arch/arm64/mm/hugetlbpage.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * arch/arm64/mm/hugetlbpage.c
   4  *
   5  * Copyright (C) 2013 Linaro Ltd.
   6  *
   7  * Based on arch/x86/mm/hugetlbpage.c.
   8  */
   9
  10 #include <linux/init.h>
  11 #include <linux/fs.h>
  12 #include <linux/mm.h>
  13 #include <linux/hugetlb.h>
  14 #include <linux/pagemap.h>
  15 #include <linux/err.h>
  16 #include <linux/sysctl.h>
  17 #include <asm/mman.h>
  18 #include <asm/tlb.h>
  19 #include <asm/tlbflush.h>
  20
  21 /*
  22  * HugeTLB Support Matrix
  23  *
  24  * ---------------------------------------------------
  25  * | Page Size | CONT PTE |  PMD  | CONT PMD |  PUD  |
  26  * ---------------------------------------------------
  27  * |     4K    |   64K    |   2M  |    32M   |   1G  |
  28  * |    16K    |    2M    |  32M  |     1G   |       |
  29  * |    64K    |    2M    | 512M  |    16G   |       |
  30  * ---------------------------------------------------
  31  */
  32
  33 /*
  34  * Reserve CMA areas for the largest supported gigantic
  35  * huge page when requested. Any other smaller gigantic
  36  * huge pages could still be served from those areas.
  37  */
  38 #ifdef CONFIG_CMA
  39 void __init arm64_hugetlb_cma_reserve(void)
  40 {
  41         int order;
  42
  43         if (pud_sect_supported())
  44                 order = PUD_SHIFT - PAGE_SHIFT;
  45         else
  46                 order = CONT_PMD_SHIFT - PAGE_SHIFT;
  47
  48         hugetlb_cma_reserve(order);
  49 }
  50 #endif /* CONFIG_CMA */
  51
  52 static bool __hugetlb_valid_size(unsigned long size)
  53 {
  54         switch (size) {
  55 #ifndef __PAGETABLE_PMD_FOLDED
  56         case PUD_SIZE:
  57                 return pud_sect_supported();
  58 #endif
  59         case CONT_PMD_SIZE:
  60         case PMD_SIZE:
  61         case CONT_PTE_SIZE:
  62                 return true;
  63         }
  64
  65         return false;
  66 }
  67
  68 #ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
  69 bool arch_hugetlb_migration_supported(struct hstate *h)
  70 {
  71         size_t pagesize = huge_page_size(h);
  72
  73         if (!__hugetlb_valid_size(pagesize)) {
  74                 pr_warn("%s: unrecognized huge page size 0x%lx\n",
  75                         __func__, pagesize);
  76                 return false;
  77         }
  78         return true;
  79 }
  80 #endif
  81
  82 static int find_num_contig(struct mm_struct *mm, unsigned long addr,
  83                            pte_t *ptep, size_t *pgsize)
  84 {
  85         pgd_t *pgdp = pgd_offset(mm, addr);
  86         p4d_t *p4dp;
  87         pud_t *pudp;
  88         pmd_t *pmdp;
  89
  90         *pgsize = PAGE_SIZE;
  91         p4dp = p4d_offset(pgdp, addr);
  92         pudp = pud_offset(p4dp, addr);
  93         pmdp = pmd_offset(pudp, addr);
  94         if ((pte_t *)pmdp == ptep) {
  95                 *pgsize = PMD_SIZE;
  96                 return CONT_PMDS;
  97         }
  98         return CONT_PTES;
  99 }
 100
 101 static inline int num_contig_ptes(unsigned long size, size_t *pgsize)
 102 {
 103         int contig_ptes = 0;
 104
 105         *pgsize = size;
 106
 107         switch (size) {
 108 #ifndef __PAGETABLE_PMD_FOLDED
 109         case PUD_SIZE:
 110                 if (pud_sect_supported())
 111                         contig_ptes = 1;
 112                 break;
 113 #endif
 114         case PMD_SIZE:
 115                 contig_ptes = 1;
