xref: /dragonfly/sys/vm/vm_mmap.c (revision e1acdbad)

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1991, 1993
 *	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 $Hdr: vm_mmap.c 1.6 91/10/21$
 *
 *	@(#)vm_mmap.c	8.4 (Berkeley) 1/12/94
 * $FreeBSD: src/sys/vm/vm_mmap.c,v 1.108.2.6 2002/07/02 20:06:19 dillon Exp $
 * $DragonFly: src/sys/vm/vm_mmap.c,v 1.21 2004/10/12 19:29:34 dillon Exp $
 */

/*
 * Mapped file (mmap) interface to VM
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/filedesc.h>
#include <sys/kern_syscall.h>
#include <sys/proc.h>
#include <sys/resource.h>
#include <sys/resourcevar.h>
#include <sys/vnode.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/mman.h>
#include <sys/conf.h>
#include <sys/stat.h>
#include <sys/vmmeter.h>
#include <sys/sysctl.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <sys/lock.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vm_pageout.h>
#include <vm/vm_extern.h>
#include <vm/vm_page.h>
#include <vm/vm_kern.h>

#include <sys/file2.h>
#include <sys/thread2.h>

static int max_proc_mmap;
SYSCTL_INT(_vm, OID_AUTO, max_proc_mmap, CTLFLAG_RW, &max_proc_mmap, 0, "");

/*
 * Set the maximum number of vm_map_entry structures per process.  Roughly
 * speaking vm_map_entry structures are tiny, so allowing them to eat 1/100
 * of our KVM malloc space still results in generous limits.  We want a
 * default that is good enough to prevent the kernel running out of resources
 * if attacked from compromised user account but generous enough such that
 * multi-threaded processes are not unduly inconvenienced.
 */

static void vmmapentry_rsrc_init (void *);
SYSINIT(vmmersrc, SI_SUB_KVM_RSRC, SI_ORDER_FIRST, vmmapentry_rsrc_init, NULL)

static void
vmmapentry_rsrc_init(void *dummy)
{
    max_proc_mmap = (VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) /
			sizeof(struct vm_map_entry);
    max_proc_mmap /= 100;
}

/* ARGSUSED */
int
sbrk(struct sbrk_args *uap)
{
	/* Not yet implemented */
	return (EOPNOTSUPP);
}

/*
 * sstk_args(int incr)
 */
/* ARGSUSED */
int
sstk(struct sstk_args *uap)
{
	/* Not yet implemented */
	return (EOPNOTSUPP);
}

/*
 * mmap_args(void *addr, size_t len, int prot, int flags, int fd,
 *		long pad, off_t pos)
 *
 * Memory Map (mmap) system call.  Note that the file offset
 * and address are allowed to be NOT page aligned, though if
 * the MAP_FIXED flag it set, both must have the same remainder
 * modulo the PAGE_SIZE (POSIX 1003.1b).  If the address is not
 * page-aligned, the actual mapping starts at trunc_page(addr)
 * and the return value is adjusted up by the page offset.
 *
 * Generally speaking, only character devices which are themselves
 * memory-based, such as a video framebuffer, can be mmap'd.  Otherwise
 * there would be no cache coherency between a descriptor and a VM mapping
 * both to the same character device.
 *
 * Block devices can be mmap'd no matter what they represent.  Cache coherency
 * is maintained as long as you do not write directly to the underlying
 * character device.
 */

int
kern_mmap(caddr_t uaddr, size_t ulen, int uprot, int uflags, int fd,
    off_t upos, void **res)
{
	struct thread *td = curthread;
 	struct proc *p = td->td_proc;
	struct filedesc *fdp = p->p_fd;
	struct file *fp = NULL;
	struct vnode *vp;
	vm_offset_t addr;
	vm_size_t size, pageoff;
	vm_prot_t prot, maxprot;
	void *handle;
	int flags, error;
	int disablexworkaround;
	off_t pos;
	struct vmspace *vms = p->p_vmspace;
	vm_object_t obj;

	KKASSERT(p);

	addr = (vm_offset_t) uaddr;
	size = ulen;
	prot = uprot & VM_PROT_ALL;
	flags = uflags;
	pos = upos;

