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         ppc_md.progress = NULL;
 183 #undef FREESEC
 184 }
 185
 186 #ifdef CONFIG_BLK_DEV_INITRD
 187 void free_initrd_mem(unsigned long start, unsigned long end)
 188 {
 189         printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
 190
 191         for (; start < end; start += PAGE_SIZE) {
 192                 ClearPageReserved(virt_to_page(start));
 193                 set_page_count(virt_to_page(start), 1);
 194                 free_page(start);
 195                 totalram_pages++;
 196         }
 197 }
 198 #endif
 199
 200 /*
 201  * Check for command-line options that affect what MMU_init will do.
 202  */
 203 void MMU_setup(void)
 204 {
 205         /* Check for nobats option (used in mapin_ram). */
 206         if (strstr(cmd_line, "nobats")) {
 207                 __map_without_bats = 1;
 208         }
 209
 210         if (strstr(cmd_line, "noltlbs")) {
 211                 __map_without_ltlbs = 1;
 212         }
 213
 214         /* Look for mem= option on command line */
 215         if (strstr(cmd_line, "mem=")) {
 216                 char *p, *q;
 217                 unsigned long maxmem = 0;
 218
 219                 for (q = cmd_line; (p = strstr(q, "mem=")) != 0; ) {
 220                         q = p + 4;
 221                         if (p > cmd_line && p[-1] != ' ')
 222                                 continue;
 223                         maxmem = simple_strtoul(q, &q, 0);
 224                         if (*q == 'k' || *q == 'K') {
 225                                 maxmem <<= 10;
 226                                 ++q;
 227                         } else if (*q == 'm' || *q == 'M') {
 228                                 maxmem <<= 20;
 229                                 ++q;
 230                         }
 231                 }
 232                 __max_memory = maxmem;
 233         }
 234 }
 235
 236 /*
 237  * MMU_init sets up the basic memory mappings for the kernel,
 238  * including both RAM and possibly some I/O regions,
 239  * and sets up the page tables and the MMU hardware ready to go.
 240  */
 241 void __init MMU_init(void)
 242 {
 243         if (ppc_md.progress)
 244                 ppc_md.progress("MMU:enter", 0x111);
 245
 246         /* parse args from command line */
 247         MMU_setup();
 248
 249         /*
 250          * Figure out how much memory we have, how much
 251          * is lowmem, and how much is highmem.  If we were
 252          * passed the total memory size from the bootloader,
 253          * just use it.
 254          */
 255         if (boot_mem_size)
 256                 total_memory = boot_mem_size;
 257         else
 258                 total_memory = ppc_md.find_end_of_memory();
 259
 260         if (__max_memory && total_memory > __max_memory)
 261                 total_memory = __max_memory;
 262         total_lowmem = total_memory;
 263 #ifdef CONFIG_FSL_BOOKE
 264         /* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
 265          * entries, so we need to adjust lowmem to match the amount we can map
 266          * in the fixed entries */
 267         adjust_total_lowmem();
 268 #endif /* CONFIG_FSL_BOOKE */
 269         if (total_lowmem > __max_low_memory) {
 270                 total_lowmem = __max_low_memory;
 271 #ifndef CONFIG_HIGHMEM
 272                 total_memory = total_lowmem;
 273 #endif /* CONFIG_HIGHMEM */
 274         }
 275         set_phys_avail(total_lowmem);
 276
 277         /* Initialize the MMU hardware */
 278         if (ppc_md.progress)
 279                 ppc_md.progress("MMU:hw init", 0x300);
 280         MMU_init_hw();
 281
 282         /* Map in all of RAM starting at KERNELBASE */
 283         if (ppc_md.progress)
 284                 ppc_md.progress("MMU:mapin", 0x301);
 285         mapin_ram();
 286
 287 #ifdef CONFIG_HIGHMEM
 288         ioremap_base = PKMAP_BASE;
