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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_PAGE_EXT_H
#define __LINUX_PAGE_EXT_H
#include <linux/types.h>
#include <linux/stacktrace.h>
struct pglist_data;
#ifdef CONFIG_PAGE_EXTENSION
/**
* struct page_ext_operations - per page_ext client operations
* @offset: Offset to the client's data within page_ext. Offset is returned to
* the client by page_ext_init.
* @size: The size of the client data within page_ext.
* @need: Function that returns true if client requires page_ext.
* @init: (optional) Called to initialize client once page_exts are allocated.
* @need_shared_flags: True when client is using shared page_ext->flags
* field.
*
* Each Page Extension client must define page_ext_operations in
* page_ext_ops array.
*/
struct page_ext_operations {
size_t offset;
size_t size;
bool (*need)(void);
void (*init)(void);
bool need_shared_flags;
};
/*
* The page_ext_flags users must set need_shared_flags to true.
*/
enum page_ext_flags {
PAGE_EXT_OWNER,
PAGE_EXT_OWNER_ALLOCATED,
#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
PAGE_EXT_YOUNG,
PAGE_EXT_IDLE,
#endif
};
/*
* Page Extension can be considered as an extended mem_map.
* A page_ext page is associated with every page descriptor. The
* page_ext helps us add more information about the page.
* All page_ext are allocated at boot or memory hotplug event,
* then the page_ext for pfn always exists.
*/
struct page_ext {
unsigned long flags;
};
extern bool early_page_ext;
extern unsigned long page_ext_size;
extern void pgdat_page_ext_init(struct pglist_data *pgdat);
static inline bool early_page_ext_enabled(void)
{
return early_page_ext;
}
#ifdef CONFIG_SPARSEMEM
static inline void page_ext_init_flatmem(void)
{
}
extern void page_ext_init(void);
static inline void page_ext_init_flatmem_late(void)
{
}
#else
extern void page_ext_init_flatmem(void);
extern void page_ext_init_flatmem_late(void);
static inline void page_ext_init(void)
{
}
#endif
extern struct page_ext *page_ext_get(const struct page *page);
extern void page_ext_put(struct page_ext *page_ext);
static inline void *page_ext_data(struct page_ext *page_ext,
struct page_ext_operations *ops)
{
return (void *)(page_ext) + ops->offset;
}
static inline struct page_ext *page_ext_next(struct page_ext *curr)
{
void *next = curr;
next += page_ext_size;
return next;
}
#else /* !CONFIG_PAGE_EXTENSION */
struct page_ext;
static inline bool early_page_ext_enabled(void)
{
return false;
}
static inline void pgdat_page_ext_init(struct pglist_data *pgdat)
{
}
static inline void page_ext_init(void)
{
}
static inline void page_ext_init_flatmem_late(void)
{
}
static inline void page_ext_init_flatmem(void)
{
}
static inline struct page_ext *page_ext_get(const struct page *page)
{
return NULL;
}
static inline void page_ext_put(struct page_ext *page_ext)
{
}
#endif /* CONFIG_PAGE_EXTENSION */
#endif /* __LINUX_PAGE_EXT_H */
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