mm.h

嵌入式ARM的一些源代码

#ifndef _LINUX_MM_H
#define _LINUX_MM_H

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

#ifdef __KERNEL__

#include <linux/string.h>

extern unsigned long high_memory;

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

#define VERIFY_READ 0
#define VERIFY_WRITE 1

#ifdef DEBUG_VERIFY_AREA
#undef verify_area
extern int verify_area(int, const void *, unsigned long);
extern int verify_area_flf(int, const void *, unsigned long, char*file, int line, char*function);
#define verify_area(a,b,c) verify_area_flf(a,b,c,__FILE__,__LINE__,__FUNCTION__)

#else /* !DEBUG_VERIFY_AREA */
extern int verify_area(int, const void *, unsigned long);
#endif /* !DEBUG_VERIFY_AREA */

#ifdef MAGIC_ROM_PTR
extern int is_in_rom(unsigned long);
#endif /* !MAGIC_ROM_PTR */

/*
 * 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).
 */

#ifndef NO_MM

/*
 * 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;
	pgprot_t vm_page_prot;
	unsigned short 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;
/* linked list of VM areas per task, sorted by address */
	struct vm_area_struct * vm_next;
/* for areas with inode, the circular list inode->i_mmap */
/* for shm areas, the circular list of attaches */
/* otherwise unused */
	struct vm_area_struct * vm_next_share;
	struct vm_area_struct * vm_prev_share;
/* more */
	struct vm_operations_struct * vm_ops;
	unsigned long vm_offset;
	struct inode * vm_inode;
	unsigned long vm_pte;			/* shared mem */
};

#else /* NO_MM */


/* This dummy vm_area_struct does not define a VM area, it is only
   used to convey data between do_mmap and a f_op's mmap function. */
   
struct vm_area_struct {
	unsigned long vm_start;
	unsigned long vm_end;
	unsigned short vm_flags;
	unsigned long vm_offset;
};

#endif /* NO_MM */

/*
 * vm_flags..
 */
#define VM_READ		0x0001	/* currently active flags */
#define VM_WRITE	0x0002
#define VM_EXEC		0x0004
#define VM_SHARED	0x0008

#define VM_MAYREAD	0x0010	/* limits for mprotect() etc */
#define VM_MAYWRITE	0x0020
#define VM_MAYEXEC	0x0040
#define VM_MAYSHARE	0x0080

#define VM_GROWSDOWN	0x0100	/* general info on the segment */
#define VM_GROWSUP	0x0200
#define VM_SHM		0x0400	/* shared memory area, don't swap out */
#define VM_DENYWRITE	0x0800	/* ETXTBSY on write attempts.. */

#define VM_EXECUTABLE	0x1000
#define VM_LOCKED	0x2000

#define VM_STACK_FLAGS	0x0177

#ifndef NO_MM

/*
 * 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);
	void (*unmap)(struct vm_area_struct *area, unsigned long, size_t);
	void (*protect)(struct vm_area_struct *area, unsigned long, size_t, unsigned int newprot);
	int (*sync)(struct vm_area_struct *area, unsigned long, size_t, unsigned int flags);
	void (*advise)(struct vm_area_struct *area, unsigned long, size_t, unsigned int advise);
	unsigned long (*nopage)(struct vm_area_struct * area, unsigned long address, int write_access);
	unsigned long (*wppage)(struct vm_area_struct * area, unsigned long address,
		unsigned long page);
	int (*swapout)(struct vm_area_struct *,  unsigned long, pte_t *);
	pte_t (*swapin)(struct vm_area_struct *, unsigned long, unsigned long);
};

#endif /* !NO_MM */

/*
 * 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 {
	/* these must be first (free area handling) */
	struct page *next;
	struct page *prev;
	struct inode *inode;
	unsigned long offset;
	struct page *next_hash;
	atomic_t count;
	unsigned flags;	/* atomic flags, some possibly updated asynchronously */
	unsigned dirty:16,
		 age:8;
	struct wait_queue *wait;
	struct page *prev_hash;
	struct buffer_head * buffers;
	unsigned long swap_unlock_entry;
	unsigned long map_nr;	/* page->map_nr == page - mem_map */
} mem_map_t;

/* Page flag bit values */
#define PG_locked		 0
#define PG_error		 1
#define PG_referenced		 2
#define PG_uptodate		 3
#define PG_free_after		 4
#define PG_decr_after		 5
#define PG_swap_unlock_after	 6
#define PG_DMA			 7
#define PG_reserved		31

/* Make it prettier to test the above... */
#define PageLocked(page)	(test_bit(PG_locked, &(page)->flags))
#define PageError(page)		(test_bit(PG_error, &(page)->flags))
#define PageReferenced(page)	(test_bit(PG_referenced, &(page)->flags))
#define PageDirty(page)		(test_bit(PG_dirty, &(page)->flags))
#define PageUptodate(page)	(test_bit(PG_uptodate, &(page)->flags))
#define PageFreeAfter(page)	(test_bit(PG_free_after, &(page)->flags))
#define PageDecrAfter(page)	(test_bit(PG_decr_after, &(page)->flags))
#define PageSwapUnlockAfter(page) (test_bit(PG_swap_unlock_after, &(page)->flags))
#define PageDMA(page)		(test_bit(PG_DMA, &(page)->flags))
#define PageReserved(page)	(test_bit(PG_reserved, &(page)->flags))

/*
 * page->reserved denotes a page which must never be accessed (which
 * may not even be present).
 *
 * page->dma is set for those pages which lie in the range of
 * physical addresses capable of carrying DMA transfers.
 *
 * 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 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->inode is the inode, and page->offset is the file offset
 * of the page (not necessarily a multiple of PAGE_SIZE).
 *
 * A page may have buffers allocated to it. In this case,
 * page->buffers is a circular list of these buffer heads. Else,
 * page->buffers == NULL.
 *
 * For pages belonging to inodes, the page->count is the number of
 * attaches, plus 1 if buffers are allocated to the page.
 *
 * All pages belonging to an inode make up a doubly linked list
 * inode->i_pages, using the fields page->next and page->prev. (These
 * fields are also used for freelist management when page->count==0.)
 * There is also a hash table mapping (inode,offset) to the page
 * in memory if present. The lists for this hash table use the fields
 * page->next_hash and page->prev_hash.
 *
 * All process pages can do I/O:
 * - inode pages may need to be read from disk,