[apple/xnu.git] / osfmk / kern / ipc_tt.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */

/*
 * File:        ipc_tt.c
 * Purpose:
 *      Task and thread related IPC functions.
 */

#include <mach/boolean.h>
#include <mach_rt.h>
#include <mach/kern_return.h>
#include <mach/mach_param.h>
#include <mach/task_special_ports.h>
#include <mach/thread_special_ports.h>
#include <mach/thread_status.h>
#include <mach/exception_types.h>
#include <mach/mach_traps.h>
#include <mach/task_server.h>
#include <mach/thread_act_server.h>
#include <mach/mach_host_server.h>
#include <mach/vm_map_server.h>
#include <kern/host.h>
#include <kern/ipc_tt.h>
#include <kern/thread_act.h>
#include <kern/misc_protos.h>
#include <vm/vm_pageout.h>

/*
 *      Routine:        ipc_task_init
 *      Purpose:
 *              Initialize a task's IPC state.
 *
 *              If non-null, some state will be inherited from the parent.
 *              The parent must be appropriately initialized.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_task_init(
        task_t          task,
        task_t          parent)
{
        ipc_space_t space;
        ipc_port_t kport;
        kern_return_t kr;
        int i;


        kr = ipc_space_create(&ipc_table_entries[0], &space);
        if (kr != KERN_SUCCESS)
                panic("ipc_task_init");


        kport = ipc_port_alloc_kernel();
        if (kport == IP_NULL)
                panic("ipc_task_init");

        itk_lock_init(task);
        task->itk_self = kport;
        task->itk_sself = ipc_port_make_send(kport);
        task->itk_space = space;
        space->is_fast = task->kernel_loaded;

        if (parent == TASK_NULL) {
                for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                        task->exc_actions[i].port = IP_NULL;
                }/* for */
                task->exc_actions[EXC_MACH_SYSCALL].port = 
                        ipc_port_make_send(realhost.host_self);
                task->itk_host = ipc_port_make_send(realhost.host_self);
                task->itk_bootstrap = IP_NULL;
                for (i = 0; i < TASK_PORT_REGISTER_MAX; i++)
                        task->itk_registered[i] = IP_NULL;
        } else {
                itk_lock(parent);
                assert(parent->itk_self != IP_NULL);

                /* inherit registered ports */

                for (i = 0; i < TASK_PORT_REGISTER_MAX; i++)
                        task->itk_registered[i] =
                                ipc_port_copy_send(parent->itk_registered[i]);

                /* inherit exception and bootstrap ports */

                for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                    task->exc_actions[i].port =
                                ipc_port_copy_send(parent->exc_actions[i].port);
                    task->exc_actions[i].flavor =
                                parent->exc_actions[i].flavor;
                    task->exc_actions[i].behavior = 
                                parent->exc_actions[i].behavior;
                }/* for */
                task->itk_host =
                        ipc_port_copy_send(parent->itk_host);

                task->itk_bootstrap =
                        ipc_port_copy_send(parent->itk_bootstrap);

                itk_unlock(parent);
        }
}

/*
 *      Routine:        ipc_task_enable
 *      Purpose:
 *              Enable a task for IPC access.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_task_enable(
        task_t          task)
{
        ipc_port_t kport;

        itk_lock(task);
        kport = task->itk_self;
        if (kport != IP_NULL)
                ipc_kobject_set(kport, (ipc_kobject_t) task, IKOT_TASK);
        itk_unlock(task);
}

/*
 *      Routine:        ipc_task_disable
 *      Purpose:
 *              Disable IPC access to a task.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_task_disable(
        task_t          task)
{
        ipc_port_t kport;

        itk_lock(task);
        kport = task->itk_self;
        if (kport != IP_NULL)
                ipc_kobject_set(kport, IKO_NULL, IKOT_NONE);
        itk_unlock(task);
}

/*
 *      Routine:        ipc_task_terminate
 *      Purpose:
 *              Clean up and destroy a task's IPC state.
 *      Conditions:
 *              Nothing locked.  The task must be suspended.
 *              (Or the current thread must be in the task.)
 */

void
ipc_task_terminate(
        task_t          task)
{
        ipc_port_t kport;
        int i;

        itk_lock(task);
        kport = task->itk_self;

        if (kport == IP_NULL) {
                /* the task is already terminated (can this happen?) */
                itk_unlock(task);
                return;
        }

        task->itk_self = IP_NULL;
        itk_unlock(task);

        /* release the naked send rights */

        if (IP_VALID(task->itk_sself))
                ipc_port_release_send(task->itk_sself);

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                if (IP_VALID(task->exc_actions[i].port)) {
                        ipc_port_release_send(task->exc_actions[i].port);
                }
        }/* for */
        if (IP_VALID(task->itk_host))
                ipc_port_release_send(task->itk_host);

        if (IP_VALID(task->itk_bootstrap))
                ipc_port_release_send(task->itk_bootstrap);

        for (i = 0; i < TASK_PORT_REGISTER_MAX; i++)
                if (IP_VALID(task->itk_registered[i]))
                        ipc_port_release_send(task->itk_registered[i]);

        ipc_port_release_send(task->wired_ledger_port);
        ipc_port_release_send(task->paged_ledger_port);

        /* destroy the kernel port */
        ipc_port_dealloc_kernel(kport);
}

/*
 *      Routine:        ipc_thread_init
 *      Purpose:
 *              Initialize a thread's IPC state.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_thread_init(
        thread_t        thread)
{
        ipc_kmsg_queue_init(&thread->ith_messages);
        thread->ith_mig_reply = MACH_PORT_NULL;
        thread->ith_rpc_reply = IP_NULL;
}

