1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef _LINUX_PAGEWALK_H
  3#define _LINUX_PAGEWALK_H
  4
  5#include <linux/mm.h>
  6
  7struct 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 */
 37struct 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 */
 64enum 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 */
 85struct 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
 95int walk_page_range(struct mm_struct *mm, unsigned long start,
 96		unsigned long end, const struct mm_walk_ops *ops,
 97		void *private);
 98int 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);
102int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
103		void *private);
104int 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 */