xnu-344.21.73.tar.gz

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

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The 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, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * @OSF_FREE_COPYRIGHT@
 */
/* 
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988 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:   kern/task.c
 *      Author: Avadis Tevanian, Jr., Michael Wayne Young, David Golub,
 *              David Black
 *
 *      Task management primitives implementation.
 */
/*
 * Copyright (c) 1993 The University of Utah and
 * the Computer Systems Laboratory (CSL).  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.
 *
 * THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
 * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSL DISCLAIM ANY LIABILITY OF
 * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * CSL requests users of this software to return to csl-dist@cs.utah.edu any
 * improvements that they make and grant CSL redistribution rights.
 *
 */

#include <mach_kdb.h>
#include <mach_host.h>
#include <mach_prof.h>
#include <fast_tas.h>
#include <task_swapper.h>
#include <platforms.h>

#include <mach/boolean.h>
#include <mach/machine/vm_types.h>
#include <mach/vm_param.h>
#include <mach/semaphore.h>
#include <mach/task_info.h>
#include <mach/task_special_ports.h>
#include <mach/mach_types.h>
#include <ipc/ipc_space.h>
#include <ipc/ipc_entry.h>
#include <kern/mach_param.h>
#include <kern/misc_protos.h>
#include <kern/task.h>
#include <kern/thread.h>
#include <kern/zalloc.h>
#include <kern/kalloc.h>
#include <kern/processor.h>
#include <kern/sched_prim.h>    /* for thread_wakeup */
#include <kern/ipc_tt.h>
#include <kern/ledger.h>
#include <kern/host.h>
#include <vm/vm_kern.h>         /* for kernel_map, ipc_kernel_map */
#include <kern/profile.h>
#include <kern/assert.h>
#include <kern/sync_lock.h>
#if     MACH_KDB
#include <ddb/db_sym.h>
#endif  /* MACH_KDB */

#if     TASK_SWAPPER
#include <kern/task_swap.h>
#endif  /* TASK_SWAPPER */

#ifdef __ppc__
#include <ppc/exception.h>
#include <ppc/hw_perfmon.h>
#endif

/*
 * Exported interfaces
 */

#include <mach/task_server.h>
#include <mach/mach_host_server.h>
#include <mach/host_security_server.h>
#include <vm/task_working_set.h>

task_t  kernel_task;
zone_t  task_zone;

/* Forwards */

void            task_hold_locked(
                        task_t          task);
void            task_wait_locked(
                        task_t          task);
void            task_release_locked(
                        task_t          task);
void            task_collect_scan(void);
void            task_free(
                        task_t          task );
void            task_synchronizer_destroy_all(
                        task_t          task);

kern_return_t   task_set_ledger(
                        task_t          task,
                        ledger_t        wired,
                        ledger_t        paged);

void
task_init(void)
{
        task_zone = zinit(
                        sizeof(struct task),
                        TASK_MAX * sizeof(struct task),
                        TASK_CHUNK * sizeof(struct task),
                        "tasks");

        eml_init();

        /*
         * Create the kernel task as the first task.
         * Task_create_local must assign to kernel_task as a side effect,
         * for other initialization. (:-()
         */
        if (task_create_local(
                        TASK_NULL, FALSE, FALSE, &kernel_task) != KERN_SUCCESS)
                panic("task_init\n");
        vm_map_deallocate(kernel_task->map);
        kernel_task->map = kernel_map;

#if     MACH_ASSERT
        if (watchacts & WA_TASK)
            printf("task_init: kernel_task = %x map=%x\n",
                                kernel_task, kernel_map);
#endif  /* MACH_ASSERT */
}

#if     MACH_HOST

#if 0
static void
task_freeze(
        task_t task)
{
        task_lock(task);
        /*
         *      If may_assign is false, task is already being assigned,
         *      wait for that to finish.
         */
        while (task->may_assign == FALSE) {
                wait_result_t res;

                task->assign_active = TRUE;
                res = thread_sleep_mutex((event_t) &task->assign_active,
                                         &task->lock, THREAD_UNINT);
                assert(res == THREAD_AWAKENED);
        }
        task->may_assign = FALSE;
        task_unlock(task);
        return;
}
#else
#define thread_freeze(thread)   assert(task->processor_set == &default_pset)
#endif

#if 0
static void
task_unfreeze(
        task_t task)
{
        task_lock(task);
        assert(task->may_assign == FALSE);
        task->may_assign = TRUE;
        if (task->assign_active == TRUE) {
                task->assign_active = FALSE;
                thread_wakeup((event_t)&task->assign_active);
        }
        task_unlock(task);
        return;
}
#else
#define thread_unfreeze(thread) assert(task->processor_set == &default_pset)
#endif

#endif  /* MACH_HOST */

/*
 * Create a task running in the kernel address space.  It may
 * have its own map of size mem_size and may have ipc privileges.
 */
kern_return_t
kernel_task_create(
        task_t                  parent_task,
        vm_offset_t             map_base,
        vm_size_t               map_size,
        task_t                  *child_task)
{
        kern_return_t           result;
        task_t                  new_task;
        vm_map_t                old_map;

        /*
         * Create the task.
         */
        result = task_create_local(parent_task, FALSE, TRUE, &new_task);
        if (result != KERN_SUCCESS)
                return (result);

