arch/powerpc/mm/hugetlbpage.c

   1 /*
   2  * PPC Huge TLB Page Support for Kernel.
   3  *
   4  * Copyright (C) 2003 David Gibson, IBM Corporation.
   5  * Copyright (C) 2011 Becky Bruce, Freescale Semiconductor
   6  *
   7  * Based on the IA-32 version:
   8  * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
   9  */
  10
  11 #include <linux/mm.h>
  12 #include <linux/io.h>
  13 #include <linux/slab.h>
  14 #include <linux/hugetlb.h>
  15 #include <linux/export.h>
  16 #include <linux/of_fdt.h>
  17 #include <linux/memblock.h>
  18 #include <linux/bootmem.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/swap.h>
  21 #include <linux/swapops.h>
  22 #include <asm/pgtable.h>
  23 #include <asm/pgalloc.h>
  24 #include <asm/tlb.h>
  25 #include <asm/setup.h>
  26 #include <asm/hugetlb.h>
  27 #include <asm/pte-walk.h>
  28
  29
  30 #ifdef CONFIG_HUGETLB_PAGE
  31
  32 #define PAGE_SHIFT_64K  16
  33 #define PAGE_SHIFT_512K 19
  34 #define PAGE_SHIFT_8M   23
  35 #define PAGE_SHIFT_16M  24
  36 #define PAGE_SHIFT_16G  34
  37
  38 bool hugetlb_disabled = false;
  39
  40 unsigned int HPAGE_SHIFT;
  41 EXPORT_SYMBOL(HPAGE_SHIFT);
  42
  43 #define hugepd_none(hpd)        (hpd_val(hpd) == 0)
  44
  45 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long sz)
  46 {
  47         /*
  48          * Only called for hugetlbfs pages, hence can ignore THP and the
  49          * irq disabled walk.
  50          */
  51         return __find_linux_pte(mm->pgd, addr, NULL, NULL);
  52 }
  53
  54 static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
  55                            unsigned long address, unsigned int pdshift,
  56                            unsigned int pshift, spinlock_t *ptl)
  57 {
  58         struct kmem_cache *cachep;
  59         pte_t *new;
  60         int i;
  61         int num_hugepd;
  62
  63         if (pshift >= pdshift) {
  64                 cachep = hugepte_cache;
  65                 num_hugepd = 1 << (pshift - pdshift);
  66         } else {
  67                 cachep = PGT_CACHE(pdshift - pshift);
  68                 num_hugepd = 1;
  69         }
  70
  71         new = kmem_cache_zalloc(cachep, pgtable_gfp_flags(mm, GFP_KERNEL));
  72
  73         BUG_ON(pshift > HUGEPD_SHIFT_MASK);
  74         BUG_ON((unsigned long)new & HUGEPD_SHIFT_MASK);
  75
  76         if (! new)
  77                 return -ENOMEM;
  78
  79         /*
  80          * Make sure other cpus find the hugepd set only after a
  81          * properly initialized page table is visible to them.
  82          * For more details look for comment in __pte_alloc().
  83          */
  84         smp_wmb();
  85
  86         spin_lock(ptl);
  87         /*
  88          * We have multiple higher-level entries that point to the same
  89          * actual pte location.  Fill in each as we go and backtrack on error.
  90          * We need all of these so the DTLB pgtable walk code can find the
  91          * right higher-level entry without knowing if it's a hugepage or not.
  92          */
  93         for (i = 0; i < num_hugepd; i++, hpdp++) {
  94                 if (unlikely(!hugepd_none(*hpdp)))
  95                         break;
  96                 else {
  97 #ifdef CONFIG_PPC_BOOK3S_64
  98                         *hpdp = __hugepd(__pa(new) |
  99                                          (shift_to_mmu_psize(pshift) << 2));
 100 #elif defined(CONFIG_PPC_8xx)
 101                         *hpdp = __hugepd(__pa(new) | _PMD_USER |
 102                                          (pshift == PAGE_SHIFT_8M ? _PMD_PAGE_8M :
 103                                           _PMD_PAGE_512K) | _PMD_PRESENT);
 104 #else
 105                         /* We use the old format for PPC_FSL_BOOK3E */
 106                         *hpdp = __hugepd(((unsigned long)new & ~PD_HUGE) | pshift);
 107 #endif
 108                 }
 109         }
 110         /* If we bailed from the for loop early, an error occurred, clean up */
 111         if (i < num_hugepd) {
 112                 for (i = i - 1 ; i >= 0; i--, hpdp--)
 113                         *hpdp = __hugepd(0);
 114                 kmem_cache_free(cachep, new);
 115         }
 116         spin_unlock(ptl);
 117         return 0;
 118 }
 119
 120 /*
 121  * At this point we do the placement change only for BOOK3S 64. This would
 122  * possibly work on other subarchs.
