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 unsigned int HPAGE_SHIFT;
  39 EXPORT_SYMBOL(HPAGE_SHIFT);
  40
  41 #define hugepd_none(hpd)        (hpd_val(hpd) == 0)
  42
  43 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long sz)
  44 {
  45         /*
  46          * Only called for hugetlbfs pages, hence can ignore THP and the
  47          * irq disabled walk.
  48          */
  49         return __find_linux_pte(mm->pgd, addr, NULL, NULL);
  50 }
  51
  52 static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
  53                            unsigned long address, unsigned pdshift, unsigned pshift)
  54 {
  55         struct kmem_cache *cachep;
  56         pte_t *new;
  57         int i;
  58         int num_hugepd;
  59
  60         if (pshift >= pdshift) {
  61                 cachep = hugepte_cache;
  62                 num_hugepd = 1 << (pshift - pdshift);
  63         } else {
  64                 cachep = PGT_CACHE(pdshift - pshift);
  65                 num_hugepd = 1;
  66         }
  67
  68         new = kmem_cache_zalloc(cachep, pgtable_gfp_flags(mm, GFP_KERNEL));
  69
  70         BUG_ON(pshift > HUGEPD_SHIFT_MASK);
  71         BUG_ON((unsigned long)new & HUGEPD_SHIFT_MASK);
  72
  73         if (! new)
  74                 return -ENOMEM;
  75
  76         /*
  77          * Make sure other cpus find the hugepd set only after a
  78          * properly initialized page table is visible to them.
  79          * For more details look for comment in __pte_alloc().
  80          */
  81         smp_wmb();
  82
  83         spin_lock(&mm->page_table_lock);
  84
  85         /*
  86          * We have multiple higher-level entries that point to the same
  87          * actual pte location.  Fill in each as we go and backtrack on error.
  88          * We need all of these so the DTLB pgtable walk code can find the
  89          * right higher-level entry without knowing if it's a hugepage or not.
  90          */
  91         for (i = 0; i < num_hugepd; i++, hpdp++) {
  92                 if (unlikely(!hugepd_none(*hpdp)))
  93                         break;
  94                 else {
  95 #ifdef CONFIG_PPC_BOOK3S_64
  96                         *hpdp = __hugepd(__pa(new) |
  97                                          (shift_to_mmu_psize(pshift) << 2));
  98 #elif defined(CONFIG_PPC_8xx)
  99                         *hpdp = __hugepd(__pa(new) |
 100                                          (pshift == PAGE_SHIFT_8M ? _PMD_PAGE_8M :
 101                                           _PMD_PAGE_512K) | _PMD_PRESENT);
 102 #else
 103                         /* We use the old format for PPC_FSL_BOOK3E */
 104                         *hpdp = __hugepd(((unsigned long)new & ~PD_HUGE) | pshift);
 105 #endif
 106                 }
 107         }
 108         /* If we bailed from the for loop early, an error occurred, clean up */
 109         if (i < num_hugepd) {
 110                 for (i = i - 1 ; i >= 0; i--, hpdp--)
 111                         *hpdp = __hugepd(0);
 112                 kmem_cache_free(cachep, new);
 113         }
 114         spin_unlock(&mm->page_table_lock);
 115         return 0;
 116 }
 117
 118 /*
 119  * These macros define how to determine which level of the page table holds
 120  * the hpdp.
 121  */
 122 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 123 #define HUGEPD_PGD_SHIFT PGDIR_SHIFT
 124 #define HUGEPD_PUD_SHIFT PUD_SHIFT
 125 #else
 126 #define HUGEPD_PGD_SHIFT PUD_SHIFT
 127 #define HUGEPD_PUD_SHIFT PMD_SHIFT
 128 #endif
 129
 130 /*
 131  * At this point we do the placement change only for BOOK3S 64. This would
 132  * possibly work on other subarchs.
