arch/i386/kernel/e820.c

   1 #include <linux/kernel.h>
   2 #include <linux/types.h>
   3 #include <linux/init.h>
   4 #include <linux/bootmem.h>
   5 #include <linux/ioport.h>
   6 #include <linux/string.h>
   7 #include <linux/kexec.h>
   8 #include <linux/module.h>
   9 #include <linux/mm.h>
  10 #include <linux/efi.h>
  11 #include <linux/pfn.h>
  12 #include <linux/uaccess.h>
  13
  14 #include <asm/pgtable.h>
  15 #include <asm/page.h>
  16 #include <asm/e820.h>
  17
  18 #ifdef CONFIG_XEN
  19 #include <asm/hypervisor.h>
  20 #include <xen/interface/physdev.h>
  21 #include <xen/interface/memory.h>
  22 #include <xen/features.h>
  23 #include <xen/xencons.h>
  24 #endif
  25
  26 #ifdef CONFIG_EFI
  27 int efi_enabled = 0;
  28 EXPORT_SYMBOL(efi_enabled);
  29 #endif
  30
  31 #ifdef CONFIG_XEN
  32 struct e820map machine_e820;
  33 #endif
  34 static void __init
  35 e820_setup_gap(struct e820entry *e820, int nr_map);
  36
  37 struct e820map e820;
  38 struct change_member {
  39         struct e820entry *pbios; /* pointer to original bios entry */
  40         unsigned long long addr; /* address for this change point */
  41 };
  42 static struct change_member change_point_list[2*E820MAX] __initdata;
  43 static struct change_member *change_point[2*E820MAX] __initdata;
  44 static struct e820entry *overlap_list[E820MAX] __initdata;
  45 static struct e820entry new_bios[E820MAX] __initdata;
  46 /* For PCI or other memory-mapped resources */
  47 unsigned long pci_mem_start = 0x10000000;
  48 #ifdef CONFIG_PCI
  49 EXPORT_SYMBOL(pci_mem_start);
  50 #endif
  51 extern int user_defined_memmap;
  52 struct resource data_resource = {
  53         .name   = "Kernel data",
  54         .start  = 0,
  55         .end    = 0,
  56         .flags  = IORESOURCE_BUSY | IORESOURCE_MEM
  57 };
  58
  59 struct resource code_resource = {
  60         .name   = "Kernel code",
  61         .start  = 0,
  62         .end    = 0,
  63         .flags  = IORESOURCE_BUSY | IORESOURCE_MEM
  64 };
  65
  66 static struct resource system_rom_resource = {
  67         .name   = "System ROM",
  68         .start  = 0xf0000,
  69         .end    = 0xfffff,
  70         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  71 };
  72
  73 static struct resource extension_rom_resource = {
  74         .name   = "Extension ROM",
  75         .start  = 0xe0000,
  76         .end    = 0xeffff,
  77         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  78 };
  79
  80 static struct resource adapter_rom_resources[] = { {
  81         .name   = "Adapter ROM",
  82         .start  = 0xc8000,
  83         .end    = 0,
  84         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  85 }, {
  86         .name   = "Adapter ROM",
  87         .start  = 0,
  88         .end    = 0,
  89         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  90 }, {
  91         .name   = "Adapter ROM",
  92         .start  = 0,
  93         .end    = 0,
  94         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
  95 }, {
  96         .name   = "Adapter ROM",
  97         .start  = 0,
  98         .end    = 0,
  99         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
 100 }, {
 101         .name   = "Adapter ROM",
 102         .start  = 0,
 103         .end    = 0,
 104         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
 105 }, {
 106         .name   = "Adapter ROM",
 107         .start  = 0,
 108         .end    = 0,
 109         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
 110 } };
 111
 112 static struct resource video_rom_resource = {
 113         .name   = "Video ROM",
 114         .start  = 0xc0000,
 115         .end    = 0xc7fff,
 116         .flags  = IORESOURCE_BUSY | IORESOURCE_READONLY | IORESOURCE_MEM
 117 };
 118
 119 static struct resource video_ram_resource = {
 120         .name   = "Video RAM area",
 121         .start  = 0xa0000,
 122         .end    = 0xbffff,
 123         .flags  = IORESOURCE_BUSY | IORESOURCE_MEM
 124 };
 125
 126 static struct resource standard_io_resources[] = { {
 127         .name   = "dma1",
 128         .start  = 0x0000,
 129         .end    = 0x001f,
 130         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 131 }, {
 132         .name   = "pic1",
 133         .start  = 0x0020,
 134         .end    = 0x0021,
 135         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 136 }, {
 137         .name   = "timer0",
 138         .start  = 0x0040,
 139         .end    = 0x0043,
 140         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 141 }, {
