arch/i386/mm/init.c

   1 /*
   2  *  linux/arch/i386/mm/init.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  *
   6  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
   7  */
   8
   9 #include <linux/config.h>
  10 #include <linux/module.h>
  11 #include <linux/signal.h>
  12 #include <linux/sched.h>
  13 #include <linux/kernel.h>
  14 #include <linux/errno.h>
  15 #include <linux/string.h>
  16 #include <linux/types.h>
  17 #include <linux/ptrace.h>
  18 #include <linux/mman.h>
  19 #include <linux/mm.h>
  20 #include <linux/hugetlb.h>
  21 #include <linux/swap.h>
  22 #include <linux/smp.h>
  23 #include <linux/init.h>
  24 #include <linux/highmem.h>
  25 #include <linux/pagemap.h>
  26 #include <linux/bootmem.h>
  27 #include <linux/slab.h>
  28 #include <linux/proc_fs.h>
  29 #include <linux/efi.h>
  30
  31 #include <asm/processor.h>
  32 #include <asm/system.h>
  33 #include <asm/uaccess.h>
  34 #include <asm/pgtable.h>
  35 #include <asm/dma.h>
  36 #include <asm/fixmap.h>
  37 #include <asm/e820.h>
  38 #include <asm/apic.h>
  39 #include <asm/tlb.h>
  40 #include <asm/tlbflush.h>
  41 #include <asm/sections.h>
  42 #include <asm/desc.h>
  43
  44 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  45 unsigned long highstart_pfn, highend_pfn;
  46
  47 static int do_test_wp_bit(void);
  48
  49 static inline int page_kills_ppro(unsigned long pagenr)
  50 {
  51         if (pagenr >= 0x70000 && pagenr <= 0x7003F)
  52                 return 1;
  53         return 0;
  54 }
  55
  56 extern int is_available_memory(efi_memory_desc_t *);
  57
  58 int page_is_ram(unsigned long pagenr)
  59 {
  60         int i;
  61         unsigned long addr, end;
  62
  63         if (efi_enabled) {
  64                 efi_memory_desc_t *md;
  65
  66                 for (i = 0; i < memmap.nr_map; i++) {
  67                         md = &memmap.map[i];
  68                         if (!is_available_memory(md))
  69                                 continue;
  70                         addr = (md->phys_addr+PAGE_SIZE-1) >> PAGE_SHIFT;
  71                         end = (md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT)) >> PAGE_SHIFT;
  72
  73                         if ((pagenr >= addr) && (pagenr < end))
  74                                 return 1;
  75                 }
  76                 return 0;
  77         }
  78
  79         for (i = 0; i < e820.nr_map; i++) {
  80
  81                 if (e820.map[i].type != E820_RAM)       /* not usable memory */
  82                         continue;
  83                 /*
  84                  *      !!!FIXME!!! Some BIOSen report areas as RAM that
  85                  *      are not. Notably the 640->1Mb area. We need a sanity
  86                  *      check here.
  87                  */
  88                 addr = (e820.map[i].addr+PAGE_SIZE-1) >> PAGE_SHIFT;
  89                 end = (e820.map[i].addr+e820.map[i].size) >> PAGE_SHIFT;
  90                 if  ((pagenr >= addr) && (pagenr < end))
  91                         return 1;
  92         }
  93         return 0;
  94 }
  95
  96 /* To enable modules to check if a page is in RAM */
  97 int pfn_is_ram(unsigned long pfn)
  98 {
  99         return (page_is_ram(pfn));
 100 }
 101
 102
 103 pte_t *kmap_pte;
 104
 105 EXPORT_SYMBOL(kmap_pte);
 106
 107 #define kmap_get_fixmap_pte(vaddr)                                      \
 108         pte_offset_kernel(pmd_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr))
 109
 110 void __init kmap_init(void)
 111 {
 112         kmap_pte = kmap_get_fixmap_pte(__fix_to_virt(FIX_KMAP_BEGIN));
 113 }
 114
 115 void __init one_highpage_init(struct page *page, int pfn, int bad_ppro)
 116 {
 117         if (page_is_ram(pfn) && !(bad_ppro && page_kills_ppro(pfn))) {
 118                 ClearPageReserved(page);
 119                 set_bit(PG_highmem, &page->flags);
 120                 set_page_count(page, 1);
 121                 __free_page(page);
 122                 totalhigh_pages++;
 123         } else
 124                 SetPageReserved(page);
 125 }
 126
 127 EXPORT_SYMBOL_GPL(page_is_ram);
 128
 129 #ifdef CONFIG_HIGHMEM
 130
 131 #ifndef CONFIG_DISCONTIGMEM
 132 void __init set_highmem_pages_init(int bad_ppro)
 133 {
 134         int pfn;
 135         for (pfn = highstart_pfn; pfn < highend_pfn; pfn++)