	/* make sure mapping fits into numeric range etc */
	if ((ssize_t) ulen < 0 ||
	    ((flags & MAP_ANON) && fd != -1))
		return (EINVAL);

	if (flags & MAP_STACK) {
		if ((fd != -1) ||
		    ((prot & (PROT_READ | PROT_WRITE)) != (PROT_READ | PROT_WRITE)))
			return (EINVAL);
		flags |= MAP_ANON;
		pos = 0;
	}

	/*
	 * Align the file position to a page boundary,
	 * and save its page offset component.
	 */
	pageoff = (pos & PAGE_MASK);
	pos -= pageoff;

	/* Adjust size for rounding (on both ends). */
	size += pageoff;			/* low end... */
	size = (vm_size_t) round_page(size);	/* hi end */

	/*
	 * Check for illegal addresses.  Watch out for address wrap... Note
	 * that VM_*_ADDRESS are not constants due to casts (argh).
	 */
	if (flags & MAP_FIXED) {
		/*
		 * The specified address must have the same remainder
		 * as the file offset taken modulo PAGE_SIZE, so it
		 * should be aligned after adjustment by pageoff.
		 */
		addr -= pageoff;
		if (addr & PAGE_MASK)
			return (EINVAL);
		/* Address range must be all in user VM space. */
		if (VM_MAXUSER_ADDRESS > 0 && addr + size > VM_MAXUSER_ADDRESS)
			return (EINVAL);
#ifndef i386
		if (VM_MIN_ADDRESS > 0 && addr < VM_MIN_ADDRESS)
			return (EINVAL);
#endif
		if (addr + size < addr)
			return (EINVAL);
	}
	/*
	 * XXX for non-fixed mappings where no hint is provided or
	 * the hint would fall in the potential heap space,
	 * place it after the end of the largest possible heap.
	 *
	 * There should really be a pmap call to determine a reasonable
	 * location.
	 */
	else if (addr == 0 ||
	    (addr >= round_page((vm_offset_t)vms->vm_taddr) &&
	     addr < round_page((vm_offset_t)vms->vm_daddr + maxdsiz)))
		addr = round_page((vm_offset_t)vms->vm_daddr + maxdsiz);

	if (flags & MAP_ANON) {
		/*
		 * Mapping blank space is trivial.
		 */
		handle = NULL;
		maxprot = VM_PROT_ALL;
		pos = 0;
	} else {
		/*
		 * Mapping file, get fp for validation. Obtain vnode and make
		 * sure it is of appropriate type.
		 */
		if (((unsigned) fd) >= fdp->fd_nfiles ||
		    (fp = fdp->fd_ofiles[fd]) == NULL)
			return (EBADF);
		if (fp->f_type != DTYPE_VNODE)
			return (EINVAL);
		/*
		 * POSIX shared-memory objects are defined to have
		 * kernel persistence, and are not defined to support
		 * read(2)/write(2) -- or even open(2).  Thus, we can
		 * use MAP_ASYNC to trade on-disk coherence for speed.
		 * The shm_open(3) library routine turns on the FPOSIXSHM
		 * flag to request this behavior.
		 */
		if (fp->f_flag & FPOSIXSHM)
			flags |= MAP_NOSYNC;
		vp = (struct vnode *) fp->f_data;
		if (vp->v_type != VREG && vp->v_type != VCHR)
			return (EINVAL);
		if (vp->v_type == VREG) {
			/*
			 * Get the proper underlying object
			 */
			if (VOP_GETVOBJECT(vp, &obj) != 0)
				return (EINVAL);
			vp = (struct vnode*)obj->handle;
		}

		/*
		 * don't let the descriptor disappear on us if we block
		 */
		fhold(fp);

