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                          struct page *page, pte_t *ptep, int write_access)
 153 {
 154         pte_t entry;
 155
 156         mm->rss += (HPAGE_SIZE / PAGE_SIZE);
 157         if (write_access) {
 158                 entry =
 159                     pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
 160         } else {
 161                 entry = pte_wrprotect(mk_pte(page, vma->vm_page_prot));
 162         }
 163         entry = pte_mkyoung(entry);
 164         entry = pte_mkhuge(entry);
 165
 166         set_pte(ptep, entry);
 167 }
 168
 169 /*
 170  * This function checks for proper alignment of input addr and len parameters.
 171  */
 172 int is_aligned_hugepage_range(unsigned long addr, unsigned long len)
 173 {
 174         if (len & ~HPAGE_MASK)
 175                 return -EINVAL;
 176         if (addr & ~HPAGE_MASK)
 177                 return -EINVAL;
 178         if (! (within_hugepage_low_range(addr, len)
 179                || within_hugepage_high_range(addr, len)) )
 180                 return -EINVAL;
 181         return 0;
 182 }
 183
 184 static void flush_segments(void *parm)
 185 {
 186         u16 segs = (unsigned long) parm;
 187         unsigned long i;
 188
 189         asm volatile("isync" : : : "memory");
 190
 191         for (i = 0; i < 16; i++) {
 192                 if (! (segs & (1U << i)))
 193                         continue;
 194                 asm volatile("slbie %0" : : "r" (i << SID_SHIFT));
 195         }
 196
 197         asm volatile("isync" : : : "memory");
 198 }
 199
 200 static int prepare_low_seg_for_htlb(struct mm_struct *mm, unsigned long seg)
 201 {
 202         unsigned long start = seg << SID_SHIFT;
 203         unsigned long end = (seg+1) << SID_SHIFT;
 204         struct vm_area_struct *vma;
 205         unsigned long addr;
 206         struct mmu_gather *tlb;
 207
 208         BUG_ON(seg >= 16);
 209
 210         /* Check no VMAs are in the region */
 211         vma = find_vma(mm, start);
 212         if (vma && (vma->vm_start < end))
 213                 return -EBUSY;
 214
 215         /* Clean up any leftover PTE pages in the region */
 216         spin_lock(&mm->page_table_lock);
 217         tlb = tlb_gather_mmu(mm, 0);
 218         for (addr = start; addr < end; addr += PMD_SIZE) {
 219                 pgd_t *pgd = pgd_offset(mm, addr);
 220                 pmd_t *pmd;
 221                 struct page *page;
 222                 pte_t *pte;
 223                 int i;
 224
 225                 if (pgd_none(*pgd))
 226                         continue;
 227                 pmd = pmd_offset(pgd, addr);
 228                 if (!pmd || pmd_none(*pmd))
 229                         continue;
 230                 if (pmd_bad(*pmd)) {
 231                         pmd_ERROR(*pmd);
 232                         pmd_clear(pmd);
 233                         continue;
 234                 }
 235                 pte = (pte_t *)pmd_page_kernel(*pmd);
 236                 /* No VMAs, so there should be no PTEs, check just in case. */
 237                 for (i = 0; i < PTRS_PER_PTE; i++) {
 238                         BUG_ON(!pte_none(*pte));
 239                         pte++;
 240                 }
 241                 page = pmd_page(*pmd);
 242                 pmd_clear(pmd);
 243                 mm->nr_ptes--;
 244                 dec_page_state(nr_page_table_pages);
 245                 pte_free_tlb(tlb, page);
 246         }
 247         tlb_finish_mmu(tlb, start, end);
 248         spin_unlock(&mm->page_table_lock);
 249
 250         return 0;
 251 }
 252
 253 static int open_low_hpage_segs(struct mm_struct *mm, u16 newsegs)
 254 {
 255         unsigned long i;
 256
 257         newsegs &= ~(mm->context.htlb_segs);
 258         if (! newsegs)
 259                 return 0; /* The segments we want are already open */
 260
 261         for (i = 0; i < 16; i++)
 262                 if ((1 << i) & newsegs)
 263                         if (prepare_low_seg_for_htlb(mm, i) != 0)
 264                                 return -EBUSY;
