arch/ia64/mm/init.c

   1 /*
   2  * Initialize MMU support.
   3  *
   4  * Copyright (C) 1998-2003 Hewlett-Packard Co
   5  *      David Mosberger-Tang <davidm@hpl.hp.com>
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/init.h>
   9
  10 #include <linux/bootmem.h>
  11 #include <linux/efi.h>
  12 #include <linux/elf.h>
  13 #include <linux/mm.h>
  14 #include <linux/mmzone.h>
  15 #include <linux/module.h>
  16 #include <linux/personality.h>
  17 #include <linux/reboot.h>
  18 #include <linux/slab.h>
  19 #include <linux/swap.h>
  20 #include <linux/proc_fs.h>
  21 #include <linux/bitops.h>
  22
  23 #include <asm/a.out.h>
  24 #include <asm/dma.h>
  25 #include <asm/ia32.h>
  26 #include <asm/io.h>
  27 #include <asm/machvec.h>
  28 #include <asm/numa.h>
  29 #include <asm/patch.h>
  30 #include <asm/pgalloc.h>
  31 #include <asm/sal.h>
  32 #include <asm/sections.h>
  33 #include <asm/system.h>
  34 #include <asm/tlb.h>
  35 #include <asm/uaccess.h>
  36 #include <asm/unistd.h>
  37 #include <asm/mca.h>
  38
  39 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  40
  41 DEFINE_PER_CPU(unsigned long *, __pgtable_quicklist);
  42 DEFINE_PER_CPU(long, __pgtable_quicklist_size);
  43
  44 extern void ia64_tlb_init (void);
  45
  46 unsigned long MAX_DMA_ADDRESS = PAGE_OFFSET + 0x100000000UL;
  47
  48 #ifdef CONFIG_VIRTUAL_MEM_MAP
  49 unsigned long vmalloc_end = VMALLOC_END_INIT;
  50 EXPORT_SYMBOL(vmalloc_end);
  51 struct page *vmem_map;
  52 EXPORT_SYMBOL(vmem_map);
  53 #endif
  54
  55 struct page *zero_page_memmap_ptr;      /* map entry for zero page */
  56 EXPORT_SYMBOL(zero_page_memmap_ptr);
  57
  58 #define MIN_PGT_PAGES                   25UL
  59 #define MAX_PGT_FREES_PER_PASS          16L
  60 #define PGT_FRACTION_OF_NODE_MEM        16
  61
  62 static inline long
  63 max_pgt_pages(void)
  64 {
  65         u64 node_free_pages, max_pgt_pages;
  66
  67 #ifndef CONFIG_NUMA
  68         node_free_pages = nr_free_pages();
  69 #else
  70         node_free_pages = nr_free_pages_pgdat(NODE_DATA(numa_node_id()));
  71 #endif
  72         max_pgt_pages = node_free_pages / PGT_FRACTION_OF_NODE_MEM;
  73         max_pgt_pages = max(max_pgt_pages, MIN_PGT_PAGES);
  74         return max_pgt_pages;
  75 }
  76
  77 static inline long
  78 min_pages_to_free(void)
  79 {
  80         long pages_to_free;
  81
  82         pages_to_free = pgtable_quicklist_size - max_pgt_pages();
  83         pages_to_free = min(pages_to_free, MAX_PGT_FREES_PER_PASS);
  84         return pages_to_free;
  85 }
  86
  87 void
  88 check_pgt_cache(void)
  89 {
  90         long pages_to_free;
  91
  92         if (unlikely(pgtable_quicklist_size <= MIN_PGT_PAGES))
  93                 return;
  94
  95         preempt_disable();
  96         while (unlikely((pages_to_free = min_pages_to_free()) > 0)) {
  97                 while (pages_to_free--) {
  98                         free_page((unsigned long)pgtable_quicklist_alloc());
  99                 }
 100                 preempt_enable();
 101                 preempt_disable();
 102         }
 103         preempt_enable();
 104 }
 105
 106 void
 107 lazy_mmu_prot_update (pte_t pte)
 108 {
 109         unsigned long addr;
 110         struct page *page;
 111         unsigned long order;
 112
 113         if (!pte_exec(pte))
 114                 return;                         /* not an executable page... */
 115
 116         page = pte_page(pte);
 117         addr = (unsigned long) page_address(page);
 118
 119         if (test_bit(PG_arch_1, &page->flags))
 120                 return;                         /* i-cache is already coherent with d-cache */
 121
 122         if (PageCompound(page)) {
 123                 order = (unsigned long) (page[1].lru.prev);
 124                 flush_icache_range(addr, addr + (1UL << order << PAGE_SHIFT));
 125         }
 126         else
 127                 flush_icache_range(addr, addr + PAGE_SIZE);
 128         set_bit(PG_arch_1, &page->flags);       /* mark page as clean */
 129 }
 130
 131 inline void
 132 ia64_set_rbs_bot (void)
 133 {
 134         unsigned long stack_size = current->signal->rlim[RLIMIT_STACK].rlim_max & -16;
 135
 136         if (stack_size > MAX_USER_STACK_SIZE)
 137                 stack_size = MAX_USER_STACK_SIZE;
 138         current->thread.rbs_bot = STACK_TOP - stack_size;
 139 }
 140
 141 /*
 142  * This performs some platform-dependent address space initialization.