		/*
		 * XXX hack to handle use of /dev/zero to map anon memory (ala
		 * SunOS).
		 */
		if (vp->v_type == VCHR && iszerodev(vp->v_rdev)) {
			handle = NULL;
			maxprot = VM_PROT_ALL;
			flags |= MAP_ANON;
			pos = 0;
		} else {
			/*
			 * cdevs does not provide private mappings of any kind.
			 */
			/*
			 * However, for XIG X server to continue to work,
			 * we should allow the superuser to do it anyway.
			 * We only allow it at securelevel < 1.
			 * (Because the XIG X server writes directly to video
			 * memory via /dev/mem, it should never work at any
			 * other securelevel.
			 * XXX this will have to go
			 */
			if (securelevel >= 1)
				disablexworkaround = 1;
			else
				disablexworkaround = suser(td);
			if (vp->v_type == VCHR && disablexworkaround &&
			    (flags & (MAP_PRIVATE|MAP_COPY))) {
				error = EINVAL;
				goto done;
			}
			/*
			 * Ensure that file and memory protections are
			 * compatible.  Note that we only worry about
			 * writability if mapping is shared; in this case,
			 * current and max prot are dictated by the open file.
			 * XXX use the vnode instead?  Problem is: what
			 * credentials do we use for determination? What if
			 * proc does a setuid?
			 */
			maxprot = VM_PROT_EXECUTE;	/* ??? */
			if (fp->f_flag & FREAD) {
				maxprot |= VM_PROT_READ;
			} else if (prot & PROT_READ) {
				error = EACCES;
				goto done;
			}
			/*
			 * If we are sharing potential changes (either via
			 * MAP_SHARED or via the implicit sharing of character
			 * device mappings), and we are trying to get write
			 * permission although we opened it without asking
			 * for it, bail out.  Check for superuser, only if
			 * we're at securelevel < 1, to allow the XIG X server
			 * to continue to work.
			 */

			if ((flags & MAP_SHARED) != 0 ||
			    (vp->v_type == VCHR && disablexworkaround)) {
				if ((fp->f_flag & FWRITE) != 0) {
					struct vattr va;
					if ((error = VOP_GETATTR(vp, &va, td))) {
						goto done;
					}
					if ((va.va_flags &
					    (IMMUTABLE|APPEND)) == 0) {
						maxprot |= VM_PROT_WRITE;
					} else if (prot & PROT_WRITE) {
						error = EPERM;
						goto done;
					}
				} else if ((prot & PROT_WRITE) != 0) {
					error = EACCES;
					goto done;
				}
			} else {
				maxprot |= VM_PROT_WRITE;
			}
			handle = (void *)vp;
		}
	}

	/*
	 * Do not allow more then a certain number of vm_map_entry structures
	 * per process.  Scale with the number of rforks sharing the map
	 * to make the limit reasonable for threads.
	 */
	if (max_proc_mmap &&
	    vms->vm_map.nentries >= max_proc_mmap * vms->vm_refcnt) {
		error = ENOMEM;
		goto done;
	}

	error = vm_mmap(&vms->vm_map, &addr, size, prot, maxprot,
	    flags, handle, pos);
	if (error == 0)
		*res = (void *)(addr + pageoff);
done:
	if (fp)
		fdrop(fp, td);
	return (error);
}

int
mmap(struct mmap_args *uap)
{
	int error;

	error = kern_mmap(uap->addr, uap->len, uap->prot, uap->flags,
	    uap->fd, uap->pos, &uap->sysmsg_resultp);

	return (error);
}

/*
 * msync_args(void *addr, int len, int flags)
 */
int
msync(struct msync_args *uap)
{
	struct proc *p = curproc;
	vm_offset_t addr;
	vm_size_t size, pageoff;
	int flags;
	vm_map_t map;
	int rv;

	addr = (vm_offset_t) uap->addr;
	size = uap->len;
	flags = uap->flags;

	pageoff = (addr & PAGE_MASK);
	addr -= pageoff;
	size += pageoff;
	size = (vm_size_t) round_page(size);
	if (addr + size < addr)
		return(EINVAL);

	if ((flags & (MS_ASYNC|MS_INVALIDATE)) == (MS_ASYNC|MS_INVALIDATE))
		return (EINVAL);

	map = &p->p_vmspace->vm_map;

	/*
	 * XXX Gak!  If size is zero we are supposed to sync "all modified
	 * pages with the region containing addr".  Unfortunately, we don't
	 * really keep track of individual mmaps so we approximate by flushing
	 * the range of the map entry containing addr. This can be incorrect
	 * if the region splits or is coalesced with a neighbor.
	 */
	if (size == 0) {
		vm_map_entry_t entry;

		vm_map_lock_read(map);
		rv = vm_map_lookup_entry(map, addr, &entry);
		vm_map_unlock_read(map);
		if (rv == FALSE)
			return (EINVAL);
		addr = entry->start;
		size = entry->end - entry->start;
	}

