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 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) 23 * are skipped. 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 33 * accessing them. 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. 44 * 45 * p?d_entry callbacks are called even if those levels are folded on a 46 * particular architecture/configuration. 47 */ 48 struct mm_walk_ops { 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); 69 }; 70 71 /* 72 * Action for pud_entry / pmd_entry callbacks. 73 * ACTION_SUBTREE is the default 74 */ 75 enum page_walk_action { 76 /* Descend to next level, splitting huge pages if needed and possible */ 77 ACTION_SUBTREE = 0, 78 /* Continue to next entry at this level (ignoring any subtree) */ 79 ACTION_CONTINUE = 1, 80 /* Call again for this entry */ 81 ACTION_AGAIN = 2 82 }; 83 84 /** 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 93 * 94 * (see the comment on walk_page_range() for more details) 95 */ 96 struct mm_walk { 97 const struct mm_walk_ops *ops; 98 struct mm_struct *mm; 99 pgd_t *pgd; 100 struct vm_area_struct *vma; 101 enum page_walk_action action; 102 bool no_vma; 103 void *private; 104 }; 105 106 int walk_page_range(struct mm_struct *mm, unsigned long start, 107 unsigned long end, const struct mm_walk_ops *ops, 108 void *private); 109 int walk_page_range_novma(struct mm_struct *mm, unsigned long start, 110 unsigned long end, const struct mm_walk_ops *ops, 111 pgd_t *pgd, 112 void *private); 113 int walk_page_range_vma(struct vm_area_struct *vma, unsigned long start, 114 unsigned long end, const struct mm_walk_ops *ops, 115 void *private); 116 int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops, 117 void *private); 118 int walk_page_mapping(struct address_space *mapping, pgoff_t first_index, 119 pgoff_t nr, const struct mm_walk_ops *ops, 120 void *private); 121 122 #endif /* _LINUX_PAGEWALK_H */ 123