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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/module.h>
  13 #include <linux/mm.h>
  14 #include <linux/init.h>
  15 #include <linux/bootmem.h>
  16 #include <linux/highmem.h>
  17 #include <linux/nodemask.h>
  18
  19 #include <asm/pgalloc.h>
  20 #include <asm/page.h>
  21 #include <asm/setup.h>
  22 #include <asm/tlbflush.h>
  23
  24 #include <asm/mach/map.h>
  25
  26 #define CPOLICY_UNCACHED        0
  27 #define CPOLICY_BUFFERED        1
  28 #define CPOLICY_WRITETHROUGH    2
  29 #define CPOLICY_WRITEBACK       3
  30 #define CPOLICY_WRITEALLOC      4
  31
  32 static unsigned int cachepolicy __initdata = CPOLICY_WRITEBACK;
  33 static unsigned int ecc_mask __initdata = 0;
  34 pgprot_t pgprot_kernel;
  35
  36 EXPORT_SYMBOL(pgprot_kernel);
  37
  38 pmd_t *top_pmd;
  39
  40 struct cachepolicy {
  41         const char      policy[16];
  42         unsigned int    cr_mask;
  43         unsigned int    pmd;
  44         unsigned int    pte;
  45 };
  46
  47 static struct cachepolicy cache_policies[] __initdata = {
  48         {
  49                 .policy         = "uncached",
  50                 .cr_mask        = CR_W|CR_C,
  51                 .pmd            = PMD_SECT_UNCACHED,
  52                 .pte            = 0,
  53         }, {
  54                 .policy         = "buffered",
  55                 .cr_mask        = CR_C,
  56                 .pmd            = PMD_SECT_BUFFERED,
  57                 .pte            = PTE_BUFFERABLE,
  58         }, {
  59                 .policy         = "writethrough",
  60                 .cr_mask        = 0,
  61                 .pmd            = PMD_SECT_WT,
  62                 .pte            = PTE_CACHEABLE,
  63         }, {
  64                 .policy         = "writeback",
  65                 .cr_mask        = 0,
  66                 .pmd            = PMD_SECT_WB,
  67                 .pte            = PTE_BUFFERABLE|PTE_CACHEABLE,
  68         }, {
  69                 .policy         = "writealloc",
  70                 .cr_mask        = 0,
  71                 .pmd            = PMD_SECT_WBWA,
  72                 .pte            = PTE_BUFFERABLE|PTE_CACHEABLE,
  73         }
  74 };
  75
  76 /*
  77  * These are useful for identifing cache coherency
  78  * problems by allowing the cache or the cache and
  79  * writebuffer to be turned off.  (Note: the write
  80  * buffer should not be on and the cache off).
  81  */
  82 static void __init early_cachepolicy(char **p)
  83 {
  84         int i;
  85
  86         for (i = 0; i < ARRAY_SIZE(cache_policies); i++) {
  87                 int len = strlen(cache_policies[i].policy);
  88
  89                 if (memcmp(*p, cache_policies[i].policy, len) == 0) {
  90                         cachepolicy = i;
  91                         cr_alignment &= ~cache_policies[i].cr_mask;
  92                         cr_no_alignment &= ~cache_policies[i].cr_mask;
  93                         *p += len;
  94                         break;
  95                 }
  96         }
  97         if (i == ARRAY_SIZE(cache_policies))
  98                 printk(KERN_ERR "ERROR: unknown or unsupported cache policy\n");
  99         flush_cache_all();
 100         set_cr(cr_alignment);
 101 }
 102
 103 static void __init early_nocache(char **__unused)
 104 {
 105         char *p = "buffered";
 106         printk(KERN_WARNING "nocache is deprecated; use cachepolicy=%s\n", p);
 107         early_cachepolicy(&p);
 108 }
 109
 110 static void __init early_nowrite(char **__unused)
 111 {
 112         char *p = "uncached";
 113         printk(KERN_WARNING "nowb is deprecated; use cachepolicy=%s\n", p);
 114         early_cachepolicy(&p);
 115 }
 116
 117 static void __init early_ecc(char **p)
