xnu-7195.101.1.tar.gz

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

/*
 * Copyright (c) 2000-2020 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_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. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * 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_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * @OSF_FREE_COPYRIGHT@
 */
/*
 * Mach Operating System
 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
 * All Rights Reserved.
 *
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */
/*
 *      File:   kern/thread.c
 *      Author: Avadis Tevanian, Jr., Michael Wayne Young, David Golub
 *      Date:   1986
 *
 *      Thread 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/mach_types.h>
#include <mach/boolean.h>
#include <mach/policy.h>
#include <mach/thread_info.h>
#include <mach/thread_special_ports.h>
#include <mach/thread_status.h>
#include <mach/time_value.h>
#include <mach/vm_param.h>

#include <machine/thread.h>
#include <machine/pal_routines.h>
#include <machine/limits.h>

#include <kern/kern_types.h>
#include <kern/kalloc.h>
#include <kern/cpu_data.h>
#include <kern/extmod_statistics.h>
#include <kern/ipc_mig.h>
#include <kern/ipc_tt.h>
#include <kern/mach_param.h>
#include <kern/machine.h>
#include <kern/misc_protos.h>
#include <kern/processor.h>
#include <kern/queue.h>
#include <kern/sched.h>
#include <kern/sched_prim.h>
#include <kern/sync_lock.h>
#include <kern/syscall_subr.h>
#include <kern/task.h>
#include <kern/thread.h>
#include <kern/thread_group.h>
#include <kern/coalition.h>
#include <kern/host.h>
#include <kern/zalloc.h>
#include <kern/assert.h>
#include <kern/exc_resource.h>
#include <kern/exc_guard.h>
#include <kern/telemetry.h>
#include <kern/policy_internal.h>
#include <kern/turnstile.h>
#include <kern/sched_clutch.h>

#include <corpses/task_corpse.h>
#if KPC
#include <kern/kpc.h>
#endif

#if MONOTONIC
#include <kern/monotonic.h>
#include <machine/monotonic.h>
#endif /* MONOTONIC */

#include <ipc/ipc_kmsg.h>
#include <ipc/ipc_port.h>
#include <bank/bank_types.h>

#include <vm/vm_kern.h>
#include <vm/vm_pageout.h>

#include <sys/kdebug.h>
#include <sys/bsdtask_info.h>
#include <mach/sdt.h>
#include <san/kasan.h>
#if CONFIG_KSANCOV
#include <san/ksancov.h>
#endif

#include <stdatomic.h>

#if defined(HAS_APPLE_PAC)
#include <ptrauth.h>
#include <arm64/proc_reg.h>
#endif /* defined(HAS_APPLE_PAC) */

/*
 * Exported interfaces
 */
#include <mach/task_server.h>
#include <mach/thread_act_server.h>
#include <mach/mach_host_server.h>
#include <mach/host_priv_server.h>
#include <mach/mach_voucher_server.h>
#include <kern/policy_internal.h>

#if CONFIG_MACF
#include <security/mac_mach_internal.h>
#endif

LCK_GRP_DECLARE(thread_lck_grp, "thread");

ZONE_DECLARE(thread_zone, "threads", sizeof(struct thread), ZC_ZFREE_CLEARMEM);

ZONE_DECLARE(thread_qos_override_zone, "thread qos override",
    sizeof(struct thread_qos_override), ZC_NOENCRYPT);

static struct mpsc_daemon_queue thread_stack_queue;
static struct mpsc_daemon_queue thread_terminate_queue;
static struct mpsc_daemon_queue thread_deallocate_queue;
static struct mpsc_daemon_queue thread_exception_queue;

decl_simple_lock_data(static, crashed_threads_lock);
static queue_head_t             crashed_threads_queue;

struct thread_exception_elt {
        struct mpsc_queue_chain link;
        exception_type_t        exception_type;
        task_t                  exception_task;
        thread_t                exception_thread;
};

static SECURITY_READ_ONLY_LATE(struct thread) thread_template = {
#if MACH_ASSERT
        .thread_magic               = THREAD_MAGIC,
#endif /* MACH_ASSERT */
        .wait_result                = THREAD_WAITING,
        .options                    = THREAD_ABORTSAFE,
        .state                      = TH_WAIT | TH_UNINT,
        .th_sched_bucket            = TH_BUCKET_RUN,
        .base_pri                   = BASEPRI_DEFAULT,
        .realtime.deadline          = UINT64_MAX,
        .last_made_runnable_time    = THREAD_NOT_RUNNABLE,
        .last_basepri_change_time   = THREAD_NOT_RUNNABLE,
#if defined(CONFIG_SCHED_TIMESHARE_CORE)
        .pri_shift                  = INT8_MAX,
#endif
        /* timers are initialized in thread_bootstrap */
};

static struct thread init_thread;
static void thread_deallocate_enqueue(thread_t thread);
static void thread_deallocate_complete(thread_t thread);

#ifdef MACH_BSD
extern void proc_exit(void *);
extern mach_exception_data_type_t proc_encode_exit_exception_code(void *);
extern uint64_t get_dispatchqueue_offset_from_proc(void *);
extern uint64_t get_return_to_kernel_offset_from_proc(void *p);
extern int      proc_selfpid(void);
extern void     proc_name(int, char*, int);
extern char *   proc_name_address(void *p);
#endif /* MACH_BSD */

extern int disable_exc_resource;
extern int audio_active;
extern int debug_task;
int thread_max = CONFIG_THREAD_MAX;     /* Max number of threads */
int task_threadmax = CONFIG_THREAD_MAX;

static uint64_t         thread_unique_id = 100;

struct _thread_ledger_indices thread_ledgers = { .cpu_time = -1 };
static ledger_template_t thread_ledger_template = NULL;
static void init_thread_ledgers(void);

#if CONFIG_JETSAM
void jetsam_on_ledger_cpulimit_exceeded(void);
#endif

extern int task_thread_soft_limit;
extern int exc_via_corpse_forking;

#if DEVELOPMENT || DEBUG
extern int exc_resource_threads_enabled;
#endif /* DEVELOPMENT || DEBUG */

