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   1 /*
   2  *  linux/arch/arm/mm/mm-armv.c
   3  *
   4  *  Copyright (C) 1998-2005 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  Page table sludge for ARM v3 and v4 processor architectures.
  11  */
  12 #include <linux/config.h>
  13 #include <linux/module.h>
  14 #include <linux/mm.h>
  15 #include <linux/init.h>
  16 #include <linux/bootmem.h>
  17 #include <linux/highmem.h>
  18 #include <linux/nodemask.h>
  19
  20 #include <asm/pgalloc.h>
  21 #include <asm/page.h>
  22 #include <asm/io.h>
  23 #include <asm/setup.h>
  24 #include <asm/tlbflush.h>
  25
  26 #include <asm/mach/map.h>
  27
  28 #define CPOLICY_UNCACHED        0
  29 #define CPOLICY_BUFFERED        1
  30 #define CPOLICY_WRITETHROUGH    2
  31 #define CPOLICY_WRITEBACK       3
  32 #define CPOLICY_WRITEALLOC      4
  33
  34 static unsigned int cachepolicy __initdata = CPOLICY_WRITEBACK;
  35 static unsigned int ecc_mask __initdata = 0;
  36 pgprot_t pgprot_kernel;
  37
  38 EXPORT_SYMBOL(pgprot_kernel);
  39
  40 pmd_t *top_pmd;
  41
  42 struct cachepolicy {
  43         const char      policy[16];
  44         unsigned int    cr_mask;
  45         unsigned int    pmd;
  46         unsigned int    pte;
  47 };
  48
  49 static struct cachepolicy cache_policies[] __initdata = {
  50         {
  51                 .policy         = "uncached",
  52                 .cr_mask        = CR_W|CR_C,
  53                 .pmd            = PMD_SECT_UNCACHED,
  54                 .pte            = 0,
  55         }, {
  56                 .policy         = "buffered",
  57                 .cr_mask        = CR_C,
  58                 .pmd            = PMD_SECT_BUFFERED,
  59                 .pte            = PTE_BUFFERABLE,
  60         }, {
  61                 .policy         = "writethrough",
  62                 .cr_mask        = 0,
  63                 .pmd            = PMD_SECT_WT,
  64                 .pte            = PTE_CACHEABLE,
  65         }, {
  66                 .policy         = "writeback",
  67                 .cr_mask        = 0,
  68                 .pmd            = PMD_SECT_WB,
  69                 .pte            = PTE_BUFFERABLE|PTE_CACHEABLE,
  70         }, {
  71                 .policy         = "writealloc",
  72                 .cr_mask        = 0,
  73                 .pmd            = PMD_SECT_WBWA,
  74                 .pte            = PTE_BUFFERABLE|PTE_CACHEABLE,
  75         }
  76 };
  77
  78 /*
  79  * These are useful for identifing cache coherency
  80  * problems by allowing the cache or the cache and
  81  * writebuffer to be turned off.  (Note: the write
  82  * buffer should not be on and the cache off).
  83  */
  84 static void __init early_cachepolicy(char **p)
  85 {
  86         int i;
  87
  88         for (i = 0; i < ARRAY_SIZE(cache_policies); i++) {
  89                 int len = strlen(cache_policies[i].policy);
  90
  91                 if (memcmp(*p, cache_policies[i].policy, len) == 0) {
  92                         cachepolicy = i;
  93                         cr_alignment &= ~cache_policies[i].cr_mask;
  94                         cr_no_alignment &= ~cache_policies[i].cr_mask;
  95                         *p += len;
  96                         break;
  97                 }
  98         }
  99         if (i == ARRAY_SIZE(cache_policies))
 100                 printk(KERN_ERR "ERROR: unknown or unsupported cache policy\n");
 101         flush_cache_all();
 102         set_cr(cr_alignment);
 103 }
 104
 105 static void __init early_nocache(char **__unused)
 106 {
 107         char *p = "buffered";
 108         printk(KERN_WARNING "nocache is deprecated; use cachepolicy=%s\n", p);
 109         early_cachepolicy(&p);
 110 }
 111
 112 static void __init early_nowrite(char **__unused)
 113 {
 114         char *p = "uncached";
