xnu-792.6.56.tar.gz

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

/*
 * Copyright (c) 2000-2005 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * 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 <platforms.h>

#include <mach/mach_types.h>
#include <mach/boolean.h>
#include <mach/host_priv.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 <ipc/ipc_types.h>
#include <ipc/ipc_space.h>
#include <ipc/ipc_entry.h>

#include <kern/kern_types.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 <kern/clock.h>
#include <kern/timer.h>
#include <kern/profile.h>
#include <kern/assert.h>
#include <kern/sync_lock.h>

#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>         /* for kernel_map, ipc_kernel_map */
#include <vm/vm_pageout.h>
#include <vm/vm_protos.h>       /* for vm_map_remove_commpage64 */

#if     MACH_KDB
#include <ddb/db_sym.h>
#endif  /* MACH_KDB */

#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 <mach/mach_port_server.h>

#include <vm/task_working_set.h>
#include <vm/vm_shared_memory_server.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_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_backing_store_privileged(
                        task_t task)
{
        task_lock(task);
        task->priv_flags |= VM_BACKING_STORE_PRIV;
        task_unlock(task);
        return;
}

void
task_working_set_disable(task_t task)
{
        struct tws_hash *ws;

        task_lock(task);
        ws = task->dynamic_working_set;
        task->dynamic_working_set = NULL;
        task_unlock(task);
        if (ws) {
                tws_hash_ws_flush(ws);
                tws_hash_destroy(ws);
        }
}

void
task_set_64bit(
                task_t task,
                boolean_t is64bit)
{
        if(is64bit) {
                /* LP64todo - no task working set for 64-bit */
                task_set_64BitAddr(task);
                task_working_set_disable(task);
                task->map->max_offset = MACH_VM_MAX_ADDRESS;
        } else {
                /*
                 * Deallocate all memory previously allocated
                 * above the 32-bit address space, since it won't
                 * be accessible anymore.
                 */
                /* LP64todo - make this clean */
#ifdef __ppc__
                vm_map_remove_commpage64(task->map);
                pmap_unmap_sharedpage(task->map->pmap); /* Unmap commpage */
#endif
                (void) vm_map_remove(task->map,
                                     (vm_map_offset_t) VM_MAX_ADDRESS,
                                     MACH_VM_MAX_ADDRESS,
                                     VM_MAP_NO_FLAGS);
                task_clear_64BitAddr(task);
                task->map->max_offset = (vm_map_offset_t)VM_MAX_ADDRESS;
        }
}

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

        /*
         * Create the kernel task as the first task.
         */
        if (task_create_internal(TASK_NULL, FALSE, &kernel_task) != KERN_SUCCESS)
                panic("task_init\n");

        vm_map_deallocate(kernel_task->map);
        kernel_task->map = kernel_map;
}

#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(
        __unused task_t         parent_task,
        __unused vm_offset_t            map_base,
        __unused vm_size_t              map_size,
        __unused task_t         *child_task)
{
        return (KERN_INVALID_ARGUMENT);
}

kern_return_t
task_create(
        task_t                                  parent_task,
        __unused ledger_port_array_t    ledger_ports,
        __unused  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_internal(
                        parent_task, inherit_memory, child_task);
}

kern_return_t
host_security_create_task_token(
        host_security_t                 host_security,
        task_t                                  parent_task,
        security_token_t                        sec_token,
        audit_token_t                           audit_token,
        host_priv_t                             host_priv,
        __unused ledger_port_array_t    ledger_ports,
        __unused 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_internal(
                        parent_task, inherit_memory, child_task);

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

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

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

        return(result);
}

kern_return_t
task_create_internal(
        task_t          parent_task,
        boolean_t       inherit_memory,
        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),
                                        (vm_map_offset_t)(VM_MIN_ADDRESS),
                                        (vm_map_offset_t)(VM_MAX_ADDRESS), TRUE);

        mutex_init(&new_task->lock, 0);
        queue_init(&new_task->threads);
        new_task->suspend_count = 0;
        new_task->thread_count = 0;
        new_task->active_thread_count = 0;
        new_task->user_stop_count = 0;
        new_task->role = TASK_UNSPECIFIED;
        new_task->active = TRUE;
        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->priv_flags = 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(BootProcInfo.pf.Available & pf64Bit) new_task->taskFeatures[0] |= tf64BitData;       /* If 64-bit machine, show we have 64-bit registers at least */
#endif

        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 */

        ipc_task_init(new_task, parent_task);

        new_task->total_user_time = 0;
        new_task->total_system_time = 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;
                new_task->audit_token = parent_task->audit_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));
                if(task_has_64BitAddr(parent_task))
                        task_set_64BitAddr(new_task);
        }
        else {
                pset = &default_pset;

                new_task->sec_token = KERNEL_SECURITY_TOKEN;
                new_task->audit_token = KERNEL_AUDIT_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 = BASEPRI_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 (vm_backing_store_low && parent_task != NULL)
                new_task->priv_flags |= (parent_task->priv_flags&VM_BACKING_STORE_PRIV);

        ipc_task_enable(new_task);