 133  */
 134 pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz)
 135 {
 136         pgd_t *pg;
 137         pud_t *pu;
 138         pmd_t *pm;
 139         hugepd_t *hpdp = NULL;
 140         unsigned pshift = __ffs(sz);
 141         unsigned pdshift = PGDIR_SHIFT;
 142
 143         addr &= ~(sz-1);
 144         pg = pgd_offset(mm, addr);
 145
 146 #ifdef CONFIG_PPC_BOOK3S_64
 147         if (pshift == PGDIR_SHIFT)
 148                 /* 16GB huge page */
 149                 return (pte_t *) pg;
 150         else if (pshift > PUD_SHIFT)
 151                 /*
 152                  * We need to use hugepd table
 153                  */
 154                 hpdp = (hugepd_t *)pg;
 155         else {
 156                 pdshift = PUD_SHIFT;
 157                 pu = pud_alloc(mm, pg, addr);
 158                 if (pshift == PUD_SHIFT)
 159                         return (pte_t *)pu;
 160                 else if (pshift > PMD_SHIFT)
 161                         hpdp = (hugepd_t *)pu;
 162                 else {
 163                         pdshift = PMD_SHIFT;
 164                         pm = pmd_alloc(mm, pu, addr);
 165                         if (pshift == PMD_SHIFT)
 166                                 /* 16MB hugepage */
 167                                 return (pte_t *)pm;
 168                         else
 169                                 hpdp = (hugepd_t *)pm;
 170                 }
 171         }
 172 #else
 173         if (pshift >= HUGEPD_PGD_SHIFT) {
 174                 hpdp = (hugepd_t *)pg;
 175         } else {
 176                 pdshift = PUD_SHIFT;
 177                 pu = pud_alloc(mm, pg, addr);
 178                 if (pshift >= HUGEPD_PUD_SHIFT) {
 179                         hpdp = (hugepd_t *)pu;
 180                 } else {
 181                         pdshift = PMD_SHIFT;
 182                         pm = pmd_alloc(mm, pu, addr);
 183                         hpdp = (hugepd_t *)pm;
 184                 }
 185         }
 186 #endif
 187         if (!hpdp)
 188                 return NULL;
 189
 190         BUG_ON(!hugepd_none(*hpdp) && !hugepd_ok(*hpdp));
 191
 192         if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr, pdshift, pshift))
 193                 return NULL;
 194
 195         return hugepte_offset(*hpdp, addr, pdshift);
 196 }
 197
 198 #ifdef CONFIG_PPC_BOOK3S_64
 199 /*
 200  * Tracks gpages after the device tree is scanned and before the
 201  * huge_boot_pages list is ready on pseries.
 202  */
 203 #define MAX_NUMBER_GPAGES       1024
 204 __initdata static u64 gpage_freearray[MAX_NUMBER_GPAGES];
 205 __initdata static unsigned nr_gpages;
 206
 207 /*
 208  * Build list of addresses of gigantic pages.  This function is used in early
 209  * boot before the buddy allocator is setup.
 210  */
 211 void __init pseries_add_gpage(u64 addr, u64 page_size, unsigned long number_of_pages)
 212 {
 213         if (!addr)
 214                 return;
 215         while (number_of_pages > 0) {
 216                 gpage_freearray[nr_gpages] = addr;
 217                 nr_gpages++;
 218                 number_of_pages--;
 219                 addr += page_size;
 220         }
 221 }
 222
 223 int __init pseries_alloc_bootmem_huge_page(struct hstate *hstate)
 224 {
 225         struct huge_bootmem_page *m;
 226         if (nr_gpages == 0)
 227                 return 0;
 228         m = phys_to_virt(gpage_freearray[--nr_gpages]);
 229         gpage_freearray[nr_gpages] = 0;
 230         list_add(&m->list, &huge_boot_pages);
 231         m->hstate = hstate;
 232         return 1;
 233 }
 234 #endif
 235
 236
 237 int __init alloc_bootmem_huge_page(struct hstate *h)
 238 {
 239
 240 #ifdef CONFIG_PPC_BOOK3S_64
 241         if (firmware_has_feature(FW_FEATURE_LPAR) && !radix_enabled())
 242                 return pseries_alloc_bootmem_huge_page(h);
 243 #endif
 244         return __alloc_bootmem_huge_page(h);
 245 }
 246
 247 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 248 #define HUGEPD_FREELIST_SIZE \