	/*
	 * Clean the pages and interpret the return value.
	 */
	rv = vm_map_clean(map, addr, addr + size, (flags & MS_ASYNC) == 0,
	    (flags & MS_INVALIDATE) != 0);

	switch (rv) {
	case KERN_SUCCESS:
		break;
	case KERN_INVALID_ADDRESS:
		return (EINVAL);	/* Sun returns ENOMEM? */
	case KERN_FAILURE:
		return (EIO);
	default:
		return (EINVAL);
	}

	return (0);
}

/*
 * munmap_args(void *addr, size_t len)
 */
int
munmap(struct munmap_args *uap)
{
	struct proc *p = curproc;
	vm_offset_t addr;
	vm_size_t size, pageoff;
	vm_map_t map;

	addr = (vm_offset_t) uap->addr;
	size = uap->len;

	pageoff = (addr & PAGE_MASK);
	addr -= pageoff;
	size += pageoff;
	size = (vm_size_t) round_page(size);
	if (addr + size < addr)
		return(EINVAL);

	if (size == 0)
		return (0);

	/*
	 * Check for illegal addresses.  Watch out for address wrap... Note
	 * that VM_*_ADDRESS are not constants due to casts (argh).
	 */
	if (VM_MAXUSER_ADDRESS > 0 && addr + size > VM_MAXUSER_ADDRESS)
		return (EINVAL);
#ifndef i386
	if (VM_MIN_ADDRESS > 0 && addr < VM_MIN_ADDRESS)
		return (EINVAL);
#endif
	map = &p->p_vmspace->vm_map;
	/*
	 * Make sure entire range is allocated.
	 */
	if (!vm_map_check_protection(map, addr, addr + size, VM_PROT_NONE))
		return (EINVAL);
	/* returns nothing but KERN_SUCCESS anyway */
	(void) vm_map_remove(map, addr, addr + size);
	return (0);
}

#if 0
void
munmapfd(p, fd)
	struct proc *p;
	int fd;
{
	/*
	 * XXX should unmap any regions mapped to this file
	 */
	p->p_fd->fd_ofileflags[fd] &= ~UF_MAPPED;
}
#endif

/*
 * mprotect_args(const void *addr, size_t len, int prot)
 */
int
mprotect(struct mprotect_args *uap)
{
	struct proc *p = curproc;
	vm_offset_t addr;
	vm_size_t size, pageoff;
	vm_prot_t prot;

	addr = (vm_offset_t) uap->addr;
	size = uap->len;
	prot = uap->prot & VM_PROT_ALL;
#if defined(VM_PROT_READ_IS_EXEC)
	if (prot & VM_PROT_READ)
		prot |= VM_PROT_EXECUTE;
#endif

	pageoff = (addr & PAGE_MASK);
	addr -= pageoff;
	size += pageoff;
	size = (vm_size_t) round_page(size);
	if (addr + size < addr)
		return(EINVAL);

	switch (vm_map_protect(&p->p_vmspace->vm_map, addr, addr + size, prot,
		FALSE)) {
	case KERN_SUCCESS:
		return (0);
	case KERN_PROTECTION_FAILURE:
		return (EACCES);
	}
	return (EINVAL);
}

/*
 * minherit_args(void *addr, size_t len, int inherit)
 */
int
minherit(struct minherit_args *uap)
{
	struct proc *p = curproc;
	vm_offset_t addr;
	vm_size_t size, pageoff;
	vm_inherit_t inherit;

	addr = (vm_offset_t)uap->addr;
	size = uap->len;
	inherit = uap->inherit;

	pageoff = (addr & PAGE_MASK);
	addr -= pageoff;
	size += pageoff;
	size = (vm_size_t) round_page(size);
	if (addr + size < addr)
		return(EINVAL);

	switch (vm_map_inherit(&p->p_vmspace->vm_map, addr, addr+size,
	    inherit)) {
	case KERN_SUCCESS:
		return (0);
	case KERN_PROTECTION_FAILURE:
		return (EACCES);
	}
	return (EINVAL);
}

/*
 * madvise_args(void *addr, size_t len, int behav)
 */
/* ARGSUSED */
int
madvise(struct madvise_args *uap)
{
	struct proc *p = curproc;
	vm_offset_t start, end;

	/*
	 * Check for illegal behavior
	 */
	if (uap->behav < 0 || uap->behav > MADV_CORE)
		return (EINVAL);
	/*
	 * Check for illegal addresses.  Watch out for address wrap... Note
	 * that VM_*_ADDRESS are not constants due to casts (argh).
	 */
	if (VM_MAXUSER_ADDRESS > 0 &&
		((vm_offset_t) uap->addr + uap->len) > VM_MAXUSER_ADDRESS)
		return (EINVAL);
#ifndef i386
	if (VM_MIN_ADDRESS > 0 && uap->addr < VM_MIN_ADDRESS)
		return (EINVAL);
#endif
	if (((vm_offset_t) uap->addr + uap->len) < (vm_offset_t) uap->addr)
		return (EINVAL);

