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 <linux/kmemleak.h>
  23 #include <asm/pgtable.h>
  24 #include <asm/pgalloc.h>
  25 #include <asm/tlb.h>
  26 #include <asm/setup.h>
  27 #include <asm/hugetlb.h>
  28 #include <asm/pte-walk.h>
  29
  30
  31 #ifdef CONFIG_HUGETLB_PAGE
  32
  33 #define PAGE_SHIFT_64K  16
  34 #define PAGE_SHIFT_512K 19
  35 #define PAGE_SHIFT_8M   23
  36 #define PAGE_SHIFT_16M  24
  37 #define PAGE_SHIFT_16G  34
  38
  39 bool hugetlb_disabled = false;
  40
  41 unsigned int HPAGE_SHIFT;
  42 EXPORT_SYMBOL(HPAGE_SHIFT);
  43
  44 #define hugepd_none(hpd)        (hpd_val(hpd) == 0)
  45
  46 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long sz)
  47 {
  48         /*
  49          * Only called for hugetlbfs pages, hence can ignore THP and the
  50          * irq disabled walk.
  51          */
  52         return __find_linux_pte(mm->pgd, addr, NULL, NULL);
  53 }
  54
  55 static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
  56                            unsigned long address, unsigned int pdshift,
  57                            unsigned int pshift, spinlock_t *ptl)
  58 {
  59         struct kmem_cache *cachep;
  60         pte_t *new;
  61         int i;
  62         int num_hugepd;
  63
  64         if (pshift >= pdshift) {
  65                 cachep = hugepte_cache;
  66                 num_hugepd = 1 << (pshift - pdshift);
  67         } else {
  68                 cachep = PGT_CACHE(pdshift - pshift);
  69                 num_hugepd = 1;
  70         }
  71
  72         new = kmem_cache_zalloc(cachep, pgtable_gfp_flags(mm, GFP_KERNEL));
  73
  74         BUG_ON(pshift > HUGEPD_SHIFT_MASK);
  75         BUG_ON((unsigned long)new & HUGEPD_SHIFT_MASK);
  76
  77         if (! new)
  78                 return -ENOMEM;
  79
  80         /*
  81          * Make sure other cpus find the hugepd set only after a
  82          * properly initialized page table is visible to them.
  83          * For more details look for comment in __pte_alloc().
  84          */
  85         smp_wmb();
  86
  87         spin_lock(ptl);
  88         /*
  89          * We have multiple higher-level entries that point to the same
  90          * actual pte location.  Fill in each as we go and backtrack on error.
  91          * We need all of these so the DTLB pgtable walk code can find the
  92          * right higher-level entry without knowing if it's a hugepage or not.
  93          */
  94         for (i = 0; i < num_hugepd; i++, hpdp++) {
  95                 if (unlikely(!hugepd_none(*hpdp)))
  96                         break;
  97                 else {
  98 #ifdef CONFIG_PPC_BOOK3S_64
  99                         *hpdp = __hugepd(__pa(new) |
 100                                          (shift_to_mmu_psize(pshift) << 2));
 101 #elif defined(CONFIG_PPC_8xx)
 102                         *hpdp = __hugepd(__pa(new) | _PMD_USER |
 103                                          (pshift == PAGE_SHIFT_8M ? _PMD_PAGE_8M :
 104                                           _PMD_PAGE_512K) | _PMD_PRESENT);
 105 #else
 106                         /* We use the old format for PPC_FSL_BOOK3E */
 107                         *hpdp = __hugepd(((unsigned long)new & ~PD_HUGE) | pshift);
 108 #endif
 109                 }
 110         }
 111         /* If we bailed from the for loop early, an error occurred, clean up */
 112         if (i < num_hugepd) {
 113                 for (i = i - 1 ; i >= 0; i--, hpdp--)
 114                         *hpdp = __hugepd(0);
 115                 kmem_cache_free(cachep, new);
 116         } else {
 117                 kmemleak_ignore(new);
 118         }
 119         spin_unlock(ptl);
 120         return 0;
 121 }
 122
 123 /*
 124  * At this point we do the placement change only for BOOK3S 64. This would
 125  * possibly work on other subarchs.