        /*
         * Task_create_local creates the task with a user-space map.
         * We attempt to replace the map and free it afterwards; else
         * task_deallocate will free it (can NOT set map to null before
         * task_deallocate, this impersonates a norma placeholder task).
         * _Mark the memory as pageable_ -- this is what we
         * want for images (like servers) loaded into the kernel.
         */
        if (map_size == 0) {
                vm_map_deallocate(new_task->map);
                new_task->map = kernel_map;
                *child_task = new_task;
        } else {
                old_map = new_task->map;
                if ((result = kmem_suballoc(kernel_map, &map_base,
                                            map_size, TRUE, FALSE,
                                            &new_task->map)) != KERN_SUCCESS) {
                        /*
                         * New task created with ref count of 2 -- decrement by
                         * one to force task deletion.
                         */
                        printf("kmem_suballoc(%x,%x,%x,1,0,&new) Fails\n",
                               kernel_map, map_base, map_size);
                        --new_task->ref_count;
                        task_deallocate(new_task);
                        return (result);
                }
                vm_map_deallocate(old_map);
                *child_task = new_task;
        }
        return (KERN_SUCCESS);
}

kern_return_t
task_create(
        task_t                  parent_task,
        ledger_port_array_t     ledger_ports,
        mach_msg_type_number_t  num_ledger_ports,
        boolean_t               inherit_memory,
        task_t                  *child_task)            /* OUT */
{
        if (parent_task == TASK_NULL)
                return(KERN_INVALID_ARGUMENT);

        return task_create_local(
                        parent_task, inherit_memory, FALSE, child_task);
}

kern_return_t
host_security_create_task_token(
        host_security_t         host_security,
        task_t                  parent_task,
        security_token_t        sec_token,
        host_priv_t             host_priv,
        ledger_port_array_t     ledger_ports,
        mach_msg_type_number_t  num_ledger_ports,
        boolean_t               inherit_memory,
        task_t                  *child_task)            /* OUT */
{
        kern_return_t           result;
        
        if (parent_task == TASK_NULL)
                return(KERN_INVALID_ARGUMENT);

        if (host_security == HOST_NULL)
                return(KERN_INVALID_SECURITY);

        result = task_create_local(
                        parent_task, inherit_memory, FALSE, child_task);

        if (result != KERN_SUCCESS)
                return(result);

        result = host_security_set_task_token(host_security,
                                              *child_task,
                                              sec_token,
                                              host_priv);

        if (result != KERN_SUCCESS)
                return(result);

        return(result);
}

kern_return_t
task_create_local(
        task_t          parent_task,
        boolean_t       inherit_memory,
        boolean_t       kernel_loaded,
        task_t          *child_task)            /* OUT */
{
        task_t          new_task;
        processor_set_t pset;

        new_task = (task_t) zalloc(task_zone);

        if (new_task == TASK_NULL)
                return(KERN_RESOURCE_SHORTAGE);

        /* one ref for just being alive; one for our caller */
        new_task->ref_count = 2;

        if (inherit_memory)
                new_task->map = vm_map_fork(parent_task->map);
        else
                new_task->map = vm_map_create(pmap_create(0),
                                        round_page_32(VM_MIN_ADDRESS),
                                        trunc_page_32(VM_MAX_ADDRESS), TRUE);

        mutex_init(&new_task->lock, ETAP_THREAD_TASK_NEW);
        queue_init(&new_task->thr_acts);
        new_task->suspend_count = 0;
        new_task->thr_act_count = 0;
        new_task->res_act_count = 0;
        new_task->active_act_count = 0;
        new_task->user_stop_count = 0;
        new_task->role = TASK_UNSPECIFIED;
        new_task->active = TRUE;
        new_task->kernel_loaded = kernel_loaded;
        new_task->user_data = 0;
        new_task->faults = 0;
        new_task->cow_faults = 0;
        new_task->pageins = 0;
        new_task->messages_sent = 0;
        new_task->messages_received = 0;
        new_task->syscalls_mach = 0;
        new_task->syscalls_unix=0;
        new_task->csw=0;
        new_task->taskFeatures[0] = 0;                          /* Init task features */
        new_task->taskFeatures[1] = 0;                          /* Init task features */
        new_task->dynamic_working_set = 0;
        
        task_working_set_create(new_task, TWS_SMALL_HASH_LINE_COUNT, 
                                                0, TWS_HASH_STYLE_DEFAULT);

#ifdef MACH_BSD
        new_task->bsd_info = 0;
#endif /* MACH_BSD */

#ifdef __ppc__
        if(per_proc_info[0].pf.Available & pf64Bit) new_task->taskFeatures[0] |= tf64BitData;   /* If 64-bit machine, show we have 64-bit registers at least */
#endif

#if     TASK_SWAPPER
        new_task->swap_state = TASK_SW_IN;
        new_task->swap_flags = 0;
        new_task->swap_ast_waiting = 0;
        new_task->swap_stamp = sched_tick;
        new_task->swap_rss = 0;
        new_task->swap_nswap = 0;
#endif  /* TASK_SWAPPER */

        queue_init(&new_task->semaphore_list);
        queue_init(&new_task->lock_set_list);
        new_task->semaphores_owned = 0;
        new_task->lock_sets_owned = 0;

