include/linux/page_ext.h

Source file repositories/reference/linux-study-clean/include/linux/page_ext.h

File Facts

System
Linux kernel
Corpus path
include/linux/page_ext.h
Extension
.h
Size
5570 bytes
Lines
229
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

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)
{
}

static inline bool page_ext_iter_next_fast_possible(unsigned long next_pfn)
{
	/*
	 * page_ext is allocated per memory section. Once we cross a
	 * memory section, we have to fetch the new pointer.
	 */
	return next_pfn % PAGES_PER_SECTION;
}
#else
extern void page_ext_init_flatmem(void);
extern void page_ext_init_flatmem_late(void);
static inline void page_ext_init(void)
{
}

static inline bool page_ext_iter_next_fast_possible(unsigned long next_pfn)
{
	return true;
}
#endif

extern struct page_ext *page_ext_get(const struct page *page);
extern struct page_ext *page_ext_from_phys(phys_addr_t phys);
extern void page_ext_put(struct page_ext *page_ext);
extern struct page_ext *page_ext_lookup(unsigned long pfn);

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;
}

struct page_ext_iter {
	unsigned long index;

Annotation

Implementation Notes