arch/arm64/mm/hugetlbpage.c

   1 /*
   2  * arch/arm64/mm/hugetlbpage.c
   3  *
   4  * Copyright (C) 2013 Linaro Ltd.
   5  *
   6  * Based on arch/x86/mm/hugetlbpage.c.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  */
  17
  18 #include <linux/init.h>
  19 #include <linux/fs.h>
  20 #include <linux/mm.h>
  21 #include <linux/hugetlb.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/err.h>
  24 #include <linux/sysctl.h>
  25 #include <asm/mman.h>
  26 #include <asm/tlb.h>
  27 #include <asm/tlbflush.h>
  28 #include <asm/pgalloc.h>
  29
  30 int pmd_huge(pmd_t pmd)
  31 {
  32         return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
  33 }
  34
  35 int pud_huge(pud_t pud)
  36 {
  37 #ifndef __PAGETABLE_PMD_FOLDED
  38         return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
  39 #else
  40         return 0;
  41 #endif
  42 }
  43
  44 /*
  45  * Select all bits except the pfn
  46  */
  47 static inline pgprot_t pte_pgprot(pte_t pte)
  48 {
  49         unsigned long pfn = pte_pfn(pte);
  50
  51         return __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^ pte_val(pte));
  52 }
  53
  54 static int find_num_contig(struct mm_struct *mm, unsigned long addr,
  55                            pte_t *ptep, size_t *pgsize)
  56 {
  57         pgd_t *pgdp = pgd_offset(mm, addr);
  58         pud_t *pudp;
  59         pmd_t *pmdp;
  60
  61         *pgsize = PAGE_SIZE;
  62         pudp = pud_offset(pgdp, addr);
  63         pmdp = pmd_offset(pudp, addr);
  64         if ((pte_t *)pmdp == ptep) {
  65                 *pgsize = PMD_SIZE;
  66                 return CONT_PMDS;
  67         }
  68         return CONT_PTES;
  69 }
  70
  71 static inline int num_contig_ptes(unsigned long size, size_t *pgsize)
  72 {
  73         int contig_ptes = 0;
  74
  75         *pgsize = size;
  76
  77         switch (size) {
  78 #ifdef CONFIG_ARM64_4K_PAGES
  79         case PUD_SIZE:
  80 #endif
  81         case PMD_SIZE:
  82                 contig_ptes = 1;
  83                 break;
  84         case CONT_PMD_SIZE:
  85                 *pgsize = PMD_SIZE;
  86                 contig_ptes = CONT_PMDS;
  87                 break;
  88         case CONT_PTE_SIZE:
  89                 *pgsize = PAGE_SIZE;
  90                 contig_ptes = CONT_PTES;
  91                 break;
  92         }
  93
  94         return contig_ptes;
  95 }
  96
  97 /*
  98  * Changing some bits of contiguous entries requires us to follow a
  99  * Break-Before-Make approach, breaking the whole contiguous set
 100  * before we can change any entries. See ARM DDI 0487A.k_iss10775,
 101  * "Misprogramming of the Contiguous bit", page D4-1762.
 102  *
 103  * This helper performs the break step.
 104  */
 105 static pte_t get_clear_flush(struct mm_struct *mm,
 106                              unsigned long addr,
 107                              pte_t *ptep,
 108                              unsigned long pgsize,
 109                              unsigned long ncontig)
 110 {
 111         struct vm_area_struct vma = { .vm_mm = mm };
 112         pte_t orig_pte = huge_ptep_get(ptep);
 113         bool valid = pte_valid(orig_pte);
 114         unsigned long i, saddr = addr;
 115
 116         for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
 117                 pte_t pte = ptep_get_and_clear(mm, addr, ptep);
 118
 119                 /*
 120                  * If HW_AFDBM is enabled, then the HW could turn on
 121                  * the dirty bit for any page in the set, so check
 122                  * them all.  All hugetlb entries are already young.
 123                  */
 124                 if (pte_dirty(pte))
 125                         orig_pte = pte_mkdirty(orig_pte);
 126         }
 127
 128         if (valid)
 129                 flush_tlb_range(&vma, saddr, addr);
 130         return orig_pte;
 131 }
 132
 133 /*
 134  * Changing some bits of contiguous entries requires us to follow a
 135  * Break-Before-Make approach, breaking the whole contiguous set
 136  * before we can change any entries. See ARM DDI 0487A.k_iss10775,
 137  * "Misprogramming of the Contiguous bit", page D4-1762.
 138  *
 139  * This helper performs the break step for use cases where the
 140  * original pte is not needed.