 118 {
 119         if (memcmp(*p, "on", 2) == 0) {
 120                 ecc_mask = PMD_PROTECTION;
 121                 *p += 2;
 122         } else if (memcmp(*p, "off", 3) == 0) {
 123                 ecc_mask = 0;
 124                 *p += 3;
 125         }
 126 }
 127
 128 __early_param("nocache", early_nocache);
 129 __early_param("nowb", early_nowrite);
 130 __early_param("cachepolicy=", early_cachepolicy);
 131 __early_param("ecc=", early_ecc);
 132
 133 static int __init noalign_setup(char *__unused)
 134 {
 135         cr_alignment &= ~CR_A;
 136         cr_no_alignment &= ~CR_A;
 137         set_cr(cr_alignment);
 138         return 1;
 139 }
 140
 141 __setup("noalign", noalign_setup);
 142
 143 #define FIRST_KERNEL_PGD_NR     (FIRST_USER_PGD_NR + USER_PTRS_PER_PGD)
 144
 145 static inline pmd_t *pmd_off(pgd_t *pgd, unsigned long virt)
 146 {
 147         return pmd_offset(pgd, virt);
 148 }
 149
 150 static inline pmd_t *pmd_off_k(unsigned long virt)
 151 {
 152         return pmd_off(pgd_offset_k(virt), virt);
 153 }
 154
 155 /*
 156  * need to get a 16k page for level 1
 157  */
 158 pgd_t *get_pgd_slow(struct mm_struct *mm)
 159 {
 160         pgd_t *new_pgd, *init_pgd;
 161         pmd_t *new_pmd, *init_pmd;
 162         pte_t *new_pte, *init_pte;
 163
 164         new_pgd = (pgd_t *)__get_free_pages(GFP_KERNEL, 2);
 165         if (!new_pgd)
 166                 goto no_pgd;
 167
 168         memzero(new_pgd, FIRST_KERNEL_PGD_NR * sizeof(pgd_t));
 169
 170         /*
 171          * Copy over the kernel and IO PGD entries
 172          */
 173         init_pgd = pgd_offset_k(0);
 174         memcpy(new_pgd + FIRST_KERNEL_PGD_NR, init_pgd + FIRST_KERNEL_PGD_NR,
 175                        (PTRS_PER_PGD - FIRST_KERNEL_PGD_NR) * sizeof(pgd_t));
 176
 177         clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));
 178
 179         if (!vectors_high()) {
 180                 /*
 181                  * On ARM, first page must always be allocated since it
 182                  * contains the machine vectors.
 183                  */
 184                 new_pmd = pmd_alloc(mm, new_pgd, 0);
 185                 if (!new_pmd)
 186                         goto no_pmd;
 187
 188                 new_pte = pte_alloc_map(mm, new_pmd, 0);
 189                 if (!new_pte)
 190                         goto no_pte;
 191
 192                 init_pmd = pmd_offset(init_pgd, 0);
 193                 init_pte = pte_offset_map_nested(init_pmd, 0);
 194                 set_pte(new_pte, *init_pte);
 195                 pte_unmap_nested(init_pte);
 196                 pte_unmap(new_pte);
 197         }
 198
 199         return new_pgd;
 200
 201 no_pte:
 202         pmd_free(new_pmd);
 203 no_pmd:
 204         free_pages((unsigned long)new_pgd, 2);
 205 no_pgd:
 206         return NULL;
 207 }
 208
 209 void free_pgd_slow(pgd_t *pgd)
 210 {
 211         pmd_t *pmd;
 212         struct page *pte;
 213
 214         if (!pgd)
 215                 return;
 216
 217         /* pgd is always present and good */
 218         pmd = pmd_off(pgd, 0);
 219         if (pmd_none(*pmd))
 220                 goto free;
 221         if (pmd_bad(*pmd)) {
 222                 pmd_ERROR(*pmd);
 223                 pmd_clear(pmd);
 224                 goto free;
 225         }
 226
 227         pte = pmd_page(*pmd);
 228         pmd_clear(pmd);
 229         dec_zone_page_state(virt_to_page((unsigned long *)pgd), NR_PAGETABLE);
 230         pte_lock_deinit(pte);
 231         pte_free(pte);
 232         pmd_free(pmd);
 233 free:
 234         free_pages((unsigned long) pgd, 2);
 235 }
 236
 237 /*
 238  * Create a SECTION PGD between VIRT and PHYS in domain
 239  * DOMAIN with protection PROT.  This operates on half-
 240  * pgdir entry increments.