 115         printk(KERN_WARNING "nowb is deprecated; use cachepolicy=%s\n", p);
 116         early_cachepolicy(&p);
 117 }
 118
 119 static void __init early_ecc(char **p)
 120 {
 121         if (memcmp(*p, "on", 2) == 0) {
 122                 ecc_mask = PMD_PROTECTION;
 123                 *p += 2;
 124         } else if (memcmp(*p, "off", 3) == 0) {
 125                 ecc_mask = 0;
 126                 *p += 3;
 127         }
 128 }
 129
 130 __early_param("nocache", early_nocache);
 131 __early_param("nowb", early_nowrite);
 132 __early_param("cachepolicy=", early_cachepolicy);
 133 __early_param("ecc=", early_ecc);
 134
 135 static int __init noalign_setup(char *__unused)
 136 {
 137         cr_alignment &= ~CR_A;
 138         cr_no_alignment &= ~CR_A;
 139         set_cr(cr_alignment);
 140         return 1;
 141 }
 142
 143 __setup("noalign", noalign_setup);
 144
 145 #define FIRST_KERNEL_PGD_NR     (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
 146
 147 static inline pmd_t *pmd_off(pgd_t *pgd, unsigned long virt)
 148 {
 149         return pmd_offset(pgd, virt);
 150 }
 151
 152 static inline pmd_t *pmd_off_k(unsigned long virt)
 153 {
 154         return pmd_off(pgd_offset_k(virt), virt);
 155 }
 156
 157 /*
 158  * need to get a 16k page for level 1
 159  */
 160 pgd_t *get_pgd_slow(struct mm_struct *mm)
 161 {
 162         pgd_t *new_pgd, *init_pgd;
 163         pmd_t *new_pmd, *init_pmd;
 164         pte_t *new_pte, *init_pte;
 165
 166         new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 2);
 167         if (!new_pgd)
 168                 goto no_pgd;
 169
 170         memzero(new_pgd, FIRST_KERNEL_PGD_NR * sizeof(pgd_t));
 171
 172         /*
 173          * Copy over the kernel and IO PGD entries
 174          */
 175         init_pgd = pgd_offset_k(0);
 176         memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
 177                        (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
 178
 179         clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
 180
 181         if (!vectors_high()) {
 182                 /*
 183                  * On ARM, first page must always be allocated since it
 184                  * contains the machine vectors.
 185                  */
 186                 new_pmd = pmd_alloc(mm, new_pgd, 0);
 187                 if (!new_pmd)
 188                         goto no_pmd;
 189
 190                 new_pte = pte_alloc_map(mm, new_pmd, 0);
 191                 if (!new_pte)
 192                         goto no_pte;
 193
 194                 init_pmd = pmd_offset(init_pgd, 0);
 195                 init_pte = pte_offset_map_nested(init_pmd, 0);
 196                 set_pte(new_pte, *init_pte);
 197                 pte_unmap_nested(init_pte);
 198                 pte_unmap(new_pte);
 199         }
 200
 201         return new_pgd;
 202
 203 no_pte:
 204         pmd_free(new_pmd);
 205 no_pmd:
 206         free_pages((unsigned long)new_pgd, 2);
 207 no_pgd:
 208         return NULL;
 209 }
 210
 211 void free_pgd_slow(pgd_t *pgd)
 212 {
 213         pmd_t *pmd;
 214         struct page *pte;
 215
 216         if (!pgd)
 217                 return;
 218
 219         /* pgd is always present and good */
 220         pmd = pmd_off(pgd, 0);
 221         if (pmd_none(*pmd))
 222                 goto free;
 223         if (pmd_bad(*pmd)) {
 224                 pmd_ERROR(*pmd);
 225                 pmd_clear(pmd);
 226                 goto free;
 227         }
 228
 229         pte = pmd_page(*pmd);
 230         pmd_clear(pmd);
 231         dec_page_state(nr_page_table_pages);
 232         pte_lock_deinit(pte);
 233         pte_free(pte);
 234         pmd_free(pmd);
 235 free:
 236         free_pages((unsigned long) pgd, 2);
 237 }
 238
 239 /*
 240  * Create a SECTION PGD between VIRT and PHYS in domain
 241  * DOMAIN with protection PROT.  This operates on half-
 242  * pgdir entry increments.
