LXR linux/mm/pagewalk.c

   1#include <linux/mm.h>
   2#include <linux/highmem.h>
   3#include <linux/sched.h>
   4#include <linux/hugetlb.h>
   5
   6static 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
  27static 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
  56static 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
  85static 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
  92static 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 */
 137int 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}
 197