 142         .name   = "timer1",
 143         .start  = 0x0050,
 144         .end    = 0x0053,
 145         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 146 }, {
 147         .name   = "keyboard",
 148         .start  = 0x0060,
 149         .end    = 0x006f,
 150         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 151 }, {
 152         .name   = "dma page reg",
 153         .start  = 0x0080,
 154         .end    = 0x008f,
 155         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 156 }, {
 157         .name   = "pic2",
 158         .start  = 0x00a0,
 159         .end    = 0x00a1,
 160         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 161 }, {
 162         .name   = "dma2",
 163         .start  = 0x00c0,
 164         .end    = 0x00df,
 165         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 166 }, {
 167         .name   = "fpu",
 168         .start  = 0x00f0,
 169         .end    = 0x00ff,
 170         .flags  = IORESOURCE_BUSY | IORESOURCE_IO
 171 } };
 172
 173 static int romsignature(const unsigned char *x)
 174 {
 175         unsigned short sig;
 176         int ret = 0;
 177         if (probe_kernel_address((const unsigned short *)x, sig) == 0)
 178                 ret = (sig == 0xaa55);
 179         return ret;
 180 }
 181
 182 static int __init romchecksum(unsigned char *rom, unsigned long length)
 183 {
 184         unsigned char *p, sum = 0;
 185
 186         for (p = rom; p < rom + length; p++)
 187                 sum += *p;
 188         return sum == 0;
 189 }
 190
 191 static void __init probe_roms(void)
 192 {
 193         unsigned long start, length, upper;
 194         unsigned char *rom;
 195         int           i;
 196
 197 #ifdef CONFIG_XEN
 198         /* Nothing to do if not running in dom0. */
 199         if (!is_initial_xendomain())
 200                 return;
 201 #endif
 202
 203         /* video rom */
 204         upper = adapter_rom_resources[0].start;
 205         for (start = video_rom_resource.start; start < upper; start += 2048) {
 206                 rom = isa_bus_to_virt(start);
 207                 if (!romsignature(rom))
 208                         continue;
 209
 210                 video_rom_resource.start = start;
 211
 212                 /* 0 < length <= 0x7f * 512, historically */
 213                 length = rom[2] * 512;
 214
 215                 /* if checksum okay, trust length byte */
 216                 if (length && romchecksum(rom, length))
 217                         video_rom_resource.end = start + length - 1;
 218
 219                 request_resource(&iomem_resource, &video_rom_resource);
 220                 break;
 221         }
 222
 223         start = (video_rom_resource.end + 1 + 2047) & ~2047UL;
 224         if (start < upper)
 225                 start = upper;
 226
 227         /* system rom */
 228         request_resource(&iomem_resource, &system_rom_resource);
 229         upper = system_rom_resource.start;
 230
 231         /* check for extension rom (ignore length byte!) */
 232         rom = isa_bus_to_virt(extension_rom_resource.start);
 233         if (romsignature(rom)) {
 234                 length = extension_rom_resource.end - extension_rom_resource.start + 1;
 235                 if (romchecksum(rom, length)) {
 236                         request_resource(&iomem_resource, &extension_rom_resource);
 237                         upper = extension_rom_resource.start;
 238                 }
 239         }
 240
 241         /* check for adapter roms on 2k boundaries */
 242         for (i = 0; i < ARRAY_SIZE(adapter_rom_resources) && start < upper; start += 2048) {
 243                 rom = isa_bus_to_virt(start);
 244                 if (!romsignature(rom))
 245                         continue;
 246
 247                 /* 0 < length <= 0x7f * 512, historically */
 248                 length = rom[2] * 512;
 249
 250                 /* but accept any length that fits if checksum okay */
 251                 if (!length || start + length > upper || !romchecksum(rom, length))
 252                         continue;
 253
 254                 adapter_rom_resources[i].start = start;
 255                 adapter_rom_resources[i].end = start + length - 1;
 256                 request_resource(&iomem_resource, &adapter_rom_resources[i]);
 257
 258                 start = adapter_rom_resources[i++].end & ~2047UL;
 259         }
 260 }
 261
 262 /*
 263  * Request address space for all standard RAM and ROM resources
 264  * and also for regions reported as reserved by the e820.
