arch/ppc/mm/init.c

   1 /*
   2  *  PowerPC version
   3  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   4  *
   5  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
   6  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
   7  *    Copyright (C) 1996 Paul Mackerras
   8  *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
   9  *  PPC44x/36-bit changes by Matt Porter (mporter@mvista.com)
  10  *
  11  *  Derived from "arch/i386/mm/init.c"
  12  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  13  *
  14  *  This program is free software; you can redistribute it and/or
  15  *  modify it under the terms of the GNU General Public License
  16  *  as published by the Free Software Foundation; either version
  17  *  2 of the License, or (at your option) any later version.
  18  *
  19  */
  20
  21 #include <linux/config.h>
  22 #include <linux/module.h>
  23 #include <linux/sched.h>
  24 #include <linux/kernel.h>
  25 #include <linux/errno.h>
  26 #include <linux/string.h>
  27 #include <linux/types.h>
  28 #include <linux/mm.h>
  29 #include <linux/stddef.h>
  30 #include <linux/init.h>
  31 #include <linux/bootmem.h>
  32 #include <linux/highmem.h>
  33 #include <linux/initrd.h>
  34 #include <linux/pagemap.h>
  35
  36 #include <asm/pgalloc.h>
  37 #include <asm/prom.h>
  38 #include <asm/io.h>
  39 #include <asm/mmu_context.h>
  40 #include <asm/pgtable.h>
  41 #include <asm/mmu.h>
  42 #include <asm/smp.h>
  43 #include <asm/machdep.h>
  44 #include <asm/btext.h>
  45 #include <asm/tlb.h>
  46 #include <asm/bootinfo.h>
  47
  48 #include "mem_pieces.h"
  49 #include "mmu_decl.h"
  50
  51 #if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
  52 /* The ammount of lowmem must be within 0xF0000000 - KERNELBASE. */
  53 #if (CONFIG_LOWMEM_SIZE > (0xF0000000 - KERNELBASE))
  54 #error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_START_KERNEL"
  55 #endif
  56 #endif
  57 #define MAX_LOW_MEM     CONFIG_LOWMEM_SIZE
  58
  59 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  60
  61 unsigned long total_memory;
  62 unsigned long total_lowmem;
  63
  64 unsigned long ppc_memstart;
  65 unsigned long ppc_memoffset = PAGE_OFFSET;
  66
  67 int mem_init_done;
  68 int init_bootmem_done;
  69 int boot_mapsize;
  70 #ifdef CONFIG_PPC_PMAC
  71 unsigned long agp_special_page;
  72 #endif
  73
  74 extern char _end[];
  75 extern char etext[], _stext[];
  76 extern char __init_begin, __init_end;
  77 extern char __prep_begin, __prep_end;
  78 extern char __chrp_begin, __chrp_end;
  79 extern char __pmac_begin, __pmac_end;
  80 extern char __openfirmware_begin, __openfirmware_end;
  81
  82 #ifdef CONFIG_HIGHMEM
  83 pte_t *kmap_pte;
  84 pgprot_t kmap_prot;
  85
  86 EXPORT_SYMBOL(kmap_prot);
  87 EXPORT_SYMBOL(kmap_pte);
  88 #endif
  89
  90 void MMU_init(void);
  91 void set_phys_avail(unsigned long total_ram);
  92
  93 /* XXX should be in current.h  -- paulus */
  94 extern struct task_struct *current_set[NR_CPUS];
  95
  96 char *klimit = _end;
  97 struct mem_pieces phys_avail;
  98
  99 extern char *sysmap;
 100 extern unsigned long sysmap_size;
 101
 102 /*
 103  * this tells the system to map all of ram with the segregs
 104  * (i.e. page tables) instead of the bats.
