1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_PAGEWALK_H
3 #define _LINUX_PAGEWALK_H
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 PTE (lowest-level) entry,
19 * including empty ones
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 * Any folded depths (where PTRS_PER_P?D is equal to 1)
24 * @hugetlb_entry: if set, called for each hugetlb entry. This hook
25 * function is called with the vma lock held, in order to
26 * protect against a concurrent freeing of the pte_t* or
27 * the ptl. In some cases, the hook function needs to drop
28 * and retake the vma lock in order to avoid deadlocks
29 * while calling other functions. In such cases the hook
30 * function must either refrain from accessing the pte or
31 * ptl after dropping the vma lock, or else revalidate
32 * those items after re-acquiring the vma lock and before
34 * @test_walk: caller specific callback function to determine whether
35 * we walk over the current vma or not. Returning 0 means
36 * "do page table walk over the current vma", returning
37 * a negative value means "abort current page table walk
38 * right now" and returning 1 means "skip the current vma"
39 * Note that this callback is not called when the caller
40 * passes in a single VMA as for walk_page_vma().
41 * @pre_vma: if set, called before starting walk on a non-null vma.
42 * @post_vma: if set, called after a walk on a non-null vma, provided
43 * that @pre_vma and the vma walk succeeded.
45 * p?d_entry callbacks are called even if those levels are folded on a
46 * particular architecture/configuration.
49 int (*pgd_entry)(pgd_t *pgd, unsigned long addr,
50 unsigned long next, struct mm_walk *walk);
51 int (*p4d_entry)(p4d_t *p4d, unsigned long addr,
52 unsigned long next, struct mm_walk *walk);
53 int (*pud_entry)(pud_t *pud, unsigned long addr,
54 unsigned long next, struct mm_walk *walk);
55 int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
56 unsigned long next, struct mm_walk *walk);
57 int (*pte_entry)(pte_t *pte, unsigned long addr,
58 unsigned long next, struct mm_walk *walk);
59 int (*pte_hole)(unsigned long addr, unsigned long next,
60 int depth, struct mm_walk *walk);
61 int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
62 unsigned long addr, unsigned long next,
63 struct mm_walk *walk);
64 int (*test_walk)(unsigned long addr, unsigned long next,
65 struct mm_walk *walk);
66 int (*pre_vma)(unsigned long start, unsigned long end,
67 struct mm_walk *walk);
68 void (*post_vma)(struct mm_walk *walk);
72 * Action for pud_entry / pmd_entry callbacks.
73 * ACTION_SUBTREE is the default
75 enum page_walk_action {
76 /* Descend to next level, splitting huge pages if needed and possible */
78 /* Continue to next entry at this level (ignoring any subtree) */
80 /* Call again for this entry */
85 * struct mm_walk - walk_page_range data
86 * @ops: operation to call during the walk
87 * @mm: mm_struct representing the target process of page table walk
88 * @pgd: pointer to PGD; only valid with no_vma (otherwise set to NULL)
89 * @vma: vma currently walked (NULL if walking outside vmas)
90 * @action: next action to perform (see enum page_walk_action)
91 * @no_vma: walk ignoring vmas (vma will always be NULL)
92 * @private: private data for callbacks' usage
94 * (see the comment on walk_page_range() for more details)
97 const struct mm_walk_ops *ops;
100 struct vm_area_struct *vma;
101 enum page_walk_action action;
106 int walk_page_range(struct mm_struct *mm, unsigned long start,
107 unsigned long end, const struct mm_walk_ops *ops,
109 int walk_page_range_novma(struct mm_struct *mm, unsigned long start,
110 unsigned long end, const struct mm_walk_ops *ops,
113 int walk_page_range_vma(struct vm_area_struct *vma, unsigned long start,
114 unsigned long end, const struct mm_walk_ops *ops,
116 int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
118 int walk_page_mapping(struct address_space *mapping, pgoff_t first_index,
119 pgoff_t nr, const struct mm_walk_ops *ops,
122 #endif /* _LINUX_PAGEWALK_H */