 265
 266         mm->context.htlb_segs |= newsegs;
 267         /* the context change must make it to memory before the flush,
 268          * so that further SLB misses do the right thing. */
 269         mb();
 270         on_each_cpu(flush_segments, (void *)(unsigned long)newsegs, 0, 1);
 271
 272         return 0;
 273 }
 274
 275 int prepare_hugepage_range(unsigned long addr, unsigned long len)
 276 {
 277         if (within_hugepage_high_range(addr, len))
 278                 return 0;
 279         else if ((addr < 0x100000000UL) && ((addr+len) < 0x100000000UL)) {
 280                 int err;
 281                 /* Yes, we need both tests, in case addr+len overflows
 282                  * 64-bit arithmetic */
 283                 err = open_low_hpage_segs(current->mm,
 284                                           LOW_ESID_MASK(addr, len));
 285                 if (err)
 286                         printk(KERN_DEBUG "prepare_hugepage_range(%lx, %lx)"
 287                                " failed (segs: 0x%04hx)\n", addr, len,
 288                                LOW_ESID_MASK(addr, len));
 289                 return err;
 290         }
 291
 292         return -EINVAL;
 293 }
 294
 295 int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
 296                         struct vm_area_struct *vma)
 297 {
 298         pte_t *src_pte, *dst_pte, entry;
 299         struct page *ptepage;
 300         unsigned long addr = vma->vm_start;
 301         unsigned long end = vma->vm_end;
 302         int err = -ENOMEM;
 303
 304         while (addr < end) {
 305                 dst_pte = huge_pte_alloc(dst, addr);
 306                 if (!dst_pte)
 307                         goto out;
 308
 309                 src_pte = huge_pte_offset(src, addr);
 310                 entry = *src_pte;
 311
 312                 ptepage = pte_page(entry);
 313                 get_page(ptepage);
 314                 dst->rss += (HPAGE_SIZE / PAGE_SIZE);
 315                 set_pte(dst_pte, entry);
 316
 317                 addr += HPAGE_SIZE;
 318         }
 319
 320         err = 0;
 321  out:
 322         return err;
 323 }
 324
 325 int
 326 follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 327                     struct page **pages, struct vm_area_struct **vmas,
 328                     unsigned long *position, int *length, int i)
 329 {
 330         unsigned long vpfn, vaddr = *position;
 331         int remainder = *length;
 332
 333         WARN_ON(!is_vm_hugetlb_page(vma));
 334
 335         vpfn = vaddr/PAGE_SIZE;
 336         while (vaddr < vma->vm_end && remainder) {
 337                 if (pages) {
 338                         pte_t *pte;
 339                         struct page *page;
 340
 341                         pte = huge_pte_offset(mm, vaddr);
 342
 343                         /* hugetlb should be locked, and hence, prefaulted */
 344                         WARN_ON(!pte || pte_none(*pte));
 345
 346                         page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
 347
 348                         WARN_ON(!PageCompound(page));
 349
 350                         get_page(page);
 351                         pages[i] = page;
 352                 }
 353
 354                 if (vmas)
 355                         vmas[i] = vma;
 356
 357                 vaddr += PAGE_SIZE;
 358                 ++vpfn;
 359                 --remainder;
 360                 ++i;
 361         }
 362
 363         *length = remainder;
 364         *position = vaddr;
 365
 366         return i;
 367 }
 368
 369 struct page *
 370 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 371 {
 372         pte_t *ptep;
 373         struct page *page;
 374
 375         if (! in_hugepage_area(mm->context, address))
 376                 return ERR_PTR(-EINVAL);
 377
 378         ptep = huge_pte_offset(mm, address);
 379         page = pte_page(*ptep);
 380         if (page)
 381                 page += (address % HPAGE_SIZE) / PAGE_SIZE;
 382
 383         return page;
 384 }
 385
 386 int pmd_huge(pmd_t pmd)
 387 {
 388         return 0;