 105  * -- Cort
 106  */
 107 int __map_without_bats;
 108 int __map_without_ltlbs;
 109
 110 /* max amount of RAM to use */
 111 unsigned long __max_memory;
 112 /* max amount of low RAM to map in */
 113 unsigned long __max_low_memory = MAX_LOW_MEM;
 114
 115 void show_mem(void)
 116 {
 117         int i,free = 0,total = 0,reserved = 0;
 118         int shared = 0, cached = 0;
 119         int highmem = 0;
 120
 121         printk("Mem-info:\n");
 122         show_free_areas();
 123         printk("Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
 124         i = max_mapnr;
 125         while (i-- > 0) {
 126                 total++;
 127                 if (PageHighMem(mem_map+i))
 128                         highmem++;
 129                 if (PageReserved(mem_map+i))
 130                         reserved++;
 131                 else if (PageSwapCache(mem_map+i))
 132                         cached++;
 133                 else if (!page_count(mem_map+i))
 134                         free++;
 135                 else
 136                         shared += page_count(mem_map+i) - 1;
 137         }
 138         printk("%d pages of RAM\n",total);
 139         printk("%d pages of HIGHMEM\n", highmem);
 140         printk("%d free pages\n",free);
 141         printk("%d reserved pages\n",reserved);
 142         printk("%d pages shared\n",shared);
 143         printk("%d pages swap cached\n",cached);
 144 }
 145
 146 /* Free up now-unused memory */
 147 static void free_sec(unsigned long start, unsigned long end, const char *name)
 148 {
 149         unsigned long cnt = 0;
 150
 151         while (start < end) {
 152                 ClearPageReserved(virt_to_page(start));
 153                 set_page_count(virt_to_page(start), 1);
 154                 free_page(start);
 155                 cnt++;
 156                 start += PAGE_SIZE;
 157         }
 158         if (cnt) {
 159                 printk(" %ldk %s", cnt << (PAGE_SHIFT - 10), name);
 160                 totalram_pages += cnt;
 161         }
 162 }
 163
 164 void free_initmem(void)
 165 {
 166 #define FREESEC(TYPE) \
 167         free_sec((unsigned long)(&__ ## TYPE ## _begin), \
 168                  (unsigned long)(&__ ## TYPE ## _end), \
 169                  #TYPE);
 170
 171         printk ("Freeing unused kernel memory:");
 172         FREESEC(init);
 173         if (_machine != _MACH_Pmac)
 174                 FREESEC(pmac);
 175         if (_machine != _MACH_chrp)
 176                 FREESEC(chrp);
 177         if (_machine != _MACH_prep)
 178                 FREESEC(prep);
 179         if (!have_of)
 180                 FREESEC(openfirmware);
 181         printk("\n");
 182 #undef FREESEC
 183 }
 184
 185 #ifdef CONFIG_BLK_DEV_INITRD
 186 void free_initrd_mem(unsigned long start, unsigned long end)
 187 {
 188         printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
 189
 190         for (; start < end; start += PAGE_SIZE) {
 191                 ClearPageReserved(virt_to_page(start));
 192                 set_page_count(virt_to_page(start), 1);
 193                 free_page(start);
 194                 totalram_pages++;
 195         }
 196 }
 197 #endif
 198
 199 /*
 200  * Check for command-line options that affect what MMU_init will do.
 201  */
 202 void MMU_setup(void)
 203 {
 204         /* Check for nobats option (used in mapin_ram). */
 205         if (strstr(cmd_line, "nobats")) {
 206                 __map_without_bats = 1;
 207         }
 208
 209         if (strstr(cmd_line, "noltlbs")) {
 210                 __map_without_ltlbs = 1;
 211         }
 212
 213         /* Look for mem= option on command line */
 214         if (strstr(cmd_line, "mem=")) {
 215                 char *p, *q;
 216                 unsigned long maxmem = 0;
 217
 218                 for (q = cmd_line; (p = strstr(q, "mem=")) != 0; ) {
 219                         q = p + 4;
 220                         if (p > cmd_line && p[-1] != ' ')
 221                                 continue;
 222                         maxmem = simple_strtoul(q, &q, 0);
 223                         if (*q == 'k' || *q == 'K') {
 224                                 maxmem <<= 10;
 225                                 ++q;
 226                         } else if (*q == 'm' || *q == 'M') {
 227                                 maxmem <<= 20;
 228                                 ++q;
 229                         }
 230                 }
 231                 __max_memory = maxmem;
 232         }
 233 }
 234
 235 /*
 236  * MMU_init sets up the basic memory mappings for the kernel,
 237  * including both RAM and possibly some I/O regions,
 238  * and sets up the page tables and the MMU hardware ready to go.
 239  */
 240 void __init MMU_init(void)
 241 {
 242         if (ppc_md.progress)
 243                 ppc_md.progress("MMU:enter", 0x111);
 244
 245         /* parse args from command line */
 246         MMU_setup();
 247
 248         /*
 249          * Figure out how much memory we have, how much
 250          * is lowmem, and how much is highmem.  If we were
 251          * passed the total memory size from the bootloader,
 252          * just use it.
