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         if (!pgd_present(*pgd)) {
  55                 VM_BUG_ON(!pgd_present(*pgd));
  56                 return 1;
  57         }
  58         pud = pud_offset(pgd, addr);
  59         if (!pud_present(*pud)) {
  60                 VM_BUG_ON(!pud_present(*pud));
  61                 return 1;
  62         }
  63         pmd = pmd_offset(pud, addr);
  64         if (!pmd_present(*pmd)) {
  65                 VM_BUG_ON(!pmd_present(*pmd));
  66                 return 1;
  67         }
  68         if ((pte_t *)pmd == ptep) {
  69                 *pgsize = PMD_SIZE;
  70                 return CONT_PMDS;
  71         }
  72         return CONT_PTES;
  73 }
  74
  75 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
  76                             pte_t *ptep, pte_t pte)
  77 {
  78         size_t pgsize;
  79         int i;
  80         int ncontig = find_num_contig(mm, addr, ptep, pte, &pgsize);
  81         unsigned long pfn;
  82         pgprot_t hugeprot;
  83
  84         if (ncontig == 1) {
  85                 set_pte_at(mm, addr, ptep, pte);
  86                 return;
  87         }
  88
  89         pfn = pte_pfn(pte);
  90         hugeprot = __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^ pte_val(pte));
  91         for (i = 0; i < ncontig; i++) {
  92                 pr_debug("%s: set pte %p to 0x%llx\n", __func__, ptep,
  93                          pte_val(pfn_pte(pfn, hugeprot)));
  94                 set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
  95                 ptep++;
  96                 pfn += pgsize >> PAGE_SHIFT;
  97                 addr += pgsize;
  98         }
  99 }
 100
 101 pte_t *huge_pte_alloc(struct mm_struct *mm,
 102                       unsigned long addr, unsigned long sz)
 103 {
 104         pgd_t *pgd;
 105         pud_t *pud;
 106         pte_t *pte = NULL;
 107
 108         pr_debug("%s: addr:0x%lx sz:0x%lx\n", __func__, addr, sz);
 109         pgd = pgd_offset(mm, addr);
 110         pud = pud_alloc(mm, pgd, addr);
 111         if (!pud)
 112                 return NULL;
 113
 114         if (sz == PUD_SIZE) {
 115                 pte = (pte_t *)pud;
 116         } else if (sz == (PAGE_SIZE * CONT_PTES)) {
 117                 pmd_t *pmd = pmd_alloc(mm, pud, addr);
 118
 119                 WARN_ON(addr & (sz - 1));
 120                 /*
 121                  * Note that if this code were ever ported to the
 122                  * 32-bit arm platform then it will cause trouble in
 123                  * the case where CONFIG_HIGHPTE is set, since there
 124                  * will be no pte_unmap() to correspond with this
 125                  * pte_alloc_map().
 126                  */
 127                 pte = pte_alloc_map(mm, pmd, addr);
 128         } else if (sz == PMD_SIZE) {
 129                 if (IS_ENABLED(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) &&
 130                     pud_none(*pud))
 131                         pte = huge_pmd_share(mm, addr, pud);
 132                 else
 133                         pte = (pte_t *)pmd_alloc(mm, pud, addr);
 134         } else if (sz == (PMD_SIZE * CONT_PMDS)) {
 135                 pmd_t *pmd;
 136
 137                 pmd = pmd_alloc(mm, pud, addr);
 138                 WARN_ON(addr & (sz - 1));
 139                 return (pte_t *)pmd;
 140         }
 141
 142         pr_debug("%s: addr:0x%lx sz:0x%lx ret pte=%p/0x%llx\n", __func__, addr,
 143                sz, pte, pte_val(*pte));
 144         return pte;
 145 }
 146
 147 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
 148 {
 149         pgd_t *pgd;
 150         pud_t *pud;
 151         pmd_t *pmd = NULL;
 152         pte_t *pte = NULL;
 153
 154         pgd = pgd_offset(mm, addr);
 155         pr_debug("%s: addr:0x%lx pgd:%p\n", __func__, addr, pgd);
 156         if (!pgd_present(*pgd))
 157                 return NULL;
 158         pud = pud_offset(pgd, addr);
 159         if (!pud_present(*pud))
 160                 return NULL;
 161
 162         if (pud_huge(*pud))
 163                 return (pte_t *)pud;
 164         pmd = pmd_offset(pud, addr);
 165         if (!pmd_present(*pmd))
 166                 return NULL;
 167
 168         if (pte_cont(pmd_pte(*pmd))) {
 169                 pmd = pmd_offset(
 170                         pud, (addr & CONT_PMD_MASK));
 171                 return (pte_t *)pmd;
 172         }
 173         if (pmd_huge(*pmd))
 174                 return (pte_t *)pmd;
 175         pte = pte_offset_kernel(pmd, addr);
 176         if (pte_present(*pte) && pte_cont(*pte)) {
 177                 pte = pte_offset_kernel(
 178                         pmd, (addr & CONT_PTE_MASK));
 179                 return pte;
 180         }
 181         return NULL;
 182 }
 183
 184 pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
 185                          struct page *page, int writable)
 186 {
 187         size_t pagesize = huge_page_size(hstate_vma(vma));
 188
 189         if (pagesize == CONT_PTE_SIZE) {
 190                 entry = pte_mkcont(entry);
 191         } else if (pagesize == CONT_PMD_SIZE) {
 192                 entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
 193         } else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) {
 194                 pr_warn("%s: unrecognized huge page size 0x%lx\n",
 195                         __func__, pagesize);
 196         }
 197         return entry;
 198 }
 199
 200 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
 201                               unsigned long addr, pte_t *ptep)
 202 {
 203         pte_t pte;
 204
 205         if (pte_cont(*ptep)) {
 206                 int ncontig, i;
 207                 size_t pgsize;
 208                 pte_t *cpte;
 209                 bool is_dirty = false;
 210
 211                 cpte = huge_pte_offset(mm, addr);
 212                 ncontig = find_num_contig(mm, addr, cpte, *cpte, &pgsize);
 213                 /* save the 1st pte to return */
 214                 pte = ptep_get_and_clear(mm, addr, cpte);
 215                 for (i = 1; i < ncontig; ++i) {
 216                         /*
 217                          * If HW_AFDBM is enabled, then the HW could
 218                          * turn on the dirty bit for any of the page
 219                          * in the set, so check them all.
