1 files changed, 619 insertions, 0 deletions
diff --git a/include/linux/leafops.h b/include/linux/leafops.h
new file mode 100644
index 000000000000..cfafe7a5e7b1
--- /dev/null
+++ b/include/linux/leafops.h
@@ -0,0 +1,619 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Describes operations that can be performed on software-defined page table
+ * leaf entries. These are abstracted from the hardware page table entries
+ * themselves by the softleaf_t type, see mm_types.h.
+ */
+#ifndef _LINUX_LEAFOPS_H
+#define _LINUX_LEAFOPS_H
+
+#include <linux/mm_types.h>
+#include <linux/swapops.h>
+#include <linux/swap.h>
+
+#ifdef CONFIG_MMU
+
+/* Temporary until swp_entry_t eliminated. */
+#define LEAF_TYPE_SHIFT SWP_TYPE_SHIFT
+
+enum softleaf_type {
+	/* Fundamental types. */
+	SOFTLEAF_NONE,
+	SOFTLEAF_SWAP,
+	/* Migration types. */
+	SOFTLEAF_MIGRATION_READ,
+	SOFTLEAF_MIGRATION_READ_EXCLUSIVE,
+	SOFTLEAF_MIGRATION_WRITE,
+	/* Device types. */
+	SOFTLEAF_DEVICE_PRIVATE_READ,
+	SOFTLEAF_DEVICE_PRIVATE_WRITE,
+	SOFTLEAF_DEVICE_EXCLUSIVE,
+	/* H/W posion types. */
+	SOFTLEAF_HWPOISON,
+	/* Marker types. */
+	SOFTLEAF_MARKER,
+};
+
+/**
+ * softleaf_mk_none() - Create an empty ('none') leaf entry.
+ * Returns: empty leaf entry.
+ */
+static inline softleaf_t softleaf_mk_none(void)
+{
+	return ((softleaf_t) { 0 });
+}
+
+/**
+ * softleaf_from_pte() - Obtain a leaf entry from a PTE entry.
+ * @pte: PTE entry.
+ *
+ * If @pte is present (therefore not a leaf entry) the function returns an empty
+ * leaf entry. Otherwise, it returns a leaf entry.
+ *
+ * Returns: Leaf entry.
+ */
+static inline softleaf_t softleaf_from_pte(pte_t pte)
+{
+	softleaf_t arch_entry;
+
+	if (pte_present(pte) || pte_none(pte))
+		return softleaf_mk_none();
+
+	pte = pte_swp_clear_flags(pte);
+	arch_entry = __pte_to_swp_entry(pte);
+
+	/* Temporary until swp_entry_t eliminated. */
+	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
+}
+
+/**
+ * softleaf_to_pte() - Obtain a PTE entry from a leaf entry.
+ * @entry: Leaf entry.
+ *
+ * This generates an architecture-specific PTE entry that can be utilised to
+ * encode the metadata the leaf entry encodes.
+ *
+ * Returns: Architecture-specific PTE entry encoding leaf entry.
+ */
+static inline pte_t softleaf_to_pte(softleaf_t entry)
+{
+	/* Temporary until swp_entry_t eliminated. */
+	return swp_entry_to_pte(entry);
+}
+
+#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION
+/**
+ * softleaf_from_pmd() - Obtain a leaf entry from a PMD entry.
+ * @pmd: PMD entry.
+ *
+ * If @pmd is present (therefore not a leaf entry) the function returns an empty
+ * leaf entry. Otherwise, it returns a leaf entry.
+ *
+ * Returns: Leaf entry.
+ */
+static inline softleaf_t softleaf_from_pmd(pmd_t pmd)
+{
+	softleaf_t arch_entry;
+
+	if (pmd_present(pmd) || pmd_none(pmd))
+		return softleaf_mk_none();
+
+	if (pmd_swp_soft_dirty(pmd))
+		pmd = pmd_swp_clear_soft_dirty(pmd);
+	if (pmd_swp_uffd_wp(pmd))
+		pmd = pmd_swp_clear_uffd_wp(pmd);
+	arch_entry = __pmd_to_swp_entry(pmd);
+
+	/* Temporary until swp_entry_t eliminated. */
+	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
+}
+
+#else
+
+static inline softleaf_t softleaf_from_pmd(pmd_t pmd)
+{
+	return softleaf_mk_none();
+}
+
+#endif
+
+/**
+ * softleaf_is_none() - Is the leaf entry empty?
