arch/ppc64/mm/hugetlbpage.c

   1 /*
   2  * PPC64 (POWER4) Huge TLB Page Support for Kernel.
   3  *
   4  * Copyright (C) 2003 David Gibson, IBM Corporation.
   5  *
   6  * Based on the IA-32 version:
   7  * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
   8  */
   9
  10 #include <linux/init.h>
  11 #include <linux/fs.h>
  12 #include <linux/mm.h>
  13 #include <linux/hugetlb.h>
  14 #include <linux/pagemap.h>
  15 #include <linux/smp_lock.h>
  16 #include <linux/slab.h>
  17 #include <linux/err.h>
  18 #include <linux/sysctl.h>
  19 #include <asm/mman.h>
  20 #include <asm/pgalloc.h>
  21 #include <asm/tlb.h>
  22 #include <asm/tlbflush.h>
  23 #include <asm/mmu_context.h>
  24 #include <asm/machdep.h>
  25 #include <asm/cputable.h>
  26 #include <asm/tlb.h>
  27
  28 #include <linux/sysctl.h>
  29
  30 #define HUGEPGDIR_SHIFT         (HPAGE_SHIFT + PAGE_SHIFT - 3)
  31 #define HUGEPGDIR_SIZE          (1UL << HUGEPGDIR_SHIFT)
  32 #define HUGEPGDIR_MASK          (~(HUGEPGDIR_SIZE-1))
  33
  34 #define HUGEPTE_INDEX_SIZE      9
  35 #define HUGEPGD_INDEX_SIZE      10
  36
  37 #define PTRS_PER_HUGEPTE        (1 << HUGEPTE_INDEX_SIZE)
  38 #define PTRS_PER_HUGEPGD        (1 << HUGEPGD_INDEX_SIZE)
  39
  40 static inline int hugepgd_index(unsigned long addr)
  41 {
  42         return (addr & ~REGION_MASK) >> HUGEPGDIR_SHIFT;
  43 }
  44
  45 static pgd_t *hugepgd_offset(struct mm_struct *mm, unsigned long addr)
  46 {
  47         int index;
  48
  49         if (! mm->context.huge_pgdir)
  50                 return NULL;
  51
  52
  53         index = hugepgd_index(addr);
  54         BUG_ON(index >= PTRS_PER_HUGEPGD);
  55         return mm->context.huge_pgdir + index;
  56 }
  57
  58 static inline pte_t *hugepte_offset(pgd_t *dir, unsigned long addr)
  59 {
  60         int index;
  61
  62         if (pgd_none(*dir))
  63                 return NULL;
  64
  65         index = (addr >> HPAGE_SHIFT) % PTRS_PER_HUGEPTE;
  66         return (pte_t *)pgd_page(*dir) + index;
  67 }
  68
  69 static pgd_t *hugepgd_alloc(struct mm_struct *mm, unsigned long addr)
  70 {
  71         BUG_ON(! in_hugepage_area(mm->context, addr));
  72
  73         if (! mm->context.huge_pgdir) {
  74                 pgd_t *new;
  75                 spin_unlock(&mm->page_table_lock);
  76                 /* Don't use pgd_alloc(), because we want __GFP_REPEAT */
  77                 new = kmem_cache_alloc(zero_cache, GFP_KERNEL | __GFP_REPEAT);
  78                 BUG_ON(memcmp(new, empty_zero_page, PAGE_SIZE));
  79                 spin_lock(&mm->page_table_lock);
  80
  81                 /*
  82                  * Because we dropped the lock, we should re-check the
  83                  * entry, as somebody else could have populated it..