 389 }
 390
 391 struct page *
 392 follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 393                 pmd_t *pmd, int write)
 394 {
 395         BUG();
 396         return NULL;
 397 }
 398
 399 void unmap_hugepage_range(struct vm_area_struct *vma,
 400                           unsigned long start, unsigned long end)
 401 {
 402         struct mm_struct *mm = vma->vm_mm;
 403         unsigned long addr;
 404         pte_t *ptep;
 405         struct page *page;
 406
 407         WARN_ON(!is_vm_hugetlb_page(vma));
 408         BUG_ON((start % HPAGE_SIZE) != 0);
 409         BUG_ON((end % HPAGE_SIZE) != 0);
 410
 411         for (addr = start; addr < end; addr += HPAGE_SIZE) {
 412                 pte_t pte;
 413
 414                 ptep = huge_pte_offset(mm, addr);
 415                 if (!ptep || pte_none(*ptep))
 416                         continue;
 417
 418                 pte = *ptep;
 419                 page = pte_page(pte);
 420                 pte_clear(ptep);
 421
 422                 put_page(page);
 423         }
 424         mm->rss -= (end - start) >> PAGE_SHIFT;
 425         flush_tlb_pending();
 426 }
 427
 428 void hugetlb_free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *prev,
 429                            unsigned long start, unsigned long end)
 430 {
 431         /* Because the huge pgtables are only 2 level, they can take
 432          * at most around 4M, much less than one hugepage which the
 433          * process is presumably entitled to use.  So we don't bother
 434          * freeing up the pagetables on unmap, and wait until
 435          * destroy_context() to clean up the lot. */
 436 }
 437
 438 int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma)
 439 {
 440         struct mm_struct *mm = current->mm;
 441         unsigned long addr;
 442         int ret = 0;
 443
 444         WARN_ON(!is_vm_hugetlb_page(vma));
 445         BUG_ON((vma->vm_start % HPAGE_SIZE) != 0);
 446         BUG_ON((vma->vm_end % HPAGE_SIZE) != 0);
 447
 448         spin_lock(&mm->page_table_lock);
 449         for (addr = vma->vm_start; addr < vma->vm_end; addr += HPAGE_SIZE) {
 450                 unsigned long idx;
 451                 pte_t *pte = huge_pte_alloc(mm, addr);
 452                 struct page *page;
 453
 454                 if (!pte) {
 455                         ret = -ENOMEM;
 456                         goto out;
 457                 }
 458                 if (! pte_none(*pte))
 459                         continue;
 460
 461                 idx = ((addr - vma->vm_start) >> HPAGE_SHIFT)
 462                         + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
 463                 page = find_get_page(mapping, idx);
 464                 if (!page) {
 465                         /* charge the fs quota first */
 466                         if (hugetlb_get_quota(mapping)) {
 467                                 ret = -ENOMEM;
 468                                 goto out;
 469                         }
 470                         page = alloc_huge_page();
 471                         if (!page) {
 472                                 hugetlb_put_quota(mapping);
 473                                 ret = -ENOMEM;
 474                                 goto out;
 475                         }
 476                         ret = add_to_page_cache(page, mapping, idx, GFP_ATOMIC);
 477                         if (! ret) {
 478                                 unlock_page(page);
 479                         } else {
 480                                 hugetlb_put_quota(mapping);
 481                                 free_huge_page(page);
 482                                 goto out;
 483                         }
 484                 }
 485                 set_huge_pte(mm, vma, page, pte, vma->vm_flags & VM_WRITE);
 486         }
 487 out:
 488         spin_unlock(&mm->page_table_lock);
 489         return ret;
 490 }
 491
 492 /* Because we have an exclusive hugepage region which lies within the
 493  * normal user address space, we have to take special measures to make
