mm.h

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#ifndef _LINUX_MM_H
#define _LINUX_MM_H

#include <linux/sched.h>
#include <linux/errno.h>

#ifdef __KERNEL__

#include <linux/config.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/mmzone.h>

extern unsigned long max_mapnr;
extern unsigned long num_physpages;
extern void * high_memory;
extern int page_cluster;
/* The inactive_clean lists are per zone. */
extern struct list_head active_list;
extern struct list_head inactive_dirty_list;

#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/atomic.h>

/*
 * Linux kernel virtual memory manager primitives.
 * The idea being to have a "virtual" mm in the same way
 * we have a virtual fs - giving a cleaner interface to the
 * mm details, and allowing different kinds of memory mappings
 * (from shared memory to executable loading to arbitrary
 * mmap() functions).
 */

/*
 * This struct defines a memory VMM memory area. There is one of these
 * per VM-area/task.  A VM area is any part of the process virtual memory
 * space that has a special rule for the page-fault handlers (ie a shared
 * library, the executable area etc).
 */
struct vm_area_struct {
	struct mm_struct * vm_mm;	/* VM area parameters */
	unsigned long vm_start;
	unsigned long vm_end;

	/* linked list of VM areas per task, sorted by address */
	struct vm_area_struct *vm_next;

	pgprot_t vm_page_prot;
	unsigned long vm_flags;

	/* AVL tree of VM areas per task, sorted by address */
	short vm_avl_height;
	struct vm_area_struct * vm_avl_left;
	struct vm_area_struct * vm_avl_right;

	/* For areas with an address space and backing store,
	 * one of the address_space->i_mmap{,shared} lists,
	 * for shm areas, the list of attaches, otherwise unused.
	 */
	struct vm_area_struct *vm_next_share;
	struct vm_area_struct **vm_pprev_share;

	struct vm_operations_struct * vm_ops;
	unsigned long vm_pgoff;		/* offset in PAGE_SIZE units, *not* PAGE_CACHE_SIZE */
	struct file * vm_file;
	unsigned long vm_raend;
	void * vm_private_data;		/* was vm_pte (shared mem) */
};

/*
 * vm_flags..
 */
#define VM_READ		0x00000001	/* currently active flags */
#define VM_WRITE	0x00000002
#define VM_EXEC		0x00000004
#define VM_SHARED	0x00000008

#define VM_MAYREAD	0x00000010	/* limits for mprotect() etc */
#define VM_MAYWRITE	0x00000020
#define VM_MAYEXEC	0x00000040
#define VM_MAYSHARE	0x00000080

#define VM_GROWSDOWN	0x00000100	/* general info on the segment */
#define VM_GROWSUP	0x00000200
#define VM_SHM		0x00000400	/* shared memory area, don't swap out */
#define VM_DENYWRITE	0x00000800	/* ETXTBSY on write attempts.. */

#define VM_EXECUTABLE	0x00001000
#define VM_LOCKED	0x00002000
#define VM_IO           0x00004000	/* Memory mapped I/O or similar */

#define VM_SEQ_READ	0x00008000	/* App will access data sequentially */
#define VM_RAND_READ	0x00010000	/* App will not benefit from clustered reads */

#define VM_DONTCOPY	0x00020000      /* Do not copy this vma on fork */
#define VM_DONTEXPAND	0x00040000	/* Cannot expand with mremap() */
#define VM_RESERVED	0x00080000	/* Don't unmap it from swap_out */

#define VM_STACK_FLAGS	0x00000177

#define VM_READHINTMASK			(VM_SEQ_READ | VM_RAND_READ)
#define VM_ClearReadHint(v)		(v)->vm_flags &= ~VM_READHINTMASK
#define VM_NormalReadHint(v)		(!((v)->vm_flags & VM_READHINTMASK))
#define VM_SequentialReadHint(v)	((v)->vm_flags & VM_SEQ_READ)
#define VM_RandomReadHint(v)		((v)->vm_flags & VM_RAND_READ)

/*
 * mapping from the currently active vm_flags protection bits (the
 * low four bits) to a page protection mask..
 */
extern pgprot_t protection_map[16];


/*
 * These are the virtual MM functions - opening of an area, closing and
 * unmapping it (needed to keep files on disk up-to-date etc), pointer
 * to the functions called when a no-page or a wp-page exception occurs. 
 */
struct vm_operations_struct {
	void (*open)(struct vm_area_struct * area);
	void (*close)(struct vm_area_struct * area);
	struct page * (*nopage)(struct vm_area_struct * area, unsigned long address, int write_access);
};

/*
 * Try to keep the most commonly accessed fields in single cache lines
 * here (16 bytes or greater).  This ordering should be particularly
 * beneficial on 32-bit processors.
 *
 * The first line is data used in page cache lookup, the second line
 * is used for linear searches (eg. clock algorithm scans). 
 */
typedef struct page {
	struct list_head list;
	struct address_space *mapping;
	unsigned long index;
	struct page *next_hash;
	atomic_t count;
	unsigned long flags;	/* atomic flags, some possibly updated asynchronously */
	struct list_head lru;
	unsigned long age;
	wait_queue_head_t wait;
	struct page **pprev_hash;
	struct buffer_head * buffers;
	void *virtual; /* non-NULL if kmapped */
	struct zone_struct *zone;
} mem_map_t;

#define get_page(p)		atomic_inc(&(p)->count)
#define put_page(p)		__free_page(p)
#define put_page_testzero(p) 	atomic_dec_and_test(&(p)->count)
#define page_count(p)		atomic_read(&(p)->count)
#define set_page_count(p,v) 	atomic_set(&(p)->count, v)

