/* SPDX-License-Identifier: GPL-2.0 */

  #ifndef _LINUX_SWAPOPS_H
  #define _LINUX_SWAPOPS_H
  
  #include <linux/radix-tree.h>

  #include <linux/bug.h>

  #include <linux/mm_types.h>

  #ifdef CONFIG_MMU

  /*
   * swapcache pages are stored in the swapper_space radix tree.  We want to
   * get good packing density in that tree, so the index should be dense in
   * the low-order bits.
   *

   * We arrange the `type' and `offset' fields so that `type' is at the seven

   * high-order bits of the swp_entry_t and `offset' is right-aligned in the

   * remaining bits.  Although `type' itself needs only five bits, we allow for
   * shmem/tmpfs to shift it all up a further two bits: see swp_to_radix_entry().

   *
   * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
   */

  #define SWP_TYPE_SHIFT	(BITS_PER_XA_VALUE - MAX_SWAPFILES_SHIFT)
  #define SWP_OFFSET_MASK	((1UL << SWP_TYPE_SHIFT) - 1)

  
  /*
   * Store a type+offset into a swp_entry_t in an arch-independent format
   */
  static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
  {
  	swp_entry_t ret;

  	ret.val = (type << SWP_TYPE_SHIFT) | (offset & SWP_OFFSET_MASK);

  	return ret;
  }
  
  /*
   * Extract the `type' field from a swp_entry_t.  The swp_entry_t is in
   * arch-independent format
   */
  static inline unsigned swp_type(swp_entry_t entry)
  {

  	return (entry.val >> SWP_TYPE_SHIFT);

  }
  
  /*
   * Extract the `offset' field from a swp_entry_t.  The swp_entry_t is in
   * arch-independent format
   */
  static inline pgoff_t swp_offset(swp_entry_t entry)
  {

  	return entry.val & SWP_OFFSET_MASK;

  }

  /* check whether a pte points to a swap entry */
  static inline int is_swap_pte(pte_t pte)
  {

  	return !pte_none(pte) && !pte_present(pte);

  }

  /*
   * Convert the arch-dependent pte representation of a swp_entry_t into an
   * arch-independent swp_entry_t.
   */
  static inline swp_entry_t pte_to_swp_entry(pte_t pte)
  {
  	swp_entry_t arch_entry;

  	if (pte_swp_soft_dirty(pte))
  		pte = pte_swp_clear_soft_dirty(pte);

  	if (pte_swp_uffd_wp(pte))
  		pte = pte_swp_clear_uffd_wp(pte);

  	arch_entry = __pte_to_swp_entry(pte);
  	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
  }
  
  /*
   * Convert the arch-independent representation of a swp_entry_t into the
   * arch-dependent pte representation.
   */
  static inline pte_t swp_entry_to_pte(swp_entry_t entry)
  {
  	swp_entry_t arch_entry;
  
  	arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));

  	return __swp_entry_to_pte(arch_entry);
  }

  static inline swp_entry_t radix_to_swp_entry(void *arg)
  {
  	swp_entry_t entry;

  	entry.val = xa_to_value(arg);

  	return entry;
  }
  
  static inline void *swp_to_radix_entry(swp_entry_t entry)
  {

  	return xa_mk_value(entry.val);

  }

  #if IS_ENABLED(CONFIG_DEVICE_PRIVATE)
  static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
  {
  	return swp_entry(write ? SWP_DEVICE_WRITE : SWP_DEVICE_READ,
  			 page_to_pfn(page));
  }
  
  static inline bool is_device_private_entry(swp_entry_t entry)
  {
  	int type = swp_type(entry);
  	return type == SWP_DEVICE_READ || type == SWP_DEVICE_WRITE;
  }
  
  static inline void make_device_private_entry_read(swp_entry_t *entry)
  {
  	*entry = swp_entry(SWP_DEVICE_READ, swp_offset(*entry));
  }
  
  static inline bool is_write_device_private_entry(swp_entry_t entry)
  {
  	return unlikely(swp_type(entry) == SWP_DEVICE_WRITE);
  }

  static inline unsigned long device_private_entry_to_pfn(swp_entry_t entry)
  {
  	return swp_offset(entry);
  }

  static inline struct page *device_private_entry_to_page(swp_entry_t entry)
  {
  	return pfn_to_page(swp_offset(entry));
  }

  #else /* CONFIG_DEVICE_PRIVATE */
  static inline swp_entry_t make_device_private_entry(struct page *page, bool write)
  {
  	return swp_entry(0, 0);
  }
  
  static inline void make_device_private_entry_read(swp_entry_t *entry)
  {
  }
  
  static inline bool is_device_private_entry(swp_entry_t entry)
  {
  	return false;
  }
  
  static inline bool is_write_device_private_entry(swp_entry_t entry)
  {
  	return false;
  }

  static inline unsigned long device_private_entry_to_pfn(swp_entry_t entry)
  {
  	return 0;
  }

  static inline struct page *device_private_entry_to_page(swp_entry_t entry)
  {
  	return NULL;
  }

  #endif /* CONFIG_DEVICE_PRIVATE */

  #ifdef CONFIG_MIGRATION
  static inline swp_entry_t make_migration_entry(struct page *page, int write)
  {