  84                  */
  85                 if (mm->context.huge_pgdir)
  86                         pgd_free(new);
  87                 else
  88                         mm->context.huge_pgdir = new;
  89         }
  90         return hugepgd_offset(mm, addr);
  91 }
  92
  93 static pte_t *hugepte_alloc(struct mm_struct *mm, pgd_t *dir,
  94                             unsigned long addr)
  95 {
  96         if (! pgd_present(*dir)) {
  97                 pte_t *new;
  98
  99                 spin_unlock(&mm->page_table_lock);
 100                 new = kmem_cache_alloc(zero_cache, GFP_KERNEL | __GFP_REPEAT);
 101                 BUG_ON(memcmp(new, empty_zero_page, PAGE_SIZE));
 102                 spin_lock(&mm->page_table_lock);
 103                 /*
 104                  * Because we dropped the lock, we should re-check the
 105                  * entry, as somebody else could have populated it..
 106                  */
 107                 if (pgd_present(*dir)) {
 108                         if (new)
 109                                 kmem_cache_free(zero_cache, new);
 110                 } else {
 111                         struct page *ptepage;
 112
 113                         if (! new)
 114                                 return NULL;
 115                         ptepage = virt_to_page(new);
 116                         ptepage->mapping = (void *) mm;
 117                         ptepage->index = addr & HUGEPGDIR_MASK;
 118                         pgd_populate(mm, dir, new);
 119                 }
 120         }
 121
 122         return hugepte_offset(dir, addr);
 123 }
 124
 125 static pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
 126 {
 127         pgd_t *pgd;
 128
 129         BUG_ON(! in_hugepage_area(mm->context, addr));
 130
 131         pgd = hugepgd_offset(mm, addr);
 132         if (! pgd)
 133                 return NULL;
 134
 135         return hugepte_offset(pgd, addr);
 136 }
 137
 138 static pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr)
 139 {
 140         pgd_t *pgd;
 141
 142         BUG_ON(! in_hugepage_area(mm->context, addr));
 143
 144         pgd = hugepgd_alloc(mm, addr);
 145         if (! pgd)
 146                 return NULL;
 147
 148         return hugepte_alloc(mm, pgd, addr);
 149 }
 150
 151 static void set_huge_pte(struct mm_struct *mm, struct vm_area_struct *vma,
 152                          unsigned long addr, struct page *page,
 153                          pte_t *ptep, int write_access)
 154 {
 155         pte_t entry;
 156
 157         add_mm_counter(mm, rss, HPAGE_SIZE / PAGE_SIZE);
 158         if (write_access) {
 159                 entry =
 160                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
 161         } else {
 162                 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
 163         }
 164         entry = pte_mkyoung(entry);
 165         entry = pte_mkhuge(entry);
 166
 167         set_pte_at(mm, addr, ptep, entry);
 168 }
 169
 170 /*
 171  * This function checks for proper alignment of input addr and len parameters.
 172  */
 173 int is_aligned_hugepage_range(unsigned long addr, unsigned long len)
 174 {
 175         if (len & ~HPAGE_MASK)
 176                 return -EINVAL;
 177         if (addr & ~HPAGE_MASK)
 178                 return -EINVAL;
 179         if (! (within_hugepage_low_range(addr, len)
 180                || within_hugepage_high_range(addr, len)) )
 181                 return -EINVAL;
 182         return 0;
 183 }
 184
 185 static void flush_segments(void *parm)
 186 {
 187         u16 segs = (unsigned long) parm;
 188         unsigned long i;
 189
 190         asm volatile("isync" : : : "memory");
 191
 192         for (i = 0; i < 16; i++) {
 193                 if (! (segs & (1U << i)))
 194                         continue;
 195                 asm volatile("slbie %0" : : "r" (i << SID_SHIFT));
 196         }
 197
 198         asm volatile("isync" : : : "memory");
 199 }
 200
 201 static int prepare_low_seg_for_htlb(struct mm_struct *mm, unsigned long seg)
 202 {
 203         unsigned long start = seg << SID_SHIFT;
 204         unsigned long end = (seg+1) << SID_SHIFT;