 123  */
 124 pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz)
 125 {
 126         pgd_t *pg;
 127         pud_t *pu;
 128         pmd_t *pm;
 129         hugepd_t *hpdp = NULL;
 130         unsigned pshift = __ffs(sz);
 131         unsigned pdshift = PGDIR_SHIFT;
 132         spinlock_t *ptl;
 133
 134         addr &= ~(sz-1);
 135         pg = pgd_offset(mm, addr);
 136
 137 #ifdef CONFIG_PPC_BOOK3S_64
 138         if (pshift == PGDIR_SHIFT)
 139                 /* 16GB huge page */
 140                 return (pte_t *) pg;
 141         else if (pshift > PUD_SHIFT) {
 142                 /*
 143                  * We need to use hugepd table
 144                  */
 145                 ptl = &mm->page_table_lock;
 146                 hpdp = (hugepd_t *)pg;
 147         } else {
 148                 pdshift = PUD_SHIFT;
 149                 pu = pud_alloc(mm, pg, addr);
 150                 if (pshift == PUD_SHIFT)
 151                         return (pte_t *)pu;
 152                 else if (pshift > PMD_SHIFT) {
 153                         ptl = pud_lockptr(mm, pu);
 154                         hpdp = (hugepd_t *)pu;
 155                 } else {
 156                         pdshift = PMD_SHIFT;
 157                         pm = pmd_alloc(mm, pu, addr);
 158                         if (pshift == PMD_SHIFT)
 159                                 /* 16MB hugepage */
 160                                 return (pte_t *)pm;
 161                         else {
 162                                 ptl = pmd_lockptr(mm, pm);
 163                                 hpdp = (hugepd_t *)pm;
 164                         }
 165                 }
 166         }
 167 #else
 168         if (pshift >= PGDIR_SHIFT) {
 169                 ptl = &mm->page_table_lock;
 170                 hpdp = (hugepd_t *)pg;
 171         } else {
 172                 pdshift = PUD_SHIFT;
 173                 pu = pud_alloc(mm, pg, addr);
 174                 if (pshift >= PUD_SHIFT) {
 175                         ptl = pud_lockptr(mm, pu);
 176                         hpdp = (hugepd_t *)pu;
 177                 } else {
 178                         pdshift = PMD_SHIFT;
 179                         pm = pmd_alloc(mm, pu, addr);
 180                         ptl = pmd_lockptr(mm, pm);
 181                         hpdp = (hugepd_t *)pm;
 182                 }
 183         }
 184 #endif
 185         if (!hpdp)
 186                 return NULL;
 187
 188         BUG_ON(!hugepd_none(*hpdp) && !hugepd_ok(*hpdp));
 189
 190         if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr,
 191                                                   pdshift, pshift, ptl))
 192                 return NULL;
 193
 194         return hugepte_offset(*hpdp, addr, pdshift);
 195 }
 196
 197 #ifdef CONFIG_PPC_BOOK3S_64
 198 /*
 199  * Tracks gpages after the device tree is scanned and before the
 200  * huge_boot_pages list is ready on pseries.
 201  */
 202 #define MAX_NUMBER_GPAGES       1024
 203 __initdata static u64 gpage_freearray[MAX_NUMBER_GPAGES];
 204 __initdata static unsigned nr_gpages;
 205
 206 /*
 207  * Build list of addresses of gigantic pages.  This function is used in early
 208  * boot before the buddy allocator is setup.