	/*
	 * Since this routine is only advisory, we default to conservative
	 * behavior.
	 */
	start = trunc_page((vm_offset_t) uap->addr);
	end = round_page((vm_offset_t) uap->addr + uap->len);

	if (vm_map_madvise(&p->p_vmspace->vm_map, start, end, uap->behav))
		return (EINVAL);
	return (0);
}

/*
 * mincore_args(const void *addr, size_t len, char *vec)
 */
/* ARGSUSED */
int
mincore(struct mincore_args *uap)
{
	struct proc *p = curproc;
	vm_offset_t addr, first_addr;
	vm_offset_t end, cend;
	pmap_t pmap;
	vm_map_t map;
	char *vec;
	int error;
	int vecindex, lastvecindex;
	vm_map_entry_t current;
	vm_map_entry_t entry;
	int mincoreinfo;
	unsigned int timestamp;

	/*
	 * Make sure that the addresses presented are valid for user
	 * mode.
	 */
	first_addr = addr = trunc_page((vm_offset_t) uap->addr);
	end = addr + (vm_size_t)round_page(uap->len);
	if (VM_MAXUSER_ADDRESS > 0 && end > VM_MAXUSER_ADDRESS)
		return (EINVAL);
	if (end < addr)
		return (EINVAL);

	/*
	 * Address of byte vector
	 */
	vec = uap->vec;

	map = &p->p_vmspace->vm_map;
	pmap = vmspace_pmap(p->p_vmspace);

	vm_map_lock_read(map);
RestartScan:
	timestamp = map->timestamp;

	if (!vm_map_lookup_entry(map, addr, &entry))
		entry = entry->next;

	/*
	 * Do this on a map entry basis so that if the pages are not
	 * in the current processes address space, we can easily look
	 * up the pages elsewhere.
	 */
	lastvecindex = -1;
	for(current = entry;
		(current != &map->header) && (current->start < end);
		current = current->next) {

		/*
		 * ignore submaps (for now) or null objects
		 */
		if ((current->eflags & MAP_ENTRY_IS_SUB_MAP) ||
			current->object.vm_object == NULL)
			continue;

		/*
		 * limit this scan to the current map entry and the
		 * limits for the mincore call
		 */
		if (addr < current->start)
			addr = current->start;
		cend = current->end;
		if (cend > end)
			cend = end;

		/*
		 * scan this entry one page at a time
		 */
		while (addr < cend) {
			/*
			 * Check pmap first, it is likely faster, also
			 * it can provide info as to whether we are the
			 * one referencing or modifying the page.
			 */
			mincoreinfo = pmap_mincore(pmap, addr);
			if (!mincoreinfo) {
				vm_pindex_t pindex;
				vm_ooffset_t offset;
				vm_page_t m;

				/*
				 * calculate the page index into the object
				 */
				offset = current->offset + (addr - current->start);
				pindex = OFF_TO_IDX(offset);

				/*
				 * if the page is resident, then gather
				 * information about it.  spl protection is
				 * required to maintain the object
				 * association.  And XXX what if the page is
				 * busy?  What's the deal with that?
				 */
				crit_enter();
				m = vm_page_lookup(current->object.vm_object,
						    pindex);
				if (m && m->valid) {
					mincoreinfo = MINCORE_INCORE;
					if (m->dirty ||
						pmap_is_modified(m))
						mincoreinfo |= MINCORE_MODIFIED_OTHER;
					if ((m->flags & PG_REFERENCED) ||
						pmap_ts_referenced(m)) {
						vm_page_flag_set(m, PG_REFERENCED);
						mincoreinfo |= MINCORE_REFERENCED_OTHER;
					}
				}
				crit_exit();
			}

			/*
			 * subyte may page fault.  In case it needs to modify
			 * the map, we release the lock.
			 */
			vm_map_unlock_read(map);

			/*
			 * calculate index into user supplied byte vector
			 */
			vecindex = OFF_TO_IDX(addr - first_addr);