 289 #else
 290         ioremap_base = 0xfe000000UL;    /* for now, could be 0xfffff000 */
 291 #endif /* CONFIG_HIGHMEM */
 292         ioremap_bot = ioremap_base;
 293
 294         /* Map in I/O resources */
 295         if (ppc_md.progress)
 296                 ppc_md.progress("MMU:setio", 0x302);
 297         if (ppc_md.setup_io_mappings)
 298                 ppc_md.setup_io_mappings();
 299
 300         /* Initialize the context management stuff */
 301         mmu_context_init();
 302
 303         if (ppc_md.progress)
 304                 ppc_md.progress("MMU:exit", 0x211);
 305
 306 #ifdef CONFIG_BOOTX_TEXT
 307         /* By default, we are no longer mapped */
 308         boot_text_mapped = 0;
 309         /* Must be done last, or ppc_md.progress will die. */
 310         map_boot_text();
 311 #endif
 312 }
 313
 314 /* This is only called until mem_init is done. */
 315 void __init *early_get_page(void)
 316 {
 317         void *p;
 318
 319         if (init_bootmem_done) {
 320                 p = alloc_bootmem_pages(PAGE_SIZE);
 321         } else {
 322                 p = mem_pieces_find(PAGE_SIZE, PAGE_SIZE);
 323         }
 324         return p;
 325 }
 326
 327 /*
 328  * Initialize the bootmem system and give it all the memory we
 329  * have available.
 330  */
 331 void __init do_init_bootmem(void)
 332 {
 333         unsigned long start, size;
 334         int i;
 335
 336         /*
 337          * Find an area to use for the bootmem bitmap.
 338          * We look for the first area which is at least
 339          * 128kB in length (128kB is enough for a bitmap
 340          * for 4GB of memory, using 4kB pages), plus 1 page
 341          * (in case the address isn't page-aligned).
 342          */
 343         start = 0;
 344         size = 0;
 345         for (i = 0; i < phys_avail.n_regions; ++i) {
 346                 unsigned long a = phys_avail.regions[i].address;
 347                 unsigned long s = phys_avail.regions[i].size;
 348                 if (s <= size)
 349                         continue;
 350                 start = a;
 351                 size = s;
 352                 if (s >= 33 * PAGE_SIZE)
 353                         break;
 354         }
 355         start = PAGE_ALIGN(start);
 356
 357         min_low_pfn = start >> PAGE_SHIFT;
 358         max_low_pfn = (PPC_MEMSTART + total_lowmem) >> PAGE_SHIFT;
 359         max_pfn = (PPC_MEMSTART + total_memory) >> PAGE_SHIFT;
 360         boot_mapsize = init_bootmem_node(&contig_page_data, min_low_pfn,
 361                                          PPC_MEMSTART >> PAGE_SHIFT,
 362                                          max_low_pfn);
 363
 364         /* remove the bootmem bitmap from the available memory */
 365         mem_pieces_remove(&phys_avail, start, boot_mapsize, 1);
 366
 367         /* add everything in phys_avail into the bootmem map */
 368         for (i = 0; i < phys_avail.n_regions; ++i)
 369                 free_bootmem(phys_avail.regions[i].address,
 370                              phys_avail.regions[i].size);
 371
 372         init_bootmem_done = 1;
 373 }
 374
 375 /*
 376  * paging_init() sets up the page tables - in fact we've already done this.
 377  */
 378 void __init paging_init(void)
 379 {
 380         unsigned long zones_size[MAX_NR_ZONES], i;
 381
 382 #ifdef CONFIG_HIGHMEM
 383         map_page(PKMAP_BASE, 0, 0);     /* XXX gross */
 384         pkmap_page_table = pte_offset_kernel(pmd_offset(pgd_offset_k
 385                         (PKMAP_BASE), PKMAP_BASE), PKMAP_BASE);
 386         map_page(KMAP_FIX_BEGIN, 0, 0); /* XXX gross */
 387         kmap_pte = pte_offset_kernel(pmd_offset(pgd_offset_k
 388                         (KMAP_FIX_BEGIN), KMAP_FIX_BEGIN), KMAP_FIX_BEGIN);
 389         kmap_prot = PAGE_KERNEL;
 390 #endif /* CONFIG_HIGHMEM */
 391
 392         /*
 393          * All pages are DMA-able so we put them all in the DMA zone.