 136                 one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro);
 137         totalram_pages += totalhigh_pages;
 138 }
 139 #else
 140 extern void set_highmem_pages_init(int);
 141 #endif /* !CONFIG_DISCONTIGMEM */
 142 #else
 143 # define set_highmem_pages_init(bad_ppro) do { } while (0)
 144 #endif
 145
 146 unsigned long long __PAGE_KERNEL = _PAGE_KERNEL;
 147 unsigned long long __PAGE_KERNEL_EXEC = _PAGE_KERNEL_EXEC;
 148
 149 #ifndef CONFIG_DISCONTIGMEM
 150 #define remap_numa_kva() do {} while (0)
 151 #else
 152 extern void __init remap_numa_kva(void);
 153 #endif
 154
 155 static __init void prepare_pagetables(pgd_t *pgd_base, unsigned long address)
 156 {
 157         pgd_t *pgd;
 158         pmd_t *pmd;
 159         pte_t *pte;
 160
 161         pgd = pgd_base + pgd_index(address);
 162         pmd = pmd_offset(pgd, address);
 163         if (!pmd_present(*pmd)) {
 164                 pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
 165                 set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte)));
 166         }
 167 }
 168
 169 static void __init fixrange_init (unsigned long start, unsigned long end, pgd_t *pgd_base)
 170 {
 171         unsigned long vaddr;
 172
 173         for (vaddr = start; vaddr != end; vaddr += PAGE_SIZE)
 174                 prepare_pagetables(pgd_base, vaddr);
 175 }
 176
 177 void setup_identity_mappings(pgd_t *pgd_base, unsigned long start, unsigned long end)
 178 {
 179         unsigned long vaddr;
 180         pgd_t *pgd;
 181         int i, j, k;
 182         pmd_t *pmd;
 183         pte_t *pte, *pte_base;
 184
 185         pgd = pgd_base;
 186
 187         for (i = 0; i < PTRS_PER_PGD; pgd++, i++) {
 188                 vaddr = i*PGDIR_SIZE;
 189                 if (end && (vaddr >= end))
 190                         break;
 191                 pmd = pmd_offset(pgd, 0);
 192                 for (j = 0; j < PTRS_PER_PMD; pmd++, j++) {
 193                         vaddr = i*PGDIR_SIZE + j*PMD_SIZE;
 194                         if (end && (vaddr >= end))
 195                                 break;
 196                         if (vaddr < start)
 197                                 continue;
 198                         if (cpu_has_pse) {
 199                                 unsigned long __pe;
 200
 201                                 set_in_cr4(X86_CR4_PSE);
 202                                 boot_cpu_data.wp_works_ok = 1;
 203                                 __pe = _KERNPG_TABLE + _PAGE_PSE + vaddr - start;
 204                                 /* Make it "global" too if supported */
 205                                 if (cpu_has_pge) {
 206                                         set_in_cr4(X86_CR4_PGE);
 207 #if !defined(CONFIG_X86_SWITCH_PAGETABLES)
 208                                         __pe += _PAGE_GLOBAL;
 209                                         __PAGE_KERNEL |= _PAGE_GLOBAL;
 210 #endif
 211                                 }
 212                                 set_pmd(pmd, __pmd(__pe));
 213                                 continue;
 214                         }
 215                         if (!pmd_present(*pmd))
 216                                 pte_base = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
 217                         else
 218                                 pte_base = pte_offset_kernel(pmd, 0);
 219                         pte = pte_base;
 220                         for (k = 0; k < PTRS_PER_PTE; pte++, k++) {
 221                                 vaddr = i*PGDIR_SIZE + j*PMD_SIZE + k*PAGE_SIZE;
 222                                 if (end && (vaddr >= end))
 223                                         break;
 224                                 if (vaddr < start)
 225                                         continue;
 226                                 *pte = mk_pte_phys(vaddr-start, PAGE_KERNEL);
 227                         }
 228                         set_pmd(pmd, __pmd(_KERNPG_TABLE + __pa(pte_base)));
 229                 }
 230         }
 231 }
 232
 233 static void __init pagetable_init (void)
 234 {
 235         unsigned long vaddr, end;
 236         pgd_t *pgd_base;
 237 #ifdef CONFIG_X86_PAE
 238         int i;
 239 #endif
 240
 241         /*
 242          * This can be zero as well - no problem, in that case we exit
 243          * the loops anyway due to the PTRS_PER_* conditions.