 241  */
 242 static inline void
 243 alloc_init_section(unsigned long virt, unsigned long phys, int prot)
 244 {
 245         pmd_t *pmdp = pmd_off_k(virt);
 246
 247         if (virt & (1 << 20))
 248                 pmdp++;
 249
 250         *pmdp = __pmd(phys | prot);
 251         flush_pmd_entry(pmdp);
 252 }
 253
 254 /*
 255  * Create a SUPER SECTION PGD between VIRT and PHYS with protection PROT
 256  */
 257 static inline void
 258 alloc_init_supersection(unsigned long virt, unsigned long phys, int prot)
 259 {
 260         int i;
 261
 262         for (i = 0; i < 16; i += 1) {
 263                 alloc_init_section(virt, phys, prot | PMD_SECT_SUPER);
 264
 265                 virt += (PGDIR_SIZE / 2);
 266         }
 267 }
 268
 269 /*
 270  * Add a PAGE mapping between VIRT and PHYS in domain
 271  * DOMAIN with protection PROT.  Note that due to the
 272  * way we map the PTEs, we must allocate two PTE_SIZE'd
 273  * blocks - one for the Linux pte table, and one for
 274  * the hardware pte table.
 275  */
 276 static inline void
 277 alloc_init_page(unsigned long virt, unsigned long phys, unsigned int prot_l1, pgprot_t prot)
 278 {
 279         pmd_t *pmdp = pmd_off_k(virt);
 280         pte_t *ptep;
 281
 282         if (pmd_none(*pmdp)) {
 283                 ptep = alloc_bootmem_low_pages(2 * PTRS_PER_PTE *
 284                                                sizeof(pte_t));
 285
 286                 __pmd_populate(pmdp, __pa(ptep) | prot_l1);
 287         }
 288         ptep = pte_offset_kernel(pmdp, virt);
 289
 290         set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, prot));
 291 }
 292
 293 struct mem_types {
 294         unsigned int    prot_pte;
 295         unsigned int    prot_l1;
 296         unsigned int    prot_sect;
 297         unsigned int    domain;
 298 };
 299
 300 static struct mem_types mem_types[] __initdata = {
 301         [MT_DEVICE] = {
 302                 .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
 303                                 L_PTE_WRITE,
 304                 .prot_l1   = PMD_TYPE_TABLE,
 305                 .prot_sect = PMD_TYPE_SECT | PMD_SECT_UNCACHED |
 306                                 PMD_SECT_AP_WRITE,
 307                 .domain    = DOMAIN_IO,
 308         },
 309         [MT_CACHECLEAN] = {
 310                 .prot_sect = PMD_TYPE_SECT,
 311                 .domain    = DOMAIN_KERNEL,
 312         },
 313         [MT_MINICLEAN] = {
 314                 .prot_sect = PMD_TYPE_SECT | PMD_SECT_MINICACHE,
 315                 .domain    = DOMAIN_KERNEL,
 316         },
 317         [MT_LOW_VECTORS] = {
 318                 .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
 319                                 L_PTE_EXEC,
 320                 .prot_l1   = PMD_TYPE_TABLE,
 321                 .domain    = DOMAIN_USER,
 322         },
 323         [MT_HIGH_VECTORS] = {
 324                 .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
 325                                 L_PTE_USER | L_PTE_EXEC,
 326                 .prot_l1   = PMD_TYPE_TABLE,
 327                 .domain    = DOMAIN_USER,
 328         },
 329         [MT_MEMORY] = {
 330                 .prot_sect = PMD_TYPE_SECT | PMD_SECT_AP_WRITE,
 331                 .domain    = DOMAIN_KERNEL,
 332         },
 333         [MT_ROM] = {
 334                 .prot_sect = PMD_TYPE_SECT,
 335                 .domain    = DOMAIN_KERNEL,
 336         },
 337         [MT_IXP2000_DEVICE] = { /* IXP2400 requires XCB=101 for on-chip I/O */
 338                 .prot_pte  = L_PTE_PRESENT | L_PTE_YOUNG | L_PTE_DIRTY |
 339                                 L_PTE_WRITE,
 340                 .prot_l1   = PMD_TYPE_TABLE,
 341                 .prot_sect = PMD_TYPE_SECT | PMD_SECT_UNCACHED |
 342                                 PMD_SECT_AP_WRITE | PMD_SECT_BUFFERABLE |
 343                                 PMD_SECT_TEX(1),
 344                 .domain    = DOMAIN_IO,
 345         },
 346         [MT_NONSHARED_DEVICE] = {
 347                 .prot_l1   = PMD_TYPE_TABLE,
 348                 .prot_sect = PMD_TYPE_SECT | PMD_SECT_NONSHARED_DEV |
 349                                 PMD_SECT_AP_WRITE,
 350                 .domain    = DOMAIN_IO,
 351         }
 352 };
 353
 354 /*
 355  * Adjust the PMD section entries according to the CPU in use.
