| /* 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_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 *, struct vm_area_struct *, |
| unsigned long, bool); |
| 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 */ |