 249         ((PAGE_SIZE - sizeof(struct hugepd_freelist)) / sizeof(pte_t))
 250
 251 struct hugepd_freelist {
 252         struct rcu_head rcu;
 253         unsigned int index;
 254         void *ptes[0];
 255 };
 256
 257 static DEFINE_PER_CPU(struct hugepd_freelist *, hugepd_freelist_cur);
 258
 259 static void hugepd_free_rcu_callback(struct rcu_head *head)
 260 {
 261         struct hugepd_freelist *batch =
 262                 container_of(head, struct hugepd_freelist, rcu);
 263         unsigned int i;
 264
 265         for (i = 0; i < batch->index; i++)
 266                 kmem_cache_free(hugepte_cache, batch->ptes[i]);
 267
 268         free_page((unsigned long)batch);
 269 }
 270
 271 static void hugepd_free(struct mmu_gather *tlb, void *hugepte)
 272 {
 273         struct hugepd_freelist **batchp;
 274
 275         batchp = &get_cpu_var(hugepd_freelist_cur);
 276
 277         if (atomic_read(&tlb->mm->mm_users) < 2 ||
 278             mm_is_thread_local(tlb->mm)) {
 279                 kmem_cache_free(hugepte_cache, hugepte);
 280                 put_cpu_var(hugepd_freelist_cur);
 281                 return;
 282         }
 283
 284         if (*batchp == NULL) {
 285                 *batchp = (struct hugepd_freelist *)__get_free_page(GFP_ATOMIC);
 286                 (*batchp)->index = 0;
 287         }
 288
 289         (*batchp)->ptes[(*batchp)->index++] = hugepte;
 290         if ((*batchp)->index == HUGEPD_FREELIST_SIZE) {
 291                 call_rcu_sched(&(*batchp)->rcu, hugepd_free_rcu_callback);
 292                 *batchp = NULL;
 293         }
 294         put_cpu_var(hugepd_freelist_cur);
 295 }
 296 #else
 297 static inline void hugepd_free(struct mmu_gather *tlb, void *hugepte) {}
 298 #endif
 299
 300 static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshift,
 301                               unsigned long start, unsigned long end,
 302                               unsigned long floor, unsigned long ceiling)
 303 {
 304         pte_t *hugepte = hugepd_page(*hpdp);
 305         int i;
 306
 307         unsigned long pdmask = ~((1UL << pdshift) - 1);
 308         unsigned int num_hugepd = 1;
 309         unsigned int shift = hugepd_shift(*hpdp);
 310
 311         /* Note: On fsl the hpdp may be the first of several */
 312         if (shift > pdshift)
 313                 num_hugepd = 1 << (shift - pdshift);
 314
 315         start &= pdmask;
 316         if (start < floor)
 317                 return;
 318         if (ceiling) {
 319                 ceiling &= pdmask;
 320                 if (! ceiling)
 321                         return;
 322         }
 323         if (end - 1 > ceiling - 1)
 324                 return;
 325
 326         for (i = 0; i < num_hugepd; i++, hpdp++)
 327                 *hpdp = __hugepd(0);
 328
 329         if (shift >= pdshift)
 330                 hugepd_free(tlb, hugepte);
 331         else
 332                 pgtable_free_tlb(tlb, hugepte, 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 }
 437
 438 /*
 439  * This function frees user-level page tables of a process.
 440  */
 441 void hugetlb_free_pgd_range(struct mmu_gather *tlb,
 442                             unsigned long addr, unsigned long end,
 443                             unsigned long floor, unsigned long ceiling)
 444 {
 445         pgd_t *pgd;
 446         unsigned long next;
 447
 448         /*
 449          * Because there are a number of different possible pagetable
 450          * layouts for hugepage ranges, we limit knowledge of how
 451          * things should be laid out to the allocation path
 452          * (huge_pte_alloc(), above).  Everything else works out the
 453          * structure as it goes from information in the hugepd
 454          * pointers.  That means that we can't here use the
 455          * optimization used in the normal page free_pgd_range(), of
 456          * checking whether we're actually covering a large enough
 457          * range to have to do anything at the top level of the walk
 458          * instead of at the bottom.