 141  */
 142 static void clear_flush(struct mm_struct *mm,
 143                              unsigned long addr,
 144                              pte_t *ptep,
 145                              unsigned long pgsize,
 146                              unsigned long ncontig)
 147 {
 148         struct vm_area_struct vma = { .vm_mm = mm };
 149         unsigned long i, saddr = addr;
 150
 151         for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
 152                 pte_clear(mm, addr, ptep);
 153
 154         flush_tlb_range(&vma, saddr, addr);
 155 }
 156
 157 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 158                             pte_t *ptep, pte_t pte)
 159 {
 160         size_t pgsize;
 161         int i;
 162         int ncontig;
 163         unsigned long pfn, dpfn;
 164         pgprot_t hugeprot;
 165
 166         /*
 167          * Code needs to be expanded to handle huge swap and migration
 168          * entries. Needed for HUGETLB and MEMORY_FAILURE.
 169          */
 170         WARN_ON(!pte_present(pte));
 171
 172         if (!pte_cont(pte)) {
 173                 set_pte_at(mm, addr, ptep, pte);
 174                 return;
 175         }
 176
 177         ncontig = find_num_contig(mm, addr, ptep, &pgsize);
 178         pfn = pte_pfn(pte);
 179         dpfn = pgsize >> PAGE_SHIFT;
 180         hugeprot = pte_pgprot(pte);
 181
 182         clear_flush(mm, addr, ptep, pgsize, ncontig);
 183
 184         for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
 185                 set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
 186 }
 187
 188 void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
 189                           pte_t *ptep, pte_t pte, unsigned long sz)
 190 {
 191         int i, ncontig;
 192         size_t pgsize;
 193
 194         ncontig = num_contig_ptes(sz, &pgsize);
 195
 196         for (i = 0; i < ncontig; i++, ptep++)
 197                 set_pte(ptep, pte);
 198 }
 199
 200 pte_t *huge_pte_alloc(struct mm_struct *mm,
 201                       unsigned long addr, unsigned long sz)
 202 {
 203         pgd_t *pgdp;
 204         pud_t *pudp;
 205         pmd_t *pmdp;
 206         pte_t *ptep = NULL;
 207
 208         pgdp = pgd_offset(mm, addr);
 209         pudp = pud_alloc(mm, pgdp, addr);
 210         if (!pudp)
 211                 return NULL;
 212
 213         if (sz == PUD_SIZE) {
 214                 ptep = (pte_t *)pudp;
 215         } else if (sz == (PAGE_SIZE * CONT_PTES)) {
 216                 pmdp = pmd_alloc(mm, pudp, addr);
 217
 218                 WARN_ON(addr & (sz - 1));
 219                 /*
 220                  * Note that if this code were ever ported to the
 221                  * 32-bit arm platform then it will cause trouble in
 222                  * the case where CONFIG_HIGHPTE is set, since there
 223                  * will be no pte_unmap() to correspond with this
 224                  * pte_alloc_map().
 225                  */
 226                 ptep = pte_alloc_map(mm, pmdp, addr);
 227         } else if (sz == PMD_SIZE) {
 228                 if (IS_ENABLED(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) &&
 229                     pud_none(READ_ONCE(*pudp)))
 230                         ptep = huge_pmd_share(mm, addr, pudp);
 231                 else
 232                         ptep = (pte_t *)pmd_alloc(mm, pudp, addr);
 233         } else if (sz == (PMD_SIZE * CONT_PMDS)) {
 234                 pmdp = pmd_alloc(mm, pudp, addr);
 235                 WARN_ON(addr & (sz - 1));
 236                 return (pte_t *)pmdp;
 237         }
 238
 239         return ptep;
 240 }
 241
 242 pte_t *huge_pte_offset(struct mm_struct *mm,
 243                        unsigned long addr, unsigned long sz)
 244 {
 245         pgd_t *pgdp;
 246         pud_t *pudp, pud;
 247         pmd_t *pmdp, pmd;
 248
 249         pgdp = pgd_offset(mm, addr);
 250         if (!pgd_present(READ_ONCE(*pgdp)))
 251                 return NULL;
 252
 253         pudp = pud_offset(pgdp, addr);
 254         pud = READ_ONCE(*pudp);
 255         if (sz != PUD_SIZE && pud_none(pud))
 256                 return NULL;
 257         /* hugepage or swap? */
 258         if (pud_huge(pud) || !pud_present(pud))
 259                 return (pte_t *)pudp;
 260         /* table; check the next level */
 261
 262         if (sz == CONT_PMD_SIZE)
 263                 addr &= CONT_PMD_MASK;
 264
 265         pmdp = pmd_offset(pudp, addr);
 266         pmd = READ_ONCE(*pmdp);
 267         if (!(sz == PMD_SIZE || sz == CONT_PMD_SIZE) &&
 268             pmd_none(pmd))
 269                 return NULL;
 270         if (pmd_huge(pmd) || !pmd_present(pmd))
 271                 return (pte_t *)pmdp;
 272
 273         if (sz == CONT_PTE_SIZE)
 274                 return pte_offset_kernel(pmdp, (addr & CONT_PTE_MASK));
 275
 276         return NULL;
 277 }
 278
 279 pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