#if     MACH_HOST
        new_task->may_assign = TRUE;
        new_task->assign_active = FALSE;
#endif  /* MACH_HOST */
        eml_task_reference(new_task, parent_task);

        ipc_task_init(new_task, parent_task);

        new_task->total_user_time.seconds = 0;
        new_task->total_user_time.microseconds = 0;
        new_task->total_system_time.seconds = 0;
        new_task->total_system_time.microseconds = 0;

        task_prof_init(new_task);

        if (parent_task != TASK_NULL) {
#if     MACH_HOST
                /*
                 * Freeze the parent, so that parent_task->processor_set
                 * cannot change.
                 */
                task_freeze(parent_task);
#endif  /* MACH_HOST */
                pset = parent_task->processor_set;
                if (!pset->active)
                        pset = &default_pset;

                new_task->sec_token = parent_task->sec_token;

                shared_region_mapping_ref(parent_task->system_shared_region);
                new_task->system_shared_region = parent_task->system_shared_region;

                new_task->wired_ledger_port = ledger_copy(
                        convert_port_to_ledger(parent_task->wired_ledger_port));
                new_task->paged_ledger_port = ledger_copy(
                        convert_port_to_ledger(parent_task->paged_ledger_port));
        }
        else {
                pset = &default_pset;

                new_task->sec_token = KERNEL_SECURITY_TOKEN;
                new_task->wired_ledger_port = ledger_copy(root_wired_ledger);
                new_task->paged_ledger_port = ledger_copy(root_paged_ledger);
        }

        if (kernel_task == TASK_NULL) {
                new_task->priority = MINPRI_KERNEL;
                new_task->max_priority = MAXPRI_KERNEL;
        }
        else {
                new_task->priority = BASEPRI_DEFAULT;
                new_task->max_priority = MAXPRI_USER;
        }

        pset_lock(pset);
        pset_add_task(pset, new_task);
        pset_unlock(pset);
#if     MACH_HOST
        if (parent_task != TASK_NULL)
                task_unfreeze(parent_task);
#endif  /* MACH_HOST */

#if     FAST_TAS
        if (inherit_memory) {
                new_task->fast_tas_base = parent_task->fast_tas_base;
                new_task->fast_tas_end  = parent_task->fast_tas_end;
        } else {
                new_task->fast_tas_base = (vm_offset_t)0;
                new_task->fast_tas_end  = (vm_offset_t)0;
        }
#endif  /* FAST_TAS */

        ipc_task_enable(new_task);

#if     TASK_SWAPPER
        task_swapout_eligible(new_task);
#endif  /* TASK_SWAPPER */

#if     MACH_ASSERT
        if (watchacts & WA_TASK)
            printf("*** task_create_local(par=%x inh=%x) == 0x%x\n",
                        parent_task, inherit_memory, new_task);
#endif  /* MACH_ASSERT */

        *child_task = new_task;
        return(KERN_SUCCESS);
}

/*
 *      task_deallocate
 *
 *      Drop a reference on a task
 *      Task is locked.
 */
void
task_deallocate(
        task_t          task)
{
        processor_set_t pset;
        int refs;

        if (task == TASK_NULL)
            return;

        task_lock(task);
        refs = --task->ref_count;
        task_unlock(task);

        if (refs > 0)
                return;

#if     TASK_SWAPPER
        /* task_terminate guarantees that this task is off the list */
        assert((task->swap_state & TASK_SW_ELIGIBLE) == 0);
#endif  /* TASK_SWAPPER */

        if(task->dynamic_working_set)
                tws_hash_destroy((tws_hash_t)task->dynamic_working_set);


        eml_task_deallocate(task);

        ipc_task_terminate(task);

#if MACH_HOST
        task_freeze(task);
#endif

        pset = task->processor_set;
        pset_lock(pset);
        pset_remove_task(pset,task);
        pset_unlock(pset);
        pset_deallocate(pset);

#if MACH_HOST
        task_unfreeze(task);
#endif

        if (task->kernel_loaded)
            vm_map_remove(kernel_map, task->map->min_offset,
                          task->map->max_offset, VM_MAP_NO_FLAGS);
        vm_map_deallocate(task->map);
        is_release(task->itk_space);
        task_prof_deallocate(task);
        zfree(task_zone, (vm_offset_t) task);
}


void
task_reference(
        task_t          task)
{
        if (task != TASK_NULL) {
                task_lock(task);
                task->ref_count++;
                task_unlock(task);
        }
}

boolean_t
task_reference_try(
        task_t          task)
{
        if (task != TASK_NULL) {
                if (task_lock_try(task)) {
                        task->ref_count++;
                        task_unlock(task);
                        return TRUE;
                }
        }
        return FALSE;
}

/*
 *      task_terminate:
 *
 *      Terminate the specified task.  See comments on thread_terminate
 *      (kern/thread.c) about problems with terminating the "current task."
 */

kern_return_t
task_terminate(
        task_t          task)
{
        if (task == TASK_NULL)
                return(KERN_INVALID_ARGUMENT);
        if (task->bsd_info)
                return(KERN_FAILURE);
        return (task_terminate_internal(task));
}

kern_return_t
task_terminate_internal(
        task_t          task)
{
        thread_act_t    thr_act, cur_thr_act;
        task_t          cur_task;
        boolean_t       interrupt_save;

        assert(task != kernel_task);

        cur_thr_act = current_act();
        cur_task = cur_thr_act->task;

#if     TASK_SWAPPER
        /*
         *      If task is not resident (swapped out, or being swapped
         *      out), we want to bring it back in (this can block).
         *      NOTE: The only way that this can happen in the current
         *      system is if the task is swapped while it has a thread
         *      in exit(), and the thread does not hit a clean point
         *      to swap itself before getting here.  
         *      Terminating other tasks is another way to this code, but
         *      it is not yet fully supported.
         *      The task_swapin is unconditional.  It used to be done
         *      only if the task is not resident.  Swapping in a
         *      resident task will prevent it from being swapped out 
         *      while it terminates.
         */
        task_swapin(task, TRUE);        /* TRUE means make it unswappable */
#endif  /* TASK_SWAPPER */

