kernel - refactor vm_page busy

[dragonfly.git] / sys / vm / vm_mmap.c

/*
 * (MPSAFE)
 *
 * 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. 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 $
 */

/*
 * 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/priv.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_kern.h>

#include <sys/file2.h>
#include <sys/thread.h>
#include <sys/thread2.h>
#include <vm/vm_page2.h>

static int max_proc_mmap;
SYSCTL_INT(_vm, OID_AUTO, max_proc_mmap, CTLFLAG_RW, &max_proc_mmap, 0, "");
int vkernel_enable;
SYSCTL_INT(_vm, OID_AUTO, vkernel_enable, CTLFLAG_RW, &vkernel_enable, 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_BOOT1_POST, SI_ORDER_ANY, vmmapentry_rsrc_init, NULL);

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

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

/*
 * sstk_args(int incr)
 *
 * MPSAFE
 */
int
sys_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.
 *
 * No requirements
 */
int
kern_mmap(struct vmspace *vms, 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 file *fp = NULL;
        struct vnode *vp;
        vm_offset_t addr;
        vm_offset_t tmpaddr;
        vm_size_t size, pageoff;
        vm_prot_t prot, maxprot;
        void *handle;
        int flags, error;
        off_t pos;
        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.
         *
         * NOTE: We support the full unsigned range for size now.
         */
        if (((flags & MAP_ANON) && (fd != -1 || pos != 0)))
                return (EINVAL);

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

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

        /*
         * Virtual page tables cannot be used with MAP_STACK.  Apart from
         * it not making any sense, the aux union is used by both
         * types.
         *
         * Because the virtual page table is stored in the backing object
         * and might be updated by the kernel, the mapping must be R+W.
         */
        if (flags & MAP_VPAGETABLE) {
                if (vkernel_enable == 0)
                        return (EOPNOTSUPP);
                if (flags & MAP_STACK)
                        return (EINVAL);
                if ((prot & (PROT_READ|PROT_WRITE)) != (PROT_READ|PROT_WRITE))
                        return (EINVAL);
        }

        /*
         * 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 */
        if (size < ulen)                        /* wrap */
                return(EINVAL);

        /*
         * Check for illegal addresses.  Watch out for address wrap... Note
         * that VM_*_ADDRESS are not constants due to casts (argh).
         */
        if (flags & (MAP_FIXED | MAP_TRYFIXED)) {
                /*
                 * 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 and not wrap.
                 */
                tmpaddr = addr + size;
                if (tmpaddr < addr)
                        return (EINVAL);
                if (VM_MAX_USER_ADDRESS > 0 && tmpaddr > VM_MAX_USER_ADDRESS)
                        return (EINVAL);
                if (VM_MIN_USER_ADDRESS > 0 && addr < VM_MIN_USER_ADDRESS)
                        return (EINVAL);
        } else {
                /*
                 * Get a hint of where to map. It also provides mmap offset
                 * randomization if enabled.
                 */
                addr = vm_map_hint(p, addr, prot);
        }

        if (flags & MAP_ANON) {
                /*
                 * Mapping blank space is trivial.
                 */
                handle = NULL;
                maxprot = VM_PROT_ALL;
        } else {
                /*
                 * Mapping file, get fp for validation. Obtain vnode and make
                 * sure it is of appropriate type.
                 */
                fp = holdfp(p->p_fd, fd, -1);
                if (fp == NULL)
                        return (EBADF);
                if (fp->f_type != DTYPE_VNODE) {
                        error = EINVAL;
                        goto done;
                }
                /*
                 * 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;

                /*
                 * Validate the vnode for the operation.
                 */
                switch(vp->v_type) {
                case VREG:
                        /*
                         * Get the proper underlying object
                         */
                        if ((obj = vp->v_object) == NULL) {
                                error = EINVAL;
                                goto done;
                        }
                        KKASSERT((struct vnode *)obj->handle == vp);
                        break;
                case VCHR:
                        /*
                         * Make sure a device has not been revoked.  
                         * Mappability is handled by the device layer.
                         */
                        if (vp->v_rdev == NULL) {
                                error = EBADF;
                                goto done;
                        }
                        break;
                default:
                        /*
                         * Nothing else is mappable.
                         */
                        error = EINVAL;
                        goto done;
                }