 253          */
 254         if (boot_mem_size)
 255                 total_memory = boot_mem_size;
 256         else
 257                 total_memory = ppc_md.find_end_of_memory();
 258
 259         if (__max_memory && total_memory > __max_memory)
 260                 total_memory = __max_memory;
 261         total_lowmem = total_memory;
 262 #ifdef CONFIG_FSL_BOOKE
 263         /* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
 264          * entries, so we need to adjust lowmem to match the amount we can map
 265          * in the fixed entries */
 266         adjust_total_lowmem();
 267 #endif /* CONFIG_FSL_BOOKE */
 268         if (total_lowmem > __max_low_memory) {
 269                 total_lowmem = __max_low_memory;
 270 #ifndef CONFIG_HIGHMEM
 271                 total_memory = total_lowmem;
 272 #endif /* CONFIG_HIGHMEM */
 273         }
 274         set_phys_avail(total_lowmem);
 275
 276         /* Initialize the MMU hardware */
 277         if (ppc_md.progress)
 278                 ppc_md.progress("MMU:hw init", 0x300);
 279         MMU_init_hw();
 280
 281         /* Map in all of RAM starting at KERNELBASE */
 282         if (ppc_md.progress)
 283                 ppc_md.progress("MMU:mapin", 0x301);
 284         mapin_ram();
 285
 286 #ifdef CONFIG_HIGHMEM
 287         ioremap_base = PKMAP_BASE;
 288 #else
 289         ioremap_base = 0xfe000000UL;    /* for now, could be 0xfffff000 */
 290 #endif /* CONFIG_HIGHMEM */
 291         ioremap_bot = ioremap_base;
 292
 293         /* Map in I/O resources */
 294         if (ppc_md.progress)
 295                 ppc_md.progress("MMU:setio", 0x302);
 296         if (ppc_md.setup_io_mappings)
 297                 ppc_md.setup_io_mappings();
 298
 299         /* Initialize the context management stuff */
 300         mmu_context_init();
 301
 302         if (ppc_md.progress)
 303                 ppc_md.progress("MMU:exit", 0x211);
 304
 305 #ifdef CONFIG_BOOTX_TEXT
 306         /* By default, we are no longer mapped */
 307         boot_text_mapped = 0;
 308         /* Must be done last, or ppc_md.progress will die. */
 309         map_boot_text();
 310 #endif
 311 }
 312
 313 /* This is only called until mem_init is done. */
 314 void __init *early_get_page(void)
 315 {
 316         void *p;
 317
 318         if (init_bootmem_done) {
 319                 p = alloc_bootmem_pages(PAGE_SIZE);
 320         } else {
 321                 p = mem_pieces_find(PAGE_SIZE, PAGE_SIZE);
 322         }
 323         return p;
 324 }
 325
 326 /*
 327  * Initialize the bootmem system and give it all the memory we
 328  * have available.
 329  */
 330 void __init do_init_bootmem(void)
 331 {
 332         unsigned long start, size;
 333         int i;
 334
 335         /*
 336          * Find an area to use for the bootmem bitmap.
 337          * We look for the first area which is at least
 338          * 128kB in length (128kB is enough for a bitmap
 339          * for 4GB of memory, using 4kB pages), plus 1 page
 340          * (in case the address isn't page-aligned).
 341          */
 342         start = 0;
 343         size = 0;
 344         for (i = 0; i < phys_avail.n_regions; ++i) {
 345                 unsigned long a = phys_avail.regions[i].address;
 346                 unsigned long s = phys_avail.regions[i].size;
 347                 if (s <= size)
 348                         continue;
 349                 start = a;
 350                 size = s;
 351                 if (s >= 33 * PAGE_SIZE)
 352                         break;
 353         }
 354         start = PAGE_ALIGN(start);
 355
 356         min_low_pfn = start >> PAGE_SHIFT;
 357         max_low_pfn = (PPC_MEMSTART + total_lowmem) >> PAGE_SHIFT;
 358         max_pfn = (PPC_MEMSTART + total_memory) >> PAGE_SHIFT;
 359         boot_mapsize = init_bootmem_node(&contig_page_data, min_low_pfn,
 360                                          PPC_MEMSTART >> PAGE_SHIFT,
 361                                          max_low_pfn);
 362
 363         /* remove the bootmem bitmap from the available memory */
 364         mem_pieces_remove(&phys_avail, start, boot_mapsize, 1);
 365
 366         /* add everything in phys_avail into the bootmem map */
 367         for (i = 0; i < phys_avail.n_regions; ++i)
 368                 free_bootmem(phys_avail.regions[i].address,
 369                              phys_avail.regions[i].size);
 370
 371         init_bootmem_done = 1;
 372 }
 373
 374 /*
 375  * paging_init() sets up the page tables - in fact we've already done this.
