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         unsigned long addr;
 207         struct mmu_gather *tlb;
 208
 209         BUG_ON(seg >= 16);
 210
 211         /* Check no VMAs are in the region */
 212         vma = find_vma(mm, start);
 213         if (vma && (vma->vm_start < end))
 214                 return -EBUSY;
 215
 216         /* Clean up any leftover PTE pages in the region */
 217         spin_lock(&mm->page_table_lock);
 218         tlb = tlb_gather_mmu(mm, 0);
 219         for (addr = start; addr < end; addr += PMD_SIZE) {
 220                 pgd_t *pgd = pgd_offset(mm, addr);
 221                 pmd_t *pmd;
 222                 struct page *page;
 223                 pte_t *pte;
 224                 int i;
 225
 226                 if (pgd_none(*pgd))
 227                         continue;
 228                 pmd = pmd_offset(pgd, addr);
 229                 if (!pmd || pmd_none(*pmd))
 230                         continue;
 231                 if (pmd_bad(*pmd)) {
 232                         pmd_ERROR(*pmd);
 233                         pmd_clear(pmd);
 234                         continue;
 235                 }
 236                 pte = (pte_t *)pmd_page_kernel(*pmd);
 237                 /* No VMAs, so there should be no PTEs, check just in case. */
 238                 for (i = 0; i < PTRS_PER_PTE; i++) {
 239                         BUG_ON(!pte_none(*pte));
 240                         pte++;
 241                 }
 242                 page = pmd_page(*pmd);
 243                 pmd_clear(pmd);
 244                 mm->nr_ptes--;
 245                 dec_page_state(nr_page_table_pages);
 246                 pte_free_tlb(tlb, page);
 247         }
 248         tlb_finish_mmu(tlb, start, end);
 249         spin_unlock(&mm->page_table_lock);
 250
 251         return 0;
 252 }
 253
 254 static int open_low_hpage_segs(struct mm_struct *mm, u16 newsegs)
 255 {
 256         unsigned long i;
 257
 258         newsegs &= ~(mm->context.htlb_segs);
 259         if (! newsegs)
 260                 return 0; /* The segments we want are already open */
 261
 262         for (i = 0; i < 16; i++)
 263                 if ((1 << i) & newsegs)
 264                         if (prepare_low_seg_for_htlb(mm, i) != 0)
 265                                 return -EBUSY;
 266
 267         mm->context.htlb_segs |= newsegs;
 268
 269         /* update the paca copy of the context struct */
 270         get_paca()->context = mm->context;
 271
 272         /* the context change must make it to memory before the flush,
 273          * so that further SLB misses do the right thing. */
 274         mb();
 275         on_each_cpu(flush_segments, (void *)(unsigned long)newsegs, 0, 1);
 276
 277         return 0;
 278 }
 279
 280 int prepare_hugepage_range(unsigned long addr, unsigned long len)
 281 {
 282         if (within_hugepage_high_range(addr, len))
 283                 return 0;
 284         else if ((addr < 0x100000000UL) && ((addr+len) < 0x100000000UL)) {
 285                 int err;
 286                 /* Yes, we need both tests, in case addr+len overflows
 287                  * 64-bit arithmetic */
 288                 err = open_low_hpage_segs(current->mm,
 289                                           LOW_ESID_MASK(addr, len));
 290                 if (err)
 291                         printk(KERN_DEBUG "prepare_hugepage_range(%lx, %lx)"
 292                                " failed (segs: 0x%04hx)\n", addr, len,
 293                                LOW_ESID_MASK(addr, len));
 294                 return err;
 295         }
 296
 297         return -EINVAL;
 298 }
 299
 300 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 301                         struct vm_area_struct *vma)
 302 {
 303         pte_t *src_pte, *dst_pte, entry;
 304         struct page *ptepage;
 305         unsigned long addr = vma->vm_start;
 306         unsigned long end = vma->vm_end;
 307         int err = -ENOMEM;
 308
 309         while (addr < end) {
 310                 dst_pte = huge_pte_alloc(dst, addr);
 311                 if (!dst_pte)
 312                         goto out;
 313
 314                 src_pte = huge_pte_offset(src, addr);
 315                 entry = *src_pte;
 316
 317                 ptepage = pte_page(entry);
 318                 get_page(ptepage);
 319                 add_mm_counter(dst, rss, HPAGE_SIZE / PAGE_SIZE);
