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