 209  */
 210 void __init pseries_add_gpage(u64 addr, u64 page_size, unsigned long number_of_pages)
 211 {
 212         if (!addr)
 213                 return;
 214         while (number_of_pages > 0) {
 215                 gpage_freearray[nr_gpages] = addr;
 216                 nr_gpages++;
 217                 number_of_pages--;
 218                 addr += page_size;
 219         }
 220 }
 221
 222 int __init pseries_alloc_bootmem_huge_page(struct hstate *hstate)
 223 {
 224         struct huge_bootmem_page *m;
 225         if (nr_gpages == 0)
 226                 return 0;
 227         m = phys_to_virt(gpage_freearray[--nr_gpages]);
 228         gpage_freearray[nr_gpages] = 0;
 229         list_add(&m->list, &huge_boot_pages);
 230         m->hstate = hstate;
 231         return 1;
 232 }
 233 #endif
 234
 235
 236 int __init alloc_bootmem_huge_page(struct hstate *h)
 237 {
 238
 239 #ifdef CONFIG_PPC_BOOK3S_64
 240         if (firmware_has_feature(FW_FEATURE_LPAR) && !radix_enabled())
 241                 return pseries_alloc_bootmem_huge_page(h);
 242 #endif
 243         return __alloc_bootmem_huge_page(h);
 244 }
 245
 246 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 247 #define HUGEPD_FREELIST_SIZE \
 248         ((PAGE_SIZE - sizeof(struct hugepd_freelist)) / sizeof(pte_t))
 249
 250 struct hugepd_freelist {
 251         struct rcu_head rcu;
 252         unsigned int index;
 253         void *ptes[0];
 254 };
 255
 256 static DEFINE_PER_CPU(struct hugepd_freelist *, hugepd_freelist_cur);
 257
 258 static void hugepd_free_rcu_callback(struct rcu_head *head)
 259 {
 260         struct hugepd_freelist *batch =
 261                 container_of(head, struct hugepd_freelist, rcu);
 262         unsigned int i;
 263
 264         for (i = 0; i < batch->index; i++)
 265                 kmem_cache_free(hugepte_cache, batch->ptes[i]);
 266
 267         free_page((unsigned long)batch);
 268 }
 269
 270 static void hugepd_free(struct mmu_gather *tlb, void *hugepte)
 271 {
 272         struct hugepd_freelist **batchp;
 273
 274         batchp = &get_cpu_var(hugepd_freelist_cur);
 275
 276         if (atomic_read(&tlb->mm->mm_users) < 2 ||
 277             mm_is_thread_local(tlb->mm)) {
 278                 kmem_cache_free(hugepte_cache, hugepte);
 279                 put_cpu_var(hugepd_freelist_cur);
 280                 return;
 281         }
 282
 283         if (*batchp == NULL) {
 284                 *batchp = (struct hugepd_freelist *)__get_free_page(GFP_ATOMIC);
 285                 (*batchp)->index = 0;
 286         }
 287
 288         (*batchp)->ptes[(*batchp)->index++] = hugepte;
 289         if ((*batchp)->index == HUGEPD_FREELIST_SIZE) {
 290                 call_rcu_sched(&(*batchp)->rcu, hugepd_free_rcu_callback);
 291                 *batchp = NULL;
 292         }
 293         put_cpu_var(hugepd_freelist_cur);
 294 }
 295 #else
 296 static inline void hugepd_free(struct mmu_gather *tlb, void *hugepte) {}
 297 #endif
 298
 299 static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshift,
 300                               unsigned long start, unsigned long end,
 301                               unsigned long floor, unsigned long ceiling)
 302 {
 303         pte_t *hugepte = hugepd_page(*hpdp);
 304         int i;
 305
 306         unsigned long pdmask = ~((1UL << pdshift) - 1);
 307         unsigned int num_hugepd = 1;
 308         unsigned int shift = hugepd_shift(*hpdp);
 309
 310         /* Note: On fsl the hpdp may be the first of several */
 311         if (shift > pdshift)
 312                 num_hugepd = 1 << (shift - pdshift);
 313
 314         start &= pdmask;
 315         if (start < floor)
 316                 return;
 317         if (ceiling) {
 318                 ceiling &= pdmask;
 319                 if (! ceiling)
 320                         return;
 321         }
 322         if (end - 1 > ceiling - 1)
 323                 return;
 324
 325         for (i = 0; i < num_hugepd; i++, hpdp++)
 326                 *hpdp = __hugepd(0);
 327
 328         if (shift >= pdshift)
 329                 hugepd_free(tlb, hugepte);
 330         else
 331                 pgtable_free_tlb(tlb, hugepte,
 332                                  get_hugepd_cache_index(pdshift - shift));
 333 }
 334
 335 static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
 336                                    unsigned long addr, unsigned long end,
 337                                    unsigned long floor, unsigned long ceiling)
 338 {
 339         pmd_t *pmd;
 340         unsigned long next;
 341         unsigned long start;
 342
 343         start = addr;
 344         do {
 345                 unsigned long more;
 346
 347                 pmd = pmd_offset(pud, addr);
 348                 next = pmd_addr_end(addr, end);
 349                 if (!is_hugepd(__hugepd(pmd_val(*pmd)))) {
 350                         /*
 351                          * if it is not hugepd pointer, we should already find
 352                          * it cleared.