 320                 set_pte_at(dst, addr, dst_pte, entry);
 321
 322                 addr += HPAGE_SIZE;
 323         }
 324
 325         err = 0;
 326  out:
 327         return err;
 328 }
 329
 330 int
 331 follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 332                     struct page **pages, struct vm_area_struct **vmas,
 333                     unsigned long *position, int *length, int i)
 334 {
 335         unsigned long vpfn, vaddr = *position;
 336         int remainder = *length;
 337
 338         WARN_ON(!is_vm_hugetlb_page(vma));
 339
 340         vpfn = vaddr/PAGE_SIZE;
 341         while (vaddr < vma->vm_end && remainder) {
 342                 if (pages) {
 343                         pte_t *pte;
 344                         struct page *page;
 345
 346                         pte = huge_pte_offset(mm, vaddr);
 347
 348                         /* hugetlb should be locked, and hence, prefaulted */
 349                         WARN_ON(!pte || pte_none(*pte));
 350
 351                         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
 352
 353                         WARN_ON(!PageCompound(page));
 354
 355                         get_page(page);
 356                         pages[i] = page;
 357                 }
 358
 359                 if (vmas)
 360                         vmas[i] = vma;
 361
 362                 vaddr += PAGE_SIZE;
 363                 ++vpfn;
 364                 --remainder;
 365                 ++i;
 366         }
 367
 368         *length = remainder;
 369         *position = vaddr;
 370
 371         return i;
 372 }
 373
 374 struct page *
 375 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 376 {
 377         pte_t *ptep;
 378         struct page *page;
 379
 380         if (! in_hugepage_area(mm->context, address))
 381                 return ERR_PTR(-EINVAL);
 382
 383         ptep = huge_pte_offset(mm, address);
 384         page = pte_page(*ptep);
 385         if (page)
 386                 page += (address % HPAGE_SIZE) / PAGE_SIZE;
 387
 388         return page;
 389 }
 390
 391 int pmd_huge(pmd_t pmd)
 392 {
 393         return 0;
 394 }
 395
 396 struct page *
 397 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 398                 pmd_t *pmd, int write)
 399 {
 400         BUG();
 401         return NULL;
 402 }
 403
 404 void unmap_hugepage_range(struct vm_area_struct *vma,
 405                           unsigned long start, unsigned long end)
 406 {
 407         struct mm_struct *mm = vma->vm_mm;
 408         unsigned long addr;
 409         pte_t *ptep;
 410         struct page *page;
 411
 412         WARN_ON(!is_vm_hugetlb_page(vma));
 413         BUG_ON((start % HPAGE_SIZE) != 0);
 414         BUG_ON((end % HPAGE_SIZE) != 0);
 415
 416         for (addr = start; addr < end; addr += HPAGE_SIZE) {
 417                 pte_t pte;
 418
 419                 ptep = huge_pte_offset(mm, addr);
 420                 if (!ptep || pte_none(*ptep))
 421                         continue;
 422
 423                 pte = *ptep;
 424                 page = pte_page(pte);
 425                 pte_clear(mm, addr, ptep);
 426
 427                 put_page(page);
 428         }
 429         add_mm_counter(mm, rss, -((end - start) >> PAGE_SHIFT));
 430         flush_tlb_pending();
 431 }
 432
 433 void hugetlb_free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *prev,
 434                            unsigned long start, unsigned long end)
 435 {
 436         /* Because the huge pgtables are only 2 level, they can take
 437          * at most around 4M, much less than one hugepage which the
 438          * process is presumably entitled to use.  So we don't bother
 439          * freeing up the pagetables on unmap, and wait until
 440          * destroy_context() to clean up the lot. */
 441 }
 442
 443 int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma)
 444 {
 445         struct mm_struct *mm = current->mm;
 446         unsigned long addr;
 447         int ret = 0;
 448
 449         WARN_ON(!is_vm_hugetlb_page(vma));
 450         BUG_ON((vma->vm_start % HPAGE_SIZE) != 0);
 451         BUG_ON((vma->vm_end % HPAGE_SIZE) != 0);
 452
 453         spin_lock(&mm->page_table_lock);
 454         for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
 455                 unsigned long idx;
 456                 pte_t *pte = huge_pte_alloc(mm, addr);
 457                 struct page *page;
