/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_PAGEWALK_H
#define _LINUX_PAGEWALK_H

#include <linux/mm.h>

struct mm_walk;


enum page_walk_lock {
	
	PGWALK_RDLOCK = 0,
	
	PGWALK_WRLOCK = 1,
	
	PGWALK_WRLOCK_VERIFY = 2,
	
	PGWALK_VMA_RDLOCK_VERIFY = 3,
};


struct mm_walk_ops {
	int (*pgd_entry)(pgd_t *pgd, unsigned long addr,
			 unsigned long next, struct mm_walk *walk);
	int (*p4d_entry)(p4d_t *p4d, unsigned long addr,
			 unsigned long next, struct mm_walk *walk);
	int (*pud_entry)(pud_t *pud, unsigned long addr,
			 unsigned long next, struct mm_walk *walk);
	int (*pmd_entry)(pmd_t *pmd, unsigned long addr,
			 unsigned long next, struct mm_walk *walk);
	int (*pte_entry)(pte_t *pte, unsigned long addr,
			 unsigned long next, struct mm_walk *walk);
	int (*pte_hole)(unsigned long addr, unsigned long next,
			int depth, struct mm_walk *walk);
	int (*hugetlb_entry)(pte_t *pte, unsigned long hmask,
			     unsigned long addr, unsigned long next,
			     struct mm_walk *walk);
	int (*test_walk)(unsigned long addr, unsigned long next,
			struct mm_walk *walk);
	int (*pre_vma)(unsigned long start, unsigned long end,
		       struct mm_walk *walk);
	void (*post_vma)(struct mm_walk *walk);
	int (*install_pte)(unsigned long addr, unsigned long next,
			   pte_t *ptep, struct mm_walk *walk);
	enum page_walk_lock walk_lock;
};


enum page_walk_action {
	
	ACTION_SUBTREE = 0,
	
	ACTION_CONTINUE = 1,
	
	ACTION_AGAIN = 2
};


struct mm_walk {
	const struct mm_walk_ops *ops;
	struct mm_struct *mm;
	pgd_t *pgd;
	struct vm_area_struct *vma;
	enum page_walk_action action;
	bool no_vma;
	void *private;
};

int walk_page_range(struct mm_struct *mm, unsigned long start,
		unsigned long end, const struct mm_walk_ops *ops,
		void *private);
int walk_kernel_page_table_range(unsigned long start,
		unsigned long end, const struct mm_walk_ops *ops,
		pgd_t *pgd, void *private);
int walk_kernel_page_table_range_lockless(unsigned long start,
		unsigned long end, const struct mm_walk_ops *ops,
		pgd_t *pgd, void *private);
int walk_page_range_vma(struct vm_area_struct *vma, unsigned long start,
			unsigned long end, const struct mm_walk_ops *ops,
			void *private);
int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops,
		void *private);
int walk_page_mapping(struct address_space *mapping, pgoff_t first_index,
		      pgoff_t nr, const struct mm_walk_ops *ops,
		      void *private);

typedef int __bitwise folio_walk_flags_t;


#define FW_MIGRATION			((__force folio_walk_flags_t)BIT(0))


#define FW_ZEROPAGE			((__force folio_walk_flags_t)BIT(1))

enum folio_walk_level {
	FW_LEVEL_PTE,
	FW_LEVEL_PMD,
	FW_LEVEL_PUD,
};


struct folio_walk {
	
	struct page *page;
	enum folio_walk_level level;
	union {
		pte_t *ptep;
		pud_t *pudp;
		pmd_t *pmdp;
	};
	union {
		pte_t pte;
		pud_t pud;
		pmd_t pmd;
	};
	
	struct vm_area_struct *vma;
	spinlock_t *ptl;
};

struct folio *folio_walk_start(struct folio_walk *fw,
		struct vm_area_struct *vma, unsigned long addr,
		folio_walk_flags_t flags);

#define folio_walk_end(__fw, __vma) do { \
	spin_unlock((__fw)->ptl); \
	if (likely((__fw)->level == FW_LEVEL_PTE)) \
		pte_unmap((__fw)->ptep); \
	vma_pgtable_walk_end(__vma); \
} while (0)

#endif 