 243  */
 244 static inline void
 245 alloc_init_section(unsigned long virt, unsigned long phys, int prot)
 246 {
 247         pmd_t *pmdp = pmd_off_k(virt);
 248
 249         if (virt & (1 << 20))
 250                 pmdp++;
 251
 252         *pmdp = __pmd(phys | prot);
 253         flush_pmd_entry(pmdp);
 254 }
 255
 256 /*
 257  * Create a SUPER SECTION PGD between VIRT and PHYS with protection PROT
 258  */
 259 static inline void
 260 alloc_init_supersection(unsigned long virt, unsigned long phys, int prot)
 261 {
 262         int i;
 263
 264         for (i = 0; i < 16; i += 1) {
 265                 alloc_init_section(virt, phys, prot | PMD_SECT_SUPER);
 266
 267                 virt += (PGDIR_SIZE / 2);
 268         }
 269 }
 270
 271 /*
 272  * Add a PAGE mapping between VIRT and PHYS in domain
 273  * DOMAIN with protection PROT.  Note that due to the
 274  * way we map the PTEs, we must allocate two PTE_SIZE'd
 275  * blocks - one for the Linux pte table, and one for
 276  * the hardware pte table.
 277  */
 278 static inline void
 279 alloc_init_page(unsigned long virt, unsigned long phys, unsigned int prot_l1, pgprot_t prot)
 280 {
 281         pmd_t *pmdp = pmd_off_k(virt);
 282         pte_t *ptep;
 283
 284         if (pmd_none(*pmdp)) {
 285                 ptep = alloc_bootmem_low_pages(2 * PTRS_PER_PTE *
 286                                                sizeof(pte_t));
 287
 288                 __pmd_populate(pmdp, __pa(ptep) | prot_l1);
 289         }
 290         ptep = pte_offset_kernel(pmdp, virt);
 291
 292         set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, prot));
 293 }
 294
 295 struct mem_types {
 296         unsigned int    prot_pte;
 297         unsigned int    prot_l1;
 298         unsigned int    prot_sect;
 299         unsigned int    domain;
 300 };
 301
 302 static struct mem_types mem_types[] __initdata = {
 303         [MT_DEVICE] = {
 304                 .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
 305                                 L_PTE_WRITE,
 306                 .prot_l1   = PMD_TYPE_TABLE,
 307                 .prot_sect = PMD_TYPE_SECT | PMD_SECT_UNCACHED |
 308                                 PMD_SECT_AP_WRITE,
 309                 .domain    = DOMAIN_IO,
 310         },
 311         [MT_CACHECLEAN] = {
 312                 .prot_sect = PMD_TYPE_SECT,
 313                 .domain    = DOMAIN_KERNEL,
 314         },
 315         [MT_MINICLEAN] = {
 316                 .prot_sect = PMD_TYPE_SECT | PMD_SECT_MINICACHE,
 317                 .domain    = DOMAIN_KERNEL,
 318         },
 319         [MT_LOW_VECTORS] = {
 320                 .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
 321                                 L_PTE_EXEC,
 322                 .prot_l1   = PMD_TYPE_TABLE,
 323                 .domain    = DOMAIN_USER,
 324         },
 325         [MT_HIGH_VECTORS] = {
 326                 .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
 327                                 L_PTE_USER | L_PTE_EXEC,
 328                 .prot_l1   = PMD_TYPE_TABLE,
 329                 .domain    = DOMAIN_USER,
 330         },
 331         [MT_MEMORY] = {
 332                 .prot_sect = PMD_TYPE_SECT | PMD_SECT_AP_WRITE,
 333                 .domain    = DOMAIN_KERNEL,
 334         },
 335         [MT_ROM] = {
 336                 .prot_sect = PMD_TYPE_SECT,
 337                 .domain    = DOMAIN_KERNEL,
 338         },
 339         [MT_IXP2000_DEVICE] = { /* IXP2400 requires XCB=101 for on-chip I/O */
 340                 .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
 341                                 L_PTE_WRITE,
 342                 .prot_l1   = PMD_TYPE_TABLE,
 343                 .prot_sect = PMD_TYPE_SECT | PMD_SECT_UNCACHED |
 344                                 PMD_SECT_AP_WRITE | PMD_SECT_BUFFERABLE |
 345                                 PMD_SECT_TEX(1),
 346                 .domain    = DOMAIN_IO,
 347         }
 348 };
 349
 350 /*
 351  * Adjust the PMD section entries according to the CPU in use.