/*
 *      Routine:        ipc_thread_terminate
 *      Purpose:
 *              Clean up and destroy a thread's IPC state.
 *      Conditions:
 *              Nothing locked.  The thread must be suspended.
 *              (Or be the current thread.)
 */

void
ipc_thread_terminate(
        thread_t        thread)
{
        assert(ipc_kmsg_queue_empty(&thread->ith_messages));

        if (thread->ith_rpc_reply != IP_NULL)
            ipc_port_dealloc_reply(thread->ith_rpc_reply);
        thread->ith_rpc_reply = IP_NULL;
}

/*
 *      Routine:        ipc_thr_act_init
 *      Purpose:
 *              Initialize an thr_act's IPC state.
 *      Conditions:
 *              Nothing locked.
 */

void
ipc_thr_act_init(task_t task, thread_act_t thr_act)
{
        ipc_port_t kport; int i;

        kport = ipc_port_alloc_kernel();
        if (kport == IP_NULL)
                panic("ipc_thr_act_init");

        thr_act->ith_self = kport;
        thr_act->ith_sself = ipc_port_make_send(kport);

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++)
                thr_act->exc_actions[i].port = IP_NULL;

        thr_act->exc_actions[EXC_MACH_SYSCALL].port =
                                        ipc_port_make_send(realhost.host_self);

        ipc_kobject_set(kport, (ipc_kobject_t) thr_act, IKOT_ACT);
}

void
ipc_thr_act_disable(thread_act_t thr_act)
{
        int i;
        ipc_port_t kport;

        kport = thr_act->ith_self;

        if (kport != IP_NULL)
                ipc_kobject_set(kport, IKO_NULL, IKOT_NONE);
}

void
ipc_thr_act_terminate(thread_act_t thr_act)
{
        ipc_port_t kport; int i;

        kport = thr_act->ith_self;

        if (kport == IP_NULL) {
                /* the thread is already terminated (can this happen?) */
                return;
        }

        thr_act->ith_self = IP_NULL;

        /* release the naked send rights */

        if (IP_VALID(thr_act->ith_sself))
                ipc_port_release_send(thr_act->ith_sself);
        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
            if (IP_VALID(thr_act->exc_actions[i].port))
                ipc_port_release_send(thr_act->exc_actions[i].port);
        }

        /* destroy the kernel port */
        ipc_port_dealloc_kernel(kport);
}

/*
 *      Routine:        retrieve_task_self_fast
 *      Purpose:
 *              Optimized version of retrieve_task_self,
 *              that only works for the current task.
 *
 *              Return a send right (possibly null/dead)
 *              for the task's user-visible self port.
 *      Conditions:
 *              Nothing locked.
 */

ipc_port_t
retrieve_task_self_fast(
        register task_t         task)
{
        register ipc_port_t port;

        assert(task == current_task());

        itk_lock(task);
        assert(task->itk_self != IP_NULL);

        if ((port = task->itk_sself) == task->itk_self) {
                /* no interposing */

                ip_lock(port);
                assert(ip_active(port));
                ip_reference(port);
                port->ip_srights++;
                ip_unlock(port);
        } else
                port = ipc_port_copy_send(port);
        itk_unlock(task);

        return port;
}

/*
 *      Routine:        retrieve_act_self_fast
 *      Purpose:
 *              Optimized version of retrieve_thread_self,
 *              that only works for the current thread.
 *
 *              Return a send right (possibly null/dead)
 *              for the thread's user-visible self port.
 *      Conditions:
 *              Nothing locked.
 */

ipc_port_t
retrieve_act_self_fast(thread_act_t thr_act)
{
        register ipc_port_t port;

        assert(thr_act == current_act());
        act_lock(thr_act);
        assert(thr_act->ith_self != IP_NULL);

        if ((port = thr_act->ith_sself) == thr_act->ith_self) {
                /* no interposing */

                ip_lock(port);
                assert(ip_active(port));
                ip_reference(port);
                port->ip_srights++;
                ip_unlock(port);
        } else
                port = ipc_port_copy_send(port);
        act_unlock(thr_act);

        return port;
}

/*
 *      Routine:        task_self_trap [mach trap]
 *      Purpose:
 *              Give the caller send rights for his own task port.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              MACH_PORT_NULL if there are any resource failures
 *              or other errors.
 */

mach_port_name_t
task_self_trap(void)
{
        task_t task = current_task();
        ipc_port_t sright;

        sright = retrieve_task_self_fast(task);
        return ipc_port_copyout_send(sright, task->itk_space);
}

/*
 *      Routine:        thread_self_trap [mach trap]
 *      Purpose:
 *              Give the caller send rights for his own thread port.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              MACH_PORT_NULL if there are any resource failures
 *              or other errors.
 */

mach_port_name_t
thread_self_trap(void)
{
        thread_act_t  thr_act  = current_act();
        task_t task = thr_act->task;
        ipc_port_t sright;

        sright = retrieve_act_self_fast(thr_act);
        return ipc_port_copyout_send(sright, task->itk_space);
}