 376  */
 377 void __init paging_init(void)
 378 {
 379         unsigned long zones_size[MAX_NR_ZONES], i;
 380
 381 #ifdef CONFIG_HIGHMEM
 382         map_page(PKMAP_BASE, 0, 0);     /* XXX gross */
 383         pkmap_page_table = pte_offset_kernel(pmd_offset(pgd_offset_k
 384                         (PKMAP_BASE), PKMAP_BASE), PKMAP_BASE);
 385         map_page(KMAP_FIX_BEGIN, 0, 0); /* XXX gross */
 386         kmap_pte = pte_offset_kernel(pmd_offset(pgd_offset_k
 387                         (KMAP_FIX_BEGIN), KMAP_FIX_BEGIN), KMAP_FIX_BEGIN);
 388         kmap_prot = PAGE_KERNEL;
 389 #endif /* CONFIG_HIGHMEM */
 390
 391         /*
 392          * All pages are DMA-able so we put them all in the DMA zone.
 393          */
 394         zones_size[ZONE_DMA] = total_lowmem >> PAGE_SHIFT;
 395         for (i = 1; i < MAX_NR_ZONES; i++)
 396                 zones_size[i] = 0;
 397
 398 #ifdef CONFIG_HIGHMEM
 399         zones_size[ZONE_HIGHMEM] = (total_memory - total_lowmem) >> PAGE_SHIFT;
 400 #endif /* CONFIG_HIGHMEM */
 401
 402         free_area_init(zones_size);
 403 }
 404
 405 void __init mem_init(void)
 406 {
 407         unsigned long addr;
 408         int codepages = 0;
 409         int datapages = 0;
 410         int initpages = 0;
 411 #ifdef CONFIG_HIGHMEM
 412         unsigned long highmem_mapnr;
 413
 414         highmem_mapnr = total_lowmem >> PAGE_SHIFT;
 415 #endif /* CONFIG_HIGHMEM */
 416         max_mapnr = total_memory >> PAGE_SHIFT;
 417
 418         high_memory = (void *) __va(PPC_MEMSTART + total_lowmem);
 419         num_physpages = max_mapnr;      /* RAM is assumed contiguous */
 420
 421         totalram_pages += free_all_bootmem();
 422
 423 #ifdef CONFIG_BLK_DEV_INITRD
 424         /* if we are booted from BootX with an initial ramdisk,
 425            make sure the ramdisk pages aren't reserved. */
 426         if (initrd_start) {
 427                 for (addr = initrd_start; addr < initrd_end; addr += PAGE_SIZE)
 428                         ClearPageReserved(virt_to_page(addr));
 429         }
 430 #endif /* CONFIG_BLK_DEV_INITRD */
 431
 432 #ifdef CONFIG_PPC_OF
 433         /* mark the RTAS pages as reserved */
 434         if ( rtas_data )
 435                 for (addr = (ulong)__va(rtas_data);
 436                      addr < PAGE_ALIGN((ulong)__va(rtas_data)+rtas_size) ;
 437                      addr += PAGE_SIZE)
 438                         SetPageReserved(virt_to_page(addr));
 439 #endif
 440 #ifdef CONFIG_PPC_PMAC
 441         if (agp_special_page)
 442                 SetPageReserved(virt_to_page(agp_special_page));
 443 #endif
 444         if ( sysmap )
 445                 for (addr = (unsigned long)sysmap;
 446                      addr < PAGE_ALIGN((unsigned long)sysmap+sysmap_size) ;
 447                      addr += PAGE_SIZE)
 448                         SetPageReserved(virt_to_page(addr));
 449
 450         for (addr = PAGE_OFFSET; addr < (unsigned long)high_memory;
 451              addr += PAGE_SIZE) {
 452                 if (!PageReserved(virt_to_page(addr)))
 453                         continue;
 454                 if (addr < (ulong) etext)
 455                         codepages++;
 456                 else if (addr >= (unsigned long)&__init_begin
 457                          && addr < (unsigned long)&__init_end)
 458                         initpages++;
 459                 else if (addr < (ulong) klimit)
 460                         datapages++;
 461         }
 462
 463 #ifdef CONFIG_HIGHMEM
 464         {
