Source to sys/mapmem.h


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/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * from: Utah $Hdr: mmap.h 1.4 89/08/14$
 *
 *	@(#)mapmem.h	7.2 (Berkeley) 6/6/90
 */

/*
 * Mapped memory descriptors.
 *
 * A process has one of these for every "mapped" memory region.
 * Mapped memory is characterized by:
 *	- Corresponding physical memory is neither paged nor swapped.
 *	- User PTEs have both pg_v and pg_fod set.
 *	- Has no backing swap space unless mapped over existing data.
 *	- If mapped over existing data, original data is lost when
 *	  segment is unmapped. (i.e. pages are reinitialized to ZFOD)
 * Operations:
 *	(*mm_fork)(mp, ischild) struct mapmem *mp; int ischild;
 *		Called during fork in both parent and child.  Parent
 *		call can be used for maintaining reference counts and
 *		should NEVER destroy the region.  Child call should be
 *		used for unmapping regions not inherited across forks.
 *	(*mm_vfork)(mp, fup, tup) struct mapmem *mp; struct user *fup, *tup;
 *		Called twice during vfork (always in parent context)
 *		after exchanging resources (including u_mmap chains).
 *		`fup' is the donor and `tup' the recipient of the
 *		"parent" (full) context.  Needed for maintaining
 *		reference counts or if the underlying object contains
 *		references to owning process.  Routine should NEVER
 *		destroy the region.
 *	(*mm_exec)(mp) struct mapmem *mp;
 *		Called during exec before releasing old address space.
 *		Used for graceful cleanup of underlying object.  Resources
 *		will be freed regardless of what this routine does.
 *		Need to add a post-exec call to re-establish mappings
 *		in the new address space for regions inherited across execs.
 *	(*mm_exit)(mp) struct mapmem *mp;
 *		Called during exit just before releasing address space.
 *		Used for graceful cleanup of underlying object.  Resources
 *		will be freed regardless of what this routine does.
 * The default semantics for a region with routine addresses of zero are
 * that it is inherited across forks, stays with the "active" process during
 * vforks, and is destroyed by execs and exit.
 */

struct mapmem {
	struct	mapmem *mm_next;	/* next descriptor */
	int	mm_id;			/* identifier (e.g. fd, shmid) */
	caddr_t	mm_uva;			/* user VA at which region is mapped */
	int	mm_size;		/* size of mapped region */
	int	mm_prot;		/* attributes of region */
	struct mapmemops {		/* operations */
		int	(*mm_fork)();
		int	(*mm_vfork)();
		int	(*mm_exec)();
		int	(*mm_exit)();
	} *mm_ops;
};

#define MMNIL	((struct mapmem *)0)

/* attributes */
#define MM_RW		0x00	/* region is read-write */
#define	MM_RO		0x01	/* region is read-only */
#define MM_CI		0x02	/* caching is inhibited on region */
#define MM_NOCORE	0x04	/* cannot write region to core file;
				   e.g. mapped framebuffer hardware */

#ifdef KERNEL
#define MMALLOC(mp) \
	(mp) = (struct mapmem *)malloc((u_long)sizeof(struct mapmem), \
	    M_MAPMEM, M_WAITOK)

#define MMFREE(mp) \
	free((caddr_t)(mp), M_MAPMEM)
#endif