 143  * On IA-64, we want to setup the VM area for the register backing
 144  * store (which grows upwards) and install the gateway page which is
 145  * used for signal trampolines, etc.
 146  */
 147 void
 148 ia64_init_addr_space (void)
 149 {
 150         struct vm_area_struct *vma;
 151
 152         ia64_set_rbs_bot();
 153
 154         /*
 155          * If we're out of memory and kmem_cache_alloc() returns NULL, we simply ignore
 156          * the problem.  When the process attempts to write to the register backing store
 157          * for the first time, it will get a SEGFAULT in this case.
 158          */
 159         vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
 160         if (vma) {
 161                 memset(vma, 0, sizeof(*vma));
 162                 vma->vm_mm = current->mm;
 163                 vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
 164                 vma->vm_end = vma->vm_start + PAGE_SIZE;
 165                 vma->vm_page_prot = protection_map[VM_DATA_DEFAULT_FLAGS & 0x7];
 166                 vma->vm_flags = VM_DATA_DEFAULT_FLAGS|VM_GROWSUP|VM_ACCOUNT;
 167                 down_write(&current->mm->mmap_sem);
 168                 if (insert_vm_struct(current->mm, vma)) {
 169                         up_write(&current->mm->mmap_sem);
 170                         kmem_cache_free(vm_area_cachep, vma);
 171                         return;
 172                 }
 173                 up_write(&current->mm->mmap_sem);
 174         }
 175
 176         /* map NaT-page at address zero to speed up speculative dereferencing of NULL: */
 177         if (!(current->personality & MMAP_PAGE_ZERO)) {
 178                 vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
 179                 if (vma) {
 180                         memset(vma, 0, sizeof(*vma));
 181                         vma->vm_mm = current->mm;
 182                         vma->vm_end = PAGE_SIZE;
 183                         vma->vm_page_prot = __pgprot(pgprot_val(PAGE_READONLY) | _PAGE_MA_NAT);
 184                         vma->vm_flags = VM_READ | VM_MAYREAD | VM_IO | VM_RESERVED;
 185                         down_write(&current->mm->mmap_sem);
 186                         if (insert_vm_struct(current->mm, vma)) {
 187                                 up_write(&current->mm->mmap_sem);
 188                                 kmem_cache_free(vm_area_cachep, vma);
 189                                 return;
 190                         }
 191                         up_write(&current->mm->mmap_sem);
 192                 }
 193         }
 194 }
 195
 196 void
 197 free_initmem (void)
 198 {
 199         unsigned long addr, eaddr;
 200
 201         addr = (unsigned long) ia64_imva(__init_begin);
 202         eaddr = (unsigned long) ia64_imva(__init_end);
 203         while (addr < eaddr) {
 204                 ClearPageReserved(virt_to_page(addr));
 205                 init_page_count(virt_to_page(addr));
 206                 free_page(addr);
 207                 ++totalram_pages;
 208                 addr += PAGE_SIZE;
 209         }
 210         printk(KERN_INFO "Freeing unused kernel memory: %ldkB freed\n",
 211                (__init_end - __init_begin) >> 10);
 212 }
 213
 214 void __init
 215 free_initrd_mem (unsigned long start, unsigned long end)
 216 {
 217         struct page *page;
 218         /*
 219          * EFI uses 4KB pages while the kernel can use 4KB or bigger.