 116                 break;
 117         case CONT_PMD_SIZE:
 118                 *pgsize = PMD_SIZE;
 119                 contig_ptes = CONT_PMDS;
 120                 break;
 121         case CONT_PTE_SIZE:
 122                 *pgsize = PAGE_SIZE;
 123                 contig_ptes = CONT_PTES;
 124                 break;
 125         }
 126
 127         return contig_ptes;
 128 }
 129
 130 pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
 131 {
 132         int ncontig, i;
 133         size_t pgsize;
 134         pte_t orig_pte = __ptep_get(ptep);
 135
 136         if (!pte_present(orig_pte) || !pte_cont(orig_pte))
 137                 return orig_pte;
 138
 139         ncontig = num_contig_ptes(page_size(pte_page(orig_pte)), &pgsize);
 140         for (i = 0; i < ncontig; i++, ptep++) {
 141                 pte_t pte = __ptep_get(ptep);
 142
 143                 if (pte_dirty(pte))
 144                         orig_pte = pte_mkdirty(orig_pte);
 145
 146                 if (pte_young(pte))
 147                         orig_pte = pte_mkyoung(orig_pte);
 148         }
 149         return orig_pte;
 150 }
 151
 152 /*
 153  * Changing some bits of contiguous entries requires us to follow a
 154  * Break-Before-Make approach, breaking the whole contiguous set
 155  * before we can change any entries. See ARM DDI 0487A.k_iss10775,
 156  * "Misprogramming of the Contiguous bit", page D4-1762.
 157  *
 158  * This helper performs the break step.
 159  */
 160 static pte_t get_clear_contig(struct mm_struct *mm,
 161                              unsigned long addr,
 162                              pte_t *ptep,
 163                              unsigned long pgsize,
 164                              unsigned long ncontig)
 165 {
 166         pte_t orig_pte = __ptep_get(ptep);
 167         unsigned long i;
 168
 169         for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
 170                 pte_t pte = __ptep_get_and_clear(mm, addr, ptep);
 171
 172                 /*
 173                  * If HW_AFDBM is enabled, then the HW could turn on
 174                  * the dirty or accessed bit for any page in the set,
 175                  * so check them all.
 176                  */
 177                 if (pte_dirty(pte))
 178                         orig_pte = pte_mkdirty(orig_pte);
 179
 180                 if (pte_young(pte))
 181                         orig_pte = pte_mkyoung(orig_pte);
 182         }
 183         return orig_pte;
 184 }
 185
 186 static pte_t get_clear_contig_flush(struct mm_struct *mm,
 187                                     unsigned long addr,
 188                                     pte_t *ptep,
 189                                     unsigned long pgsize,
 190                                     unsigned long ncontig)
 191 {
 192         pte_t orig_pte = get_clear_contig(mm, addr, ptep, pgsize, ncontig);
 193         struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
 194
 195         flush_tlb_range(&vma, addr, addr + (pgsize * ncontig));
 196         return orig_pte;
 197 }
 198
 199 /*
 200  * Changing some bits of contiguous entries requires us to follow a
 201  * Break-Before-Make approach, breaking the whole contiguous set
 202  * before we can change any entries. See ARM DDI 0487A.k_iss10775,
 203  * "Misprogramming of the Contiguous bit", page D4-1762.
 204  *
 205  * This helper performs the break step for use cases where the
 206  * original pte is not needed.