        /*
         *      Get the task locked and make sure that we are not racing
         *      with someone else trying to terminate us.
         */
        if (task == cur_task) {
                task_lock(task);
        } else if (task < cur_task) {
                task_lock(task);
                task_lock(cur_task);
        } else {
                task_lock(cur_task);
                task_lock(task);
        }

        if (!task->active || !cur_thr_act->active) {
                /*
                 *      Task or current act is already being terminated.
                 *      Just return an error. If we are dying, this will
                 *      just get us to our AST special handler and that
                 *      will get us to finalize the termination of ourselves.
                 */
                task_unlock(task);
                if (cur_task != task)
                        task_unlock(cur_task);
                return(KERN_FAILURE);
        }
        if (cur_task != task)
                task_unlock(cur_task);

        /*
         * Make sure the current thread does not get aborted out of
         * the waits inside these operations.
         */
        interrupt_save = thread_interrupt_level(THREAD_UNINT);

        /*
         *      Indicate that we want all the threads to stop executing
         *      at user space by holding the task (we would have held
         *      each thread independently in thread_terminate_internal -
         *      but this way we may be more likely to already find it
         *      held there).  Mark the task inactive, and prevent
         *      further task operations via the task port.
         */
        task_hold_locked(task);
        task->active = FALSE;
        ipc_task_disable(task);

        /*
         *      Terminate each activation in the task.
         *
         *      Each terminated activation will run it's special handler
         *      when its current kernel context is unwound.  That will
         *      clean up most of the thread resources.  Then it will be
         *      handed over to the reaper, who will finally remove the
         *      thread from the task list and free the structures.
         */
        queue_iterate(&task->thr_acts, thr_act, thread_act_t, thr_acts) {
                        thread_terminate_internal(thr_act);
        }

        /*
         *      Clean up any virtual machine state/resources associated
         *      with the current activation because it may hold wiring
         *      and other references on resources we will be trying to
         *      release below.
         */
        if (cur_thr_act->task == task)
                act_virtual_machine_destroy(cur_thr_act);

        task_unlock(task);

        /*
         *      Destroy all synchronizers owned by the task.
         */
        task_synchronizer_destroy_all(task);

        /*
         *      Destroy the IPC space, leaving just a reference for it.
         */
        if (!task->kernel_loaded)
                ipc_space_destroy(task->itk_space);

        /*
         * If the current thread is a member of the task
         * being terminated, then the last reference to
         * the task will not be dropped until the thread
         * is finally reaped.  To avoid incurring the
         * expense of removing the address space regions
         * at reap time, we do it explictly here.
         */
        (void) vm_map_remove(task->map,
                             task->map->min_offset,
                             task->map->max_offset, VM_MAP_NO_FLAGS);

        shared_region_mapping_dealloc(task->system_shared_region);

        /*
         * Flush working set here to avoid I/O in reaper thread
         */
        if(task->dynamic_working_set)
                tws_hash_ws_flush((tws_hash_t)
                                task->dynamic_working_set);

        /*
         * We no longer need to guard against being aborted, so restore
         * the previous interruptible state.
         */
        thread_interrupt_level(interrupt_save);

#if __ppc__
    perfmon_release_facility(task); // notify the perfmon facility
#endif

        /*
         * Get rid of the task active reference on itself.
         */
        task_deallocate(task);

        return(KERN_SUCCESS);
}

/*
 * task_halt -  Shut the current task down (except for the current thread) in
 *              preparation for dramatic changes to the task (probably exec).
 *              We hold the task, terminate all other threads in the task and
 *              wait for them to terminate, clean up the portspace, and when
 *              all done, let the current thread go.
 */
kern_return_t
task_halt(
        task_t          task)
{
        thread_act_t    thr_act, cur_thr_act;
        task_t          cur_task;

        assert(task != kernel_task);

        cur_thr_act = current_act();
        cur_task = cur_thr_act->task;

        if (task != cur_task) {
                return(KERN_INVALID_ARGUMENT);
        }

#if     TASK_SWAPPER
        /*
         *      If task is not resident (swapped out, or being swapped
         *      out), we want to bring it back in and make it unswappable.
         *      This can block, so do it early.
         */
        task_swapin(task, TRUE);        /* TRUE means make it unswappable */
#endif  /* TASK_SWAPPER */

        task_lock(task);

        if (!task->active || !cur_thr_act->active) {
                /*
                 *      Task or current thread is already being terminated.
                 *      Hurry up and return out of the current kernel context
                 *      so that we run our AST special handler to terminate
                 *      ourselves.
                 */
                task_unlock(task);
                return(KERN_FAILURE);
        }

        if (task->thr_act_count > 1) {
                /*
                 * Mark all the threads to keep them from starting any more
                 * user-level execution.  The thread_terminate_internal code
                 * would do this on a thread by thread basis anyway, but this
                 * gives us a better chance of not having to wait there.
                 */
                task_hold_locked(task);

                /*
                 *      Terminate all the other activations in the task.
                 *
                 *      Each terminated activation will run it's special handler
                 *      when its current kernel context is unwound.  That will
                 *      clean up most of the thread resources.  Then it will be
                 *      handed over to the reaper, who will finally remove the
                 *      thread from the task list and free the structures.
                 */
                queue_iterate(&task->thr_acts, thr_act, thread_act_t,thr_acts) {
                        if (thr_act != cur_thr_act)
                                thread_terminate_internal(thr_act);
                }
                task_release_locked(task);
        }

        /*
         *      If the current thread has any virtual machine state
         *      associated with it, we need to explicitly clean that
         *      up now (because we did not terminate the current act)
         *      before we try to clean up the task VM and port spaces.
         */
        act_virtual_machine_destroy(cur_thr_act);

        task_unlock(task);

        /*
         *      Destroy all synchronizers owned by the task.
         */
        task_synchronizer_destroy_all(task);

        /*
         *      Destroy the contents of the IPC space, leaving just
         *      a reference for it.
         */
        if (!task->kernel_loaded)
                ipc_space_clean(task->itk_space);