 265  */
 266 static void __init
 267 legacy_init_iomem_resources(struct resource *code_resource, struct resource *data_resource)
 268 {
 269         int i;
 270         struct e820entry *map = e820.map;
 271         int nr_map = e820.nr_map;
 272 #ifdef CONFIG_XEN_PRIVILEGED_GUEST
 273         struct xen_memory_map memmap;
 274
 275         map = machine_e820.map;
 276         memmap.nr_entries = E820MAX;
 277
 278         set_xen_guest_handle(memmap.buffer, map);
 279
 280         if(HYPERVISOR_memory_op(XENMEM_machine_memory_map, &memmap))
 281                 BUG();
 282         machine_e820.nr_map = memmap.nr_entries;
 283         nr_map = memmap.nr_entries;
 284         e820_setup_gap(map, memmap.nr_entries);
 285 #endif
 286
 287         probe_roms();
 288         for (i = 0; i < nr_map; i++) {
 289                 struct resource *res;
 290 #ifndef CONFIG_RESOURCES_64BIT
 291                 if (map[i].addr + map[i].size > 0x100000000ULL)
 292                         continue;
 293 #endif
 294                 res = kzalloc(sizeof(struct resource), GFP_ATOMIC);
 295                 switch (map[i].type) {
 296                 case E820_RAM:  res->name = "System RAM"; break;
 297                 case E820_ACPI: res->name = "ACPI Tables"; break;
 298                 case E820_NVS:  res->name = "ACPI Non-volatile Storage"; break;
 299                 default:        res->name = "reserved";
 300                 }
 301                 res->start = map[i].addr;
 302                 res->end = res->start + map[i].size - 1;
 303                 res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
 304                 if (request_resource(&iomem_resource, res)) {
 305                         kfree(res);
 306                         continue;
 307                 }
 308                 if (map[i].type == E820_RAM) {
 309                         /*
 310                          *  We don't know which RAM region contains kernel data,
 311                          *  so we try it repeatedly and let the resource manager
 312                          *  test it.
 313                          */
 314 #ifndef CONFIG_XEN
 315                         request_resource(res, code_resource);
 316                         request_resource(res, data_resource);
 317 #endif
 318 #ifdef CONFIG_KEXEC
 319                         request_resource(res, &crashk_res);
 320 #endif
 321                 }
 322         }
 323 }
 324
 325 /*
 326  * Request address space for all standard resources
 327  *
 328  * This is called just before pcibios_init(), which is also a
 329  * subsys_initcall, but is linked in later (in arch/i386/pci/common.c).
 330  */
 331 static int __init request_standard_resources(void)
 332 {
 333         int i;
 334
 335         printk("Setting up standard PCI resources\n");
 336 #ifdef CONFIG_XEN
 337         /* Nothing to do if not running in dom0. */
 338         if (!is_initial_xendomain())
 339                 return 0;
 340 #endif
 341         if (efi_enabled)
 342                 efi_initialize_iomem_resources(&code_resource, &data_resource);
 343         else
 344                 legacy_init_iomem_resources(&code_resource, &data_resource);
 345
 346         /* EFI systems may still have VGA */
 347         request_resource(&iomem_resource, &video_ram_resource);
 348
 349         /* request I/O space for devices used on all i[345]86 PCs */
 350         for (i = 0; i < ARRAY_SIZE(standard_io_resources); i++)
 351                 request_resource(&ioport_resource, &standard_io_resources[i]);
 352         return 0;
 353 }
 354
 355 subsys_initcall(request_standard_resources);
 356
 357 void __init add_memory_region(unsigned long long start,
 358                               unsigned long long size, int type)
 359 {
 360         int x;
 361
 362         if (!efi_enabled) {
 363                 x = e820.nr_map;
 364
 365                 if (x == E820MAX) {
 366                     printk(KERN_ERR "Ooops! Too many entries in the memory map!\n");
 367                     return;
 368                 }
 369
 370                 e820.map[x].addr = start;
 371                 e820.map[x].size = size;
 372                 e820.map[x].type = type;
 373                 e820.nr_map++;
 374         }
 375 } /* add_memory_region */
 376
 377 /*
 378  * Sanitize the BIOS e820 map.
