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/poison.h>
  27 #include <linux/bootmem.h>
  28 #include <linux/slab.h>
  29 #include <linux/proc_fs.h>
  30 #include <linux/efi.h>
  31 #include <linux/memory_hotplug.h>
  32 #include <linux/initrd.h>
  33 #include <linux/cpumask.h>
  34
  35 #include <asm/processor.h>
  36 #include <asm/system.h>
  37 #include <asm/uaccess.h>
  38 #include <asm/pgtable.h>
  39 #include <asm/dma.h>
  40 #include <asm/fixmap.h>
  41 #include <asm/e820.h>
  42 #include <asm/apic.h>
  43 #include <asm/tlb.h>
  44 #include <asm/tlbflush.h>
  45 #include <asm/sections.h>
  46
  47 unsigned int __VMALLOC_RESERVE = 128 << 20;
  48
  49 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  50 unsigned long highstart_pfn, highend_pfn;
  51
  52 static int noinline do_test_wp_bit(void);
  53
  54 /*
  55  * Creates a middle page table and puts a pointer to it in the
  56  * given global directory entry. This only returns the gd entry
  57  * in non-PAE compilation mode, since the middle layer is folded.
  58  */
  59 static pmd_t * __init one_md_table_init(pgd_t *pgd)
  60 {
  61         pud_t *pud;
  62         pmd_t *pmd_table;
  63
  64 #ifdef CONFIG_X86_PAE
  65         pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
  66         set_pgd(pgd, __pgd(__pa(pmd_table) | _PAGE_PRESENT));
  67         pud = pud_offset(pgd, 0);
  68         if (pmd_table != pmd_offset(pud, 0))
  69                 BUG();
  70 #else
  71         pud = pud_offset(pgd, 0);
  72         pmd_table = pmd_offset(pud, 0);
  73 #endif
  74
  75         return pmd_table;
  76 }
  77
  78 /*
  79  * Create a page table and place a pointer to it in a middle page
  80  * directory entry.
  81  */
  82 static pte_t * __init one_page_table_init(pmd_t *pmd)
  83 {
  84         if (pmd_none(*pmd)) {
  85                 pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
  86                 set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
  87                 if (page_table != pte_offset_kernel(pmd, 0))
  88                         BUG();
  89
  90                 return page_table;
  91         }
  92
  93         return pte_offset_kernel(pmd, 0);
  94 }
  95
  96 /*
  97  * This function initializes a certain range of kernel virtual memory
  98  * with new bootmem page tables, everywhere page tables are missing in
  99  * the given range.
 100  */
 101
 102 /*
 103  * NOTE: The pagetables are allocated contiguous on the physical space
 104  * so we can cache the place of the first one and move around without
 105  * checking the pgd every time.
 106  */
 107 static void __init page_table_range_init (unsigned long start, unsigned long end, pgd_t *pgd_base)
 108 {
 109         pgd_t *pgd;
 110         pud_t *pud;
 111         pmd_t *pmd;
 112         int pgd_idx, pmd_idx;
 113         unsigned long vaddr;
 114
 115         vaddr = start;
 116         pgd_idx = pgd_index(vaddr);
 117         pmd_idx = pmd_index(vaddr);
 118         pgd = pgd_base + pgd_idx;
 119
 120         for ( ; (pgd_idx < PTRS_PER_PGD) && (vaddr != end); pgd++, pgd_idx++) {
 121                 if (pgd_none(*pgd))
 122                         one_md_table_init(pgd);
 123                 pud = pud_offset(pgd, vaddr);
 124                 pmd = pmd_offset(pud, vaddr);
 125                 for (; (pmd_idx < PTRS_PER_PMD) && (vaddr != end); pmd++, pmd_idx++) {
 126                         if (pmd_none(*pmd))
 127                                 one_page_table_init(pmd);
 128
 129                         vaddr += PMD_SIZE;
 130                 }
 131                 pmd_idx = 0;
 132         }
 133 }
 134
 135 static inline int is_kernel_text(unsigned long addr)
 136 {
 137         if (addr >= PAGE_OFFSET && addr <= (unsigned long)__init_end)
 138                 return 1;
 139         return 0;
 140 }
 141
 142 /*
 143  * This maps the physical memory to kernel virtual address space, a total
 144  * of max_low_pfn pages, by creating page tables starting from address
 145  * PAGE_OFFSET.