/*
 * Level (in terms of percentage of the limit) at which the CPU usage monitor triggers telemetry.
 *
 * (ie when any thread's CPU consumption exceeds 70% of the limit, start taking user
 *  stacktraces, aka micro-stackshots)
 */
#define CPUMON_USTACKSHOTS_TRIGGER_DEFAULT_PCT 70

/* Percentage. Level at which we start gathering telemetry. */
static TUNABLE(uint8_t, cpumon_ustackshots_trigger_pct,
    "cpumon_ustackshots_trigger_pct", CPUMON_USTACKSHOTS_TRIGGER_DEFAULT_PCT);
void __attribute__((noinline)) SENDING_NOTIFICATION__THIS_THREAD_IS_CONSUMING_TOO_MUCH_CPU(void);
#if DEVELOPMENT || DEBUG
void __attribute__((noinline)) SENDING_NOTIFICATION__TASK_HAS_TOO_MANY_THREADS(task_t, int);
#endif /* DEVELOPMENT || DEBUG */

/*
 * The smallest interval over which we support limiting CPU consumption is 1ms
 */
#define MINIMUM_CPULIMIT_INTERVAL_MS 1

os_refgrp_decl(static, thread_refgrp, "thread", NULL);

static inline void
init_thread_from_template(thread_t thread)
{
        /*
         * In general, struct thread isn't trivially-copyable, since it may
         * contain pointers to thread-specific state.  This may be enforced at
         * compile time on architectures that store authed + diversified
         * pointers in machine_thread.
         *
         * In this specific case, where we're initializing a new thread from a
         * thread_template, we know all diversified pointers are NULL; these are
         * safe to bitwise copy.
         */
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wnontrivial-memaccess"
        memcpy(thread, &thread_template, sizeof(*thread));
#pragma clang diagnostic pop
}

thread_t
thread_bootstrap(void)
{
        /*
         *      Fill in a template thread for fast initialization.
         */
        timer_init(&thread_template.user_timer);
        timer_init(&thread_template.system_timer);
        timer_init(&thread_template.ptime);
        timer_init(&thread_template.runnable_timer);

        init_thread_from_template(&init_thread);
        /* fiddle with init thread to skip asserts in set_sched_pri */
        init_thread.sched_pri = MAXPRI_KERNEL;
#if DEBUG || DEVELOPMENT
        queue_init(&init_thread.t_temp_alloc_list);
#endif /* DEBUG || DEVELOPMENT */

        return &init_thread;
}

void
thread_machine_init_template(void)
{
        machine_thread_template_init(&thread_template);
}

void
thread_init(void)
{
        stack_init();

        thread_policy_init();

        /*
         *      Initialize any machine-dependent
         *      per-thread structures necessary.
         */
        machine_thread_init();

        init_thread_ledgers();
}

boolean_t
thread_is_active(thread_t thread)
{
        return thread->active;
}

void
thread_corpse_continue(void)
{
        thread_t thread = current_thread();

        thread_terminate_internal(thread, TH_TERMINATE_OPTION_NONE);

        /*
         * Handle the thread termination directly
         * here instead of returning to userspace.
         */
        assert(thread->active == FALSE);
        thread_ast_clear(thread, AST_APC);
        thread_apc_ast(thread);

        panic("thread_corpse_continue");
        /*NOTREACHED*/
}

__dead2
static void
thread_terminate_continue(void)
{
        panic("thread_terminate_continue");
        /*NOTREACHED*/
}

/*
 *      thread_terminate_self:
 */
void
thread_terminate_self(void)
{
        thread_t                thread = current_thread();
        task_t                  task;
        int threadcnt;

        if (thread->t_temp_alloc_count) {
                kheap_temp_leak_panic(thread);
        }

        pal_thread_terminate_self(thread);

        DTRACE_PROC(lwp__exit);

        thread_mtx_lock(thread);

        ipc_thread_disable(thread);

        thread_mtx_unlock(thread);

        thread_sched_call(thread, NULL);

        spl_t s = splsched();
        thread_lock(thread);

        thread_depress_abort_locked(thread);

        thread_unlock(thread);
        splx(s);

#if CONFIG_TASKWATCH
        thead_remove_taskwatch(thread);
#endif /* CONFIG_TASKWATCH */

        work_interval_thread_terminate(thread);

        thread_mtx_lock(thread);

        thread_policy_reset(thread);

        thread_mtx_unlock(thread);

        assert(thread->th_work_interval == NULL);

        bank_swap_thread_bank_ledger(thread, NULL);

        if (kdebug_enable && bsd_hasthreadname(thread->uthread)) {
                char threadname[MAXTHREADNAMESIZE];
                bsd_getthreadname(thread->uthread, threadname);
                kernel_debug_string_simple(TRACE_STRING_THREADNAME_PREV, threadname);
        }

        task = thread->task;
        uthread_cleanup(task, thread->uthread, task->bsd_info);

        if (kdebug_enable && task->bsd_info && !task_is_exec_copy(task)) {
                /* trace out pid before we sign off */
                long dbg_arg1 = 0;
                long dbg_arg2 = 0;

                kdbg_trace_data(thread->task->bsd_info, &dbg_arg1, &dbg_arg2);
#if MONOTONIC
                if (kdebug_debugid_enabled(DBG_MT_INSTRS_CYCLES_THR_EXIT)) {
                        uint64_t counts[MT_CORE_NFIXED];
                        uint64_t thread_user_time;
                        uint64_t thread_system_time;
                        thread_user_time = timer_grab(&thread->user_timer);
                        thread_system_time = timer_grab(&thread->system_timer);
                        mt_fixed_thread_counts(thread, counts);
                        KDBG_RELEASE(DBG_MT_INSTRS_CYCLES_THR_EXIT,
#ifdef MT_CORE_INSTRS
                            counts[MT_CORE_INSTRS],
#else /* defined(MT_CORE_INSTRS) */
                            0,
#endif/* !defined(MT_CORE_INSTRS) */
                            counts[MT_CORE_CYCLES],
                            thread_system_time, thread_user_time);
                }
#endif/* MONOTONIC */
                KDBG_RELEASE(TRACE_DATA_THREAD_TERMINATE_PID, dbg_arg1, dbg_arg2);
        }