 394          */
 395         zones_size[ZONE_DMA] = total_lowmem >> PAGE_SHIFT;
 396         for (i = 1; i < MAX_NR_ZONES; i++)
 397                 zones_size[i] = 0;
 398
 399 #ifdef CONFIG_HIGHMEM
 400         zones_size[ZONE_HIGHMEM] = (total_memory - total_lowmem) >> PAGE_SHIFT;
 401 #endif /* CONFIG_HIGHMEM */
 402
 403         free_area_init(zones_size);
 404 }
 405
 406 void __init mem_init(void)
 407 {
 408         unsigned long addr;
 409         int codepages = 0;
 410         int datapages = 0;
 411         int initpages = 0;
 412 #ifdef CONFIG_HIGHMEM
 413         unsigned long highmem_mapnr;
 414
 415         highmem_mapnr = total_lowmem >> PAGE_SHIFT;
 416 #endif /* CONFIG_HIGHMEM */
 417         max_mapnr = total_memory >> PAGE_SHIFT;
 418
 419         high_memory = (void *) __va(PPC_MEMSTART + total_lowmem);
 420         num_physpages = max_mapnr;      /* RAM is assumed contiguous */
 421
 422         totalram_pages += free_all_bootmem();
 423
 424 #ifdef CONFIG_BLK_DEV_INITRD
 425         /* if we are booted from BootX with an initial ramdisk,
 426            make sure the ramdisk pages aren't reserved. */
 427         if (initrd_start) {
 428                 for (addr = initrd_start; addr < initrd_end; addr += PAGE_SIZE)
 429                         ClearPageReserved(virt_to_page(addr));
 430         }
 431 #endif /* CONFIG_BLK_DEV_INITRD */
 432
 433 #ifdef CONFIG_PPC_OF
 434         /* mark the RTAS pages as reserved */
 435         if ( rtas_data )
 436                 for (addr = (ulong)__va(rtas_data);
 437                      addr < PAGE_ALIGN((ulong)__va(rtas_data)+rtas_size) ;
 438                      addr += PAGE_SIZE)
 439                         SetPageReserved(virt_to_page(addr));
 440 #endif
 441 #ifdef CONFIG_PPC_PMAC
 442         if (agp_special_page)
 443                 SetPageReserved(virt_to_page(agp_special_page));
 444 #endif
 445         if ( sysmap )
 446                 for (addr = (unsigned long)sysmap;
 447                      addr < PAGE_ALIGN((unsigned long)sysmap+sysmap_size) ;
 448                      addr += PAGE_SIZE)
 449                         SetPageReserved(virt_to_page(addr));
 450
 451         for (addr = PAGE_OFFSET; addr < (unsigned long)high_memory;
 452              addr += PAGE_SIZE) {
 453                 if (!PageReserved(virt_to_page(addr)))
 454                         continue;
 455                 if (addr < (ulong) etext)
 456                         codepages++;
 457                 else if (addr >= (unsigned long)&__init_begin
 458                          && addr < (unsigned long)&__init_end)
 459                         initpages++;
 460                 else if (addr < (ulong) klimit)
 461                         datapages++;
 462         }
 463
 464 #ifdef CONFIG_HIGHMEM
 465         {
 466                 unsigned long pfn;
 467
 468                 for (pfn = highmem_mapnr; pfn < max_mapnr; ++pfn) {
 469                         struct page *page = mem_map + pfn;
 470
 471                         ClearPageReserved(page);
 472                         set_bit(PG_highmem, &page->flags);
 473                         set_page_count(page, 1);
 474                         __free_page(page);
 475                         totalhigh_pages++;
 476                 }
 477                 totalram_pages += totalhigh_pages;
 478         }
 479 #endif /* CONFIG_HIGHMEM */
 480
 481         printk("Memory: %luk available (%dk kernel code, %dk data, %dk init, %ldk highmem)\n",
 482                (unsigned long)nr_free_pages()<< (PAGE_SHIFT-10),
 483                codepages<< (PAGE_SHIFT-10), datapages<< (PAGE_SHIFT-10),
 484                initpages<< (PAGE_SHIFT-10),
 485                (unsigned long) (totalhigh_pages << (PAGE_SHIFT-10)));
 486         if (sysmap)
 487                 printk("System.map loaded at 0x%08x for debugger, size: %ld bytes\n",
 488                         (unsigned int)sysmap, sysmap_size);
 489 #ifdef CONFIG_PPC_PMAC
 490         if (agp_special_page)
 491                 printk(KERN_INFO "AGP special page: 0x%08lx\n", agp_special_page);
 492 #endif
 493
 494         mem_init_done = 1;
 495 }
 496
 497 /*
 498  * Set phys_avail to the amount of physical memory,
 499  * less the kernel text/data/bss.