                /*
                 * 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.
                         */
                        if (vp->v_type == VCHR &&
                            (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) {
                                if ((fp->f_flag & FWRITE) != 0) {
                                        struct vattr va;
                                        if ((error = VOP_GETATTR(vp, &va))) {
                                                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;
                }
        }

        lwkt_gettoken(&vms->vm_map.token);

        /*
         * 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 * vmspace_getrefs(vms)) {
                error = ENOMEM;
                lwkt_reltoken(&vms->vm_map.token);
                goto done;
        }

        error = vm_mmap(&vms->vm_map, &addr, size, prot, maxprot,
                        flags, handle, pos);
        if (error == 0)
                *res = (void *)(addr + pageoff);

        lwkt_reltoken(&vms->vm_map.token);
done:
        if (fp)
                fdrop(fp);

        return (error);
}

/*
 * mmap system call handler
 *
 * No requirements.
 */
int
sys_mmap(struct mmap_args *uap)
{
        int error;

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

        return (error);
}

/*
 * msync system call handler 
 *
 * msync_args(void *addr, size_t len, int flags)
 *
 * No requirements
 */
int
sys_msync(struct msync_args *uap)
{
        struct proc *p = curproc;
        vm_offset_t addr;
        vm_offset_t tmpaddr;
        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 (size < uap->len)            /* wrap */
                return(EINVAL);
        tmpaddr = addr + size;          /* workaround gcc4 opt */
        if (tmpaddr < addr)             /* wrap */
                return(EINVAL);

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

        map = &p->p_vmspace->vm_map;

        /*
         * map->token serializes extracting the address range for size == 0
         * msyncs with the vm_map_clean call; if the token were not held
         * across the two calls, an intervening munmap/mmap pair, for example,
         * could cause msync to occur on a wrong region.
         */
        lwkt_gettoken(&map->token);

        /*
         * 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);
                if (rv == FALSE) {
                        vm_map_unlock_read(map);
                        rv = KERN_INVALID_ADDRESS;
                        goto done;
                }
                addr = entry->start;
                size = entry->end - entry->start;
                vm_map_unlock_read(map);
        }

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

        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 system call handler
 *
 * munmap_args(void *addr, size_t len)
 *
 * No requirements
 */
int
sys_munmap(struct munmap_args *uap)
{
        struct proc *p = curproc;
        vm_offset_t addr;
        vm_offset_t tmpaddr;
        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 (size < uap->len)            /* wrap */
                return(EINVAL);
        tmpaddr = addr + size;          /* workaround gcc4 opt */
        if (tmpaddr < addr)             /* wrap */
                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_MAX_USER_ADDRESS > 0 && tmpaddr > VM_MAX_USER_ADDRESS)
                return (EINVAL);
        if (VM_MIN_USER_ADDRESS > 0 && addr < VM_MIN_USER_ADDRESS)
                return (EINVAL);

        map = &p->p_vmspace->vm_map;

        /* map->token serializes between the map check and the actual unmap */
        lwkt_gettoken(&map->token);

        /*
         * Make sure entire range is allocated.
         */
        if (!vm_map_check_protection(map, addr, addr + size,
                                     VM_PROT_NONE, FALSE)) {
                lwkt_reltoken(&map->token);
                return (EINVAL);
        }
        /* returns nothing but KERN_SUCCESS anyway */
        vm_map_remove(map, addr, addr + size);
        lwkt_reltoken(&map->token);
        return (0);
}

/*
 * mprotect_args(const void *addr, size_t len, int prot)
 *
 * No requirements.
 */
int
sys_mprotect(struct mprotect_args *uap)
{
        struct proc *p = curproc;
        vm_offset_t addr;
        vm_offset_t tmpaddr;
        vm_size_t size, pageoff;
        vm_prot_t prot;
        int error;

        addr = (vm_offset_t) uap->addr;
        size = uap->len;
        prot = uap->prot & VM_PROT_ALL;

        pageoff = (addr & PAGE_MASK);
        addr -= pageoff;
        size += pageoff;
        size = (vm_size_t) round_page(size);
        if (size < uap->len)            /* wrap */
                return(EINVAL);
        tmpaddr = addr + size;          /* workaround gcc4 opt */
        if (tmpaddr < addr)             /* wrap */
                return(EINVAL);