        /*
         * After this subtraction, this thread should never access
         * task->bsd_info unless it got 0 back from the os_atomic_dec.  It
         * could be racing with other threads to be the last thread in the
         * process, and the last thread in the process will tear down the proc
         * structure and zero-out task->bsd_info.
         */
        threadcnt = os_atomic_dec(&task->active_thread_count, relaxed);

        /*
         * If we are the last thread to terminate and the task is
         * associated with a BSD process, perform BSD process exit.
         */
        if (threadcnt == 0 && task->bsd_info != NULL && !task_is_exec_copy(task)) {
                mach_exception_data_type_t subcode = 0;
                if (kdebug_enable) {
                        /* since we're the last thread in this process, trace out the command name too */
                        long args[4] = {};
                        kdbg_trace_string(thread->task->bsd_info, &args[0], &args[1], &args[2], &args[3]);
#if MONOTONIC
                        if (kdebug_debugid_enabled(DBG_MT_INSTRS_CYCLES_PROC_EXIT)) {
                                uint64_t counts[MT_CORE_NFIXED];
                                uint64_t task_user_time;
                                uint64_t task_system_time;
                                mt_fixed_task_counts(task, counts);
                                /* since the thread time is not yet added to the task */
                                task_user_time = task->total_user_time + timer_grab(&thread->user_timer);
                                task_system_time = task->total_system_time + timer_grab(&thread->system_timer);
                                KDBG_RELEASE((DBG_MT_INSTRS_CYCLES_PROC_EXIT),
#ifdef MT_CORE_INSTRS
                                    counts[MT_CORE_INSTRS],
#else /* defined(MT_CORE_INSTRS) */
                                    0,
#endif/* !defined(MT_CORE_INSTRS) */
                                    counts[MT_CORE_CYCLES],
                                    task_system_time, task_user_time);
                        }
#endif/* MONOTONIC */
                        KDBG_RELEASE(TRACE_STRING_PROC_EXIT, args[0], args[1], args[2], args[3]);
                }

                /* Get the exit reason before proc_exit */
                subcode = proc_encode_exit_exception_code(task->bsd_info);
                proc_exit(task->bsd_info);
                /*
                 * if there is crash info in task
                 * then do the deliver action since this is
                 * last thread for this task.
                 */
                if (task->corpse_info) {
                        task_deliver_crash_notification(task, current_thread(), EXC_RESOURCE, subcode);
                }
        }

        if (threadcnt == 0) {
                task_lock(task);
                if (task_is_a_corpse_fork(task)) {
                        thread_wakeup((event_t)&task->active_thread_count);
                }
                task_unlock(task);
        }

        uthread_cred_free(thread->uthread);

        s = splsched();
        thread_lock(thread);

        /*
         * Ensure that the depress timer is no longer enqueued,
         * so the timer (stored in the thread) can be safely deallocated
         *
         * TODO: build timer_call_cancel_wait
         */

        assert((thread->sched_flags & TH_SFLAG_DEPRESSED_MASK) == 0);

        uint32_t delay_us = 1;

        while (thread->depress_timer_active > 0) {
                thread_unlock(thread);
                splx(s);

                delay(delay_us++);

                if (delay_us > USEC_PER_SEC) {
                        panic("depress timer failed to inactivate!"
                            "thread: %p depress_timer_active: %d",
                            thread, thread->depress_timer_active);
                }

                s = splsched();
                thread_lock(thread);
        }

        /*
         *      Cancel wait timer, and wait for
         *      concurrent expirations.
         */
        if (thread->wait_timer_is_set) {
                thread->wait_timer_is_set = FALSE;

                if (timer_call_cancel(&thread->wait_timer)) {
                        thread->wait_timer_active--;
                }
        }

        delay_us = 1;

        while (thread->wait_timer_active > 0) {
                thread_unlock(thread);
                splx(s);

                delay(delay_us++);

                if (delay_us > USEC_PER_SEC) {
                        panic("wait timer failed to inactivate!"
                            "thread: %p wait_timer_active: %d",
                            thread, thread->wait_timer_active);
                }

                s = splsched();
                thread_lock(thread);
        }

        /*
         *      If there is a reserved stack, release it.
         */
        if (thread->reserved_stack != 0) {
                stack_free_reserved(thread);
                thread->reserved_stack = 0;
        }

        /*
         *      Mark thread as terminating, and block.
         */
        thread->state |= TH_TERMINATE;
        thread_mark_wait_locked(thread, THREAD_UNINT);

        assert((thread->sched_flags & TH_SFLAG_WAITQ_PROMOTED) == 0);
        assert((thread->sched_flags & TH_SFLAG_RW_PROMOTED) == 0);
        assert((thread->sched_flags & TH_SFLAG_EXEC_PROMOTED) == 0);
        assert((thread->sched_flags & TH_SFLAG_PROMOTED) == 0);
        assert((thread->sched_flags & TH_SFLAG_THREAD_GROUP_AUTO_JOIN) == 0);
        assert(thread->th_work_interval_flags == TH_WORK_INTERVAL_FLAGS_NONE);
        assert(thread->kern_promotion_schedpri == 0);
        assert(thread->waiting_for_mutex == NULL);
        assert(thread->rwlock_count == 0);
        assert(thread->handoff_thread == THREAD_NULL);
        assert(thread->th_work_interval == NULL);

        thread_unlock(thread);
        /* splsched */

        thread_block((thread_continue_t)thread_terminate_continue);
        /*NOTREACHED*/
}

static bool
thread_ref_release(thread_t thread)
{
        if (thread == THREAD_NULL) {
                return false;
        }

        assert_thread_magic(thread);

        return os_ref_release(&thread->ref_count) == 0;
}

/* Drop a thread refcount safely without triggering a zfree */
void
thread_deallocate_safe(thread_t thread)
{
        if (__improbable(thread_ref_release(thread))) {
                /* enqueue the thread for thread deallocate deamon to call thread_deallocate_complete */
                thread_deallocate_enqueue(thread);
        }
}

void
thread_deallocate(thread_t thread)
{
        if (__improbable(thread_ref_release(thread))) {
                thread_deallocate_complete(thread);
        }
}

void
thread_deallocate_complete(
        thread_t                        thread)
{
        task_t                          task;

        assert_thread_magic(thread);

        assert(os_ref_get_count(&thread->ref_count) == 0);

        if (!(thread->state & TH_TERMINATE2)) {
                panic("thread_deallocate: thread not properly terminated\n");
        }

        assert(thread->runq == PROCESSOR_NULL);