  	BUG_ON(!PageLocked(compound_head(page)));

  	return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
  			page_to_pfn(page));
  }
  
  static inline int is_migration_entry(swp_entry_t entry)
  {
  	return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
  			swp_type(entry) == SWP_MIGRATION_WRITE);
  }
  
  static inline int is_write_migration_entry(swp_entry_t entry)
  {
  	return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
  }

  static inline unsigned long migration_entry_to_pfn(swp_entry_t entry)
  {
  	return swp_offset(entry);
  }

  static inline struct page *migration_entry_to_page(swp_entry_t entry)
  {
  	struct page *p = pfn_to_page(swp_offset(entry));
  	/*
  	 * Any use of migration entries may only occur while the
  	 * corresponding page is locked
  	 */

  	BUG_ON(!PageLocked(compound_head(p)));

  	return p;
  }
  
  static inline void make_migration_entry_read(swp_entry_t *entry)
  {
  	*entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
  }

  extern void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
  					spinlock_t *ptl);

  extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
  					unsigned long address);

  extern void migration_entry_wait_huge(struct vm_area_struct *vma,
  		struct mm_struct *mm, pte_t *pte);

  #else
  
  #define make_migration_entry(page, write) swp_entry(0, 0)

  static inline int is_migration_entry(swp_entry_t swp)
  {
  	return 0;
  }

  
  static inline unsigned long migration_entry_to_pfn(swp_entry_t entry)
  {
  	return 0;
  }

  static inline struct page *migration_entry_to_page(swp_entry_t entry)
  {
  	return NULL;
  }

  static inline void make_migration_entry_read(swp_entry_t *entryp) { }

  static inline void __migration_entry_wait(struct mm_struct *mm, pte_t *ptep,
  					spinlock_t *ptl) { }

  static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
  					 unsigned long address) { }

  static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
  		struct mm_struct *mm, pte_t *pte) { }

  static inline int is_write_migration_entry(swp_entry_t entry)
  {
  	return 0;
  }
  
  #endif

  struct page_vma_mapped_walk;
  
  #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
  extern void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
  		struct page *page);
  
  extern void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
  		struct page *new);
  
  extern void pmd_migration_entry_wait(struct mm_struct *mm, pmd_t *pmd);
  
  static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
  {
  	swp_entry_t arch_entry;

  	if (pmd_swp_soft_dirty(pmd))
  		pmd = pmd_swp_clear_soft_dirty(pmd);

  	arch_entry = __pmd_to_swp_entry(pmd);
  	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
  }
  
  static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
  {
  	swp_entry_t arch_entry;
  
  	arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
  	return __swp_entry_to_pmd(arch_entry);
  }
  
  static inline int is_pmd_migration_entry(pmd_t pmd)
  {
  	return !pmd_present(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
  }
  #else
  static inline void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
  		struct page *page)
  {
  	BUILD_BUG();
  }
  
  static inline void remove_migration_pmd(struct page_vma_mapped_walk *pvmw,
  		struct page *new)
  {
  	BUILD_BUG();
  }
  
  static inline void pmd_migration_entry_wait(struct mm_struct *m, pmd_t *p) { }
  
  static inline swp_entry_t pmd_to_swp_entry(pmd_t pmd)
  {
  	return swp_entry(0, 0);
  }
  
  static inline pmd_t swp_entry_to_pmd(swp_entry_t entry)
  {
  	return __pmd(0);
  }
  
  static inline int is_pmd_migration_entry(pmd_t pmd)
  {
  	return 0;
  }
  #endif

  #ifdef CONFIG_MEMORY_FAILURE

  
  extern atomic_long_t num_poisoned_pages __read_mostly;

  /*
   * Support for hardware poisoned pages
   */
  static inline swp_entry_t make_hwpoison_entry(struct page *page)
  {
  	BUG_ON(!PageLocked(page));
  	return swp_entry(SWP_HWPOISON, page_to_pfn(page));
  }
  
  static inline int is_hwpoison_entry(swp_entry_t entry)
  {
  	return swp_type(entry) == SWP_HWPOISON;
  }

  
  static inline void num_poisoned_pages_inc(void)
  {
  	atomic_long_inc(&num_poisoned_pages);
  }
  
  static inline void num_poisoned_pages_dec(void)
  {
  	atomic_long_dec(&num_poisoned_pages);
  }

  #else
  
  static inline swp_entry_t make_hwpoison_entry(struct page *page)
  {
  	return swp_entry(0, 0);
  }
  
  static inline int is_hwpoison_entry(swp_entry_t swp)
  {
  	return 0;
  }

  static inline void num_poisoned_pages_inc(void)
  {
  }

  #endif

  #if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION) || \
      defined(CONFIG_DEVICE_PRIVATE)

  static inline int non_swap_entry(swp_entry_t entry)
  {
  	return swp_type(entry) >= MAX_SWAPFILES;
  }
  #else
  static inline int non_swap_entry(swp_entry_t entry)
  {
  	return 0;
  }
  #endif

  #endif /* CONFIG_MMU */

  #endif /* _LINUX_SWAPOPS_H */