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 static int find_num_contig(struct mm_struct *mm, unsigned long addr,
  45                            pte_t *ptep, pte_t pte, size_t *pgsize)
  46 {
  47         pgd_t *pgd = pgd_offset(mm, addr);
  48         pud_t *pud;
  49         pmd_t *pmd;
  50
  51         *pgsize = PAGE_SIZE;
  52         if (!pte_cont(pte))
  53                 return 1;
  54         pud = pud_offset(pgd, addr);
  55         pmd = pmd_offset(pud, addr);
  56         if ((pte_t *)pmd == ptep) {
  57                 *pgsize = PMD_SIZE;
  58                 return CONT_PMDS;
  59         }
  60         return CONT_PTES;
  61 }
  62
  63 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
  64                             pte_t *ptep, pte_t pte)
  65 {
  66         size_t pgsize;
  67         int i;
  68         int ncontig = find_num_contig(mm, addr, ptep, pte, &pgsize);
  69         unsigned long pfn;
  70         pgprot_t hugeprot;
  71
  72         if (ncontig == 1) {
  73                 set_pte_at(mm, addr, ptep, pte);
  74                 return;
  75         }
  76
  77         pfn = pte_pfn(pte);
  78         hugeprot = __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^ pte_val(pte));
  79         for (i = 0; i < ncontig; i++) {
  80                 pr_debug("%s: set pte %p to 0x%llx\n", __func__, ptep,
  81                          pte_val(pfn_pte(pfn, hugeprot)));
  82                 set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
  83                 ptep++;
  84                 pfn += pgsize >> PAGE_SHIFT;
  85                 addr += pgsize;
  86         }
  87 }
  88
  89 pte_t *huge_pte_alloc(struct mm_struct *mm,
  90                       unsigned long addr, unsigned long sz)
  91 {
  92         pgd_t *pgd;
  93         pud_t *pud;
  94         pte_t *pte = NULL;
  95
  96         pr_debug("%s: addr:0x%lx sz:0x%lx\n", __func__, addr, sz);
  97         pgd = pgd_offset(mm, addr);
  98         pud = pud_alloc(mm, pgd, addr);
  99         if (!pud)
 100                 return NULL;
 101
 102         if (sz == PUD_SIZE) {
 103                 pte = (pte_t *)pud;
 104         } else if (sz == (PAGE_SIZE * CONT_PTES)) {
 105                 pmd_t *pmd = pmd_alloc(mm, pud, addr);
 106
 107                 WARN_ON(addr & (sz - 1));
 108                 /*
 109                  * Note that if this code were ever ported to the
 110                  * 32-bit arm platform then it will cause trouble in
 111                  * the case where CONFIG_HIGHPTE is set, since there
 112                  * will be no pte_unmap() to correspond with this
 113                  * pte_alloc_map().
 114                  */
 115                 pte = pte_alloc_map(mm, pmd, addr);
 116         } else if (sz == PMD_SIZE) {
 117                 if (IS_ENABLED(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) &&
 118                     pud_none(*pud))
 119                         pte = huge_pmd_share(mm, addr, pud);
 120                 else
 121                         pte = (pte_t *)pmd_alloc(mm, pud, addr);
 122         } else if (sz == (PMD_SIZE * CONT_PMDS)) {
 123                 pmd_t *pmd;
 124
 125                 pmd = pmd_alloc(mm, pud, addr);
 126                 WARN_ON(addr & (sz - 1));
 127                 return (pte_t *)pmd;
 128         }
 129
 130         pr_debug("%s: addr:0x%lx sz:0x%lx ret pte=%p/0x%llx\n", __func__, addr,
 131                sz, pte, pte_val(*pte));
 132         return pte;
 133 }
 134
 135 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
 136 {
 137         pgd_t *pgd;
 138         pud_t *pud;
 139         pmd_t *pmd = NULL;
 140         pte_t *pte = NULL;
 141
 142         pgd = pgd_offset(mm, addr);
 143         pr_debug("%s: addr:0x%lx pgd:%p\n", __func__, addr, pgd);
 144         if (!pgd_present(*pgd))
 145                 return NULL;
 146         pud = pud_offset(pgd, addr);
 147         if (!pud_present(*pud))
 148                 return NULL;
 149
 150         if (pud_huge(*pud))
 151                 return (pte_t *)pud;
 152         pmd = pmd_offset(pud, addr);
 153         if (!pmd_present(*pmd))
 154                 return NULL;
 155
 156         if (pte_cont(pmd_pte(*pmd))) {
 157                 pmd = pmd_offset(
 158                         pud, (addr & CONT_PMD_MASK));
 159                 return (pte_t *)pmd;
 160         }
 161         if (pmd_huge(*pmd))
 162                 return (pte_t *)pmd;
 163         pte = pte_offset_kernel(pmd, addr);
 164         if (pte_present(*pte) && pte_cont(*pte)) {
 165                 pte = pte_offset_kernel(
 166                         pmd, (addr & CONT_PTE_MASK));
 167                 return pte;
 168         }
 169         return NULL;
 170 }
 171
 172 pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
 173                          struct page *page, int writable)
 174 {
 175         size_t pagesize = huge_page_size(hstate_vma(vma));
 176
 177         if (pagesize == CONT_PTE_SIZE) {
 178                 entry = pte_mkcont(entry);
 179         } else if (pagesize == CONT_PMD_SIZE) {
 180                 entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
 181         } else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) {
 182                 pr_warn("%s: unrecognized huge page size 0x%lx\n",
 183                         __func__, pagesize);
 184         }
 185         return entry;
 186 }
 187
 188 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 189                               unsigned long addr, pte_t *ptep)
 190 {
 191         pte_t pte;
 192
 193         if (pte_cont(*ptep)) {
 194                 int ncontig, i;
 195                 size_t pgsize;
 196                 pte_t *cpte;
 197                 bool is_dirty = false;
 198
 199                 cpte = huge_pte_offset(mm, addr);
 200                 ncontig = find_num_contig(mm, addr, cpte, *cpte, &pgsize);
 201                 /* save the 1st pte to return */
 202                 pte = ptep_get_and_clear(mm, addr, cpte);
 203                 for (i = 1, addr += pgsize; i < ncontig; ++i, addr += pgsize) {
 204                         /*
 205                          * If HW_AFDBM is enabled, then the HW could
 206                          * turn on the dirty bit for any of the page
 207                          * in the set, so check them all.