 379  *
 380  * Some e820 responses include overlapping entries.  The following
 381  * replaces the original e820 map with a new one, removing overlaps.
 382  *
 383  */
 384 int __init sanitize_e820_map(struct e820entry * biosmap, char * pnr_map)
 385 {
 386         struct change_member *change_tmp;
 387         unsigned long current_type, last_type;
 388         unsigned long long last_addr;
 389         int chgidx, still_changing;
 390         int overlap_entries;
 391         int new_bios_entry;
 392         int old_nr, new_nr, chg_nr;
 393         int i;
 394
 395         /*
 396                 Visually we're performing the following (1,2,3,4 = memory types)...
 397
 398                 Sample memory map (w/overlaps):
 399                    ____22__________________
 400                    ______________________4_
 401                    ____1111________________
 402                    _44_____________________
 403                    11111111________________
 404                    ____________________33__
 405                    ___________44___________
 406                    __________33333_________
 407                    ______________22________
 408                    ___________________2222_
 409                    _________111111111______
 410                    _____________________11_
 411                    _________________4______
 412
 413                 Sanitized equivalent (no overlap):
 414                    1_______________________
 415                    _44_____________________
 416                    ___1____________________
 417                    ____22__________________
 418                    ______11________________
 419                    _________1______________
 420                    __________3_____________
 421                    ___________44___________
 422                    _____________33_________
 423                    _______________2________
 424                    ________________1_______
 425                    _________________4______
 426                    ___________________2____
 427                    ____________________33__
 428                    ______________________4_
 429         */
 430         printk("sanitize start\n");
 431         /* if there's only one memory region, don't bother */
 432         if (*pnr_map < 2) {
 433                 printk("sanitize bail 0\n");
 434                 return -1;
 435         }
 436
 437         old_nr = *pnr_map;
 438
 439         /* bail out if we find any unreasonable addresses in bios map */
 440         for (i=0; i<old_nr; i++)
 441                 if (biosmap[i].addr + biosmap[i].size < biosmap[i].addr) {
 442                         printk("sanitize bail 1\n");
 443                         return -1;
 444                 }
 445
 446         /* create pointers for initial change-point information (for sorting) */
 447         for (i=0; i < 2*old_nr; i++)
 448                 change_point[i] = &change_point_list[i];
 449
 450         /* record all known change-points (starting and ending addresses),
 451            omitting those that are for empty memory regions */
 452         chgidx = 0;
 453         for (i=0; i < old_nr; i++)      {
 454                 if (biosmap[i].size != 0) {
 455                         change_point[chgidx]->addr = biosmap[i].addr;
 456                         change_point[chgidx++]->pbios = &biosmap[i];
 457                         change_point[chgidx]->addr = biosmap[i].addr + biosmap[i].size;
 458                         change_point[chgidx++]->pbios = &biosmap[i];
 459                 }
 460         }
 461         chg_nr = chgidx;        /* true number of change-points */
 462
 463         /* sort change-point list by memory addresses (low -> high) */
 464         still_changing = 1;
 465         while (still_changing)  {
 466                 still_changing = 0;
 467                 for (i=1; i < chg_nr; i++)  {
 468                         /* if <current_addr> > <last_addr>, swap */
 469                         /* or, if current=<start_addr> & last=<end_addr>, swap */
 470                         if ((change_point[i]->addr < change_point[i-1]->addr) ||
 471                                 ((change_point[i]->addr == change_point[i-1]->addr) &&
 472                                  (change_point[i]->addr == change_point[i]->pbios->addr) &&
 473                                  (change_point[i-1]->addr != change_point[i-1]->pbios->addr))
 474                            )
 475                         {
 476                                 change_tmp = change_point[i];
 477                                 change_point[i] = change_point[i-1];
 478                                 change_point[i-1] = change_tmp;
 479                                 still_changing=1;
 480                         }
 481                 }
 482         }
 483
 484         /* create a new bios memory map, removing overlaps */
 485         overlap_entries=0;       /* number of entries in the overlap table */
 486         new_bios_entry=0;        /* index for creating new bios map entries */
 487         last_type = 0;           /* start with undefined memory type */
 488         last_addr = 0;           /* start with 0 as last starting address */
 489         /* loop through change-points, determining affect on the new bios map */
 490         for (chgidx=0; chgidx < chg_nr; chgidx++)
 491         {
 492                 /* keep track of all overlapping bios entries */
 493                 if (change_point[chgidx]->addr == change_point[chgidx]->pbios->addr)