/*
 *      Routine:        mach_reply_port [mach trap]
 *      Purpose:
 *              Allocate a port for the caller.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              MACH_PORT_NULL if there are any resource failures
 *              or other errors.
 */

mach_port_name_t
mach_reply_port(void)
{
        ipc_port_t port;
        mach_port_name_t name;
        kern_return_t kr;

        kr = ipc_port_alloc(current_task()->itk_space, &name, &port);
        if (kr == KERN_SUCCESS)
                ip_unlock(port);
        else
                name = MACH_PORT_NULL;

        return name;
}

/*
 *      Routine:        task_get_special_port [kernel call]
 *      Purpose:
 *              Clones a send right for one of the task's
 *              special ports.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Extracted a send right.
 *              KERN_INVALID_ARGUMENT   The task is null.
 *              KERN_FAILURE            The task/space is dead.
 *              KERN_INVALID_ARGUMENT   Invalid special port.
 */

kern_return_t
task_get_special_port(
        task_t          task,
        int             which,
        ipc_port_t      *portp)
{
        ipc_port_t *whichp;
        ipc_port_t port;

        if (task == TASK_NULL)
                return KERN_INVALID_ARGUMENT;

        switch (which) {
            case TASK_KERNEL_PORT:
                whichp = &task->itk_sself;
                break;

            case TASK_HOST_PORT:
                whichp = &task->itk_host;
                break;

            case TASK_BOOTSTRAP_PORT:
                whichp = &task->itk_bootstrap;
                break;

            case TASK_WIRED_LEDGER_PORT:
                whichp = &task->wired_ledger_port;
                break;

            case TASK_PAGED_LEDGER_PORT:
                whichp = &task->paged_ledger_port;
                break;
                    
            default:
                return KERN_INVALID_ARGUMENT;
        }

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);
                return KERN_FAILURE;
        }

        port = ipc_port_copy_send(*whichp);
        itk_unlock(task);

        *portp = port;
        return KERN_SUCCESS;
}

/*
 *      Routine:        task_set_special_port [kernel call]
 *      Purpose:
 *              Changes one of the task's special ports,
 *              setting it to the supplied send right.
 *      Conditions:
 *              Nothing locked.  If successful, consumes
 *              the supplied send right.
 *      Returns:
 *              KERN_SUCCESS            Changed the special port.
 *              KERN_INVALID_ARGUMENT   The task is null.
 *              KERN_FAILURE            The task/space is dead.
 *              KERN_INVALID_ARGUMENT   Invalid special port.
 */

kern_return_t
task_set_special_port(
        task_t          task,
        int             which,
        ipc_port_t      port)
{
        ipc_port_t *whichp;
        ipc_port_t old;

        if (task == TASK_NULL)
                return KERN_INVALID_ARGUMENT;

        switch (which) {
            case TASK_KERNEL_PORT:
                whichp = &task->itk_sself;
                break;

            case TASK_HOST_PORT:
                whichp = &task->itk_host;
                break;

            case TASK_BOOTSTRAP_PORT:
                whichp = &task->itk_bootstrap;
                break;

            case TASK_WIRED_LEDGER_PORT:
                whichp = &task->wired_ledger_port;
                break;

            case TASK_PAGED_LEDGER_PORT:
                whichp = &task->paged_ledger_port;
                break;
                    
            default:
                return KERN_INVALID_ARGUMENT;
        }/* switch */

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);
                return KERN_FAILURE;
        }

        old = *whichp;
        *whichp = port;
        itk_unlock(task);

        if (IP_VALID(old))
                ipc_port_release_send(old);
        return KERN_SUCCESS;
}


/*
 *      Routine:        mach_ports_register [kernel call]
 *      Purpose:
 *              Stash a handful of port send rights in the task.
 *              Child tasks will inherit these rights, but they
 *              must use mach_ports_lookup to acquire them.
 *
 *              The rights are supplied in a (wired) kalloc'd segment.
 *              Rights which aren't supplied are assumed to be null.
 *      Conditions:
 *              Nothing locked.  If successful, consumes
 *              the supplied rights and memory.
 *      Returns:
 *              KERN_SUCCESS            Stashed the port rights.
 *              KERN_INVALID_ARGUMENT   The task is null.
 *              KERN_INVALID_ARGUMENT   The task is dead.
 *              KERN_INVALID_ARGUMENT   Too many port rights supplied.
 */

kern_return_t
mach_ports_register(
        task_t                  task,
        mach_port_array_t       memory,
        mach_msg_type_number_t  portsCnt)
{
        ipc_port_t ports[TASK_PORT_REGISTER_MAX];
        int i;

        if ((task == TASK_NULL) ||
            (portsCnt > TASK_PORT_REGISTER_MAX))
                return KERN_INVALID_ARGUMENT;

        /*
         *      Pad the port rights with nulls.
         */

        for (i = 0; i < portsCnt; i++)
                ports[i] = memory[i];
        for (; i < TASK_PORT_REGISTER_MAX; i++)
                ports[i] = IP_NULL;

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);
                return KERN_INVALID_ARGUMENT;
        }

        /*
         *      Replace the old send rights with the new.
         *      Release the old rights after unlocking.
         */

        for (i = 0; i < TASK_PORT_REGISTER_MAX; i++) {
                ipc_port_t old;

                old = task->itk_registered[i];
                task->itk_registered[i] = ports[i];
                ports[i] = old;
        }

        itk_unlock(task);

        for (i = 0; i < TASK_PORT_REGISTER_MAX; i++)
                if (IP_VALID(ports[i]))
                        ipc_port_release_send(ports[i]);

        /*
         *      Now that the operation is known to be successful,
         *      we can free the memory.
         */

        if (portsCnt != 0)
                kfree((vm_offset_t) memory,
                      (vm_size_t) (portsCnt * sizeof(mach_port_t)));

        return KERN_SUCCESS;
}

/*
 *      Routine:        mach_ports_lookup [kernel call]
 *      Purpose:
 *              Retrieves (clones) the stashed port send rights.
 *      Conditions:
 *              Nothing locked.  If successful, the caller gets
 *              rights and memory.
 *      Returns:
 *              KERN_SUCCESS            Retrieved the send rights.
 *              KERN_INVALID_ARGUMENT   The task is null.
 *              KERN_INVALID_ARGUMENT   The task is dead.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
mach_ports_lookup(
        task_t                  task,
        mach_port_array_t       *portsp,
        mach_msg_type_number_t  *portsCnt)
{
        vm_offset_t memory;
        vm_size_t size;
        ipc_port_t *ports;
        int i;

        kern_return_t kr;
        
        if (task == TASK_NULL)
                return KERN_INVALID_ARGUMENT;

        size = (vm_size_t) (TASK_PORT_REGISTER_MAX * sizeof(ipc_port_t));

        memory = kalloc(size);
        if (memory == 0)
                return KERN_RESOURCE_SHORTAGE;