 458
 459                 if (!pte) {
 460                         ret = -ENOMEM;
 461                         goto out;
 462                 }
 463                 if (! pte_none(*pte))
 464                         continue;
 465
 466                 idx = ((addr - vma->vm_start) >> HPAGE_SHIFT)
 467                         + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
 468                 page = find_get_page(mapping, idx);
 469                 if (!page) {
 470                         /* charge the fs quota first */
 471                         if (hugetlb_get_quota(mapping)) {
 472                                 ret = -ENOMEM;
 473                                 goto out;
 474                         }
 475                         page = alloc_huge_page();
 476                         if (!page) {
 477                                 hugetlb_put_quota(mapping);
 478                                 ret = -ENOMEM;
 479                                 goto out;
 480                         }
 481                         ret = add_to_page_cache(page, mapping, idx, GFP_ATOMIC);
 482                         if (! ret) {
 483                                 unlock_page(page);
 484                         } else {
 485                                 hugetlb_put_quota(mapping);
 486                                 free_huge_page(page);
 487                                 goto out;
 488                         }
 489                 }
 490                 set_huge_pte(mm, vma, addr, page, pte, vma->vm_flags & VM_WRITE);
 491         }
 492 out:
 493         spin_unlock(&mm->page_table_lock);
 494         return ret;
 495 }
 496
 497 /* Because we have an exclusive hugepage region which lies within the
 498  * normal user address space, we have to take special measures to make
 499  * non-huge mmap()s evade the hugepage reserved regions. */
 500 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 501                                      unsigned long len, unsigned long pgoff,
 502                                      unsigned long flags)
 503 {
 504         struct mm_struct *mm = current->mm;
 505         struct vm_area_struct *vma;
 506         unsigned long start_addr;
 507
 508         if (len > TASK_SIZE)
 509                 return -ENOMEM;
 510
 511         if (addr) {
 512                 addr = PAGE_ALIGN(addr);
 513                 vma = find_vma(mm, addr);
 514                 if (((TASK_SIZE - len) >= addr)
 515                     && (!vma || (addr+len) <= vma->vm_start)
 516                     && !is_hugepage_only_range(mm, addr,len))
 517                         return addr;
 518         }
 519         start_addr = addr = mm->free_area_cache;
 520
 521 full_search:
 522         vma = find_vma(mm, addr);
 523         while (TASK_SIZE - len >= addr) {
 524                 BUG_ON(vma && (addr >= vma->vm_end));
 525
 526                 if (touches_hugepage_low_range(mm, addr, len)) {
 527                         addr = ALIGN(addr+1, 1<<SID_SHIFT);
 528                         vma = find_vma(mm, addr);
 529                         continue;
 530                 }
 531                 if (touches_hugepage_high_range(addr, len)) {
 532                         addr = TASK_HPAGE_END;
 533                         vma = find_vma(mm, addr);
 534                         continue;
 535                 }
 536                 if (!vma || addr + len <= vma->vm_start) {
 537                         /*
 538                          * Remember the place where we stopped the search:
 539                          */
 540                         mm->free_area_cache = addr + len;
 541                         return addr;
 542                 }
 543                 addr = vma->vm_end;
 544                 vma = vma->vm_next;
 545         }
 546
 547         /* Make sure we didn't miss any holes */
 548         if (start_addr != TASK_UNMAPPED_BASE) {
 549                 start_addr = addr = TASK_UNMAPPED_BASE;
 550                 goto full_search;
 551         }
 552         return -ENOMEM;
 553 }
 554
 555 /*
 556  * This mmap-allocator allocates new areas top-down from below the
 557  * stack's low limit (the base):
 558  *
 559  * Because we have an exclusive hugepage region which lies within the
 560  * normal user address space, we have to take special measures to make
 561  * non-huge mmap()s evade the hugepage reserved regions.