 205         struct vm_area_struct *vma;
 206
 207         BUG_ON(seg >= 16);
 208
 209         /* Check no VMAs are in the region */
 210         vma = find_vma(mm, start);
 211         if (vma && (vma->vm_start < end))
 212                 return -EBUSY;
 213
 214         return 0;
 215 }
 216
 217 static int open_low_hpage_segs(struct mm_struct *mm, u16 newsegs)
 218 {
 219         unsigned long i;
 220
 221         newsegs &= ~(mm->context.htlb_segs);
 222         if (! newsegs)
 223                 return 0; /* The segments we want are already open */
 224
 225         for (i = 0; i < 16; i++)
 226                 if ((1 << i) & newsegs)
 227                         if (prepare_low_seg_for_htlb(mm, i) != 0)
 228                                 return -EBUSY;
 229
 230         mm->context.htlb_segs |= newsegs;
 231
 232         /* update the paca copy of the context struct */
 233         get_paca()->context = mm->context;
 234
 235         /* the context change must make it to memory before the flush,
 236          * so that further SLB misses do the right thing. */
 237         mb();
 238         on_each_cpu(flush_segments, (void *)(unsigned long)newsegs, 0, 1);
 239
 240         return 0;
 241 }
 242
 243 int prepare_hugepage_range(unsigned long addr, unsigned long len)
 244 {
 245         if (within_hugepage_high_range(addr, len))
 246                 return 0;
 247         else if ((addr < 0x100000000UL) && ((addr+len) < 0x100000000UL)) {
 248                 int err;
 249                 /* Yes, we need both tests, in case addr+len overflows
 250                  * 64-bit arithmetic */
 251                 err = open_low_hpage_segs(current->mm,
 252                                           LOW_ESID_MASK(addr, len));
 253                 if (err)
 254                         printk(KERN_DEBUG "prepare_hugepage_range(%lx, %lx)"
 255                                " failed (segs: 0x%04hx)\n", addr, len,
 256                                LOW_ESID_MASK(addr, len));
 257                 return err;
 258         }
 259
 260         return -EINVAL;
 261 }
 262
 263 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 264                         struct vm_area_struct *vma)
 265 {
 266         pte_t *src_pte, *dst_pte, entry;
 267         struct page *ptepage;
 268         unsigned long addr = vma->vm_start;
 269         unsigned long end = vma->vm_end;
 270         int err = -ENOMEM;
 271
 272         while (addr < end) {
 273                 dst_pte = huge_pte_alloc(dst, addr);
 274                 if (!dst_pte)
 275                         goto out;
 276
 277                 src_pte = huge_pte_offset(src, addr);
 278                 entry = *src_pte;
 279
 280                 ptepage = pte_page(entry);
 281                 get_page(ptepage);
 282                 add_mm_counter(dst, rss, HPAGE_SIZE / PAGE_SIZE);
 283                 set_pte_at(dst, addr, dst_pte, entry);
 284
 285                 addr += HPAGE_SIZE;
 286         }
 287
 288         err = 0;
 289  out:
 290         return err;
 291 }
 292
 293 int
 294 follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 295                     struct page **pages, struct vm_area_struct **vmas,
 296                     unsigned long *position, int *length, int i)
 297 {
 298         unsigned long vpfn, vaddr = *position;
 299         int remainder = *length;
 300
 301         WARN_ON(!is_vm_hugetlb_page(vma));
 302
 303         vpfn = vaddr/PAGE_SIZE;
 304         while (vaddr < vma->vm_end && remainder) {
 305                 if (pages) {
 306                         pte_t *pte;
 307                         struct page *page;
 308
 309                         pte = huge_pte_offset(mm, vaddr);
 310
 311                         /* hugetlb should be locked, and hence, prefaulted */
 312                         WARN_ON(!pte || pte_none(*pte));
 313
 314                         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
 315
 316                         WARN_ON(!PageCompound(page));
 317
 318                         get_page(page);
 319                         pages[i] = page;
 320                 }
 321
 322                 if (vmas)