 353                          */
 354                         WARN_ON(!pmd_none_or_clear_bad(pmd));
 355                         continue;
 356                 }
 357                 /*
 358                  * Increment next by the size of the huge mapping since
 359                  * there may be more than one entry at this level for a
 360                  * single hugepage, but all of them point to
 361                  * the same kmem cache that holds the hugepte.
 362                  */
 363                 more = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
 364                 if (more > next)
 365                         next = more;
 366
 367                 free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
 368                                   addr, next, floor, ceiling);
 369         } while (addr = next, addr != end);
 370
 371         start &= PUD_MASK;
 372         if (start < floor)
 373                 return;
 374         if (ceiling) {
 375                 ceiling &= PUD_MASK;
 376                 if (!ceiling)
 377                         return;
 378         }
 379         if (end - 1 > ceiling - 1)
 380                 return;
 381
 382         pmd = pmd_offset(pud, start);
 383         pud_clear(pud);
 384         pmd_free_tlb(tlb, pmd, start);
 385         mm_dec_nr_pmds(tlb->mm);
 386 }
 387
 388 static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
 389                                    unsigned long addr, unsigned long end,
 390                                    unsigned long floor, unsigned long ceiling)
 391 {
 392         pud_t *pud;
 393         unsigned long next;
 394         unsigned long start;
 395
 396         start = addr;
 397         do {
 398                 pud = pud_offset(pgd, addr);
 399                 next = pud_addr_end(addr, end);
 400                 if (!is_hugepd(__hugepd(pud_val(*pud)))) {
 401                         if (pud_none_or_clear_bad(pud))
 402                                 continue;
 403                         hugetlb_free_pmd_range(tlb, pud, addr, next, floor,
 404                                                ceiling);
 405                 } else {
 406                         unsigned long more;
 407                         /*
 408                          * Increment next by the size of the huge mapping since
 409                          * there may be more than one entry at this level for a
 410                          * single hugepage, but all of them point to
 411                          * the same kmem cache that holds the hugepte.
 412                          */
 413                         more = addr + (1 << hugepd_shift(*(hugepd_t *)pud));
 414                         if (more > next)
 415                                 next = more;
 416
 417                         free_hugepd_range(tlb, (hugepd_t *)pud, PUD_SHIFT,
 418                                           addr, next, floor, ceiling);
 419                 }
 420         } while (addr = next, addr != end);
 421
 422         start &= PGDIR_MASK;
 423         if (start < floor)
 424                 return;
 425         if (ceiling) {
 426                 ceiling &= PGDIR_MASK;
 427                 if (!ceiling)
 428                         return;
 429         }
 430         if (end - 1 > ceiling - 1)
 431                 return;
 432
 433         pud = pud_offset(pgd, start);
 434         pgd_clear(pgd);
 435         pud_free_tlb(tlb, pud, start);
 436         mm_dec_nr_puds(tlb->mm);
 437 }
 438
 439 /*
 440  * This function frees user-level page tables of a process.