 352  */
 353 void __init build_mem_type_table(void)
 354 {
 355         struct cachepolicy *cp;
 356         unsigned int cr = get_cr();
 357         unsigned int user_pgprot, kern_pgprot;
 358         int cpu_arch = cpu_architecture();
 359         int i;
 360
 361 #if defined(CONFIG_CPU_DCACHE_DISABLE)
 362         if (cachepolicy > CPOLICY_BUFFERED)
 363                 cachepolicy = CPOLICY_BUFFERED;
 364 #elif defined(CONFIG_CPU_DCACHE_WRITETHROUGH)
 365         if (cachepolicy > CPOLICY_WRITETHROUGH)
 366                 cachepolicy = CPOLICY_WRITETHROUGH;
 367 #endif
 368         if (cpu_arch < CPU_ARCH_ARMv5) {
 369                 if (cachepolicy >= CPOLICY_WRITEALLOC)
 370                         cachepolicy = CPOLICY_WRITEBACK;
 371                 ecc_mask = 0;
 372         }
 373
 374         if (cpu_arch <= CPU_ARCH_ARMv5TEJ) {
 375                 for (i = 0; i < ARRAY_SIZE(mem_types); i++) {
 376                         if (mem_types[i].prot_l1)
 377                                 mem_types[i].prot_l1 |= PMD_BIT4;
 378                         if (mem_types[i].prot_sect)
 379                                 mem_types[i].prot_sect |= PMD_BIT4;
 380                 }
 381         }
 382
 383         cp = &cache_policies[cachepolicy];
 384         kern_pgprot = user_pgprot = cp->pte;
 385
 386         /*
 387          * ARMv6 and above have extended page tables.
 388          */
 389         if (cpu_arch >= CPU_ARCH_ARMv6 && (cr & CR_XP)) {
 390                 /*
 391                  * bit 4 becomes XN which we must clear for the
 392                  * kernel memory mapping.
 393                  */
 394                 mem_types[MT_MEMORY].prot_sect &= ~PMD_BIT4;
 395                 mem_types[MT_ROM].prot_sect &= ~PMD_BIT4;
 396
 397                 /*
 398                  * Mark cache clean areas and XIP ROM read only
 399                  * from SVC mode and no access from userspace.
 400                  */
 401                 mem_types[MT_ROM].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
 402                 mem_types[MT_MINICLEAN].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
 403                 mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
 404
 405                 /*
 406                  * Mark the device area as "shared device"
 407                  */
 408                 mem_types[MT_DEVICE].prot_pte |= L_PTE_BUFFERABLE;
 409                 mem_types[MT_DEVICE].prot_sect |= PMD_SECT_BUFFERED;
 410
 411                 /*
 412                  * User pages need to be mapped with the ASID
 413                  * (iow, non-global)
 414                  */
 415                 user_pgprot |= L_PTE_ASID;
 416
 417 #ifdef CONFIG_SMP
 418                 /*
 419                  * Mark memory with the "shared" attribute for SMP systems
 420                  */
 421                 user_pgprot |= L_PTE_SHARED;
 422                 kern_pgprot |= L_PTE_SHARED;
 423                 mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
 424 #endif
 425         }
 426
 427         for (i = 0; i < 16; i++) {
 428                 unsigned long v = pgprot_val(protection_map[i]);
 429                 v = (v & ~(L_PTE_BUFFERABLE|L_PTE_CACHEABLE)) | user_pgprot;
 430                 protection_map[i] = __pgprot(v);
 431         }
 432
 433         mem_types[MT_LOW_VECTORS].prot_pte |= kern_pgprot;
 434         mem_types[MT_HIGH_VECTORS].prot_pte |= kern_pgprot;
 435
 436         if (cpu_arch >= CPU_ARCH_ARMv5) {
 437 #ifndef CONFIG_SMP
 438                 /*
 439                  * Only use write-through for non-SMP systems
 440                  */
 441                 mem_types[MT_LOW_VECTORS].prot_pte &= ~L_PTE_BUFFERABLE;