 465                 unsigned long pfn;
 466
 467                 for (pfn = highmem_mapnr; pfn < max_mapnr; ++pfn) {
 468                         struct page *page = mem_map + pfn;
 469
 470                         ClearPageReserved(page);
 471                         set_bit(PG_highmem, &page->flags);
 472                         set_page_count(page, 1);
 473                         __free_page(page);
 474                         totalhigh_pages++;
 475                 }
 476                 totalram_pages += totalhigh_pages;
 477         }
 478 #endif /* CONFIG_HIGHMEM */
 479
 480         printk("Memory: %luk available (%dk kernel code, %dk data, %dk init, %ldk highmem)\n",
 481                (unsigned long)nr_free_pages()<< (PAGE_SHIFT-10),
 482                codepages<< (PAGE_SHIFT-10), datapages<< (PAGE_SHIFT-10),
 483                initpages<< (PAGE_SHIFT-10),
 484                (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)));
 485         if (sysmap)
 486                 printk("System.map loaded at 0x%08x for debugger, size: %ld bytes\n",
 487                         (unsigned int)sysmap, sysmap_size);
 488 #ifdef CONFIG_PPC_PMAC
 489         if (agp_special_page)
 490                 printk(KERN_INFO "AGP special page: 0x%08lx\n", agp_special_page);
 491 #endif
 492
 493         mem_init_done = 1;
 494 }
 495
 496 /*
 497  * Set phys_avail to the amount of physical memory,
 498  * less the kernel text/data/bss.
 499  */
 500 void __init
 501 set_phys_avail(unsigned long total_memory)
 502 {
 503         unsigned long kstart, ksize;
 504
 505         /*
 506          * Initially, available physical memory is equivalent to all
 507          * physical memory.
 508          */
 509
 510         phys_avail.regions[0].address = PPC_MEMSTART;
 511         phys_avail.regions[0].size = total_memory;
 512         phys_avail.n_regions = 1;
 513
 514         /*
 515          * Map out the kernel text/data/bss from the available physical
 516          * memory.
 517          */
 518
 519         kstart = __pa(_stext);  /* should be 0 */
 520         ksize = PAGE_ALIGN(klimit - _stext);
 521
 522         mem_pieces_remove(&phys_avail, kstart, ksize, 0);
 523         mem_pieces_remove(&phys_avail, 0, 0x4000, 0);
 524
 525 #if defined(CONFIG_BLK_DEV_INITRD)
 526         /* Remove the init RAM disk from the available memory. */
 527         if (initrd_start) {
 528                 mem_pieces_remove(&phys_avail, __pa(initrd_start),
 529                                   initrd_end - initrd_start, 1);
 530         }
 531 #endif /* CONFIG_BLK_DEV_INITRD */
 532 #ifdef CONFIG_PPC_OF
 533         /* remove the RTAS pages from the available memory */
 534         if (rtas_data)
 535                 mem_pieces_remove(&phys_avail, rtas_data, rtas_size, 1);
 536 #endif
 537         /* remove the sysmap pages from the available memory */
 538         if (sysmap)
 539                 mem_pieces_remove(&phys_avail, __pa(sysmap), sysmap_size, 1);
 540 #ifdef CONFIG_PPC_PMAC
 541         /* Because of some uninorth weirdness, we need a page of
 542          * memory as high as possible (it must be outside of the
 543          * bus address seen as the AGP aperture). It will be used
 544          * by the r128 DRM driver
 545          *
 546          * FIXME: We need to make sure that page doesn't overlap any of the\
 547          * above. This could be done by improving mem_pieces_find to be able
 548          * to do a backward search from the end of the list.
