1 files changed, 306 insertions, 0 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
new file mode 100644
index 000000000..297744ea4
--- /dev/null
+++ b/include/linux/rmap.h
@@ -0,0 +1,306 @@
+/* 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. Equals to the count of all anon_vmas that
+	 * have ->parent pointing to this one, including itself.
+	 *
+	 * This counter is used for making decision about reusing anon_vma
+	 * instead of forking new one. See comments in function anon_vma_clone.
+	 */
+	unsigned long num_children;
+	/* Count of VMAs whose ->anon_vma pointer points to this object. */
+	unsigned long num_active_vmas;
+
+	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 *, 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 */