 459          *
 460          * To make sense of this, you should probably go read the big
 461          * block comment at the top of the normal free_pgd_range(),
 462          * too.
 463          */
 464
 465         do {
 466                 next = pgd_addr_end(addr, end);
 467                 pgd = pgd_offset(tlb->mm, addr);
 468                 if (!is_hugepd(__hugepd(pgd_val(*pgd)))) {
 469                         if (pgd_none_or_clear_bad(pgd))
 470                                 continue;
 471                         hugetlb_free_pud_range(tlb, pgd, addr, next, floor, ceiling);
 472                 } else {
 473                         unsigned long more;
 474                         /*
 475                          * Increment next by the size of the huge mapping since
 476                          * there may be more than one entry at the pgd level
 477                          * for a single hugepage, but all of them point to the
 478                          * same kmem cache that holds the hugepte.
 479                          */
 480                         more = addr + (1 << hugepd_shift(*(hugepd_t *)pgd));
 481                         if (more > next)
 482                                 next = more;
 483
 484                         free_hugepd_range(tlb, (hugepd_t *)pgd, PGDIR_SHIFT,
 485                                           addr, next, floor, ceiling);
 486                 }
 487         } while (addr = next, addr != end);
 488 }
 489
 490 struct page *follow_huge_pd(struct vm_area_struct *vma,
 491                             unsigned long address, hugepd_t hpd,
 492                             int flags, int pdshift)
 493 {
 494         pte_t *ptep;
 495         spinlock_t *ptl;
 496         struct page *page = NULL;
 497         unsigned long mask;
 498         int shift = hugepd_shift(hpd);
 499         struct mm_struct *mm = vma->vm_mm;
 500
 501 retry:
 502         ptl = &mm->page_table_lock;
 503         spin_lock(ptl);
 504
 505         ptep = hugepte_offset(hpd, address, pdshift);
 506         if (pte_present(*ptep)) {
 507                 mask = (1UL << shift) - 1;
 508                 page = pte_page(*ptep);
 509                 page += ((address & mask) >> PAGE_SHIFT);
 510                 if (flags & FOLL_GET)
 511                         get_page(page);
 512         } else {
 513                 if (is_hugetlb_entry_migration(*ptep)) {
 514                         spin_unlock(ptl);
 515                         __migration_entry_wait(mm, ptep, ptl);
 516                         goto retry;
 517                 }
 518         }
 519         spin_unlock(ptl);
 520         return page;
 521 }
 522
 523 static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
 524                                       unsigned long sz)
 525 {
 526         unsigned long __boundary = (addr + sz) & ~(sz-1);
 527         return (__boundary - 1 < end - 1) ? __boundary : end;
 528 }
 529
 530 int gup_huge_pd(hugepd_t hugepd, unsigned long addr, unsigned pdshift,
 531                 unsigned long end, int write, struct page **pages, int *nr)
 532 {
 533         pte_t *ptep;
 534         unsigned long sz = 1UL << hugepd_shift(hugepd);
 535         unsigned long next;
 536
 537         ptep = hugepte_offset(hugepd, addr, pdshift);
 538         do {
 539                 next = hugepte_addr_end(addr, end, sz);
 540                 if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
 541                         return 0;
 542         } while (ptep++, addr = next, addr != end);
 543
 544         return 1;
 545 }
 546
 547 #ifdef CONFIG_PPC_MM_SLICES
 548 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 549                                         unsigned long len, unsigned long pgoff,
 550                                         unsigned long flags)
 551 {
 552         struct hstate *hstate = hstate_file(file);
 553         int mmu_psize = shift_to_mmu_psize(huge_page_shift(hstate));
 554
 555         if (radix_enabled())
 556                 return radix__hugetlb_get_unmapped_area(file, addr, len,
 557                                                        pgoff, flags);
 558         return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1);
