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 /**
  84  * walk_page_range - walk a memory map's page tables with a callback
  85  * @mm: memory map to walk
  86  * @addr: starting address
  87  * @end: ending address
  88  * @walk: set of callbacks to invoke for each level of the tree
  89  *
  90  * Recursively walk the page table for the memory area in a VMA,
  91  * calling supplied callbacks. Callbacks are called in-order (first
  92  * PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
  93  * etc.). If lower-level callbacks are omitted, walking depth is reduced.
  94  *
  95  * Each callback receives an entry pointer and the start and end of the
  96  * associated range, and a copy of the original mm_walk for access to
  97  * the ->private or ->mm fields.
  98  *
  99  * No locks are taken, but the bottom level iterator will map PTE
 100  * directories from highmem if necessary.
 101  *
 102  * If any callback returns a non-zero value, the walk is aborted and
 103  * the return value is propagated back to the caller. Otherwise 0 is returned.
 104  */
 105 int walk_page_range(unsigned long addr, unsigned long end,
 106                     struct mm_walk *walk)
 107 {
 108         pgd_t *pgd;
 109         unsigned long next;
 110         int err = 0;
 111         struct vm_area_struct *vma;
 112
 113         if (addr >= end)
 114                 return err;
 115
 116         if (!walk->mm)
 117                 return -EINVAL;
 118
 119         pgd = pgd_offset(walk->mm, addr);
 120         do {
 121                 next = pgd_addr_end(addr, end);
 122
 123                 /* skip hugetlb vma to avoid hugepage PMD being cleared
 124                  * in pmd_none_or_clear_bad(). */
 125                 vma = find_vma(walk->mm, addr);
 126                 if (vma && is_vm_hugetlb_page(vma)) {
 127                         if (vma->vm_end < next)
 128                                 next = vma->vm_end;
 129                         continue;
 130                 }
 131
 132                 if (pgd_none_or_clear_bad(pgd)) {
 133                         if (walk->pte_hole)
 134                                 err = walk->pte_hole(addr, next, walk);
 135                         if (err)
 136                                 break;
 137                         pgd++;
 138                         continue;
 139                 }
 140                 if (walk->pgd_entry)
 141                         err = walk->pgd_entry(pgd, addr, next, walk);
 142                 if (!err &&
 143                     (walk->pud_entry || walk->pmd_entry || walk->pte_entry))
 144                         err = walk_pud_range(pgd, addr, next, walk);
 145                 if (err)
 146                         break;
 147                 pgd++;
 148         } while (addr = next, addr != end);
 149
 150         return err;
 151 }