 146  */
 147 static void __init kernel_physical_mapping_init(pgd_t *pgd_base)
 148 {
 149         unsigned long pfn;
 150         pgd_t *pgd;
 151         pmd_t *pmd;
 152         pte_t *pte;
 153         int pgd_idx, pmd_idx, pte_ofs;
 154
 155         pgd_idx = pgd_index(PAGE_OFFSET);
 156         pgd = pgd_base + pgd_idx;
 157         pfn = 0;
 158
 159         for (; pgd_idx < PTRS_PER_PGD; pgd++, pgd_idx++) {
 160                 pmd = one_md_table_init(pgd);
 161                 if (pfn >= max_low_pfn)
 162                         continue;
 163                 for (pmd_idx = 0; pmd_idx < PTRS_PER_PMD && pfn < max_low_pfn; pmd++, pmd_idx++) {
 164                         unsigned int address = pfn * PAGE_SIZE + PAGE_OFFSET;
 165
 166                         /* Map with big pages if possible, otherwise create normal page tables. */
 167                         if (cpu_has_pse) {
 168                                 unsigned int address2 = (pfn + PTRS_PER_PTE - 1) * PAGE_SIZE + PAGE_OFFSET + PAGE_SIZE-1;
 169
 170                                 if (is_kernel_text(address) || is_kernel_text(address2))
 171                                         set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE_EXEC));
 172                                 else
 173                                         set_pmd(pmd, pfn_pmd(pfn, PAGE_KERNEL_LARGE));
 174                                 pfn += PTRS_PER_PTE;
 175                         } else {
 176                                 pte = one_page_table_init(pmd);
 177
 178                                 for (pte_ofs = 0; pte_ofs < PTRS_PER_PTE && pfn < max_low_pfn; pte++, pfn++, pte_ofs++) {
 179                                                 if (is_kernel_text(address))
 180                                                         set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC));
 181                                                 else
 182                                                         set_pte(pte, pfn_pte(pfn, PAGE_KERNEL));
 183                                 }
 184                         }
 185                 }
 186         }
 187 }
 188
 189 static inline int page_kills_ppro(unsigned long pagenr)
 190 {
 191         if (pagenr >= 0x70000 && pagenr <= 0x7003F)
 192                 return 1;
 193         return 0;
 194 }
 195
 196 extern int is_available_memory(efi_memory_desc_t *);
 197
 198 int page_is_ram(unsigned long pagenr)
 199 {
 200         int i;
 201         unsigned long addr, end;
 202
 203         if (efi_enabled) {
 204                 efi_memory_desc_t *md;
 205                 void *p;
 206
 207                 for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
 208                         md = p;
 209                         if (!is_available_memory(md))
 210                                 continue;
 211                         addr = (md->phys_addr+PAGE_SIZE-1) >> PAGE_SHIFT;
 212                         end = (md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT)) >> PAGE_SHIFT;
 213
 214                         if ((pagenr >= addr) && (pagenr < end))
 215                                 return 1;
 216                 }
 217                 return 0;
 218         }
 219
 220         for (i = 0; i < e820.nr_map; i++) {
 221
 222                 if (e820.map[i].type != E820_RAM)       /* not usable memory */
 223                         continue;
 224                 /*
 225                  *      !!!FIXME!!! Some BIOSen report areas as RAM that
 226                  *      are not. Notably the 640->1Mb area. We need a sanity
 227                  *      check here.