 323                         vmas[i] = vma;
 324
 325                 vaddr += PAGE_SIZE;
 326                 ++vpfn;
 327                 --remainder;
 328                 ++i;
 329         }
 330
 331         *length = remainder;
 332         *position = vaddr;
 333
 334         return i;
 335 }
 336
 337 struct page *
 338 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 339 {
 340         pte_t *ptep;
 341         struct page *page;
 342
 343         if (! in_hugepage_area(mm->context, address))
 344                 return ERR_PTR(-EINVAL);
 345
 346         ptep = huge_pte_offset(mm, address);
 347         page = pte_page(*ptep);
 348         if (page)
 349                 page += (address % HPAGE_SIZE) / PAGE_SIZE;
 350
 351         return page;
 352 }
 353
 354 int pmd_huge(pmd_t pmd)
 355 {
 356         return 0;
 357 }
 358
 359 struct page *
 360 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 361                 pmd_t *pmd, int write)
 362 {
 363         BUG();
 364         return NULL;
 365 }
 366
 367 void unmap_hugepage_range(struct vm_area_struct *vma,
 368                           unsigned long start, unsigned long end)
 369 {
 370         struct mm_struct *mm = vma->vm_mm;
 371         unsigned long addr;
 372         pte_t *ptep;
 373         struct page *page;
 374
 375         WARN_ON(!is_vm_hugetlb_page(vma));
 376         BUG_ON((start % HPAGE_SIZE) != 0);
 377         BUG_ON((end % HPAGE_SIZE) != 0);
 378
 379         for (addr = start; addr < end; addr += HPAGE_SIZE) {
 380                 pte_t pte;
 381
 382                 ptep = huge_pte_offset(mm, addr);
 383                 if (!ptep || pte_none(*ptep))
 384                         continue;
 385
 386                 pte = *ptep;
 387                 page = pte_page(pte);
 388                 pte_clear(mm, addr, ptep);
 389
 390                 put_page(page);
 391         }
 392         add_mm_counter(mm, rss, -((end - start) >> PAGE_SHIFT));
 393         flush_tlb_pending();
 394 }
 395
 396 int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma)
 397 {
 398         struct mm_struct *mm = current->mm;
 399         unsigned long addr;
 400         int ret = 0;
 401
 402         WARN_ON(!is_vm_hugetlb_page(vma));
 403         BUG_ON((vma->vm_start % HPAGE_SIZE) != 0);
 404         BUG_ON((vma->vm_end % HPAGE_SIZE) != 0);
 405
 406         spin_lock(&mm->page_table_lock);
 407         for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
 408                 unsigned long idx;
 409                 pte_t *pte = huge_pte_alloc(mm, addr);
 410                 struct page *page;
 411
 412                 if (!pte) {
 413                         ret = -ENOMEM;
 414                         goto out;
 415                 }
 416                 if (! pte_none(*pte))
 417                         continue;
 418
 419                 idx = ((addr - vma->vm_start) >> HPAGE_SHIFT)
 420                         + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
 421                 page = find_get_page(mapping, idx);
 422                 if (!page) {
 423                         /* charge the fs quota first */
 424                         if (hugetlb_get_quota(mapping)) {
 425                                 ret = -ENOMEM;
 426                                 goto out;
 427                         }
 428                         page = alloc_huge_page();
 429                         if (!page) {
 430                                 hugetlb_put_quota(mapping);
 431                                 ret = -ENOMEM;
 432                                 goto out;
 433                         }
 434                         ret = add_to_page_cache(page, mapping, idx, GFP_ATOMIC);
 435                         if (! ret) {
 436                                 unlock_page(page);
 437                         } else {
 438                                 hugetlb_put_quota(mapping);
 439                                 free_huge_page(page);
 440                                 goto out;
 441                         }
 442                 }
 443                 set_huge_pte(mm, vma, addr, page, pte, vma->vm_flags & VM_WRITE);
 444         }