			/*
			 * If we have skipped map entries, we need to make sure that
			 * the byte vector is zeroed for those skipped entries.
			 */
			while((lastvecindex + 1) < vecindex) {
				error = subyte( vec + lastvecindex, 0);
				if (error) {
					return (EFAULT);
				}
				++lastvecindex;
			}

			/*
			 * Pass the page information to the user
			 */
			error = subyte( vec + vecindex, mincoreinfo);
			if (error) {
				return (EFAULT);
			}

			/*
			 * If the map has changed, due to the subyte, the previous
			 * output may be invalid.
			 */
			vm_map_lock_read(map);
			if (timestamp != map->timestamp)
				goto RestartScan;

			lastvecindex = vecindex;
			addr += PAGE_SIZE;
		}
	}

	/*
	 * subyte may page fault.  In case it needs to modify
	 * the map, we release the lock.
	 */
	vm_map_unlock_read(map);

	/*
	 * Zero the last entries in the byte vector.
	 */
	vecindex = OFF_TO_IDX(end - first_addr);
	while((lastvecindex + 1) < vecindex) {
		error = subyte( vec + lastvecindex, 0);
		if (error) {
			return (EFAULT);
		}
		++lastvecindex;
	}

	/*
	 * If the map has changed, due to the subyte, the previous
	 * output may be invalid.
	 */
	vm_map_lock_read(map);
	if (timestamp != map->timestamp)
		goto RestartScan;
	vm_map_unlock_read(map);

	return (0);
}

/*
 * mlock_args(const void *addr, size_t len)
 */
int
mlock(struct mlock_args *uap)
{
	vm_offset_t addr;
	vm_size_t size, pageoff;
	int error;
	struct proc *p = curproc;

	addr = (vm_offset_t) uap->addr;
	size = uap->len;

	pageoff = (addr & PAGE_MASK);
	addr -= pageoff;
	size += pageoff;
	size = (vm_size_t) round_page(size);

	/* disable wrap around */
	if (addr + size < addr)
		return (EINVAL);

	if (atop(size) + vmstats.v_wire_count > vm_page_max_wired)
		return (EAGAIN);

#ifdef pmap_wired_count
	if (size + ptoa(pmap_wired_count(vm_map_pmap(&p->p_vmspace->vm_map))) >
	    p->p_rlimit[RLIMIT_MEMLOCK].rlim_cur)
		return (ENOMEM);
#else
	error = suser_cred(p->p_ucred, 0);
	if (error)
		return (error);
#endif

	error = vm_map_unwire(&p->p_vmspace->vm_map, addr, addr + size, FALSE);
	return (error == KERN_SUCCESS ? 0 : ENOMEM);
}

/*
 * mlockall_args(int how)
 */
int
mlockall(struct mlockall_args *uap)
{
	return 0;
}

/*
 * munlockall_args(void)
 */
int
munlockall(struct munlockall_args *uap)
{
	return 0;
}

/*
 * munlock_args(const void *addr, size_t len)
 */
int
munlock(struct munlock_args *uap)
{
	struct thread *td = curthread;
	struct proc *p = td->td_proc;
	vm_offset_t addr;
	vm_size_t size, pageoff;
	int error;

	addr = (vm_offset_t) uap->addr;
	size = uap->len;

	pageoff = (addr & PAGE_MASK);
	addr -= pageoff;
	size += pageoff;
	size = (vm_size_t) round_page(size);

	/* disable wrap around */
	if (addr + size < addr)
		return (EINVAL);

#ifndef pmap_wired_count
	error = suser(td);
	if (error)
		return (error);
#endif

	error = vm_map_unwire(&p->p_vmspace->vm_map, addr, addr + size, TRUE);
	return (error == KERN_SUCCESS ? 0 : ENOMEM);
}

/*
 * Internal version of mmap.
 * Currently used by mmap, exec, and sys5 shared memory.
 * Handle is either a vnode pointer or NULL for MAP_ANON.
 */
int
vm_mmap(vm_map_t map, vm_offset_t *addr, vm_size_t size, vm_prot_t prot,
	vm_prot_t maxprot, int flags,
	void *handle,
	vm_ooffset_t foff)
{
	boolean_t fitit;
	vm_object_t object;
	struct vnode *vp = NULL;
	objtype_t type;
	int rv = KERN_SUCCESS;
	vm_ooffset_t objsize;
	int docow;
	struct thread *td = curthread;	/* XXX */
	struct proc *p = td->td_proc;