 500  */
 501 void __init
 502 set_phys_avail(unsigned long total_memory)
 503 {
 504         unsigned long kstart, ksize;
 505
 506         /*
 507          * Initially, available physical memory is equivalent to all
 508          * physical memory.
 509          */
 510
 511         phys_avail.regions[0].address = PPC_MEMSTART;
 512         phys_avail.regions[0].size = total_memory;
 513         phys_avail.n_regions = 1;
 514
 515         /*
 516          * Map out the kernel text/data/bss from the available physical
 517          * memory.
 518          */
 519
 520         kstart = __pa(_stext);  /* should be 0 */
 521         ksize = PAGE_ALIGN(klimit - _stext);
 522
 523         mem_pieces_remove(&phys_avail, kstart, ksize, 0);
 524         mem_pieces_remove(&phys_avail, 0, 0x4000, 0);
 525
 526 #if defined(CONFIG_BLK_DEV_INITRD)
 527         /* Remove the init RAM disk from the available memory. */
 528         if (initrd_start) {
 529                 mem_pieces_remove(&phys_avail, __pa(initrd_start),
 530                                   initrd_end - initrd_start, 1);
 531         }
 532 #endif /* CONFIG_BLK_DEV_INITRD */
 533 #ifdef CONFIG_PPC_OF
 534         /* remove the RTAS pages from the available memory */
 535         if (rtas_data)
 536                 mem_pieces_remove(&phys_avail, rtas_data, rtas_size, 1);
 537 #endif
 538         /* remove the sysmap pages from the available memory */
 539         if (sysmap)
 540                 mem_pieces_remove(&phys_avail, __pa(sysmap), sysmap_size, 1);
 541 #ifdef CONFIG_PPC_PMAC
 542         /* Because of some uninorth weirdness, we need a page of
 543          * memory as high as possible (it must be outside of the
 544          * bus address seen as the AGP aperture). It will be used
 545          * by the r128 DRM driver
 546          *
 547          * FIXME: We need to make sure that page doesn't overlap any of the\
 548          * above. This could be done by improving mem_pieces_find to be able
 549          * to do a backward search from the end of the list.
 550          */
 551         if (_machine == _MACH_Pmac && find_devices("uni-north-agp")) {
 552                 agp_special_page = (total_memory - PAGE_SIZE);
 553                 mem_pieces_remove(&phys_avail, agp_special_page, PAGE_SIZE, 0);
 554                 agp_special_page = (unsigned long)__va(agp_special_page);
 555         }
 556 #endif /* CONFIG_PPC_PMAC */
 557 }
 558
 559 /* Mark some memory as reserved by removing it from phys_avail. */
 560 void __init reserve_phys_mem(unsigned long start, unsigned long size)
 561 {
 562         mem_pieces_remove(&phys_avail, start, size, 1);
 563 }
 564
 565 /*
 566  * This is called when a page has been modified by the kernel.
