mm/bootmem.c

   1 /*
   2  *  linux/mm/bootmem.c
   3  *
   4  *  Copyright (C) 1999 Ingo Molnar
   5  *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
   6  *
   7  *  simple boot-time physical memory area allocator and
   8  *  free memory collector. It's used to deal with reserved
   9  *  system memory and memory holes as well.
  10  */
  11 #include <linux/init.h>
  12 #include <linux/pfn.h>
  13 #include <linux/bootmem.h>
  14 #include <linux/module.h>
  15
  16 #include <asm/bug.h>
  17 #include <asm/io.h>
  18 #include <asm/processor.h>
  19
  20 #include "internal.h"
  21
  22 /*
  23  * Access to this subsystem has to be serialized externally. (this is
  24  * true for the boot process anyway)
  25  */
  26 unsigned long max_low_pfn;
  27 unsigned long min_low_pfn;
  28 unsigned long max_pfn;
  29
  30 static LIST_HEAD(bdata_list);
  31 #ifdef CONFIG_CRASH_DUMP
  32 /*
  33  * If we have booted due to a crash, max_pfn will be a very low value. We need
  34  * to know the amount of memory that the previous kernel used.
  35  */
  36 unsigned long saved_max_pfn;
  37 #endif
  38
  39 /* return the number of _pages_ that will be allocated for the boot bitmap */
  40 unsigned long __init bootmem_bootmap_pages(unsigned long pages)
  41 {
  42         unsigned long mapsize;
  43
  44         mapsize = (pages+7)/8;
  45         mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;
  46         mapsize >>= PAGE_SHIFT;
  47
  48         return mapsize;
  49 }
  50
  51 /*
  52  * link bdata in order
  53  */
  54 static void __init link_bootmem(bootmem_data_t *bdata)
  55 {
  56         bootmem_data_t *ent;
  57
  58         if (list_empty(&bdata_list)) {
  59                 list_add(&bdata->list, &bdata_list);
  60                 return;
  61         }
  62         /* insert in order */
  63         list_for_each_entry(ent, &bdata_list, list) {
  64                 if (bdata->node_boot_start < ent->node_boot_start) {
  65                         list_add_tail(&bdata->list, &ent->list);
  66                         return;
  67                 }
  68         }
  69         list_add_tail(&bdata->list, &bdata_list);
  70 }
  71
  72 /*
  73  * Given an initialised bdata, it returns the size of the boot bitmap
  74  */
  75 static unsigned long __init get_mapsize(bootmem_data_t *bdata)
  76 {
  77         unsigned long mapsize;
  78         unsigned long start = PFN_DOWN(bdata->node_boot_start);
  79         unsigned long end = bdata->node_low_pfn;
  80
  81         mapsize = ((end - start) + 7) / 8;
  82         return ALIGN(mapsize, sizeof(long));
  83 }
  84
  85 /*
  86  * Called once to set up the allocator itself.
  87  */
  88 static unsigned long __init init_bootmem_core(pg_data_t *pgdat,
  89         unsigned long mapstart, unsigned long start, unsigned long end)
  90 {
  91         bootmem_data_t *bdata = pgdat->bdata;
  92         unsigned long mapsize;
  93
  94         bdata->node_bootmem_map = phys_to_virt(PFN_PHYS(mapstart));
  95         bdata->node_boot_start = PFN_PHYS(start);
  96         bdata->node_low_pfn = end;
  97         link_bootmem(bdata);
  98
  99         /*
 100          * Initially all pages are reserved - setup_arch() has to
 101          * register free RAM areas explicitly.
 102          */
 103         mapsize = get_mapsize(bdata);
 104         memset(bdata->node_bootmem_map, 0xff, mapsize);
 105
 106         return mapsize;
 107 }
 108
 109 /*
 110  * Marks a particular physical memory range as unallocatable. Usable RAM
 111  * might be used for boot-time allocations - or it might get added
 112  * to the free page pool later on.
 113  */
 114 static int __init reserve_bootmem_core(bootmem_data_t *bdata,
 115                         unsigned long addr, unsigned long size, int flags)
 116 {
 117         unsigned long sidx, eidx;
 118         unsigned long i;
 119         int ret;
 120
 121         /*
 122          * round up, partially reserved pages are considered
 123          * fully reserved.