 445 out:
 446         spin_unlock(&mm->page_table_lock);
 447         return ret;
 448 }
 449
 450 /* Because we have an exclusive hugepage region which lies within the
 451  * normal user address space, we have to take special measures to make
 452  * non-huge mmap()s evade the hugepage reserved regions. */
 453 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 454                                      unsigned long len, unsigned long pgoff,
 455                                      unsigned long flags)
 456 {
 457         struct mm_struct *mm = current->mm;
 458         struct vm_area_struct *vma;
 459         unsigned long start_addr;
 460
 461         if (len > TASK_SIZE)
 462                 return -ENOMEM;
 463
 464         if (addr) {
 465                 addr = PAGE_ALIGN(addr);
 466                 vma = find_vma(mm, addr);
 467                 if (((TASK_SIZE - len) >= addr)
 468                     && (!vma || (addr+len) <= vma->vm_start)
 469                     && !is_hugepage_only_range(mm, addr,len))
 470                         return addr;
 471         }
 472         start_addr = addr = mm->free_area_cache;
 473
 474 full_search:
 475         vma = find_vma(mm, addr);
 476         while (TASK_SIZE - len >= addr) {
 477                 BUG_ON(vma && (addr >= vma->vm_end));
 478
 479                 if (touches_hugepage_low_range(mm, addr, len)) {
 480                         addr = ALIGN(addr+1, 1<<SID_SHIFT);
 481                         vma = find_vma(mm, addr);
 482                         continue;
 483                 }
 484                 if (touches_hugepage_high_range(addr, len)) {
 485                         addr = TASK_HPAGE_END;
 486                         vma = find_vma(mm, addr);
 487                         continue;
 488                 }
 489                 if (!vma || addr + len <= vma->vm_start) {
 490                         /*
 491                          * Remember the place where we stopped the search:
 492                          */
 493                         mm->free_area_cache = addr + len;
 494                         return addr;
 495                 }
 496                 addr = vma->vm_end;
 497                 vma = vma->vm_next;
 498         }
 499
 500         /* Make sure we didn't miss any holes */
 501         if (start_addr != TASK_UNMAPPED_BASE) {
 502                 start_addr = addr = TASK_UNMAPPED_BASE;
 503                 goto full_search;
 504         }
 505         return -ENOMEM;
 506 }
 507
 508 /*
 509  * This mmap-allocator allocates new areas top-down from below the
 510  * stack's low limit (the base):
 511  *
 512  * Because we have an exclusive hugepage region which lies within the
 513  * normal user address space, we have to take special measures to make
 514  * non-huge mmap()s evade the hugepage reserved regions.
 515  */
 516 unsigned long
 517 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 518                           const unsigned long len, const unsigned long pgoff,
 519                           const unsigned long flags)
 520 {
 521         struct vm_area_struct *vma, *prev_vma;
 522         struct mm_struct *mm = current->mm;
 523         unsigned long base = mm->mmap_base, addr = addr0;
 524         int first_time = 1;
 525
 526         /* requested length too big for entire address space */
 527         if (len > TASK_SIZE)
 528                 return -ENOMEM;
 529
 530         /* dont allow allocations above current base */
 531         if (mm->free_area_cache > base)
 532                 mm->free_area_cache = base;
 533
 534         /* requesting a specific address */
 535         if (addr) {
 536                 addr = PAGE_ALIGN(addr);
 537                 vma = find_vma(mm, addr);
 538                 if (TASK_SIZE - len >= addr &&
 539                                 (!vma || addr + len <= vma->vm_start)
 540                                 && !is_hugepage_only_range(mm, addr,len))
 541                         return addr;
 542         }
 543
 544 try_again:
 545         /* make sure it can fit in the remaining address space */
 546         if (mm->free_area_cache < len)
 547                 goto fail;