 441  */
 442 void hugetlb_free_pgd_range(struct mmu_gather *tlb,
 443                             unsigned long addr, unsigned long end,
 444                             unsigned long floor, unsigned long ceiling)
 445 {
 446         pgd_t *pgd;
 447         unsigned long next;
 448
 449         /*
 450          * Because there are a number of different possible pagetable
 451          * layouts for hugepage ranges, we limit knowledge of how
 452          * things should be laid out to the allocation path
 453          * (huge_pte_alloc(), above).  Everything else works out the
 454          * structure as it goes from information in the hugepd
 455          * pointers.  That means that we can't here use the
 456          * optimization used in the normal page free_pgd_range(), of
 457          * checking whether we're actually covering a large enough
 458          * range to have to do anything at the top level of the walk
 459          * instead of at the bottom.
 460          *
 461          * To make sense of this, you should probably go read the big
 462          * block comment at the top of the normal free_pgd_range(),
 463          * too.
 464          */
 465
 466         do {
 467                 next = pgd_addr_end(addr, end);
 468                 pgd = pgd_offset(tlb->mm, addr);
 469                 if (!is_hugepd(__hugepd(pgd_val(*pgd)))) {
 470                         if (pgd_none_or_clear_bad(pgd))
 471                                 continue;
 472                         hugetlb_free_pud_range(tlb, pgd, addr, next, floor, ceiling);
 473                 } else {
 474                         unsigned long more;
 475                         /*
 476                          * Increment next by the size of the huge mapping since
 477                          * there may be more than one entry at the pgd level
 478                          * for a single hugepage, but all of them point to the
 479                          * same kmem cache that holds the hugepte.
 480                          */
 481                         more = addr + (1 << hugepd_shift(*(hugepd_t *)pgd));
 482                         if (more > next)
 483                                 next = more;
 484
 485                         free_hugepd_range(tlb, (hugepd_t *)pgd, PGDIR_SHIFT,
 486                                           addr, next, floor, ceiling);
 487                 }
 488         } while (addr = next, addr != end);
 489 }
 490
 491 struct page *follow_huge_pd(struct vm_area_struct *vma,
 492                             unsigned long address, hugepd_t hpd,
 493                             int flags, int pdshift)
 494 {
 495         pte_t *ptep;
 496         spinlock_t *ptl;
 497         struct page *page = NULL;
 498         unsigned long mask;
 499         int shift = hugepd_shift(hpd);
 500         struct mm_struct *mm = vma->vm_mm;
 501
 502 retry:
 503         /*
 504          * hugepage directory entries are protected by mm->page_table_lock
 505          * Use this instead of huge_pte_lockptr
 506          */
 507         ptl = &mm->page_table_lock;
 508         spin_lock(ptl);
 509
 510         ptep = hugepte_offset(hpd, address, pdshift);
 511         if (pte_present(*ptep)) {
 512                 mask = (1UL << shift) - 1;
 513                 page = pte_page(*ptep);
 514                 page += ((address & mask) >> PAGE_SHIFT);
 515                 if (flags & FOLL_GET)
 516                         get_page(page);
 517         } else {
 518                 if (is_hugetlb_entry_migration(*ptep)) {
 519                         spin_unlock(ptl);
 520                         __migration_entry_wait(mm, ptep, ptl);
 521                         goto retry;
 522                 }
 523         }
 524         spin_unlock(ptl);
 525         return page;
 526 }
 527
 528 static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
 529                                       unsigned long sz)
 530 {
 531         unsigned long __boundary = (addr + sz) & ~(sz-1);
 532         return (__boundary - 1 < end - 1) ? __boundary : end;
 533 }
 534
 535 int gup_huge_pd(hugepd_t hugepd, unsigned long addr, unsigned pdshift,
 536                 unsigned long end, int write, struct page **pages, int *nr)
 537 {
 538         pte_t *ptep;
 539         unsigned long sz = 1UL << hugepd_shift(hugepd);
 540         unsigned long next;
 541
 542         ptep = hugepte_offset(hugepd, addr, pdshift);
 543         do {
 544                 next = hugepte_addr_end(addr, end, sz);
 545                 if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
 546                         return 0;
 547         } while (ptep++, addr = next, addr != end);
 548
 549         return 1;
 550 }
 551
 552 #ifdef CONFIG_PPC_MM_SLICES
 553 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 554                                         unsigned long len, unsigned long pgoff,
 555                                         unsigned long flags)
 556 {