 220          * Thus EFI and the kernel may have different page sizes. It is
 221          * therefore possible to have the initrd share the same page as
 222          * the end of the kernel (given current setup).
 223          *
 224          * To avoid freeing/using the wrong page (kernel sized) we:
 225          *      - align up the beginning of initrd
 226          *      - align down the end of initrd
 227          *
 228          *  |             |
 229          *  |=============| a000
 230          *  |             |
 231          *  |             |
 232          *  |             | 9000
 233          *  |/////////////|
 234          *  |/////////////|
 235          *  |=============| 8000
 236          *  |///INITRD////|
 237          *  |/////////////|
 238          *  |/////////////| 7000
 239          *  |             |
 240          *  |KKKKKKKKKKKKK|
 241          *  |=============| 6000
 242          *  |KKKKKKKKKKKKK|
 243          *  |KKKKKKKKKKKKK|
 244          *  K=kernel using 8KB pages
 245          *
 246          * In this example, we must free page 8000 ONLY. So we must align up
 247          * initrd_start and keep initrd_end as is.
 248          */
 249         start = PAGE_ALIGN(start);
 250         end = end & PAGE_MASK;
 251
 252         if (start < end)
 253                 printk(KERN_INFO "Freeing initrd memory: %ldkB freed\n", (end - start) >> 10);
 254
 255         for (; start < end; start += PAGE_SIZE) {
 256                 if (!virt_addr_valid(start))
 257                         continue;
 258                 page = virt_to_page(start);
 259                 ClearPageReserved(page);
 260                 init_page_count(page);
 261                 free_page(start);
 262                 ++totalram_pages;
 263         }
 264 }
 265
 266 /*
 267  * This installs a clean page in the kernel's page table.
 268  */
 269 static struct page * __init
 270 put_kernel_page (struct page *page, unsigned long address, pgprot_t pgprot)
 271 {
 272         pgd_t *pgd;
 273         pud_t *pud;
 274         pmd_t *pmd;
 275         pte_t *pte;
 276
 277         if (!PageReserved(page))
 278                 printk(KERN_ERR "put_kernel_page: page at 0x%p not in reserved memory\n",
 279                        page_address(page));
 280
 281         pgd = pgd_offset_k(address);            /* note: this is NOT pgd_offset()! */
 282
 283         {
 284                 pud = pud_alloc(&init_mm, pgd, address);
 285                 if (!pud)
 286                         goto out;
 287                 pmd = pmd_alloc(&init_mm, pud, address);
 288                 if (!pmd)
 289                         goto out;
 290                 pte = pte_alloc_kernel(pmd, address);
 291                 if (!pte)
 292                         goto out;
 293                 if (!pte_none(*pte))
 294                         goto out;
 295                 set_pte(pte, mk_pte(page, pgprot));
 296         }
 297   out:
 298         /* no need for flush_tlb */
 299         return page;
 300 }
 301
 302 static void __init
 303 setup_gate (void)
 304 {
 305         struct page *page;
 306
 307         /*
 308          * Map the gate page twice: once read-only to export the ELF
 309          * headers etc. and once execute-only page to enable
 310          * privilege-promotion via "epc":
 311          */
 312         page = virt_to_page(ia64_imva(__start_gate_section));
 313         put_kernel_page(page, GATE_ADDR, PAGE_READONLY);
 314 #ifdef HAVE_BUGGY_SEGREL
 315         page = virt_to_page(ia64_imva(__start_gate_section + PAGE_SIZE));
 316         put_kernel_page(page, GATE_ADDR + PAGE_SIZE, PAGE_GATE);
 317 #else
 318         put_kernel_page(page, GATE_ADDR + PERCPU_PAGE_SIZE, PAGE_GATE);
 319         /* Fill in the holes (if any) with read-only zero pages: */
 320         {
 321                 unsigned long addr;
 322
 323                 for (addr = GATE_ADDR + PAGE_SIZE;
 324                      addr < GATE_ADDR + PERCPU_PAGE_SIZE;