 494                 {
 495                         /* add map entry to overlap list (> 1 entry implies an overlap) */
 496                         overlap_list[overlap_entries++]=change_point[chgidx]->pbios;
 497                 }
 498                 else
 499                 {
 500                         /* remove entry from list (order independent, so swap with last) */
 501                         for (i=0; i<overlap_entries; i++)
 502                         {
 503                                 if (overlap_list[i] == change_point[chgidx]->pbios)
 504                                         overlap_list[i] = overlap_list[overlap_entries-1];
 505                         }
 506                         overlap_entries--;
 507                 }
 508                 /* if there are overlapping entries, decide which "type" to use */
 509                 /* (larger value takes precedence -- 1=usable, 2,3,4,4+=unusable) */
 510                 current_type = 0;
 511                 for (i=0; i<overlap_entries; i++)
 512                         if (overlap_list[i]->type > current_type)
 513                                 current_type = overlap_list[i]->type;
 514                 /* continue building up new bios map based on this information */
 515                 if (current_type != last_type)  {
 516                         if (last_type != 0)      {
 517                                 new_bios[new_bios_entry].size =
 518                                         change_point[chgidx]->addr - last_addr;
 519                                 /* move forward only if the new size was non-zero */
 520                                 if (new_bios[new_bios_entry].size != 0)
 521                                         if (++new_bios_entry >= E820MAX)
 522                                                 break;  /* no more space left for new bios entries */
 523                         }
 524                         if (current_type != 0)  {
 525                                 new_bios[new_bios_entry].addr = change_point[chgidx]->addr;
 526                                 new_bios[new_bios_entry].type = current_type;
 527                                 last_addr=change_point[chgidx]->addr;
 528                         }
 529                         last_type = current_type;
 530                 }
 531         }
 532         new_nr = new_bios_entry;   /* retain count for new bios entries */
 533
 534         /* copy new bios mapping into original location */
 535         memcpy(biosmap, new_bios, new_nr*sizeof(struct e820entry));
 536         *pnr_map = new_nr;
 537
 538         printk("sanitize end\n");
 539         return 0;
 540 }
 541
 542 /*
 543  * Copy the BIOS e820 map into a safe place.
 544  *
 545  * Sanity-check it while we're at it..
 546  *
 547  * If we're lucky and live on a modern system, the setup code
 548  * will have given us a memory map that we can use to properly
 549  * set up memory.  If we aren't, we'll fake a memory map.
 550  *
 551  * We check to see that the memory map contains at least 2 elements
 552  * before we'll use it, because the detection code in setup.S may
 553  * not be perfect and most every PC known to man has two memory
 554  * regions: one from 0 to 640k, and one from 1mb up.  (The IBM
 555  * thinkpad 560x, for example, does not cooperate with the memory
 556  * detection code.)
 557  */
 558 int __init copy_e820_map(struct e820entry * biosmap, int nr_map)
 559 {
 560 #ifndef CONFIG_XEN
 561         /* Only one memory region (or negative)? Ignore it */
 562         if (nr_map < 2)
 563                 return -1;
 564 #else
 565         BUG_ON(nr_map < 1);
 566 #endif
 567         do {
 568                 unsigned long long start = biosmap->addr;
 569                 unsigned long long size = biosmap->size;
 570                 unsigned long long end = start + size;
 571                 unsigned long type = biosmap->type;
 572                 printk("copy_e820_map() start: %016Lx size: %016Lx end: %016Lx type: %ld\n", start, size, end, type);
 573
 574                 /* Overflow in 64 bits? Ignore the memory map. */
 575                 if (start > end)
 576                         return -1;
 577
 578 #ifndef CONFIG_XEN
 579                 /*
 580                  * Some BIOSes claim RAM in the 640k - 1M region.
 581                  * Not right. Fix it up.
 582                  */
 583                 if (type == E820_RAM) {
 584                         printk("copy_e820_map() type is E820_RAM\n");
 585                         if (start < 0x100000ULL && end > 0xA0000ULL) {
 586                                 printk("copy_e820_map() lies in range...\n");
 587                                 if (start < 0xA0000ULL) {
 588                                         printk("copy_e820_map() start < 0xA0000ULL\n");
 589                                         add_memory_region(start, 0xA0000ULL-start, type);
 590                                 }
 591                                 if (end <= 0x100000ULL) {
 592                                         printk("copy_e820_map() end <= 0x100000ULL\n");
 593                                         continue;
 594                                 }
 595                                 start = 0x100000ULL;
 596                                 size = end - start;
 597                         }
 598                 }
 599 #endif
 600                 add_memory_region(start, size, type);
 601         } while (biosmap++,--nr_map);
 602         return 0;
 603 }
 604
 605 /*
 606  * Callback for efi_memory_walk.
