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