 228                  */
 229                 addr = (e820.map[i].addr+PAGE_SIZE-1) >> PAGE_SHIFT;
 230                 end = (e820.map[i].addr+e820.map[i].size) >> PAGE_SHIFT;
 231                 if  ((pagenr >= addr) && (pagenr < end))
 232                         return 1;
 233         }
 234         return 0;
 235 }
 236
 237 #ifdef CONFIG_HIGHMEM
 238 pte_t *kmap_pte;
 239 pgprot_t kmap_prot;
 240
 241 #define kmap_get_fixmap_pte(vaddr)                                      \
 242         pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), vaddr), (vaddr)), (vaddr))
 243
 244 static void __init kmap_init(void)
 245 {
 246         unsigned long kmap_vstart;
 247
 248         /* cache the first kmap pte */
 249         kmap_vstart = __fix_to_virt(FIX_KMAP_BEGIN);
 250         kmap_pte = kmap_get_fixmap_pte(kmap_vstart);
 251
 252         kmap_prot = PAGE_KERNEL;
 253 }
 254
 255 static void __init permanent_kmaps_init(pgd_t *pgd_base)
 256 {
 257         pgd_t *pgd;
 258         pud_t *pud;
 259         pmd_t *pmd;
 260         pte_t *pte;
 261         unsigned long vaddr;
 262
 263         vaddr = PKMAP_BASE;
 264         page_table_range_init(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP, pgd_base);
 265
 266         pgd = swapper_pg_dir + pgd_index(vaddr);
 267         pud = pud_offset(pgd, vaddr);
 268         pmd = pmd_offset(pud, vaddr);
 269         pte = pte_offset_kernel(pmd, vaddr);
 270         pkmap_page_table = pte;
 271 }
 272
 273 static void __meminit free_new_highpage(struct page *page)
 274 {
 275         init_page_count(page);
 276         __free_page(page);
 277         totalhigh_pages++;
 278 }
 279
 280 void __init add_one_highpage_init(struct page *page, int pfn, int bad_ppro)
 281 {
 282         if (page_is_ram(pfn) && !(bad_ppro && page_kills_ppro(pfn))) {
 283                 ClearPageReserved(page);
 284                 free_new_highpage(page);
 285         } else
 286                 SetPageReserved(page);
 287 }
 288
 289 static int add_one_highpage_hotplug(struct page *page, unsigned long pfn)
 290 {
 291         free_new_highpage(page);
 292         totalram_pages++;
 293 #ifdef CONFIG_FLATMEM
 294         max_mapnr = max(pfn, max_mapnr);
 295 #endif
 296         num_physpages++;
 297         return 0;
 298 }
 299
 300 /*
 301  * Not currently handling the NUMA case.
 302  * Assuming single node and all memory that
 303  * has been added dynamically that would be
 304  * onlined here is in HIGHMEM
 305  */
 306 void online_page(struct page *page)
 307 {
 308         ClearPageReserved(page);
 309         add_one_highpage_hotplug(page, page_to_pfn(page));
 310 }
 311
 312
 313 #ifdef CONFIG_NUMA
 314 extern void set_highmem_pages_init(int);
 315 #else
 316 static void __init set_highmem_pages_init(int bad_ppro)
 317 {
 318         int pfn;
 319         for (pfn = highstart_pfn; pfn < highend_pfn; pfn++)
 320                 add_one_highpage_init(pfn_to_page(pfn), pfn, bad_ppro);
 321         totalram_pages += totalhigh_pages;
 322 }
 323 #endif /* CONFIG_FLATMEM */
 324
 325 #else
 326 #define kmap_init() do { } while (0)
 327 #define permanent_kmaps_init(pgd_base) do { } while (0)
 328 #define set_highmem_pages_init(bad_ppro) do { } while (0)
 329 #endif /* CONFIG_HIGHMEM */
 330
 331 unsigned long long __PAGE_KERNEL = _PAGE_KERNEL;
 332 EXPORT_SYMBOL(__PAGE_KERNEL);
 333 unsigned long long __PAGE_KERNEL_EXEC = _PAGE_KERNEL_EXEC;
 334
 335 #ifdef CONFIG_NUMA
 336 extern void __init remap_numa_kva(void);
 337 #else
 338 #define remap_numa_kva() do {} while (0)
 339 #endif
 340
 341 static void __init pagetable_init (void)
 342 {
 343         unsigned long vaddr;
 344         pgd_t *pgd_base = swapper_pg_dir;
 345
 346 #ifdef CONFIG_X86_PAE
 347         int i;
 348         /* Init entries of the first-level page table to the zero page */
 349         for (i = 0; i < PTRS_PER_PGD; i++)