 244          */
 245         end = (unsigned long)__va(max_low_pfn*PAGE_SIZE);
 246
 247         pgd_base = swapper_pg_dir;
 248 #ifdef CONFIG_X86_PAE
 249         /*
 250          * It causes too many problems if there's no proper pmd set up
 251          * for all 4 entries of the PGD - so we allocate all of them.
 252          * PAE systems will not miss this extra 4-8K anyway ...
 253          */
 254         for (i = 0; i < PTRS_PER_PGD; i++) {
 255                 pmd_t *pmd = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
 256                 set_pgd(pgd_base + i, __pgd(__pa(pmd) + 0x1));
 257         }
 258 #endif
 259         /*
 260          * Set up lowmem-sized identity mappings at PAGE_OFFSET:
 261          */
 262         setup_identity_mappings(pgd_base, PAGE_OFFSET, end);
 263
 264         /*
 265          * Add flat-mode identity-mappings - SMP needs it when
 266          * starting up on an AP from real-mode. (In the non-PAE
 267          * case we already have these mappings through head.S.)
 268          * All user-space mappings are explicitly cleared after
 269          * SMP startup.
 270          */
 271 #if defined(CONFIG_SMP) && defined(CONFIG_X86_PAE)
 272         setup_identity_mappings(pgd_base, 0, 16*1024*1024);
 273 #endif
 274         remap_numa_kva();
 275
 276         /*
 277          * Fixed mappings, only the page table structure has to be
 278          * created - mappings will be set by set_fixmap():
 279          */
 280         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 281         fixrange_init(vaddr, 0, pgd_base);
 282
 283 #ifdef CONFIG_HIGHMEM
 284         {
 285                 pgd_t *pgd;
 286                 pmd_t *pmd;
 287                 pte_t *pte;
 288
 289                 /*
 290                  * Permanent kmaps:
 291                  */
 292                 vaddr = PKMAP_BASE;
 293                 fixrange_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
 294
 295                 pgd = swapper_pg_dir + pgd_index(vaddr);
 296                 pmd = pmd_offset(pgd, vaddr);
 297                 pte = pte_offset_kernel(pmd, vaddr);
 298                 pkmap_page_table = pte;
 299         }
 300 #endif
 301 }
 302
 303 /*
 304  * Clear kernel pagetables in a PMD_SIZE-aligned range.
 305  */
 306 static void clear_mappings(pgd_t *pgd_base, unsigned long start, unsigned long end)
 307 {
 308         unsigned long vaddr;
 309         pgd_t *pgd;
 310         pmd_t *pmd;
 311         int i, j;
 312
 313         pgd = pgd_base;
 314
 315         for (i = 0; i < PTRS_PER_PGD; pgd++, i++) {
 316                 vaddr = i*PGDIR_SIZE;
 317                 if (end && (vaddr >= end))
 318                         break;
 319                 pmd = pmd_offset(pgd, 0);
 320                 for (j = 0; j < PTRS_PER_PMD; pmd++, j++) {
 321                         vaddr = i*PGDIR_SIZE + j*PMD_SIZE;
 322                         if (end && (vaddr >= end))
 323                                 break;
 324                         if (vaddr < start)
 325                                 continue;
 326                         pmd_clear(pmd);
 327                 }
 328         }
 329         flush_tlb_all();
 330 }
 331
 332 void zap_low_mappings(void)
 333 {
 334         printk("zapping low mappings.\n");
 335         /*
 336          * Zap initial low-memory mappings.