+ * @entry: Leaf entry.
+ *
+ * Empty entries are typically the result of a 'none' page table leaf entry
+ * being converted to a leaf entry.
+ *
+ * Returns: true if the entry is empty, false otherwise.
+ */
+static inline bool softleaf_is_none(softleaf_t entry)
+{
+	return entry.val == 0;
+}
+
+/**
+ * softleaf_type() - Identify the type of leaf entry.
+ * @enntry: Leaf entry.
+ *
+ * Returns: the leaf entry type associated with @entry.
+ */
+static inline enum softleaf_type softleaf_type(softleaf_t entry)
+{
+	unsigned int type_num;
+
+	if (softleaf_is_none(entry))
+		return SOFTLEAF_NONE;
+
+	type_num = entry.val >> LEAF_TYPE_SHIFT;
+
+	if (type_num < MAX_SWAPFILES)
+		return SOFTLEAF_SWAP;
+
+	switch (type_num) {
+#ifdef CONFIG_MIGRATION
+	case SWP_MIGRATION_READ:
+		return SOFTLEAF_MIGRATION_READ;
+	case SWP_MIGRATION_READ_EXCLUSIVE:
+		return SOFTLEAF_MIGRATION_READ_EXCLUSIVE;
+	case SWP_MIGRATION_WRITE:
+		return SOFTLEAF_MIGRATION_WRITE;
+#endif
+#ifdef CONFIG_DEVICE_PRIVATE
+	case SWP_DEVICE_WRITE:
+		return SOFTLEAF_DEVICE_PRIVATE_WRITE;
+	case SWP_DEVICE_READ:
+		return SOFTLEAF_DEVICE_PRIVATE_READ;
+	case SWP_DEVICE_EXCLUSIVE:
+		return SOFTLEAF_DEVICE_EXCLUSIVE;
+#endif
+#ifdef CONFIG_MEMORY_FAILURE
+	case SWP_HWPOISON:
+		return SOFTLEAF_HWPOISON;
+#endif
+	case SWP_PTE_MARKER:
+		return SOFTLEAF_MARKER;
+	}
+
+	/* Unknown entry type. */
+	VM_WARN_ON_ONCE(1);
+	return SOFTLEAF_NONE;
+}
+
+/**
+ * softleaf_is_swap() - Is this leaf entry a swap entry?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is a swap entry, otherwise false.
+ */
+static inline bool softleaf_is_swap(softleaf_t entry)
+{
+	return softleaf_type(entry) == SOFTLEAF_SWAP;
+}
+
+/**
+ * softleaf_is_migration_write() - Is this leaf entry a writable migration entry?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is a writable migration entry, otherwise
+ * false.
+ */
+static inline bool softleaf_is_migration_write(softleaf_t entry)
+{
+	return softleaf_type(entry) == SOFTLEAF_MIGRATION_WRITE;
+}
+
+/**
+ * softleaf_is_migration_read() - Is this leaf entry a readable migration entry?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is a readable migration entry, otherwise
+ * false.
+ */
+static inline bool softleaf_is_migration_read(softleaf_t entry)
+{
+	return softleaf_type(entry) == SOFTLEAF_MIGRATION_READ;
+}
+
+/**
+ * softleaf_is_migration_read_exclusive() - Is this leaf entry an exclusive
+ * readable migration entry?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is an exclusive readable migration entry,
+ * otherwise false.
+ */
+static inline bool softleaf_is_migration_read_exclusive(softleaf_t entry)
+{
+	return softleaf_type(entry) == SOFTLEAF_MIGRATION_READ_EXCLUSIVE;
+}
+
+/**
+ * softleaf_is_migration() - Is this leaf entry a migration entry?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is a migration entry, otherwise false.
+ */
+static inline bool softleaf_is_migration(softleaf_t entry)
+{
+	switch (softleaf_type(entry)) {
+	case SOFTLEAF_MIGRATION_READ:
+	case SOFTLEAF_MIGRATION_READ_EXCLUSIVE:
+	case SOFTLEAF_MIGRATION_WRITE:
+		return true;
+	default:
+		return false;
+	}
+}
+
+/**
+ * softleaf_is_device_private_write() - Is this leaf entry a device private
+ * writable entry?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is a device private writable entry, otherwise
+ * false.