 207  */
 208 static void clear_flush(struct mm_struct *mm,
 209                              unsigned long addr,
 210                              pte_t *ptep,
 211                              unsigned long pgsize,
 212                              unsigned long ncontig)
 213 {
 214         struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
 215         unsigned long i, saddr = addr;
 216
 217         for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
 218                 __ptep_get_and_clear(mm, addr, ptep);
 219
 220         flush_tlb_range(&vma, saddr, addr);
 221 }
 222
 223 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 224                             pte_t *ptep, pte_t pte, unsigned long sz)
 225 {
 226         size_t pgsize;
 227         int i;
 228         int ncontig;
 229         unsigned long pfn, dpfn;
 230         pgprot_t hugeprot;
 231
 232         ncontig = num_contig_ptes(sz, &pgsize);
 233
 234         if (!pte_present(pte)) {
 235                 for (i = 0; i < ncontig; i++, ptep++, addr += pgsize)
 236                         __set_ptes(mm, addr, ptep, pte, 1);
 237                 return;
 238         }
 239
 240         if (!pte_cont(pte)) {
 241                 __set_ptes(mm, addr, ptep, pte, 1);
 242                 return;
 243         }
 244
 245         pfn = pte_pfn(pte);
 246         dpfn = pgsize >> PAGE_SHIFT;
 247         hugeprot = pte_pgprot(pte);
 248
 249         clear_flush(mm, addr, ptep, pgsize, ncontig);
 250
 251         for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
 252                 __set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
 253 }
 254
 255 pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
 256                       unsigned long addr, unsigned long sz)
 257 {
 258         pgd_t *pgdp;
 259         p4d_t *p4dp;
 260         pud_t *pudp;
 261         pmd_t *pmdp;
 262         pte_t *ptep = NULL;
 263
 264         pgdp = pgd_offset(mm, addr);
 265         p4dp = p4d_alloc(mm, pgdp, addr);
 266         if (!p4dp)
 267                 return NULL;
 268
 269         pudp = pud_alloc(mm, p4dp, addr);
 270         if (!pudp)
 271                 return NULL;
 272
 273         if (sz == PUD_SIZE) {
 274                 ptep = (pte_t *)pudp;
 275         } else if (sz == (CONT_PTE_SIZE)) {
 276                 pmdp = pmd_alloc(mm, pudp, addr);
 277                 if (!pmdp)
 278                         return NULL;
 279
 280                 WARN_ON(addr & (sz - 1));
 281                 ptep = pte_alloc_huge(mm, pmdp, addr);
 282         } else if (sz == PMD_SIZE) {
 283                 if (want_pmd_share(vma, addr) && pud_none(READ_ONCE(*pudp)))
 284                         ptep = huge_pmd_share(mm, vma, addr, pudp);
 285                 else
 286                         ptep = (pte_t *)pmd_alloc(mm, pudp, addr);
 287         } else if (sz == (CONT_PMD_SIZE)) {
 288                 pmdp = pmd_alloc(mm, pudp, addr);
 289                 WARN_ON(addr & (sz - 1));
 290                 return (pte_t *)pmdp;
 291         }
 292
 293         return ptep;
 294 }
 295
 296 pte_t *huge_pte_offset(struct mm_struct *mm,
 297                        unsigned long addr, unsigned long sz)
 298 {
 299         pgd_t *pgdp;
 300         p4d_t *p4dp;
 301         pud_t *pudp, pud;
 302         pmd_t *pmdp, pmd;
 303
 304         pgdp = pgd_offset(mm, addr);
 305         if (!pgd_present(READ_ONCE(*pgdp)))
 306                 return NULL;
 307
 308         p4dp = p4d_offset(pgdp, addr);