 220                          */
 221                         ++cpte;
 222                         if (pte_dirty(ptep_get_and_clear(mm, addr, cpte)))
 223                                 is_dirty = true;
 224                 }
 225                 if (is_dirty)
 226                         return pte_mkdirty(pte);
 227                 else
 228                         return pte;
 229         } else {
 230                 return ptep_get_and_clear(mm, addr, ptep);
 231         }
 232 }
 233
 234 int huge_ptep_set_access_flags(struct vm_area_struct *vma,
 235                                unsigned long addr, pte_t *ptep,
 236                                pte_t pte, int dirty)
 237 {
 238         pte_t *cpte;
 239
 240         if (pte_cont(pte)) {
 241                 int ncontig, i, changed = 0;
 242                 size_t pgsize = 0;
 243                 unsigned long pfn = pte_pfn(pte);
 244                 /* Select all bits except the pfn */
 245                 pgprot_t hugeprot =
 246                         __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^
 247                                  pte_val(pte));
 248
 249                 cpte = huge_pte_offset(vma->vm_mm, addr);
 250                 pfn = pte_pfn(*cpte);
 251                 ncontig = find_num_contig(vma->vm_mm, addr, cpte,
 252                                           *cpte, &pgsize);
 253                 for (i = 0; i < ncontig; ++i, ++cpte) {
 254                         changed = ptep_set_access_flags(vma, addr, cpte,
 255                                                         pfn_pte(pfn,
 256                                                                 hugeprot),
 257                                                         dirty);
 258                         pfn += pgsize >> PAGE_SHIFT;
 259                 }
 260                 return changed;
 261         } else {
 262                 return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
 263         }
 264 }
 265
 266 void huge_ptep_set_wrprotect(struct mm_struct *mm,
 267                              unsigned long addr, pte_t *ptep)
 268 {
 269         if (pte_cont(*ptep)) {
 270                 int ncontig, i;
 271                 pte_t *cpte;
 272                 size_t pgsize = 0;
 273
 274                 cpte = huge_pte_offset(mm, addr);
 275                 ncontig = find_num_contig(mm, addr, cpte, *cpte, &pgsize);
 276                 for (i = 0; i < ncontig; ++i, ++cpte)
 277                         ptep_set_wrprotect(mm, addr, cpte);
 278         } else {
 279                 ptep_set_wrprotect(mm, addr, ptep);
 280         }
 281 }
 282
 283 void huge_ptep_clear_flush(struct vm_area_struct *vma,
 284                            unsigned long addr, pte_t *ptep)
 285 {
 286         if (pte_cont(*ptep)) {
 287                 int ncontig, i;
 288                 pte_t *cpte;
 289                 size_t pgsize = 0;
 290
 291                 cpte = huge_pte_offset(vma->vm_mm, addr);
 292                 ncontig = find_num_contig(vma->vm_mm, addr, cpte,
 293                                           *cpte, &pgsize);
 294                 for (i = 0; i < ncontig; ++i, ++cpte)
 295                         ptep_clear_flush(vma, addr, cpte);
 296         } else {
 297                 ptep_clear_flush(vma, addr, ptep);
 298         }
 299 }
 300
 301 static __init int setup_hugepagesz(char *opt)
 302 {
 303         unsigned long ps = memparse(opt, &opt);
 304
 305         if (ps == PMD_SIZE) {
 306                 hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
 307         } else if (ps == PUD_SIZE) {
 308                 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
 309         } else if (ps == (PAGE_SIZE * CONT_PTES)) {
 310                 hugetlb_add_hstate(CONT_PTE_SHIFT);
 311         } else if (ps == (PMD_SIZE * CONT_PMDS)) {
 312                 hugetlb_add_hstate((PMD_SHIFT + CONT_PMD_SHIFT) - PAGE_SHIFT);
 313         } else {
 314                 hugetlb_bad_size();
 315                 pr_err("hugepagesz: Unsupported page size %lu K\n", ps >> 10);
 316                 return 0;
 317         }
 318         return 1;
 319 }
 320 __setup("hugepagesz=", setup_hugepagesz);
 321
 322 #ifdef CONFIG_ARM64_64K_PAGES
 323 static __init int add_default_hugepagesz(void)
 324 {
 325         if (size_to_hstate(CONT_PTES * PAGE_SIZE) == NULL)
 326                 hugetlb_add_hstate(CONT_PMD_SHIFT);
 327         return 0;
 328 }
 329 arch_initcall(add_default_hugepagesz);
 330 #endif