 494  * non-huge mmap()s evade the hugepage reserved regions. */
 495 unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
 496                                      unsigned long len, unsigned long pgoff,
 497                                      unsigned long flags)
 498 {
 499         struct mm_struct *mm = current->mm;
 500         struct vm_area_struct *vma;
 501         unsigned long start_addr;
 502
 503         if (len > TASK_SIZE)
 504                 return -ENOMEM;
 505
 506         if (addr) {
 507                 addr = PAGE_ALIGN(addr);
 508                 vma = find_vma(mm, addr);
 509                 if (((TASK_SIZE - len) >= addr)
 510                     && (!vma || (addr+len) <= vma->vm_start)
 511                     && !is_hugepage_only_range(addr,len))
 512                         return addr;
 513         }
 514         start_addr = addr = mm->free_area_cache;
 515
 516 full_search:
 517         vma = find_vma(mm, addr);
 518         while (TASK_SIZE - len >= addr) {
 519                 BUG_ON(vma && (addr >= vma->vm_end));
 520
 521                 if (touches_hugepage_low_range(addr, len)) {
 522                         addr = ALIGN(addr+1, 1<<SID_SHIFT);
 523                         vma = find_vma(mm, addr);
 524                         continue;
 525                 }
 526                 if (touches_hugepage_high_range(addr, len)) {
 527                         addr = TASK_HPAGE_END;
 528                         vma = find_vma(mm, addr);
 529                         continue;
 530                 }
 531                 if (!vma || addr + len <= vma->vm_start) {
 532                         /*
 533                          * Remember the place where we stopped the search:
 534                          */
 535                         mm->free_area_cache = addr + len;
 536                         return addr;
 537                 }
 538                 addr = vma->vm_end;
 539                 vma = vma->vm_next;
 540         }
 541
 542         /* Make sure we didn't miss any holes */
 543         if (start_addr != TASK_UNMAPPED_BASE) {
 544                 start_addr = addr = TASK_UNMAPPED_BASE;
 545                 goto full_search;
 546         }
 547         return -ENOMEM;
 548 }
 549
 550 /*
 551  * This mmap-allocator allocates new areas top-down from below the
 552  * stack's low limit (the base):
 553  *
 554  * Because we have an exclusive hugepage region which lies within the
 555  * normal user address space, we have to take special measures to make
 556  * non-huge mmap()s evade the hugepage reserved regions.
 557  */
 558 unsigned long
 559 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
 560                           const unsigned long len, const unsigned long pgoff,
 561                           const unsigned long flags)
 562 {
 563         struct vm_area_struct *vma, *prev_vma;
 564         struct mm_struct *mm = current->mm;
 565         unsigned long base = mm->mmap_base, addr = addr0;
 566         int first_time = 1;
 567
 568         /* requested length too big for entire address space */
 569         if (len > TASK_SIZE)
 570                 return -ENOMEM;
 571
 572         /* dont allow allocations above current base */
 573         if (mm->free_area_cache > base)
 574                 mm->free_area_cache = base;
 575
 576         /* requesting a specific address */
 577         if (addr) {
 578                 addr = PAGE_ALIGN(addr);
 579                 vma = find_vma(mm, addr);
 580                 if (TASK_SIZE - len >= addr &&
 581                                 (!vma || addr + len <= vma->vm_start)
 582                                 && !is_hugepage_only_range(addr,len))
 583                         return addr;
 584         }
 585
 586 try_again:
 587         /* make sure it can fit in the remaining address space */
 588         if (mm->free_area_cache < len)
 589                 goto fail;
 590
 591         /* either no address requested or cant fit in requested address hole */
 592         addr = (mm->free_area_cache - len) & PAGE_MASK;
 593         do {
 594 hugepage_recheck:
 595                 if (touches_hugepage_low_range(addr, len)) {
 596                         addr = (addr & ((~0) << SID_SHIFT)) - len;
 597                         goto hugepage_recheck;
 598                 } else if (touches_hugepage_high_range(addr, len)) {
 599                         addr = TASK_HPAGE_BASE - len;
 600                 }
 601
 602                 /*
 603                  * Lookup failure means no vma is above this address,
 604                  * i.e. return with success:
 605                  */
 606                 if (!(vma = find_vma_prev(mm, addr, &prev_vma)))
 607                         return addr;
 608
 609                 /*
 610                  * new region fits between prev_vma->vm_end and
 611                  * vma->vm_start, use it:
 612                  */
 613                 if (addr+len <= vma->vm_start &&
 614                                 (!prev_vma || (addr >= prev_vma->vm_end)))
 615                         /* remember the address as a hint for next time */
 616                         return (mm->free_area_cache = addr);
 617                 else
 618                         /* pull free_area_cache down to the first hole */
 619                         if (mm->free_area_cache == vma->vm_end)
 620                                 mm->free_area_cache = vma->vm_start;
 621
 622                 /* try just below the current vma->vm_start */
 623                 addr = vma->vm_start-len;
 624         } while (len <= vma->vm_start);
 625
 626 fail:
 627         /*
 628          * if hint left us with no space for the requested
 629          * mapping then try again:
 630          */
 631         if (first_time) {
 632                 mm->free_area_cache = base;
 633                 first_time = 0;
 634                 goto try_again;
 635         }
 636         /*
 637          * A failed mmap() very likely causes application failure,
 638          * so fall back to the bottom-up function here. This scenario
 639          * can happen with large stack limits and large mmap()
 640          * allocations.
 641          */
 642         mm->free_area_cache = TASK_UNMAPPED_BASE;
 643         addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
 644         /*
 645          * Restore the topdown base:
 646          */
 647         mm->free_area_cache = base;
 648
 649         return addr;
 650 }
 651
 652 static unsigned long htlb_get_low_area(unsigned long len, u16 segmask)
 653 {
 654         unsigned long addr = 0;
 655         struct vm_area_struct *vma;
 656
 657         vma = find_vma(current->mm, addr);
 658         while (addr + len <= 0x100000000UL) {
 659                 BUG_ON(vma && (addr >= vma->vm_end)); /* invariant */
 660
 661                 if (! __within_hugepage_low_range(addr, len, segmask)) {
 662                         addr = ALIGN(addr+1, 1<<SID_SHIFT);
 663                         vma = find_vma(current->mm, addr);
 664                         continue;
 665                 }
 666
 667                 if (!vma || (addr + len) <= vma->vm_start)
 668                         return addr;
 669                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 670                 /* Depending on segmask this might not be a confirmed
 671                  * hugepage region, so the ALIGN could have skipped
 672                  * some VMAs */
 673                 vma = find_vma(current->mm, addr);
 674         }
 675
 676         return -ENOMEM;
 677 }
 678
 679 static unsigned long htlb_get_high_area(unsigned long len)
 680 {
 681         unsigned long addr = TASK_HPAGE_BASE;
 682         struct vm_area_struct *vma;
 683
 684         vma = find_vma(current->mm, addr);
 685         for (vma = find_vma(current->mm, addr);
 686              addr + len <= TASK_HPAGE_END;
 687              vma = vma->vm_next) {
 688                 BUG_ON(vma && (addr >= vma->vm_end)); /* invariant */
 689                 BUG_ON(! within_hugepage_high_range(addr, len));
 690
 691                 if (!vma || (addr + len) <= vma->vm_start)
 692                         return addr;