 325                      addr += PAGE_SIZE)
 326                 {
 327                         put_kernel_page(ZERO_PAGE(0), addr,
 328                                         PAGE_READONLY);
 329                         put_kernel_page(ZERO_PAGE(0), addr + PERCPU_PAGE_SIZE,
 330                                         PAGE_READONLY);
 331                 }
 332         }
 333 #endif
 334         ia64_patch_gate();
 335 }
 336
 337 void __devinit
 338 ia64_mmu_init (void *my_cpu_data)
 339 {
 340         unsigned long psr, pta, impl_va_bits;
 341         extern void __devinit tlb_init (void);
 342
 343 #ifdef CONFIG_DISABLE_VHPT
 344 #       define VHPT_ENABLE_BIT  0
 345 #else
 346 #       define VHPT_ENABLE_BIT  1
 347 #endif
 348
 349         /* Pin mapping for percpu area into TLB */
 350         psr = ia64_clear_ic();
 351         ia64_itr(0x2, IA64_TR_PERCPU_DATA, PERCPU_ADDR,
 352                  pte_val(pfn_pte(__pa(my_cpu_data) >> PAGE_SHIFT, PAGE_KERNEL)),
 353                  PERCPU_PAGE_SHIFT);
 354
 355         ia64_set_psr(psr);
 356         ia64_srlz_i();
 357
 358         /*
 359          * Check if the virtually mapped linear page table (VMLPT) overlaps with a mapped
 360          * address space.  The IA-64 architecture guarantees that at least 50 bits of
 361          * virtual address space are implemented but if we pick a large enough page size
 362          * (e.g., 64KB), the mapped address space is big enough that it will overlap with
 363          * VMLPT.  I assume that once we run on machines big enough to warrant 64KB pages,
 364          * IMPL_VA_MSB will be significantly bigger, so this is unlikely to become a
 365          * problem in practice.  Alternatively, we could truncate the top of the mapped
 366          * address space to not permit mappings that would overlap with the VMLPT.
 367          * --davidm 00/12/06
 368          */
 369 #       define pte_bits                 3
 370 #       define mapped_space_bits        (3*(PAGE_SHIFT - pte_bits) + PAGE_SHIFT)
 371         /*
 372          * The virtual page table has to cover the entire implemented address space within
 373          * a region even though not all of this space may be mappable.  The reason for
 374          * this is that the Access bit and Dirty bit fault handlers perform
 375          * non-speculative accesses to the virtual page table, so the address range of the
 376          * virtual page table itself needs to be covered by virtual page table.
 377          */
 378 #       define vmlpt_bits               (impl_va_bits - PAGE_SHIFT + pte_bits)
 379 #       define POW2(n)                  (1ULL << (n))
 380
 381         impl_va_bits = ffz(~(local_cpu_data->unimpl_va_mask | (7UL << 61)));
 382
 383         if (impl_va_bits < 51 || impl_va_bits > 61)
 384                 panic("CPU has bogus IMPL_VA_MSB value of %lu!\n", impl_va_bits - 1);
 385         /*
 386          * mapped_space_bits - PAGE_SHIFT is the total number of ptes we need,
 387          * which must fit into "vmlpt_bits - pte_bits" slots. Second half of
 388          * the test makes sure that our mapped space doesn't overlap the
 389          * unimplemented hole in the middle of the region.
 390          */
 391         if ((mapped_space_bits - PAGE_SHIFT > vmlpt_bits - pte_bits) ||
 392             (mapped_space_bits > impl_va_bits - 1))
 393                 panic("Cannot build a big enough virtual-linear page table"
 394                       " to cover mapped address space.\n"
 395                       " Try using a smaller page size.\n");
 396
 397
 398         /* place the VMLPT at the end of each page-table mapped region: */
 399         pta = POW2(61) - POW2(vmlpt_bits);
 400
 401         /*
 402          * Set the (virtually mapped linear) page table address.  Bit
 403          * 8 selects between the short and long format, bits 2-7 the
 404          * size of the table, and bit 0 whether the VHPT walker is
 405          * enabled.