 549          */
 550         if (_machine == _MACH_Pmac && find_devices("uni-north-agp")) {
 551                 agp_special_page = (total_memory - PAGE_SIZE);
 552                 mem_pieces_remove(&phys_avail, agp_special_page, PAGE_SIZE, 0);
 553                 agp_special_page = (unsigned long)__va(agp_special_page);
 554         }
 555 #endif /* CONFIG_PPC_PMAC */
 556 }
 557
 558 /* Mark some memory as reserved by removing it from phys_avail. */
 559 void __init reserve_phys_mem(unsigned long start, unsigned long size)
 560 {
 561         mem_pieces_remove(&phys_avail, start, size, 1);
 562 }
 563
 564 /*
 565  * This is called when a page has been modified by the kernel.
 566  * It just marks the page as not i-cache clean.  We do the i-cache
 567  * flush later when the page is given to a user process, if necessary.
 568  */
 569 void flush_dcache_page(struct page *page)
 570 {
 571         clear_bit(PG_arch_1, &page->flags);
 572 }
 573
 574 void flush_dcache_icache_page(struct page *page)
 575 {
 576 #ifdef CONFIG_BOOKE
 577         __flush_dcache_icache(kmap(page));
 578         kunmap(page);
 579 #else
 580         __flush_dcache_icache_phys(page_to_pfn(page) << PAGE_SHIFT);
 581 #endif
 582
 583 }
 584 void clear_user_page(void *page, unsigned long vaddr, struct page *pg)
 585 {
 586         clear_page(page);
 587         clear_bit(PG_arch_1, &pg->flags);
 588 }
 589
 590 void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
 591                     struct page *pg)
 592 {
 593         copy_page(vto, vfrom);
 594         clear_bit(PG_arch_1, &pg->flags);
 595 }
 596
 597 void flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
 598                              unsigned long addr, int len)
 599 {
 600         unsigned long maddr;
 601
 602         maddr = (unsigned long) kmap(page) + (addr & ~PAGE_MASK);
 603         flush_icache_range(maddr, maddr + len);
 604         kunmap(page);
 605 }
 606
 607 /*
 608  * This is called at the end of handling a user page fault, when the
 609  * fault has been handled by updating a PTE in the linux page tables.
 610  * We use it to preload an HPTE into the hash table corresponding to
 611  * the updated linux PTE.
 612  */
 613 void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
 614                       pte_t pte)
 615 {
 616         /* handle i-cache coherency */
 617         unsigned long pfn = pte_pfn(pte);
 618
 619         if (pfn_valid(pfn)) {
 620                 struct page *page = pfn_to_page(pfn);
 621                 if (!PageReserved(page)
 622                     && !test_bit(PG_arch_1, &page->flags)) {
 623                         if (vma->vm_mm == current->active_mm)
 624                                 __flush_dcache_icache((void *) address);
 625                         else
 626                                 flush_dcache_icache_page(page);
 627                         set_bit(PG_arch_1, &page->flags);
 628                 }
 629         }
 630
 631 #ifdef CONFIG_PPC_STD_MMU
 632         /* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */
 633         if (Hash != 0 && pte_young(pte)) {
 634                 struct mm_struct *mm;
 635                 pmd_t *pmd;
 636
 637                 mm = (address < TASK_SIZE)? vma->vm_mm: &init_mm;
 638                 pmd = pmd_offset(pgd_offset(mm, address), address);
 639                 if (!pmd_none(*pmd))
 640                         add_hash_page(mm->context, address, pmd_val(*pmd));
 641         }
 642 #endif
 643 }
 644
 645 /*
 646  * This is called by /dev/mem to know if a given address has to
 647  * be mapped non-cacheable or not
 648  */
 649 int page_is_ram(unsigned long pfn)
 650 {
 651         unsigned long paddr = (pfn << PAGE_SHIFT);
 652
 653         return paddr < __pa(high_memory);
 654 }
 655
 656 pgprot_t phys_mem_access_prot(struct file *file, unsigned long addr,
 657                               unsigned long size, pgprot_t vma_prot)
 658 {
 659         if (ppc_md.phys_mem_access_prot)
 660                 return ppc_md.phys_mem_access_prot(file, addr, size, vma_prot);
 661
 662         if (!page_is_ram(addr >> PAGE_SHIFT))
 663                 vma_prot = __pgprot(pgprot_val(vma_prot)
 664                                     | _PAGE_GUARDED | _PAGE_NO_CACHE);
 665         return vma_prot;
 666 }
 667 EXPORT_SYMBOL(phys_mem_access_prot);