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

/*
 * minherit system call handler
 *
 * minherit_args(void *addr, size_t len, int inherit)
 *
 * No requirements.
 */
int
sys_minherit(struct minherit_args *uap)
{
        struct proc *p = curproc;
        vm_offset_t addr;
        vm_offset_t tmpaddr;
        vm_size_t size, pageoff;
        vm_inherit_t inherit;
        int error;

        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 (size < uap->len)            /* wrap */
                return(EINVAL);
        tmpaddr = addr + size;          /* workaround gcc4 opt */
        if (tmpaddr < addr)             /* wrap */
                return(EINVAL);

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

/*
 * madvise system call handler
 * 
 * madvise_args(void *addr, size_t len, int behav)
 *
 * No requirements.
 */
int
sys_madvise(struct madvise_args *uap)
{
        struct proc *p = curproc;
        vm_offset_t start, end;
        vm_offset_t tmpaddr = (vm_offset_t)uap->addr + uap->len;
        int error;

        /*
         * Check for illegal behavior
         */
        if (uap->behav < 0 || uap->behav >= MADV_CONTROL_END)
                return (EINVAL);
        /*
         * Check for illegal addresses.  Watch out for address wrap... Note
         * that VM_*_ADDRESS are not constants due to casts (argh).
         */
        if (tmpaddr < (vm_offset_t)uap->addr)
                return (EINVAL);
        if (VM_MAX_USER_ADDRESS > 0 && tmpaddr > VM_MAX_USER_ADDRESS)
                return (EINVAL);
        if (VM_MIN_USER_ADDRESS > 0 && uap->addr < VM_MIN_USER_ADDRESS)
                return (EINVAL);

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

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

/*
 * mcontrol system call handler
 *
 * mcontrol_args(void *addr, size_t len, int behav, off_t value)
 *
 * No requirements
 */
int
sys_mcontrol(struct mcontrol_args *uap)
{
        struct proc *p = curproc;
        vm_offset_t start, end;
        vm_offset_t tmpaddr = (vm_offset_t)uap->addr + uap->len;
        int error;

        /*
         * Check for illegal behavior
         */
        if (uap->behav < 0 || uap->behav > MADV_CONTROL_END)
                return (EINVAL);
        /*
         * Check for illegal addresses.  Watch out for address wrap... Note
         * that VM_*_ADDRESS are not constants due to casts (argh).
         */
        if (tmpaddr < (vm_offset_t) uap->addr)
                return (EINVAL);
        if (VM_MAX_USER_ADDRESS > 0 && tmpaddr > VM_MAX_USER_ADDRESS)
                return (EINVAL);
        if (VM_MIN_USER_ADDRESS > 0 && uap->addr < VM_MIN_USER_ADDRESS)
                return (EINVAL);

        /*
         * Since this routine is only advisory, we default to conservative
         * behavior.
         */
        start = trunc_page((vm_offset_t)uap->addr);
        end = round_page(tmpaddr);
        
        error = vm_map_madvise(&p->p_vmspace->vm_map, start, end,
                               uap->behav, uap->value);
        return (error);
}


/*
 * mincore system call handler
 *
 * mincore_args(const void *addr, size_t len, char *vec)
 *
 * No requirements
 */
int
sys_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 (end < addr)
                return (EINVAL);
        if (VM_MAX_USER_ADDRESS > 0 && end > VM_MAX_USER_ADDRESS)
                return (EINVAL);

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

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

        lwkt_gettoken(&map->token);
        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->maptype != VM_MAPTYPE_NORMAL &&
                    current->maptype != VM_MAPTYPE_VPAGETABLE) {
                        continue;
                }
                if (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.
                         *
                         * If we have to check the VM object, only mess
                         * around with normal maps.  Do not mess around
                         * with virtual page tables (XXX).
                         */
                        mincoreinfo = pmap_mincore(pmap, addr);
                        if (mincoreinfo == 0 &&
                            current->maptype == VM_MAPTYPE_NORMAL) {
                                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?
                                 *
                                 * XXX vm_token - legacy for pmap_ts_referenced
                                 *     in i386 and vkernel pmap code.
                                 */
                                lwkt_gettoken(&vm_token);
                                vm_object_hold(current->object.vm_object);
                                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;
                                        }
                                }
                                vm_object_drop(current->object.vm_object);
                                lwkt_reltoken(&vm_token);
                        }