 280                          struct page *page, int writable)
 281 {
 282         size_t pagesize = huge_page_size(hstate_vma(vma));
 283
 284         if (pagesize == CONT_PTE_SIZE) {
 285                 entry = pte_mkcont(entry);
 286         } else if (pagesize == CONT_PMD_SIZE) {
 287                 entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
 288         } else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) {
 289                 pr_warn("%s: unrecognized huge page size 0x%lx\n",
 290                         __func__, pagesize);
 291         }
 292         return entry;
 293 }
 294
 295 void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
 296                     pte_t *ptep, unsigned long sz)
 297 {
 298         int i, ncontig;
 299         size_t pgsize;
 300
 301         ncontig = num_contig_ptes(sz, &pgsize);
 302
 303         for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
 304                 pte_clear(mm, addr, ptep);
 305 }
 306
 307 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 308                               unsigned long addr, pte_t *ptep)
 309 {
 310         int ncontig;
 311         size_t pgsize;
 312         pte_t orig_pte = huge_ptep_get(ptep);
 313
 314         if (!pte_cont(orig_pte))
 315                 return ptep_get_and_clear(mm, addr, ptep);
 316
 317         ncontig = find_num_contig(mm, addr, ptep, &pgsize);
 318
 319         return get_clear_flush(mm, addr, ptep, pgsize, ncontig);
 320 }
 321
 322 int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 323                                unsigned long addr, pte_t *ptep,
 324                                pte_t pte, int dirty)
 325 {
 326         int ncontig, i, changed = 0;
 327         size_t pgsize = 0;
 328         unsigned long pfn = pte_pfn(pte), dpfn;
 329         pgprot_t hugeprot;
 330         pte_t orig_pte;
 331
 332         if (!pte_cont(pte))
 333                 return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
 334
 335         ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
 336         dpfn = pgsize >> PAGE_SHIFT;
 337
 338         orig_pte = get_clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
 339         if (!pte_same(orig_pte, pte))
 340                 changed = 1;
 341
 342         /* Make sure we don't lose the dirty state */
 343         if (pte_dirty(orig_pte))
 344                 pte = pte_mkdirty(pte);
 345
 346         hugeprot = pte_pgprot(pte);
 347         for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
 348                 set_pte_at(vma->vm_mm, addr, ptep, pfn_pte(pfn, hugeprot));
 349
 350         return changed;
 351 }
 352
 353 void huge_ptep_set_wrprotect(struct mm_struct *mm,
 354                              unsigned long addr, pte_t *ptep)
 355 {
 356         unsigned long pfn, dpfn;
 357         pgprot_t hugeprot;
 358         int ncontig, i;
 359         size_t pgsize;
 360         pte_t pte;
 361
 362         if (!pte_cont(READ_ONCE(*ptep))) {
 363                 ptep_set_wrprotect(mm, addr, ptep);
 364                 return;
 365         }
 366
 367         ncontig = find_num_contig(mm, addr, ptep, &pgsize);
 368         dpfn = pgsize >> PAGE_SHIFT;
 369
 370         pte = get_clear_flush(mm, addr, ptep, pgsize, ncontig);
 371         pte = pte_wrprotect(pte);
 372
 373         hugeprot = pte_pgprot(pte);
 374         pfn = pte_pfn(pte);
 375
 376         for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
 377                 set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
 378 }
 379
 380 void huge_ptep_clear_flush(struct vm_area_struct *vma,
 381                            unsigned long addr, pte_t *ptep)
 382 {
 383         size_t pgsize;
 384         int ncontig;
 385
 386         if (!pte_cont(READ_ONCE(*ptep))) {
 387                 ptep_clear_flush(vma, addr, ptep);
 388                 return;
 389         }
 390
 391         ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
 392         clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
 393 }
 394
 395 static __init int setup_hugepagesz(char *opt)
 396 {
 397         unsigned long ps = memparse(opt, &opt);
 398
 399         switch (ps) {
 400 #ifdef CONFIG_ARM64_4K_PAGES
 401         case PUD_SIZE:
 402 #endif
 403         case PMD_SIZE * CONT_PMDS:
 404         case PMD_SIZE:
 405         case PAGE_SIZE * CONT_PTES:
 406                 hugetlb_add_hstate(ilog2(ps) - PAGE_SHIFT);
 407                 return 1;
 408         }
 409
 410         hugetlb_bad_size();
 411         pr_err("hugepagesz: Unsupported page size %lu K\n", ps >> 10);
 412         return 0;
 413 }
 414 __setup("hugepagesz=", setup_hugepagesz);
 415
 416 #ifdef CONFIG_ARM64_64K_PAGES
 417 static __init int add_default_hugepagesz(void)
 418 {
 419         if (size_to_hstate(CONT_PTES * PAGE_SIZE) == NULL)
 420                 hugetlb_add_hstate(CONT_PTE_SHIFT);
 421         return 0;
 422 }
 423 arch_initcall(add_default_hugepagesz);
 424 #endif