 567  * It just marks the page as not i-cache clean.  We do the i-cache
 568  * flush later when the page is given to a user process, if necessary.
 569  */
 570 void flush_dcache_page(struct page *page)
 571 {
 572         clear_bit(PG_arch_1, &page->flags);
 573 }
 574
 575 void flush_dcache_icache_page(struct page *page)
 576 {
 577 #ifdef CONFIG_BOOKE
 578         __flush_dcache_icache(kmap(page));
 579         kunmap(page);
 580 #else
 581         __flush_dcache_icache_phys(page_to_pfn(page) << PAGE_SHIFT);
 582 #endif
 583
 584 }
 585 void clear_user_page(void *page, unsigned long vaddr, struct page *pg)
 586 {
 587         clear_page(page);
 588         clear_bit(PG_arch_1, &pg->flags);
 589 }
 590
 591 void copy_user_page(void *vto, void *vfrom, unsigned long vaddr,
 592                     struct page *pg)
 593 {
 594         copy_page(vto, vfrom);
 595         clear_bit(PG_arch_1, &pg->flags);
 596 }
 597
 598 void flush_icache_user_range(struct vm_area_struct *vma, struct page *page,
 599                              unsigned long addr, int len)
 600 {
 601         unsigned long maddr;
 602
 603         maddr = (unsigned long) kmap(page) + (addr & ~PAGE_MASK);
 604         flush_icache_range(maddr, maddr + len);
 605         kunmap(page);
 606 }
 607
 608 /*
 609  * This is called at the end of handling a user page fault, when the
 610  * fault has been handled by updating a PTE in the linux page tables.
 611  * We use it to preload an HPTE into the hash table corresponding to
 612  * the updated linux PTE.
 613  */
 614 void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
 615                       pte_t pte)
 616 {
 617         /* handle i-cache coherency */
 618         unsigned long pfn = pte_pfn(pte);
 619
 620         if (pfn_valid(pfn)) {
 621                 struct page *page = pfn_to_page(pfn);
 622                 if (!PageReserved(page)
 623                     && !test_bit(PG_arch_1, &page->flags)) {
 624                         if (vma->vm_mm == current->active_mm)
 625                                 __flush_dcache_icache((void *) address);
 626                         else
 627                                 flush_dcache_icache_page(page);
 628                         set_bit(PG_arch_1, &page->flags);
 629                 }
 630         }
 631
 632 #ifdef CONFIG_PPC_STD_MMU
 633         /* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */
 634         if (Hash != 0 && pte_young(pte)) {
 635                 struct mm_struct *mm;
 636                 pmd_t *pmd;
 637
 638                 mm = (address < TASK_SIZE)? vma->vm_mm: &init_mm;
 639                 pmd = pmd_offset(pgd_offset(mm, address), address);
 640                 if (!pmd_none(*pmd))
 641                         add_hash_page(mm->context, address, pmd_val(*pmd));
 642         }
 643 #endif
 644 }
 645
 646 /*
 647  * This is called by /dev/mem to know if a given address has to
 648  * be mapped non-cacheable or not
 649  */
 650 int page_is_ram(unsigned long pfn)
 651 {
 652         unsigned long paddr = (pfn << PAGE_SHIFT);
 653
 654         return paddr < __pa(high_memory);
 655 }
 656
 657 pgprot_t phys_mem_access_prot(struct file *file, unsigned long addr,
 658                               unsigned long size, pgprot_t vma_prot)
 659 {
 660         if (ppc_md.phys_mem_access_prot)
 661                 return ppc_md.phys_mem_access_prot(file, addr, size, vma_prot);
 662
 663         if (!page_is_ram(addr >> PAGE_SHIFT))
 664                 vma_prot = __pgprot(pgprot_val(vma_prot)
 665                                     | _PAGE_GUARDED | _PAGE_NO_CACHE);
 666         return vma_prot;
 667 }
 668 EXPORT_SYMBOL(phys_mem_access_prot);