 309         if (!p4d_present(READ_ONCE(*p4dp)))
 310                 return NULL;
 311
 312         pudp = pud_offset(p4dp, addr);
 313         pud = READ_ONCE(*pudp);
 314         if (sz != PUD_SIZE && pud_none(pud))
 315                 return NULL;
 316         /* hugepage or swap? */
 317         if (pud_leaf(pud) || !pud_present(pud))
 318                 return (pte_t *)pudp;
 319         /* table; check the next level */
 320
 321         if (sz == CONT_PMD_SIZE)
 322                 addr &= CONT_PMD_MASK;
 323
 324         pmdp = pmd_offset(pudp, addr);
 325         pmd = READ_ONCE(*pmdp);
 326         if (!(sz == PMD_SIZE || sz == CONT_PMD_SIZE) &&
 327             pmd_none(pmd))
 328                 return NULL;
 329         if (pmd_leaf(pmd) || !pmd_present(pmd))
 330                 return (pte_t *)pmdp;
 331
 332         if (sz == CONT_PTE_SIZE)
 333                 return pte_offset_huge(pmdp, (addr & CONT_PTE_MASK));
 334
 335         return NULL;
 336 }
 337
 338 unsigned long hugetlb_mask_last_page(struct hstate *h)
 339 {
 340         unsigned long hp_size = huge_page_size(h);
 341
 342         switch (hp_size) {
 343 #ifndef __PAGETABLE_PMD_FOLDED
 344         case PUD_SIZE:
 345                 return PGDIR_SIZE - PUD_SIZE;
 346 #endif
 347         case CONT_PMD_SIZE:
 348                 return PUD_SIZE - CONT_PMD_SIZE;
 349         case PMD_SIZE:
 350                 return PUD_SIZE - PMD_SIZE;
 351         case CONT_PTE_SIZE:
 352                 return PMD_SIZE - CONT_PTE_SIZE;
 353         default:
 354                 break;
 355         }
 356
 357         return 0UL;
 358 }
 359
 360 pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)
 361 {
 362         size_t pagesize = 1UL << shift;
 363
 364         entry = pte_mkhuge(entry);
 365         if (pagesize == CONT_PTE_SIZE) {
 366                 entry = pte_mkcont(entry);
 367         } else if (pagesize == CONT_PMD_SIZE) {
 368                 entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
 369         } else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) {
 370                 pr_warn("%s: unrecognized huge page size 0x%lx\n",
 371                         __func__, pagesize);
 372         }
 373         return entry;
 374 }
 375
 376 void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 377                     pte_t *ptep, unsigned long sz)
 378 {
 379         int i, ncontig;
 380         size_t pgsize;
 381
 382         ncontig = num_contig_ptes(sz, &pgsize);
 383
 384         for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
 385                 __pte_clear(mm, addr, ptep);
 386 }
 387
 388 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 389                               unsigned long addr, pte_t *ptep)
 390 {
 391         int ncontig;
 392         size_t pgsize;
 393         pte_t orig_pte = __ptep_get(ptep);
 394
 395         if (!pte_cont(orig_pte))
 396                 return __ptep_get_and_clear(mm, addr, ptep);
 397
 398         ncontig = find_num_contig(mm, addr, ptep, &pgsize);
 399
 400         return get_clear_contig(mm, addr, ptep, pgsize, ncontig);
 401 }
 402
 403 /*
 404  * huge_ptep_set_access_flags will update access flags (dirty, accesssed)
 405  * and write permission.
 406  *
 407  * For a contiguous huge pte range we need to check whether or not write
 408  * permission has to change only on the first pte in the set. Then for
 409  * all the contiguous ptes we need to check whether or not there is a
 410  * discrepancy between dirty or young.