 693                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 694                 /* Because we're in a hugepage region, this alignment
 695                  * should not skip us over any VMAs */
 696         }
 697
 698         return -ENOMEM;
 699 }
 700
 701 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 702                                         unsigned long len, unsigned long pgoff,
 703                                         unsigned long flags)
 704 {
 705         if (len & ~HPAGE_MASK)
 706                 return -EINVAL;
 707
 708         if (!(cur_cpu_spec->cpu_features & CPU_FTR_16M_PAGE))
 709                 return -EINVAL;
 710
 711         if (test_thread_flag(TIF_32BIT)) {
 712                 int lastshift = 0;
 713                 u16 segmask, cursegs = current->mm->context.htlb_segs;
 714
 715                 /* First see if we can do the mapping in the existing
 716                  * low hpage segments */
 717                 addr = htlb_get_low_area(len, cursegs);
 718                 if (addr != -ENOMEM)
 719                         return addr;
 720
 721                 for (segmask = LOW_ESID_MASK(0x100000000UL-len, len);
 722                      ! lastshift; segmask >>=1) {
 723                         if (segmask & 1)
 724                                 lastshift = 1;
 725
 726                         addr = htlb_get_low_area(len, cursegs | segmask);
 727                         if ((addr != -ENOMEM)
 728                             && open_low_hpage_segs(current->mm, segmask) == 0)
 729                                 return addr;
 730                 }
 731                 printk(KERN_DEBUG "hugetlb_get_unmapped_area() unable to open"
 732                        " enough segments\n");
 733                 return -ENOMEM;
 734         } else {
 735                 return htlb_get_high_area(len);
 736         }
 737 }
 738
 739 void hugetlb_mm_free_pgd(struct mm_struct *mm)
 740 {
 741         int i;
 742         pgd_t *pgdir;
 743
 744         spin_lock(&mm->page_table_lock);
 745
 746         pgdir = mm->context.huge_pgdir;
 747         if (! pgdir)
 748                 goto out;
 749
 750         mm->context.huge_pgdir = NULL;
 751
 752         /* cleanup any hugepte pages leftover */
 753         for (i = 0; i < PTRS_PER_HUGEPGD; i++) {
 754                 pgd_t *pgd = pgdir + i;
 755
 756                 if (! pgd_none(*pgd)) {
 757                         pte_t *pte = (pte_t *)pgd_page(*pgd);
 758                         struct page *ptepage = virt_to_page(pte);
 759
 760                         ptepage->mapping = NULL;
 761
 762                         BUG_ON(memcmp(pte, empty_zero_page, PAGE_SIZE));
 763                         kmem_cache_free(zero_cache, pte);
 764                 }
 765                 pgd_clear(pgd);
 766         }
 767
 768         BUG_ON(memcmp(pgdir, empty_zero_page, PAGE_SIZE));
 769         kmem_cache_free(zero_cache, pgdir);
 770
 771  out:
 772         spin_unlock(&mm->page_table_lock);
 773 }
 774
 775 int hash_huge_page(struct mm_struct *mm, unsigned long access,
 776                    unsigned long ea, unsigned long vsid, int local)
 777 {
 778         pte_t *ptep;
 779         unsigned long va, vpn;
 780         int is_write;
 781         pte_t old_pte, new_pte;
 782         unsigned long hpteflags, prpn;
 783         long slot;
 784         int err = 1;
 785
 786         spin_lock(&mm->page_table_lock);
 787
 788         ptep = huge_pte_offset(mm, ea);
 789
 790         /* Search the Linux page table for a match with va */
 791         va = (vsid << 28) | (ea & 0x0fffffff);
 792         vpn = va >> HPAGE_SHIFT;
 793
 794         /*
 795          * If no pte found or not present, send the problem up to
 796          * do_page_fault
 797          */
 798         if (unlikely(!ptep || pte_none(*ptep)))
 799                 goto out;
 800
 801 /*      BUG_ON(pte_bad(*ptep)); */
 802
 803         /*
 804          * Check the user's access rights to the page.  If access should be
 805          * prevented then send the problem up to do_page_fault.