#if KPC
        kpc_thread_destroy(thread);
#endif

        ipc_thread_terminate(thread);

        proc_thread_qos_deallocate(thread);

        task = thread->task;

#ifdef MACH_BSD
        {
                void *ut = thread->uthread;

                thread->uthread = NULL;
                uthread_zone_free(ut);
        }
#endif /* MACH_BSD */

        if (thread->t_ledger) {
                ledger_dereference(thread->t_ledger);
        }
        if (thread->t_threadledger) {
                ledger_dereference(thread->t_threadledger);
        }

        assert(thread->turnstile != TURNSTILE_NULL);
        if (thread->turnstile) {
                turnstile_deallocate(thread->turnstile);
        }

        if (IPC_VOUCHER_NULL != thread->ith_voucher) {
                ipc_voucher_release(thread->ith_voucher);
        }

        if (thread->thread_io_stats) {
                kheap_free(KHEAP_DATA_BUFFERS, thread->thread_io_stats,
                    sizeof(struct io_stat_info));
        }

        if (thread->kernel_stack != 0) {
                stack_free(thread);
        }

        lck_mtx_destroy(&thread->mutex, &thread_lck_grp);
        machine_thread_destroy(thread);

        task_deallocate(task);

#if MACH_ASSERT
        assert_thread_magic(thread);
        thread->thread_magic = 0;
#endif /* MACH_ASSERT */

        lck_mtx_lock(&tasks_threads_lock);
        assert(terminated_threads_count > 0);
        queue_remove(&terminated_threads, thread, thread_t, threads);
        terminated_threads_count--;
        lck_mtx_unlock(&tasks_threads_lock);

        zfree(thread_zone, thread);
}

/*
 *      thread_inspect_deallocate:
 *
 *      Drop a thread inspection reference.
 */
void
thread_inspect_deallocate(
        thread_inspect_t                thread_inspect)
{
        return thread_deallocate((thread_t)thread_inspect);
}

/*
 *      thread_read_deallocate:
 *
 *      Drop a reference on thread read port.
 */
void
thread_read_deallocate(
        thread_read_t                thread_read)
{
        return thread_deallocate((thread_t)thread_read);
}


/*
 *      thread_exception_queue_invoke:
 *
 *      Deliver EXC_{RESOURCE,GUARD} exception
 */
static void
thread_exception_queue_invoke(mpsc_queue_chain_t elm,
    __assert_only mpsc_daemon_queue_t dq)
{
        struct thread_exception_elt *elt;
        task_t task;
        thread_t thread;
        exception_type_t etype;

        assert(dq == &thread_exception_queue);
        elt = mpsc_queue_element(elm, struct thread_exception_elt, link);

        etype = elt->exception_type;
        task = elt->exception_task;
        thread = elt->exception_thread;
        assert_thread_magic(thread);

        kfree(elt, sizeof(*elt));

        /* wait for all the threads in the task to terminate */
        task_lock(task);
        task_wait_till_threads_terminate_locked(task);
        task_unlock(task);

        /* Consumes the task ref returned by task_generate_corpse_internal */
        task_deallocate(task);
        /* Consumes the thread ref returned by task_generate_corpse_internal */
        thread_deallocate(thread);

        /* Deliver the notification, also clears the corpse. */
        task_deliver_crash_notification(task, thread, etype, 0);
}

/*
 *      thread_exception_enqueue:
 *
 *      Enqueue a corpse port to be delivered an EXC_{RESOURCE,GUARD}.
 */
void
thread_exception_enqueue(
        task_t          task,
        thread_t        thread,
        exception_type_t etype)
{
        assert(EXC_RESOURCE == etype || EXC_GUARD == etype);
        struct thread_exception_elt *elt = kalloc(sizeof(*elt));
        elt->exception_type = etype;
        elt->exception_task = task;
        elt->exception_thread = thread;

        mpsc_daemon_enqueue(&thread_exception_queue, &elt->link,
            MPSC_QUEUE_DISABLE_PREEMPTION);
}

/*
 *      thread_copy_resource_info
 *
 *      Copy the resource info counters from source
 *      thread to destination thread.
 */
void
thread_copy_resource_info(
        thread_t dst_thread,
        thread_t src_thread)
{
        dst_thread->c_switch = src_thread->c_switch;
        dst_thread->p_switch = src_thread->p_switch;
        dst_thread->ps_switch = src_thread->ps_switch;
        dst_thread->precise_user_kernel_time = src_thread->precise_user_kernel_time;
        dst_thread->user_timer = src_thread->user_timer;
        dst_thread->user_timer_save = src_thread->user_timer_save;
        dst_thread->system_timer = src_thread->system_timer;
        dst_thread->system_timer_save = src_thread->system_timer_save;
        dst_thread->runnable_timer = src_thread->runnable_timer;
        dst_thread->vtimer_user_save = src_thread->vtimer_user_save;
        dst_thread->vtimer_prof_save = src_thread->vtimer_prof_save;
        dst_thread->vtimer_rlim_save = src_thread->vtimer_rlim_save;
        dst_thread->vtimer_qos_save = src_thread->vtimer_qos_save;
        dst_thread->syscalls_unix = src_thread->syscalls_unix;
        dst_thread->syscalls_mach = src_thread->syscalls_mach;
        ledger_rollup(dst_thread->t_threadledger, src_thread->t_threadledger);
        *dst_thread->thread_io_stats = *src_thread->thread_io_stats;
}

static void
thread_terminate_queue_invoke(mpsc_queue_chain_t e,
    __assert_only mpsc_daemon_queue_t dq)
{
        thread_t thread = mpsc_queue_element(e, struct thread, mpsc_links);
        task_t task = thread->task;

        assert(dq == &thread_terminate_queue);

        task_lock(task);

