1 files changed, 384 insertions, 0 deletions
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
new file mode 100644
index 000000000..28d572b7e
--- /dev/null
+++ b/include/linux/swapops.h
@@ -0,0 +1,384 @@
+/* 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>
+
+/*
+ * 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(e)	((sizeof(e.val) * 8) - \
+			(MAX_SWAPFILES_SHIFT + RADIX_TREE_EXCEPTIONAL_SHIFT))
+#define SWP_OFFSET_MASK(e)	((1UL << SWP_TYPE_SHIFT(e)) - 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(ret)) |
+			(offset & SWP_OFFSET_MASK(ret));
+	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(entry));
+}
+
+/*
+ * 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(entry);
+}
+
+#ifdef CONFIG_MMU
+/* 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);
+}
+#endif
+
+/*
+ * 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);
+	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 = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
+	return entry;
+}
+
+static inline void *swp_to_radix_entry(swp_entry_t entry)
+{
+	unsigned long value;
+
+	value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT;
+	return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY);
+}
+
+#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));
+}
+
+vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
+		       unsigned long addr,
+		       swp_entry_t entry,
+		       unsigned int flags,
+		       pmd_t *pmdp);
+#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;
+}
+
+static inline vm_fault_t device_private_entry_fault(struct vm_area_struct *vma,
+				     unsigned long addr,
+				     swp_entry_t entry,
+				     unsigned int flags,
+				     pmd_t *pmdp)
+{
+	return VM_FAULT_SIGBUS;
+}
+#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 /* _LINUX_SWAPOPS_H */