 548
 549         /* either no address requested or cant fit in requested address hole */
 550         addr = (mm->free_area_cache - len) & PAGE_MASK;
 551         do {
 552 hugepage_recheck:
 553                 if (touches_hugepage_low_range(mm, addr, len)) {
 554                         addr = (addr & ((~0) << SID_SHIFT)) - len;
 555                         goto hugepage_recheck;
 556                 } else if (touches_hugepage_high_range(addr, len)) {
 557                         addr = TASK_HPAGE_BASE - len;
 558                 }
 559
 560                 /*
 561                  * Lookup failure means no vma is above this address,
 562                  * i.e. return with success:
 563                  */
 564                 if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
 565                         return addr;
 566
 567                 /*
 568                  * new region fits between prev_vma->vm_end and
 569                  * vma->vm_start, use it:
 570                  */
 571                 if (addr+len <= vma->vm_start &&
 572                                 (!prev_vma || (addr >= prev_vma->vm_end)))
 573                         /* remember the address as a hint for next time */
 574                         return (mm->free_area_cache = addr);
 575                 else
 576                         /* pull free_area_cache down to the first hole */
 577                         if (mm->free_area_cache == vma->vm_end)
 578                                 mm->free_area_cache = vma->vm_start;
 579
 580                 /* try just below the current vma->vm_start */
 581                 addr = vma->vm_start-len;
 582         } while (len <= vma->vm_start);
 583
 584 fail:
 585         /*
 586          * if hint left us with no space for the requested
 587          * mapping then try again:
 588          */
 589         if (first_time) {
 590                 mm->free_area_cache = base;
 591                 first_time = 0;
 592                 goto try_again;
 593         }
 594         /*
 595          * A failed mmap() very likely causes application failure,
 596          * so fall back to the bottom-up function here. This scenario
 597          * can happen with large stack limits and large mmap()
 598          * allocations.
 599          */
 600         mm->free_area_cache = TASK_UNMAPPED_BASE;
 601         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
 602         /*
 603          * Restore the topdown base:
 604          */
 605         mm->free_area_cache = base;
 606
 607         return addr;
 608 }
 609
 610 static unsigned long htlb_get_low_area(unsigned long len, u16 segmask)
 611 {
 612         unsigned long addr = 0;
 613         struct vm_area_struct *vma;
 614
 615         vma = find_vma(current->mm, addr);
 616         while (addr + len <= 0x100000000UL) {
 617                 BUG_ON(vma && (addr >= vma->vm_end)); /* invariant */
 618
 619                 if (! __within_hugepage_low_range(addr, len, segmask)) {
 620                         addr = ALIGN(addr+1, 1<<SID_SHIFT);
 621                         vma = find_vma(current->mm, addr);
 622                         continue;
 623                 }
 624
 625                 if (!vma || (addr + len) <= vma->vm_start)
 626                         return addr;
 627                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 628                 /* Depending on segmask this might not be a confirmed
 629                  * hugepage region, so the ALIGN could have skipped
 630                  * some VMAs */
 631                 vma = find_vma(current->mm, addr);
 632         }
 633
 634         return -ENOMEM;
 635 }
 636
 637 static unsigned long htlb_get_high_area(unsigned long len)
 638 {
 639         unsigned long addr = TASK_HPAGE_BASE;
 640         struct vm_area_struct *vma;
 641
 642         vma = find_vma(current->mm, addr);
 643         for (vma = find_vma(current->mm, addr);
 644              addr + len <= TASK_HPAGE_END;
 645              vma = vma->vm_next) {
 646                 BUG_ON(vma && (addr >= vma->vm_end)); /* invariant */
 647                 BUG_ON(! within_hugepage_high_range(addr, len));