 350                 set_pgd(pgd_base + i, __pgd(__pa(empty_zero_page) | _PAGE_PRESENT));
 351 #endif
 352
 353         /* Enable PSE if available */
 354         if (cpu_has_pse) {
 355                 set_in_cr4(X86_CR4_PSE);
 356         }
 357
 358         /* Enable PGE if available */
 359         if (cpu_has_pge) {
 360                 set_in_cr4(X86_CR4_PGE);
 361                 __PAGE_KERNEL |= _PAGE_GLOBAL;
 362                 __PAGE_KERNEL_EXEC |= _PAGE_GLOBAL;
 363         }
 364
 365         kernel_physical_mapping_init(pgd_base);
 366         remap_numa_kva();
 367
 368         /*
 369          * Fixed mappings, only the page table structure has to be
 370          * created - mappings will be set by set_fixmap():
 371          */
 372         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 373         page_table_range_init(vaddr, 0, pgd_base);
 374
 375         permanent_kmaps_init(pgd_base);
 376
 377 #ifdef CONFIG_X86_PAE
 378         /*
 379          * Add low memory identity-mappings - SMP needs it when
 380          * starting up on an AP from real-mode. In the non-PAE
 381          * case we already have these mappings through head.S.
 382          * All user-space mappings are explicitly cleared after
 383          * SMP startup.
 384          */
 385         set_pgd(&pgd_base[0], pgd_base[USER_PTRS_PER_PGD]);
 386 #endif
 387 }
 388
 389 #if defined(CONFIG_SOFTWARE_SUSPEND) || defined(CONFIG_ACPI_SLEEP)
 390 /*
 391  * Swap suspend & friends need this for resume because things like the intel-agp
 392  * driver might have split up a kernel 4MB mapping.
 393  */
 394 char __nosavedata swsusp_pg_dir[PAGE_SIZE]
 395         __attribute__ ((aligned (PAGE_SIZE)));
 396
 397 static inline void save_pg_dir(void)
 398 {
 399         memcpy(swsusp_pg_dir, swapper_pg_dir, PAGE_SIZE);
 400 }
 401 #else
 402 static inline void save_pg_dir(void)
 403 {
 404 }
 405 #endif
 406
 407 void zap_low_mappings (void)
 408 {
 409         int i;
 410
 411         save_pg_dir();
 412
 413         /*
 414          * Zap initial low-memory mappings.
 415          *
 416          * Note that "pgd_clear()" doesn't do it for
 417          * us, because pgd_clear() is a no-op on i386.
 418          */
 419         for (i = 0; i < USER_PTRS_PER_PGD; i++)
 420 #ifdef CONFIG_X86_PAE
 421                 set_pgd(swapper_pg_dir+i, __pgd(1 + __pa(empty_zero_page)));
 422 #else
 423                 set_pgd(swapper_pg_dir+i, __pgd(0));
 424 #endif
 425         flush_tlb_all();
 426 }
 427
 428 static int disable_nx __initdata = 0;
 429 u64 __supported_pte_mask __read_mostly = ~_PAGE_NX;
 430
 431 /*
 432  * noexec = on|off
 433  *
 434  * Control non executable mappings.
 435  *
 436  * on      Enable
 437  * off     Disable
 438  */
 439 void __init noexec_setup(const char *str)
 440 {
 441         if (!strncmp(str, "on",2) && cpu_has_nx) {
 442                 __supported_pte_mask |= _PAGE_NX;
 443                 disable_nx = 0;
 444         } else if (!strncmp(str,"off",3)) {
 445                 disable_nx = 1;
 446                 __supported_pte_mask &= ~_PAGE_NX;
 447         }
 448 }
 449
 450 int nx_enabled = 0;
 451 #ifdef CONFIG_X86_PAE
 452
 453 static void __init set_nx(void)
 454 {
 455         unsigned int v[4], l, h;
 456
 457         if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {
 458                 cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);
 459                 if ((v[3] & (1 << 20)) && !disable_nx) {
 460                         rdmsr(MSR_EFER, l, h);
 461                         l |= EFER_NX;
 462                         wrmsr(MSR_EFER, l, h);
 463                         nx_enabled = 1;
 464                         __supported_pte_mask |= _PAGE_NX;
 465                 }
 466         }
 467 }
 468
 469 /*
 470  * Enables/disables executability of a given kernel page and
 471  * returns the previous setting.