 562  */
 563 unsigned long
 564 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 565                           const unsigned long len, const unsigned long pgoff,
 566                           const unsigned long flags)
 567 {
 568         struct vm_area_struct *vma, *prev_vma;
 569         struct mm_struct *mm = current->mm;
 570         unsigned long base = mm->mmap_base, addr = addr0;
 571         int first_time = 1;
 572
 573         /* requested length too big for entire address space */
 574         if (len > TASK_SIZE)
 575                 return -ENOMEM;
 576
 577         /* dont allow allocations above current base */
 578         if (mm->free_area_cache > base)
 579                 mm->free_area_cache = base;
 580
 581         /* requesting a specific address */
 582         if (addr) {
 583                 addr = PAGE_ALIGN(addr);
 584                 vma = find_vma(mm, addr);
 585                 if (TASK_SIZE - len >= addr &&
 586                                 (!vma || addr + len <= vma->vm_start)
 587                                 && !is_hugepage_only_range(mm, addr,len))
 588                         return addr;
 589         }
 590
 591 try_again:
 592         /* make sure it can fit in the remaining address space */
 593         if (mm->free_area_cache < len)
 594                 goto fail;
 595
 596         /* either no address requested or cant fit in requested address hole */
 597         addr = (mm->free_area_cache - len) & PAGE_MASK;
 598         do {
 599 hugepage_recheck:
 600                 if (touches_hugepage_low_range(mm, addr, len)) {
 601                         addr = (addr & ((~0) << SID_SHIFT)) - len;
 602                         goto hugepage_recheck;
 603                 } else if (touches_hugepage_high_range(addr, len)) {
 604                         addr = TASK_HPAGE_BASE - len;
 605                 }
 606
 607                 /*
 608                  * Lookup failure means no vma is above this address,
 609                  * i.e. return with success:
 610                  */
 611                 if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
 612                         return addr;
 613
 614                 /*
 615                  * new region fits between prev_vma->vm_end and
 616                  * vma->vm_start, use it:
 617                  */
 618                 if (addr+len <= vma->vm_start &&
 619                                 (!prev_vma || (addr >= prev_vma->vm_end)))
 620                         /* remember the address as a hint for next time */
 621                         return (mm->free_area_cache = addr);
 622                 else
 623                         /* pull free_area_cache down to the first hole */
 624                         if (mm->free_area_cache == vma->vm_end)
 625                                 mm->free_area_cache = vma->vm_start;
 626
 627                 /* try just below the current vma->vm_start */
 628                 addr = vma->vm_start-len;
 629         } while (len <= vma->vm_start);
 630
 631 fail:
 632         /*
 633          * if hint left us with no space for the requested
 634          * mapping then try again:
 635          */
 636         if (first_time) {
 637                 mm->free_area_cache = base;
 638                 first_time = 0;
 639                 goto try_again;
 640         }
 641         /*
 642          * A failed mmap() very likely causes application failure,
 643          * so fall back to the bottom-up function here. This scenario
 644          * can happen with large stack limits and large mmap()
 645          * allocations.
 646          */
 647         mm->free_area_cache = TASK_UNMAPPED_BASE;
 648         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
 649         /*
 650          * Restore the topdown base:
 651          */
 652         mm->free_area_cache = base;
 653
 654         return addr;
 655 }
 656
 657 static unsigned long htlb_get_low_area(unsigned long len, u16 segmask)
 658 {
 659         unsigned long addr = 0;
 660         struct vm_area_struct *vma;
 661
 662         vma = find_vma(current->mm, addr);
 663         while (addr + len <= 0x100000000UL) {
 664                 BUG_ON(vma && (addr >= vma->vm_end)); /* invariant */
 665
 666                 if (! __within_hugepage_low_range(addr, len, segmask)) {
 667                         addr = ALIGN(addr+1, 1<<SID_SHIFT);
 668                         vma = find_vma(current->mm, addr);
 669                         continue;
 670                 }
 671
 672                 if (!vma || (addr + len) <= vma->vm_start)
 673                         return addr;
 674                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 675                 /* Depending on segmask this might not be a confirmed
 676                  * hugepage region, so the ALIGN could have skipped