 559 }
 560 #endif
 561
 562 unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
 563 {
 564 #ifdef CONFIG_PPC_MM_SLICES
 565         unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);
 566         /* With radix we don't use slice, so derive it from vma*/
 567         if (!radix_enabled())
 568                 return 1UL << mmu_psize_to_shift(psize);
 569 #endif
 570         if (!is_vm_hugetlb_page(vma))
 571                 return PAGE_SIZE;
 572
 573         return huge_page_size(hstate_vma(vma));
 574 }
 575
 576 static inline bool is_power_of_4(unsigned long x)
 577 {
 578         if (is_power_of_2(x))
 579                 return (__ilog2(x) % 2) ? false : true;
 580         return false;
 581 }
 582
 583 static int __init add_huge_page_size(unsigned long long size)
 584 {
 585         int shift = __ffs(size);
 586         int mmu_psize;
 587
 588         /* Check that it is a page size supported by the hardware and
 589          * that it fits within pagetable and slice limits. */
 590         if (size <= PAGE_SIZE)
 591                 return -EINVAL;
 592 #if defined(CONFIG_PPC_FSL_BOOK3E)
 593         if (!is_power_of_4(size))
 594                 return -EINVAL;
 595 #elif !defined(CONFIG_PPC_8xx)
 596         if (!is_power_of_2(size) || (shift > SLICE_HIGH_SHIFT))
 597                 return -EINVAL;
 598 #endif
 599
 600         if ((mmu_psize = shift_to_mmu_psize(shift)) < 0)
 601                 return -EINVAL;
 602
 603 #ifdef CONFIG_PPC_BOOK3S_64
 604         /*
 605          * We need to make sure that for different page sizes reported by
 606          * firmware we only add hugetlb support for page sizes that can be
 607          * supported by linux page table layout.
 608          * For now we have
 609          * Radix: 2M
 610          * Hash: 16M and 16G
 611          */
 612         if (radix_enabled()) {
 613                 if (mmu_psize != MMU_PAGE_2M) {
 614                         if (cpu_has_feature(CPU_FTR_POWER9_DD1) ||
 615                             (mmu_psize != MMU_PAGE_1G))
 616                                 return -EINVAL;
 617                 }
 618         } else {
 619                 if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G)
 620                         return -EINVAL;
 621         }
 622 #endif
 623
 624         BUG_ON(mmu_psize_defs[mmu_psize].shift != shift);
 625
 626         /* Return if huge page size has already been setup */
 627         if (size_to_hstate(size))
 628                 return 0;
 629
 630         hugetlb_add_hstate(shift - PAGE_SHIFT);
 631
 632         return 0;
 633 }
 634
 635 static int __init hugepage_setup_sz(char *str)
 636 {
 637         unsigned long long size;
 638
 639         size = memparse(str, &str);
 640
 641         if (add_huge_page_size(size) != 0) {
 642                 hugetlb_bad_size();
 643                 pr_err("Invalid huge page size specified(%llu)\n", size);
 644         }
 645
 646         return 1;
 647 }
 648 __setup("hugepagesz=", hugepage_setup_sz);
 649
 650 struct kmem_cache *hugepte_cache;
 651 static int __init hugetlbpage_init(void)
 652 {
 653         int psize;
 654
 655 #if !defined(CONFIG_PPC_FSL_BOOK3E) && !defined(CONFIG_PPC_8xx)
 656         if (!radix_enabled() && !mmu_has_feature(MMU_FTR_16M_PAGE))
 657                 return -ENODEV;
 658 #endif
 659         for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
 660                 unsigned shift;
 661                 unsigned pdshift;
 662
 663                 if (!mmu_psize_defs[psize].shift)
 664                         continue;
 665
 666                 shift = mmu_psize_to_shift(psize);
 667
 668                 if (add_huge_page_size(1ULL << shift) < 0)
 669                         continue;
 670
 671                 if (shift < HUGEPD_PUD_SHIFT)
 672                         pdshift = PMD_SHIFT;
 673                 else if (shift < HUGEPD_PGD_SHIFT)
 674                         pdshift = PUD_SHIFT;
 675                 else
 676                         pdshift = PGDIR_SHIFT;
 677                 /*
 678                  * if we have pdshift and shift value same, we don't
 679                  * use pgt cache for hugepd.