 472  */
 473 int __init set_kernel_exec(unsigned long vaddr, int enable)
 474 {
 475         pte_t *pte;
 476         int ret = 1;
 477
 478         if (!nx_enabled)
 479                 goto out;
 480
 481         pte = lookup_address(vaddr);
 482         BUG_ON(!pte);
 483
 484         if (!pte_exec_kernel(*pte))
 485                 ret = 0;
 486
 487         if (enable)
 488                 pte->pte_high &= ~(1 << (_PAGE_BIT_NX - 32));
 489         else
 490                 pte->pte_high |= 1 << (_PAGE_BIT_NX - 32);
 491         __flush_tlb_all();
 492 out:
 493         return ret;
 494 }
 495
 496 #endif
 497
 498 /*
 499  * paging_init() sets up the page tables - note that the first 8MB are
 500  * already mapped by head.S.
 501  *
 502  * This routines also unmaps the page at virtual kernel address 0, so
 503  * that we can trap those pesky NULL-reference errors in the kernel.
 504  */
 505 void __init paging_init(void)
 506 {
 507 #ifdef CONFIG_X86_PAE
 508         set_nx();
 509         if (nx_enabled)
 510                 printk("NX (Execute Disable) protection: active\n");
 511 #endif
 512
 513         pagetable_init();
 514
 515         load_cr3(swapper_pg_dir);
 516
 517 #ifdef CONFIG_X86_PAE
 518         /*
 519          * We will bail out later - printk doesn't work right now so
 520          * the user would just see a hanging kernel.
 521          */
 522         if (cpu_has_pae)
 523                 set_in_cr4(X86_CR4_PAE);
 524 #endif
 525         __flush_tlb_all();
 526
 527         kmap_init();
 528 }
 529
 530 /*
 531  * Test if the WP bit works in supervisor mode. It isn't supported on 386's
 532  * and also on some strange 486's (NexGen etc.). All 586+'s are OK. This
 533  * used to involve black magic jumps to work around some nasty CPU bugs,
 534  * but fortunately the switch to using exceptions got rid of all that.
 535  */
 536
 537 static void __init test_wp_bit(void)
 538 {
 539         printk("Checking if this processor honours the WP bit even in supervisor mode... ");
 540
 541         /* Any page-aligned address will do, the test is non-destructive */
 542         __set_fixmap(FIX_WP_TEST, __pa(&swapper_pg_dir), PAGE_READONLY);
 543         boot_cpu_data.wp_works_ok = do_test_wp_bit();
 544         clear_fixmap(FIX_WP_TEST);
 545
 546         if (!boot_cpu_data.wp_works_ok) {
 547                 printk("No.\n");
 548 #ifdef CONFIG_X86_WP_WORKS_OK
 549                 panic("This kernel doesn't support CPU's with broken WP. Recompile it for a 386!");
 550 #endif
 551         } else {
 552                 printk("Ok.\n");
 553         }
 554 }
 555
 556 static void __init set_max_mapnr_init(void)
 557 {
 558 #ifdef CONFIG_HIGHMEM
 559         num_physpages = highend_pfn;
 560 #else
 561         num_physpages = max_low_pfn;
 562 #endif
 563 #ifdef CONFIG_FLATMEM
 564         max_mapnr = num_physpages;
 565 #endif
 566 }
 567
 568 static struct kcore_list kcore_mem, kcore_vmalloc;
 569
 570 void __init mem_init(void)
 571 {
 572         extern int ppro_with_ram_bug(void);
 573         int codesize, reservedpages, datasize, initsize;
 574         int tmp;
