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/include/linux/swapops.h

https://github.com/airy09/android_kernel_sony_apq8064
C Header | 195 lines | 128 code | 29 blank | 38 comment | 7 complexity | cb20e697154ded5742648811967db2c4 MD5 | raw file
  1#ifndef _LINUX_SWAPOPS_H
  2#define _LINUX_SWAPOPS_H
  3
  4#include <linux/radix-tree.h>
  5#include <linux/bug.h>
  6
  7/*
  8 * swapcache pages are stored in the swapper_space radix tree.  We want to
  9 * get good packing density in that tree, so the index should be dense in
 10 * the low-order bits.
 11 *
 12 * We arrange the `type' and `offset' fields so that `type' is at the five
 13 * high-order bits of the swp_entry_t and `offset' is right-aligned in the
 14 * remaining bits.
 15 *
 16 * swp_entry_t's are *never* stored anywhere in their arch-dependent format.
 17 */
 18#define SWP_TYPE_SHIFT(e)	(sizeof(e.val) * 8 - MAX_SWAPFILES_SHIFT)
 19#define SWP_OFFSET_MASK(e)	((1UL << SWP_TYPE_SHIFT(e)) - 1)
 20
 21/*
 22 * Store a type+offset into a swp_entry_t in an arch-independent format
 23 */
 24static inline swp_entry_t swp_entry(unsigned long type, pgoff_t offset)
 25{
 26	swp_entry_t ret;
 27
 28	ret.val = (type << SWP_TYPE_SHIFT(ret)) |
 29			(offset & SWP_OFFSET_MASK(ret));
 30	return ret;
 31}
 32
 33/*
 34 * Extract the `type' field from a swp_entry_t.  The swp_entry_t is in
 35 * arch-independent format
 36 */
 37static inline unsigned swp_type(swp_entry_t entry)
 38{
 39	return (entry.val >> SWP_TYPE_SHIFT(entry));
 40}
 41
 42/*
 43 * Extract the `offset' field from a swp_entry_t.  The swp_entry_t is in
 44 * arch-independent format
 45 */
 46static inline pgoff_t swp_offset(swp_entry_t entry)
 47{
 48	return entry.val & SWP_OFFSET_MASK(entry);
 49}
 50
 51#ifdef CONFIG_MMU
 52/* check whether a pte points to a swap entry */
 53static inline int is_swap_pte(pte_t pte)
 54{
 55	return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
 56}
 57#endif
 58
 59/*
 60 * Convert the arch-dependent pte representation of a swp_entry_t into an
 61 * arch-independent swp_entry_t.
 62 */
 63static inline swp_entry_t pte_to_swp_entry(pte_t pte)
 64{
 65	swp_entry_t arch_entry;
 66
 67	BUG_ON(pte_file(pte));
 68	arch_entry = __pte_to_swp_entry(pte);
 69	return swp_entry(__swp_type(arch_entry), __swp_offset(arch_entry));
 70}
 71
 72/*
 73 * Convert the arch-independent representation of a swp_entry_t into the
 74 * arch-dependent pte representation.
 75 */
 76static inline pte_t swp_entry_to_pte(swp_entry_t entry)
 77{
 78	swp_entry_t arch_entry;
 79
 80	arch_entry = __swp_entry(swp_type(entry), swp_offset(entry));
 81	BUG_ON(pte_file(__swp_entry_to_pte(arch_entry)));
 82	return __swp_entry_to_pte(arch_entry);
 83}
 84
 85static inline swp_entry_t radix_to_swp_entry(void *arg)
 86{
 87	swp_entry_t entry;
 88
 89	entry.val = (unsigned long)arg >> RADIX_TREE_EXCEPTIONAL_SHIFT;
 90	return entry;
 91}
 92
 93static inline void *swp_to_radix_entry(swp_entry_t entry)
 94{
 95	unsigned long value;
 96
 97	value = entry.val << RADIX_TREE_EXCEPTIONAL_SHIFT;
 98	return (void *)(value | RADIX_TREE_EXCEPTIONAL_ENTRY);
 99}
100
101#ifdef CONFIG_MIGRATION
102static inline swp_entry_t make_migration_entry(struct page *page, int write)
103{
104	BUG_ON(!PageLocked(page));
105	return swp_entry(write ? SWP_MIGRATION_WRITE : SWP_MIGRATION_READ,
106			page_to_pfn(page));
107}
108
109static inline int is_migration_entry(swp_entry_t entry)
110{
111	return unlikely(swp_type(entry) == SWP_MIGRATION_READ ||
112			swp_type(entry) == SWP_MIGRATION_WRITE);
113}
114
115static inline int is_write_migration_entry(swp_entry_t entry)
116{
117	return unlikely(swp_type(entry) == SWP_MIGRATION_WRITE);
118}
119
120static inline struct page *migration_entry_to_page(swp_entry_t entry)
121{
122	struct page *p = pfn_to_page(swp_offset(entry));
123	/*
124	 * Any use of migration entries may only occur while the
125	 * corresponding page is locked
126	 */
127	BUG_ON(!PageLocked(p));
128	return p;
129}
130
131static inline void make_migration_entry_read(swp_entry_t *entry)
132{
133	*entry = swp_entry(SWP_MIGRATION_READ, swp_offset(*entry));
134}
135
136extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
137					unsigned long address);
138#else
139
140#define make_migration_entry(page, write) swp_entry(0, 0)
141static inline int is_migration_entry(swp_entry_t swp)
142{
143	return 0;
144}
145#define migration_entry_to_page(swp) NULL
146static inline void make_migration_entry_read(swp_entry_t *entryp) { }
147static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
148					 unsigned long address) { }
149static inline int is_write_migration_entry(swp_entry_t entry)
150{
151	return 0;
152}
153
154#endif
155
156#ifdef CONFIG_MEMORY_FAILURE
157/*
158 * Support for hardware poisoned pages
159 */
160static inline swp_entry_t make_hwpoison_entry(struct page *page)
161{
162	BUG_ON(!PageLocked(page));
163	return swp_entry(SWP_HWPOISON, page_to_pfn(page));
164}
165
166static inline int is_hwpoison_entry(swp_entry_t entry)
167{
168	return swp_type(entry) == SWP_HWPOISON;
169}
170#else
171
172static inline swp_entry_t make_hwpoison_entry(struct page *page)
173{
174	return swp_entry(0, 0);
175}
176
177static inline int is_hwpoison_entry(swp_entry_t swp)
178{
179	return 0;
180}
181#endif
182
183#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
184static inline int non_swap_entry(swp_entry_t entry)
185{
186	return swp_type(entry) >= MAX_SWAPFILES;
187}
188#else
189static inline int non_swap_entry(swp_entry_t entry)
190{
191	return 0;
192}
193#endif
194
195#endif /* _LINUX_SWAPOPS_H */