 680                  */
 681                 if (pdshift > shift)
 682                         pgtable_cache_add(pdshift - shift, NULL);
 683 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 684                 else if (!hugepte_cache) {
 685                         /*
 686                          * Create a kmem cache for hugeptes.  The bottom bits in
 687                          * the pte have size information encoded in them, so
 688                          * align them to allow this
 689                          */
 690                         hugepte_cache = kmem_cache_create("hugepte-cache",
 691                                                           sizeof(pte_t),
 692                                                           HUGEPD_SHIFT_MASK + 1,
 693                                                           0, NULL);
 694                         if (hugepte_cache == NULL)
 695                                 panic("%s: Unable to create kmem cache "
 696                                       "for hugeptes\n", __func__);
 697
 698                 }
 699 #endif
 700         }
 701
 702 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 703         /* Default hpage size = 4M on FSL_BOOK3E and 512k on 8xx */
 704         if (mmu_psize_defs[MMU_PAGE_4M].shift)
 705                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_4M].shift;
 706         else if (mmu_psize_defs[MMU_PAGE_512K].shift)
 707                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_512K].shift;
 708 #else
 709         /* Set default large page size. Currently, we pick 16M or 1M
 710          * depending on what is available
 711          */
 712         if (mmu_psize_defs[MMU_PAGE_16M].shift)
 713                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_16M].shift;
 714         else if (mmu_psize_defs[MMU_PAGE_1M].shift)
 715                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_1M].shift;
 716         else if (mmu_psize_defs[MMU_PAGE_2M].shift)
 717                 HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_2M].shift;
 718 #endif
 719         return 0;
 720 }
 721
 722 arch_initcall(hugetlbpage_init);
 723
 724 void flush_dcache_icache_hugepage(struct page *page)
 725 {
 726         int i;
 727         void *start;
 728
 729         BUG_ON(!PageCompound(page));
 730
 731         for (i = 0; i < (1UL << compound_order(page)); i++) {
 732                 if (!PageHighMem(page)) {
 733                         __flush_dcache_icache(page_address(page+i));
 734                 } else {
 735                         start = kmap_atomic(page+i);
 736                         __flush_dcache_icache(start);
 737                         kunmap_atomic(start);
 738                 }
 739         }
 740 }
 741
 742 #endif /* CONFIG_HUGETLB_PAGE */
 743
 744 /*
 745  * We have 4 cases for pgds and pmds:
 746  * (1) invalid (all zeroes)
 747  * (2) pointer to next table, as normal; bottom 6 bits == 0
 748  * (3) leaf pte for huge page _PAGE_PTE set
 749  * (4) hugepd pointer, _PAGE_PTE = 0 and bits [2..6] indicate size of table
 750  *
 751  * So long as we atomically load page table pointers we are safe against teardown,
 752  * we can follow the address down to the the page and take a ref on it.
 753  * This function need to be called with interrupts disabled. We use this variant
 754  * when we have MSR[EE] = 0 but the paca->soft_enabled = 1
 755  */
 756 pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
 757                         bool *is_thp, unsigned *hpage_shift)
 758 {
 759         pgd_t pgd, *pgdp;
 760         pud_t pud, *pudp;
 761         pmd_t pmd, *pmdp;
 762         pte_t *ret_pte;
 763         hugepd_t *hpdp = NULL;
 764         unsigned pdshift = PGDIR_SHIFT;
 765
 766         if (hpage_shift)
 767                 *hpage_shift = 0;
 768
 769         if (is_thp)
 770                 *is_thp = false;
 771
 772         pgdp = pgdir + pgd_index(ea);
 773         pgd  = READ_ONCE(*pgdp);
 774         /*
 775          * Always operate on the local stack value. This make sure the
 776          * value don't get updated by a parallel THP split/collapse,
 777          * page fault or a page unmap. The return pte_t * is still not
 778          * stable. So should be checked there for above conditions.