                        /*
                         * 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) {
                                        error = EFAULT;
                                        goto done;
                                }
                                ++lastvecindex;
                        }

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

                        /*
                         * 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) {
                        error = EFAULT;
                        goto done;
                }
                ++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);

        error = 0;
done:
        lwkt_reltoken(&map->token);
        return (error);
}

/*
 * mlock system call handler
 *
 * mlock_args(const void *addr, size_t len)
 *
 * No requirements
 */
int
sys_mlock(struct mlock_args *uap)
{
        vm_offset_t addr;
        vm_offset_t tmpaddr;
        vm_size_t size, pageoff;
        struct thread *td = curthread;
        struct proc *p = td->td_proc;
        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);
        if (size < uap->len)            /* wrap */
                return(EINVAL);
        tmpaddr = addr + size;          /* workaround gcc4 opt */
        if (tmpaddr < addr)             /* wrap */
                return (EINVAL);

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

        /* 
         * We do not need to synchronize against other threads updating ucred;
         * they update p->ucred, which is synchronized into td_ucred ourselves.
         */
#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 = priv_check_cred(td->td_ucred, PRIV_ROOT, 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(int how)
 *
 * No requirements
 */
int
sys_mlockall(struct mlockall_args *uap)
{
        struct thread *td = curthread;
        struct proc *p = td->td_proc;
        vm_map_t map = &p->p_vmspace->vm_map;
        vm_map_entry_t entry;
        int how = uap->how;
        int rc = KERN_SUCCESS;

        if (((how & MCL_CURRENT) == 0) && ((how & MCL_FUTURE) == 0))
                return (EINVAL);

        rc = priv_check_cred(td->td_ucred, PRIV_ROOT, 0);
        if (rc) 
                return (rc);

        vm_map_lock(map);
        do {
                if (how & MCL_CURRENT) {
                        for(entry = map->header.next;
                            entry != &map->header;
                            entry = entry->next);

                        rc = ENOSYS;
                        break;
                }
        
                if (how & MCL_FUTURE)
                        map->flags |= MAP_WIREFUTURE;
        } while(0);
        vm_map_unlock(map);

        return (rc);
}

/*
 * munlockall(void)
 *
 *      Unwire all user-wired map entries, cancel MCL_FUTURE.
 *
 * No requirements
 */
int
sys_munlockall(struct munlockall_args *uap)
{
        struct thread *td = curthread;
        struct proc *p = td->td_proc;
        vm_map_t map = &p->p_vmspace->vm_map;
        vm_map_entry_t entry;
        int rc = KERN_SUCCESS;

        vm_map_lock(map);

        /* Clear MAP_WIREFUTURE to cancel mlockall(MCL_FUTURE) */
        map->flags &= ~MAP_WIREFUTURE;

retry:
        for (entry = map->header.next;
             entry != &map->header;
             entry = entry->next) {
                if ((entry->eflags & MAP_ENTRY_USER_WIRED) == 0)
                        continue;

                /*
                 * If we encounter an in-transition entry, we release the 
                 * map lock and retry the scan; we do not decrement any
                 * wired_count more than once because we do not touch
                 * any entries with MAP_ENTRY_USER_WIRED not set.
                 *
                 * There is a potential interleaving with concurrent
                 * mlockall()s here -- if we abort a scan, an mlockall()
                 * could start, wire a number of entries before our 
                 * current position in, and then stall itself on this
                 * or any other in-transition entry. If that occurs, when
                 * we resume, we will unwire those entries. 
                 */
                if (entry->eflags & MAP_ENTRY_IN_TRANSITION) {
                        entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP;
                        ++mycpu->gd_cnt.v_intrans_coll;
                        ++mycpu->gd_cnt.v_intrans_wait;
                        vm_map_transition_wait(map);
                        goto retry;
                }

                KASSERT(entry->wired_count > 0, 
                        ("wired_count was 0 with USER_WIRED set! %p", entry));
        