 126  */
 127 pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz)
 128 {
 129         pgd_t *pg;
 130         pud_t *pu;
 131         pmd_t *pm;
 132         hugepd_t *hpdp = NULL;
 133         unsigned pshift = __ffs(sz);
 134         unsigned pdshift = PGDIR_SHIFT;
 135         spinlock_t *ptl;
 136
 137         addr &= ~(sz-1);
 138         pg = pgd_offset(mm, addr);
 139
 140 #ifdef CONFIG_PPC_BOOK3S_64
 141         if (pshift == PGDIR_SHIFT)
 142                 /* 16GB huge page */
 143                 return (pte_t *) pg;
 144         else if (pshift > PUD_SHIFT) {
 145                 /*
 146                  * We need to use hugepd table
 147                  */
 148                 ptl = &mm->page_table_lock;
 149                 hpdp = (hugepd_t *)pg;
 150         } else {
 151                 pdshift = PUD_SHIFT;
 152                 pu = pud_alloc(mm, pg, addr);
 153                 if (!pu)
 154                         return NULL;
 155                 if (pshift == PUD_SHIFT)
 156                         return (pte_t *)pu;
 157                 else if (pshift > PMD_SHIFT) {
 158                         ptl = pud_lockptr(mm, pu);
 159                         hpdp = (hugepd_t *)pu;
 160                 } else {
 161                         pdshift = PMD_SHIFT;
 162                         pm = pmd_alloc(mm, pu, addr);
 163                         if (!pm)
 164                                 return NULL;
 165                         if (pshift == PMD_SHIFT)
 166                                 /* 16MB hugepage */
 167                                 return (pte_t *)pm;
 168                         else {
 169                                 ptl = pmd_lockptr(mm, pm);
 170                                 hpdp = (hugepd_t *)pm;
 171                         }
 172                 }
 173         }
 174 #else
 175         if (pshift >= PGDIR_SHIFT) {
 176                 ptl = &mm->page_table_lock;
 177                 hpdp = (hugepd_t *)pg;
 178         } else {
 179                 pdshift = PUD_SHIFT;
 180                 pu = pud_alloc(mm, pg, addr);
 181                 if (!pu)
 182                         return NULL;
 183                 if (pshift >= PUD_SHIFT) {
 184                         ptl = pud_lockptr(mm, pu);
 185                         hpdp = (hugepd_t *)pu;
 186                 } else {
 187                         pdshift = PMD_SHIFT;
 188                         pm = pmd_alloc(mm, pu, addr);
 189                         if (!pm)
 190                                 return NULL;
 191                         ptl = pmd_lockptr(mm, pm);
 192                         hpdp = (hugepd_t *)pm;
 193                 }
 194         }
 195 #endif
 196         if (!hpdp)
 197                 return NULL;
 198
 199         BUG_ON(!hugepd_none(*hpdp) && !hugepd_ok(*hpdp));
 200
 201         if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr,
 202                                                   pdshift, pshift, ptl))
 203                 return NULL;
 204
 205         return hugepte_offset(*hpdp, addr, pdshift);
 206 }
 207
 208 #ifdef CONFIG_PPC_BOOK3S_64
 209 /*
 210  * Tracks gpages after the device tree is scanned and before the
 211  * huge_boot_pages list is ready on pseries.
 212  */
 213 #define MAX_NUMBER_GPAGES       1024
 214 __initdata static u64 gpage_freearray[MAX_NUMBER_GPAGES];
 215 __initdata static unsigned nr_gpages;
 216
 217 /*
 218  * Build list of addresses of gigantic pages.  This function is used in early
 219  * boot before the buddy allocator is setup.
