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- /* SPDX-License-Identifier: GPL-2.0 */
- #ifndef _LINUX_RMAP_H
- #define _LINUX_RMAP_H
- /*
- * Declarations for Reverse Mapping functions in mm/rmap.c
- */
- #include <linux/list.h>
- #include <linux/slab.h>
- #include <linux/mm.h>
- #include <linux/rwsem.h>
- #include <linux/memcontrol.h>
- #include <linux/highmem.h>
- /*
- * The anon_vma heads a list of private "related" vmas, to scan if
- * an anonymous page pointing to this anon_vma needs to be unmapped:
- * the vmas on the list will be related by forking, or by splitting.
- *
- * Since vmas come and go as they are split and merged (particularly
- * in mprotect), the mapping field of an anonymous page cannot point
- * directly to a vma: instead it points to an anon_vma, on whose list
- * the related vmas can be easily linked or unlinked.
- *
- * After unlinking the last vma on the list, we must garbage collect
- * the anon_vma object itself: we're guaranteed no page can be
- * pointing to this anon_vma once its vma list is empty.
- */
- struct anon_vma {
- struct anon_vma *root; /* Root of this anon_vma tree */
- struct rw_semaphore rwsem; /* W: modification, R: walking the list */
- /*
- * The refcount is taken on an anon_vma when there is no
- * guarantee that the vma of page tables will exist for
- * the duration of the operation. A caller that takes
- * the reference is responsible for clearing up the
- * anon_vma if they are the last user on release
- */
- atomic_t refcount;
- /*
- * Count of child anon_vmas and VMAs which points to this anon_vma.
- *
- * This counter is used for making decision about reusing anon_vma
- * instead of forking new one. See comments in function anon_vma_clone.
- */
- unsigned degree;
- struct anon_vma *parent; /* Parent of this anon_vma */
- /*
- * NOTE: the LSB of the rb_root.rb_node is set by
- * mm_take_all_locks() _after_ taking the above lock. So the
- * rb_root must only be read/written after taking the above lock
- * to be sure to see a valid next pointer. The LSB bit itself
- * is serialized by a system wide lock only visible to
- * mm_take_all_locks() (mm_all_locks_mutex).
- */
- /* Interval tree of private "related" vmas */
- struct rb_root_cached rb_root;
- };
- /*
- * The copy-on-write semantics of fork mean that an anon_vma
- * can become associated with multiple processes. Furthermore,
- * each child process will have its own anon_vma, where new
- * pages for that process are instantiated.
- *
- * This structure allows us to find the anon_vmas associated
- * with a VMA, or the VMAs associated with an anon_vma.
- * The "same_vma" list contains the anon_vma_chains linking
- * all the anon_vmas associated with this VMA.
- * The "rb" field indexes on an interval tree the anon_vma_chains
- * which link all the VMAs associated with this anon_vma.
- */
- struct anon_vma_chain {
- struct vm_area_struct *vma;
- struct anon_vma *anon_vma;
- struct list_head same_vma; /* locked by mmap_lock & page_table_lock */
- struct rb_node rb; /* locked by anon_vma->rwsem */
- unsigned long rb_subtree_last;
- #ifdef CONFIG_DEBUG_VM_RB
- unsigned long cached_vma_start, cached_vma_last;
- #endif
- };
- enum ttu_flags {
- TTU_MIGRATION = 0x1, /* migration mode */
- TTU_MUNLOCK = 0x2, /* munlock mode */
- TTU_SPLIT_HUGE_PMD = 0x4, /* split huge PMD if any */
- TTU_IGNORE_MLOCK = 0x8, /* ignore mlock */
- TTU_SYNC = 0x10, /* avoid racy checks with PVMW_SYNC */
- TTU_IGNORE_HWPOISON = 0x20, /* corrupted page is recoverable */
- TTU_BATCH_FLUSH = 0x40, /* Batch TLB flushes where possible
- * and caller guarantees they will
- * do a final flush if necessary */
- TTU_RMAP_LOCKED = 0x80, /* do not grab rmap lock:
- * caller holds it */
- TTU_SPLIT_FREEZE = 0x100, /* freeze pte under splitting thp */
- };
- #ifdef CONFIG_MMU
- static inline void get_anon_vma(struct anon_vma *anon_vma)
- {
- atomic_inc(&anon_vma->refcount);
- }
- void __put_anon_vma(struct anon_vma *anon_vma);
- static inline void put_anon_vma(struct anon_vma *anon_vma)
- {
- if (atomic_dec_and_test(&anon_vma->refcount))
- __put_anon_vma(anon_vma);
- }
- static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
- {
- down_write(&anon_vma->root->rwsem);
- }
- static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
- {
- up_write(&anon_vma->root->rwsem);
- }
- static inline void anon_vma_lock_read(struct anon_vma *anon_vma)
- {
- down_read(&anon_vma->root->rwsem);
- }
- static inline void anon_vma_unlock_read(struct anon_vma *anon_vma)
- {
- up_read(&anon_vma->root->rwsem);
- }
- /*
- * anon_vma helper functions.