                /* Drop wired count, if it hits zero, unwire the entry */
                entry->eflags &= ~MAP_ENTRY_USER_WIRED;
                entry->wired_count--;
                if (entry->wired_count == 0)
                        vm_fault_unwire(map, entry);
        }

        map->timestamp++;
        vm_map_unlock(map);

        return (rc);
}

/*
 * munlock system call handler
 *
 * munlock_args(const void *addr, size_t len)
 *
 * No requirements
 */
int
sys_munlock(struct munlock_args *uap)
{
        struct thread *td = curthread;
        struct proc *p = td->td_proc;
        vm_offset_t addr;
        vm_offset_t tmpaddr;
        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);

        tmpaddr = addr + size;
        if (tmpaddr < addr)             /* wrap */
                return (EINVAL);

#ifndef pmap_wired_count
        error = priv_check(td, PRIV_ROOT);
        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.
 * 
 * No requirements
 */
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;
        vm_offset_t eaddr;
        vm_size_t   esize;
        vm_size_t   align;
        int (*uksmap)(cdev_t dev, vm_page_t fake);
        struct vnode *vp;
        struct thread *td = curthread;
        struct proc *p;
        int rv = KERN_SUCCESS;
        off_t objsize;
        int docow;
        int error;

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

        objsize = round_page(size);
        if (objsize < size)
                return (EINVAL);
        size = objsize;

        lwkt_gettoken(&map->token);
        
        /*
         * XXX messy code, fixme
         *
         * NOTE: Overflow checks require discrete statements or GCC4
         * will optimize it out.
         */
        if ((p = curproc) != NULL && map == &p->p_vmspace->vm_map) {
                esize = map->size + size;       /* workaround gcc4 opt */
                if (esize < map->size ||
                    esize > p->p_rlimit[RLIMIT_VMEM].rlim_cur) {
                        lwkt_reltoken(&map->token);
                        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.
         *
         * NOTE: Overflow checks require discrete statements or GCC4
         * will optimize it out.
         */
        if (foff & PAGE_MASK) {
                lwkt_reltoken(&map->token);
                return (EINVAL);
        }

        /*
         * Handle alignment.  For large memory maps it is possible
         * that the MMU can optimize the page table so align anything
         * that is a multiple of SEG_SIZE to SEG_SIZE.
         *
         * Also align any large mapping (bigger than 16x SG_SIZE) to a
         * SEG_SIZE address boundary.
         */
        if (flags & MAP_SIZEALIGN) {
                align = size;
                if ((align ^ (align - 1)) != (align << 1) - 1) {
                        lwkt_reltoken(&map->token);
                        return (EINVAL);
                }
        } else if ((flags & MAP_FIXED) == 0 &&
                   ((size & SEG_MASK) == 0 || size > SEG_SIZE * 16)) {
                align = SEG_SIZE;
        } else {
                align = PAGE_SIZE;
        }

        if ((flags & (MAP_FIXED | MAP_TRYFIXED)) == 0) {
                fitit = TRUE;
                *addr = round_page(*addr);
        } else {
                if (*addr != trunc_page(*addr)) {
                        lwkt_reltoken(&map->token);
                        return (EINVAL);
                }
                eaddr = *addr + size;
                if (eaddr < *addr) {
                        lwkt_reltoken(&map->token);
                        return (EINVAL);
                }
                fitit = FALSE;
                if ((flags & MAP_TRYFIXED) == 0)
                        vm_map_remove(map, *addr, *addr + size);
        }

        uksmap = NULL;

        /*
         * Lookup/allocate object.
         */
        if (flags & MAP_ANON) {
                /*
                 * Unnamed anonymous regions always start at 0.
                 */
                if (handle) {
                        /*
                         * Default memory object
                         */
                        object = default_pager_alloc(handle, objsize,
                                                     prot, foff);
                        if (object == NULL) {
                                lwkt_reltoken(&map->token);
                                return(ENOMEM);
                        }
                        docow = MAP_PREFAULT_PARTIAL;
                } else {
                        /*
                         * Implicit single instance of a default memory
                         * object, so we don't need a VM object yet.
                         */
                        foff = 0;
                        object = NULL;
                        docow = 0;
                }
                vp = NULL;
        } else {
                vp = (struct vnode *)handle;