 557         struct hstate *hstate = hstate_file(file);
 558         int mmu_psize = shift_to_mmu_psize(huge_page_shift(hstate));
 559
 560 #ifdef CONFIG_PPC_RADIX_MMU
 561         if (radix_enabled())
 562                 return radix__hugetlb_get_unmapped_area(file, addr, len,
 563                                                        pgoff, flags);
 564 #endif
 565         return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1);
 566 }
 567 #endif
 568
 569 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
 570 {
 571 #ifdef CONFIG_PPC_MM_SLICES
 572         /* With radix we don't use slice, so derive it from vma*/
 573         if (!radix_enabled()) {
 574                 unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);
 575
 576                 return 1UL << mmu_psize_to_shift(psize);
 577         }
 578 #endif
 579         return vma_kernel_pagesize(vma);
 580 }
 581
 582 static inline bool is_power_of_4(unsigned long x)
 583 {
 584         if (is_power_of_2(x))
 585                 return (__ilog2(x) % 2) ? false : true;
 586         return false;
 587 }
 588
 589 static int __init add_huge_page_size(unsigned long long size)
 590 {
 591         int shift = __ffs(size);
 592         int mmu_psize;
 593
 594         /* Check that it is a page size supported by the hardware and
 595          * that it fits within pagetable and slice limits. */
 596         if (size <= PAGE_SIZE)
 597                 return -EINVAL;
 598 #if defined(CONFIG_PPC_FSL_BOOK3E)
 599         if (!is_power_of_4(size))
 600                 return -EINVAL;
 601 #elif !defined(CONFIG_PPC_8xx)
 602         if (!is_power_of_2(size) || (shift > SLICE_HIGH_SHIFT))
 603                 return -EINVAL;
 604 #endif
 605
 606         if ((mmu_psize = shift_to_mmu_psize(shift)) < 0)
 607                 return -EINVAL;
 608
 609 #ifdef CONFIG_PPC_BOOK3S_64
 610         /*
 611          * We need to make sure that for different page sizes reported by
 612          * firmware we only add hugetlb support for page sizes that can be
 613          * supported by linux page table layout.
 614          * For now we have
 615          * Radix: 2M and 1G
 616          * Hash: 16M and 16G
 617          */
 618         if (radix_enabled()) {
 619                 if (mmu_psize != MMU_PAGE_2M && mmu_psize != MMU_PAGE_1G)
 620                         return -EINVAL;
 621         } else {
 622                 if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G)
 623                         return -EINVAL;
 624         }
 625 #endif
 626
 627         BUG_ON(mmu_psize_defs[mmu_psize].shift != shift);
 628
 629         /* Return if huge page size has already been setup */
 630         if (size_to_hstate(size))
 631                 return 0;
 632
 633         hugetlb_add_hstate(shift - PAGE_SHIFT);
 634
 635         return 0;
 636 }
 637
 638 static int __init hugepage_setup_sz(char *str)
 639 {
 640         unsigned long long size;
 641
 642         size = memparse(str, &str);
 643
 644         if (add_huge_page_size(size) != 0) {
 645                 hugetlb_bad_size();
 646                 pr_err("Invalid huge page size specified(%llu)\n", size);
 647         }
 648
 649         return 1;
 650 }
 651 __setup("hugepagesz=", hugepage_setup_sz);
 652
 653 struct kmem_cache *hugepte_cache;
 654 static int __init hugetlbpage_init(void)
 655 {
 656         int psize;
 657
 658         if (hugetlb_disabled) {
 659                 pr_info("HugeTLB support is disabled!\n");
 660                 return 0;
 661         }
 662
 663 #if !defined(CONFIG_PPC_FSL_BOOK3E) && !defined(CONFIG_PPC_8xx)
 664         if (!radix_enabled() && !mmu_has_feature(MMU_FTR_16M_PAGE))
 665                 return -ENODEV;
 666 #endif
 667         for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
 668                 unsigned shift;
 669                 unsigned pdshift;
 670
 671                 if (!mmu_psize_defs[psize].shift)
 672                         continue;
 673
 674                 shift = mmu_psize_to_shift(psize);
 675
 676 #ifdef CONFIG_PPC_BOOK3S_64
 677                 if (shift > PGDIR_SHIFT)
 678                         continue;
 679                 else if (shift > PUD_SHIFT)
 680                         pdshift = PGDIR_SHIFT;
 681                 else if (shift > PMD_SHIFT)
 682                         pdshift = PUD_SHIFT;
 683                 else
 684                         pdshift = PMD_SHIFT;
 685 #else
 686                 if (shift < PUD_SHIFT)
 687                         pdshift = PMD_SHIFT;
 688                 else if (shift < PGDIR_SHIFT)
 689                         pdshift = PUD_SHIFT;
 690                 else
 691                         pdshift = PGDIR_SHIFT;
 692 #endif
 693
 694                 if (add_huge_page_size(1ULL << shift) < 0)
 695                         continue;
 696                 /*
 697                  * if we have pdshift and shift value same, we don't
 698                  * use pgt cache for hugepd.