 575         int bad_ppro;
 576
 577 #ifdef CONFIG_FLATMEM
 578         if (!mem_map)
 579                 BUG();
 580 #endif
 581
 582         bad_ppro = ppro_with_ram_bug();
 583
 584 #ifdef CONFIG_HIGHMEM
 585         /* check that fixmap and pkmap do not overlap */
 586         if (PKMAP_BASE+LAST_PKMAP*PAGE_SIZE >= FIXADDR_START) {
 587                 printk(KERN_ERR "fixmap and kmap areas overlap - this will crash\n");
 588                 printk(KERN_ERR "pkstart: %lxh pkend: %lxh fixstart %lxh\n",
 589                                 PKMAP_BASE, PKMAP_BASE+LAST_PKMAP*PAGE_SIZE, FIXADDR_START);
 590                 BUG();
 591         }
 592 #endif
 593
 594         set_max_mapnr_init();
 595
 596 #ifdef CONFIG_HIGHMEM
 597         high_memory = (void *) __va(highstart_pfn * PAGE_SIZE - 1) + 1;
 598 #else
 599         high_memory = (void *) __va(max_low_pfn * PAGE_SIZE - 1) + 1;
 600 #endif
 601
 602         /* this will put all low memory onto the freelists */
 603         totalram_pages += free_all_bootmem();
 604
 605         reservedpages = 0;
 606         for (tmp = 0; tmp < max_low_pfn; tmp++)
 607                 /*
 608                  * Only count reserved RAM pages
 609                  */
 610                 if (page_is_ram(tmp) && PageReserved(pfn_to_page(tmp)))
 611                         reservedpages++;
 612
 613         set_highmem_pages_init(bad_ppro);
 614
 615         codesize =  (unsigned long) &_etext - (unsigned long) &_text;
 616         datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
 617         initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
 618
 619         kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT);
 620         kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 621                    VMALLOC_END-VMALLOC_START);
 622
 623         printk(KERN_INFO "Memory: %luk/%luk available (%dk kernel code, %dk reserved, %dk data, %dk init, %ldk highmem)\n",
 624                 (unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
 625                 num_physpages << (PAGE_SHIFT-10),
 626                 codesize >> 10,
 627                 reservedpages << (PAGE_SHIFT-10),
 628                 datasize >> 10,
 629                 initsize >> 10,
 630                 (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10))
 631                );
 632
 633 #ifdef CONFIG_X86_PAE
 634         if (!cpu_has_pae)
 635                 panic("cannot execute a PAE-enabled kernel on a PAE-less CPU!");
 636 #endif
 637         if (boot_cpu_data.wp_works_ok < 0)
 638                 test_wp_bit();
 639
 640         /*
 641          * Subtle. SMP is doing it's boot stuff late (because it has to
 642          * fork idle threads) - but it also needs low mappings for the
 643          * protected-mode entry to work. We zap these entries only after
 644          * the WP-bit has been tested.
 645          */
 646 #ifndef CONFIG_SMP
 647         zap_low_mappings();
 648 #endif
 649 }
 650
 651 /*
 652  * this is for the non-NUMA, single node SMP system case.
 653  * Specifically, in the case of x86, we will always add
 654  * memory to the highmem for now.