 406          */
 407         ia64_set_pta(pta | (0 << 8) | (vmlpt_bits << 2) | VHPT_ENABLE_BIT);
 408
 409         ia64_tlb_init();
 410
 411 #ifdef  CONFIG_HUGETLB_PAGE
 412         ia64_set_rr(HPAGE_REGION_BASE, HPAGE_SHIFT << 2);
 413         ia64_srlz_d();
 414 #endif
 415 }
 416
 417 #ifdef CONFIG_VIRTUAL_MEM_MAP
 418 int vmemmap_find_next_valid_pfn(int node, int i)
 419 {
 420         unsigned long end_address, hole_next_pfn;
 421         unsigned long stop_address;
 422         pg_data_t *pgdat = NODE_DATA(node);
 423
 424         end_address = (unsigned long) &vmem_map[pgdat->node_start_pfn + i];
 425         end_address = PAGE_ALIGN(end_address);
 426
 427         stop_address = (unsigned long) &vmem_map[
 428                 pgdat->node_start_pfn + pgdat->node_spanned_pages];
 429
 430         do {
 431                 pgd_t *pgd;
 432                 pud_t *pud;
 433                 pmd_t *pmd;
 434                 pte_t *pte;
 435
 436                 pgd = pgd_offset_k(end_address);
 437                 if (pgd_none(*pgd)) {
 438                         end_address += PGDIR_SIZE;
 439                         continue;
 440                 }
 441
 442                 pud = pud_offset(pgd, end_address);
 443                 if (pud_none(*pud)) {
 444                         end_address += PUD_SIZE;
 445                         continue;
 446                 }
 447
 448                 pmd = pmd_offset(pud, end_address);
 449                 if (pmd_none(*pmd)) {
 450                         end_address += PMD_SIZE;
 451                         continue;
 452                 }
 453
 454                 pte = pte_offset_kernel(pmd, end_address);
 455 retry_pte:
 456                 if (pte_none(*pte)) {
 457                         end_address += PAGE_SIZE;
 458                         pte++;
 459                         if ((end_address < stop_address) &&
 460                             (end_address != ALIGN(end_address, 1UL << PMD_SHIFT)))
 461                                 goto retry_pte;
 462                         continue;
 463                 }
 464                 /* Found next valid vmem_map page */
 465                 break;
 466         } while (end_address < stop_address);
 467
 468         end_address = min(end_address, stop_address);
 469         end_address = end_address - (unsigned long) vmem_map + sizeof(struct page) - 1;
 470         hole_next_pfn = end_address / sizeof(struct page);
 471         return hole_next_pfn - pgdat->node_start_pfn;
 472 }
 473
 474 int __init
 475 create_mem_map_page_table (u64 start, u64 end, void *arg)
 476 {
 477         unsigned long address, start_page, end_page;
 478         struct page *map_start, *map_end;
 479         int node;
 480         pgd_t *pgd;
 481         pud_t *pud;
 482         pmd_t *pmd;
 483         pte_t *pte;
 484
 485         map_start = vmem_map + (__pa(start) >> PAGE_SHIFT);
 486         map_end   = vmem_map + (__pa(end) >> PAGE_SHIFT);
 487
 488         start_page = (unsigned long) map_start & PAGE_MASK;
 489         end_page = PAGE_ALIGN((unsigned long) map_end);
 490         node = paddr_to_nid(__pa(start));
 491
 492         for (address = start_page; address < end_page; address += PAGE_SIZE) {
 493                 pgd = pgd_offset_k(address);
 494                 if (pgd_none(*pgd))
 495                         pgd_populate(&init_mm, pgd, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
 496                 pud = pud_offset(pgd, address);
 497
 498                 if (pud_none(*pud))
 499                         pud_populate(&init_mm, pud, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
 500                 pmd = pmd_offset(pud, address);
 501
 502                 if (pmd_none(*pmd))
 503                         pmd_populate_kernel(&init_mm, pmd, alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE));
 504                 pte = pte_offset_kernel(pmd, address);
 505
 506                 if (pte_none(*pte))
 507                         set_pte(pte, pfn_pte(__pa(alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE)) >> PAGE_SHIFT,
 508                                              PAGE_KERNEL));
 509         }
 510         return 0;
 511 }
 512
 513 struct memmap_init_callback_data {
 514         struct page *start;
 515         struct page *end;
 516         int nid;
 517         unsigned long zone;
 518 };
 519
 520 static int
 521 virtual_memmap_init (u64 start, u64 end, void *arg)
 522 {
 523         struct memmap_init_callback_data *args;
 524         struct page *map_start, *map_end;
 525
 526         args = (struct memmap_init_callback_data *) arg;
 527         map_start = vmem_map + (__pa(start) >> PAGE_SHIFT);
 528         map_end   = vmem_map + (__pa(end) >> PAGE_SHIFT);
 529
 530         if (map_start < args->start)
 531                 map_start = args->start;
 532         if (map_end > args->end)
 533                 map_end = args->end;
 534
 535         /*
 536          * We have to initialize "out of bounds" struct page elements that fit completely
 537          * on the same pages that were allocated for the "in bounds" elements because they
 538          * may be referenced later (and found to be "reserved").