 220  */
 221 void __init pseries_add_gpage(u64 addr, u64 page_size, unsigned long number_of_pages)
 222 {
 223         if (!addr)
 224                 return;
 225         while (number_of_pages > 0) {
 226                 gpage_freearray[nr_gpages] = addr;
 227                 nr_gpages++;
 228                 number_of_pages--;
 229                 addr += page_size;
 230         }
 231 }
 232
 233 int __init pseries_alloc_bootmem_huge_page(struct hstate *hstate)
 234 {
 235         struct huge_bootmem_page *m;
 236         if (nr_gpages == 0)
 237                 return 0;
 238         m = phys_to_virt(gpage_freearray[--nr_gpages]);
 239         gpage_freearray[nr_gpages] = 0;
 240         list_add(&m->list, &huge_boot_pages);
 241         m->hstate = hstate;
 242         return 1;
 243 }
 244 #endif
 245
 246
 247 int __init alloc_bootmem_huge_page(struct hstate *h)
 248 {
 249
 250 #ifdef CONFIG_PPC_BOOK3S_64
 251         if (firmware_has_feature(FW_FEATURE_LPAR) && !radix_enabled())
 252                 return pseries_alloc_bootmem_huge_page(h);
 253 #endif
 254         return __alloc_bootmem_huge_page(h);
 255 }
 256
 257 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 258 #define HUGEPD_FREELIST_SIZE \
 259         ((PAGE_SIZE - sizeof(struct hugepd_freelist)) / sizeof(pte_t))
 260
 261 struct hugepd_freelist {
 262         struct rcu_head rcu;
 263         unsigned int index;
 264         void *ptes[0];
 265 };
 266
 267 static DEFINE_PER_CPU(struct hugepd_freelist *, hugepd_freelist_cur);
 268
 269 static void hugepd_free_rcu_callback(struct rcu_head *head)
 270 {
 271         struct hugepd_freelist *batch =
 272                 container_of(head, struct hugepd_freelist, rcu);
 273         unsigned int i;
 274
 275         for (i = 0; i < batch->index; i++)
 276                 kmem_cache_free(hugepte_cache, batch->ptes[i]);
 277
 278         free_page((unsigned long)batch);
 279 }
 280
 281 static void hugepd_free(struct mmu_gather *tlb, void *hugepte)
 282 {
 283         struct hugepd_freelist **batchp;
 284
 285         batchp = &get_cpu_var(hugepd_freelist_cur);
 286
 287         if (atomic_read(&tlb->mm->mm_users) < 2 ||
 288             mm_is_thread_local(tlb->mm)) {
 289                 kmem_cache_free(hugepte_cache, hugepte);
 290                 put_cpu_var(hugepd_freelist_cur);
 291                 return;
 292         }
 293
 294         if (*batchp == NULL) {
 295                 *batchp = (struct hugepd_freelist *)__get_free_page(GFP_ATOMIC);
 296                 (*batchp)->index = 0;
 297         }
 298
 299         (*batchp)->ptes[(*batchp)->index++] = hugepte;
 300         if ((*batchp)->index == HUGEPD_FREELIST_SIZE) {
 301                 call_rcu_sched(&(*batchp)->rcu, hugepd_free_rcu_callback);
 302                 *batchp = NULL;
 303         }
 304         put_cpu_var(hugepd_freelist_cur);
 305 }
 306 #else
 307 static inline void hugepd_free(struct mmu_gather *tlb, void *hugepte) {}
 308 #endif
 309
 310 static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshift,
 311                               unsigned long start, unsigned long end,
 312                               unsigned long floor, unsigned long ceiling)
 313 {
 314         pte_t *hugepte = hugepd_page(*hpdp);
 315         int i;
 316
 317         unsigned long pdmask = ~((1UL << pdshift) - 1);
 318         unsigned int num_hugepd = 1;
 319         unsigned int shift = hugepd_shift(*hpdp);
 320
 321         /* Note: On fsl the hpdp may be the first of several */
 322         if (shift > pdshift)
 323                 num_hugepd = 1 << (shift - pdshift);
 324
 325         start &= pdmask;
 326         if (start < floor)
 327                 return;
 328         if (ceiling) {
 329                 ceiling &= pdmask;
 330                 if (! ceiling)
 331                         return;
 332         }
 333         if (end - 1 > ceiling - 1)
 334                 return;
 335
 336         for (i = 0; i < num_hugepd; i++, hpdp++)
 337                 *hpdp = __hugepd(0);
 338
 339         if (shift >= pdshift)
 340                 hugepd_free(tlb, hugepte);
 341         else
 342                 pgtable_free_tlb(tlb, hugepte,
 343                                  get_hugepd_cache_index(pdshift - shift));
 344 }
 345
 346 static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
 347                                    unsigned long addr, unsigned long end,
 348                                    unsigned long floor, unsigned long ceiling)
 349 {
 350         pmd_t *pmd;
 351         unsigned long next;
 352         unsigned long start;
 353
 354         start = addr;
 355         do {
 356                 unsigned long more;
 357
 358                 pmd = pmd_offset(pud, addr);
 359                 next = pmd_addr_end(addr, end);
 360                 if (!is_hugepd(__hugepd(pmd_val(*pmd)))) {
 361                         /*
 362                          * if it is not hugepd pointer, we should already find
 363                          * it cleared.