 124          */
 125         BUG_ON(!size);
 126         BUG_ON(PFN_DOWN(addr) >= bdata->node_low_pfn);
 127         BUG_ON(PFN_UP(addr + size) > bdata->node_low_pfn);
 128
 129         sidx = PFN_DOWN(addr - bdata->node_boot_start);
 130         eidx = PFN_UP(addr + size - bdata->node_boot_start);
 131
 132         for (i = sidx; i < eidx; i++)
 133                 if (test_and_set_bit(i, bdata->node_bootmem_map)) {
 134 #ifdef CONFIG_DEBUG_BOOTMEM
 135                         printk("hm, page %08lx reserved twice.\n", i*PAGE_SIZE);
 136 #endif
 137                         if (flags & BOOTMEM_EXCLUSIVE) {
 138                                 ret = -EBUSY;
 139                                 goto err;
 140                         }
 141                 }
 142
 143         return 0;
 144
 145 err:
 146         /* unreserve memory we accidentally reserved */
 147         for (i--; i >= sidx; i--)
 148                 clear_bit(i, bdata->node_bootmem_map);
 149
 150         return ret;
 151 }
 152
 153 static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr,
 154                                      unsigned long size)
 155 {
 156         unsigned long sidx, eidx;
 157         unsigned long i;
 158
 159         /*
 160          * round down end of usable mem, partially free pages are
 161          * considered reserved.
 162          */
 163         BUG_ON(!size);
 164         BUG_ON(PFN_DOWN(addr + size) > bdata->node_low_pfn);
 165
 166         if (addr < bdata->last_success)
 167                 bdata->last_success = addr;
 168
 169         /*
 170          * Round up the beginning of the address.
 171          */
 172         sidx = PFN_UP(addr) - PFN_DOWN(bdata->node_boot_start);
 173         eidx = PFN_DOWN(addr + size - bdata->node_boot_start);
 174
 175         for (i = sidx; i < eidx; i++) {
 176                 if (unlikely(!test_and_clear_bit(i, bdata->node_bootmem_map)))
 177                         BUG();
 178         }
 179 }
 180
 181 /*
 182  * We 'merge' subsequent allocations to save space. We might 'lose'
 183  * some fraction of a page if allocations cannot be satisfied due to
 184  * size constraints on boxes where there is physical RAM space
 185  * fragmentation - in these cases (mostly large memory boxes) this
 186  * is not a problem.
 187  *
 188  * On low memory boxes we get it right in 100% of the cases.
 189  *
 190  * alignment has to be a power of 2 value.
 191  *
 192  * NOTE:  This function is _not_ reentrant.
 193  */
 194 void * __init
 195 __alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
 196               unsigned long align, unsigned long goal, unsigned long limit)
 197 {
 198         unsigned long offset, remaining_size, areasize, preferred;
 199         unsigned long i, start = 0, incr, eidx, end_pfn;
 200         void *ret;
 201
 202         if (!size) {
 203                 printk("__alloc_bootmem_core(): zero-sized request\n");
 204                 BUG();
 205         }
 206         BUG_ON(align & (align-1));
 207
 208         if (limit && bdata->node_boot_start >= limit)
 209                 return NULL;
 210
 211         /* on nodes without memory - bootmem_map is NULL */
 212         if (!bdata->node_bootmem_map)
 213                 return NULL;
 214
 215         end_pfn = bdata->node_low_pfn;
 216         limit = PFN_DOWN(limit);
 217         if (limit && end_pfn > limit)
 218                 end_pfn = limit;
 219
 220         eidx = end_pfn - PFN_DOWN(bdata->node_boot_start);
 221         offset = 0;
 222         if (align && (bdata->node_boot_start & (align - 1UL)) != 0)
 223                 offset = align - (bdata->node_boot_start & (align - 1UL));
 224         offset = PFN_DOWN(offset);
 225
 226         /*
 227          * We try to allocate bootmem pages above 'goal'
 228          * first, then we try to allocate lower pages.
 229          */
 230         if (goal && goal >= bdata->node_boot_start && PFN_DOWN(goal) < end_pfn) {
 231                 preferred = goal - bdata->node_boot_start;
 232
 233                 if (bdata->last_success >= preferred)
 234                         if (!limit || (limit && limit > bdata->last_success))
 235                                 preferred = bdata->last_success;
 236         } else
 237                 preferred = 0;
 238
 239         preferred = PFN_DOWN(ALIGN(preferred, align)) + offset;
 240         areasize = (size + PAGE_SIZE-1) / PAGE_SIZE;
 241         incr = align >> PAGE_SHIFT ? : 1;
 242
 243 restart_scan:
 244         for (i = preferred; i < eidx; i += incr) {
 245                 unsigned long j;
 246                 i = find_next_zero_bit(bdata->node_bootmem_map, eidx, i);
 247                 i = ALIGN(i, incr);
 248                 if (i >= eidx)
 249                         break;
 250                 if (test_bit(i, bdata->node_bootmem_map))
 251                         continue;
 252                 for (j = i + 1; j < i + areasize; ++j) {
 253                         if (j >= eidx)
 254                                 goto fail_block;
 255                         if (test_bit(j, bdata->node_bootmem_map))
 256                                 goto fail_block;
 257                 }
 258                 start = i;
 259                 goto found;
 260         fail_block:
 261                 i = ALIGN(j, incr);
 262         }
 263
 264         if (preferred > offset) {
 265                 preferred = offset;
 266                 goto restart_scan;
 267         }
 268         return NULL;
 269
 270 found:
 271         bdata->last_success = PFN_PHYS(start);
 272         BUG_ON(start >= eidx);
 273
 274         /*
 275          * Is the next page of the previous allocation-end the start
 276          * of this allocation's buffer? If yes then we can 'merge'
 277          * the previous partial page with this allocation.