        /*
         * Clean out the address space, as we are going to be
         * getting a new one.
         */
        (void) vm_map_remove(task->map,
                             task->map->min_offset,
                             task->map->max_offset, VM_MAP_NO_FLAGS);

        return KERN_SUCCESS;
}

/*
 *      task_hold_locked:
 *
 *      Suspend execution of the specified task.
 *      This is a recursive-style suspension of the task, a count of
 *      suspends is maintained.
 *
 *      CONDITIONS: the task is locked and active.
 */
void
task_hold_locked(
        register task_t task)
{
        register thread_act_t   thr_act;

        assert(task->active);

        if (task->suspend_count++ > 0)
                return;

        /*
         *      Iterate through all the thread_act's and hold them.
         */
        queue_iterate(&task->thr_acts, thr_act, thread_act_t, thr_acts) {
                act_lock_thread(thr_act);
                thread_hold(thr_act);
                act_unlock_thread(thr_act);
        }
}

/*
 *      task_hold:
 *
 *      Same as the internal routine above, except that is must lock
 *      and verify that the task is active.  This differs from task_suspend
 *      in that it places a kernel hold on the task rather than just a 
 *      user-level hold.  This keeps users from over resuming and setting
 *      it running out from under the kernel.
 *
 *      CONDITIONS: the caller holds a reference on the task
 */
kern_return_t
task_hold(task_t task)
{
        kern_return_t kret;
        
        if (task == TASK_NULL)
                return (KERN_INVALID_ARGUMENT);
        task_lock(task);
        if (!task->active) {
                task_unlock(task);
                return (KERN_FAILURE);
        }
        task_hold_locked(task);
        task_unlock(task);

        return(KERN_SUCCESS);
}

/*
 * Routine:     task_wait_locked
 *      Wait for all threads in task to stop.
 *
 * Conditions:
 *      Called with task locked, active, and held.
 */
void
task_wait_locked(
        register task_t         task)
{
        register thread_act_t   thr_act, cur_thr_act;

        assert(task->active);
        assert(task->suspend_count > 0);

        cur_thr_act = current_act();
        /*
         *      Iterate through all the thread's and wait for them to
         *      stop.  Do not wait for the current thread if it is within
         *      the task.
         */
        queue_iterate(&task->thr_acts, thr_act, thread_act_t, thr_acts) {
                if (thr_act != cur_thr_act) {
                        thread_shuttle_t thr_shuttle;

                        thr_shuttle = act_lock_thread(thr_act);
                        thread_wait(thr_shuttle);
                        act_unlock_thread(thr_act);
                }
        }
}

/*
 *      task_release_locked:
 *
 *      Release a kernel hold on a task.
 *
 *      CONDITIONS: the task is locked and active
 */
void
task_release_locked(
        register task_t task)
{
        register thread_act_t   thr_act;

        assert(task->active);
        assert(task->suspend_count > 0);

        if (--task->suspend_count > 0)
                return;

        /*
         *      Iterate through all the thread_act's and hold them.
         *      Do not hold the current thread_act if it is within the
         *      task.
         */
        queue_iterate(&task->thr_acts, thr_act, thread_act_t, thr_acts) {
                act_lock_thread(thr_act);
                thread_release(thr_act);
                act_unlock_thread(thr_act);
        }
}

/*
 *      task_release:
 *
 *      Same as the internal routine above, except that it must lock
 *      and verify that the task is active.
 *
 *      CONDITIONS: The caller holds a reference to the task
 */
kern_return_t
task_release(task_t task)
{
        kern_return_t kret;
        
        if (task == TASK_NULL)
                return (KERN_INVALID_ARGUMENT);
        task_lock(task);
        if (!task->active) {
                task_unlock(task);
                return (KERN_FAILURE);
        }
        task_release_locked(task);
        task_unlock(task);

        return(KERN_SUCCESS);
}

kern_return_t
task_threads(
        task_t                  task,
        thread_act_array_t      *thr_act_list,
        mach_msg_type_number_t  *count)
{
        unsigned int            actual; /* this many thr_acts */
        thread_act_t            thr_act;
        thread_act_t            *thr_acts;
        thread_t                thread;
        int                     i, j;

        vm_size_t size, size_needed;
        vm_offset_t addr;

        if (task == TASK_NULL)
                return KERN_INVALID_ARGUMENT;

        size = 0; addr = 0;

        for (;;) {
                task_lock(task);
                if (!task->active) {
                        task_unlock(task);
                        if (size != 0)
                                kfree(addr, size);
                        return KERN_FAILURE;
                }

                actual = task->thr_act_count;

                /* do we have the memory we need? */
                size_needed = actual * sizeof(mach_port_t);
                if (size_needed <= size)
                        break;

                /* unlock the task and allocate more memory */
                task_unlock(task);

                if (size != 0)
                        kfree(addr, size);

                assert(size_needed > 0);
                size = size_needed;

                addr = kalloc(size);
                if (addr == 0)
                        return KERN_RESOURCE_SHORTAGE;
        }

        /* OK, have memory and the task is locked & active */
        thr_acts = (thread_act_t *) addr;

        for (i = j = 0, thr_act = (thread_act_t) queue_first(&task->thr_acts);
             i < actual;
             i++, thr_act = (thread_act_t) queue_next(&thr_act->thr_acts)) {
                act_lock(thr_act);
                if (thr_act->ref_count > 0) {
                        act_locked_act_reference(thr_act);
                        thr_acts[j++] = thr_act;
                }
                act_unlock(thr_act);
        }
        assert(queue_end(&task->thr_acts, (queue_entry_t) thr_act));

        actual = j;
        size_needed = actual * sizeof(mach_port_t);