 677                  * some VMAs */
 678                 vma = find_vma(current->mm, addr);
 679         }
 680
 681         return -ENOMEM;
 682 }
 683
 684 static unsigned long htlb_get_high_area(unsigned long len)
 685 {
 686         unsigned long addr = TASK_HPAGE_BASE;
 687         struct vm_area_struct *vma;
 688
 689         vma = find_vma(current->mm, addr);
 690         for (vma = find_vma(current->mm, addr);
 691              addr + len <= TASK_HPAGE_END;
 692              vma = vma->vm_next) {
 693                 BUG_ON(vma && (addr >= vma->vm_end)); /* invariant */
 694                 BUG_ON(! within_hugepage_high_range(addr, len));
 695
 696                 if (!vma || (addr + len) <= vma->vm_start)
 697                         return addr;
 698                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 699                 /* Because we're in a hugepage region, this alignment
 700                  * should not skip us over any VMAs */
 701         }
 702
 703         return -ENOMEM;
 704 }
 705
 706 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 707                                         unsigned long len, unsigned long pgoff,
 708                                         unsigned long flags)
 709 {
 710         if (len & ~HPAGE_MASK)
 711                 return -EINVAL;
 712
 713         if (!cpu_has_feature(CPU_FTR_16M_PAGE))
 714                 return -EINVAL;
 715
 716         if (test_thread_flag(TIF_32BIT)) {
 717                 int lastshift = 0;
 718                 u16 segmask, cursegs = current->mm->context.htlb_segs;
 719
 720                 /* First see if we can do the mapping in the existing
 721                  * low hpage segments */
 722                 addr = htlb_get_low_area(len, cursegs);
 723                 if (addr != -ENOMEM)
 724                         return addr;
 725
 726                 for (segmask = LOW_ESID_MASK(0x100000000UL-len, len);
 727                      ! lastshift; segmask >>=1) {
 728                         if (segmask & 1)
 729                                 lastshift = 1;
 730
 731                         addr = htlb_get_low_area(len, cursegs | segmask);
 732                         if ((addr != -ENOMEM)
 733                             && open_low_hpage_segs(current->mm, segmask) == 0)
 734                                 return addr;
 735                 }
 736                 printk(KERN_DEBUG "hugetlb_get_unmapped_area() unable to open"
 737                        " enough segments\n");
 738                 return -ENOMEM;
 739         } else {
 740                 return htlb_get_high_area(len);
 741         }
 742 }
 743
 744 void hugetlb_mm_free_pgd(struct mm_struct *mm)
 745 {
 746         int i;
 747         pgd_t *pgdir;
 748
 749         spin_lock(&mm->page_table_lock);
 750
 751         pgdir = mm->context.huge_pgdir;
 752         if (! pgdir)
 753                 goto out;
 754
 755         mm->context.huge_pgdir = NULL;
 756
 757         /* cleanup any hugepte pages leftover */
 758         for (i = 0; i < PTRS_PER_HUGEPGD; i++) {
 759                 pgd_t *pgd = pgdir + i;
 760
 761                 if (! pgd_none(*pgd)) {
 762                         pte_t *pte = (pte_t *)pgd_page(*pgd);
 763                         struct page *ptepage = virt_to_page(pte);
 764
 765                         ptepage->mapping = NULL;
 766
 767                         BUG_ON(memcmp(pte, empty_zero_page, PAGE_SIZE));
 768                         kmem_cache_free(zero_cache, pte);
 769                 }
 770                 pgd_clear(pgd);
 771         }
 772
 773         BUG_ON(memcmp(pgdir, empty_zero_page, PAGE_SIZE));
 774         kmem_cache_free(zero_cache, pgdir);
 775
 776  out:
 777         spin_unlock(&mm->page_table_lock);
 778 }
 779
 780 int hash_huge_page(struct mm_struct *mm, unsigned long access,
 781                    unsigned long ea, unsigned long vsid, int local)
 782 {
 783         pte_t *ptep;
 784         unsigned long va, vpn;
 785         pte_t old_pte, new_pte;
 786         unsigned long hpteflags, prpn;
 787         long slot;
 788         int err = 1;
 789
 790         spin_lock(&mm->page_table_lock);
 791
 792         ptep = huge_pte_offset(mm, ea);
 793
 794         /* Search the Linux page table for a match with va */
 795         va = (vsid << 28) | (ea & 0x0fffffff);
 796         vpn = va >> HPAGE_SHIFT;
 797
 798         /*
 799          * If no pte found or not present, send the problem up to
 800          * do_page_fault
 801          */
 802         if (unlikely(!ptep || pte_none(*ptep)))
 803                 goto out;
 804
 805 /*      BUG_ON(pte_bad(*ptep)); */
 806
 807         /*
 808          * Check the user's access rights to the page.  If access should be
 809          * prevented then send the problem up to do_page_fault.