 364                          */
 365                         WARN_ON(!pmd_none_or_clear_bad(pmd));
 366                         continue;
 367                 }
 368                 /*
 369                  * Increment next by the size of the huge mapping since
 370                  * there may be more than one entry at this level for a
 371                  * single hugepage, but all of them point to
 372                  * the same kmem cache that holds the hugepte.
 373                  */
 374                 more = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
 375                 if (more > next)
 376                         next = more;
 377
 378                 free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
 379                                   addr, next, floor, ceiling);
 380         } while (addr = next, addr != end);
 381
 382         start &= PUD_MASK;
 383         if (start < floor)
 384                 return;
 385         if (ceiling) {
 386                 ceiling &= PUD_MASK;
 387                 if (!ceiling)
 388                         return;
 389         }
 390         if (end - 1 > ceiling - 1)
 391                 return;
 392
 393         pmd = pmd_offset(pud, start);
 394         pud_clear(pud);
 395         pmd_free_tlb(tlb, pmd, start);
 396         mm_dec_nr_pmds(tlb->mm);
 397 }
 398
 399 static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
 400                                    unsigned long addr, unsigned long end,
 401                                    unsigned long floor, unsigned long ceiling)
 402 {
 403         pud_t *pud;
 404         unsigned long next;
 405         unsigned long start;
 406
 407         start = addr;
 408         do {
 409                 pud = pud_offset(pgd, addr);
 410                 next = pud_addr_end(addr, end);
 411                 if (!is_hugepd(__hugepd(pud_val(*pud)))) {
 412                         if (pud_none_or_clear_bad(pud))
 413                                 continue;
 414                         hugetlb_free_pmd_range(tlb, pud, addr, next, floor,
 415                                                ceiling);
 416                 } else {
 417                         unsigned long more;
 418                         /*
 419                          * Increment next by the size of the huge mapping since
 420                          * there may be more than one entry at this level for a
 421                          * single hugepage, but all of them point to
 422                          * the same kmem cache that holds the hugepte.
 423                          */
 424                         more = addr + (1 << hugepd_shift(*(hugepd_t *)pud));
 425                         if (more > next)
 426                                 next = more;
 427
 428                         free_hugepd_range(tlb, (hugepd_t *)pud, PUD_SHIFT,
 429                                           addr, next, floor, ceiling);
 430                 }
 431         } while (addr = next, addr != end);
 432
 433         start &= PGDIR_MASK;
 434         if (start < floor)
 435                 return;
 436         if (ceiling) {
 437                 ceiling &= PGDIR_MASK;
 438                 if (!ceiling)
 439                         return;
 440         }
 441         if (end - 1 > ceiling - 1)
 442                 return;
 443
 444         pud = pud_offset(pgd, start);
 445         pgd_clear(pgd);
 446         pud_free_tlb(tlb, pud, start);
 447         mm_dec_nr_puds(tlb->mm);
 448 }
 449
 450 /*
 451  * This function frees user-level page tables of a process.
 452  */
 453 void hugetlb_free_pgd_range(struct mmu_gather *tlb,
 454                             unsigned long addr, unsigned long end,
 455                             unsigned long floor, unsigned long ceiling)
 456 {
 457         pgd_t *pgd;
 458         unsigned long next;
 459
 460         /*
 461          * Because there are a number of different possible pagetable
 462          * layouts for hugepage ranges, we limit knowledge of how
 463          * things should be laid out to the allocation path
 464          * (huge_pte_alloc(), above).  Everything else works out the
 465          * structure as it goes from information in the hugepd
 466          * pointers.  That means that we can't here use the
 467          * optimization used in the normal page free_pgd_range(), of
 468          * checking whether we're actually covering a large enough
 469          * range to have to do anything at the top level of the walk
 470          * instead of at the bottom.
