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