 278          */
 279         if (align < PAGE_SIZE &&
 280             bdata->last_offset && bdata->last_pos+1 == start) {
 281                 offset = ALIGN(bdata->last_offset, align);
 282                 BUG_ON(offset > PAGE_SIZE);
 283                 remaining_size = PAGE_SIZE - offset;
 284                 if (size < remaining_size) {
 285                         areasize = 0;
 286                         /* last_pos unchanged */
 287                         bdata->last_offset = offset + size;
 288                         ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
 289                                            offset +
 290                                            bdata->node_boot_start);
 291                 } else {
 292                         remaining_size = size - remaining_size;
 293                         areasize = (remaining_size + PAGE_SIZE-1) / PAGE_SIZE;
 294                         ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
 295                                            offset +
 296                                            bdata->node_boot_start);
 297                         bdata->last_pos = start + areasize - 1;
 298                         bdata->last_offset = remaining_size;
 299                 }
 300                 bdata->last_offset &= ~PAGE_MASK;
 301         } else {
 302                 bdata->last_pos = start + areasize - 1;
 303                 bdata->last_offset = size & ~PAGE_MASK;
 304                 ret = phys_to_virt(start * PAGE_SIZE + bdata->node_boot_start);
 305         }
 306
 307         /*
 308          * Reserve the area now:
 309          */
 310         for (i = start; i < start + areasize; i++)
 311                 if (unlikely(test_and_set_bit(i, bdata->node_bootmem_map)))
 312                         BUG();
 313         memset(ret, 0, size);
 314         return ret;
 315 }
 316
 317 static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
 318 {
 319         struct page *page;
 320         unsigned long pfn;
 321         bootmem_data_t *bdata = pgdat->bdata;
 322         unsigned long i, count, total = 0;
 323         unsigned long idx;
 324         unsigned long *map;
 325         int gofast = 0;
 326
 327         BUG_ON(!bdata->node_bootmem_map);
 328
 329         count = 0;
 330         /* first extant page of the node */
 331         pfn = PFN_DOWN(bdata->node_boot_start);
 332         idx = bdata->node_low_pfn - pfn;
 333         map = bdata->node_bootmem_map;
 334         /* Check physaddr is O(LOG2(BITS_PER_LONG)) page aligned */
 335         if (bdata->node_boot_start == 0 ||
 336             ffs(bdata->node_boot_start) - PAGE_SHIFT > ffs(BITS_PER_LONG))
 337                 gofast = 1;
 338         for (i = 0; i < idx; ) {
 339                 unsigned long v = ~map[i / BITS_PER_LONG];
 340
 341                 if (gofast && v == ~0UL) {
 342                         int order;
 343
 344                         page = pfn_to_page(pfn);
 345                         count += BITS_PER_LONG;
 346                         order = ffs(BITS_PER_LONG) - 1;
 347                         __free_pages_bootmem(page, order);
 348                         i += BITS_PER_LONG;
 349                         page += BITS_PER_LONG;
 350                 } else if (v) {
 351                         unsigned long m;
 352
 353                         page = pfn_to_page(pfn);
 354                         for (m = 1; m && i < idx; m<<=1, page++, i++) {
 355                                 if (v & m) {
 356                                         count++;
 357                                         __free_pages_bootmem(page, 0);
 358                                 }
 359                         }
 360                 } else {
 361                         i += BITS_PER_LONG;
 362                 }
 363                 pfn += BITS_PER_LONG;
 364         }
 365         total += count;
 366
 367         /*
 368          * Now free the allocator bitmap itself, it's not
 369          * needed anymore:
 370          */
 371         page = virt_to_page(bdata->node_bootmem_map);
 372         count = 0;
 373         idx = (get_mapsize(bdata) + PAGE_SIZE-1) >> PAGE_SHIFT;
 374         for (i = 0; i < idx; i++, page++) {
 375                 __free_pages_bootmem(page, 0);
 376                 count++;
 377         }
 378         total += count;
