mm/pagewalk.c

   1 #include <linux/mm.h>
   2 #include <linux/highmem.h>
   3 #include <linux/sched.h>
   4
   5 static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
   6                           struct mm_walk *walk)
   7 {
   8         pte_t *pte;
   9         int err = 0;
  10
  11         pte = pte_offset_map(pmd, addr);
  12         for (;;) {
  13                 err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
  14                 if (err)
  15                        break;
  16                 addr += PAGE_SIZE;
  17                 if (addr == end)
  18                         break;
  19                 pte++;
  20         }
  21
  22         pte_unmap(pte);
  23         return err;
  24 }
  25
  26 static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
  27                           struct mm_walk *walk)
  28 {
  29         pmd_t *pmd;
  30         unsigned long next;
  31         int err = 0;
  32
  33         pmd = pmd_offset(pud, addr);
  34         do {
  35                 next = pmd_addr_end(addr, end);
  36                 if (pmd_none_or_clear_bad(pmd)) {
  37                         if (walk->pte_hole)
  38                                 err = walk->pte_hole(addr, next, walk);
  39                         if (err)
  40                                 break;
  41                         continue;
  42                 }
  43                 if (walk->pmd_entry)
  44                         err = walk->pmd_entry(pmd, addr, next, walk);
  45                 if (!err && walk->pte_entry)
  46                         err = walk_pte_range(pmd, addr, next, walk);
  47                 if (err)
  48                         break;
  49         } while (pmd++, addr = next, addr != end);
  50
  51         return err;
  52 }
  53
  54 static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
  55                           struct mm_walk *walk)
  56 {
  57         pud_t *pud;
  58         unsigned long next;
  59         int err = 0;
  60
  61         pud = pud_offset(pgd, addr);
  62         do {
  63                 next = pud_addr_end(addr, end);
  64                 if (pud_none_or_clear_bad(pud)) {
  65                         if (walk->pte_hole)
  66                                 err = walk->pte_hole(addr, next, walk);
  67                         if (err)
  68                                 break;
  69                         continue;
  70                 }
  71                 if (walk->pud_entry)
  72                         err = walk->pud_entry(pud, addr, next, walk);
  73                 if (!err && (walk->pmd_entry || walk->pte_entry))
  74                         err = walk_pmd_range(pud, addr, next, walk);
  75                 if (err)
  76                         break;
  77         } while (pud++, addr = next, addr != end);
  78
  79         return err;
  80 }
  81
  82 /**
  83  * walk_page_range - walk a memory map's page tables with a callback
  84  * @mm: memory map to walk
  85  * @addr: starting address
  86  * @end: ending address
  87  * @walk: set of callbacks to invoke for each level of the tree
  88  *
  89  * Recursively walk the page table for the memory area in a VMA,
  90  * calling supplied callbacks. Callbacks are called in-order (first
  91  * PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
  92  * etc.). If lower-level callbacks are omitted, walking depth is reduced.
  93  *
  94  * Each callback receives an entry pointer and the start and end of the
  95  * associated range, and a copy of the original mm_walk for access to
  96  * the ->private or ->mm fields.
  97  *
  98  * No locks are taken, but the bottom level iterator will map PTE
  99  * directories from highmem if necessary.
 100  *
 101  * If any callback returns a non-zero value, the walk is aborted and
 102  * the return value is propagated back to the caller. Otherwise 0 is returned.
 103  */
 104 int walk_page_range(unsigned long addr, unsigned long end,
 105                     struct mm_walk *walk)
 106 {
 107         pgd_t *pgd;
 108         unsigned long next;
 109         int err = 0;
 110
 111         if (addr >= end)
 112                 return err;
 113
 114         if (!walk->mm)
 115                 return -EINVAL;
 116
 117         pgd = pgd_offset(walk->mm, addr);
 118         do {
 119                 next = pgd_addr_end(addr, end);
 120                 if (pgd_none_or_clear_bad(pgd)) {
 121                         if (walk->pte_hole)
 122                                 err = walk->pte_hole(addr, next, walk);
 123                         if (err)
 124                                 break;
 125                         continue;
 126                 }
 127                 if (walk->pgd_entry)
 128                         err = walk->pgd_entry(pgd, addr, next, walk);
 129                 if (!err &&
 130                     (walk->pud_entry || walk->pmd_entry || walk->pte_entry))
 131                         err = walk_pud_range(pgd, addr, next, walk);
 132                 if (err)
 133                         break;
 134         } while (pgd++, addr = next, addr != end);
 135
 136         return err;
 137 }