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);

                kfree(memory, size);
                return KERN_INVALID_ARGUMENT;
        }

        ports = (ipc_port_t *) memory;

        /*
         *      Clone port rights.  Because kalloc'd memory
         *      is wired, we won't fault while holding the task lock.
         */

        for (i = 0; i < TASK_PORT_REGISTER_MAX; i++)
                ports[i] = ipc_port_copy_send(task->itk_registered[i]);

        itk_unlock(task);

        *portsp = (mach_port_array_t) ports;
        *portsCnt = TASK_PORT_REGISTER_MAX;
        return KERN_SUCCESS;
}

/*
 *      Routine: convert_port_to_locked_task
 *      Purpose:
 *              Internal helper routine to convert from a port to a locked
 *              task.  Used by several routines that try to convert from a
 *              task port to a reference on some task related object.
 *      Conditions:
 *              Nothing locked, blocking OK.
 */
task_t
convert_port_to_locked_task(ipc_port_t port)
{
        while (IP_VALID(port)) {
                task_t task;

                ip_lock(port);
                if (!ip_active(port) || (ip_kotype(port) != IKOT_TASK)) {
                        ip_unlock(port);
                        return TASK_NULL;
                }
                task = (task_t) port->ip_kobject;
                assert(task != TASK_NULL);

                /*
                 * Normal lock ordering puts task_lock() before ip_lock().
                 * Attempt out-of-order locking here.
                 */
                if (task_lock_try(task)) {
                        ip_unlock(port);
                        return(task);
                }

                ip_unlock(port);
                mutex_pause();
        }
        return TASK_NULL;
}

/*
 *      Routine:        convert_port_to_task
 *      Purpose:
 *              Convert from a port to a task.
 *              Doesn't consume the port ref; produces a task ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */
task_t
convert_port_to_task(
        ipc_port_t      port)
{
        task_t task;

        task = convert_port_to_locked_task(port);
        if (task) {
                task->ref_count++;
                task_unlock(task);
        }
        return task;
}

/*
 *      Routine:        convert_port_to_space
 *      Purpose:
 *              Convert from a port to a space.
 *              Doesn't consume the port ref; produces a space ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */
ipc_space_t
convert_port_to_space(
        ipc_port_t      port)
{
        ipc_space_t space;
        task_t task;

        task = convert_port_to_locked_task(port);

        if (task == TASK_NULL)
                return IPC_SPACE_NULL;

        if (!task->active) {
                task_unlock(task);
                return IPC_SPACE_NULL;
        }
                
        space = task->itk_space;
        is_reference(space);
        task_unlock(task);
        return (space);
}

upl_t
convert_port_to_upl(
        ipc_port_t      port)
{
        upl_t upl;

        ip_lock(port);
        if (!ip_active(port) || (ip_kotype(port) != IKOT_UPL)) {
                        ip_unlock(port);
                        return (upl_t)NULL;
        }
        upl = (upl_t) port->ip_kobject;
        ip_unlock(port);
        upl_lock(upl);
        upl->ref_count+=1;
        upl_unlock(upl);
        return upl;
}

mach_port_t
convert_upl_to_port(
        upl_t           upl)
{
        return MACH_PORT_NULL;
}

__private_extern__ void
upl_no_senders(
        upl_t                   upl,
        mach_port_mscount_t     mscount)
{
        return;
}

/*
 *      Routine:        convert_port_entry_to_map
 *      Purpose:
 *              Convert from a port specifying an entry or a task
 *              to a map. Doesn't consume the port ref; produces a map ref,
 *              which may be null.  Unlike convert_port_to_map, the
 *              port may be task or a named entry backed.
 *      Conditions:
 *              Nothing locked.
 */


vm_map_t
convert_port_entry_to_map(
        ipc_port_t      port)
{
        task_t task;
        vm_map_t map;
        vm_named_entry_t        named_entry;

        if(IP_VALID(port) && (ip_kotype(port) == IKOT_NAMED_ENTRY)) {
                while(TRUE) {
                        ip_lock(port);
                        if(ip_active(port) && (ip_kotype(port) 
                                                == IKOT_NAMED_ENTRY)) {
                                named_entry =
                                         (vm_named_entry_t)port->ip_kobject;
                                if (!(mutex_try(&(named_entry)->Lock))) {
                                        ip_unlock(port);
                                        mutex_pause();
                                        continue;
                                }
                                named_entry->ref_count++;
                                mutex_unlock(&(named_entry)->Lock);
                                ip_unlock(port);
                                if ((named_entry->is_sub_map) &&
                                        (named_entry->protection 
                                        & VM_PROT_WRITE)) {
                                        map = named_entry->backing.map;
                                } else {
                                        mach_destroy_memory_entry(port);
                                        return VM_MAP_NULL;
                                }
                                vm_map_reference_swap(map);
                                mach_destroy_memory_entry(port);
                                break;
                        }
                        else 
                                return VM_MAP_NULL;
                }
        } else {
                task_t task;

                task = convert_port_to_locked_task(port);
                
