mm.h

umon bootloader source code, support mips cpu.

 * Drop a ref, return true if the logical refcount fell to zero (the page has
 * no users)
 */
#define put_page_testzero(p)				\
	({						\
		BUG_ON(page_count(p) == 0);		\
		atomic_add_negative(-1, &(p)->_count);	\
	})

/*
 * Grab a ref, return true if the page previously had a logical refcount of
 * zero.  ie: returns true if we just grabbed an already-deemed-to-be-free page
 */
#define get_page_testone(p)	atomic_inc_and_test(&(p)->_count)

#define set_page_count(p,v) 	atomic_set(&(p)->_count, v - 1)
#define __put_page(p)		atomic_dec(&(p)->_count)

extern void FASTCALL(__page_cache_release(struct page *));

#ifdef CONFIG_HUGETLB_PAGE

static inline int page_count(struct page *p)
{
	if (PageCompound(p))
		p = (struct page *)p->private;
	return atomic_read(&(p)->_count) + 1;
}

static inline void get_page(struct page *page)
{
	if (unlikely(PageCompound(page)))
		page = (struct page *)page->private;
	atomic_inc(&page->_count);
}

void put_page(struct page *page);

#else		/* CONFIG_HUGETLB_PAGE */

#define page_count(p)		(atomic_read(&(p)->_count) + 1)

static inline void get_page(struct page *page)
{
	atomic_inc(&page->_count);
}

static inline void put_page(struct page *page)
{
	if (!PageReserved(page) && put_page_testzero(page))
		__page_cache_release(page);
}

#endif		/* CONFIG_HUGETLB_PAGE */

/*
 * Multiple processes may "see" the same page. E.g. for untouched
 * mappings of /dev/null, all processes see the same page full of
 * zeroes, and text pages of executables and shared libraries have
 * only one copy in memory, at most, normally.
 *
 * For the non-reserved pages, page_count(page) denotes a reference count.
 *   page_count() == 0 means the page is free.
 *   page_count() == 1 means the page is used for exactly one purpose
 *   (e.g. a private data page of one process).
 *
 * A page may be used for kmalloc() or anyone else who does a
 * __get_free_page(). In this case the page_count() is at least 1, and
 * all other fields are unused but should be 0 or NULL. The
 * management of this page is the responsibility of the one who uses
 * it.
 *
 * The other pages (we may call them "process pages") are completely
 * managed by the Linux memory manager: I/O, buffers, swapping etc.
 * The following discussion applies only to them.
 *
 * A page may belong to an inode's memory mapping. In this case,
 * page->mapping is the pointer to the inode, and page->index is the
 * file offset of the page, in units of PAGE_CACHE_SIZE.
 *
 * A page contains an opaque `private' member, which belongs to the
 * page's address_space.  Usually, this is the address of a circular
 * list of the page's disk buffers.
 *
 * For pages belonging to inodes, the page_count() is the number of
 * attaches, plus 1 if `private' contains something, plus one for
 * the page cache itself.
 *
 * All pages belonging to an inode are in these doubly linked lists:
 * mapping->clean_pages, mapping->dirty_pages and mapping->locked_pages;
 * using the page->list list_head. These fields are also used for
 * freelist managemet (when page_count()==0).
 *
 * There is also a per-mapping radix tree mapping index to the page
 * in memory if present. The tree is rooted at mapping->root.  
 *
 * All process pages can do I/O:
 * - inode pages may need to be read from disk,
 * - inode pages which have been modified and are MAP_SHARED may need
 *   to be written to disk,
 * - private pages which have been modified may need to be swapped out
 *   to swap space and (later) to be read back into memory.
 */

/*
 * The zone field is never updated after free_area_init_core()
 * sets it, so none of the operations on it need to be atomic.
 * We'll have up to (MAX_NUMNODES * MAX_NR_ZONES) zones total,
 * so we use (MAX_NODES_SHIFT + MAX_ZONES_SHIFT) here to get enough bits.
 */
#define NODEZONE_SHIFT (sizeof(page_flags_t)*8 - MAX_NODES_SHIFT - MAX_ZONES_SHIFT)
#define NODEZONE(node, zone)	((node << ZONES_SHIFT) | zone)

static inline unsigned long page_zonenum(struct page *page)
{
	return (page->flags >> NODEZONE_SHIFT) & (~(~0UL << ZONES_SHIFT));
}
static inline unsigned long page_to_nid(struct page *page)
{
	return (page->flags >> (NODEZONE_SHIFT + ZONES_SHIFT));
}

struct zone;
extern struct zone *zone_table[];

static inline struct zone *page_zone(struct page *page)
{
	return zone_table[page->flags >> NODEZONE_SHIFT];
}

static inline void set_page_zone(struct page *page, unsigned long nodezone_num)
{
	page->flags &= ~(~0UL << NODEZONE_SHIFT);
	page->flags |= nodezone_num << NODEZONE_SHIFT;
}