 810          */
 811         if (unlikely(access & ~pte_val(*ptep)))
 812                 goto out;
 813         /*
 814          * At this point, we have a pte (old_pte) which can be used to build
 815          * or update an HPTE. There are 2 cases:
 816          *
 817          * 1. There is a valid (present) pte with no associated HPTE (this is
 818          *      the most common case)
 819          * 2. There is a valid (present) pte with an associated HPTE. The
 820          *      current values of the pp bits in the HPTE prevent access
 821          *      because we are doing software DIRTY bit management and the
 822          *      page is currently not DIRTY.
 823          */
 824
 825
 826         old_pte = *ptep;
 827         new_pte = old_pte;
 828
 829         hpteflags = 0x2 | (! (pte_val(new_pte) & _PAGE_RW));
 830         /* _PAGE_EXEC -> HW_NO_EXEC since it's inverted */
 831         hpteflags |= ((pte_val(new_pte) & _PAGE_EXEC) ? 0 : HW_NO_EXEC);
 832
 833         /* Check if pte already has an hpte (case 2) */
 834         if (unlikely(pte_val(old_pte) & _PAGE_HASHPTE)) {
 835                 /* There MIGHT be an HPTE for this pte */
 836                 unsigned long hash, slot;
 837
 838                 hash = hpt_hash(vpn, 1);
 839                 if (pte_val(old_pte) & _PAGE_SECONDARY)
 840                         hash = ~hash;
 841                 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 842                 slot += (pte_val(old_pte) & _PAGE_GROUP_IX) >> 12;
 843
 844                 if (ppc_md.hpte_updatepp(slot, hpteflags, va, 1, local) == -1)
 845                         pte_val(old_pte) &= ~_PAGE_HPTEFLAGS;
 846         }
 847
 848         if (likely(!(pte_val(old_pte) & _PAGE_HASHPTE))) {
 849                 unsigned long hash = hpt_hash(vpn, 1);
 850                 unsigned long hpte_group;
 851
 852                 prpn = pte_pfn(old_pte);
 853
 854 repeat:
 855                 hpte_group = ((hash & htab_hash_mask) *
 856                               HPTES_PER_GROUP) & ~0x7UL;
 857
 858                 /* Update the linux pte with the HPTE slot */
 859                 pte_val(new_pte) &= ~_PAGE_HPTEFLAGS;
 860                 pte_val(new_pte) |= _PAGE_HASHPTE;
 861
 862                 /* Add in WIMG bits */
 863                 /* XXX We should store these in the pte */
 864                 hpteflags |= _PAGE_COHERENT;
 865
 866                 slot = ppc_md.hpte_insert(hpte_group, va, prpn, 0,
 867                                           hpteflags, 0, 1);
 868
 869                 /* Primary is full, try the secondary */
 870                 if (unlikely(slot == -1)) {
 871                         pte_val(new_pte) |= _PAGE_SECONDARY;
 872                         hpte_group = ((~hash & htab_hash_mask) *
 873                                       HPTES_PER_GROUP) & ~0x7UL;
 874                         slot = ppc_md.hpte_insert(hpte_group, va, prpn,
 875                                                   1, hpteflags, 0, 1);
 876                         if (slot == -1) {
 877                                 if (mftb() & 0x1)
 878                                         hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 879
 880                                 ppc_md.hpte_remove(hpte_group);
 881                                 goto repeat;
 882                         }
 883                 }
 884
 885                 if (unlikely(slot == -2))
 886                         panic("hash_huge_page: pte_insert failed\n");
 887
 888                 pte_val(new_pte) |= (slot<<12) & _PAGE_GROUP_IX;
 889
 890                 /*
 891                  * No need to use ldarx/stdcx here because all who
 892                  * might be updating the pte will hold the
 893                  * page_table_lock
 894                  */
 895                 *ptep = new_pte;
 896         }
 897
 898         err = 0;
 899
 900  out:
 901         spin_unlock(&mm->page_table_lock);
 902
 903         return err;
 904 }