                if (task == TASK_NULL)
                        return VM_MAP_NULL;

                if (!task->active) {
                        task_unlock(task);
                        return VM_MAP_NULL;
                }
                
                map = task->map;
                vm_map_reference_swap(map);
                task_unlock(task);
        }

        return map;
}

/*
 *      Routine:        convert_port_entry_to_object
 *      Purpose:
 *              Convert from a port specifying a named entry to an
 *              object. Doesn't consume the port ref; produces a map ref,
 *              which may be null. 
 *      Conditions:
 *              Nothing locked.
 */


vm_object_t
convert_port_entry_to_object(
        ipc_port_t      port)
{
        vm_object_t object;
        vm_named_entry_t        named_entry;

        if(IP_VALID(port) && (ip_kotype(port) == IKOT_NAMED_ENTRY)) {
                while(TRUE) {
                        ip_lock(port);
                        if(ip_active(port) && (ip_kotype(port) 
                                                == IKOT_NAMED_ENTRY)) {
                                named_entry =
                                         (vm_named_entry_t)port->ip_kobject;
                                if (!(mutex_try(&(named_entry)->Lock))) {
                                        ip_unlock(port);
                                        mutex_pause();
                                        continue;
                                }
                                named_entry->ref_count++;
                                mutex_unlock(&(named_entry)->Lock);
                                ip_unlock(port);
                                if ((!named_entry->is_sub_map) &&
                                        (named_entry->protection 
                                        & VM_PROT_WRITE)) {
                                        object = named_entry->object;
                                } else {
                                        mach_destroy_memory_entry(port);
                                        return (vm_object_t)NULL;
                                }
                                vm_object_reference(named_entry->object);
                                mach_destroy_memory_entry(port);
                                break;
                        }
                        else 
                                return (vm_object_t)NULL;
                }
        } else {
                return (vm_object_t)NULL;
        }

        return object;
}

/*
 *      Routine:        convert_port_to_map
 *      Purpose:
 *              Convert from a port to a map.
 *              Doesn't consume the port ref; produces a map ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */

vm_map_t
convert_port_to_map(
        ipc_port_t      port)
{
        task_t task;
        vm_map_t map;

        task = convert_port_to_locked_task(port);
                
        if (task == TASK_NULL)
                return VM_MAP_NULL;

        if (!task->active) {
                task_unlock(task);
                return VM_MAP_NULL;
        }
                
        map = task->map;
        vm_map_reference_swap(map);
        task_unlock(task);
        return map;
}


/*
 *      Routine:        convert_port_to_act
 *      Purpose:
 *              Convert from a port to a thr_act.
 *              Doesn't consume the port ref; produces an thr_act ref,
 *              which may be null.
 *      Conditions:
 *              Nothing locked.
 */

thread_act_t
convert_port_to_act( ipc_port_t port )
{
        boolean_t r;
        thread_act_t thr_act = 0;

        r = FALSE;
        while (!r && IP_VALID(port)) {
                ip_lock(port);
                r = ref_act_port_locked(port, &thr_act);
                /* port unlocked */
        }
        return (thr_act);
}

boolean_t
ref_act_port_locked( ipc_port_t port, thread_act_t *pthr_act )
{
        thread_act_t thr_act;

        thr_act = 0;
        if (ip_active(port) &&
                (ip_kotype(port) == IKOT_ACT)) {
                thr_act = (thread_act_t) port->ip_kobject;
                assert(thr_act != THR_ACT_NULL);

                /*
                 * Normal lock ordering is act_lock(), then ip_lock().
                 * Allow out-of-order locking here, using
                 * act_reference_act_locked() to accomodate it.
                 */
                if (!act_lock_try(thr_act)) {
                        ip_unlock(port);
                        mutex_pause();
                        return (FALSE);
                }
                act_locked_act_reference(thr_act);
                act_unlock(thr_act);
        }
        *pthr_act = thr_act;
        ip_unlock(port);
        return (TRUE);
}

/*
 *      Routine:        port_name_to_act
 *      Purpose:
 *              Convert from a port name to an act reference
 *              A name of MACH_PORT_NULL is valid for the null act
 *      Conditions:
 *              Nothing locked.
 */
thread_act_t
port_name_to_act(
        mach_port_name_t        name)
{
        thread_act_t thr_act = THR_ACT_NULL;
        ipc_port_t kern_port;
        kern_return_t kr;

        if (MACH_PORT_VALID(name)) {
                kr = ipc_object_copyin(current_space(), name,
                                       MACH_MSG_TYPE_COPY_SEND,
                                       (ipc_object_t *) &kern_port);
                if (kr != KERN_SUCCESS)
                        return THR_ACT_NULL;

                thr_act = convert_port_to_act(kern_port);
                
                if (IP_VALID(kern_port))
                        ipc_port_release_send(kern_port);
        }
        return thr_act;
}

task_t
port_name_to_task(
        mach_port_name_t name)
{
        ipc_port_t kern_port;
        kern_return_t kr;
        task_t task = TASK_NULL;

        if (MACH_PORT_VALID(name)) {
                kr = ipc_object_copyin(current_space(), name,
                                       MACH_MSG_TYPE_COPY_SEND,
                                       (ipc_object_t *) &kern_port);
                if (kr != KERN_SUCCESS)
                        return TASK_NULL;

                task = convert_port_to_task(kern_port);

                if (IP_VALID(kern_port))
                        ipc_port_release_send(kern_port);
        }
        return task;
}