#ifndef CONFIG_DISCONTIGMEM
/* The array of struct pages - for discontigmem use pgdat->lmem_map */
extern struct page *mem_map;
#endif

static inline void *lowmem_page_address(struct page *page)
{
	return __va(page_to_pfn(page) << PAGE_SHIFT);
}

#if defined(CONFIG_HIGHMEM) && !defined(WANT_PAGE_VIRTUAL)
#define HASHED_PAGE_VIRTUAL
#endif

#if defined(WANT_PAGE_VIRTUAL)
#define page_address(page) ((page)->virtual)
#define set_page_address(page, address)			\
	do {						\
		(page)->virtual = (address);		\
	} while(0)
#define page_address_init()  do { } while(0)
#endif

#if defined(HASHED_PAGE_VIRTUAL)
void *page_address(struct page *page);
void set_page_address(struct page *page, void *virtual);
void page_address_init(void);
#endif

#if !defined(HASHED_PAGE_VIRTUAL) && !defined(WANT_PAGE_VIRTUAL)
#define page_address(page) lowmem_page_address(page)
#define set_page_address(page, address)  do { } while(0)
#define page_address_init()  do { } while(0)
#endif

/*
 * On an anonymous page mapped into a user virtual memory area,
 * page->mapping points to its anon_vma, not to a struct address_space;
 * with the PAGE_MAPPING_ANON bit set to distinguish it.
 *
 * Please note that, confusingly, "page_mapping" refers to the inode
 * address_space which maps the page from disk; whereas "page_mapped"
 * refers to user virtual address space into which the page is mapped.
 */
#define PAGE_MAPPING_ANON	1

extern struct address_space swapper_space;
static inline struct address_space *page_mapping(struct page *page)
{
	struct address_space *mapping = page->mapping;

	if (unlikely(PageSwapCache(page)))
		mapping = &swapper_space;
	else if (unlikely((unsigned long)mapping & PAGE_MAPPING_ANON))
		mapping = NULL;
	return mapping;
}

static inline int PageAnon(struct page *page)
{
	return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
}

/*
 * Return the pagecache index of the passed page.  Regular pagecache pages
 * use ->index whereas swapcache pages use ->private
 */
static inline pgoff_t page_index(struct page *page)
{
	if (unlikely(PageSwapCache(page)))
		return page->private;
	return page->index;
}

/*
 * The atomic page->_mapcount, like _count, starts from -1:
 * so that transitions both from it and to it can be tracked,
 * using atomic_inc_and_test and atomic_add_negative(-1).
 */
static inline void reset_page_mapcount(struct page *page)
{
	atomic_set(&(page)->_mapcount, -1);
}

static inline int page_mapcount(struct page *page)
{
	return atomic_read(&(page)->_mapcount) + 1;
}

/*
 * Return true if this page is mapped into pagetables.
 */
static inline int page_mapped(struct page *page)
{
	return atomic_read(&(page)->_mapcount) >= 0;
}

/*
 * Error return values for the *_nopage functions
 */
#define NOPAGE_SIGBUS	(NULL)
#define NOPAGE_OOM	((struct page *) (-1))

/*
 * Different kinds of faults, as returned by handle_mm_fault().
 * Used to decide whether a process gets delivered SIGBUS or
 * just gets major/minor fault counters bumped up.
 */
#define VM_FAULT_OOM	(-1)
#define VM_FAULT_SIGBUS	0
#define VM_FAULT_MINOR	1
#define VM_FAULT_MAJOR	2

#define offset_in_page(p)	((unsigned long)(p) & ~PAGE_MASK)

extern void show_free_areas(void);

#ifdef CONFIG_SHMEM
struct page *shmem_nopage(struct vm_area_struct *vma,
			unsigned long address, int *type);
int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new);
struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
					unsigned long addr);
int shmem_lock(struct file *file, int lock, struct user_struct *user);
#else
#define shmem_nopage filemap_nopage
#define shmem_lock(a, b, c) 	({0;})	/* always in memory, no need to lock */
#define shmem_set_policy(a, b)	(0)
#define shmem_get_policy(a, b)	(NULL)
#endif
struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags);

int shmem_zero_setup(struct vm_area_struct *);

static inline int can_do_mlock(void)
{
	if (capable(CAP_IPC_LOCK))
		return 1;
	if (current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur != 0)
		return 1;
	return 0;
}
extern int user_shm_lock(size_t, struct user_struct *);
extern void user_shm_unlock(size_t, struct user_struct *);

/*
 * Parameter block passed down to zap_pte_range in exceptional cases.
 */
struct zap_details {
	struct vm_area_struct *nonlinear_vma;	/* Check page->index if set */
	struct address_space *check_mapping;	/* Check page->mapping if set */
	pgoff_t	first_index;			/* Lowest page->index to unmap */
	pgoff_t last_index;			/* Highest page->index to unmap */
	spinlock_t *i_mmap_lock;		/* For unmap_mapping_range: */