 648
 649                 if (!vma || (addr + len) <= vma->vm_start)
 650                         return addr;
 651                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 652                 /* Because we're in a hugepage region, this alignment
 653                  * should not skip us over any VMAs */
 654         }
 655
 656         return -ENOMEM;
 657 }
 658
 659 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 660                                         unsigned long len, unsigned long pgoff,
 661                                         unsigned long flags)
 662 {
 663         if (len & ~HPAGE_MASK)
 664                 return -EINVAL;
 665
 666         if (!cpu_has_feature(CPU_FTR_16M_PAGE))
 667                 return -EINVAL;
 668
 669         if (test_thread_flag(TIF_32BIT)) {
 670                 int lastshift = 0;
 671                 u16 segmask, cursegs = current->mm->context.htlb_segs;
 672
 673                 /* First see if we can do the mapping in the existing
 674                  * low hpage segments */
 675                 addr = htlb_get_low_area(len, cursegs);
 676                 if (addr != -ENOMEM)
 677                         return addr;
 678
 679                 for (segmask = LOW_ESID_MASK(0x100000000UL-len, len);
 680                      ! lastshift; segmask >>=1) {
 681                         if (segmask & 1)
 682                                 lastshift = 1;
 683
 684                         addr = htlb_get_low_area(len, cursegs | segmask);
 685                         if ((addr != -ENOMEM)
 686                             && open_low_hpage_segs(current->mm, segmask) == 0)
 687                                 return addr;
 688                 }
 689                 printk(KERN_DEBUG "hugetlb_get_unmapped_area() unable to open"
 690                        " enough segments\n");
 691                 return -ENOMEM;
 692         } else {
 693                 return htlb_get_high_area(len);
 694         }
 695 }
 696
 697 void hugetlb_mm_free_pgd(struct mm_struct *mm)
 698 {
 699         int i;
 700         pgd_t *pgdir;
 701
 702         spin_lock(&mm->page_table_lock);
 703
 704         pgdir = mm->context.huge_pgdir;
 705         if (! pgdir)
 706                 goto out;
 707
 708         mm->context.huge_pgdir = NULL;
 709
 710         /* cleanup any hugepte pages leftover */
 711         for (i = 0; i < PTRS_PER_HUGEPGD; i++) {
 712                 pgd_t *pgd = pgdir + i;
 713
 714                 if (! pgd_none(*pgd)) {
 715                         pte_t *pte = (pte_t *)pgd_page(*pgd);
 716                         struct page *ptepage = virt_to_page(pte);
 717
 718                         ptepage->mapping = NULL;
 719
 720                         BUG_ON(memcmp(pte, empty_zero_page, PAGE_SIZE));
 721                         kmem_cache_free(zero_cache, pte);
 722                 }
 723                 pgd_clear(pgd);
 724         }
 725
 726         BUG_ON(memcmp(pgdir, empty_zero_page, PAGE_SIZE));
 727         kmem_cache_free(zero_cache, pgdir);
 728
 729  out:
 730         spin_unlock(&mm->page_table_lock);
 731 }
 732
 733 int hash_huge_page(struct mm_struct *mm, unsigned long access,
 734                    unsigned long ea, unsigned long vsid, int local)
 735 {
 736         pte_t *ptep;
 737         unsigned long va, vpn;
 738         pte_t old_pte, new_pte;
 739         unsigned long hpteflags, prpn;
 740         long slot;
 741         int err = 1;
 742
 743         spin_lock(&mm->page_table_lock);
 744
 745         ptep = huge_pte_offset(mm, ea);
 746
 747         /* Search the Linux page table for a match with va */
 748         va = (vsid << 28) | (ea & 0x0fffffff);
 749         vpn = va >> HPAGE_SHIFT;
 750
 751         /*
 752          * If no pte found or not present, send the problem up to
 753          * do_page_fault
 754          */
 755         if (unlikely(!ptep || pte_none(*ptep)))
 756                 goto out;
 757
 758 /*      BUG_ON(pte_bad(*ptep)); */
 759
 760         /*
 761          * Check the user's access rights to the page.  If access should be
 762          * prevented then send the problem up to do_page_fault.
