mm/pagewalk.c

   1 #include <linux/mm.h>
   2 #include <linux/highmem.h>
   3 #include <linux/sched.h>
   4 #include <linux/hugetlb.h>
   5
   6 static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
   7                           struct mm_walk *walk)
   8 {
   9         pte_t *pte;
  10         int err = 0;
  11
  12         pte = pte_offset_map(pmd, addr);
  13         for (;;) {
  14                 err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
  15                 if (err)
  16                        break;
  17                 addr += PAGE_SIZE;
  18                 if (addr == end)
  19                         break;
  20                 pte++;
  21         }
  22
  23         pte_unmap(pte);
  24         return err;
  25 }
  26
  27 static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
  28                           struct mm_walk *walk)
  29 {
  30         pmd_t *pmd;
  31         unsigned long next;
  32         int err = 0;
  33
  34         pmd = pmd_offset(pud, addr);
  35         do {
  36                 next = pmd_addr_end(addr, end);
  37                 split_huge_page_pmd(walk->mm, pmd);
  38                 if (pmd_none_or_clear_bad(pmd)) {
  39                         if (walk->pte_hole)
  40                                 err = walk->pte_hole(addr, next, walk);
  41                         if (err)
  42                                 break;
  43                         continue;
  44                 }
  45                 if (walk->pmd_entry)
  46                         err = walk->pmd_entry(pmd, addr, next, walk);
  47                 if (!err && walk->pte_entry)
  48                         err = walk_pte_range(pmd, addr, next, walk);
  49                 if (err)
  50                         break;
  51         } while (pmd++, addr = next, addr != end);
  52
  53         return err;
  54 }
  55
  56 static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
  57                           struct mm_walk *walk)
  58 {
  59         pud_t *pud;
  60         unsigned long next;
  61         int err = 0;
  62
  63         pud = pud_offset(pgd, addr);
  64         do {
  65                 next = pud_addr_end(addr, end);
  66                 if (pud_none_or_clear_bad(pud)) {
  67                         if (walk->pte_hole)
  68                                 err = walk->pte_hole(addr, next, walk);
  69                         if (err)
  70                                 break;
  71                         continue;
  72                 }
  73                 if (walk->pud_entry)
  74                         err = walk->pud_entry(pud, addr, next, walk);
  75                 if (!err && (walk->pmd_entry || walk->pte_entry))
  76                         err = walk_pmd_range(pud, addr, next, walk);
  77                 if (err)
  78                         break;
  79         } while (pud++, addr = next, addr != end);
  80
  81         return err;
  82 }
  83
  84 #ifdef CONFIG_HUGETLB_PAGE
  85 static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
  86                                        unsigned long end)
  87 {
  88         unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
  89         return boundary < end ? boundary : end;
  90 }
  91
  92 static int walk_hugetlb_range(struct vm_area_struct *vma,
  93                               unsigned long addr, unsigned long end,
  94                               struct mm_walk *walk)
  95 {
  96         struct hstate *h = hstate_vma(vma);
  97         unsigned long next;
  98         unsigned long hmask = huge_page_mask(h);
  99         pte_t *pte;
 100         int err = 0;
 101
 102         do {
 103                 next = hugetlb_entry_end(h, addr, end);
 104                 pte = huge_pte_offset(walk->mm, addr & hmask);
 105                 if (pte && walk->hugetlb_entry)
 106                         err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
 107                 if (err)
 108                         return err;
 109         } while (addr = next, addr != end);
 110
 111         return 0;
 112 }
 113 #endif
 114
 115 /**
 116  * walk_page_range - walk a memory map's page tables with a callback
 117  * @mm: memory map to walk
 118  * @addr: starting address
 119  * @end: ending address
 120  * @walk: set of callbacks to invoke for each level of the tree
 121  *
 122  * Recursively walk the page table for the memory area in a VMA,
 123  * calling supplied callbacks. Callbacks are called in-order (first
 124  * PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
 125  * etc.). If lower-level callbacks are omitted, walking depth is reduced.
 126  *
 127  * Each callback receives an entry pointer and the start and end of the
 128  * associated range, and a copy of the original mm_walk for access to
 129  * the ->private or ->mm fields.
 130  *
 131  * No locks are taken, but the bottom level iterator will map PTE
 132  * directories from highmem if necessary.
 133  *
 134  * If any callback returns a non-zero value, the walk is aborted and
 135  * the return value is propagated back to the caller. Otherwise 0 is returned.
 136  */
 137 int walk_page_range(unsigned long addr, unsigned long end,
 138                     struct mm_walk *walk)
 139 {
 140         pgd_t *pgd;
 141         unsigned long next;
 142         int err = 0;
 143
 144         if (addr >= end)
 145                 return err;
 146
 147         if (!walk->mm)
 148                 return -EINVAL;
 149
 150         pgd = pgd_offset(walk->mm, addr);
 151         do {
 152                 struct vm_area_struct *uninitialized_var(vma);
 153
 154                 next = pgd_addr_end(addr, end);
 155
 156 #ifdef CONFIG_HUGETLB_PAGE
 157                 /*
 158                  * handle hugetlb vma individually because pagetable walk for
 159                  * the hugetlb page is dependent on the architecture and
 160                  * we can't handled it in the same manner as non-huge pages.
 161                  */
 162                 vma = find_vma(walk->mm, addr);
 163                 if (vma && is_vm_hugetlb_page(vma)) {
 164                         if (vma->vm_end < next)
 165                                 next = vma->vm_end;
 166                         /*
 167                          * Hugepage is very tightly coupled with vma, so
 168                          * walk through hugetlb entries within a given vma.
 169                          */
 170                         err = walk_hugetlb_range(vma, addr, next, walk);
 171                         if (err)
 172                                 break;
 173                         pgd = pgd_offset(walk->mm, next);
 174                         continue;
 175                 }
 176 #endif
 177                 if (pgd_none_or_clear_bad(pgd)) {
 178                         if (walk->pte_hole)
 179                                 err = walk->pte_hole(addr, next, walk);
 180                         if (err)
 181                                 break;
 182                         pgd++;
 183                         continue;
 184                 }
 185                 if (walk->pgd_entry)
 186                         err = walk->pgd_entry(pgd, addr, next, walk);
 187                 if (!err &&
 188                     (walk->pud_entry || walk->pmd_entry || walk->pte_entry))
 189                         err = walk_pud_range(pgd, addr, next, walk);
 190                 if (err)
 191                         break;
 192                 pgd++;
 193         } while (addr = next, addr != end);
 194
 195         return err;
 196 }