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