head, poolsize, pages, bs, i))
1057                         return false;
1058         }
1059
1060         /* Check the huge alloc list. */
1061         prev = 0;
1062         for (i = head->huge; i; i = ha->next) {
1063                 unsigned long pgbits, j;
1064
1065                 /* Bad pointer? */
1066                 if (i >= poolsize || i + sizeof(*ha) > poolsize)
1067                         return check_fail();
1068                 ha = (void *)((char *)head + i);
1069
1070                 /* Check contents of ha. */
1071                 if (ha->off > poolsize || ha->off + ha->len > poolsize)
1072                         return check_fail();
1073
1074                 /* Large or small page? */
1075                 pgbits = test_bit(head->pagesize, ha->off >> lp_bits)
1076                         ? lp_bits : sp_bits;
1077
1078                 /* Not page boundary? */
1079                 if ((ha->off % (1UL << pgbits)) != 0)
1080                         return check_fail();
1081
1082                 /* Not page length? */
1083                 if ((ha->len % (1UL << pgbits)) != 0)
1084                         return check_fail();
1085
1086                 /* Linked list corrupt? */
1087                 if (ha->prev != prev)
1088                         return check_fail();
1089
1090                 for (j = ha->off; j < ha->off + ha->len; j += (1UL<<sp_bits)) {
1091                         /* Already seen this page? */
1092                         if (test_bit(pages, j >> sp_bits))
1093                                 return check_fail();
1094                         set_bit(pages, j >> sp_bits);
1095                 }
1096
1097                 prev = i;
1098         }
1099
1100         /* Make sure every page accounted for. */
1101         for (i = 0; i < poolsize >> sp_bits; i++) {
1102                 if (!test_bit(pages, i))
1103                         return check_fail();
1104                 if (test_bit(head->pagesize,
1105                              i >> BITS_FROM_SMALL_TO_LARGE_PAGE)) {
1106                         /* Large page, skip rest. */
1107                         i += SMALL_PAGES_PER_LARGE_PAGE - 1;
1108                 }
1109         }
1110
1111         return true;
1112 }
1113
1114 static unsigned long print_overhead(FILE *out, const char *desc,
1115                                     unsigned long bytes,
1116                                     unsigned long poolsize)
1117 {
1118         fprintf(out, "Overhead (%s): %lu bytes (%.3g%%)\n",
1119                 desc, bytes, 100.0 * bytes / poolsize);
1120         return bytes;
1121 }
1122
1123 static unsigned long count_list(struct header *head,
1124                                 u16 pgnum,
1125                                 unsigned int sp_bits,
1126                                 unsigned long *total_elems)
1127 {
1128         struct page_header *p;
1129         unsigned long ret = 0;
1130
1131         while (pgnum) {
1132                 p = from_pgnum(head, pgnum, sp_bits);
1133                 if (total_elems)
1134                         (*total_elems) += p->elements_used;
1135                 ret++;
1136                 pgnum = p->next;
1137         }
1138         return ret;
1139 }
1140
1141 static unsigned long visualize_bucket(FILE *out, struct header *head,
1142                                       unsigned int bucket,
1143                                       unsigned long poolsize,
1144                                       unsigned int sp_bits)
1145 {
1146         unsigned long num_full, num_partial, num_pages, page_size,
1147                 elems, hdr_min, hdr_size, elems_per_page, overhead = 0;
1148
1149         elems_per_page = head->bs[bucket].elements_per_page;
1150
1151         /* If we used byte-based bitmaps, we could get pg hdr to: */
1152         hdr_min = sizeof(struct page_header)
1153                 - sizeof(((struct page_header *)0)->used)
1154                 + align_up(elems_per_page, CHAR_BIT) / CHAR_BIT;
1155         hdr_size = page_header_size(bucket / INTER_BUCKET_SPACE,
1156                                     elems_per_page);