 699                  */
 700                 if (pdshift > shift)
 701                         pgtable_cache_add(pdshift - shift, NULL);
 702 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 703                 else if (!hugepte_cache) {
 704                         /*
 705                          * Create a kmem cache for hugeptes.  The bottom bits in
 706                          * the pte have size information encoded in them, so
 707                          * align them to allow this
 708                          */
 709                         hugepte_cache = kmem_cache_create("hugepte-cache",
 710                                                           sizeof(pte_t),
 711                                                           HUGEPD_SHIFT_MASK + 1,
 712                                                           0, NULL);
 713                         if (hugepte_cache == NULL)
 714                                 panic("%s: Unable to create kmem cache "
 715                                       "for hugeptes\n", __func__);
 716
 717                 }
 718 #endif
 719         }
 720
 721 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 722         /* Default hpage size = 4M on FSL_BOOK3E and 512k on 8xx */
 723         if (mmu_psize_defs[MMU_PAGE_4M].shift)
 724                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_4M].shift;
 725         else if (mmu_psize_defs[MMU_PAGE_512K].shift)
 726                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_512K].shift;
 727 #else
 728         /* Set default large page size. Currently, we pick 16M or 1M
 729          * depending on what is available
 730          */
 731         if (mmu_psize_defs[MMU_PAGE_16M].shift)
 732                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_16M].shift;
 733         else if (mmu_psize_defs[MMU_PAGE_1M].shift)
 734                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_1M].shift;
 735         else if (mmu_psize_defs[MMU_PAGE_2M].shift)
 736                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_2M].shift;
 737 #endif
 738         return 0;
 739 }
 740
 741 arch_initcall(hugetlbpage_init);
 742
 743 void flush_dcache_icache_hugepage(struct page *page)
 744 {
 745         int i;
 746         void *start;
 747
 748         BUG_ON(!PageCompound(page));
 749
 750         for (i = 0; i < (1UL << compound_order(page)); i++) {
 751                 if (!PageHighMem(page)) {
 752                         __flush_dcache_icache(page_address(page+i));
 753                 } else {
 754                         start = kmap_atomic(page+i);
 755                         __flush_dcache_icache(start);
 756                         kunmap_atomic(start);
 757                 }
 758         }
 759 }
 760
 761 #endif /* CONFIG_HUGETLB_PAGE */
 762
 763 /*
 764  * We have 4 cases for pgds and pmds:
 765  * (1) invalid (all zeroes)
 766  * (2) pointer to next table, as normal; bottom 6 bits == 0
 767  * (3) leaf pte for huge page _PAGE_PTE set
 768  * (4) hugepd pointer, _PAGE_PTE = 0 and bits [2..6] indicate size of table
 769  *
 770  * So long as we atomically load page table pointers we are safe against teardown,
 771  * we can follow the address down to the the page and take a ref on it.
 772  * This function need to be called with interrupts disabled. We use this variant
 773  * when we have MSR[EE] = 0 but the paca->irq_soft_mask = IRQS_ENABLED
 774  */
 775 pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
 776                         bool *is_thp, unsigned *hpage_shift)
 777 {
 778         pgd_t pgd, *pgdp;
 779         pud_t pud, *pudp;
 780         pmd_t pmd, *pmdp;
 781         pte_t *ret_pte;
 782         hugepd_t *hpdp = NULL;
 783         unsigned pdshift = PGDIR_SHIFT;
 784
 785         if (hpage_shift)
 786                 *hpage_shift = 0;
 787
 788         if (is_thp)
 789                 *is_thp = false;
 790
 791         pgdp = pgdir + pgd_index(ea);
 792         pgd  = READ_ONCE(*pgdp);
 793         /*
 794          * Always operate on the local stack value. This make sure the
 795          * value don't get updated by a parallel THP split/collapse,
 796          * page fault or a page unmap. The return pte_t * is still not
 797          * stable. So should be checked there for above conditions.