/*
 *      Routine:        convert_task_to_port
 *      Purpose:
 *              Convert from a task to a port.
 *              Consumes a task ref; produces a naked send right
 *              which may be invalid.  
 *      Conditions:
 *              Nothing locked.
 */

ipc_port_t
convert_task_to_port(
        task_t          task)
{
        ipc_port_t port;

        itk_lock(task);
        if (task->itk_self != IP_NULL)
#if     NORMA_TASK
                if (task->map == VM_MAP_NULL)
                        /* norma placeholder task */
                        port = ipc_port_copy_send(task->itk_self);
                else
#endif  /* NORMA_TASK */
                port = ipc_port_make_send(task->itk_self);
        else
                port = IP_NULL;
        itk_unlock(task);

        task_deallocate(task);
        return port;
}

/*
 *      Routine:        convert_act_to_port
 *      Purpose:
 *              Convert from a thr_act to a port.
 *              Consumes an thr_act ref; produces a naked send right
 *              which may be invalid.
 *      Conditions:
 *              Nothing locked.
 */

ipc_port_t
convert_act_to_port(thr_act)
        thread_act_t thr_act;
{
        ipc_port_t port;

        act_lock(thr_act);
        if (thr_act->ith_self != IP_NULL)
                port = ipc_port_make_send(thr_act->ith_self);
        else
                port = IP_NULL;
        act_unlock(thr_act);

        act_deallocate(thr_act);
        return port;
}

/*
 *      Routine:        space_deallocate
 *      Purpose:
 *              Deallocate a space ref produced by convert_port_to_space.
 *      Conditions:
 *              Nothing locked.
 */

void
space_deallocate(
        ipc_space_t     space)
{
        if (space != IS_NULL)
                is_release(space);
}

/*
 *      Routine:        thread/task_set_exception_ports [kernel call]
 *      Purpose:
 *                      Sets the thread/task exception port, flavor and
 *                      behavior for the exception types specified by the mask.
 *                      There will be one send right per exception per valid
 *                      port.
 *      Conditions:
 *              Nothing locked.  If successful, consumes
 *              the supplied send right.
 *      Returns:
 *              KERN_SUCCESS            Changed the special port.
 *              KERN_INVALID_ARGUMENT   The thread is null,
 *                                      Illegal mask bit set.
 *                                      Illegal exception behavior
 *              KERN_FAILURE            The thread is dead.
 */

kern_return_t
thread_set_exception_ports(
        thread_act_t                    thr_act,
        exception_mask_t                exception_mask,
        ipc_port_t                      new_port,
        exception_behavior_t            new_behavior,
        thread_state_flavor_t           new_flavor)
{
        register int    i;
        ipc_port_t      old_port[EXC_TYPES_COUNT];

        if (!thr_act)
                return KERN_INVALID_ARGUMENT;

        if (exception_mask & ~EXC_MASK_ALL)
                return KERN_INVALID_ARGUMENT;

        if (IP_VALID(new_port)) {
                switch (new_behavior) {
                case EXCEPTION_DEFAULT:
                case EXCEPTION_STATE:
                case EXCEPTION_STATE_IDENTITY:
                        break;
                default:
                        return KERN_INVALID_ARGUMENT;
                }
        }

        /* 
         * Check the validity of the thread_state_flavor by calling the
         * VALID_THREAD_STATE_FLAVOR architecture dependent macro defined in
         * osfmk/mach/ARCHITECTURE/thread_status.h
         */
        if (!VALID_THREAD_STATE_FLAVOR(new_flavor)) {
                return KERN_INVALID_ARGUMENT;
        }

        act_lock(thr_act);
        if (!thr_act->active) {
                act_unlock(thr_act);
                return KERN_FAILURE;
        }

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                if (exception_mask & (1 << i)) {
                        old_port[i] = thr_act->exc_actions[i].port;
                        thr_act->exc_actions[i].port =
                                ipc_port_copy_send(new_port);
                        thr_act->exc_actions[i].behavior = new_behavior;
                        thr_act->exc_actions[i].flavor = new_flavor;
                } else
                        old_port[i] = IP_NULL;
        }/* for */
        /*
         * Consume send rights without any lock held.
         */
        act_unlock(thr_act);
        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++)
                if (IP_VALID(old_port[i]))
                        ipc_port_release_send(old_port[i]);
        if (IP_VALID(new_port))          /* consume send right */
                ipc_port_release_send(new_port);

        return KERN_SUCCESS;
}/* thread_set_exception_port */

kern_return_t
task_set_exception_ports(
        task_t                          task,
        exception_mask_t                exception_mask,
        ipc_port_t                      new_port,
        exception_behavior_t            new_behavior,
        thread_state_flavor_t           new_flavor)
{
        register int    i;
        ipc_port_t      old_port[EXC_TYPES_COUNT];

        if (task == TASK_NULL) {
                return KERN_INVALID_ARGUMENT;
        }

        if (exception_mask & ~EXC_MASK_ALL) {
                return KERN_INVALID_ARGUMENT;
        }

        if (IP_VALID(new_port)) {
                switch (new_behavior) {
                case EXCEPTION_DEFAULT:
                case EXCEPTION_STATE:
                case EXCEPTION_STATE_IDENTITY:
                        break;
                default:
                        return KERN_INVALID_ARGUMENT;
                }
        }
        /* Cannot easily check "new_flavor", but that just means that
         * the flavor in the generated exception message might be garbage:
         * GIGO */

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);
                return KERN_FAILURE;
        }

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                if (exception_mask & (1 << i)) {
                        old_port[i] = task->exc_actions[i].port;
                        task->exc_actions[i].port =
                                ipc_port_copy_send(new_port);
                        task->exc_actions[i].behavior = new_behavior;
                        task->exc_actions[i].flavor = new_flavor;
                } else
                        old_port[i] = IP_NULL;
        }/* for */