        /*
         * if marked for crash reporting, skip reaping.
         * The corpse delivery thread will clear bit and enqueue
         * for reaping when done
         *
         * Note: the inspection field is set under the task lock
         *
         * FIXME[mad]: why enqueue for termination before `inspection` is false ?
         */
        if (__improbable(thread->inspection)) {
                simple_lock(&crashed_threads_lock, &thread_lck_grp);
                task_unlock(task);

                enqueue_tail(&crashed_threads_queue, &thread->runq_links);
                simple_unlock(&crashed_threads_lock);
                return;
        }


        task->total_user_time += timer_grab(&thread->user_timer);
        task->total_ptime += timer_grab(&thread->ptime);
        task->total_runnable_time += timer_grab(&thread->runnable_timer);
        if (thread->precise_user_kernel_time) {
                task->total_system_time += timer_grab(&thread->system_timer);
        } else {
                task->total_user_time += timer_grab(&thread->system_timer);
        }

        task->c_switch += thread->c_switch;
        task->p_switch += thread->p_switch;
        task->ps_switch += thread->ps_switch;

        task->syscalls_unix += thread->syscalls_unix;
        task->syscalls_mach += thread->syscalls_mach;

        task->task_timer_wakeups_bin_1 += thread->thread_timer_wakeups_bin_1;
        task->task_timer_wakeups_bin_2 += thread->thread_timer_wakeups_bin_2;
        task->task_gpu_ns += ml_gpu_stat(thread);
        task->task_energy += ml_energy_stat(thread);
        task->decompressions += thread->decompressions;

#if MONOTONIC
        mt_terminate_update(task, thread);
#endif /* MONOTONIC */

        thread_update_qos_cpu_time(thread);

        queue_remove(&task->threads, thread, thread_t, task_threads);
        task->thread_count--;

        /*
         * If the task is being halted, and there is only one thread
         * left in the task after this one, then wakeup that thread.
         */
        if (task->thread_count == 1 && task->halting) {
                thread_wakeup((event_t)&task->halting);
        }

        task_unlock(task);

        lck_mtx_lock(&tasks_threads_lock);
        queue_remove(&threads, thread, thread_t, threads);
        threads_count--;
        queue_enter(&terminated_threads, thread, thread_t, threads);
        terminated_threads_count++;
        lck_mtx_unlock(&tasks_threads_lock);

        thread_deallocate(thread);
}

static void
thread_deallocate_queue_invoke(mpsc_queue_chain_t e,
    __assert_only mpsc_daemon_queue_t dq)
{
        thread_t thread = mpsc_queue_element(e, struct thread, mpsc_links);

        assert(dq == &thread_deallocate_queue);

        thread_deallocate_complete(thread);
}

/*
 *      thread_terminate_enqueue:
 *
 *      Enqueue a terminating thread for final disposition.
 *
 *      Called at splsched.
 */
void
thread_terminate_enqueue(
        thread_t                thread)
{
        KDBG_RELEASE(TRACE_DATA_THREAD_TERMINATE, thread->thread_id);

        mpsc_daemon_enqueue(&thread_terminate_queue, &thread->mpsc_links,
            MPSC_QUEUE_DISABLE_PREEMPTION);
}

/*
 *      thread_deallocate_enqueue:
 *
 *      Enqueue a thread for final deallocation.
 */
static void
thread_deallocate_enqueue(
        thread_t                thread)
{
        mpsc_daemon_enqueue(&thread_deallocate_queue, &thread->mpsc_links,
            MPSC_QUEUE_DISABLE_PREEMPTION);
}

/*
 * thread_terminate_crashed_threads:
 * walk the list of crashed threads and put back set of threads
 * who are no longer being inspected.
 */
void
thread_terminate_crashed_threads(void)
{
        thread_t th_remove;

        simple_lock(&crashed_threads_lock, &thread_lck_grp);
        /*
         * loop through the crashed threads queue
         * to put any threads that are not being inspected anymore
         */

        qe_foreach_element_safe(th_remove, &crashed_threads_queue, runq_links) {
                /* make sure current_thread is never in crashed queue */
                assert(th_remove != current_thread());

                if (th_remove->inspection == FALSE) {
                        remqueue(&th_remove->runq_links);
                        mpsc_daemon_enqueue(&thread_terminate_queue, &th_remove->mpsc_links,
                            MPSC_QUEUE_NONE);
                }
        }

        simple_unlock(&crashed_threads_lock);
}

/*
 *      thread_stack_queue_invoke:
 *
 *      Perform stack allocation as required due to
 *      invoke failures.
 */
static void
thread_stack_queue_invoke(mpsc_queue_chain_t elm,
    __assert_only mpsc_daemon_queue_t dq)
{
        thread_t thread = mpsc_queue_element(elm, struct thread, mpsc_links);

        assert(dq == &thread_stack_queue);

        /* allocate stack with interrupts enabled so that we can call into VM */
        stack_alloc(thread);

        KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_STACK_WAIT) | DBG_FUNC_END, thread_tid(thread), 0, 0, 0, 0);

        spl_t s = splsched();
        thread_lock(thread);
        thread_setrun(thread, SCHED_PREEMPT | SCHED_TAILQ);
        thread_unlock(thread);
        splx(s);
}