 208                          */
 209                         ++cpte;
 210                         if (pte_dirty(ptep_get_and_clear(mm, addr, cpte)))
 211                                 is_dirty = true;
 212                 }
 213                 if (is_dirty)
 214                         return pte_mkdirty(pte);
 215                 else
 216                         return pte;
 217         } else {
 218                 return ptep_get_and_clear(mm, addr, ptep);
 219         }
 220 }
 221
 222 int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 223                                unsigned long addr, pte_t *ptep,
 224                                pte_t pte, int dirty)
 225 {
 226         pte_t *cpte;
 227
 228         if (pte_cont(pte)) {
 229                 int ncontig, i, changed = 0;
 230                 size_t pgsize = 0;
 231                 unsigned long pfn = pte_pfn(pte);
 232                 /* Select all bits except the pfn */
 233                 pgprot_t hugeprot =
 234                         __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^
 235                                  pte_val(pte));
 236
 237                 cpte = huge_pte_offset(vma->vm_mm, addr);
 238                 pfn = pte_pfn(*cpte);
 239                 ncontig = find_num_contig(vma->vm_mm, addr, cpte,
 240                                           *cpte, &pgsize);
 241                 for (i = 0; i < ncontig; ++i, ++cpte, addr += pgsize) {
 242                         changed |= ptep_set_access_flags(vma, addr, cpte,
 243                                                         pfn_pte(pfn,
 244                                                                 hugeprot),
 245                                                         dirty);
 246                         pfn += pgsize >> PAGE_SHIFT;
 247                 }
 248                 return changed;
 249         } else {
 250                 return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
 251         }
 252 }
 253
 254 void huge_ptep_set_wrprotect(struct mm_struct *mm,
 255                              unsigned long addr, pte_t *ptep)
 256 {
 257         if (pte_cont(*ptep)) {
 258                 int ncontig, i;
 259                 pte_t *cpte;
 260                 size_t pgsize = 0;
 261
 262                 cpte = huge_pte_offset(mm, addr);
 263                 ncontig = find_num_contig(mm, addr, cpte, *cpte, &pgsize);
 264                 for (i = 0; i < ncontig; ++i, ++cpte, addr += pgsize)
 265                         ptep_set_wrprotect(mm, addr, cpte);
 266         } else {
 267                 ptep_set_wrprotect(mm, addr, ptep);
 268         }
 269 }
 270
 271 void huge_ptep_clear_flush(struct vm_area_struct *vma,
 272                            unsigned long addr, pte_t *ptep)
 273 {
 274         if (pte_cont(*ptep)) {
 275                 int ncontig, i;
 276                 pte_t *cpte;
 277                 size_t pgsize = 0;
 278
 279                 cpte = huge_pte_offset(vma->vm_mm, addr);
 280                 ncontig = find_num_contig(vma->vm_mm, addr, cpte,
 281                                           *cpte, &pgsize);
 282                 for (i = 0; i < ncontig; ++i, ++cpte, addr += pgsize)
 283                         ptep_clear_flush(vma, addr, cpte);
 284         } else {
 285                 ptep_clear_flush(vma, addr, ptep);
 286         }
 287 }
 288
 289 static __init int setup_hugepagesz(char *opt)
 290 {
 291         unsigned long ps = memparse(opt, &opt);
 292
 293         if (ps == PMD_SIZE) {
 294                 hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
 295         } else if (ps == PUD_SIZE) {
 296                 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
 297         } else if (ps == (PAGE_SIZE * CONT_PTES)) {
 298                 hugetlb_add_hstate(CONT_PTE_SHIFT);
 299         } else if (ps == (PMD_SIZE * CONT_PMDS)) {
 300                 hugetlb_add_hstate((PMD_SHIFT + CONT_PMD_SHIFT) - PAGE_SHIFT);
 301         } else {
 302                 hugetlb_bad_size();
 303                 pr_err("hugepagesz: Unsupported page size %lu K\n", ps >> 10);
 304                 return 0;
 305         }
 306         return 1;
 307 }
 308 __setup("hugepagesz=", setup_hugepagesz);
 309
 310 #ifdef CONFIG_ARM64_64K_PAGES
 311 static __init int add_default_hugepagesz(void)
 312 {
 313         if (size_to_hstate(CONT_PTES * PAGE_SIZE) == NULL)
 314                 hugetlb_add_hstate(CONT_PMD_SHIFT);
 315         return 0;
 316 }
 317 arch_initcall(add_default_hugepagesz);
 318 #endif