        *child_task = new_task;
        return(KERN_SUCCESS);
}

/*
 *      task_deallocate:
 *
 *      Drop a reference on a task.
 */
void
task_deallocate(
        task_t          task)
{
        processor_set_t         pset;

        if (task == TASK_NULL)
            return;

        if (task_deallocate_internal(task) > 0)
                return;

        pset = task->processor_set;
        pset_deallocate(pset);

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

        ipc_task_terminate(task);

        vm_map_deallocate(task->map);
        is_release(task->itk_space);

        task_prof_deallocate(task);
        zfree(task_zone, task);
}

/*
 *      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)
{
        processor_set_t         pset;
        thread_t                        thread, self;
        task_t                          self_task;
        boolean_t                       interrupt_save;

        assert(task != kernel_task);

        self = current_thread();
        self_task = self->task;

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

        if (!task->active || !self->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 (self_task != task)
                        task_unlock(self_task);

                return (KERN_FAILURE);
        }

        if (self_task != task)
                task_unlock(self_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 thread in the task.
         */
        queue_iterate(&task->threads, thread, thread_t, task_threads) {
                        thread_terminate_internal(thread);
        }

        /*
         *      Give the machine dependent code a chance
         *      to perform cleanup before ripping apart
         *      the task.
         */
        if (self_task == task)
                machine_thread_terminate_self();

        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.
         */
        ipc_space_destroy(task->itk_space);

/* LP64todo - make this clean */
#ifdef __ppc__
        vm_map_remove_commpage64(task->map);
        pmap_unmap_sharedpage(task->map->pmap);         /* Unmap commpage */
#endif

        /*
         * 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.
         */
        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(task->dynamic_working_set);

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

        /*
         * 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_t        thread, self;

        assert(task != kernel_task);

        self = current_thread();

        if (task != self->task)
                return (KERN_INVALID_ARGUMENT);

        task_lock(task);

        if (!task->active || !self->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->thread_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 threads in the task.
                 */
                queue_iterate(&task->threads, thread, thread_t, task_threads) {
                        if (thread != self)
                                thread_terminate_internal(thread);
                }

                task_release_locked(task);
        }

        /*
         *      Give the machine dependent code a chance
         *      to perform cleanup before ripping apart
         *      the task.
         */
        machine_thread_terminate_self();

        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.
         */
        ipc_space_clean(task->itk_space);

        /*
         * Clean out the address space, as we are going to be
         * getting a new one.
         */
        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_t       thread;

        assert(task->active);

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

        /*
         *      Iterate through all the threads and hold them.
         */
        queue_iterate(&task->threads, thread, thread_t, task_threads) {
                thread_mtx_lock(thread);
                thread_hold(thread);
                thread_mtx_unlock(thread);
        }
}

/*
 *      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(
        register task_t         task)
{
        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);
}

/*
 *      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_t       thread, self;

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

        self = current_thread();

        /*
         *      Iterate through all the threads and wait for them to
         *      stop.  Do not wait for the current thread if it is within
         *      the task.
         */
        queue_iterate(&task->threads, thread, thread_t, task_threads) {
                if (thread != self)
                        thread_wait(thread);
        }
}

/*
 *      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_t       thread;

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

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

        queue_iterate(&task->threads, thread, thread_t, task_threads) {
                thread_mtx_lock(thread);
                thread_release(thread);
                thread_mtx_unlock(thread);
        }
}

/*
 *      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)
{
        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              *threads_out,
        mach_msg_type_number_t  *count)
{
        mach_msg_type_number_t  actual;
        thread_t                                *threads;
        thread_t                                thread;
        vm_size_t                               size, size_needed;
        void                                    *addr;
        unsigned int                    i, j;

        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->thread_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 */
        threads = (thread_t *)addr;

        i = j = 0;

        for (thread = (thread_t)queue_first(&task->threads); i < actual;
                                ++i, thread = (thread_t)queue_next(&thread->task_threads)) {
                thread_reference_internal(thread);
                threads[j++] = thread;
        }

        assert(queue_end(&task->threads, (queue_entry_t)thread));

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

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

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

                *threads_out = 0;
                *count = 0;

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

                if (size_needed < size) {
                        void *newaddr;

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

                        bcopy(addr, newaddr, size_needed);
                        kfree(addr, size);
                        threads = (thread_t *)newaddr;
                }

                *threads_out = threads;
                *count = actual;

                /* do the conversion that Mig should handle */

                for (i = 0; i < actual; ++i)
                        ((ipc_port_t *) threads)[i] = convert_thread_to_port(threads[i]);
        }

        return (KERN_SUCCESS);
}

/*
 *      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 || task == kernel_task)
                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);
}

/*
 *      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 = FALSE;