 471          *
 472          * To make sense of this, you should probably go read the big
 473          * block comment at the top of the normal free_pgd_range(),
 474          * too.
 475          */
 476
 477         do {
 478                 next = pgd_addr_end(addr, end);
 479                 pgd = pgd_offset(tlb->mm, addr);
 480                 if (!is_hugepd(__hugepd(pgd_val(*pgd)))) {
 481                         if (pgd_none_or_clear_bad(pgd))
 482                                 continue;
 483                         hugetlb_free_pud_range(tlb, pgd, addr, next, floor, ceiling);
 484                 } else {
 485                         unsigned long more;
 486                         /*
 487                          * Increment next by the size of the huge mapping since
 488                          * there may be more than one entry at the pgd level
 489                          * for a single hugepage, but all of them point to the
 490                          * same kmem cache that holds the hugepte.
 491                          */
 492                         more = addr + (1 << hugepd_shift(*(hugepd_t *)pgd));
 493                         if (more > next)
 494                                 next = more;
 495
 496                         free_hugepd_range(tlb, (hugepd_t *)pgd, PGDIR_SHIFT,
 497                                           addr, next, floor, ceiling);
 498                 }
 499         } while (addr = next, addr != end);
 500 }
 501
 502 struct page *follow_huge_pd(struct vm_area_struct *vma,
 503                             unsigned long address, hugepd_t hpd,
 504                             int flags, int pdshift)
 505 {
 506         pte_t *ptep;
 507         spinlock_t *ptl;
 508         struct page *page = NULL;
 509         unsigned long mask;
 510         int shift = hugepd_shift(hpd);
 511         struct mm_struct *mm = vma->vm_mm;
 512
 513 retry:
 514         /*
 515          * hugepage directory entries are protected by mm->page_table_lock
 516          * Use this instead of huge_pte_lockptr
 517          */
 518         ptl = &mm->page_table_lock;
 519         spin_lock(ptl);
 520
 521         ptep = hugepte_offset(hpd, address, pdshift);
 522         if (pte_present(*ptep)) {
 523                 mask = (1UL << shift) - 1;
 524                 page = pte_page(*ptep);
 525                 page += ((address & mask) >> PAGE_SHIFT);
 526                 if (flags & FOLL_GET)
 527                         get_page(page);
 528         } else {
 529                 if (is_hugetlb_entry_migration(*ptep)) {
 530                         spin_unlock(ptl);
 531                         __migration_entry_wait(mm, ptep, ptl);
 532                         goto retry;
 533                 }
 534         }
 535         spin_unlock(ptl);
 536         return page;
 537 }
 538
 539 static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
 540                                       unsigned long sz)
 541 {
 542         unsigned long __boundary = (addr + sz) & ~(sz-1);
 543         return (__boundary - 1 < end - 1) ? __boundary : end;
 544 }
 545
 546 int gup_huge_pd(hugepd_t hugepd, unsigned long addr, unsigned pdshift,
 547                 unsigned long end, int write, struct page **pages, int *nr)
 548 {
 549         pte_t *ptep;
 550         unsigned long sz = 1UL << hugepd_shift(hugepd);
 551         unsigned long next;
 552
 553         ptep = hugepte_offset(hugepd, addr, pdshift);
 554         do {
 555                 next = hugepte_addr_end(addr, end, sz);
 556                 if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
 557                         return 0;
 558         } while (ptep++, addr = next, addr != end);
 559
 560         return 1;
 561 }
 562
 563 #ifdef CONFIG_PPC_MM_SLICES
 564 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 565                                         unsigned long len, unsigned long pgoff,
 566                                         unsigned long flags)
 567 {
 568         struct hstate *hstate = hstate_file(file);
 569         int mmu_psize = shift_to_mmu_psize(huge_page_shift(hstate));
 570
 571 #ifdef CONFIG_PPC_RADIX_MMU
 572         if (radix_enabled())
 573                 return radix__hugetlb_get_unmapped_area(file, addr, len,
 574                                                        pgoff, flags);
 575 #endif
 576         return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1);
 577 }
 578 #endif
 579