+ */
+static inline bool softleaf_is_device_private_write(softleaf_t entry)
+{
+	return softleaf_type(entry) == SOFTLEAF_DEVICE_PRIVATE_WRITE;
+}
+
+/**
+ * softleaf_is_device_private() - Is this leaf entry a device private entry?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is a device private entry, otherwise false.
+ */
+static inline bool softleaf_is_device_private(softleaf_t entry)
+{
+	switch (softleaf_type(entry)) {
+	case SOFTLEAF_DEVICE_PRIVATE_WRITE:
+	case SOFTLEAF_DEVICE_PRIVATE_READ:
+		return true;
+	default:
+		return false;
+	}
+}
+
+/**
+ * softleaf_is_device_exclusive() - Is this leaf entry a device-exclusive entry?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is a device-exclusive entry, otherwise false.
+ */
+static inline bool softleaf_is_device_exclusive(softleaf_t entry)
+{
+	return softleaf_type(entry) == SOFTLEAF_DEVICE_EXCLUSIVE;
+}
+
+/**
+ * softleaf_is_hwpoison() - Is this leaf entry a hardware poison entry?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is a hardware poison entry, otherwise false.
+ */
+static inline bool softleaf_is_hwpoison(softleaf_t entry)
+{
+	return softleaf_type(entry) == SOFTLEAF_HWPOISON;
+}
+
+/**
+ * softleaf_is_marker() - Is this leaf entry a marker?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is a marker entry, otherwise false.
+ */
+static inline bool softleaf_is_marker(softleaf_t entry)
+{
+	return softleaf_type(entry) == SOFTLEAF_MARKER;
+}
+
+/**
+ * softleaf_to_marker() - Obtain marker associated with leaf entry.
+ * @entry: Leaf entry, softleaf_is_marker(@entry) must return true.
+ *
+ * Returns: Marker associated with the leaf entry.
+ */
+static inline pte_marker softleaf_to_marker(softleaf_t entry)
+{
+	VM_WARN_ON_ONCE(!softleaf_is_marker(entry));
+
+	return swp_offset(entry) & PTE_MARKER_MASK;
+}
+
+/**
+ * softleaf_has_pfn() - Does this leaf entry encode a valid PFN number?
+ * @entry: Leaf entry.
+ *
+ * A pfn swap entry is a special type of swap entry that always has a pfn stored
+ * in the swap offset. They can either be used to represent unaddressable device
+ * memory, to restrict access to a page undergoing migration or to represent a
+ * pfn which has been hwpoisoned and unmapped.
+ *
+ * Returns: true if the leaf entry encodes a PFN, otherwise false.
+ */
+static inline bool softleaf_has_pfn(softleaf_t entry)
+{
+	/* Make sure the swp offset can always store the needed fields. */
+	BUILD_BUG_ON(SWP_TYPE_SHIFT < SWP_PFN_BITS);
+
+	if (softleaf_is_migration(entry))
+		return true;
+	if (softleaf_is_device_private(entry))
+		return true;
+	if (softleaf_is_device_exclusive(entry))
+		return true;
+	if (softleaf_is_hwpoison(entry))
+		return true;
+
+	return false;
+}
+
+/**
+ * softleaf_to_pfn() - Obtain PFN encoded within leaf entry.
+ * @entry: Leaf entry, softleaf_has_pfn(@entry) must return true.
+ *
+ * Returns: The PFN associated with the leaf entry.
+ */
+static inline unsigned long softleaf_to_pfn(softleaf_t entry)
+{
+	VM_WARN_ON_ONCE(!softleaf_has_pfn(entry));
+
+	/* Temporary until swp_entry_t eliminated. */
+	return swp_offset(entry) & SWP_PFN_MASK;
+}
+
+/**
+ * softleaf_to_page() - Obtains struct page for PFN encoded within leaf entry.
+ * @entry: Leaf entry, softleaf_has_pfn(@entry) must return true.
+ *
+ * Returns: Pointer to the struct page associated with the leaf entry's PFN.
