arch/x86/mm/init.c

   1 #include <linux/initrd.h>
   2 #include <linux/ioport.h>
   3 #include <linux/swap.h>
   4
   5 #include <asm/cacheflush.h>
   6 #include <asm/e820.h>
   7 #include <asm/init.h>
   8 #include <asm/page.h>
   9 #include <asm/page_types.h>
  10 #include <asm/sections.h>
  11 #include <asm/setup.h>
  12 #include <asm/system.h>
  13 #include <asm/tlbflush.h>
  14 #include <asm/tlb.h>
  15
  16 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  17
  18 unsigned long __initdata e820_table_start;
  19 unsigned long __meminitdata e820_table_end;
  20 unsigned long __meminitdata e820_table_top;
  21
  22 int after_bootmem;
  23
  24 int direct_gbpages
  25 #ifdef CONFIG_DIRECT_GBPAGES
  26                                 = 1
  27 #endif
  28 ;
  29
  30 int nx_enabled;
  31
  32 #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
  33 static int disable_nx __cpuinitdata;
  34
  35 /*
  36  * noexec = on|off
  37  *
  38  * Control non-executable mappings for processes.
  39  *
  40  * on      Enable
  41  * off     Disable
  42  */
  43 static int __init noexec_setup(char *str)
  44 {
  45         if (!str)
  46                 return -EINVAL;
  47         if (!strncmp(str, "on", 2)) {
  48                 __supported_pte_mask |= _PAGE_NX;
  49                 disable_nx = 0;
  50         } else if (!strncmp(str, "off", 3)) {
  51                 disable_nx = 1;
  52                 __supported_pte_mask &= ~_PAGE_NX;
  53         }
  54         return 0;
  55 }
  56 early_param("noexec", noexec_setup);
  57 #endif
  58
  59 #ifdef CONFIG_X86_PAE
  60 static void __init set_nx(void)
  61 {
  62         unsigned int v[4], l, h;
  63
  64         if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {
  65                 cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);
  66
  67                 if ((v[3] & (1 << 20)) && !disable_nx) {
  68                         rdmsr(MSR_EFER, l, h);
  69                         l |= EFER_NX;
  70                         wrmsr(MSR_EFER, l, h);
  71                         nx_enabled = 1;
  72                         __supported_pte_mask |= _PAGE_NX;
  73                 }
  74         }
  75 }
  76 #else
  77 static inline void set_nx(void)
  78 {
  79 }
  80 #endif
  81
  82 #ifdef CONFIG_X86_64
  83 void __cpuinit check_efer(void)
  84 {
  85         unsigned long efer;
  86
  87         rdmsrl(MSR_EFER, efer);
  88         if (!(efer & EFER_NX) || disable_nx)
  89                 __supported_pte_mask &= ~_PAGE_NX;
  90 }
  91 #endif
  92
  93 static void __init find_early_table_space(unsigned long end, int use_pse,
  94                                           int use_gbpages)
  95 {
  96         unsigned long puds, pmds, ptes, tables, start;
  97
  98         puds = (end + PUD_SIZE - 1) >> PUD_SHIFT;
  99         tables = roundup(puds * sizeof(pud_t), PAGE_SIZE);
 100
 101         if (use_gbpages) {
 102                 unsigned long extra;
 103
 104                 extra = end - ((end>>PUD_SHIFT) << PUD_SHIFT);
 105                 pmds = (extra + PMD_SIZE - 1) >> PMD_SHIFT;
 106         } else
 107                 pmds = (end + PMD_SIZE - 1) >> PMD_SHIFT;
 108
 109         tables += roundup(pmds * sizeof(pmd_t), PAGE_SIZE);
 110
 111         if (use_pse) {
 112                 unsigned long extra;
 113
 114                 extra = end - ((end>>PMD_SHIFT) << PMD_SHIFT);
 115 #ifdef CONFIG_X86_32
 116                 extra += PMD_SIZE;
 117 #endif
 118                 ptes = (extra + PAGE_SIZE - 1) >> PAGE_SHIFT;
 119         } else
 120                 ptes = (end + PAGE_SIZE - 1) >> PAGE_SHIFT;
 121
 122         tables += roundup(ptes * sizeof(pte_t), PAGE_SIZE);
 123
 124 #ifdef CONFIG_X86_32
 125         /* for fixmap */
 126         tables += roundup(__end_of_fixed_addresses * sizeof(pte_t), PAGE_SIZE);
 127 #endif
 128
 129         /*
 130          * RED-PEN putting page tables only on node 0 could
 131          * cause a hotspot and fill up ZONE_DMA. The page tables
 132          * need roughly 0.5KB per GB.
