diff options
Diffstat (limited to 'include/linux/swapops.h')
| -rw-r--r-- | include/linux/swapops.h | 639 |
1 files changed, 639 insertions, 0 deletions
diff --git a/include/linux/swapops.h b/include/linux/swapops.h new file mode 100644 index 000000000..b07b277d6 --- /dev/null +++ b/include/linux/swapops.h @@ -0,0 +1,639 @@ +/* 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> + +#ifdef CONFIG_MMU + +#ifdef CONFIG_SWAP +#include <linux/swapfile.h> +#endif /* CONFIG_SWAP */ + +/* + * 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 six + * 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 one bit: see swp_to_radix_entry(). + * + * swp_entry_t's are *never* stored anywhere in their arch-dependent format. + */ +#define SWP_TYPE_SHIFT (BITS_PER_XA_VALUE - MAX_SWAPFILES_SHIFT) +#define SWP_OFFSET_MASK ((1UL << SWP_TYPE_SHIFT) - 1) + +/* + * Definitions only for PFN swap entries (see is_pfn_swap_entry()). To + * store PFN, we only need SWP_PFN_BITS bits. Each of the pfn swap entries + * can use the extra bits to store other information besides PFN. + */ +#ifdef MAX_PHYSMEM_BITS +#define SWP_PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT) +#else /* MAX_PHYSMEM_BITS */ +#define SWP_PFN_BITS min_t(int, \ + sizeof(phys_addr_t) * 8 - PAGE_SHIFT, \ + SWP_TYPE_SHIFT) +#endif /* MAX_PHYSMEM_BITS */ +#define SWP_PFN_MASK (BIT(SWP_PFN_BITS) - 1) + +/** + * Migration swap entry specific bitfield definitions. Layout: + * + * |----------+--------------------| + * | swp_type | swp_offset | + * |----------+--------+-+-+-------| + * | | resv |D|A| PFN | + * |----------+--------+-+-+-------| + * + * @SWP_MIG_YOUNG_BIT: Whether the page used to have young bit set (bit A) + * @SWP_MIG_DIRTY_BIT: Whether the page used to have dirty bit set (bit D) + * + * Note: A/D bits will be stored in migration entries iff there're enough + * free bits in arch specific swp offset. By default we'll ignore A/D bits + * when migrating a page. Please refer to migration_entry_supports_ad() + * for more information. If there're more bits besides PFN and A/D bits, + * they should be reserved and always be zeros. + */ +#define SWP_MIG_YOUNG_BIT (SWP_PFN_BITS) +#define SWP_MIG_DIRTY_BIT (SWP_PFN_BITS + 1) +#define SWP_MIG_TOTAL_BITS (SWP_PFN_BITS + 2) + +#define SWP_MIG_YOUNG BIT(SWP_MIG_YOUNG_BIT) +#define SWP_MIG_DIRTY BIT(SWP_MIG_DIRTY_BIT) + +static inline bool is_pfn_swap_entry(swp_entry_t entry); + +/* Clear all flags but only keep swp_entry_t related information */ +static inline pte_t pte_swp_clear_flags(pte_t pte) +{ + if (pte_swp_exclusive(pte)) + pte = pte_swp_clear_exclusive(pte); + if (pte_swp_soft_dirty(pte)) + pte = pte_swp_clear_soft_dirty(pte); + if (pte_swp_uffd_wp(pte)) + pte = pte_swp_clear_uffd_wp(pte); + return pte; +} + +/* + * 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) | (offset & SWP_OFFSET_MASK); + 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); +} + +/* + * 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; +} + +/* + * This should only be called upon a pfn swap entry to get the PFN stored + * in the swap entry. Please refers to is_pfn_swap_entry() for definition + * of pfn swap entry. + */ +static inline unsigned long swp_offset_pfn(swp_entry_t entry) +{ + VM_BUG_ON(!is_pfn_swap_entry(entry)); + return swp_offset(entry) & SWP_PFN_MASK; +} + +/* 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); +} + +/* + * 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; + + pte = pte_swp_clear_flags(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 = xa_to_value(arg); + return entry; +} + +static inline void *swp_to_radix_entry(swp_entry_t entry) +{ + return xa_mk_value(entry.val); +} + +static inline swp_entry_t make_swapin_error_entry(struct page *page) +{ + return swp_entry(SWP_SWAPIN_ERROR, page_to_pfn(page)); +} + +static inline int is_swapin_error_entry(swp_entry_t entry) +{ + return swp_type(entry) == SWP_SWAPIN_ERROR; +} + +#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) +static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset) +{ + return swp_entry(SWP_DEVICE_READ, offset); +} + +static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset) +{ + return swp_entry(SWP_DEVICE_WRITE, offset); +} + +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 bool is_writable_device_private_entry(swp_entry_t entry) +{ + return unlikely(swp_type(entry) == SWP_DEVICE_WRITE); +} + +static inline swp_entry_t make_readable_device_exclusive_entry(pgoff_t offset) +{ + return swp_entry(SWP_DEVICE_EXCLUSIVE_READ, offset); +} + +static inline swp_entry_t