        /*
         * Consume send rights without any lock held.
         */
        itk_unlock(task);
        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++)
                if (IP_VALID(old_port[i]))
                        ipc_port_release_send(old_port[i]);
        if (IP_VALID(new_port))          /* consume send right */
                ipc_port_release_send(new_port);

        return KERN_SUCCESS;
}/* task_set_exception_port */

/*
 *      Routine:        thread/task_swap_exception_ports [kernel call]
 *      Purpose:
 *                      Sets the thread/task exception port, flavor and
 *                      behavior for the exception types specified by the
 *                      mask.
 *
 *                      The old ports, behavior and flavors are returned
 *                      Count specifies the array sizes on input and
 *                      the number of returned ports etc. on output.  The
 *                      arrays must be large enough to hold all the returned
 *                      data, MIG returnes an error otherwise.  The masks
 *                      array specifies the corresponding exception type(s).
 *
 *      Conditions:
 *              Nothing locked.  If successful, consumes
 *              the supplied send right.
 *
 *              Returns upto [in} CountCnt elements.
 *      Returns:
 *              KERN_SUCCESS            Changed the special port.
 *              KERN_INVALID_ARGUMENT   The thread is null,
 *                                      Illegal mask bit set.
 *                                      Illegal exception behavior
 *              KERN_FAILURE            The thread is dead.
 */

kern_return_t
thread_swap_exception_ports(
        thread_act_t                    thr_act,
        exception_mask_t                exception_mask,
        ipc_port_t                      new_port,
        exception_behavior_t            new_behavior,
        thread_state_flavor_t           new_flavor,
        exception_mask_array_t          masks,
        mach_msg_type_number_t          * CountCnt,
        exception_port_array_t          ports,
        exception_behavior_array_t      behaviors,
        thread_state_flavor_array_t     flavors )
{
        register int    i,
                        j,
                        count;
        ipc_port_t      old_port[EXC_TYPES_COUNT];

        if (!thr_act)
                return KERN_INVALID_ARGUMENT;

        if (exception_mask & ~EXC_MASK_ALL) {
                return KERN_INVALID_ARGUMENT;
        }

        if (IP_VALID(new_port)) {
                switch (new_behavior) {
                case EXCEPTION_DEFAULT:
                case EXCEPTION_STATE:
                case EXCEPTION_STATE_IDENTITY:
                        break;
                default:
                        return KERN_INVALID_ARGUMENT;
                }
        }
        /* Cannot easily check "new_flavor", but that just means that
         * the flavor in the generated exception message might be garbage:
         * GIGO */

        act_lock(thr_act);
        if (!thr_act->active) {
                act_unlock(thr_act);
                return KERN_FAILURE;
        }

        count = 0;

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                if (exception_mask & (1 << i)) {
                        for (j = 0; j < count; j++) {
/*
 *                              search for an identical entry, if found
 *                              set corresponding mask for this exception.
 */
                                if (thr_act->exc_actions[i].port == ports[j] &&
                                  thr_act->exc_actions[i].behavior ==behaviors[j]
                                  && thr_act->exc_actions[i].flavor ==flavors[j])
                                {
                                        masks[j] |= (1 << i);
                                        break;
                                }
                        }/* for */
                        if (j == count) {
                                masks[j] = (1 << i);
                                ports[j] =
                                ipc_port_copy_send(thr_act->exc_actions[i].port);

                                behaviors[j] = thr_act->exc_actions[i].behavior;
                                flavors[j] = thr_act->exc_actions[i].flavor;
                                count++;
                        }

                        old_port[i] = thr_act->exc_actions[i].port;
                        thr_act->exc_actions[i].port =
                                ipc_port_copy_send(new_port);
                        thr_act->exc_actions[i].behavior = new_behavior;
                        thr_act->exc_actions[i].flavor = new_flavor;
                        if (count > *CountCnt) {
                                break;
                        }
                } else
                        old_port[i] = IP_NULL;
        }/* for */

        /*
         * Consume send rights without any lock held.
         */
        act_unlock(thr_act);
        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++)
                if (IP_VALID(old_port[i]))
                        ipc_port_release_send(old_port[i]);
        if (IP_VALID(new_port))          /* consume send right */
                ipc_port_release_send(new_port);
        *CountCnt = count;
        return KERN_SUCCESS;
}/* thread_swap_exception_ports */

kern_return_t
task_swap_exception_ports(
        task_t                          task,
        exception_mask_t                exception_mask,
        ipc_port_t                      new_port,
        exception_behavior_t            new_behavior,
        thread_state_flavor_t           new_flavor,
        exception_mask_array_t          masks,
        mach_msg_type_number_t          * CountCnt,
        exception_port_array_t          ports,
        exception_behavior_array_t      behaviors,
        thread_state_flavor_array_t     flavors         )
{
        register int    i,
                        j,
                        count;
        ipc_port_t      old_port[EXC_TYPES_COUNT];

        if (task == TASK_NULL)
                return KERN_INVALID_ARGUMENT;

        if (exception_mask & ~EXC_MASK_ALL) {
                return KERN_INVALID_ARGUMENT;
        }

        if (IP_VALID(new_port)) {
                switch (new_behavior) {
                case EXCEPTION_DEFAULT:
                case EXCEPTION_STATE:
                case EXCEPTION_STATE_IDENTITY:
                        break;
                default:
                        return KERN_INVALID_ARGUMENT;
                }
        }
        /* Cannot easily check "new_flavor", but that just means that
         * the flavor in the generated exception message might be garbage:
         * GIGO */

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);
                return KERN_FAILURE;
        }

        count = 0;