                /*
                 * Non-anonymous mappings of VCHR (aka not /dev/zero)
                 * cannot specify MAP_STACK or MAP_VPAGETABLE.
                 */
                if (vp->v_type == VCHR) {
                        if (flags & (MAP_STACK | MAP_VPAGETABLE)) {
                                lwkt_reltoken(&map->token);
                                return(EINVAL);
                        }
                }

                if (vp->v_type == VCHR && vp->v_rdev->si_ops->d_uksmap) {
                        /*
                         * Device mappings without a VM object, typically
                         * sharing permanently allocated kernel memory or
                         * process-context-specific (per-process) data.
                         *
                         * Force them to be shared.
                         */
                        uksmap = vp->v_rdev->si_ops->d_uksmap;
                        object = NULL;
                        docow = MAP_PREFAULT_PARTIAL;
                        flags &= ~(MAP_PRIVATE|MAP_COPY);
                        flags |= MAP_SHARED;
                } else if (vp->v_type == VCHR) {
                        /*
                         * Device mappings (device size unknown?).
                         * Force them to be shared.
                         */
                        error = dev_dmmap_single(vp->v_rdev, &foff, objsize,
                                                &object, prot, NULL);

                        if (error == ENODEV) {
                                handle = (void *)(intptr_t)vp->v_rdev;
                                object = dev_pager_alloc(handle, objsize, prot, foff);
                                if (object == NULL) {
                                        lwkt_reltoken(&map->token);
                                        return(EINVAL);
                                }
                        } else if (error) {
                                lwkt_reltoken(&map->token);
                                return(error);
                        }

                        docow = MAP_PREFAULT_PARTIAL;
                        flags &= ~(MAP_PRIVATE|MAP_COPY);
                        flags |= MAP_SHARED;
                } else {
                        /*
                         * Regular file mapping (typically).  The attribute
                         * check is for the link count test only.  mmapable
                         * vnodes must already have a VM object assigned.
                         */
                        struct vattr vat;
                        int error;

                        error = VOP_GETATTR(vp, &vat);
                        if (error) {
                                lwkt_reltoken(&map->token);
                                return (error);
                        }
                        docow = MAP_PREFAULT_PARTIAL;
                        object = vnode_pager_reference(vp);
                        if (object == NULL && vp->v_type == VREG) {
                                lwkt_reltoken(&map->token);
                                kprintf("Warning: cannot mmap vnode %p, no "
                                        "object\n", vp);
                                return(EINVAL);
                        }

                        /*
                         * 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;
                        }
                }
        }

        /*
         * Deal with the adjusted flags
         */
        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;

        /*
         * This may place the area in its own page directory if (size) is
         * large enough, otherwise it typically returns its argument.
         *
         * (object can be NULL)
         */
        if (fitit) {
                *addr = pmap_addr_hint(object, *addr, size);
        }

        /*
         * Stack mappings need special attention.
         *
         * Mappings that use virtual page tables will default to storing
         * the page table at offset 0.
         */
        if (uksmap) {
                rv = vm_map_find(map, uksmap, vp->v_rdev,
                                 foff, addr, size,
                                 align, fitit,
                                 VM_MAPTYPE_UKSMAP, VM_SUBSYS_MMAP,
                                 prot, maxprot, docow);
        } else if (flags & MAP_STACK) {
                rv = vm_map_stack(map, *addr, size, flags,
                                  prot, maxprot, docow);
        } else if (flags & MAP_VPAGETABLE) {
                rv = vm_map_find(map, object, NULL,
                                 foff, addr, size,
                                 align, fitit,
                                 VM_MAPTYPE_VPAGETABLE, VM_SUBSYS_MMAP,
                                 prot, maxprot, docow);
        } else {
                rv = vm_map_find(map, object, NULL,
                                 foff, addr, size,
                                 align, fitit,
                                 VM_MAPTYPE_NORMAL, VM_SUBSYS_MMAP,
                                 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.
                 *
                 * (NOTE: object can be NULL)
                 */
                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) {
                        vm_map_remove(map, *addr, *addr + size);
                        goto out;
                }
        }

        /* If a process has marked all future mappings for wiring, do so */
        if ((rv == KERN_SUCCESS) && (map->flags & MAP_WIREFUTURE))
                vm_map_unwire(map, *addr, *addr + size, FALSE);

        /*
         * Set the access time on the vnode
         */
        if (vp != NULL)
                vn_mark_atime(vp, td);
out:
        lwkt_reltoken(&map->token);
        
        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);
        }
}

/*
 * Translate a Mach VM return code to zero on success or the appropriate errno
 * on failure.
 */
int
vm_mmap_to_errno(int rv)
{

        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);
        }
}