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/* 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);
}
#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, pmd_t *pmd,
unsigned long address);
extern void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte);
#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, pmd_t *pmd,
unsigned long address) { }
static inline void migration_entry_wait_huge(struct vm_area_struct *vma,
pte_t *pte) { }
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 */
#ifdef CONFIG_MEMORY_FAILURE
/*
* 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;
}
#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;
}
#endif
typedef unsigned long pte_marker;
#define PTE_MARKER_UFFD_WP BIT(0)
/*
* "Poisoned" here is meant in the very general sense of "future accesses are
* invalid", instead of referring very specifically to hardware memory errors.
* This marker is meant to represent any of various different causes of this.
*/
#define PTE_MARKER_POISONED BIT(1)
#define PTE_MARKER_MASK (BIT(2) - 1)
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));
}
static inline pte_t make_pte_marker(pte_marker marker)
{
return swp_entry_to_pte(make_pte_marker_entry(marker));
}
static inline swp_entry_t make_poisoned_swp_entry(void)
{
return make_pte_marker_entry(PTE_MARKER_POISONED);
}
static inline int is_poisoned_swp_entry(swp_entry_t entry)
{
return is_pte_marker_entry(entry) &&
(pte_marker_get(entry) & PTE_MARKER_POISONED);
}
/*
* 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.
*/
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 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.
*/
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) || is_hwpoison_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 */
static inline int non_swap_entry(swp_entry_t entry)
{
return swp_type(entry) >= MAX_SWAPFILES;
}
#endif /* CONFIG_MMU */
#endif /* _LINUX_SWAPOPS_H */
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