 607  */
 608 static int __init
 609 efi_find_max_pfn(unsigned long start, unsigned long end, void *arg)
 610 {
 611         unsigned long *max_pfn = arg, pfn;
 612
 613         if (start < end) {
 614                 pfn = PFN_UP(end -1);
 615                 if (pfn > *max_pfn)
 616                         *max_pfn = pfn;
 617         }
 618         return 0;
 619 }
 620
 621 static int __init
 622 efi_memory_present_wrapper(unsigned long start, unsigned long end, void *arg)
 623 {
 624         memory_present(0, PFN_UP(start), PFN_DOWN(end));
 625         return 0;
 626 }
 627
 628 /*
 629  * Find the highest page frame number we have available
 630  */
 631 void __init find_max_pfn(void)
 632 {
 633         int i;
 634
 635         max_pfn = 0;
 636         if (efi_enabled) {
 637                 efi_memmap_walk(efi_find_max_pfn, &max_pfn);
 638                 efi_memmap_walk(efi_memory_present_wrapper, NULL);
 639                 return;
 640         }
 641
 642         for (i = 0; i < e820.nr_map; i++) {
 643                 unsigned long start, end;
 644                 /* RAM? */
 645                 if (e820.map[i].type != E820_RAM)
 646                         continue;
 647                 start = PFN_UP(e820.map[i].addr);
 648                 end = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
 649                 if (start >= end)
 650                         continue;
 651                 if (end > max_pfn)
 652                         max_pfn = end;
 653                 memory_present(0, start, end);
 654         }
 655 }
 656
 657 /*
 658  * Free all available memory for boot time allocation.  Used
 659  * as a callback function by efi_memory_walk()
 660  */
 661
 662 static int __init
 663 free_available_memory(unsigned long start, unsigned long end, void *arg)
 664 {
 665         /* check max_low_pfn */
 666         if (start >= (max_low_pfn << PAGE_SHIFT))
 667                 return 0;
 668         if (end >= (max_low_pfn << PAGE_SHIFT))
 669                 end = max_low_pfn << PAGE_SHIFT;
 670         if (start < end)
 671                 free_bootmem(start, end - start);
 672
 673         return 0;
 674 }
 675 /*
 676  * Register fully available low RAM pages with the bootmem allocator.
 677  */
 678 void __init register_bootmem_low_pages(unsigned long max_low_pfn)
 679 {
 680         int i;
 681
 682         if (efi_enabled) {
 683                 efi_memmap_walk(free_available_memory, NULL);
 684                 return;
 685         }
 686         for (i = 0; i < e820.nr_map; i++) {
 687                 unsigned long curr_pfn, last_pfn, size;
 688                 /*
 689                  * Reserve usable low memory
 690                  */
 691                 if (e820.map[i].type != E820_RAM)
 692                         continue;
 693                 /*
 694                  * We are rounding up the start address of usable memory:
 695                  */
 696                 curr_pfn = PFN_UP(e820.map[i].addr);
 697                 if (curr_pfn >= max_low_pfn)
 698                         continue;
 699                 /*
 700                  * ... and at the end of the usable range downwards:
 701                  */
 702                 last_pfn = PFN_DOWN(e820.map[i].addr + e820.map[i].size);
 703
 704 #ifdef CONFIG_XEN
 705                 /*
 706                  * Truncate to the number of actual pages currently
 707                  * present.
 708                  */
 709                 if (last_pfn > xen_start_info->nr_pages)
 710                         last_pfn = xen_start_info->nr_pages;
 711 #endif
 712
 713                 if (last_pfn > max_low_pfn)
 714                         last_pfn = max_low_pfn;
 715
 716                 /*
 717                  * .. finally, did all the rounding and playing
 718                  * around just make the area go away?
 719                  */
 720                 if (last_pfn <= curr_pfn)
 721                         continue;
 722
 723                 size = last_pfn - curr_pfn;
 724                 free_bootmem(PFN_PHYS(curr_pfn), PFN_PHYS(size));
 725         }
 726 }
 727
 728 /*
 729  * Locate a unused range of the physical address space below 4G which
 730  * can be used for PCI mappings.