1157
1158         elems = 0;
1159         num_full = count_list(head, head->bs[bucket].full_list, sp_bits,
1160                               &elems);
1161         num_partial = count_list(head, head->bs[bucket].page_list, sp_bits,
1162                                  &elems);
1163         num_pages = num_full + num_partial;
1164         if (!num_pages)
1165                 return 0;
1166
1167         fprintf(out, "Bucket %u (%lu bytes):"
1168                 " %lu full, %lu partial = %lu elements\n",
1169                 bucket, bucket_to_size(bucket), num_full, num_partial, elems);
1170         /* Strict requirement of page header size. */
1171         overhead += print_overhead(out, "page headers",
1172                                    hdr_min * num_pages, poolsize);
1173         /* Gap between minimal page header and actual start. */
1174         overhead += print_overhead(out, "page post-header alignments",
1175                                    (hdr_size - hdr_min) * num_pages, poolsize);
1176         /* Between last element and end of page. */
1177         page_size = (1UL << sp_bits);
1178         if (large_page_bucket(bucket, sp_bits))
1179                 page_size <<= BITS_FROM_SMALL_TO_LARGE_PAGE;
1180
1181         overhead += print_overhead(out, "page tails",
1182                                    (page_size - (hdr_size
1183                                                  + (elems_per_page
1184                                                     * bucket_to_size(bucket))))
1185                                    * num_pages, poolsize);
1186         return overhead;
1187 }
1188
1189 void alloc_visualize(FILE *out, void *pool, unsigned long poolsize)
1190 {
1191         struct header *head = pool;
1192         unsigned long i, lp_bits, sp_bits, header_size, num_buckets, count,
1193                 overhead = 0;
1194
1195         fprintf(out, "Pool %p size %lu: (%s allocator)\n", pool, poolsize,
1196                 poolsize < MIN_USEFUL_SIZE ? "tiny" : "standard");
1197
1198         if (poolsize < MIN_USEFUL_SIZE) {
1199                 tiny_alloc_visualize(out, pool, poolsize);
1200                 return;
1201         }
1202
1203         sp_bits = small_page_bits(poolsize);
1204         lp_bits = sp_bits + BITS_FROM_SMALL_TO_LARGE_PAGE;
1205
1206         num_buckets = max_bucket(lp_bits);
1207         header_size = sizeof(*head) + sizeof(head->bs) * (num_buckets-1);
1208
1209         fprintf(out, "Large page size %lu, small page size %lu.\n",
1210                 1UL << lp_bits, 1UL << sp_bits);
1211         overhead += print_overhead(out, "unused pool tail",
1212                                    poolsize % (1UL << lp_bits), poolsize);
1213         fprintf(out, "Main header %lu bytes (%lu small pages).\n",
1214                 header_size, align_up(header_size, 1UL << sp_bits) >> sp_bits);
1215         overhead += print_overhead(out, "partial header page",
1216                                    align_up(header_size, 1UL << sp_bits)
1217                                    - header_size, poolsize);
1218         /* Total large pages. */
1219         i = count_bits(head->pagesize, poolsize >> lp_bits);
1220         /* Used pages. */
1221         count = i - count_list(head, head->large_free_list, sp_bits, NULL);
1222         fprintf(out, "%lu/%lu large pages used (%.3g%%)\n",
1223                 count, i, count ? 100.0 * count / i : 0.0);
1224
1225         /* Total small pages. */
1226         i = ((poolsize >> lp_bits) - i) << BITS_FROM_SMALL_TO_LARGE_PAGE;
1227         /* Used pages */
1228         count = i - count_list(head, head->small_free_list, sp_bits, NULL);
1229         fprintf(out, "%lu/%lu small pages used (%.3g%%)\n",
1230                 count, i, count ? 100.0 * count / i : 0.0);
1231
1232         /* Summary of each bucket. */
1233         fprintf(out, "%lu buckets:\n", num_buckets);
1234         for (i = 0; i < num_buckets; i++)
1235                 overhead += visualize_bucket(out, head, i, poolsize, sp_bits);
1236
1237         print_overhead(out, "total", overhead, poolsize);
1238 }