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