 356  */
 357 void __init build_mem_type_table(void)
 358 {
 359         struct cachepolicy *cp;
 360         unsigned int cr = get_cr();
 361         unsigned int user_pgprot, kern_pgprot;
 362         int cpu_arch = cpu_architecture();
 363         int i;
 364
 365 #if defined(CONFIG_CPU_DCACHE_DISABLE)
 366         if (cachepolicy > CPOLICY_BUFFERED)
 367                 cachepolicy = CPOLICY_BUFFERED;
 368 #elif defined(CONFIG_CPU_DCACHE_WRITETHROUGH)
 369         if (cachepolicy > CPOLICY_WRITETHROUGH)
 370                 cachepolicy = CPOLICY_WRITETHROUGH;
 371 #endif
 372         if (cpu_arch < CPU_ARCH_ARMv5) {
 373                 if (cachepolicy >= CPOLICY_WRITEALLOC)
 374                         cachepolicy = CPOLICY_WRITEBACK;
 375                 ecc_mask = 0;
 376         }
 377
 378         if (cpu_arch <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale()) {
 379                 for (i = 0; i < ARRAY_SIZE(mem_types); i++) {
 380                         if (mem_types[i].prot_l1)
 381                                 mem_types[i].prot_l1 |= PMD_BIT4;
 382                         if (mem_types[i].prot_sect)
 383                                 mem_types[i].prot_sect |= PMD_BIT4;
 384                 }
 385         }
 386
 387         cp = &cache_policies[cachepolicy];
 388         kern_pgprot = user_pgprot = cp->pte;
 389
 390         /*
 391          * Enable CPU-specific coherency if supported.
 392          * (Only available on XSC3 at the moment.)
 393          */
 394         if (arch_is_coherent()) {
 395                 if (cpu_is_xsc3()) {
 396                         mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
 397                         mem_types[MT_MEMORY].prot_pte |= L_PTE_COHERENT;
 398                 }
 399         }
 400
 401         /*
 402          * ARMv6 and above have extended page tables.
 403          */
 404         if (cpu_arch >= CPU_ARCH_ARMv6 && (cr & CR_XP)) {
 405                 /*
 406                  * bit 4 becomes XN which we must clear for the
 407                  * kernel memory mapping.
 408                  */
 409                 mem_types[MT_MEMORY].prot_sect &= ~PMD_BIT4;
 410                 mem_types[MT_ROM].prot_sect &= ~PMD_BIT4;
 411
 412                 /*
 413                  * Mark cache clean areas and XIP ROM read only
 414                  * from SVC mode and no access from userspace.
 415                  */
 416                 mem_types[MT_ROM].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
 417                 mem_types[MT_MINICLEAN].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
 418                 mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
 419
 420                 /*
 421                  * Mark the device area as "shared device"
 422                  */
 423                 mem_types[MT_DEVICE].prot_pte |= L_PTE_BUFFERABLE;
 424                 mem_types[MT_DEVICE].prot_sect |= PMD_SECT_BUFFERED;
 425
 426                 /*
 427                  * User pages need to be mapped with the ASID
 428                  * (iow, non-global)
 429                  */
 430                 user_pgprot |= L_PTE_ASID;
 431
 432 #ifdef CONFIG_SMP
 433                 /*
 434                  * Mark memory with the "shared" attribute for SMP systems
 435                  */
 436                 user_pgprot |= L_PTE_SHARED;
 437                 kern_pgprot |= L_PTE_SHARED;
 438                 mem_types[MT_MEMORY].prot_sect |= PMD_SECT_S;
 439 #endif
 440         }
 441
 442         for (i = 0; i < 16; i++) {
 443                 unsigned long v = pgprot_val(protection_map[i]);
 444                 v = (v & ~(L_PTE_BUFFERABLE|L_PTE_CACHEABLE)) | user_pgprot;
 445                 protection_map[i] = __pgprot(v);
 446         }
 447
 448         mem_types[MT_LOW_VECTORS].prot_pte |= kern_pgprot;
 449         mem_types[MT_HIGH_VECTORS].prot_pte |= kern_pgprot;
 450
 451         if (cpu_arch >= CPU_ARCH_ARMv5) {