 133          */
 134 #ifdef CONFIG_X86_32
 135         start = 0x7000;
 136 #else
 137         start = 0x8000;
 138 #endif
 139         e820_table_start = find_e820_area(start, max_pfn_mapped<<PAGE_SHIFT,
 140                                         tables, PAGE_SIZE);
 141         if (e820_table_start == -1UL)
 142                 panic("Cannot find space for the kernel page tables");
 143
 144         e820_table_start >>= PAGE_SHIFT;
 145         e820_table_end = e820_table_start;
 146         e820_table_top = e820_table_start + (tables >> PAGE_SHIFT);
 147
 148         printk(KERN_DEBUG "kernel direct mapping tables up to %lx @ %lx-%lx\n",
 149                 end, e820_table_start << PAGE_SHIFT, e820_table_top << PAGE_SHIFT);
 150 }
 151
 152 struct map_range {
 153         unsigned long start;
 154         unsigned long end;
 155         unsigned page_size_mask;
 156 };
 157
 158 #ifdef CONFIG_X86_32
 159 #define NR_RANGE_MR 3
 160 #else /* CONFIG_X86_64 */
 161 #define NR_RANGE_MR 5
 162 #endif
 163
 164 static int __meminit save_mr(struct map_range *mr, int nr_range,
 165                              unsigned long start_pfn, unsigned long end_pfn,
 166                              unsigned long page_size_mask)
 167 {
 168         if (start_pfn < end_pfn) {
 169                 if (nr_range >= NR_RANGE_MR)
 170                         panic("run out of range for init_memory_mapping\n");
 171                 mr[nr_range].start = start_pfn<<PAGE_SHIFT;
 172                 mr[nr_range].end   = end_pfn<<PAGE_SHIFT;
 173                 mr[nr_range].page_size_mask = page_size_mask;
 174                 nr_range++;
 175         }
 176
 177         return nr_range;
 178 }
 179
 180 #ifdef CONFIG_X86_64
 181 static void __init init_gbpages(void)
 182 {
 183         if (direct_gbpages && cpu_has_gbpages)
 184                 printk(KERN_INFO "Using GB pages for direct mapping\n");
 185         else
 186                 direct_gbpages = 0;
 187 }
 188 #else
 189 static inline void init_gbpages(void)
 190 {
 191 }
 192 #endif
 193
 194 /*
 195  * Setup the direct mapping of the physical memory at PAGE_OFFSET.
 196  * This runs before bootmem is initialized and gets pages directly from
 197  * the physical memory. To access them they are temporarily mapped.
 198  */
 199 unsigned long __init_refok init_memory_mapping(unsigned long start,
 200                                                unsigned long end)
 201 {
 202         unsigned long page_size_mask = 0;
 203         unsigned long start_pfn, end_pfn;
 204         unsigned long ret = 0;
 205         unsigned long pos;
 206
 207         struct map_range mr[NR_RANGE_MR];
 208         int nr_range, i;
 209         int use_pse, use_gbpages;
 210
 211         printk(KERN_INFO "init_memory_mapping: %016lx-%016lx\n", start, end);
 212
 213         if (!after_bootmem)
 214                 init_gbpages();
 215
 216 #ifdef CONFIG_DEBUG_PAGEALLOC
 217         /*
 218          * For CONFIG_DEBUG_PAGEALLOC, identity mapping will use small pages.
 219          * This will simplify cpa(), which otherwise needs to support splitting
 220          * large pages into small in interrupt context, etc.
 221          */
 222         use_pse = use_gbpages = 0;
 223 #else
 224         use_pse = cpu_has_pse;
 225         use_gbpages = direct_gbpages;
 226 #endif
 227
 228         set_nx();
 229         if (nx_enabled)
 230                 printk(KERN_INFO "NX (Execute Disable) protection: active\n");
 231
 232         /* Enable PSE if available */
 233         if (cpu_has_pse)
 234                 set_in_cr4(X86_CR4_PSE);
 235
 236         /* Enable PGE if available */
 237         if (cpu_has_pge) {
 238                 set_in_cr4(X86_CR4_PGE);
 239                 __supported_pte_mask |= _PAGE_GLOBAL;
 240         }
 241
 242         if (use_gbpages)
 243                 page_size_mask |= 1 << PG_LEVEL_1G;
 244         if (use_pse)
 245                 page_size_mask |= 1 << PG_LEVEL_2M;
 246
 247         memset(mr, 0, sizeof(mr));
 248         nr_range = 0;
 249
 250         /* head if not big page alignment ? */
 251         start_pfn = start >> PAGE_SHIFT;
 252         pos = start_pfn << PAGE_SHIFT;
 253 #ifdef CONFIG_X86_32
 254         /*
 255          * Don't use a large page for the first 2/4MB of memory
 256          * because there are often fixed size MTRRs in there
 257          * and overlapping MTRRs into large pages can cause
 258          * slowdowns.
