From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- include/linux/rmap.h | 287 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 287 insertions(+) create mode 100644 include/linux/rmap.h (limited to 'include/linux/rmap.h') diff --git a/include/linux/rmap.h b/include/linux/rmap.h new file mode 100644 index 000000000..c89c53a11 --- /dev/null +++ b/include/linux/rmap.h @@ -0,0 +1,287 @@ +#ifndef _LINUX_RMAP_H +#define _LINUX_RMAP_H +/* + * Declarations for Reverse Mapping functions in mm/rmap.c + */ + +#include +#include +#include +#include +#include + +/* + * 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). + */ + struct rb_root rb_root; /* Interval tree of private "related" vmas */ +}; + +/* + * 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_sem & 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_UNMAP = 1, /* unmap mode */ + TTU_MIGRATION = 2, /* migration mode */ + TTU_MUNLOCK = 4, /* munlock mode */ + + TTU_IGNORE_MLOCK = (1 << 8), /* ignore mlock */ + TTU_IGNORE_ACCESS = (1 << 9), /* don't age */ + TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */ +}; + +#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 vma_lock_anon_vma(struct vm_area_struct *vma) +{ + struct anon_vma *anon_vma = vma->anon_vma; + if (anon_vma) + down_write(&anon_vma->root->rwsem); +} + +static inline void vma_unlock_anon_vma(struct vm_area_struct *vma) +{ + struct anon_vma *anon_vma = vma->anon_vma; + if (anon_vma) + up_write(&anon_vma->root->rwsem); +} + +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 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); + +/* + * rmap interfaces called when adding or removing pte of page + */ +void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); +void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); +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); +void page_add_file_rmap(struct page *); +void page_remove_rmap(struct page *); + +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) +{ + atomic_inc(&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); + +#define TTU_ACTION(x) ((x) & TTU_ACTION_MASK) + +int try_to_unmap(struct page *, enum ttu_flags flags); + +/* + * Used by uprobes to replace a userspace page safely + */ +pte_t *__page_check_address(struct page *, struct mm_struct *, + unsigned long, spinlock_t **, int); + +static inline pte_t *page_check_address(struct page *page, struct mm_struct *mm, + unsigned long address, + spinlock_t **ptlp, int sync) +{ + pte_t *ptep; + + __cond_lock(*ptlp, ptep = __page_check_address(page, mm, address, + ptlp, sync)); + return ptep; +} + +/* + * 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. + */ +int try_to_munlock(struct page *); + +/* + * 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; + int (*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); +}; + +int rmap_walk(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) SWAP_FAIL + +static inline int page_mkclean(struct page *page) +{ + return 0; +} + + +#endif /* CONFIG_MMU */ + +/* + * Return values of try_to_unmap + */ +#define SWAP_SUCCESS 0 +#define SWAP_AGAIN 1 +#define SWAP_FAIL 2 +#define SWAP_MLOCK 3 + +#endif /* _LINUX_RMAP_H */ -- cgit v1.2.3-54-g00ecf