 539          */
 540         map_start -= ((unsigned long) map_start & (PAGE_SIZE - 1)) / sizeof(struct page);
 541         map_end += ((PAGE_ALIGN((unsigned long) map_end) - (unsigned long) map_end)
 542                     / sizeof(struct page));
 543
 544         if (map_start < map_end)
 545                 memmap_init_zone((unsigned long)(map_end - map_start),
 546                                  args->nid, args->zone, page_to_pfn(map_start));
 547         return 0;
 548 }
 549
 550 void
 551 memmap_init (unsigned long size, int nid, unsigned long zone,
 552              unsigned long start_pfn)
 553 {
 554         if (!vmem_map)
 555                 memmap_init_zone(size, nid, zone, start_pfn);
 556         else {
 557                 struct page *start;
 558                 struct memmap_init_callback_data args;
 559
 560                 start = pfn_to_page(start_pfn);
 561                 args.start = start;
 562                 args.end = start + size;
 563                 args.nid = nid;
 564                 args.zone = zone;
 565
 566                 efi_memmap_walk(virtual_memmap_init, &args);
 567         }
 568 }
 569
 570 int
 571 ia64_pfn_valid (unsigned long pfn)
 572 {
 573         char byte;
 574         struct page *pg = pfn_to_page(pfn);
 575
 576         return     (__get_user(byte, (char __user *) pg) == 0)
 577                 && ((((u64)pg & PAGE_MASK) == (((u64)(pg + 1) - 1) & PAGE_MASK))
 578                         || (__get_user(byte, (char __user *) (pg + 1) - 1) == 0));
 579 }
 580 EXPORT_SYMBOL(ia64_pfn_valid);
 581
 582 int __init
 583 find_largest_hole (u64 start, u64 end, void *arg)
 584 {
 585         u64 *max_gap = arg;
 586
 587         static u64 last_end = PAGE_OFFSET;
 588
 589         /* NOTE: this algorithm assumes efi memmap table is ordered */
 590
 591         if (*max_gap < (start - last_end))
 592                 *max_gap = start - last_end;
 593         last_end = end;
 594         return 0;
 595 }
 596
 597 int __init
 598 register_active_ranges(u64 start, u64 end, void *arg)
 599 {
 600         add_active_range(0, __pa(start) >> PAGE_SHIFT, __pa(end) >> PAGE_SHIFT);
 601         return 0;
 602 }
 603 #endif /* CONFIG_VIRTUAL_MEM_MAP */
 604
 605 static int __init
 606 count_reserved_pages (u64 start, u64 end, void *arg)
 607 {
 608         unsigned long num_reserved = 0;
 609         unsigned long *count = arg;
 610
 611         for (; start < end; start += PAGE_SIZE)
 612                 if (PageReserved(virt_to_page(start)))
 613                         ++num_reserved;
 614         *count += num_reserved;
 615         return 0;
 616 }
 617
 618 /*
 619  * Boot command-line option "nolwsys" can be used to disable the use of any light-weight
 620  * system call handler.  When this option is in effect, all fsyscalls will end up bubbling
 621  * down into the kernel and calling the normal (heavy-weight) syscall handler.  This is
 622  * useful for performance testing, but conceivably could also come in handy for debugging
 623  * purposes.