 806          */
 807         is_write = access & _PAGE_RW;
 808         if (unlikely(is_write && !(pte_val(*ptep) & _PAGE_RW)))
 809                 goto out;
 810         /*
 811          * At this point, we have a pte (old_pte) which can be used to build
 812          * or update an HPTE. There are 2 cases:
 813          *
 814          * 1. There is a valid (present) pte with no associated HPTE (this is
 815          *      the most common case)
 816          * 2. There is a valid (present) pte with an associated HPTE. The
 817          *      current values of the pp bits in the HPTE prevent access
 818          *      because we are doing software DIRTY bit management and the
 819          *      page is currently not DIRTY.
 820          */
 821
 822
 823         old_pte = *ptep;
 824         new_pte = old_pte;
 825
 826         hpteflags = 0x2 | (! (pte_val(new_pte) & _PAGE_RW));
 827
 828         /* Check if pte already has an hpte (case 2) */
 829         if (unlikely(pte_val(old_pte) & _PAGE_HASHPTE)) {
 830                 /* There MIGHT be an HPTE for this pte */
 831                 unsigned long hash, slot;
 832
 833                 hash = hpt_hash(vpn, 1);
 834                 if (pte_val(old_pte) & _PAGE_SECONDARY)
 835                         hash = ~hash;
 836                 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
 837                 slot += (pte_val(old_pte) & _PAGE_GROUP_IX) >> 12;
 838
 839                 if (ppc_md.hpte_updatepp(slot, hpteflags, va, 1, local) == -1)
 840                         pte_val(old_pte) &= ~_PAGE_HPTEFLAGS;
 841         }
 842
 843         if (likely(!(pte_val(old_pte) & _PAGE_HASHPTE))) {
 844                 unsigned long hash = hpt_hash(vpn, 1);
 845                 unsigned long hpte_group;
 846
 847                 prpn = pte_pfn(old_pte);
 848
 849 repeat:
 850                 hpte_group = ((hash & htab_hash_mask) *
 851                               HPTES_PER_GROUP) & ~0x7UL;
 852
 853                 /* Update the linux pte with the HPTE slot */
 854                 pte_val(new_pte) &= ~_PAGE_HPTEFLAGS;
 855                 pte_val(new_pte) |= _PAGE_HASHPTE;
 856
 857                 /* Add in WIMG bits */
 858                 /* XXX We should store these in the pte */
 859                 hpteflags |= _PAGE_COHERENT;
 860
 861                 slot = ppc_md.hpte_insert(hpte_group, va, prpn, 0,
 862                                           hpteflags, 0, 1);
 863
 864                 /* Primary is full, try the secondary */
 865                 if (unlikely(slot == -1)) {
 866                         pte_val(new_pte) |= _PAGE_SECONDARY;
 867                         hpte_group = ((~hash & htab_hash_mask) *
 868                                       HPTES_PER_GROUP) & ~0x7UL;
 869                         slot = ppc_md.hpte_insert(hpte_group, va, prpn,
 870                                                   1, hpteflags, 0, 1);
 871                         if (slot == -1) {
 872                                 if (mftb() & 0x1)
 873                                         hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
 874
 875                                 ppc_md.hpte_remove(hpte_group);
 876                                 goto repeat;
 877                         }
 878                 }
 879
 880                 if (unlikely(slot == -2))
 881                         panic("hash_huge_page: pte_insert failed\n");
 882
 883                 pte_val(new_pte) |= (slot<<12) & _PAGE_GROUP_IX;
 884
 885                 /*
 886                  * No need to use ldarx/stdcx here because all who
 887                  * might be updating the pte will hold the
 888                  * page_table_lock
 889                  */
 890                 *ptep = new_pte;
 891         }
 892
 893         err = 0;
 894
 895  out:
 896         spin_unlock(&mm->page_table_lock);
 897
 898         return err;
 899 }