include/linux/pagewalk.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_PAGEWALK_H
   3 #define _LINUX_PAGEWALK_H
   4
   5 #include <linux/mm.h>
   6
   7 struct mm_walk;
   8
   9 /**
  10  * struct mm_walk_ops - callbacks for walk_page_range
  11  * @pgd_entry:          if set, called for each non-empty PGD (top-level) entry
  12  * @p4d_entry:          if set, called for each non-empty P4D entry
  13  * @pud_entry:          if set, called for each non-empty PUD entry
  14  * @pmd_entry:          if set, called for each non-empty PMD entry
  15  *                      this handler is required to be able to handle
  16  *                      pmd_trans_huge() pmds.  They may simply choose to
  17  *                      split_huge_page() instead of handling it explicitly.
  18  * @pte_entry:          if set, called for each non-empty PTE (lowest-level)
  19  *                      entry
  20  * @pte_hole:           if set, called for each hole at all levels,
  21  *                      depth is -1 if not known, 0:PGD, 1:P4D, 2:PUD, 3:PMD
  22  *                      4:PTE. Any folded depths (where PTRS_PER_P?D is equal
  23  *                      to 1) are skipped.
  24  * @hugetlb_entry:      if set, called for each hugetlb entry
  25  * @test_walk:          caller specific callback function to determine whether
  26  *                      we walk over the current vma or not. Returning 0 means
  27  *                      "do page table walk over the current vma", returning
  28  *                      a negative value means "abort current page table walk
  29  *                      right now" and returning 1 means "skip the current vma"
  30  * @pre_vma:            if set, called before starting walk on a non-null vma.
  31  * @post_vma:           if set, called after a walk on a non-null vma, provided
  32  *                      that @pre_vma and the vma walk succeeded.
  33  *
  34  * p?d_entry callbacks are called even if those levels are folded on a
  35  * particular architecture/configuration.
  36  */
  37 struct mm_walk_ops {
  38         int (*pgd_entry)(pgd_t *pgd, unsigned long addr,
  39                          unsigned long next, struct mm_walk *walk);
  40         int (*p4d_entry)(p4d_t *p4d, unsigned long addr,
  41                          unsigned long next, struct mm_walk *walk);
  42         int (*pud_entry)(pud_t *pud, unsigned long addr,
  43                          unsigned long next, struct mm_walk *walk);
  44         int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
  45                          unsigned long next, struct mm_walk *walk);
  46         int (*pte_entry)(pte_t *pte, unsigned long addr,
  47                          unsigned long next, struct mm_walk *walk);
  48         int (*pte_hole)(unsigned long addr, unsigned long next,
  49                         int depth, struct mm_walk *walk);
  50         int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
  51                              unsigned long addr, unsigned long next,
  52                              struct mm_walk *walk);
  53         int (*test_walk)(unsigned long addr, unsigned long next,
  54                         struct mm_walk *walk);
  55         int (*pre_vma)(unsigned long start, unsigned long end,
  56                        struct mm_walk *walk);
  57         void (*post_vma)(struct mm_walk *walk);
  58 };
  59
  60 /*
  61  * Action for pud_entry / pmd_entry callbacks.
  62  * ACTION_SUBTREE is the default
  63  */
  64 enum page_walk_action {
  65         /* Descend to next level, splitting huge pages if needed and possible */
  66         ACTION_SUBTREE = 0,
  67         /* Continue to next entry at this level (ignoring any subtree) */
  68         ACTION_CONTINUE = 1,
  69         /* Call again for this entry */
  70         ACTION_AGAIN = 2
  71 };
  72
  73 /**
  74  * struct mm_walk - walk_page_range data
  75  * @ops:        operation to call during the walk
  76  * @mm:         mm_struct representing the target process of page table walk
  77  * @pgd:        pointer to PGD; only valid with no_vma (otherwise set to NULL)
  78  * @vma:        vma currently walked (NULL if walking outside vmas)
  79  * @action:     next action to perform (see enum page_walk_action)
  80  * @no_vma:     walk ignoring vmas (vma will always be NULL)
  81  * @private:    private data for callbacks' usage
  82  *
  83  * (see the comment on walk_page_range() for more details)
  84  */
  85 struct mm_walk {
  86         const struct mm_walk_ops *ops;
  87         struct mm_struct *mm;
  88         pgd_t *pgd;
  89         struct vm_area_struct *vma;
  90         enum page_walk_action action;
  91         bool no_vma;
  92         void *private;
  93 };
  94
  95 int walk_page_range(struct mm_struct *mm, unsigned long start,
  96                 unsigned long end, const struct mm_walk_ops *ops,
  97                 void *private);
  98 int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
  99                           unsigned long end, const struct mm_walk_ops *ops,
 100                           pgd_t *pgd,
 101                           void *private);
 102 int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
 103                 void *private);
 104 int walk_page_mapping(struct address_space *mapping, pgoff_t first_index,
 105                       pgoff_t nr, const struct mm_walk_ops *ops,
 106                       void *private);
 107
 108 #endif /* _LINUX_PAGEWALK_H */