/*
 *      thread_stack_enqueue:
 *
 *      Enqueue a thread for stack allocation.
 *
 *      Called at splsched.
 */
void
thread_stack_enqueue(
        thread_t                thread)
{
        KERNEL_DEBUG_CONSTANT(MACHDBG_CODE(DBG_MACH_SCHED, MACH_STACK_WAIT) | DBG_FUNC_START, thread_tid(thread), 0, 0, 0, 0);
        assert_thread_magic(thread);

        mpsc_daemon_enqueue(&thread_stack_queue, &thread->mpsc_links,
            MPSC_QUEUE_DISABLE_PREEMPTION);
}

void
thread_daemon_init(void)
{
        kern_return_t   result;

        thread_deallocate_daemon_init();

        thread_deallocate_daemon_register_queue(&thread_terminate_queue,
            thread_terminate_queue_invoke);

        thread_deallocate_daemon_register_queue(&thread_deallocate_queue,
            thread_deallocate_queue_invoke);

        simple_lock_init(&crashed_threads_lock, 0);
        queue_init(&crashed_threads_queue);

        result = mpsc_daemon_queue_init_with_thread(&thread_stack_queue,
            thread_stack_queue_invoke, BASEPRI_PREEMPT_HIGH,
            "daemon.thread-stack");
        if (result != KERN_SUCCESS) {
                panic("thread_daemon_init: thread_stack_daemon");
        }

        result = mpsc_daemon_queue_init_with_thread(&thread_exception_queue,
            thread_exception_queue_invoke, MINPRI_KERNEL,
            "daemon.thread-exception");
        if (result != KERN_SUCCESS) {
                panic("thread_daemon_init: thread_exception_daemon");
        }
}

__options_decl(thread_create_internal_options_t, uint32_t, {
        TH_OPTION_NONE          = 0x00,
        TH_OPTION_NOCRED        = 0x01,
        TH_OPTION_NOSUSP        = 0x02,
        TH_OPTION_WORKQ         = 0x04,
        TH_OPTION_IMMOVABLE     = 0x08,
        TH_OPTION_PINNED        = 0x10,
});

/*
 * Create a new thread.
 * Doesn't start the thread running.
 *
 * Task and tasks_threads_lock are returned locked on success.
 */
static kern_return_t
thread_create_internal(
        task_t                                  parent_task,
        integer_t                               priority,
        thread_continue_t                       continuation,
        void                                    *parameter,
        thread_create_internal_options_t        options,
        thread_t                                *out_thread)
{
        thread_t                                new_thread;
        static thread_t                         first_thread;
        ipc_thread_init_options_t init_options = IPC_THREAD_INIT_NONE;

        /*
         *      Allocate a thread and initialize static fields
         */
        if (first_thread == THREAD_NULL) {
                new_thread = first_thread = current_thread();
        } else {
                new_thread = (thread_t)zalloc(thread_zone);
        }
        if (new_thread == THREAD_NULL) {
                return KERN_RESOURCE_SHORTAGE;
        }

        if (new_thread != first_thread) {
                init_thread_from_template(new_thread);
        }

        if (options & TH_OPTION_PINNED) {
                init_options |= IPC_THREAD_INIT_PINNED;
        }

        if (options & TH_OPTION_IMMOVABLE) {
                init_options |= IPC_THREAD_INIT_IMMOVABLE;
        }

        os_ref_init_count(&new_thread->ref_count, &thread_refgrp, 2);
#if DEBUG || DEVELOPMENT
        queue_init(&new_thread->t_temp_alloc_list);
#endif /* DEBUG || DEVELOPMENT */

#ifdef MACH_BSD
        new_thread->uthread = uthread_alloc(parent_task, new_thread, (options & TH_OPTION_NOCRED) != 0);
        if (new_thread->uthread == NULL) {
#if MACH_ASSERT
                new_thread->thread_magic = 0;
#endif /* MACH_ASSERT */

                zfree(thread_zone, new_thread);
                return KERN_RESOURCE_SHORTAGE;
        }
#endif  /* MACH_BSD */

        if (machine_thread_create(new_thread, parent_task) != KERN_SUCCESS) {
#ifdef MACH_BSD
                void *ut = new_thread->uthread;

                new_thread->uthread = NULL;
                /* cred free may not be necessary */
                uthread_cleanup(parent_task, ut, parent_task->bsd_info);
                uthread_cred_free(ut);
                uthread_zone_free(ut);
#endif  /* MACH_BSD */

#if MACH_ASSERT
                new_thread->thread_magic = 0;
#endif /* MACH_ASSERT */

                zfree(thread_zone, new_thread);
                return KERN_FAILURE;
        }

        new_thread->task = parent_task;

        thread_lock_init(new_thread);
        wake_lock_init(new_thread);

        lck_mtx_init(&new_thread->mutex, &thread_lck_grp, LCK_ATTR_NULL);

        ipc_thread_init(new_thread, init_options);

        new_thread->continuation = continuation;
        new_thread->parameter = parameter;
        new_thread->inheritor_flags = TURNSTILE_UPDATE_FLAGS_NONE;
        priority_queue_init(&new_thread->sched_inheritor_queue);
        priority_queue_init(&new_thread->base_inheritor_queue);
#if CONFIG_SCHED_CLUTCH
        priority_queue_entry_init(&new_thread->th_clutch_runq_link);
        priority_queue_entry_init(&new_thread->th_clutch_pri_link);
#endif /* CONFIG_SCHED_CLUTCH */

#if CONFIG_SCHED_EDGE
        new_thread->th_bound_cluster_enqueued = false;
#endif /* CONFIG_SCHED_EDGE */

        /* Allocate I/O Statistics structure */
        new_thread->thread_io_stats = kheap_alloc(KHEAP_DATA_BUFFERS,
            sizeof(struct io_stat_info), Z_WAITOK | Z_ZERO);
        assert(new_thread->thread_io_stats != NULL);

#if KASAN
        kasan_init_thread(&new_thread->kasan_data);
#endif

#if CONFIG_KSANCOV
        new_thread->ksancov_data = NULL;
#endif

#if CONFIG_IOSCHED
        /* Clear out the I/O Scheduling info for AppleFSCompression */
        new_thread->decmp_upl = NULL;
#endif /* CONFIG_IOSCHED */

        new_thread->thread_region_page_shift = 0;

#if DEVELOPMENT || DEBUG
        task_lock(parent_task);
        uint16_t thread_limit = parent_task->task_thread_limit;
        if (exc_resource_threads_enabled &&
            thread_limit > 0 &&
            parent_task->thread_count >= thread_limit &&
            !parent_task->task_has_crossed_thread_limit &&
            !(parent_task->t_flags & TF_CORPSE)) {
                int thread_count = parent_task->thread_count;
                parent_task->task_has_crossed_thread_limit = TRUE;
                task_unlock(parent_task);
                SENDING_NOTIFICATION__TASK_HAS_TOO_MANY_THREADS(parent_task, thread_count);
        } else {
                task_unlock(parent_task);
        }
#endif

        lck_mtx_lock(&tasks_threads_lock);
        task_lock(parent_task);