 580 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
 581 {
 582 #ifdef CONFIG_PPC_MM_SLICES
 583         /* With radix we don't use slice, so derive it from vma*/
 584         if (!radix_enabled()) {
 585                 unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);
 586
 587                 return 1UL << mmu_psize_to_shift(psize);
 588         }
 589 #endif
 590         return vma_kernel_pagesize(vma);
 591 }
 592
 593 static inline bool is_power_of_4(unsigned long x)
 594 {
 595         if (is_power_of_2(x))
 596                 return (__ilog2(x) % 2) ? false : true;
 597         return false;
 598 }
 599
 600 static int __init add_huge_page_size(unsigned long long size)
 601 {
 602         int shift = __ffs(size);
 603         int mmu_psize;
 604
 605         /* Check that it is a page size supported by the hardware and
 606          * that it fits within pagetable and slice limits. */
 607         if (size <= PAGE_SIZE)
 608                 return -EINVAL;
 609 #if defined(CONFIG_PPC_FSL_BOOK3E)
 610         if (!is_power_of_4(size))
 611                 return -EINVAL;
 612 #elif !defined(CONFIG_PPC_8xx)
 613         if (!is_power_of_2(size) || (shift > SLICE_HIGH_SHIFT))
 614                 return -EINVAL;
 615 #endif
 616
 617         if ((mmu_psize = shift_to_mmu_psize(shift)) < 0)
 618                 return -EINVAL;
 619
 620 #ifdef CONFIG_PPC_BOOK3S_64
 621         /*
 622          * We need to make sure that for different page sizes reported by
 623          * firmware we only add hugetlb support for page sizes that can be
 624          * supported by linux page table layout.
 625          * For now we have
 626          * Radix: 2M and 1G
 627          * Hash: 16M and 16G
 628          */
 629         if (radix_enabled()) {
 630                 if (mmu_psize != MMU_PAGE_2M && mmu_psize != MMU_PAGE_1G)
 631                         return -EINVAL;
 632         } else {
 633                 if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G)
 634                         return -EINVAL;
 635         }
 636 #endif
 637
 638         BUG_ON(mmu_psize_defs[mmu_psize].shift != shift);
 639
 640         /* Return if huge page size has already been setup */
 641         if (size_to_hstate(size))
 642                 return 0;
 643
 644         hugetlb_add_hstate(shift - PAGE_SHIFT);
 645
 646         return 0;
 647 }
 648
 649 static int __init hugepage_setup_sz(char *str)
 650 {
 651         unsigned long long size;
 652
 653         size = memparse(str, &str);
 654
 655         if (add_huge_page_size(size) != 0) {
 656                 hugetlb_bad_size();
 657                 pr_err("Invalid huge page size specified(%llu)\n", size);
 658         }
 659
 660         return 1;
 661 }
 662 __setup("hugepagesz=", hugepage_setup_sz);
 663
 664 struct kmem_cache *hugepte_cache;
 665 static int __init hugetlbpage_init(void)
 666 {
 667         int psize;
 668
 669         if (hugetlb_disabled) {
 670                 pr_info("HugeTLB support is disabled!\n");
 671                 return 0;
 672         }
 673
 674 #if !defined(CONFIG_PPC_FSL_BOOK3E) && !defined(CONFIG_PPC_8xx)
 675         if (!radix_enabled() && !mmu_has_feature(MMU_FTR_16M_PAGE))
 676                 return -ENODEV;
 677 #endif
 678         for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
 679                 unsigned shift;
 680                 unsigned pdshift;
 681
 682                 if (!mmu_psize_defs[psize].shift)
 683                         continue;
 684
 685                 shift = mmu_psize_to_shift(psize);
 686
 687 #ifdef CONFIG_PPC_BOOK3S_64
 688                 if (shift > PGDIR_SHIFT)
 689                         continue;
 690                 else if (shift > PUD_SHIFT)
 691                         pdshift = PGDIR_SHIFT;
 692                 else if (shift > PMD_SHIFT)
 693                         pdshift = PUD_SHIFT;
 694                 else
 695                         pdshift = PMD_SHIFT;
 696 #else
 697                 if (shift < PUD_SHIFT)
 698                         pdshift = PMD_SHIFT;
 699                 else if (shift < PGDIR_SHIFT)
 700                         pdshift = PUD_SHIFT;
 701                 else
 702                         pdshift = PGDIR_SHIFT;
 703 #endif
 704
 705                 if (add_huge_page_size(1ULL << shift) < 0)
 706                         continue;
 707                 /*
 708                  * if we have pdshift and shift value same, we don't
 709                  * use pgt cache for hugepd.
