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  * 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  * 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 */
109