 259          */
 260         if (pos == 0)
 261                 end_pfn = 1<<(PMD_SHIFT - PAGE_SHIFT);
 262         else
 263                 end_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
 264                                  << (PMD_SHIFT - PAGE_SHIFT);
 265 #else /* CONFIG_X86_64 */
 266         end_pfn = ((pos + (PMD_SIZE - 1)) >> PMD_SHIFT)
 267                         << (PMD_SHIFT - PAGE_SHIFT);
 268 #endif
 269         if (end_pfn > (end >> PAGE_SHIFT))
 270                 end_pfn = end >> PAGE_SHIFT;
 271         if (start_pfn < end_pfn) {
 272                 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
 273                 pos = end_pfn << PAGE_SHIFT;
 274         }
 275
 276         /* big page (2M) range */
 277         start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
 278                          << (PMD_SHIFT - PAGE_SHIFT);
 279 #ifdef CONFIG_X86_32
 280         end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
 281 #else /* CONFIG_X86_64 */
 282         end_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
 283                          << (PUD_SHIFT - PAGE_SHIFT);
 284         if (end_pfn > ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT)))
 285                 end_pfn = ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT));
 286 #endif
 287
 288         if (start_pfn < end_pfn) {
 289                 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
 290                                 page_size_mask & (1<<PG_LEVEL_2M));
 291                 pos = end_pfn << PAGE_SHIFT;
 292         }
 293
 294 #ifdef CONFIG_X86_64
 295         /* big page (1G) range */
 296         start_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
 297                          << (PUD_SHIFT - PAGE_SHIFT);
 298         end_pfn = (end >> PUD_SHIFT) << (PUD_SHIFT - PAGE_SHIFT);
 299         if (start_pfn < end_pfn) {
 300                 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
 301                                 page_size_mask &
 302                                  ((1<<PG_LEVEL_2M)|(1<<PG_LEVEL_1G)));
 303                 pos = end_pfn << PAGE_SHIFT;
 304         }
 305
 306         /* tail is not big page (1G) alignment */
 307         start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
 308                          << (PMD_SHIFT - PAGE_SHIFT);
 309         end_pfn = (end >> PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
 310         if (start_pfn < end_pfn) {
 311                 nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
 312                                 page_size_mask & (1<<PG_LEVEL_2M));
 313                 pos = end_pfn << PAGE_SHIFT;
 314         }
 315 #endif
 316
 317         /* tail is not big page (2M) alignment */
 318         start_pfn = pos>>PAGE_SHIFT;
 319         end_pfn = end>>PAGE_SHIFT;
 320         nr_range = save_mr(mr, nr_range, start_pfn, end_pfn, 0);
 321
 322         /* try to merge same page size and continuous */
 323         for (i = 0; nr_range > 1 && i < nr_range - 1; i++) {
 324                 unsigned long old_start;
 325                 if (mr[i].end != mr[i+1].start ||
 326                     mr[i].page_size_mask != mr[i+1].page_size_mask)
 327                         continue;
 328                 /* move it */
 329                 old_start = mr[i].start;
 330                 memmove(&mr[i], &mr[i+1],
 331                         (nr_range - 1 - i) * sizeof(struct map_range));
 332                 mr[i--].start = old_start;
 333                 nr_range--;
 334         }
 335
 336         for (i = 0; i < nr_range; i++)
 337                 printk(KERN_DEBUG " %010lx - %010lx page %s\n",
 338                                 mr[i].start, mr[i].end,
 339                         (mr[i].page_size_mask & (1<<PG_LEVEL_1G))?"1G":(
 340                          (mr[i].page_size_mask & (1<<PG_LEVEL_2M))?"2M":"4k"));
 341
 342         /*
 343          * Find space for the kernel direct mapping tables.
 344          *
 345          * Later we should allocate these tables in the local node of the
 346          * memory mapped. Unfortunately this is done currently before the
 347          * nodes are discovered.