 624  */
 625
 626 static int nolwsys __initdata;
 627
 628 static int __init
 629 nolwsys_setup (char *s)
 630 {
 631         nolwsys = 1;
 632         return 1;
 633 }
 634
 635 __setup("nolwsys", nolwsys_setup);
 636
 637 void __init
 638 mem_init (void)
 639 {
 640         long reserved_pages, codesize, datasize, initsize;
 641         pg_data_t *pgdat;
 642         int i;
 643         static struct kcore_list kcore_mem, kcore_vmem, kcore_kernel;
 644
 645         BUG_ON(PTRS_PER_PGD * sizeof(pgd_t) != PAGE_SIZE);
 646         BUG_ON(PTRS_PER_PMD * sizeof(pmd_t) != PAGE_SIZE);
 647         BUG_ON(PTRS_PER_PTE * sizeof(pte_t) != PAGE_SIZE);
 648
 649 #ifdef CONFIG_PCI
 650         /*
 651          * This needs to be called _after_ the command line has been parsed but _before_
 652          * any drivers that may need the PCI DMA interface are initialized or bootmem has
 653          * been freed.
 654          */
 655         platform_dma_init();
 656 #endif
 657
 658 #ifdef CONFIG_FLATMEM
 659         if (!mem_map)
 660                 BUG();
 661         max_mapnr = max_low_pfn;
 662 #endif
 663
 664         high_memory = __va(max_low_pfn * PAGE_SIZE);
 665
 666         kclist_add(&kcore_mem, __va(0), max_low_pfn * PAGE_SIZE);
 667         kclist_add(&kcore_vmem, (void *)VMALLOC_START, VMALLOC_END-VMALLOC_START);
 668         kclist_add(&kcore_kernel, _stext, _end - _stext);
 669
 670         for_each_online_pgdat(pgdat)
 671                 if (pgdat->bdata->node_bootmem_map)
 672                         totalram_pages += free_all_bootmem_node(pgdat);
 673
 674         reserved_pages = 0;
 675         efi_memmap_walk(count_reserved_pages, &reserved_pages);
 676
 677         codesize =  (unsigned long) _etext - (unsigned long) _stext;
 678         datasize =  (unsigned long) _edata - (unsigned long) _etext;
 679         initsize =  (unsigned long) __init_end - (unsigned long) __init_begin;
 680
 681         printk(KERN_INFO "Memory: %luk/%luk available (%luk code, %luk reserved, "
 682                "%luk data, %luk init)\n", (unsigned long) nr_free_pages() << (PAGE_SHIFT - 10),
 683                num_physpages << (PAGE_SHIFT - 10), codesize >> 10,
 684                reserved_pages << (PAGE_SHIFT - 10), datasize >> 10, initsize >> 10);
 685
 686
 687         /*
 688          * For fsyscall entrpoints with no light-weight handler, use the ordinary
 689          * (heavy-weight) handler, but mark it by setting bit 0, so the fsyscall entry
 690          * code can tell them apart.
 691          */
 692         for (i = 0; i < NR_syscalls; ++i) {
 693                 extern unsigned long fsyscall_table[NR_syscalls];
 694                 extern unsigned long sys_call_table[NR_syscalls];
 695
 696                 if (!fsyscall_table[i] || nolwsys)
 697                         fsyscall_table[i] = sys_call_table[i] | 1;
 698         }
 699         setup_gate();
 700
 701 #ifdef CONFIG_IA32_SUPPORT
 702         ia32_mem_init();
 703 #endif
 704 }
 705
 706 #ifdef CONFIG_MEMORY_HOTPLUG
 707 void online_page(struct page *page)
 708 {
 709         ClearPageReserved(page);
 710         init_page_count(page);
 711         __free_page(page);
 712         totalram_pages++;
 713         num_physpages++;
 714 }
 715
 716 int arch_add_memory(int nid, u64 start, u64 size)
 717 {
 718         pg_data_t *pgdat;
 719         struct zone *zone;
 720         unsigned long start_pfn = start >> PAGE_SHIFT;
 721         unsigned long nr_pages = size >> PAGE_SHIFT;
 722         int ret;
 723
 724         pgdat = NODE_DATA(nid);
 725
 726         zone = pgdat->node_zones + ZONE_NORMAL;
 727         ret = __add_pages(zone, start_pfn, nr_pages);
 728
 729         if (ret)
 730                 printk("%s: Problem encountered in __add_pages() as ret=%d\n",
 731                        __FUNCTION__,  ret);
 732
 733         return ret;
 734 }
 735
 736 int remove_memory(u64 start, u64 size)
 737 {
 738         return -EINVAL;
 739 }
 740 EXPORT_SYMBOL_GPL(remove_memory);
 741 #endif