        /*
         * Fail thread creation if parent task is being torn down or has too many threads
         * If the caller asked for TH_OPTION_NOSUSP, also fail if the parent task is suspended
         */
        if (parent_task->active == 0 || parent_task->halting ||
            (parent_task->suspend_count > 0 && (options & TH_OPTION_NOSUSP) != 0) ||
            (parent_task->thread_count >= task_threadmax && parent_task != kernel_task)) {
                task_unlock(parent_task);
                lck_mtx_unlock(&tasks_threads_lock);

#ifdef MACH_BSD
                {
                        void *ut = new_thread->uthread;

                        new_thread->uthread = NULL;
                        uthread_cleanup(parent_task, ut, parent_task->bsd_info);
                        /* cred free may not be necessary */
                        uthread_cred_free(ut);
                        uthread_zone_free(ut);
                }
#endif  /* MACH_BSD */
                ipc_thread_disable(new_thread);
                ipc_thread_terminate(new_thread);
                kheap_free(KHEAP_DATA_BUFFERS, new_thread->thread_io_stats,
                    sizeof(struct io_stat_info));
                lck_mtx_destroy(&new_thread->mutex, &thread_lck_grp);
                machine_thread_destroy(new_thread);
                zfree(thread_zone, new_thread);
                return KERN_FAILURE;
        }

        /* Protected by the tasks_threads_lock */
        new_thread->thread_id = ++thread_unique_id;

        /* New threads inherit any default state on the task */
        machine_thread_inherit_taskwide(new_thread, parent_task);

        task_reference_internal(parent_task);

        if (new_thread->task->rusage_cpu_flags & TASK_RUSECPU_FLAGS_PERTHR_LIMIT) {
                /*
                 * This task has a per-thread CPU limit; make sure this new thread
                 * gets its limit set too, before it gets out of the kernel.
                 */
                act_set_astledger(new_thread);
        }

        /* Instantiate a thread ledger. Do not fail thread creation if ledger creation fails. */
        if ((new_thread->t_threadledger = ledger_instantiate(thread_ledger_template,
            LEDGER_CREATE_INACTIVE_ENTRIES)) != LEDGER_NULL) {
                ledger_entry_setactive(new_thread->t_threadledger, thread_ledgers.cpu_time);
        }

        new_thread->t_bankledger = LEDGER_NULL;
        new_thread->t_deduct_bank_ledger_time = 0;
        new_thread->t_deduct_bank_ledger_energy = 0;

        new_thread->t_ledger = new_thread->task->ledger;
        if (new_thread->t_ledger) {
                ledger_reference(new_thread->t_ledger);
        }

#if defined(CONFIG_SCHED_MULTIQ)
        /* Cache the task's sched_group */
        new_thread->sched_group = parent_task->sched_group;
#endif /* defined(CONFIG_SCHED_MULTIQ) */

        /* Cache the task's map */
        new_thread->map = parent_task->map;

        timer_call_setup(&new_thread->wait_timer, thread_timer_expire, new_thread);
        timer_call_setup(&new_thread->depress_timer, thread_depress_expire, new_thread);

#if KPC
        kpc_thread_create(new_thread);
#endif

        /* Set the thread's scheduling parameters */
        new_thread->sched_mode = SCHED(initial_thread_sched_mode)(parent_task);
        new_thread->max_priority = parent_task->max_priority;
        new_thread->task_priority = parent_task->priority;

#if CONFIG_THREAD_GROUPS
        thread_group_init_thread(new_thread, parent_task);
#endif /* CONFIG_THREAD_GROUPS */

        int new_priority = (priority < 0) ? parent_task->priority: priority;
        new_priority = (priority < 0)? parent_task->priority: priority;
        if (new_priority > new_thread->max_priority) {
                new_priority = new_thread->max_priority;
        }
#if !defined(XNU_TARGET_OS_OSX)
        if (new_priority < MAXPRI_THROTTLE) {
                new_priority = MAXPRI_THROTTLE;
        }
#endif /* !defined(XNU_TARGET_OS_OSX) */

        new_thread->importance = new_priority - new_thread->task_priority;

        sched_set_thread_base_priority(new_thread, new_priority);

#if defined(CONFIG_SCHED_TIMESHARE_CORE)
        new_thread->sched_stamp = sched_tick;
#if CONFIG_SCHED_CLUTCH
        new_thread->pri_shift = sched_clutch_thread_pri_shift(new_thread, new_thread->th_sched_bucket);
#else /* CONFIG_SCHED_CLUTCH */
        new_thread->pri_shift = sched_pri_shifts[new_thread->th_sched_bucket];
#endif /* CONFIG_SCHED_CLUTCH */
#endif /* defined(CONFIG_SCHED_TIMESHARE_CORE) */

        if (parent_task->max_priority <= MAXPRI_THROTTLE) {
                sched_thread_mode_demote(new_thread, TH_SFLAG_THROTTLED);
        }

        thread_policy_create(new_thread);

        /* Chain the thread onto the task's list */
        queue_enter(&parent_task->threads, new_thread, thread_t, task_threads);
        parent_task->thread_count++;

        /* So terminating threads don't need to take the task lock to decrement */
        os_atomic_inc(&parent_task->active_thread_count, relaxed);

        queue_enter(&threads, new_thread, thread_t, threads);
        threads_count++;

        new_thread->active = TRUE;
        if (task_is_a_corpse_fork(parent_task)) {
                /* Set the inspection bit if the task is a corpse fork */
                new_thread->inspection = TRUE;
        } else {
                new_thread->inspection = FALSE;
        }
        new_thread->corpse_dup = FALSE;
        new_thread->turnstile = turnstile_alloc();


        *out_thread = new_thread;

        if (kdebug_enable) {
                long args[4] = {};

                kdbg_trace_data(parent_task->bsd_info, &args[1], &args[3]);