        /* can unlock task now that we've got the thr_act refs */
        task_unlock(task);

        if (actual == 0) {
                /* no thr_acts, so return null pointer and deallocate memory */

                *thr_act_list = 0;
                *count = 0;

                if (size != 0)
                        kfree(addr, size);
        } else {
                /* if we allocated too much, must copy */

                if (size_needed < size) {
                        vm_offset_t newaddr;

                        newaddr = kalloc(size_needed);
                        if (newaddr == 0) {
                                for (i = 0; i < actual; i++)
                                        act_deallocate(thr_acts[i]);
                                kfree(addr, size);
                                return KERN_RESOURCE_SHORTAGE;
                        }

                        bcopy((char *) addr, (char *) newaddr, size_needed);
                        kfree(addr, size);
                        thr_acts = (thread_act_t *) newaddr;
                }

                *thr_act_list = thr_acts;
                *count = actual;

                /* do the conversion that Mig should handle */

                for (i = 0; i < actual; i++)
                        ((ipc_port_t *) thr_acts)[i] =
                                convert_act_to_port(thr_acts[i]);
        }

        return KERN_SUCCESS;
}

/*
 * Routine:     task_suspend
 *      Implement a user-level suspension on a task.
 *
 * Conditions:
 *      The caller holds a reference to the task
 */
kern_return_t
task_suspend(
        register task_t         task)
{
        if (task == TASK_NULL)
                return (KERN_INVALID_ARGUMENT);

        task_lock(task);
        if (!task->active) {
                task_unlock(task);
                return (KERN_FAILURE);
        }
        if ((task->user_stop_count)++ > 0) {
                /*
                 *      If the stop count was positive, the task is
                 *      already stopped and we can exit.
                 */
                task_unlock(task);
                return (KERN_SUCCESS);
        }

        /*
         * Put a kernel-level hold on the threads in the task (all
         * user-level task suspensions added together represent a
         * single kernel-level hold).  We then wait for the threads
         * to stop executing user code.
         */
        task_hold_locked(task);
        task_wait_locked(task);
        task_unlock(task);
        return (KERN_SUCCESS);
}

/*
 * Routine:     task_resume
 *              Release a kernel hold on a task.
 *              
 * Conditions:
 *              The caller holds a reference to the task
 */
kern_return_t 
task_resume(register task_t task)
{
        register boolean_t      release;

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

        release = FALSE;
        task_lock(task);
        if (!task->active) {
                task_unlock(task);
                return(KERN_FAILURE);
        }
        if (task->user_stop_count > 0) {
                if (--(task->user_stop_count) == 0)
                        release = TRUE;
        }
        else {
                task_unlock(task);
                return(KERN_FAILURE);
        }

        /*
         *      Release the task if necessary.
         */
        if (release)
                task_release_locked(task);

        task_unlock(task);
        return(KERN_SUCCESS);
}

kern_return_t
host_security_set_task_token(
        host_security_t  host_security,
        task_t           task,
        security_token_t sec_token,
        host_priv_t      host_priv)
{
        kern_return_t    kr;

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

        if (host_security == HOST_NULL)
                return(KERN_INVALID_SECURITY);

        task_lock(task);
        task->sec_token = sec_token;
        task_unlock(task);

        if (host_priv != HOST_PRIV_NULL) {
                kr = task_set_special_port(task,
                                TASK_HOST_PORT,
                                ipc_port_make_send(realhost.host_priv_self));
        } else {
                kr = task_set_special_port(task,
                                TASK_HOST_PORT,
                                ipc_port_make_send(realhost.host_self));
        }
        return(kr);
}

/*
 * Utility routine to set a ledger
 */
kern_return_t
task_set_ledger(
        task_t          task,
        ledger_t        wired,
        ledger_t        paged)
{
        if (task == TASK_NULL)
                return(KERN_INVALID_ARGUMENT);

        task_lock(task);
        if (wired) {
                ipc_port_release_send(task->wired_ledger_port);
                task->wired_ledger_port = ledger_copy(wired);
        }                
        if (paged) {
                ipc_port_release_send(task->paged_ledger_port);
                task->paged_ledger_port = ledger_copy(paged);
        }                
        task_unlock(task);

        return(KERN_SUCCESS);
}

/*
 * This routine was added, pretty much exclusively, for registering the
 * RPC glue vector for in-kernel short circuited tasks.  Rather than
 * removing it completely, I have only disabled that feature (which was
 * the only feature at the time).  It just appears that we are going to
 * want to add some user data to tasks in the future (i.e. bsd info,
 * task names, etc...), so I left it in the formal task interface.
 */
kern_return_t
task_set_info(
        task_t          task,
        task_flavor_t   flavor,
        task_info_t     task_info_in,           /* pointer to IN array */
        mach_msg_type_number_t  task_info_count)
{
        vm_map_t                map;

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

        switch (flavor) {
            default:
                return (KERN_INVALID_ARGUMENT);
        }
        return (KERN_SUCCESS);
}

kern_return_t
task_info(
        task_t                  task,
        task_flavor_t           flavor,
        task_info_t             task_info_out,
        mach_msg_type_number_t  *task_info_count)
{
        thread_t        thread;
        vm_map_t        map;

