mm/bootmem.c

   1 /*
   2  *  linux/mm/initmem.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/swapctl.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/init.h>
  18 #include <linux/bootmem.h>
  19 #include <linux/mmzone.h>
  20 #include <asm/dma.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
  28 /* return the number of _pages_ that will be allocated for the boot bitmap */
  29 unsigned long __init bootmem_bootmap_pages (unsigned long pages)
  30 {
  31         unsigned long mapsize;
  32
  33         mapsize = (pages+7)/8;
  34         mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;
  35         mapsize >>= PAGE_SHIFT;
  36
  37         return mapsize;
  38 }
  39
  40 /*
  41  * Called once to set up the allocator itself.
  42  */
  43 static unsigned long __init init_bootmem_core (bootmem_data_t *bdata,
  44         unsigned long mapstart, unsigned long start, unsigned long end)
  45 {
  46         unsigned long mapsize = ((end - start)+7)/8;
  47
  48         mapsize = (mapsize + (sizeof(long) - 1UL)) & ~(sizeof(long) - 1UL);
  49         bdata->node_bootmem_map = phys_to_virt(mapstart << PAGE_SHIFT);
  50         bdata->node_boot_start = (start << PAGE_SHIFT);
  51         bdata->node_low_pfn = end;
  52
  53         /*
  54          * Initially all pages are reserved - setup_arch() has to
  55          * register free RAM areas explicitly.
  56          */
  57         memset(bdata->node_bootmem_map, 0xff, mapsize);
  58
  59         return mapsize;
  60 }
  61
  62 /*
  63  * Marks a particular physical memory range as unallocatable. Usable RAM
  64  * might be used for boot-time allocations - or it might get added
  65  * to the free page pool later on.
  66  */
  67 static void __init reserve_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
  68 {
  69         unsigned long i;
  70         /*
  71          * round up, partially reserved pages are considered
  72          * fully reserved.
  73          */
  74         unsigned long sidx = (addr - bdata->node_boot_start)/PAGE_SIZE;
  75         unsigned long eidx = (addr + size - bdata->node_boot_start +
  76                                                         PAGE_SIZE-1)/PAGE_SIZE;
  77         unsigned long end = (addr + size + PAGE_SIZE-1)/PAGE_SIZE;
  78
  79         if (!size) BUG();
  80
  81         if (end > bdata->node_low_pfn)
  82                 BUG();
  83         for (i = sidx; i < eidx; i++)
  84                 if (test_and_set_bit(i, bdata->node_bootmem_map))
  85                         BUG();
  86 }
  87
  88 static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
  89 {
  90         unsigned long i;
  91         unsigned long start;
  92         /*
  93          * round down end of usable mem, partially free pages are
  94          * considered reserved.
  95          */
  96         unsigned long sidx;
  97         unsigned long eidx = (addr + size - bdata->node_boot_start)/PAGE_SIZE;
  98         unsigned long end = (addr + size)/PAGE_SIZE;
  99
 100         if (!size) BUG();
 101         if (end > bdata->node_low_pfn)
 102                 BUG();
 103
 104         /*
 105          * Round up the beginning of the address.
 106          */
 107         start = (addr + PAGE_SIZE-1) / PAGE_SIZE;
 108         sidx = start - (bdata->node_boot_start/PAGE_SIZE);
 109
 110         for (i = sidx; i < eidx; i++) {
 111                 if (!test_and_clear_bit(i, bdata->node_bootmem_map))
 112                         BUG();
 113         }
 114 }
 115
 116 /*
 117  * We 'merge' subsequent allocations to save space. We might 'lose'
 118  * some fraction of a page if allocations cannot be satisfied due to
 119  * size constraints on boxes where there is physical RAM space
 120  * fragmentation - in these cases * (mostly large memory boxes) this
 121  * is not a problem.
 122  *
 123  * On low memory boxes we get it right in 100% of the cases.
 124  */
 125
 126 /*
 127  * alignment has to be a power of 2 value.
 128  */
 129 static void * __init __alloc_bootmem_core (bootmem_data_t *bdata,
 130         unsigned long size, unsigned long align, unsigned long goal)
 131 {
 132         unsigned long i, start = 0;
 133         void *ret;
 134         unsigned long offset, remaining_size;
 135         unsigned long areasize, preferred, incr;
 136         unsigned long eidx = bdata->node_low_pfn - (bdata->node_boot_start >>
 137                                                         PAGE_SHIFT);
 138
 139         if (!size) BUG();
 140
 141         /*
 142          * We try to allocate bootmem pages above 'goal'
 143          * first, then we try to allocate lower pages.
 144          */
 145         if (goal && (goal >= bdata->node_boot_start) &&
 146                         ((goal >> PAGE_SHIFT) < bdata->node_low_pfn)) {
 147                 preferred = goal - bdata->node_boot_start;
 148         } else
 149                 preferred = 0;
 150
 151         preferred = ((preferred + align - 1) & ~(align - 1)) >> PAGE_SHIFT;
 152         areasize = (size+PAGE_SIZE-1)/PAGE_SIZE;
 153         incr = align >> PAGE_SHIFT ? : 1;
 154
 155 restart_scan:
 156         for (i = preferred; i < eidx; i += incr) {
 157                 unsigned long j;
 158                 if (test_bit(i, bdata->node_bootmem_map))
 159                         continue;
 160                 for (j = i + 1; j < i + areasize; ++j) {
 161                         if (j >= eidx)
 162                                 goto fail_block;
 163                         if (test_bit (j, bdata->node_bootmem_map))
 164                                 goto fail_block;
 165                 }
 166                 start = i;
 167                 goto found;
 168         fail_block:;
 169         }
 170         if (preferred) {
 171                 preferred = 0;
 172                 goto restart_scan;
 173         }
 174         /*
 175          * Whoops, we cannot satisfy the allocation request.