 411  */
 412 static int __cont_access_flags_changed(pte_t *ptep, pte_t pte, int ncontig)
 413 {
 414         int i;
 415
 416         if (pte_write(pte) != pte_write(__ptep_get(ptep)))
 417                 return 1;
 418
 419         for (i = 0; i < ncontig; i++) {
 420                 pte_t orig_pte = __ptep_get(ptep + i);
 421
 422                 if (pte_dirty(pte) != pte_dirty(orig_pte))
 423                         return 1;
 424
 425                 if (pte_young(pte) != pte_young(orig_pte))
 426                         return 1;
 427         }
 428
 429         return 0;
 430 }
 431
 432 int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 433                                unsigned long addr, pte_t *ptep,
 434                                pte_t pte, int dirty)
 435 {
 436         int ncontig, i;
 437         size_t pgsize = 0;
 438         unsigned long pfn = pte_pfn(pte), dpfn;
 439         struct mm_struct *mm = vma->vm_mm;
 440         pgprot_t hugeprot;
 441         pte_t orig_pte;
 442
 443         if (!pte_cont(pte))
 444                 return __ptep_set_access_flags(vma, addr, ptep, pte, dirty);
 445
 446         ncontig = find_num_contig(mm, addr, ptep, &pgsize);
 447         dpfn = pgsize >> PAGE_SHIFT;
 448
 449         if (!__cont_access_flags_changed(ptep, pte, ncontig))
 450                 return 0;
 451
 452         orig_pte = get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig);
 453
 454         /* Make sure we don't lose the dirty or young state */
 455         if (pte_dirty(orig_pte))
 456                 pte = pte_mkdirty(pte);
 457
 458         if (pte_young(orig_pte))
 459                 pte = pte_mkyoung(pte);
 460
 461         hugeprot = pte_pgprot(pte);
 462         for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
 463                 __set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
 464
 465         return 1;
 466 }
 467
 468 void huge_ptep_set_wrprotect(struct mm_struct *mm,
 469                              unsigned long addr, pte_t *ptep)
 470 {
 471         unsigned long pfn, dpfn;
 472         pgprot_t hugeprot;
 473         int ncontig, i;
 474         size_t pgsize;
 475         pte_t pte;
 476
 477         if (!pte_cont(__ptep_get(ptep))) {
 478                 __ptep_set_wrprotect(mm, addr, ptep);
 479                 return;
 480         }
 481
 482         ncontig = find_num_contig(mm, addr, ptep, &pgsize);
 483         dpfn = pgsize >> PAGE_SHIFT;
 484
 485         pte = get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig);
 486         pte = pte_wrprotect(pte);
 487
 488         hugeprot = pte_pgprot(pte);
 489         pfn = pte_pfn(pte);
 490
 491         for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
 492                 __set_ptes(mm, addr, ptep, pfn_pte(pfn, hugeprot), 1);
 493 }
 494
 495 pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
 496                             unsigned long addr, pte_t *ptep)
 497 {
 498         struct mm_struct *mm = vma->vm_mm;
 499         size_t pgsize;
 500         int ncontig;
 501
 502         if (!pte_cont(__ptep_get(ptep)))
 503                 return ptep_clear_flush(vma, addr, ptep);
 504
 505         ncontig = find_num_contig(mm, addr, ptep, &pgsize);
 506         return get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig);
 507 }
 508
 509 static int __init hugetlbpage_init(void)
 510 {
 511         if (pud_sect_supported())
 512                 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
 513
 514         hugetlb_add_hstate(CONT_PMD_SHIFT - PAGE_SHIFT);
 515         hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
 516         hugetlb_add_hstate(CONT_PTE_SHIFT - PAGE_SHIFT);
 517
 518         return 0;
 519 }
 520 arch_initcall(hugetlbpage_init);
 521
 522 bool __init arch_hugetlb_valid_size(unsigned long size)
 523 {
 524         return __hugetlb_valid_size(size);
 525 }
 526
 527 pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
 528 {
 529         if (alternative_has_cap_unlikely(ARM64_WORKAROUND_2645198)) {
 530                 /*
 531                  * Break-before-make (BBM) is required for all user space mappings
 532                  * when the permission changes from executable to non-executable
 533                  * in cases where cpu is affected with errata #2645198.
 534                  */
 535                 if (pte_user_exec(__ptep_get(ptep)))
 536                         return huge_ptep_clear_flush(vma, addr, ptep);
 537         }
 538         return huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
 539 }
 540
 541 void huge_ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep,
 542                                   pte_t old_pte, pte_t pte)
 543 {
 544         unsigned long psize = huge_page_size(hstate_vma(vma));
 545
 546         set_huge_pte_at(vma->vm_mm, addr, ptep, pte, psize);
 547 }