 798          */
 799         if (pgd_none(pgd))
 800                 return NULL;
 801         else if (pgd_huge(pgd)) {
 802                 ret_pte = (pte_t *) pgdp;
 803                 goto out;
 804         } else if (is_hugepd(__hugepd(pgd_val(pgd))))
 805                 hpdp = (hugepd_t *)&pgd;
 806         else {
 807                 /*
 808                  * Even if we end up with an unmap, the pgtable will not
 809                  * be freed, because we do an rcu free and here we are
 810                  * irq disabled
 811                  */
 812                 pdshift = PUD_SHIFT;
 813                 pudp = pud_offset(&pgd, ea);
 814                 pud  = READ_ONCE(*pudp);
 815
 816                 if (pud_none(pud))
 817                         return NULL;
 818                 else if (pud_huge(pud)) {
 819                         ret_pte = (pte_t *) pudp;
 820                         goto out;
 821                 } else if (is_hugepd(__hugepd(pud_val(pud))))
 822                         hpdp = (hugepd_t *)&pud;
 823                 else {
 824                         pdshift = PMD_SHIFT;
 825                         pmdp = pmd_offset(&pud, ea);
 826                         pmd  = READ_ONCE(*pmdp);
 827                         /*
 828                          * A hugepage collapse is captured by pmd_none, because
 829                          * it mark the pmd none and do a hpte invalidate.
 830                          */
 831                         if (pmd_none(pmd))
 832                                 return NULL;
 833
 834                         if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
 835                                 if (is_thp)
 836                                         *is_thp = true;
 837                                 ret_pte = (pte_t *) pmdp;
 838                                 goto out;
 839                         }
 840
 841                         if (pmd_huge(pmd)) {
 842                                 ret_pte = (pte_t *) pmdp;
 843                                 goto out;
 844                         } else if (is_hugepd(__hugepd(pmd_val(pmd))))
 845                                 hpdp = (hugepd_t *)&pmd;
 846                         else
 847                                 return pte_offset_kernel(&pmd, ea);
 848                 }
 849         }
 850         if (!hpdp)
 851                 return NULL;
 852
 853         ret_pte = hugepte_offset(*hpdp, ea, pdshift);
 854         pdshift = hugepd_shift(*hpdp);
 855 out:
 856         if (hpage_shift)
 857                 *hpage_shift = pdshift;
 858         return ret_pte;
 859 }
 860 EXPORT_SYMBOL_GPL(__find_linux_pte);
 861
 862 int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 863                 unsigned long end, int write, struct page **pages, int *nr)
 864 {
 865         unsigned long pte_end;
 866         struct page *head, *page;
 867         pte_t pte;
 868         int refs;
 869
 870         pte_end = (addr + sz) & ~(sz-1);
 871         if (pte_end < end)
 872                 end = pte_end;
 873
 874         pte = READ_ONCE(*ptep);
 875
 876         if (!pte_access_permitted(pte, write))
 877                 return 0;
 878
 879         /* hugepages are never "special" */
 880         VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
 881
 882         refs = 0;
 883         head = pte_page(pte);
 884
 885         page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
 886         do {
 887                 VM_BUG_ON(compound_head(page) != head);
 888                 pages[*nr] = page;
 889                 (*nr)++;
 890                 page++;
 891                 refs++;
 892         } while (addr += PAGE_SIZE, addr != end);
 893
 894         if (!page_cache_add_speculative(head, refs)) {
 895                 *nr -= refs;
 896                 return 0;
 897         }
 898
 899         if (unlikely(pte_val(pte) != pte_val(*ptep))) {
 900                 /* Could be optimized better */
 901                 *nr -= refs;
 902                 while (refs--)
 903                         put_page(head);
 904                 return 0;
 905         }
 906
 907         return 1;
 908 }