- */
- void anon_vma_init(void); /* create anon_vma_cachep */
- int __anon_vma_prepare(struct vm_area_struct *);
- void unlink_anon_vmas(struct vm_area_struct *);
- int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
- int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
- static inline int anon_vma_prepare(struct vm_area_struct *vma)
- {
- if (likely(vma->anon_vma))
- return 0;
- return __anon_vma_prepare(vma);
- }
- static inline void anon_vma_merge(struct vm_area_struct *vma,
- struct vm_area_struct *next)
- {
- VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
- unlink_anon_vmas(next);
- }
- struct anon_vma *page_get_anon_vma(struct page *page);
- /* bitflags for do_page_add_anon_rmap() */
- #define RMAP_EXCLUSIVE 0x01
- #define RMAP_COMPOUND 0x02
- /*
- * rmap interfaces called when adding or removing pte of page
- */
- void page_move_anon_rmap(struct page *, struct vm_area_struct *);
- void page_add_anon_rmap(struct page *, struct vm_area_struct *,
- unsigned long, bool);
- void do_page_add_anon_rmap(struct page *, struct vm_area_struct *,
- unsigned long, int);
- void __page_add_new_anon_rmap(struct page *page, struct vm_area_struct *vma,
- unsigned long address, bool compound);
- static inline void page_add_new_anon_rmap(struct page *page,
- struct vm_area_struct *vma,
- unsigned long address, bool compound)
- {
- VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
- __page_add_new_anon_rmap(page, vma, address, compound);
- }
- void page_add_file_rmap(struct page *, bool);
- void page_remove_rmap(struct page *, bool);
- void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *,
- unsigned long);
- void hugepage_add_new_anon_rmap(struct page *, struct vm_area_struct *,
- unsigned long);
- static inline void page_dup_rmap(struct page *page, bool compound)
- {
- atomic_inc(compound ? compound_mapcount_ptr(page) : &page->_mapcount);
- }
- /*
- * Called from mm/vmscan.c to handle paging out
- */
- int page_referenced(struct page *, int is_locked,
- struct mem_cgroup *memcg, unsigned long *vm_flags);
- bool try_to_unmap(struct page *, enum ttu_flags flags);
- /* Avoid racy checks */
- #define PVMW_SYNC (1 << 0)
- /* Look for migarion entries rather than present PTEs */
- #define PVMW_MIGRATION (1 << 1)
- struct page_vma_mapped_walk {
- struct page *page;
- struct vm_area_struct *vma;
- unsigned long address;
- pmd_t *pmd;
- pte_t *pte;
- spinlock_t *ptl;
- unsigned int flags;
- };
- static inline void page_vma_mapped_walk_done(struct page_vma_mapped_walk *pvmw)
- {
- /* HugeTLB pte is set to the relevant page table entry without pte_mapped. */
- if (pvmw->pte && !PageHuge(pvmw->page))
- pte_unmap(pvmw->pte);
- if (pvmw->ptl)
- spin_unlock(pvmw->ptl);
- }
- bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw);
- /*
- * Used by swapoff to help locate where page is expected in vma.
- */
- unsigned long page_address_in_vma(struct page *, struct vm_area_struct *);
- /*
- * Cleans the PTEs of shared mappings.
- * (and since clean PTEs should also be readonly, write protects them too)
- *
- * returns the number of cleaned PTEs.
- */
- int page_mkclean(struct page *);
- /*
- * called in munlock()/munmap() path to check for other vmas holding
- * the page mlocked.
- */
- void try_to_munlock(struct page *);
- void remove_migration_ptes(struct page *old, struct page *new, bool locked);
- /*
- * Called by memory-failure.c to kill processes.
- */
- struct anon_vma *page_lock_anon_vma_read(struct page *page);
- void page_unlock_anon_vma_read(struct anon_vma *anon_vma);
- int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
- /*
- * rmap_walk_control: To control rmap traversing for specific needs
- *
- * arg: passed to rmap_one() and invalid_vma()
- * rmap_one: executed on each vma where page is mapped
- * done: for checking traversing termination condition
- * anon_lock: for getting anon_lock by optimized way rather than default
- * invalid_vma: for skipping uninterested vma
- */
- struct rmap_walk_control {
- void *arg;
- /*
- * Return false if page table scanning in rmap_walk should be stopped.
- * Otherwise, return true.
- */
- bool (*rmap_one)(struct page *page, struct vm_area_struct *vma,
- unsigned long addr, void *arg);
- int (*done)(struct page *page);
- struct anon_vma *(*anon_lock)(struct page *page);
- bool (*invalid_vma)(struct vm_area_struct *vma, void *arg);
- };
- void rmap_walk(struct page *page, struct rmap_walk_control *rwc);
- void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc);
- #else /* !CONFIG_MMU */
- #define anon_vma_init() do {} while (0)
- #define anon_vma_prepare(vma) (0)
- #define anon_vma_link(vma) do {} while (0)
- static inline int page_referenced(struct page *page, int is_locked,
- struct mem_cgroup *memcg,
- unsigned long *vm_flags)
- {
- *vm_flags = 0;
- return 0;
- }
- #define try_to_unmap(page, refs) false
- static inline int page_mkclean(struct page *page)
- {
- return 0;
- }
- #endif /* CONFIG_MMU */
- #endif /* _LINUX_RMAP_H */
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