 710                  */
 711                 if (pdshift > shift)
 712                         pgtable_cache_add(pdshift - shift, NULL);
 713 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 714                 else if (!hugepte_cache) {
 715                         /*
 716                          * Create a kmem cache for hugeptes.  The bottom bits in
 717                          * the pte have size information encoded in them, so
 718                          * align them to allow this
 719                          */
 720                         hugepte_cache = kmem_cache_create("hugepte-cache",
 721                                                           sizeof(pte_t),
 722                                                           HUGEPD_SHIFT_MASK + 1,
 723                                                           0, NULL);
 724                         if (hugepte_cache == NULL)
 725                                 panic("%s: Unable to create kmem cache "
 726                                       "for hugeptes\n", __func__);
 727
 728                 }
 729 #endif
 730         }
 731
 732 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 733         /* Default hpage size = 4M on FSL_BOOK3E and 512k on 8xx */
 734         if (mmu_psize_defs[MMU_PAGE_4M].shift)
 735                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_4M].shift;
 736         else if (mmu_psize_defs[MMU_PAGE_512K].shift)
 737                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_512K].shift;
 738 #else
 739         /* Set default large page size. Currently, we pick 16M or 1M
 740          * depending on what is available
 741          */
 742         if (mmu_psize_defs[MMU_PAGE_16M].shift)
 743                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_16M].shift;
 744         else if (mmu_psize_defs[MMU_PAGE_1M].shift)
 745                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_1M].shift;
 746         else if (mmu_psize_defs[MMU_PAGE_2M].shift)
 747                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_2M].shift;
 748 #endif
 749         return 0;
 750 }
 751
 752 arch_initcall(hugetlbpage_init);
 753
 754 void flush_dcache_icache_hugepage(struct page *page)
 755 {
 756         int i;
 757         void *start;
 758
 759         BUG_ON(!PageCompound(page));
 760
 761         for (i = 0; i < (1UL << compound_order(page)); i++) {
 762                 if (!PageHighMem(page)) {
 763                         __flush_dcache_icache(page_address(page+i));
 764                 } else {
 765                         start = kmap_atomic(page+i);
 766                         __flush_dcache_icache(start);
 767                         kunmap_atomic(start);
 768                 }
 769         }
 770 }
 771
 772 #endif /* CONFIG_HUGETLB_PAGE */
 773
 774 /*
 775  * We have 4 cases for pgds and pmds:
 776  * (1) invalid (all zeroes)
 777  * (2) pointer to next table, as normal; bottom 6 bits == 0
 778  * (3) leaf pte for huge page _PAGE_PTE set
 779  * (4) hugepd pointer, _PAGE_PTE = 0 and bits [2..6] indicate size of table
 780  *
 781  * So long as we atomically load page table pointers we are safe against teardown,
 782  * we can follow the address down to the the page and take a ref on it.
 783  * This function need to be called with interrupts disabled. We use this variant
 784  * when we have MSR[EE] = 0 but the paca->irq_soft_mask = IRQS_ENABLED
 785  */
 786 pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
 787                         bool *is_thp, unsigned *hpage_shift)
 788 {
 789         pgd_t pgd, *pgdp;
 790         pud_t pud, *pudp;
 791         pmd_t pmd, *pmdp;
 792         pte_t *ret_pte;
 793         hugepd_t *hpdp = NULL;
 794         unsigned pdshift = PGDIR_SHIFT;
 795
 796         if (hpage_shift)
 797                 *hpage_shift = 0;
 798
 799         if (is_thp)
 800                 *is_thp = false;
 801
 802         pgdp = pgdir + pgd_index(ea);
 803         pgd  = READ_ONCE(*pgdp);
 804         /*
 805          * Always operate on the local stack value. This make sure the
 806          * value don't get updated by a parallel THP split/collapse,
 807          * page fault or a page unmap. The return pte_t * is still not
 808          * stable. So should be checked there for above conditions.