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

        switch (flavor) {

            case TASK_BASIC_INFO:
            {
                register task_basic_info_t      basic_info;

                if (*task_info_count < TASK_BASIC_INFO_COUNT) {
                    return(KERN_INVALID_ARGUMENT);
                }

                basic_info = (task_basic_info_t) task_info_out;

                map = (task == kernel_task) ? kernel_map : task->map;

                basic_info->virtual_size  = map->size;
                basic_info->resident_size = pmap_resident_count(map->pmap)
                                                   * PAGE_SIZE;

                task_lock(task);
                basic_info->policy = ((task != kernel_task)?
                                                                                  POLICY_TIMESHARE: POLICY_RR);
                basic_info->suspend_count = task->user_stop_count;
                basic_info->user_time.seconds
                                = task->total_user_time.seconds;
                basic_info->user_time.microseconds
                                = task->total_user_time.microseconds;
                basic_info->system_time.seconds
                                = task->total_system_time.seconds;
                basic_info->system_time.microseconds 
                                = task->total_system_time.microseconds;
                task_unlock(task);

                *task_info_count = TASK_BASIC_INFO_COUNT;
                break;
            }

            case TASK_THREAD_TIMES_INFO:
            {
                register task_thread_times_info_t times_info;
                register thread_t       thread;
                register thread_act_t   thr_act;

                if (*task_info_count < TASK_THREAD_TIMES_INFO_COUNT) {
                    return (KERN_INVALID_ARGUMENT);
                }

                times_info = (task_thread_times_info_t) task_info_out;
                times_info->user_time.seconds = 0;
                times_info->user_time.microseconds = 0;
                times_info->system_time.seconds = 0;
                times_info->system_time.microseconds = 0;

                task_lock(task);
                queue_iterate(&task->thr_acts, thr_act,
                              thread_act_t, thr_acts)
                {
                    time_value_t user_time, system_time;
                    spl_t        s;

                    thread = act_lock_thread(thr_act);

                    /* JMM - add logic to skip threads that have migrated
                     * into this task?
                     */

                    assert(thread);  /* Must have thread */
                    s = splsched();
                    thread_lock(thread);

                    thread_read_times(thread, &user_time, &system_time);

                    thread_unlock(thread);
                    splx(s);
                    act_unlock_thread(thr_act);

                    time_value_add(&times_info->user_time, &user_time);
                    time_value_add(&times_info->system_time, &system_time);
                }
                task_unlock(task);

                *task_info_count = TASK_THREAD_TIMES_INFO_COUNT;
                break;
            }

            case TASK_SCHED_FIFO_INFO:
            {

                if (*task_info_count < POLICY_FIFO_BASE_COUNT)
                        return(KERN_INVALID_ARGUMENT);

                return(KERN_INVALID_POLICY);
            }

            case TASK_SCHED_RR_INFO:
            {
                register policy_rr_base_t       rr_base;

                if (*task_info_count < POLICY_RR_BASE_COUNT)
                        return(KERN_INVALID_ARGUMENT);

                rr_base = (policy_rr_base_t) task_info_out;

                task_lock(task);
                if (task != kernel_task) {
                        task_unlock(task);
                        return(KERN_INVALID_POLICY);
                }

                rr_base->base_priority = task->priority;
                task_unlock(task);

                rr_base->quantum = tick / 1000;

                *task_info_count = POLICY_RR_BASE_COUNT;
                break;
            }

            case TASK_SCHED_TIMESHARE_INFO:
            {
                register policy_timeshare_base_t        ts_base;

                if (*task_info_count < POLICY_TIMESHARE_BASE_COUNT)
                        return(KERN_INVALID_ARGUMENT);

                ts_base = (policy_timeshare_base_t) task_info_out;

                task_lock(task);
                if (task == kernel_task) {
                        task_unlock(task);
                        return(KERN_INVALID_POLICY);
                }

                ts_base->base_priority = task->priority;
                task_unlock(task);

                *task_info_count = POLICY_TIMESHARE_BASE_COUNT;
                break;
            }

            case TASK_SECURITY_TOKEN:
            {
                register security_token_t       *sec_token_p;

                if (*task_info_count < TASK_SECURITY_TOKEN_COUNT) {
                    return(KERN_INVALID_ARGUMENT);
                }

                sec_token_p = (security_token_t *) task_info_out;

                task_lock(task);
                *sec_token_p = task->sec_token;
                task_unlock(task);

                *task_info_count = TASK_SECURITY_TOKEN_COUNT;
                break;
            }
            
            case TASK_SCHED_INFO:
                        return(KERN_INVALID_ARGUMENT);

            case TASK_EVENTS_INFO:
            {
                register task_events_info_t     events_info;

                if (*task_info_count < TASK_EVENTS_INFO_COUNT) {
                    return(KERN_INVALID_ARGUMENT);
                }

                events_info = (task_events_info_t) task_info_out;

                task_lock(task);
                events_info->faults = task->faults;
                events_info->pageins = task->pageins;
                events_info->cow_faults = task->cow_faults;
                events_info->messages_sent = task->messages_sent;
                events_info->messages_received = task->messages_received;
                events_info->syscalls_mach = task->syscalls_mach;
                events_info->syscalls_unix = task->syscalls_unix;
                events_info->csw = task->csw;
                task_unlock(task);

                *task_info_count = TASK_EVENTS_INFO_COUNT;
                break;
            }

            default:
                return (KERN_INVALID_ARGUMENT);
        }

        return(KERN_SUCCESS);
}

/*
 *      task_assign:
 *
 *      Change the assigned processor set for the task
 */
kern_return_t
task_assign(
        task_t          task,
        processor_set_t new_pset,
        boolean_t       assign_threads)
{
#ifdef  lint
        task++; new_pset++; assign_threads++;
#endif  /* lint */
        return(KERN_FAILURE);
}

/*
 *      task_assign_default:
 *
 *      Version of task_assign to assign to default processor set.
 */
kern_return_t
task_assign_default(
        task_t          task,
        boolean_t       assign_threads)
{
    return (task_assign(task, &default_pset, assign_threads));
}