+ */
+static inline struct page *softleaf_to_page(softleaf_t entry)
+{
+	struct page *page = pfn_to_page(softleaf_to_pfn(entry));
+
+	VM_WARN_ON_ONCE(!softleaf_has_pfn(entry));
+	/*
+	 * Any use of migration entries may only occur while the
+	 * corresponding page is locked
+	 */
+	VM_WARN_ON_ONCE(softleaf_is_migration(entry) && !PageLocked(page));
+
+	return page;
+}
+
+/**
+ * softleaf_to_folio() - Obtains struct folio for PFN encoded within leaf entry.
+ * @entry: Leaf entry, softleaf_has_pfn(@entry) must return true.
+ *
+ * Returns: Pointer to the struct folio associated with the leaf entry's PFN.
+ */
+static inline struct folio *softleaf_to_folio(softleaf_t entry)
+{
+	struct folio *folio = pfn_folio(softleaf_to_pfn(entry));
+
+	VM_WARN_ON_ONCE(!softleaf_has_pfn(entry));
+	/*
+	 * Any use of migration entries may only occur while the
+	 * corresponding folio is locked.
+	 */
+	VM_WARN_ON_ONCE(softleaf_is_migration(entry) &&
+			!folio_test_locked(folio));
+
+	return folio;
+}
+
+/**
+ * softleaf_is_poison_marker() - Is this leaf entry a poison marker?
+ * @entry: Leaf entry.
+ *
+ * The poison marker is set via UFFDIO_POISON. Userfaultfd-specific.
+ *
+ * Returns: true if the leaf entry is a poison marker, otherwise false.
+ */
+static inline bool softleaf_is_poison_marker(softleaf_t entry)
+{
+	if (!softleaf_is_marker(entry))
+		return false;
+
+	return softleaf_to_marker(entry) & PTE_MARKER_POISONED;
+}
+
+/**
+ * softleaf_is_guard_marker() - Is this leaf entry a guard region marker?
+ * @entry: Leaf entry.
+ *
+ * Returns: true if the leaf entry is a guard marker, otherwise false.
+ */
+static inline bool softleaf_is_guard_marker(softleaf_t entry)
+{
+	if (!softleaf_is_marker(entry))
+		return false;
+
+	return softleaf_to_marker(entry) & PTE_MARKER_GUARD;
+}
+
+/**
+ * softleaf_is_uffd_wp_marker() - Is this leaf entry a userfautlfd write protect
+ * marker?
+ * @entry: Leaf entry.
+ *
+ * Userfaultfd-specific.
+ *
+ * Returns: true if the leaf entry is a UFFD WP marker, otherwise false.
+ */
+static inline bool softleaf_is_uffd_wp_marker(softleaf_t entry)
+{
+	if (!softleaf_is_marker(entry))
+		return false;
+
+	return softleaf_to_marker(entry) & PTE_MARKER_UFFD_WP;
+}
+
+#ifdef CONFIG_MIGRATION
+
+/**
+ * softleaf_is_migration_young() - Does this migration entry contain an accessed
+ * bit?
+ * @entry: Leaf entry.
+ *
+ * If the architecture can support storing A/D bits in migration entries, this
+ * determines whether the accessed (or 'young') bit was set on the migrated page
+ * table entry.
+ *
+ * Returns: true if the entry contains an accessed bit, otherwise false.
+ */
+static inline bool softleaf_is_migration_young(softleaf_t entry)
+{
+	VM_WARN_ON_ONCE(!softleaf_is_migration(entry));
+
+	if (migration_entry_supports_ad())
+		return swp_offset(entry) & SWP_MIG_YOUNG;
+	/* Keep the old behavior of aging page after migration */
+	return false;
+}
+
+/**
+ * softleaf_is_migration_dirty() - Does this migration entry contain a dirty bit?
+ * @entry: Leaf entry.
+ *
+ * If the architecture can support storing A/D bits in migration entries, this
+ * determines whether the dirty bit was set on the migrated page table entry.
+ *
+ * Returns: true if the entry contains a dirty bit, otherwise false.
+ */
+static inline bool softleaf_is_migration_dirty(softleaf_t entry)
+{
+	VM_WARN_ON_ONCE(!softleaf_is_migration(entry));
+
+	if (migration_entry_supports_ad())
+		return swp_offset(entry) & SWP_MIG_DIRTY;
+	/* Keep the old behavior of clean page after migration */
+	return false;
+}
+
+#else /* CONFIG_MIGRATION */
+
+static inline bool softleaf_is_migration_young(softleaf_t entry)
+{
+	return false;
+}
+
+static inline bool softleaf_is_migration_dirty(softleaf_t entry)
+{
+	return false;
+}
+#endif /* CONFIG_MIGRATION */
+
+/**
+ * pte_is_marker() - Does the PTE entry encode a marker leaf entry?