 379         bdata->node_bootmem_map = NULL;
 380
 381         return total;
 382 }
 383
 384 unsigned long __init init_bootmem_node(pg_data_t *pgdat, unsigned long freepfn,
 385                                 unsigned long startpfn, unsigned long endpfn)
 386 {
 387         return init_bootmem_core(pgdat, freepfn, startpfn, endpfn);
 388 }
 389
 390 void __init reserve_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
 391                                  unsigned long size, int flags)
 392 {
 393         reserve_bootmem_core(pgdat->bdata, physaddr, size, flags);
 394 }
 395
 396 void __init free_bootmem_node(pg_data_t *pgdat, unsigned long physaddr,
 397                               unsigned long size)
 398 {
 399         free_bootmem_core(pgdat->bdata, physaddr, size);
 400 }
 401
 402 unsigned long __init free_all_bootmem_node(pg_data_t *pgdat)
 403 {
 404         return free_all_bootmem_core(pgdat);
 405 }
 406
 407 unsigned long __init init_bootmem(unsigned long start, unsigned long pages)
 408 {
 409         max_low_pfn = pages;
 410         min_low_pfn = start;
 411         return init_bootmem_core(NODE_DATA(0), start, 0, pages);
 412 }
 413
 414 #ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
 415 int __init reserve_bootmem(unsigned long addr, unsigned long size,
 416                             int flags)
 417 {
 418         return reserve_bootmem_core(NODE_DATA(0)->bdata, addr, size, flags);
 419 }
 420 #endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */
 421
 422 void __init free_bootmem(unsigned long addr, unsigned long size)
 423 {
 424         free_bootmem_core(NODE_DATA(0)->bdata, addr, size);
 425 }
 426
 427 unsigned long __init free_all_bootmem(void)
 428 {
 429         return free_all_bootmem_core(NODE_DATA(0));
 430 }
 431
 432 void * __init __alloc_bootmem_nopanic(unsigned long size, unsigned long align,
 433                                       unsigned long goal)
 434 {
 435         bootmem_data_t *bdata;
 436         void *ptr;
 437
 438         list_for_each_entry(bdata, &bdata_list, list) {
 439                 ptr = __alloc_bootmem_core(bdata, size, align, goal, 0);
 440                 if (ptr)
 441                         return ptr;
 442         }
 443         return NULL;
 444 }
 445
 446 void * __init __alloc_bootmem(unsigned long size, unsigned long align,
 447                               unsigned long goal)
 448 {
 449         void *mem = __alloc_bootmem_nopanic(size,align,goal);
 450
 451         if (mem)
 452                 return mem;
 453         /*
 454          * Whoops, we cannot satisfy the allocation request.
 455          */
 456         printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
 457         panic("Out of memory");
 458         return NULL;
 459 }
 460
 461
 462 void * __init __alloc_bootmem_node(pg_data_t *pgdat, unsigned long size,
 463                                    unsigned long align, unsigned long goal)
 464 {
 465         void *ptr;
 466
 467         ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal, 0);
 468         if (ptr)
 469                 return ptr;
 470
 471         return __alloc_bootmem(size, align, goal);
 472 }
 473
 474 #ifndef ARCH_LOW_ADDRESS_LIMIT
 475 #define ARCH_LOW_ADDRESS_LIMIT  0xffffffffUL
 476 #endif
 477
 478 void * __init __alloc_bootmem_low(unsigned long size, unsigned long align,
 479                                   unsigned long goal)
 480 {
 481         bootmem_data_t *bdata;
 482         void *ptr;
 483
 484         list_for_each_entry(bdata, &bdata_list, list) {
 485                 ptr = __alloc_bootmem_core(bdata, size, align, goal,
 486                                                 ARCH_LOW_ADDRESS_LIMIT);
 487                 if (ptr)
 488                         return ptr;
 489         }
 490
 491         /*
 492          * Whoops, we cannot satisfy the allocation request.
 493          */
 494         printk(KERN_ALERT "low bootmem alloc of %lu bytes failed!\n", size);
 495         panic("Out of low memory");
 496         return NULL;
 497 }
 498
 499 void * __init __alloc_bootmem_low_node(pg_data_t *pgdat, unsigned long size,
 500                                        unsigned long align, unsigned long goal)
 501 {
 502         return __alloc_bootmem_core(pgdat->bdata, size, align, goal,
 503                                     ARCH_LOW_ADDRESS_LIMIT);
 504 }