	KKASSERT(p);

	if (size == 0)
		return (0);

	objsize = size = round_page(size);

	if (p->p_vmspace->vm_map.size + size >
	    p->p_rlimit[RLIMIT_VMEM].rlim_cur) {
		return(ENOMEM);
	}

	/*
	 * We currently can only deal with page aligned file offsets.
	 * The check is here rather than in the syscall because the
	 * kernel calls this function internally for other mmaping
	 * operations (such as in exec) and non-aligned offsets will
	 * cause pmap inconsistencies...so we want to be sure to
	 * disallow this in all cases.
	 */
	if (foff & PAGE_MASK)
		return (EINVAL);

	if ((flags & MAP_FIXED) == 0) {
		fitit = TRUE;
		*addr = round_page(*addr);
	} else {
		if (*addr != trunc_page(*addr))
			return (EINVAL);
		fitit = FALSE;
		(void) vm_map_remove(map, *addr, *addr + size);
	}

	/*
	 * Lookup/allocate object.
	 */
	if (flags & MAP_ANON) {
		type = OBJT_DEFAULT;
		/*
		 * Unnamed anonymous regions always start at 0.
		 */
		if (handle == 0)
			foff = 0;
	} else {
		vp = (struct vnode *) handle;
		if (vp->v_type == VCHR) {
			type = OBJT_DEVICE;
			handle = (void *)(intptr_t)vp->v_rdev;
		} else {
			struct vattr vat;
			int error;

			error = VOP_GETATTR(vp, &vat, td);
			if (error)
				return (error);
			objsize = round_page(vat.va_size);
			type = OBJT_VNODE;
			/*
			 * if it is a regular file without any references
			 * we do not need to sync it.
			 */
			if (vp->v_type == VREG && vat.va_nlink == 0) {
				flags |= MAP_NOSYNC;
			}
		}
	}

	if (handle == NULL) {
		object = NULL;
		docow = 0;
	} else {
		object = vm_pager_allocate(type,
			handle, objsize, prot, foff);
		if (object == NULL)
			return (type == OBJT_DEVICE ? EINVAL : ENOMEM);
		docow = MAP_PREFAULT_PARTIAL;
	}

	/*
	 * Force device mappings to be shared.
	 */
	if (type == OBJT_DEVICE || type == OBJT_PHYS) {
		flags &= ~(MAP_PRIVATE|MAP_COPY);
		flags |= MAP_SHARED;
	}

	if ((flags & (MAP_ANON|MAP_SHARED)) == 0)
		docow |= MAP_COPY_ON_WRITE;
	if (flags & MAP_NOSYNC)
		docow |= MAP_DISABLE_SYNCER;
	if (flags & MAP_NOCORE)
		docow |= MAP_DISABLE_COREDUMP;

#if defined(VM_PROT_READ_IS_EXEC)
	if (prot & VM_PROT_READ)
		prot |= VM_PROT_EXECUTE;

	if (maxprot & VM_PROT_READ)
		maxprot |= VM_PROT_EXECUTE;
#endif

	if (fitit) {
		*addr = pmap_addr_hint(object, *addr, size);
	}

	if (flags & MAP_STACK)
		rv = vm_map_stack (map, *addr, size, prot,
				   maxprot, docow);
	else
		rv = vm_map_find(map, object, foff, addr, size, fitit,
				 prot, maxprot, docow);

	if (rv != KERN_SUCCESS) {
		/*
		 * Lose the object reference. Will destroy the
		 * object if it's an unnamed anonymous mapping
		 * or named anonymous without other references.
		 */
		vm_object_deallocate(object);
		goto out;
	}

	/*
	 * Shared memory is also shared with children.
	 */
	if (flags & (MAP_SHARED|MAP_INHERIT)) {
		rv = vm_map_inherit(map, *addr, *addr + size, VM_INHERIT_SHARE);
		if (rv != KERN_SUCCESS) {
			(void) vm_map_remove(map, *addr, *addr + size);
			goto out;
		}
	}
out:
	switch (rv) {
	case KERN_SUCCESS:
		return (0);
	case KERN_INVALID_ADDRESS:
	case KERN_NO_SPACE:
		return (ENOMEM);
	case KERN_PROTECTION_FAILURE:
		return (EACCES);
	default:
		return (EINVAL);
	}
}