 337          */
 338         clear_mappings(swapper_pg_dir, 0, 16*1024*1024);
 339 }
 340
 341 #ifndef CONFIG_DISCONTIGMEM
 342 void __init zone_sizes_init(void)
 343 {
 344         unsigned long zones_size[MAX_NR_ZONES] = {0, 0, 0};
 345         unsigned int max_dma, high, low;
 346
 347         max_dma = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
 348         low = max_low_pfn;
 349         high = highend_pfn;
 350
 351         if (low < max_dma)
 352                 zones_size[ZONE_DMA] = low;
 353         else {
 354                 zones_size[ZONE_DMA] = max_dma;
 355                 zones_size[ZONE_NORMAL] = low - max_dma;
 356 #ifdef CONFIG_HIGHMEM
 357                 zones_size[ZONE_HIGHMEM] = high - low;
 358 #endif
 359         }
 360         free_area_init(zones_size);
 361 }
 362 #else
 363 extern void zone_sizes_init(void);
 364 #endif /* !CONFIG_DISCONTIGMEM */
 365
 366 static int disable_nx __initdata = 0;
 367 u64 __supported_pte_mask = ~_PAGE_NX;
 368
 369 /*
 370  * noexec = on|off
 371  *
 372  * Control non executable mappings.
 373  *
 374  * on      Enable
 375  * off     Disable (disables exec-shield too)
 376  */
 377 static int __init noexec_setup(char *str)
 378 {
 379         if (!strncmp(str, "on",2) && cpu_has_nx) {
 380                 __supported_pte_mask |= _PAGE_NX;
 381                 disable_nx = 0;
 382         } else if (!strncmp(str,"off",3)) {
 383                 disable_nx = 1;
 384                 __supported_pte_mask &= ~_PAGE_NX;
 385                 exec_shield = 0;
 386         }
 387         return 1;
 388 }
 389
 390 __setup("noexec=", noexec_setup);
 391
 392 #ifdef CONFIG_X86_PAE
 393 int nx_enabled = 0;
 394
 395 static void __init set_nx(void)
 396 {
 397         unsigned int v[4], l, h;
 398
 399         if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {
 400                 cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);
 401                 if ((v[3] & (1 << 20)) && !disable_nx) {
 402                         rdmsr(MSR_EFER, l, h);
 403                         l |= EFER_NX;
 404                         wrmsr(MSR_EFER, l, h);
 405                         nx_enabled = 1;
 406                         __supported_pte_mask |= _PAGE_NX;
 407                 }
 408         }
 409 }
 410 /*
 411  * Enables/disables executability of a given kernel page and
 412  * returns the previous setting.
 413  */
 414 int __init set_kernel_exec(unsigned long vaddr, int enable)
 415 {
 416         pte_t *pte;
 417         int ret = 1;
 418
 419         if (!nx_enabled)
 420                 goto out;
 421
 422         pte = lookup_address(vaddr);
 423         BUG_ON(!pte);
 424
 425         if (!pte_exec_kernel(*pte))
 426                 ret = 0;
 427
 428         if (enable)
 429                 pte->pte_high &= ~(1 << (_PAGE_BIT_NX - 32));
 430         else
 431                 pte->pte_high |= 1 << (_PAGE_BIT_NX - 32);
 432         __flush_tlb_all();
 433 out:
 434         return ret;
 435 }
 436
 437 #endif
 438
 439 /*
 440  * paging_init() sets up the page tables - note that the first 8MB are
 441  * already mapped by head.S.
 442  *
 443  * This routines also unmaps the page at virtual kernel address 0, so
 444  * that we can trap those pesky NULL-reference errors in the kernel.
 445  */
 446 void __init paging_init(void)
 447 {
 448 #ifdef CONFIG_X86_PAE
 449         set_nx();
 450         if (nx_enabled)
 451                 printk("NX (Execute Disable) protection: active\n");
 452 #endif
 453
 454         pagetable_init();
 455
 456         load_cr3(swapper_pg_dir);
 457
 458 #ifdef CONFIG_X86_PAE
 459         /*
 460          * We will bail out later - printk doesn't work right now so
 461          * the user would just see a hanging kernel.
 462          */
 463         if (cpu_has_pae)
 464                 set_in_cr4(X86_CR4_PAE);
 465 #endif
 466         __flush_tlb_all();
 467         /*
 468          * Subtle. SMP is doing it's boot stuff late (because it has to
 469          * fork idle threads) - but it also needs low mappings for the
 470          * protected-mode entry to work. We zap these entries only after
 471          * the WP-bit has been tested.