 779          */
 780         if (pgd_none(pgd))
 781                 return NULL;
 782         else if (pgd_huge(pgd)) {
 783                 ret_pte = (pte_t *) pgdp;
 784                 goto out;
 785         } else if (is_hugepd(__hugepd(pgd_val(pgd))))
 786                 hpdp = (hugepd_t *)&pgd;
 787         else {
 788                 /*
 789                  * Even if we end up with an unmap, the pgtable will not
 790                  * be freed, because we do an rcu free and here we are
 791                  * irq disabled
 792                  */
 793                 pdshift = PUD_SHIFT;
 794                 pudp = pud_offset(&pgd, ea);
 795                 pud  = READ_ONCE(*pudp);
 796
 797                 if (pud_none(pud))
 798                         return NULL;
 799                 else if (pud_huge(pud)) {
 800                         ret_pte = (pte_t *) pudp;
 801                         goto out;
 802                 } else if (is_hugepd(__hugepd(pud_val(pud))))
 803                         hpdp = (hugepd_t *)&pud;
 804                 else {
 805                         pdshift = PMD_SHIFT;
 806                         pmdp = pmd_offset(&pud, ea);
 807                         pmd  = READ_ONCE(*pmdp);
 808                         /*
 809                          * A hugepage collapse is captured by pmd_none, because
 810                          * it mark the pmd none and do a hpte invalidate.
 811                          */
 812                         if (pmd_none(pmd))
 813                                 return NULL;
 814
 815                         if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
 816                                 if (is_thp)
 817                                         *is_thp = true;
 818                                 ret_pte = (pte_t *) pmdp;
 819                                 goto out;
 820                         }
 821
 822                         if (pmd_huge(pmd)) {
 823                                 ret_pte = (pte_t *) pmdp;
 824                                 goto out;
 825                         } else if (is_hugepd(__hugepd(pmd_val(pmd))))
 826                                 hpdp = (hugepd_t *)&pmd;
 827                         else
 828                                 return pte_offset_kernel(&pmd, ea);
 829                 }
 830         }
 831         if (!hpdp)
 832                 return NULL;
 833
 834         ret_pte = hugepte_offset(*hpdp, ea, pdshift);
 835         pdshift = hugepd_shift(*hpdp);
 836 out:
 837         if (hpage_shift)
 838                 *hpage_shift = pdshift;
 839         return ret_pte;
 840 }
 841 EXPORT_SYMBOL_GPL(__find_linux_pte);
 842
 843 int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
 844                 unsigned long end, int write, struct page **pages, int *nr)
 845 {
 846         unsigned long pte_end;
 847         struct page *head, *page;
 848         pte_t pte;
 849         int refs;
 850
 851         pte_end = (addr + sz) & ~(sz-1);
 852         if (pte_end < end)
 853                 end = pte_end;
 854
 855         pte = READ_ONCE(*ptep);
 856
 857         if (!pte_present(pte) || !pte_read(pte))
 858                 return 0;
 859         if (write && !pte_write(pte))
 860                 return 0;
 861
 862         /* hugepages are never "special" */
 863         VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
 864
 865         refs = 0;
 866         head = pte_page(pte);
 867
 868         page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
 869         do {
 870                 VM_BUG_ON(compound_head(page) != head);
 871                 pages[*nr] = page;
 872                 (*nr)++;
 873                 page++;
 874                 refs++;
 875         } while (addr += PAGE_SIZE, addr != end);
 876
 877         if (!page_cache_add_speculative(head, refs)) {
 878                 *nr -= refs;
 879                 return 0;
 880         }
 881
 882         if (unlikely(pte_val(pte) != pte_val(*ptep))) {
 883                 /* Could be optimized better */
 884                 *nr -= refs;
 885                 while (refs--)
 886                         put_page(head);
 887                 return 0;
 888         }
 889
 890         return 1;
 891 }