 176          */
 177         BUG();
 178 found:
 179         if (start >= eidx)
 180                 BUG();
 181
 182         /*
 183          * Is the next page of the previous allocation-end the start
 184          * of this allocation's buffer? If yes then we can 'merge'
 185          * the previous partial page with this allocation.
 186          */
 187         if (align <= PAGE_SIZE
 188             && bdata->last_offset && bdata->last_pos+1 == start) {
 189                 offset = (bdata->last_offset+align-1) & ~(align-1);
 190                 if (offset > PAGE_SIZE)
 191                         BUG();
 192                 remaining_size = PAGE_SIZE-offset;
 193                 if (size < remaining_size) {
 194                         areasize = 0;
 195                         // last_pos unchanged
 196                         bdata->last_offset = offset+size;
 197                         ret = phys_to_virt(bdata->last_pos*PAGE_SIZE + offset +
 198                                                 bdata->node_boot_start);
 199                 } else {
 200                         remaining_size = size - remaining_size;
 201                         areasize = (remaining_size+PAGE_SIZE-1)/PAGE_SIZE;
 202                         ret = phys_to_virt(bdata->last_pos*PAGE_SIZE + offset +
 203                                                 bdata->node_boot_start);
 204                         bdata->last_pos = start+areasize-1;
 205                         bdata->last_offset = remaining_size;
 206                 }
 207                 bdata->last_offset &= ~PAGE_MASK;
 208         } else {
 209                 bdata->last_pos = start + areasize - 1;
 210                 bdata->last_offset = size & ~PAGE_MASK;
 211                 ret = phys_to_virt(start * PAGE_SIZE + bdata->node_boot_start);
 212         }
 213         /*
 214          * Reserve the area now:
 215          */
 216         for (i = start; i < start+areasize; i++)
 217                 if (test_and_set_bit(i, bdata->node_bootmem_map))
 218                         BUG();
 219         memset(ret, 0, size);
 220         return ret;
 221 }
 222
 223 static unsigned long __init free_all_bootmem_core(int nid, bootmem_data_t *bdata)
 224 {
 225         struct page * page;
 226         unsigned long i, count, total = 0;
 227         unsigned long idx;
 228
 229         if (!bdata->node_bootmem_map) BUG();
 230
 231         page = NODE_MEM_MAP(nid);
 232         count = 0;
 233         idx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
 234         for (i = 0; i < idx; i++, page++) {
 235                 if (!test_bit(i, bdata->node_bootmem_map)) {
 236                         count++;
 237                         ClearPageReserved(page);
 238                         set_page_count(page, 1);
 239                         __free_page(page);
 240                 }
 241         }
 242         total += count;
 243
 244         /*
 245          * Now free the allocator bitmap itself, it's not
 246          * needed anymore:
 247          */
 248         page = mem_map + MAP_NR(bdata->node_bootmem_map);
 249         count = 0;
 250         for (i = 0; i < ((bdata->node_low_pfn-(bdata->node_boot_start >> PAGE_SHIFT))/8 + PAGE_SIZE-1)/PAGE_SIZE; i++,page++) {
 251                 count++;
 252                 ClearPageReserved(page);
 253                 set_page_count(page, 1);
 254                 __free_page(page);
 255         }
 256         total += count;
 257         bdata->node_bootmem_map = NULL;
 258
 259         return total;
 260 }
 261
 262 unsigned long __init init_bootmem_node (int nid, unsigned long freepfn, unsigned long startpfn, unsigned long endpfn)
 263 {
 264         return(init_bootmem_core(NODE_DATA(nid)->bdata, freepfn, startpfn, endpfn));
 265 }
 266
 267 void __init reserve_bootmem_node (int nid, unsigned long physaddr, unsigned long size)
 268 {
 269         reserve_bootmem_core(NODE_DATA(nid)->bdata, physaddr, size);
 270 }
 271
 272 void __init free_bootmem_node (int nid, unsigned long physaddr, unsigned long size)
 273 {
 274         return(free_bootmem_core(NODE_DATA(nid)->bdata, physaddr, size));
 275 }
 276
 277 unsigned long __init free_all_bootmem_node (int nid)
 278 {
 279         return(free_all_bootmem_core(nid, NODE_DATA(nid)->bdata));
 280 }
 281
 282 unsigned long __init init_bootmem (unsigned long start, unsigned long pages)
 283 {
 284         max_low_pfn = pages;
 285         return(init_bootmem_core(NODE_DATA(0)->bdata, start, 0, pages));
 286 }
 287
 288 void __init reserve_bootmem (unsigned long addr, unsigned long size)
 289 {
 290         reserve_bootmem_core(NODE_DATA(0)->bdata, addr, size);
 291 }
 292
 293 void __init free_bootmem (unsigned long addr, unsigned long size)
 294 {
 295         return(free_bootmem_core(NODE_DATA(0)->bdata, addr, size));
 296 }
 297
 298 unsigned long __init free_all_bootmem (void)
 299 {
 300         return(free_all_bootmem_core(0, NODE_DATA(0)->bdata));
 301 }
 302
 303 void * __init __alloc_bootmem (unsigned long size, unsigned long align, unsigned long goal)
 304 {
 305         /*
 306          * In the discontigmem case, all non-node specific allocations come
 307          * from the first node, node 0.
 308          */
 309         return(__alloc_bootmem_core(NODE_DATA(0)->bdata, size, align, goal));
 310 }
 311
 312 void * __init __alloc_bootmem_node (int nid, unsigned long size, unsigned long align, unsigned long goal)
 313 {
 314         return(__alloc_bootmem_core(NODE_DATA(nid)->bdata, size, align, goal));
 315 }
 316