 442                 mem_types[MT_HIGH_VECTORS].prot_pte &= ~L_PTE_BUFFERABLE;
 443 #endif
 444         } else {
 445                 mem_types[MT_MINICLEAN].prot_sect &= ~PMD_SECT_TEX(1);
 446         }
 447
 448         pgprot_kernel = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG |
 449                                  L_PTE_DIRTY | L_PTE_WRITE |
 450                                  L_PTE_EXEC | kern_pgprot);
 451
 452         mem_types[MT_LOW_VECTORS].prot_l1 |= ecc_mask;
 453         mem_types[MT_HIGH_VECTORS].prot_l1 |= ecc_mask;
 454         mem_types[MT_MEMORY].prot_sect |= ecc_mask | cp->pmd;
 455         mem_types[MT_ROM].prot_sect |= cp->pmd;
 456
 457         switch (cp->pmd) {
 458         case PMD_SECT_WT:
 459                 mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_WT;
 460                 break;
 461         case PMD_SECT_WB:
 462         case PMD_SECT_WBWA:
 463                 mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_WB;
 464                 break;
 465         }
 466         printk("Memory policy: ECC %sabled, Data cache %s\n",
 467                 ecc_mask ? "en" : "dis", cp->policy);
 468 }
 469
 470 #define vectors_base()  (vectors_high() ? 0xffff0000 : 0)
 471
 472 /*
 473  * Create the page directory entries and any necessary
 474  * page tables for the mapping specified by `md'.  We
 475  * are able to cope here with varying sizes and address
 476  * offsets, and we take full advantage of sections and
 477  * supersections.
 478  */
 479 void __init create_mapping(struct map_desc *md)
 480 {
 481         unsigned long virt, length;
 482         int prot_sect, prot_l1, domain;
 483         pgprot_t prot_pte;
 484         unsigned long off = (u32)__pfn_to_phys(md->pfn);
 485
 486         if (md->virtual != vectors_base() && md->virtual < TASK_SIZE) {
 487                 printk(KERN_WARNING "BUG: not creating mapping for "
 488                        "0x%08llx at 0x%08lx in user region\n",
 489                        __pfn_to_phys((u64)md->pfn), md->virtual);
 490                 return;
 491         }
 492
 493         if ((md->type == MT_DEVICE || md->type == MT_ROM) &&
 494             md->virtual >= PAGE_OFFSET && md->virtual < VMALLOC_END) {
 495                 printk(KERN_WARNING "BUG: mapping for 0x%08llx at 0x%08lx "
 496                        "overlaps vmalloc space\n",
 497                        __pfn_to_phys((u64)md->pfn), md->virtual);
 498         }
 499
 500         domain    = mem_types[md->type].domain;
 501         prot_pte  = __pgprot(mem_types[md->type].prot_pte);
 502         prot_l1   = mem_types[md->type].prot_l1 | PMD_DOMAIN(domain);
 503         prot_sect = mem_types[md->type].prot_sect | PMD_DOMAIN(domain);
 504
 505         /*
 506          * Catch 36-bit addresses
 507          */
 508         if(md->pfn >= 0x100000) {
 509                 if(domain) {
 510                         printk(KERN_ERR "MM: invalid domain in supersection "
 511                                 "mapping for 0x%08llx at 0x%08lx\n",
 512                                 __pfn_to_phys((u64)md->pfn), md->virtual);
 513                         return;
 514                 }
 515                 if((md->virtual | md->length | __pfn_to_phys(md->pfn))
 516                         & ~SUPERSECTION_MASK) {
 517                         printk(KERN_ERR "MM: cannot create mapping for "
 518                                 "0x%08llx at 0x%08lx invalid alignment\n",
 519                                 __pfn_to_phys((u64)md->pfn), md->virtual);
 520                         return;
 521                 }
 522
 523                 /*
 524                  * Shift bits [35:32] of address into bits [23:20] of PMD
 525                  * (See ARMv6 spec).