 452 #ifndef CONFIG_SMP
 453                 /*
 454                  * Only use write-through for non-SMP systems
 455                  */
 456                 mem_types[MT_LOW_VECTORS].prot_pte &= ~L_PTE_BUFFERABLE;
 457                 mem_types[MT_HIGH_VECTORS].prot_pte &= ~L_PTE_BUFFERABLE;
 458 #endif
 459         } else {
 460                 mem_types[MT_MINICLEAN].prot_sect &= ~PMD_SECT_TEX(1);
 461         }
 462
 463         pgprot_kernel = __pgprot(L_PTE_PRESENT | L_PTE_YOUNG |
 464                                  L_PTE_DIRTY | L_PTE_WRITE |
 465                                  L_PTE_EXEC | kern_pgprot);
 466
 467         mem_types[MT_LOW_VECTORS].prot_l1 |= ecc_mask;
 468         mem_types[MT_HIGH_VECTORS].prot_l1 |= ecc_mask;
 469         mem_types[MT_MEMORY].prot_sect |= ecc_mask | cp->pmd;
 470         mem_types[MT_ROM].prot_sect |= cp->pmd;
 471
 472         switch (cp->pmd) {
 473         case PMD_SECT_WT:
 474                 mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_WT;
 475                 break;
 476         case PMD_SECT_WB:
 477         case PMD_SECT_WBWA:
 478                 mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_WB;
 479                 break;
 480         }
 481         printk("Memory policy: ECC %sabled, Data cache %s\n",
 482                 ecc_mask ? "en" : "dis", cp->policy);
 483 }
 484
 485 #define vectors_base()  (vectors_high() ? 0xffff0000 : 0)
 486
 487 /*
 488  * Create the page directory entries and any necessary
 489  * page tables for the mapping specified by `md'.  We
 490  * are able to cope here with varying sizes and address
 491  * offsets, and we take full advantage of sections and
 492  * supersections.
 493  */
 494 void __init create_mapping(struct map_desc *md)
 495 {
 496         unsigned long virt, length;
 497         int prot_sect, prot_l1, domain;
 498         pgprot_t prot_pte;
 499         unsigned long off = (u32)__pfn_to_phys(md->pfn);
 500
 501         if (md->virtual != vectors_base() && md->virtual < TASK_SIZE) {
 502                 printk(KERN_WARNING "BUG: not creating mapping for "
 503                        "0x%08llx at 0x%08lx in user region\n",
 504                        __pfn_to_phys((u64)md->pfn), md->virtual);
 505                 return;
 506         }
 507
 508         if ((md->type == MT_DEVICE || md->type == MT_ROM) &&
 509             md->virtual >= PAGE_OFFSET && md->virtual < VMALLOC_END) {
 510                 printk(KERN_WARNING "BUG: mapping for 0x%08llx at 0x%08lx "
 511                        "overlaps vmalloc space\n",
 512                        __pfn_to_phys((u64)md->pfn), md->virtual);
 513         }
 514
 515         domain    = mem_types[md->type].domain;
 516         prot_pte  = __pgprot(mem_types[md->type].prot_pte);
 517         prot_l1   = mem_types[md->type].prot_l1 | PMD_DOMAIN(domain);
 518         prot_sect = mem_types[md->type].prot_sect | PMD_DOMAIN(domain);
 519
 520         /*
 521          * Catch 36-bit addresses
 522          */
 523         if(md->pfn >= 0x100000) {
 524                 if(domain) {
 525                         printk(KERN_ERR "MM: invalid domain in supersection "
 526                                 "mapping for 0x%08llx at 0x%08lx\n",
 527                                 __pfn_to_phys((u64)md->pfn), md->virtual);
 528                         return;
 529                 }
 530                 if((md->virtual | md->length | __pfn_to_phys(md->pfn))
 531                         & ~SUPERSECTION_MASK) {
 532                         printk(KERN_ERR "MM: cannot create mapping for "
 533                                 "0x%08llx at 0x%08lx invalid alignment\n",
 534                                 __pfn_to_phys((u64)md->pfn), md->virtual);
 535                         return;
 536                 }
 537
 538                 /*
 539                  * Shift bits [35:32] of address into bits [23:20] of PMD
 540                  * (See ARMv6 spec).