/*
 *      task_get_assignment
 *
 *      Return name of processor set that task is assigned to.
 */
kern_return_t
task_get_assignment(
        task_t          task,
        processor_set_t *pset)
{
        if (!task->active)
                return(KERN_FAILURE);

        *pset = task->processor_set;
        pset_reference(*pset);
        return(KERN_SUCCESS);
}


/*
 *      task_policy
 *
 *      Set scheduling policy and parameters, both base and limit, for
 *      the given task. Policy must be a policy which is enabled for the
 *      processor set. Change contained threads if requested. 
 */
kern_return_t
task_policy(
        task_t                                  task,
        policy_t                                policy_id,
        policy_base_t                   base,
        mach_msg_type_number_t  count,
        boolean_t                               set_limit,
        boolean_t                               change)
{
        return(KERN_FAILURE);
}

/*
 *      task_set_policy
 *
 *      Set scheduling policy and parameters, both base and limit, for 
 *      the given task. Policy can be any policy implemented by the
 *      processor set, whether enabled or not. Change contained threads
 *      if requested.
 */
kern_return_t
task_set_policy(
        task_t                                  task,
        processor_set_t                 pset,
        policy_t                                policy_id,
        policy_base_t                   base,
        mach_msg_type_number_t  base_count,
        policy_limit_t                  limit,
        mach_msg_type_number_t  limit_count,
        boolean_t                               change)
{
        return(KERN_FAILURE);
}

/*
 *      task_collect_scan:
 *
 *      Attempt to free resources owned by tasks.
 */

void
task_collect_scan(void)
{
        register task_t         task, prev_task;
        processor_set_t         pset = &default_pset;

        pset_lock(pset);
        pset->ref_count++;
        task = (task_t) queue_first(&pset->tasks);
        while (!queue_end(&pset->tasks, (queue_entry_t) task)) {
                task_lock(task);
                if (task->ref_count > 0) {

                        task_reference_locked(task);
                        task_unlock(task);

#if MACH_HOST
                        /*
                         *      While we still have the pset locked, freeze the task in
                         *      this pset.  That way, when we get back from collecting
                         *      it, we can dereference the pset_tasks chain for the task
                         *      and be assured that we are still in this chain.
                         */
                        task_freeze(task);
#endif

                        pset_unlock(pset);

                        pmap_collect(task->map->pmap);

                        pset_lock(pset);
                        prev_task = task;
                        task = (task_t) queue_next(&task->pset_tasks);

#if MACH_HOST
                        task_unfreeze(prev_task);
#endif

                        task_deallocate(prev_task);
                } else {
                        task_unlock(task);
                        task = (task_t) queue_next(&task->pset_tasks);
                }
        }

        pset_unlock(pset);

        pset_deallocate(pset);
}

/* Also disabled in vm/vm_pageout.c */
boolean_t task_collect_allowed = FALSE;
unsigned task_collect_last_tick = 0;
unsigned task_collect_max_rate = 0;             /* in ticks */

/*
 *      consider_task_collect:
 *
 *      Called by the pageout daemon when the system needs more free pages.
 */

void
consider_task_collect(void)
{
        /*
         *      By default, don't attempt task collection more frequently
         *      than once per second.
         */

        if (task_collect_max_rate == 0)
                task_collect_max_rate = (1 << SCHED_TICK_SHIFT) + 1;

        if (task_collect_allowed &&
            (sched_tick > (task_collect_last_tick + task_collect_max_rate))) {
                task_collect_last_tick = sched_tick;
                task_collect_scan();
        }
}

kern_return_t
task_set_ras_pc(
        task_t          task,
        vm_offset_t     pc,
        vm_offset_t     endpc)
{
#if     FAST_TAS
        extern int fast_tas_debug;
 
        if (fast_tas_debug) {
                printf("task 0x%x: setting fast_tas to [0x%x, 0x%x]\n",
                       task, pc, endpc);
        }
        task_lock(task);
        task->fast_tas_base = pc;
        task->fast_tas_end =  endpc;
        task_unlock(task);
        return KERN_SUCCESS;
 
#else   /* FAST_TAS */
#ifdef  lint
        task++;
        pc++;
        endpc++;
#endif  /* lint */
 
        return KERN_FAILURE;
 
#endif  /* FAST_TAS */
}

void
task_synchronizer_destroy_all(task_t task)
{
        semaphore_t     semaphore;
        lock_set_t      lock_set;

        /*
         *  Destroy owned semaphores
         */

        while (!queue_empty(&task->semaphore_list)) {
                semaphore = (semaphore_t) queue_first(&task->semaphore_list);
                (void) semaphore_destroy(task, semaphore);
        }

        /*
         *  Destroy owned lock sets
         */

        while (!queue_empty(&task->lock_set_list)) {
                lock_set = (lock_set_t) queue_first(&task->lock_set_list);
                (void) lock_set_destroy(task, lock_set);
        }
}

/*
 *      task_set_port_space:
 *
 *      Set port name space of task to specified size.
 */

kern_return_t
task_set_port_space(
        task_t          task,
        int             table_entries)
{
        kern_return_t kr;
        
        is_write_lock(task->itk_space);
        kr = ipc_entry_grow_table(task->itk_space, table_entries);
        if (kr == KERN_SUCCESS)
                is_write_unlock(task->itk_space);
        return kr;
}

/*
 * We need to export some functions to other components that
 * are currently implemented in macros within the osfmk
 * component.  Just export them as functions of the same name.
 */
boolean_t is_kerneltask(task_t t)
{
        if (t == kernel_task)
                return(TRUE);
        else
                return((t->kernel_loaded));
}

#undef current_task
task_t current_task()
{
        return (current_task_fast());
}