 348          */
 349         if (!after_bootmem)
 350                 find_early_table_space(end, use_pse, use_gbpages);
 351
 352 #ifdef CONFIG_X86_32
 353         for (i = 0; i < nr_range; i++)
 354                 kernel_physical_mapping_init(mr[i].start, mr[i].end,
 355                                              mr[i].page_size_mask);
 356         ret = end;
 357 #else /* CONFIG_X86_64 */
 358         for (i = 0; i < nr_range; i++)
 359                 ret = kernel_physical_mapping_init(mr[i].start, mr[i].end,
 360                                                    mr[i].page_size_mask);
 361 #endif
 362
 363 #ifdef CONFIG_X86_32
 364         early_ioremap_page_table_range_init();
 365
 366         load_cr3(swapper_pg_dir);
 367 #endif
 368
 369 #ifdef CONFIG_X86_64
 370         if (!after_bootmem && !start) {
 371                 pud_t *pud;
 372                 pmd_t *pmd;
 373
 374                 mmu_cr4_features = read_cr4();
 375
 376                 /*
 377                  * _brk_end cannot change anymore, but it and _end may be
 378                  * located on different 2M pages. cleanup_highmap(), however,
 379                  * can only consider _end when it runs, so destroy any
 380                  * mappings beyond _brk_end here.
 381                  */
 382                 pud = pud_offset(pgd_offset_k(_brk_end), _brk_end);
 383                 pmd = pmd_offset(pud, _brk_end - 1);
 384                 while (++pmd <= pmd_offset(pud, (unsigned long)_end - 1))
 385                         pmd_clear(pmd);
 386         }
 387 #endif
 388         __flush_tlb_all();
 389
 390         if (!after_bootmem && e820_table_end > e820_table_start)
 391                 reserve_early(e820_table_start << PAGE_SHIFT,
 392                                  e820_table_end << PAGE_SHIFT, "PGTABLE");
 393
 394         if (!after_bootmem)
 395                 early_memtest(start, end);
 396
 397         return ret >> PAGE_SHIFT;
 398 }
 399
 400
 401 /*
 402  * devmem_is_allowed() checks to see if /dev/mem access to a certain address
 403  * is valid. The argument is a physical page number.
 404  *
 405  *
 406  * On x86, access has to be given to the first megabyte of ram because that area
 407  * contains bios code and data regions used by X and dosemu and similar apps.
 408  * Access has to be given to non-kernel-ram areas as well, these contain the PCI
 409  * mmio resources as well as potential bios/acpi data regions.
 410  */
 411 int devmem_is_allowed(unsigned long pagenr)
 412 {
 413         if (pagenr <= 256)
 414                 return 1;
 415         if (iomem_is_exclusive(pagenr << PAGE_SHIFT))
 416                 return 0;
 417         if (!page_is_ram(pagenr))
 418                 return 1;
 419         return 0;
 420 }
 421
 422 void free_init_pages(char *what, unsigned long begin, unsigned long end)
 423 {
 424         unsigned long addr = begin;
 425
 426         if (addr >= end)
 427                 return;
 428
 429         /*
 430          * If debugging page accesses then do not free this memory but
 431          * mark them not present - any buggy init-section access will
 432          * create a kernel page fault:
 433          */
 434 #ifdef CONFIG_DEBUG_PAGEALLOC
 435         printk(KERN_INFO "debug: unmapping init memory %08lx..%08lx\n",
 436                 begin, PAGE_ALIGN(end));
 437         set_memory_np(begin, (end - begin) >> PAGE_SHIFT);
 438 #else
 439         /*
 440          * We just marked the kernel text read only above, now that
 441          * we are going to free part of that, we need to make that
 442          * writeable first.
 443          */
 444         set_memory_rw(begin, (end - begin) >> PAGE_SHIFT);
 445
 446         printk(KERN_INFO "Freeing %s: %luk freed\n", what, (end - begin) >> 10);
 447
 448         for (; addr < end; addr += PAGE_SIZE) {
 449                 ClearPageReserved(virt_to_page(addr));
 450                 init_page_count(virt_to_page(addr));
 451                 memset((void *)(addr & ~(PAGE_SIZE-1)),
 452                         POISON_FREE_INITMEM, PAGE_SIZE);
 453                 free_page(addr);
 454                 totalram_pages++;
 455         }
 456 #endif
 457 }
 458
 459 void free_initmem(void)
 460 {
 461         free_init_pages("unused kernel memory",
 462                         (unsigned long)(&__init_begin),
 463                         (unsigned long)(&__init_end));
 464 }
 465
 466 #ifdef CONFIG_BLK_DEV_INITRD
 467 void free_initrd_mem(unsigned long start, unsigned long end)
 468 {
 469         free_init_pages("initrd memory", start, end);
 470 }
 471 #endif