 655  */
 656 #ifdef CONFIG_MEMORY_HOTPLUG
 657 #ifndef CONFIG_NEED_MULTIPLE_NODES
 658 int arch_add_memory(int nid, u64 start, u64 size)
 659 {
 660         struct pglist_data *pgdata = &contig_page_data;
 661         struct zone *zone = pgdata->node_zones + MAX_NR_ZONES-1;
 662         unsigned long start_pfn = start >> PAGE_SHIFT;
 663         unsigned long nr_pages = size >> PAGE_SHIFT;
 664
 665         return __add_pages(zone, start_pfn, nr_pages);
 666 }
 667
 668 int remove_memory(u64 start, u64 size)
 669 {
 670         return -EINVAL;
 671 }
 672 #endif
 673 #endif
 674
 675 kmem_cache_t *pgd_cache;
 676 kmem_cache_t *pmd_cache;
 677
 678 void __init pgtable_cache_init(void)
 679 {
 680         if (PTRS_PER_PMD > 1) {
 681                 pmd_cache = kmem_cache_create("pmd",
 682                                         PTRS_PER_PMD*sizeof(pmd_t),
 683                                         PTRS_PER_PMD*sizeof(pmd_t),
 684                                         0,
 685                                         pmd_ctor,
 686                                         NULL);
 687                 if (!pmd_cache)
 688                         panic("pgtable_cache_init(): cannot create pmd cache");
 689         }
 690         pgd_cache = kmem_cache_create("pgd",
 691                                 PTRS_PER_PGD*sizeof(pgd_t),
 692                                 PTRS_PER_PGD*sizeof(pgd_t),
 693                                 0,
 694                                 pgd_ctor,
 695                                 PTRS_PER_PMD == 1 ? pgd_dtor : NULL);
 696         if (!pgd_cache)
 697                 panic("pgtable_cache_init(): Cannot create pgd cache");
 698 }
 699
 700 /*
 701  * This function cannot be __init, since exceptions don't work in that
 702  * section.  Put this after the callers, so that it cannot be inlined.
 703  */
 704 static int noinline do_test_wp_bit(void)
 705 {
 706         char tmp_reg;
 707         int flag;
 708
 709         __asm__ __volatile__(
 710                 "       movb %0,%1      \n"
 711                 "1:     movb %1,%0      \n"
 712                 "       xorl %2,%2      \n"
 713                 "2:                     \n"
 714                 ".section __ex_table,\"a\"\n"
 715                 "       .align 4        \n"
 716                 "       .long 1b,2b     \n"
 717                 ".previous              \n"
 718                 :"=m" (*(char *)fix_to_virt(FIX_WP_TEST)),
 719                  "=q" (tmp_reg),
 720                  "=r" (flag)
 721                 :"2" (1)
 722                 :"memory");
 723
 724         return flag;
 725 }
 726
 727 #ifdef CONFIG_DEBUG_RODATA
 728
 729 extern char __start_rodata, __end_rodata;
 730 void mark_rodata_ro(void)
 731 {
 732         unsigned long addr = (unsigned long)&__start_rodata;
 733
 734         for (; addr < (unsigned long)&__end_rodata; addr += PAGE_SIZE)
 735                 change_page_attr(virt_to_page(addr), 1, PAGE_KERNEL_RO);
 736
 737         printk ("Write protecting the kernel read-only data: %luk\n",
 738                         (unsigned long)(&__end_rodata - &__start_rodata) >> 10);
 739
 740         /*
 741          * change_page_attr() requires a global_flush_tlb() call after it.
 742          * We do this after the printk so that if something went wrong in the
 743          * change, the printk gets out at least to give a better debug hint
 744          * of who is the culprit.
 745          */
 746         global_flush_tlb();
 747 }
 748 #endif
 749
 750 void free_init_pages(char *what, unsigned long begin, unsigned long end)
 751 {
 752         unsigned long addr;
 753
 754         for (addr = begin; addr < end; addr += PAGE_SIZE) {
 755                 ClearPageReserved(virt_to_page(addr));
 756                 init_page_count(virt_to_page(addr));
 757                 memset((void *)addr, POISON_FREE_INITMEM, PAGE_SIZE);
 758                 free_page(addr);
 759                 totalram_pages++;
 760         }
 761         printk(KERN_INFO "Freeing %s: %ldk freed\n", what, (end - begin) >> 10);
 762 }
 763
 764 void free_initmem(void)
 765 {
 766         free_init_pages("unused kernel memory",
 767                         (unsigned long)(&__init_begin),
 768                         (unsigned long)(&__init_end));
 769 }
 770
 771 #ifdef CONFIG_BLK_DEV_INITRD
 772 void free_initrd_mem(unsigned long start, unsigned long end)
 773 {
 774         free_init_pages("initrd memory", start, end);
 775 }
 776 #endif
 777