 526                  */
 527                 off |= (((md->pfn >> (32 - PAGE_SHIFT)) & 0xF) << 20);
 528         }
 529
 530         virt   = md->virtual;
 531         off   -= virt;
 532         length = md->length;
 533
 534         if (mem_types[md->type].prot_l1 == 0 &&
 535             (virt & 0xfffff || (virt + off) & 0xfffff || (virt + length) & 0xfffff)) {
 536                 printk(KERN_WARNING "BUG: map for 0x%08lx at 0x%08lx can not "
 537                        "be mapped using pages, ignoring.\n",
 538                        __pfn_to_phys(md->pfn), md->virtual);
 539                 return;
 540         }
 541
 542         while ((virt & 0xfffff || (virt + off) & 0xfffff) && length >= PAGE_SIZE) {
 543                 alloc_init_page(virt, virt + off, prot_l1, prot_pte);
 544
 545                 virt   += PAGE_SIZE;
 546                 length -= PAGE_SIZE;
 547         }
 548
 549         /* N.B. ARMv6 supersections are only defined to work with domain 0.
 550          *      Since domain assignments can in fact be arbitrary, the
 551          *      'domain == 0' check below is required to insure that ARMv6
 552          *      supersections are only allocated for domain 0 regardless
 553          *      of the actual domain assignments in use.
 554          */
 555         if (cpu_architecture() >= CPU_ARCH_ARMv6 && domain == 0) {
 556                 /*
 557                  * Align to supersection boundary if !high pages.
 558                  * High pages have already been checked for proper
 559                  * alignment above and they will fail the SUPSERSECTION_MASK
 560                  * check because of the way the address is encoded into
 561                  * offset.
 562                  */
 563                 if (md->pfn <= 0x100000) {
 564                         while ((virt & ~SUPERSECTION_MASK ||
 565                                 (virt + off) & ~SUPERSECTION_MASK) &&
 566                                 length >= (PGDIR_SIZE / 2)) {
 567                                 alloc_init_section(virt, virt + off, prot_sect);
 568
 569                                 virt   += (PGDIR_SIZE / 2);
 570                                 length -= (PGDIR_SIZE / 2);
 571                         }
 572                 }
 573
 574                 while (length >= SUPERSECTION_SIZE) {
 575                         alloc_init_supersection(virt, virt + off, prot_sect);
 576
 577                         virt   += SUPERSECTION_SIZE;
 578                         length -= SUPERSECTION_SIZE;
 579                 }
 580         }
 581
 582         /*
 583          * A section mapping covers half a "pgdir" entry.
 584          */
 585         while (length >= (PGDIR_SIZE / 2)) {
 586                 alloc_init_section(virt, virt + off, prot_sect);
 587
 588                 virt   += (PGDIR_SIZE / 2);
 589                 length -= (PGDIR_SIZE / 2);
 590         }
 591
 592         while (length >= PAGE_SIZE) {
 593                 alloc_init_page(virt, virt + off, prot_l1, prot_pte);
 594
 595                 virt   += PAGE_SIZE;
 596                 length -= PAGE_SIZE;
 597         }
 598 }
 599
 600 /*
 601  * In order to soft-boot, we need to insert a 1:1 mapping in place of
 602  * the user-mode pages.  This will then ensure that we have predictable
 603  * results when turning the mmu off
 604  */
 605 void setup_mm_for_reboot(char mode)
 606 {
 607         unsigned long base_pmdval;
 608         pgd_t *pgd;
 609         int i;
 610
 611         if (current->mm && current->mm->pgd)
 612                 pgd = current->mm->pgd;
 613         else
 614                 pgd = init_mm.pgd;
 615
 616         base_pmdval = PMD_SECT_AP_WRITE | PMD_SECT_AP_READ | PMD_TYPE_SECT;
 617         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ)
 618                 base_pmdval |= PMD_BIT4;
 619
 620         for (i = 0; i < FIRST_USER_PGD_NR + USER_PTRS_PER_PGD; i++, pgd++) {
 621                 unsigned long pmdval = (i << PGDIR_SHIFT) | base_pmdval;
 622                 pmd_t *pmd;
 623
 624                 pmd = pmd_off(pgd, i << PGDIR_SHIFT);
 625                 pmd[0] = __pmd(pmdval);
 626                 pmd[1] = __pmd(pmdval + (1 << (PGDIR_SHIFT - 1)));
 627                 flush_pmd_entry(pmd);
 628         }
 629 }
 630
 631 /*
 632  * Create the architecture specific mappings
 633  */
 634 void __init iotable_init(struct map_desc *io_desc, int nr)
 635 {
 636         int i;
 637
 638         for (i = 0; i < nr; i++)
 639                 create_mapping(io_desc + i);
 640 }