 809          */
 810         if (pgd_none(pgd))
 811                 return NULL;
 812         else if (pgd_huge(pgd)) {
 813                 ret_pte = (pte_t *) pgdp;
 814                 goto out;
 815         } else if (is_hugepd(__hugepd(pgd_val(pgd))))
 816                 hpdp = (hugepd_t *)&pgd;
 817         else {
 818                 /*
 819                  * Even if we end up with an unmap, the pgtable will not
 820                  * be freed, because we do an rcu free and here we are
 821                  * irq disabled
 822                  */
 823                 pdshift = PUD_SHIFT;
 824                 pudp = pud_offset(&pgd, ea);
 825                 pud  = READ_ONCE(*pudp);
 826
 827                 if (pud_none(pud))
 828                         return NULL;
 829                 else if (pud_huge(pud)) {
 830                         ret_pte = (pte_t *) pudp;
 831                         goto out;
 832                 } else if (is_hugepd(__hugepd(pud_val(pud))))
 833                         hpdp = (hugepd_t *)&pud;
 834                 else {
 835                         pdshift = PMD_SHIFT;
 836                         pmdp = pmd_offset(&pud, ea);
 837                         pmd  = READ_ONCE(*pmdp);
 838                         /*
 839                          * A hugepage collapse is captured by pmd_none, because
 840                          * it mark the pmd none and do a hpte invalidate.
 841                          */
 842                         if (pmd_none(pmd))
 843                                 return NULL;
 844
 845                         if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
 846                                 if (is_thp)
 847                                         *is_thp = true;
 848                                 ret_pte = (pte_t *) pmdp;
 849                                 goto out;
 850                         }
 851
 852                         if (pmd_huge(pmd)) {
 853                                 ret_pte = (pte_t *) pmdp;
 854                                 goto out;
 855                         } else if (is_hugepd(__hugepd(pmd_val(pmd))))
 856                                 hpdp = (hugepd_t *)&pmd;
 857                         else
 858                                 return pte_offset_kernel(&pmd, ea);
 859                 }
 860         }
 861         if (!hpdp)
 862                 return NULL;
 863
 864         ret_pte = hugepte_offset(*hpdp, ea, pdshift);
 865         pdshift = hugepd_shift(*hpdp);
 866 out:
 867         if (hpage_shift)
 868                 *hpage_shift = pdshift;
 869         return ret_pte;
 870 }
 871 EXPORT_SYMBOL_GPL(__find_linux_pte);
 872
 873 int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 874                 unsigned long end, int write, struct page **pages, int *nr)
 875 {
 876         unsigned long pte_end;
 877         struct page *head, *page;
 878         pte_t pte;
 879         int refs;
 880
 881         pte_end = (addr + sz) & ~(sz-1);
 882         if (pte_end < end)
 883                 end = pte_end;
 884
 885         pte = READ_ONCE(*ptep);
 886
 887         if (!pte_access_permitted(pte, write))
 888                 return 0;
 889
 890         /* hugepages are never "special" */
 891         VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
 892
 893         refs = 0;
 894         head = pte_page(pte);
 895
 896         page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
 897         do {
 898                 VM_BUG_ON(compound_head(page) != head);
 899                 pages[*nr] = page;
 900                 (*nr)++;
 901                 page++;
 902                 refs++;
 903         } while (addr += PAGE_SIZE, addr != end);
 904
 905         if (!page_cache_add_speculative(head, refs)) {
 906                 *nr -= refs;
 907                 return 0;
 908         }
 909
 910         if (unlikely(pte_val(pte) != pte_val(*ptep))) {
 911                 /* Could be optimized better */
 912                 *nr -= refs;
 913                 while (refs--)
 914                         put_page(head);
 915                 return 0;
 916         }
 917
 918         return 1;
 919 }