 472          */
 473 #ifndef CONFIG_SMP
 474         zap_low_mappings();
 475 #endif
 476         kmap_init();
 477         zone_sizes_init();
 478 }
 479
 480 /*
 481  * Test if the WP bit works in supervisor mode. It isn't supported on 386's
 482  * and also on some strange 486's (NexGen etc.). All 586+'s are OK. This
 483  * used to involve black magic jumps to work around some nasty CPU bugs,
 484  * but fortunately the switch to using exceptions got rid of all that.
 485  */
 486
 487 void __init test_wp_bit(void)
 488 {
 489         printk("Checking if this processor honours the WP bit even in supervisor mode... ");
 490
 491         /* Any page-aligned address will do, the test is non-destructive */
 492         __set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_READONLY);
 493         boot_cpu_data.wp_works_ok = do_test_wp_bit();
 494         clear_fixmap(FIX_WP_TEST);
 495
 496         if (!boot_cpu_data.wp_works_ok) {
 497                 printk("No.\n");
 498 #ifdef CONFIG_X86_WP_WORKS_OK
 499                 panic("This kernel doesn't support CPU's with broken WP. Recompile it for a 386!");
 500 #endif
 501         } else {
 502                 printk("Ok.\n");
 503         }
 504 }
 505
 506 #ifndef CONFIG_DISCONTIGMEM
 507 static void __init set_max_mapnr_init(void)
 508 {
 509 #ifdef CONFIG_HIGHMEM
 510         highmem_start_page = pfn_to_page(highstart_pfn);
 511         max_mapnr = num_physpages = highend_pfn;
 512 #else
 513         max_mapnr = num_physpages = max_low_pfn;
 514 #endif
 515 }
 516 #define __free_all_bootmem() free_all_bootmem()
 517 #else
 518 #define __free_all_bootmem() free_all_bootmem_node(NODE_DATA(0))
 519 extern void set_max_mapnr_init(void);
 520 #endif /* !CONFIG_DISCONTIGMEM */
 521
 522 static struct kcore_list kcore_mem, kcore_vmalloc;
 523
 524 void __init mem_init(void)
 525 {
 526         extern int ppro_with_ram_bug(void);
 527         int codesize, reservedpages, datasize, initsize;
 528         int tmp;
 529         int bad_ppro;
 530
 531 #ifndef CONFIG_DISCONTIGMEM
 532         if (!mem_map)
 533                 BUG();
 534 #endif
 535
 536         bad_ppro = ppro_with_ram_bug();
 537
 538 #ifdef CONFIG_HIGHMEM
 539         /* check that fixmap and pkmap do not overlap */
 540         if (PKMAP_BASE+LAST_PKMAP*PAGE_SIZE >= FIXADDR_START) {
 541                 printk(KERN_ERR "fixmap and kmap areas overlap - this will crash\n");
 542                 printk(KERN_ERR "pkstart: %lxh pkend: %lxh fixstart %lxh\n",
 543                                 PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE, FIXADDR_START);
 544                 BUG();
 545         }
 546 #endif
 547
 548         set_max_mapnr_init();
 549
 550 #ifdef CONFIG_HIGHMEM
 551         high_memory = (void *) __va(highstart_pfn * PAGE_SIZE);
 552 #else
 553         high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
 554 #endif
 555
 556         /* this will put all low memory onto the freelists */
 557         totalram_pages += __free_all_bootmem();
 558
 559         reservedpages = 0;
 560         for (tmp = 0; tmp < max_low_pfn; tmp++)
 561                 /*
 562                  * Only count reserved RAM pages
 563                  */
 564                 if (page_is_ram(tmp) && PageReserved(pfn_to_page(tmp)))
 565                         reservedpages++;
 566
 567         set_highmem_pages_init(bad_ppro);
 568
 569         codesize =  (unsigned long) &_etext - (unsigned long) &_text;
 570         datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
 571         initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
 572
 573         kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT);
 574         kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 575                    VMALLOC_END-VMALLOC_START);
 576
 577         printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem)\n",
 578                 (unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
 579                 num_physpages << (PAGE_SHIFT-10),
 580                 codesize >> 10,
 581                 reservedpages << (PAGE_SHIFT-10),
 582                 datasize >> 10,
 583                 initsize >> 10,
 584                 (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10))
 585                );
 586
 587 #ifdef CONFIG_X86_PAE
 588         if (!cpu_has_pae)
 589                 panic("cannot execute a PAE-enabled kernel on a PAE-less CPU!");