/* Page flag bit values */
#define PG_locked		 0
#define PG_error		 1
#define PG_referenced		 2
#define PG_uptodate		 3
#define PG_dirty		 4
#define PG_decr_after		 5
#define PG_active		 6
#define PG_inactive_dirty	 7
#define PG_slab			 8
#define PG_swap_cache		 9
#define PG_skip			10
#define PG_inactive_clean	11
#define PG_highmem		12
				/* bits 21-29 unused */
#define PG_arch_1		30
#define PG_reserved		31

/* Make it prettier to test the above... */
#define Page_Uptodate(page)	test_bit(PG_uptodate, &(page)->flags)
#define SetPageUptodate(page)	set_bit(PG_uptodate, &(page)->flags)
#define ClearPageUptodate(page)	clear_bit(PG_uptodate, &(page)->flags)
#define PageDirty(page)		test_bit(PG_dirty, &(page)->flags)
#define SetPageDirty(page)	set_bit(PG_dirty, &(page)->flags)
#define ClearPageDirty(page)	clear_bit(PG_dirty, &(page)->flags)
#define PageLocked(page)	test_bit(PG_locked, &(page)->flags)
#define LockPage(page)		set_bit(PG_locked, &(page)->flags)
#define TryLockPage(page)	test_and_set_bit(PG_locked, &(page)->flags)

extern void __set_page_dirty(struct page *);

static inline void set_page_dirty(struct page * page)
{
	if (!test_and_set_bit(PG_dirty, &page->flags))
		__set_page_dirty(page);
}

/*
 * The first mb is necessary to safely close the critical section opened by the
 * TryLockPage(), the second mb is necessary to enforce ordering between
 * the clear_bit and the read of the waitqueue (to avoid SMP races with a
 * parallel wait_on_page).
 */
#define UnlockPage(page)	do { \
					smp_mb__before_clear_bit(); \
					if (!test_and_clear_bit(PG_locked, &(page)->flags)) BUG(); \
					smp_mb__after_clear_bit(); \
					if (waitqueue_active(&page->wait)) \
						wake_up(&page->wait); \
				} while (0)
#define PageError(page)		test_bit(PG_error, &(page)->flags)
#define SetPageError(page)	set_bit(PG_error, &(page)->flags)
#define ClearPageError(page)	clear_bit(PG_error, &(page)->flags)
#define PageReferenced(page)	test_bit(PG_referenced, &(page)->flags)
#define SetPageReferenced(page)	set_bit(PG_referenced, &(page)->flags)
#define ClearPageReferenced(page)	clear_bit(PG_referenced, &(page)->flags)
#define PageTestandClearReferenced(page)	test_and_clear_bit(PG_referenced, &(page)->flags)
#define PageDecrAfter(page)	test_bit(PG_decr_after, &(page)->flags)
#define SetPageDecrAfter(page)	set_bit(PG_decr_after, &(page)->flags)
#define PageTestandClearDecrAfter(page)	test_and_clear_bit(PG_decr_after, &(page)->flags)
#define PageSlab(page)		test_bit(PG_slab, &(page)->flags)
#define PageSwapCache(page)	test_bit(PG_swap_cache, &(page)->flags)
#define PageReserved(page)	test_bit(PG_reserved, &(page)->flags)

#define PageSetSlab(page)	set_bit(PG_slab, &(page)->flags)
#define PageSetSwapCache(page)	set_bit(PG_swap_cache, &(page)->flags)

#define PageTestandSetSwapCache(page)	test_and_set_bit(PG_swap_cache, &(page)->flags)

#define PageClearSlab(page)		clear_bit(PG_slab, &(page)->flags)
#define PageClearSwapCache(page)	clear_bit(PG_swap_cache, &(page)->flags)

#define PageTestandClearSwapCache(page)	test_and_clear_bit(PG_swap_cache, &(page)->flags)

#define PageActive(page)	test_bit(PG_active, &(page)->flags)
#define SetPageActive(page)	set_bit(PG_active, &(page)->flags)
#define ClearPageActive(page)	clear_bit(PG_active, &(page)->flags)

#define PageInactiveDirty(page)	test_bit(PG_inactive_dirty, &(page)->flags)
#define SetPageInactiveDirty(page)	set_bit(PG_inactive_dirty, &(page)->flags)
#define ClearPageInactiveDirty(page)	clear_bit(PG_inactive_dirty, &(page)->flags)

#define PageInactiveClean(page)	test_bit(PG_inactive_clean, &(page)->flags)
#define SetPageInactiveClean(page)	set_bit(PG_inactive_clean, &(page)->flags)
#define ClearPageInactiveClean(page)	clear_bit(PG_inactive_clean, &(page)->flags)

#ifdef CONFIG_HIGHMEM
#define PageHighMem(page)		test_bit(PG_highmem, &(page)->flags)
#else
#define PageHighMem(page)		0 /* needed to optimize away at compile time */
#endif

#define SetPageReserved(page)		set_bit(PG_reserved, &(page)->flags)
#define ClearPageReserved(page)		clear_bit(PG_reserved, &(page)->flags)

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


/*
 * Various page->flags bits:
 *
 * PG_reserved is set for a page which must never be accessed (which
 * may not even be present).
 *
 * PG_DMA has been removed, page->zone now tells exactly wether the
 * page is suited to do DMAing into.
 *