 541                  */
 542                 off |= (((md->pfn >> (32 - PAGE_SHIFT)) & 0xF) << 20);
 543         }
 544
 545         virt   = md->virtual;
 546         off   -= virt;
 547         length = md->length;
 548
 549         if (mem_types[md->type].prot_l1 == 0 &&
 550             (virt & 0xfffff || (virt + off) & 0xfffff || (virt + length) & 0xfffff)) {
 551                 printk(KERN_WARNING "BUG: map for 0x%08lx at 0x%08lx can not "
 552                        "be mapped using pages, ignoring.\n",
 553                        __pfn_to_phys(md->pfn), md->virtual);
 554                 return;
 555         }
 556
 557         while ((virt & 0xfffff || (virt + off) & 0xfffff) && length >= PAGE_SIZE) {
 558                 alloc_init_page(virt, virt + off, prot_l1, prot_pte);
 559
 560                 virt   += PAGE_SIZE;
 561                 length -= PAGE_SIZE;
 562         }
 563
 564         /* N.B. ARMv6 supersections are only defined to work with domain 0.
 565          *      Since domain assignments can in fact be arbitrary, the
 566          *      'domain == 0' check below is required to insure that ARMv6
 567          *      supersections are only allocated for domain 0 regardless
 568          *      of the actual domain assignments in use.
 569          */
 570         if ((cpu_architecture() >= CPU_ARCH_ARMv6 || cpu_is_xsc3())
 571                 && domain == 0) {
 572                 /*
 573                  * Align to supersection boundary if !high pages.
 574                  * High pages have already been checked for proper
 575                  * alignment above and they will fail the SUPSERSECTION_MASK
 576                  * check because of the way the address is encoded into
 577                  * offset.
 578                  */
 579                 if (md->pfn <= 0x100000) {
 580                         while ((virt & ~SUPERSECTION_MASK ||
 581                                 (virt + off) & ~SUPERSECTION_MASK) &&
 582                                 length >= (PGDIR_SIZE / 2)) {
 583                                 alloc_init_section(virt, virt + off, prot_sect);
 584
 585                                 virt   += (PGDIR_SIZE / 2);
 586                                 length -= (PGDIR_SIZE / 2);
 587                         }
 588                 }
 589
 590                 while (length >= SUPERSECTION_SIZE) {
 591                         alloc_init_supersection(virt, virt + off, prot_sect);
 592
 593                         virt   += SUPERSECTION_SIZE;
 594                         length -= SUPERSECTION_SIZE;
 595                 }
 596         }
 597
 598         /*
 599          * A section mapping covers half a "pgdir" entry.
 600          */
 601         while (length >= (PGDIR_SIZE / 2)) {
 602                 alloc_init_section(virt, virt + off, prot_sect);
 603
 604                 virt   += (PGDIR_SIZE / 2);
 605                 length -= (PGDIR_SIZE / 2);
 606         }
 607
 608         while (length >= PAGE_SIZE) {
 609                 alloc_init_page(virt, virt + off, prot_l1, prot_pte);
 610
 611                 virt   += PAGE_SIZE;
 612                 length -= PAGE_SIZE;
 613         }
 614 }
 615
 616 /*
 617  * In order to soft-boot, we need to insert a 1:1 mapping in place of
 618  * the user-mode pages.  This will then ensure that we have predictable
 619  * results when turning the mmu off
 620  */
 621 void setup_mm_for_reboot(char mode)
 622 {
 623         unsigned long base_pmdval;
 624         pgd_t *pgd;
 625         int i;
 626
 627         if (current->mm && current->mm->pgd)
 628                 pgd = current->mm->pgd;
 629         else
 630                 pgd = init_mm.pgd;
 631
 632         base_pmdval = PMD_SECT_AP_WRITE | PMD_SECT_AP_READ | PMD_TYPE_SECT;
 633         if (cpu_architecture() <= CPU_ARCH_ARMv5TEJ && !cpu_is_xscale())
 634                 base_pmdval |= PMD_BIT4;
 635
 636         for (i = 0; i < FIRST_USER_PGD_NR + USER_PTRS_PER_PGD; i++, pgd++) {
 637                 unsigned long pmdval = (i << PGDIR_SHIFT) | base_pmdval;
 638                 pmd_t *pmd;
 639
 640                 pmd = pmd_off(pgd, i << PGDIR_SHIFT);
 641                 pmd[0] = __pmd(pmdval);
 642                 pmd[1] = __pmd(pmdval + (1 << (PGDIR_SHIFT - 1)));
 643                 flush_pmd_entry(pmd);
 644         }
 645 }
 646
 647 /*
 648  * Create the architecture specific mappings
 649  */
 650 void __init iotable_init(struct map_desc *io_desc, int nr)
 651 {
 652         int i;
 653
 654         for (i = 0; i < nr; i++)
 655                 create_mapping(io_desc + i);
 656 }