make_writable_device_exclusive_entry(pgoff_t offset) +{ + return swp_entry(SWP_DEVICE_EXCLUSIVE_WRITE, offset); +} + +static inline bool is_device_exclusive_entry(swp_entry_t entry) +{ + return swp_type(entry) == SWP_DEVICE_EXCLUSIVE_READ || + swp_type(entry) == SWP_DEVICE_EXCLUSIVE_WRITE; +} + +static inline bool is_writable_device_exclusive_entry(swp_entry_t entry) +{ + return unlikely(swp_type(entry) == SWP_DEVICE_EXCLUSIVE_WRITE); +} +#else /* CONFIG_DEVICE_PRIVATE */ +static inline swp_entry_t make_readable_device_private_entry(pgoff_t offset) +{ + return swp_entry(0, 0); +} + +static inline swp_entry_t make_writable_device_private_entry(pgoff_t offset) +{ + return swp_entry(0, 0); +} + +static inline bool is_device_private_entry(swp_entry_t entry) +{ + return false; +} + +static inline bool is_writable_device_private_entry(swp_entry_t entry) +{ + return false; +} + +static inline swp_entry_t make_readable_device_exclusive_entry(pgoff_t offset) +{ + return swp_entry(0, 0); +} + +static inline swp_entry_t make_writable_device_exclusive_entry(pgoff_t offset) +{ + return swp_entry(0, 0); +} + +static inline bool is_device_exclusive_entry(swp_entry_t entry) +{ + return false; +} + +static inline bool is_writable_device_exclusive_entry(swp_entry_t entry) +{ + return false; +} +#endif /* CONFIG_DEVICE_PRIVATE */ + +#ifdef CONFIG_MIGRATION +static inline int is_migration_entry(swp_entry_t entry) +{ + return unlikely(swp_type(entry) == SWP_MIGRATION_READ || + swp_type(entry) == SWP_MIGRATION_READ_EXCLUSIVE || + swp_type(entry) == SWP_MIGRATION_WRITE); +} + +static inline int is_writable_migration_entry(swp_entry_t entry) +{ + return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE); +} + +static inline int is_readable_migration_entry(swp_entry_t entry) +{ + return unlikely(swp_type(entry) == SWP_MIGRATION_READ); +} + +static inline int is_readable_exclusive_migration_entry(swp_entry_t entry) +{ + return unlikely(swp_type(entry) == SWP_MIGRATION_READ_EXCLUSIVE); +} + +static inline swp_entry_t make_readable_migration_entry(pgoff_t offset) +{ + return swp_entry(SWP_MIGRATION_READ, offset); +} + +static inline swp_entry_t make_readable_exclusive_migration_entry(pgoff_t offset) +{ + return swp_entry(SWP_MIGRATION_READ_EXCLUSIVE, offset); +} + +static inline swp_entry_t make_writable_migration_entry(pgoff_t offset) +{ + return swp_entry(SWP_MIGRATION_WRITE, offset); +} + +/* + * Returns whether the host has large enough swap offset field to support + * carrying over pgtable A/D bits for page migrations. The result is + * pretty much arch specific. + */ +static inline bool migration_entry_supports_ad(void) +{ +#ifdef CONFIG_SWAP + return swap_migration_ad_supported; +#else /* CONFIG_SWAP */ + return false; +#endif /* CONFIG_SWAP */ +} + +static inline swp_entry_t make_migration_entry_young(swp_entry_t entry) +{ + if (migration_entry_supports_ad()) + return swp_entry(swp_type(entry), + swp_offset(entry) | SWP_MIG_YOUNG); + return entry; +} + +static inline bool is_migration_entry_young(swp_entry_t entry) +{ + if (migration_entry_supports_ad()) + return swp_offset(entry) & SWP_MIG_YOUNG; + /* Keep the old behavior of aging page after migration */ + return false; +} + +static inline swp_entry_t make_migration_entry_dirty(swp_entry_t entry) +{ + if (migration_entry_supports_ad()) + return swp_entry(swp_type(entry), + swp_offset(entry) | SWP_MIG_DIRTY); + return entry; +} + +static inline bool is_migration_entry_dirty(swp_entry_t entry) +{ + if (migration_entry_supports_ad()) + return swp_offset(entry) & SWP_MIG_DIRTY; + /* Keep the old behavior of clean page after migration */ + return false; +} + +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); +#ifdef CONFIG_HUGETLB_PAGE +extern void __migration_entry_wait_huge(pte_t *ptep, spinlock_t *ptl); +extern void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte); +#endif /* CONFIG_HUGETLB_PAGE */ +#else /* CONFIG_MIGRATION */ +static inline swp_entry_t make_readable_migration_entry(pgoff_t offset) +{ + return swp_entry(0, 0); +} + +static inline swp_entry_t make_readable_exclusive_migration_entry(pgoff_t offset) +{ + return swp_entry(0, 0); +} + +static inline swp_entry_t make_writable_migration_entry(pgoff_t offset) +{ + return swp_entry(0, 0); +} + +static inline int is_migration_entry(swp_entry_t swp) +{ + return 0; +} + +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) { } +#ifdef CONFIG_HUGETLB_PAGE +static inline void __migration_entry_wait_huge(pte_t *ptep, spinlock_t *ptl) { } +static inline void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte) { } +#endif /* CONFIG_HUGETLB_PAGE */ +static inline int is_writable_migration_entry(swp_entry_t entry) +{ + return 0; +} +static inline int is_readable_migration_entry(swp_entry_t entry) +{ + return 0; +} + +static inline swp_entry_t make_migration_entry_young(swp_entry_t entry) +{ + return entry; +} + +static inline bool is_migration_entry_young(swp_entry_t entry) +{ + return false; +} + +static inline swp_entry_t make_migration_entry_dirty(swp_entry_t entry) +{ + return entry; +} + +static inline bool is_migration_entry_dirty(swp_entry_t entry) +{ + return false; +} +#endif /* CONFIG_MIGRATION */ + +typedef unsigned long pte_marker; + +#define PTE_MARKER_UFFD_WP BIT(0) +#define PTE_MARKER_MASK (PTE_MARKER_UFFD_WP) + +#ifdef CONFIG_PTE_MARKER + +static inline swp_entry_t make_pte_marker_entry(pte_marker marker) +{ + return swp_entry(SWP_PTE_MARKER, marker); +} + +static inline bool is_pte_marker_entry(swp_entry_t entry) +{ + return swp_type(entry) == SWP_PTE_MARKER; +} + +static inline pte_marker pte_marker_get(swp_entry_t entry) +{ + return swp_offset(entry) & PTE_MARKER_MASK; +} + +static inline bool is_pte_marker(pte_t pte) +{ + return is_swap_pte(pte) && is_pte_marker_entry(pte_to_swp_entry(pte)); +} + +#else /* CONFIG_PTE_MARKER */ + +static inline swp_entry_t make_pte_marker_entry(pte_marker marker) +{ + /* This should never be called if !CONFIG_PTE_MARKER */ + WARN_ON_ONCE(1); + return swp_entry(0, 0); +} + +static inline bool is_pte_marker_entry(swp_entry_t entry) +{ + return false; +} + +static inline pte_marker pte_marker_get(swp_entry_t entry) +{ + return 0; +} + +static inline bool is_pte_marker(pte_t pte) +{ + return false; +} + +#endif /* CONFIG_PTE_MARKER */ + +static inline pte_t make_pte_marker(pte_marker marker) +{ + return swp_entry_to_pte(make_pte_marker_entry(marker)); +} + +/* + * This is a special version to check pte_none() just to cover the case when + * the pte is a pte marker. It existed because in many cases the pte marker + * should be seen as a none pte; it's just that we have stored some information + * onto the none pte so it becomes not-none any more. + * + * It should be used when the pte is file-backed, ram-based and backing + * userspace pages, like shmem. It is not needed upon pgtables that do not + * support pte markers at all. For example, it's not needed on anonymous + * memory, kernel-only memory (including when the system is during-boot), + * non-ram based generic file-system. It's fine to be used even there, but the + * extra pte marker check will be pure overhead. + * + * For systems configured with !CONFIG_PTE_MARKER this will be automatically + * optimized to pte_none(). + */ +static inline int pte_none_mostly(pte_t pte) +{ + return pte_none(pte) || is_pte_marker(pte); +} + +static inline struct page *pfn_swap_entry_to_page(swp_entry_t entry) +{ + struct page *p = pfn_to_page(swp_offset_pfn(entry)); + + /* + * Any use of migration entries may only occur while the + * corresponding page is locked + */ + BUG_ON(is_migration_entry(entry) && !PageLocked(p)); + + return p; +} + +/* + * A pfn swap entry is a special type of swap entry that always has a pfn stored + * in the swap offset. They are used to represent unaddressable device memory + * and to restrict access to a page undergoing migration. + */ +static inline bool is_pfn_swap_entry(swp_entry_t entry) +{ + /* Make sure the swp offset can always store the needed fields */ + BUILD_BUG_ON(SWP_TYPE_SHIFT < SWP_PFN_BITS); + + return is_migration_entry(entry) || is_device_private_entry(entry) || + is_device_exclusive_entry(entry); +} + +struct page_vma_mapped_walk; + +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION +extern int 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); + if (pmd_swp_uffd_wp(pmd)) + pmd = pmd_swp_clear_uffd_wp(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 is_swap_pmd(pmd) && is_migration_entry(pmd_to_swp_entry(pmd)); +} +#else /* CONFIG_ARCH_ENABLE_THP_MIGRATION */ +static inline int 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 /* CONFIG_ARCH_ENABLE_THP_MIGRATION */ + +#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_sub(long i) +{ + atomic_long_sub(i, &num_poisoned_pages); +} + +#else /* CONFIG_MEMORY_FAILURE */ + +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) +{ +} + +static inline void num_poisoned_pages_sub(long i) +{ +} +#endif /* CONFIG_MEMORY_FAILURE */ + +static inline int non_swap_entry(swp_entry_t entry) +{ + return swp_type(entry) >= MAX_SWAPFILES; +} + +#endif /* CONFIG_MMU */ +#endif /* _LINUX_SWAPOPS_H */ |