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

        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,
        audit_token_t    audit_token,
        host_priv_t      host_priv)
{
        ipc_port_t       host_port;
        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->audit_token = audit_token;
        task_unlock(task);

        if (host_priv != HOST_PRIV_NULL) {
                kr = host_get_host_priv_port(host_priv, &host_port);
        } else {
                kr = host_get_host_port(host_priv_self(), &host_port);
        }
        assert(kr == KERN_SUCCESS);
        kr = task_set_special_port(task, TASK_HOST_PORT, host_port);
        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,
        __unused task_info_t    task_info_in,           /* pointer to IN array */
        __unused mach_msg_type_number_t task_info_count)
{
        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)
{
        if (task == TASK_NULL)
                return (KERN_INVALID_ARGUMENT);

        switch (flavor) {

        case TASK_BASIC_INFO_32:
        {
                task_basic_info_32_t    basic_info;
                vm_map_t                        map;

                if (*task_info_count < TASK_BASIC_INFO_32_COUNT)
                    return (KERN_INVALID_ARGUMENT);

                basic_info = (task_basic_info_32_t)task_info_out;

                map = (task == kernel_task)? kernel_map: task->map;
                basic_info->virtual_size  = CAST_DOWN(vm_offset_t,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;

                absolutetime_to_microtime(
                                                task->total_user_time,
                                                                &basic_info->user_time.seconds,
                                                                &basic_info->user_time.microseconds);
                absolutetime_to_microtime(
                                                task->total_system_time,
                                                                &basic_info->system_time.seconds,
                                                                &basic_info->system_time.microseconds);
                task_unlock(task);

                *task_info_count = TASK_BASIC_INFO_32_COUNT;
                break;
        }

        case TASK_BASIC_INFO_64:
        {
                task_basic_info_64_t    basic_info;
                vm_map_t                        map;

                if (*task_info_count < TASK_BASIC_INFO_64_COUNT)
                    return (KERN_INVALID_ARGUMENT);

                basic_info = (task_basic_info_64_t)task_info_out;

                map = (task == kernel_task)? kernel_map: task->map;
                basic_info->virtual_size  = map->size;
                basic_info->resident_size = (mach_vm_size_t)(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;

                absolutetime_to_microtime(
                                                task->total_user_time,
                                                                &basic_info->user_time.seconds,
                                                                &basic_info->user_time.microseconds);
                absolutetime_to_microtime(
                                                task->total_system_time,
                                                                &basic_info->system_time.seconds,
                                                                &basic_info->system_time.microseconds);
                task_unlock(task);

                *task_info_count = TASK_BASIC_INFO_64_COUNT;
                break;
        }

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

                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->threads, thread, thread_t, task_threads) {
                    time_value_t        user_time, system_time;

                    thread_read_times(thread, &user_time, &system_time);

                    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_ABSOLUTETIME_INFO:
        {
                task_absolutetime_info_t        info;
                register thread_t                       thread;

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

                info = (task_absolutetime_info_t)task_info_out;
                info->threads_user = info->threads_system = 0;

                task_lock(task);

                info->total_user = task->total_user_time;
                info->total_system = task->total_system_time;

                queue_iterate(&task->threads, thread, thread_t, task_threads) {
                        uint64_t        tval;

                        tval = timer_grab(&thread->user_timer);
                        info->threads_user += tval;
                        info->total_user += tval;

                        tval = timer_grab(&thread->system_timer);
                        info->threads_system += tval;
                        info->total_system += tval;
                }

                task_unlock(task);

                *task_info_count = TASK_ABSOLUTETIME_INFO_COUNT;
                break;
        }

        /* OBSOLETE */
        case TASK_SCHED_FIFO_INFO:
        {

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

                return (KERN_INVALID_POLICY);
        }

        /* OBSOLETE */
        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 = std_quantum_us / 1000;

                *task_info_count = POLICY_RR_BASE_COUNT;
                break;
        }

        /* OBSOLETE */
        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_AUDIT_TOKEN:
        {
                register audit_token_t  *audit_token_p;

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

                audit_token_p = (audit_token_t *) task_info_out;

                task_lock(task);
                *audit_token_p = task->audit_token;
                task_unlock(task);

                *task_info_count = TASK_AUDIT_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(
        __unused task_t         task,
        __unused processor_set_t        new_pset,
        __unused boolean_t      assign_threads)
{
        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(
        __unused task_t                 task,
        __unused policy_t                       policy_id,
        __unused policy_base_t          base,
        __unused mach_msg_type_number_t count,
        __unused boolean_t                      set_limit,
        __unused 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(
        __unused task_t                 task,
        __unused processor_set_t                pset,
        __unused policy_t                       policy_id,
        __unused policy_base_t          base,
        __unused mach_msg_type_number_t base_count,
        __unused policy_limit_t         limit,
        __unused mach_msg_type_number_t limit_count,
        __unused boolean_t                      change)
{
        return(KERN_FAILURE);
}

#if     FAST_TAS
kern_return_t
task_set_ras_pc(
        task_t          task,
        vm_offset_t     pc,
        vm_offset_t     endpc)
{
        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 */
kern_return_t
task_set_ras_pc(
        __unused task_t task,
        __unused vm_offset_t    pc,
        __unused vm_offset_t    endpc)
{
        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);
        }
}

/*
 * 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);

        return (FALSE);
}

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

#undef task_reference
void task_reference(task_t task);
void
task_reference(
        task_t          task)
{
        if (task != TASK_NULL)
                task_reference_internal(task);
}