 731  */
 732 static void __init
 733 e820_setup_gap(struct e820entry *e820, int nr_map)
 734 {
 735         unsigned long gapstart, gapsize, round;
 736         unsigned long long last;
 737         int i;
 738
 739         /*
 740          * Search for the bigest gap in the low 32 bits of the e820
 741          * memory space.
 742          */
 743         last = 0x100000000ull;
 744         gapstart = 0x10000000;
 745         gapsize = 0x400000;
 746         i = nr_map;
 747         while (--i >= 0) {
 748                 unsigned long long start = e820[i].addr;
 749                 unsigned long long end = start + e820[i].size;
 750
 751                 /*
 752                  * Since "last" is at most 4GB, we know we'll
 753                  * fit in 32 bits if this condition is true
 754                  */
 755                 if (last > end) {
 756                         unsigned long gap = last - end;
 757
 758                         if (gap > gapsize) {
 759                                 gapsize = gap;
 760                                 gapstart = end;
 761                         }
 762                 }
 763                 if (start < last)
 764                         last = start;
 765         }
 766
 767         /*
 768          * See how much we want to round up: start off with
 769          * rounding to the next 1MB area.
 770          */
 771         round = 0x100000;
 772         while ((gapsize >> 4) > round)
 773                 round += round;
 774         /* Fun with two's complement */
 775         pci_mem_start = (gapstart + round) & -round;
 776
 777         printk("Allocating PCI resources starting at %08lx (gap: %08lx:%08lx)\n",
 778                 pci_mem_start, gapstart, gapsize);
 779 }
 780
 781 void __init e820_register_memory(void)
 782 {
 783 #ifndef CONFIG_XEN
 784         e820_setup_gap(e820.map, e820.nr_map);
 785 #endif
 786 }
 787
 788 void __init print_memory_map(char *who)
 789 {
 790         int i;
 791
 792         for (i = 0; i < e820.nr_map; i++) {
 793                 printk(" %s: %016Lx - %016Lx ", who,
 794                         e820.map[i].addr,
 795                         e820.map[i].addr + e820.map[i].size);
 796                 switch (e820.map[i].type) {
 797                 case E820_RAM:  printk("(usable)\n");
 798                                 break;
 799                 case E820_RESERVED:
 800                                 printk("(reserved)\n");
 801                                 break;
 802                 case E820_ACPI:
 803                                 printk("(ACPI data)\n");
 804                                 break;
 805                 case E820_NVS:
 806                                 printk("(ACPI NVS)\n");
 807                                 break;
 808                 default:        printk("type %lu\n", e820.map[i].type);
 809                                 break;
 810                 }
 811         }
 812 }
 813
 814 static __init __always_inline void efi_limit_regions(unsigned long long size)
 815 {
 816         unsigned long long current_addr = 0;
 817         efi_memory_desc_t *md, *next_md;
 818         void *p, *p1;
 819         int i, j;
 820
 821         j = 0;
 822         p1 = memmap.map;
 823         for (p = p1, i = 0; p < memmap.map_end; p += memmap.desc_size, i++) {
 824                 md = p;
 825                 next_md = p1;
 826                 current_addr = md->phys_addr +
 827                         PFN_PHYS(md->num_pages);
 828                 if (is_available_memory(md)) {
 829                         if (md->phys_addr >= size) continue;
 830                         memcpy(next_md, md, memmap.desc_size);
 831                         if (current_addr >= size) {
 832                                 next_md->num_pages -=
 833                                         PFN_UP(current_addr-size);
 834                         }
 835                         p1 += memmap.desc_size;
 836                         next_md = p1;
 837                         j++;
 838                 } else if ((md->attribute & EFI_MEMORY_RUNTIME) ==
 839                            EFI_MEMORY_RUNTIME) {
 840                         /* In order to make runtime services
 841                          * available we have to include runtime
 842                          * memory regions in memory map */
 843                         memcpy(next_md, md, memmap.desc_size);
 844                         p1 += memmap.desc_size;
 845                         next_md = p1;
 846                         j++;
 847                 }
 848         }
 849         memmap.nr_map = j;
 850         memmap.map_end = memmap.map +
 851                 (memmap.nr_map * memmap.desc_size);
 852 }
 853
 854 void __init limit_regions(unsigned long long size)
 855 {
 856         unsigned long long current_addr = 0;
 857         int i;
 858
 859         print_memory_map("limit_regions start");
 860         if (efi_enabled) {
 861                 efi_limit_regions(size);
 862                 return;
 863         }
 864         for (i = 0; i < e820.nr_map; i++) {
 865                 current_addr = e820.map[i].addr + e820.map[i].size;
 866                 if (current_addr < size)
 867                         continue;
 868
 869                 if (e820.map[i].type != E820_RAM)
 870                         continue;
 871
 872                 if (e820.map[i].addr >= size) {
 873                         /*
 874                          * This region starts past the end of the
 875                          * requested size, skip it completely.
