diff options
Diffstat (limited to 'kernel/include/linux/swapops.h')
-rw-r--r-- | kernel/include/linux/swapops.h | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/kernel/include/linux/swapops.h b/kernel/include/linux/swapops.h new file mode 100644 index 000000000..cedf3d3c3 --- /dev/null +++ b/kernel/include/linux/swapops.h @@ -0,0 +1,205 @@ +#ifndef _LINUX_SWAPOPS_H +#define _LINUX_SWAPOPS_H + +#include <linux/radix-tree.h> +#include <linux/bug.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); +} + +#ifdef CONFIG_MIGRATION +static inline swp_entry_t make_migration_entry(struct page *page, int write) +{ + BUG_ON(!PageLocked(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 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(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; +} +#define migration_entry_to_page(swp) 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 + +#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 + +#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION) +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 */ |