 763          */
 764         if (unlikely(access & ~pte_val(*ptep)))
 765                 goto out;
 766         /*
 767          * At this point, we have a pte (old_pte) which can be used to build
 768          * or update an HPTE. There are 2 cases:
 769          *
 770          * 1. There is a valid (present) pte with no associated HPTE (this is
 771          *      the most common case)
 772          * 2. There is a valid (present) pte with an associated HPTE. The
 773          *      current values of the pp bits in the HPTE prevent access
 774          *      because we are doing software DIRTY bit management and the
 775          *      page is currently not DIRTY.
 776          */
 777
 778
 779         old_pte = *ptep;
 780         new_pte = old_pte;
 781
 782         hpteflags = 0x2 | (! (pte_val(new_pte) & _PAGE_RW));
 783         /* _PAGE_EXEC -> HW_NO_EXEC since it's inverted */
 784         hpteflags |= ((pte_val(new_pte) & _PAGE_EXEC) ? 0 : HW_NO_EXEC);
 785
 786         /* Check if pte already has an hpte (case 2) */
 787         if (unlikely(pte_val(old_pte) & _PAGE_HASHPTE)) {
 788                 /* There MIGHT be an HPTE for this pte */
 789                 unsigned long hash, slot;
 790
 791                 hash = hpt_hash(vpn, 1);
 792                 if (pte_val(old_pte) & _PAGE_SECONDARY)
 793                         hash = ~hash;
 794                 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 795                 slot += (pte_val(old_pte) & _PAGE_GROUP_IX) >> 12;
 796
 797                 if (ppc_md.hpte_updatepp(slot, hpteflags, va, 1, local) == -1)
 798                         pte_val(old_pte) &= ~_PAGE_HPTEFLAGS;
 799         }
 800
 801         if (likely(!(pte_val(old_pte) & _PAGE_HASHPTE))) {
 802                 unsigned long hash = hpt_hash(vpn, 1);
 803                 unsigned long hpte_group;
 804
 805                 prpn = pte_pfn(old_pte);
 806
 807 repeat:
 808                 hpte_group = ((hash & htab_hash_mask) *
 809                               HPTES_PER_GROUP) & ~0x7UL;
 810
 811                 /* Update the linux pte with the HPTE slot */
 812                 pte_val(new_pte) &= ~_PAGE_HPTEFLAGS;
 813                 pte_val(new_pte) |= _PAGE_HASHPTE;
 814
 815                 /* Add in WIMG bits */
 816                 /* XXX We should store these in the pte */
 817                 hpteflags |= _PAGE_COHERENT;
 818
 819                 slot = ppc_md.hpte_insert(hpte_group, va, prpn, 0,
 820                                           hpteflags, 0, 1);
 821
 822                 /* Primary is full, try the secondary */
 823                 if (unlikely(slot == -1)) {
 824                         pte_val(new_pte) |= _PAGE_SECONDARY;
 825                         hpte_group = ((~hash & htab_hash_mask) *
 826                                       HPTES_PER_GROUP) & ~0x7UL;
 827                         slot = ppc_md.hpte_insert(hpte_group, va, prpn,
 828                                                   1, hpteflags, 0, 1);
 829                         if (slot == -1) {
 830                                 if (mftb() & 0x1)
 831                                         hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 832
 833                                 ppc_md.hpte_remove(hpte_group);
 834                                 goto repeat;
 835                         }
 836                 }
 837
 838                 if (unlikely(slot == -2))
 839                         panic("hash_huge_page: pte_insert failed\n");
 840
 841                 pte_val(new_pte) |= (slot<<12) & _PAGE_GROUP_IX;
 842
 843                 /*
 844                  * No need to use ldarx/stdcx here because all who
 845                  * might be updating the pte will hold the
 846                  * page_table_lock
 847                  */
 848                 *ptep = new_pte;
 849         }
 850
 851         err = 0;
 852
 853  out:
 854         spin_unlock(&mm->page_table_lock);
 855
 856         return err;
 857 }