 876                          */
 877                         e820.nr_map = i;
 878                 } else {
 879                         e820.nr_map = i + 1;
 880                         e820.map[i].size -= current_addr - size;
 881                 }
 882                 print_memory_map("limit_regions endfor");
 883                 return;
 884         }
 885 #ifdef CONFIG_XEN
 886         if (i==e820.nr_map && current_addr < size) {
 887                 /*
 888                  * The e820 map finished before our requested size so
 889                  * extend the final entry to the requested address.
 890                  */
 891                 --i;
 892                 if (e820.map[i].type == E820_RAM)
 893                         e820.map[i].size -= current_addr - size;
 894                 else
 895                         add_memory_region(current_addr, size - current_addr, E820_RAM);
 896         }
 897 #endif
 898         print_memory_map("limit_regions endfunc");
 899 }
 900
 901  /*
 902   * This function checks if the entire range <start,end> is mapped with type.
 903   *
 904   * Note: this function only works correct if the e820 table is sorted and
 905   * not-overlapping, which is the case
 906   */
 907 int __init
 908 e820_all_mapped(unsigned long s, unsigned long e, unsigned type)
 909 {
 910         u64 start = s;
 911         u64 end = e;
 912         int i;
 913         for (i = 0; i < e820.nr_map; i++) {
 914                 struct e820entry *ei = &e820.map[i];
 915                 if (type && ei->type != type)
 916                         continue;
 917                 /* is the region (part) in overlap with the current region ?*/
 918                 if (ei->addr >= end || ei->addr + ei->size <= start)
 919                         continue;
 920                 /* if the region is at the beginning of <start,end> we move
 921                  * start to the end of the region since it's ok until there
 922                  */
 923                 if (ei->addr <= start)
 924                         start = ei->addr + ei->size;
 925                 /* if start is now at or beyond end, we're done, full
 926                  * coverage */
 927                 if (start >= end)
 928                         return 1; /* we're done */
 929         }
 930         return 0;
 931 }
 932
 933 static int __init parse_memmap(char *arg)
 934 {
 935         if (!arg)
 936                 return -EINVAL;
 937
 938         if (strcmp(arg, "exactmap") == 0) {
 939 #ifdef CONFIG_CRASH_DUMP
 940                 /* If we are doing a crash dump, we
 941                  * still need to know the real mem
 942                  * size before original memory map is
 943                  * reset.
 944                  */
 945                 find_max_pfn();
 946                 saved_max_pfn = max_pfn;
 947 #endif
 948                 e820.nr_map = 0;
 949                 user_defined_memmap = 1;
 950         } else {
 951                 /* If the user specifies memory size, we
 952                  * limit the BIOS-provided memory map to
 953                  * that size. exactmap can be used to specify
 954                  * the exact map. mem=number can be used to
 955                  * trim the existing memory map.
 956                  */
 957                 unsigned long long start_at, mem_size;
 958
 959                 mem_size = memparse(arg, &arg);
 960                 if (*arg == '@') {
 961                         start_at = memparse(arg+1, &arg);
 962                         add_memory_region(start_at, mem_size, E820_RAM);
 963                 } else if (*arg == '#') {
 964                         start_at = memparse(arg+1, &arg);
 965                         add_memory_region(start_at, mem_size, E820_ACPI);
 966                 } else if (*arg == '$') {
 967                         start_at = memparse(arg+1, &arg);
 968                         add_memory_region(start_at, mem_size, E820_RESERVED);
 969                 } else {
 970                         limit_regions(mem_size);
 971                         user_defined_memmap = 1;
 972                 }
 973         }
 974         return 0;
 975 }
 976 early_param("memmap", parse_memmap);