 590 #endif
 591         if (boot_cpu_data.wp_works_ok < 0)
 592                 test_wp_bit();
 593
 594         entry_trampoline_setup();
 595         default_ldt_page = virt_to_page(default_ldt);
 596         load_LDT(&init_mm.context);
 597 }
 598
 599 kmem_cache_t *pgd_cache, *pmd_cache, *kpmd_cache;
 600
 601 void __init pgtable_cache_init(void)
 602 {
 603         void (*ctor)(void *, kmem_cache_t *, unsigned long);
 604         void (*dtor)(void *, kmem_cache_t *, unsigned long);
 605
 606         if (PTRS_PER_PMD > 1) {
 607                 pmd_cache = kmem_cache_create("pmd",
 608                                         PTRS_PER_PMD*sizeof(pmd_t),
 609                                         PTRS_PER_PMD*sizeof(pmd_t),
 610                                         0,
 611                                         pmd_ctor,
 612                                         NULL);
 613                 if (!pmd_cache)
 614                         panic("pgtable_cache_init(): cannot create pmd cache");
 615
 616                 if (TASK_SIZE > PAGE_OFFSET) {
 617                         kpmd_cache = kmem_cache_create("kpmd",
 618                                         PTRS_PER_PMD*sizeof(pmd_t),
 619                                         PTRS_PER_PMD*sizeof(pmd_t),
 620                                         0,
 621                                         kpmd_ctor,
 622                                         NULL);
 623                         if (!kpmd_cache)
 624                                 panic("pgtable_cache_init(): "
 625                                                 "cannot create kpmd cache");
 626                 }
 627         }
 628
 629         if (PTRS_PER_PMD == 1 || TASK_SIZE <= PAGE_OFFSET)
 630                 ctor = pgd_ctor;
 631         else
 632                 ctor = NULL;
 633
 634         if (PTRS_PER_PMD == 1 && TASK_SIZE <= PAGE_OFFSET)
 635                 dtor = pgd_dtor;
 636         else
 637                 dtor = NULL;
 638
 639         pgd_cache = kmem_cache_create("pgd",
 640                                 PTRS_PER_PGD*sizeof(pgd_t),
 641                                 PTRS_PER_PGD*sizeof(pgd_t),
 642                                 0,
 643                                 ctor,
 644                                 dtor);
 645         if (!pgd_cache)
 646                 panic("pgtable_cache_init(): Cannot create pgd cache");
 647 }
 648
 649 /*
 650  * This function cannot be __init, since exceptions don't work in that
 651  * section.  Put this after the callers, so that it cannot be inlined.
 652  */
 653 static int noinline do_test_wp_bit(void)
 654 {
 655         char tmp_reg;
 656         int flag;
 657
 658         __asm__ __volatile__(
 659                 "       movb %0,%1      \n"
 660                 "1:     movb %1,%0      \n"
 661                 "       xorl %2,%2      \n"
 662                 "2:                     \n"
 663                 ".section __ex_table,\"a\"\n"
 664                 "       .align 4        \n"
 665                 "       .long 1b,2b     \n"
 666                 ".previous              \n"
 667                 :"=m" (*(char *)fix_to_virt(FIX_WP_TEST)),
 668                  "=q" (tmp_reg),
 669                  "=r" (flag)
 670                 :"2" (1)
 671                 :"memory");
 672
 673         return flag;
 674 }
 675
 676 void free_initmem(void)
 677 {
 678         unsigned long addr;
 679
 680         addr = (unsigned long)(&__init_begin);
 681         for (; addr < (unsigned long)(&__init_end); addr += PAGE_SIZE) {
 682                 ClearPageReserved(virt_to_page(addr));
 683                 set_page_count(virt_to_page(addr), 1);
 684                 free_page(addr);
 685                 totalram_pages++;
 686         }
 687         printk (KERN_INFO "Freeing unused kernel memory: %dk freed\n", (__init_end - __init_begin) >> 10);
 688 }
 689
 690 #ifdef CONFIG_BLK_DEV_INITRD
 691 void free_initrd_mem(unsigned long start, unsigned long end)
 692 {
 693         if (start < end)
 694                 printk (KERN_INFO "Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
 695         for (; start < end; start += PAGE_SIZE) {
 696                 ClearPageReserved(virt_to_page(start));
 697                 set_page_count(virt_to_page(start), 1);
 698                 free_page(start);
 699                 totalram_pages++;
 700         }
 701 }
 702 #endif