+ * @pte: PTE entry.
+ *
+ * Returns: true if this PTE is a marker leaf entry, otherwise false.
+ */
+static inline bool pte_is_marker(pte_t pte)
+{
+	return softleaf_is_marker(softleaf_from_pte(pte));
+}
+
+/**
+ * pte_is_uffd_wp_marker() - Does this PTE entry encode a userfaultfd write
+ * protect marker leaf entry?
+ * @pte: PTE entry.
+ *
+ * Returns: true if this PTE is a UFFD WP marker leaf entry, otherwise false.
+ */
+static inline bool pte_is_uffd_wp_marker(pte_t pte)
+{
+	const softleaf_t entry = softleaf_from_pte(pte);
+
+	return softleaf_is_uffd_wp_marker(entry);
+}
+
+/**
+ * pte_is_uffd_marker() - Does this PTE entry encode a userfault-specific marker
+ * leaf entry?
+ * @entry: Leaf entry.
+ *
+ * It's useful to be able to determine which leaf entries encode UFFD-specific
+ * markers so we can handle these correctly.
+ *
+ * Returns: true if this PTE entry is a UFFD-specific marker, otherwise false.
+ */
+static inline bool pte_is_uffd_marker(pte_t pte)
+{
+	const softleaf_t entry = softleaf_from_pte(pte);
+
+	if (!softleaf_is_marker(entry))
+		return false;
+
+	/* UFFD WP, poisoned swap entries are UFFD-handled. */
+	if (softleaf_is_uffd_wp_marker(entry))
+		return true;
+	if (softleaf_is_poison_marker(entry))
+		return true;
+
+	return false;
+}
+
+#if defined(CONFIG_ZONE_DEVICE) && defined(CONFIG_ARCH_ENABLE_THP_MIGRATION)
+
+/**
+ * pmd_is_device_private_entry() - Check if PMD contains a device private swap
+ * entry.
+ * @pmd: The PMD to check.
+ *
+ * Returns true if the PMD contains a swap entry that represents a device private
+ * page mapping. This is used for zone device private pages that have been
+ * swapped out but still need special handling during various memory management
+ * operations.
+ *
+ * Return: true if PMD contains device private entry, false otherwise
+ */
+static inline bool pmd_is_device_private_entry(pmd_t pmd)
+{
+	return softleaf_is_device_private(softleaf_from_pmd(pmd));
+}
+
+#else  /* CONFIG_ZONE_DEVICE && CONFIG_ARCH_ENABLE_THP_MIGRATION */
+
+static inline bool pmd_is_device_private_entry(pmd_t pmd)
+{
+	return false;
+}
+
+#endif /* CONFIG_ZONE_DEVICE && CONFIG_ARCH_ENABLE_THP_MIGRATION */
+
+/**
+ * pmd_is_migration_entry() - Does this PMD entry encode a migration entry?
+ * @pmd: PMD entry.
+ *
+ * Returns: true if the PMD encodes a migration entry, otherwise false.
+ */
+static inline bool pmd_is_migration_entry(pmd_t pmd)
+{
+	return softleaf_is_migration(softleaf_from_pmd(pmd));
+}
+
+/**
+ * pmd_is_valid_softleaf() - Is this PMD entry a valid leaf entry?
+ * @pmd: PMD entry.
+ *
+ * PMD leaf entries are valid only if they are device private or migration
+ * entries. This function asserts that a PMD leaf entry is valid in this
+ * respect.
+ *
+ * Returns: true if the PMD entry is a valid leaf entry, otherwise false.
+ */
+static inline bool pmd_is_valid_softleaf(pmd_t pmd)
+{
+	const softleaf_t entry = softleaf_from_pmd(pmd);
+
+	/* Only device private, migration entries valid for PMD. */
+	return softleaf_is_device_private(entry) ||
+		softleaf_is_migration(entry);
+}
+
+#endif  /* CONFIG_MMU */
+#endif  /* _LINUX_LEAFOPS_H */