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                if (exception_mask & (1 << i)) {
                        for (j = 0; j < count; j++) {
/*
 *                              search for an identical entry, if found
 *                              set corresponding mask for this exception.
 */
                                if (task->exc_actions[i].port == ports[j] &&
                                  task->exc_actions[i].behavior == behaviors[j]
                                  && task->exc_actions[i].flavor == flavors[j])
                                {
                                        masks[j] |= (1 << i);
                                        break;
                                }
                        }/* for */
                        if (j == count) {
                                masks[j] = (1 << i);
                                ports[j] =
                                ipc_port_copy_send(task->exc_actions[i].port);
                                behaviors[j] = task->exc_actions[i].behavior;
                                flavors[j] = task->exc_actions[i].flavor;
                                count++;
                        }
                        old_port[i] = task->exc_actions[i].port;
                        task->exc_actions[i].port =
                                ipc_port_copy_send(new_port);
                        task->exc_actions[i].behavior = new_behavior;
                        task->exc_actions[i].flavor = new_flavor;
                        if (count > *CountCnt) {
                                break;
                        }
                } else
                        old_port[i] = IP_NULL;
        }/* for */


        /*
         * Consume send rights without any lock held.
         */
        itk_unlock(task);
        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++)
                if (IP_VALID(old_port[i]))
                        ipc_port_release_send(old_port[i]);
        if (IP_VALID(new_port))          /* consume send right */
                ipc_port_release_send(new_port);
        *CountCnt = count;

        return KERN_SUCCESS;
}/* task_swap_exception_ports */

/*
 *      Routine:        thread/task_get_exception_ports [kernel call]
 *      Purpose:
 *              Clones a send right for each of the thread/task's exception
 *              ports specified in the mask and returns the behaviour
 *              and flavor of said port.
 *
 *              Returns upto [in} CountCnt elements.
 *
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Extracted a send right.
 *              KERN_INVALID_ARGUMENT   The thread is null,
 *                                      Invalid special port,
 *                                      Illegal mask bit set.
 *              KERN_FAILURE            The thread is dead.
 */

kern_return_t
thread_get_exception_ports(
        thread_act_t                    thr_act,
        exception_mask_t                exception_mask,
        exception_mask_array_t          masks,
        mach_msg_type_number_t          * CountCnt,
        exception_port_array_t          ports,
        exception_behavior_array_t      behaviors,
        thread_state_flavor_array_t     flavors         )
{
        register int    i,
                        j,
                        count;

        if (!thr_act)
                return KERN_INVALID_ARGUMENT;

        if (exception_mask & ~EXC_MASK_ALL) {
                return KERN_INVALID_ARGUMENT;
        }

        act_lock(thr_act);
        if (!thr_act->active) {
                act_unlock(thr_act);
                return KERN_FAILURE;
        }

        count = 0;

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                if (exception_mask & (1 << i)) {
                        for (j = 0; j < count; j++) {
/*
 *                              search for an identical entry, if found
 *                              set corresponding mask for this exception.
 */
                                if (thr_act->exc_actions[i].port == ports[j] &&
                                  thr_act->exc_actions[i].behavior ==behaviors[j]
                                  && thr_act->exc_actions[i].flavor == flavors[j])
                                {
                                        masks[j] |= (1 << i);
                                        break;
                                }
                        }/* for */
                        if (j == count) {
                                masks[j] = (1 << i);
                                ports[j] =
                                ipc_port_copy_send(thr_act->exc_actions[i].port);
                                behaviors[j] = thr_act->exc_actions[i].behavior;
                                flavors[j] = thr_act->exc_actions[i].flavor;
                                count++;
                                if (count >= *CountCnt) {
                                        break;
                                }
                        }
                }
        }/* for */

        act_unlock(thr_act);

        *CountCnt = count;
        return KERN_SUCCESS;
}/* thread_get_exception_ports */

kern_return_t
task_get_exception_ports(
        task_t                          task,
        exception_mask_t                exception_mask,
        exception_mask_array_t          masks,
        mach_msg_type_number_t          * CountCnt,
        exception_port_array_t          ports,
        exception_behavior_array_t      behaviors,
        thread_state_flavor_array_t     flavors         )
{
        register int    i,
                        j,
                        count;

        if (task == TASK_NULL)
                return KERN_INVALID_ARGUMENT;

        if (exception_mask & ~EXC_MASK_ALL) {
                return KERN_INVALID_ARGUMENT;
        }

        itk_lock(task);
        if (task->itk_self == IP_NULL) {
                itk_unlock(task);
                return KERN_FAILURE;
        }

        count = 0;

        for (i = FIRST_EXCEPTION; i < EXC_TYPES_COUNT; i++) {
                if (exception_mask & (1 << i)) {
                        for (j = 0; j < count; j++) {
/*
 *                              search for an identical entry, if found
 *                              set corresponding mask for this exception.
 */
                                if (task->exc_actions[i].port == ports[j] &&
                                  task->exc_actions[i].behavior == behaviors[j]
                                  && task->exc_actions[i].flavor == flavors[j])
                                {
                                        masks[j] |= (1 << i);
                                        break;
                                }
                        }/* for */
                        if (j == count) {
                                masks[j] = (1 << i);
                                ports[j] =
                                  ipc_port_copy_send(task->exc_actions[i].port);
                                behaviors[j] = task->exc_actions[i].behavior;
                                flavors[j] = task->exc_actions[i].flavor;
                                count++;
                                if (count > *CountCnt) {
                                        break;
                                }
                        }
                }
        }/* for */

        itk_unlock(task);

        *CountCnt = count;
        return KERN_SUCCESS;
}/* task_get_exception_ports */