                /*
                 * Starting with 26604425, exec'ing creates a new task/thread.
                 *
                 * NEWTHREAD in the current process has two possible meanings:
                 *
                 * 1) Create a new thread for this process.
                 * 2) Create a new thread for the future process this will become in an
                 * exec.
                 *
                 * To disambiguate these, arg3 will be set to TRUE for case #2.
                 *
                 * The value we need to find (TPF_EXEC_COPY) is stable in the case of a
                 * task exec'ing. The read of t_procflags does not take the proc_lock.
                 */
                args[2] = task_is_exec_copy(parent_task) ? 1 : 0;

                KDBG_RELEASE(TRACE_DATA_NEWTHREAD, (uintptr_t)thread_tid(new_thread),
                    args[1], args[2], args[3]);

                kdbg_trace_string(parent_task->bsd_info, &args[0], &args[1],
                    &args[2], &args[3]);
                KDBG_RELEASE(TRACE_STRING_NEWTHREAD, args[0], args[1], args[2],
                    args[3]);
        }

        DTRACE_PROC1(lwp__create, thread_t, *out_thread);

        return KERN_SUCCESS;
}

static kern_return_t
thread_create_with_options_internal(
        task_t                            task,
        thread_t                          *new_thread,
        boolean_t                         from_user,
        thread_create_internal_options_t  options,
        thread_continue_t                 continuation)
{
        kern_return_t           result;
        thread_t                thread;

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

#if CONFIG_MACF
        if (from_user && current_task() != task &&
            mac_proc_check_remote_thread_create(task, -1, NULL, 0) != 0) {
                return KERN_DENIED;
        }
#endif

        result = thread_create_internal(task, -1, continuation, NULL, options, &thread);
        if (result != KERN_SUCCESS) {
                return result;
        }

        thread->user_stop_count = 1;
        thread_hold(thread);
        if (task->suspend_count > 0) {
                thread_hold(thread);
        }

        if (from_user) {
                extmod_statistics_incr_thread_create(task);
        }

        task_unlock(task);
        lck_mtx_unlock(&tasks_threads_lock);

        *new_thread = thread;

        return KERN_SUCCESS;
}

/* No prototype, since task_server.h has the _from_user version if KERNEL_SERVER */
kern_return_t
thread_create(
        task_t                          task,
        thread_t                        *new_thread);

kern_return_t
thread_create(
        task_t                          task,
        thread_t                        *new_thread)
{
        return thread_create_with_options_internal(task, new_thread, FALSE, TH_OPTION_NONE,
                   (thread_continue_t)thread_bootstrap_return);
}

/*
 * Create a thread that has its itk_self pinned
 * Deprecated, should be cleanup once rdar://70892168 lands
 */
kern_return_t
thread_create_pinned(
        task_t                          task,
        thread_t                        *new_thread)
{
        return thread_create_with_options_internal(task, new_thread, FALSE,
                   TH_OPTION_PINNED | TH_OPTION_IMMOVABLE, (thread_continue_t)thread_bootstrap_return);
}

kern_return_t
thread_create_immovable(
        task_t                          task,
        thread_t                        *new_thread)
{
        return thread_create_with_options_internal(task, new_thread, FALSE,
                   TH_OPTION_IMMOVABLE, (thread_continue_t)thread_bootstrap_return);
}

kern_return_t
thread_create_from_user(
        task_t                          task,
        thread_t                        *new_thread)
{
        return thread_create_with_options_internal(task, new_thread, TRUE, TH_OPTION_NONE,
                   (thread_continue_t)thread_bootstrap_return);
}

kern_return_t
thread_create_with_continuation(
        task_t                          task,
        thread_t                        *new_thread,
        thread_continue_t               continuation)
{
        return thread_create_with_options_internal(task, new_thread, FALSE, TH_OPTION_NONE, continuation);
}

/*
 * Create a thread that is already started, but is waiting on an event
 */
static kern_return_t
thread_create_waiting_internal(
        task_t                  task,
        thread_continue_t       continuation,
        event_t                 event,
        block_hint_t            block_hint,
        int                     options,
        thread_t                *new_thread)
{
        kern_return_t result;
        thread_t thread;

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

        result = thread_create_internal(task, -1, continuation, NULL,
            options, &thread);
        if (result != KERN_SUCCESS) {
                return result;
        }

        /* note no user_stop_count or thread_hold here */

        if (task->suspend_count > 0) {
                thread_hold(thread);
        }

        thread_mtx_lock(thread);
        thread_set_pending_block_hint(thread, block_hint);
        if (options & TH_OPTION_WORKQ) {
                thread->static_param = true;
                event = workq_thread_init_and_wq_lock(task, thread);
        }
        thread_start_in_assert_wait(thread, event, THREAD_INTERRUPTIBLE);
        thread_mtx_unlock(thread);

        task_unlock(task);
        lck_mtx_unlock(&tasks_threads_lock);

        *new_thread = thread;

        return KERN_SUCCESS;
}

kern_return_t
thread_create_waiting(
        task_t                          task,
        thread_continue_t               continuation,
        event_t                         event,
        th_create_waiting_options_t     options,
        thread_t                        *new_thread)
{
        thread_create_internal_options_t ci_options = TH_OPTION_NONE;

        assert((options & ~TH_CREATE_WAITING_OPTION_MASK) == 0);
        if (options & TH_CREATE_WAITING_OPTION_PINNED) {
                ci_options |= TH_OPTION_PINNED;
        }
        if (options & TH_CREATE_WAITING_OPTION_IMMOVABLE) {
                ci_options |= TH_OPTION_IMMOVABLE;
        }

        return thread_create_waiting_internal(task, continuation, event,
                   kThreadWaitNone, ci_options, new_thread);
}


static kern_return_t
thread_create_running_internal2(
        task_t         task,
        int                     flavor,
        thread_state_t          new_state,
        mach_msg_type_number_t  new_state_count,
        thread_t                                *new_thread,
        boolean_t                               from_user)
{
        kern_return_t  result;
        thread_t                                thread;

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

#if CONFIG_MACF
        if (from_user && current_task() != task &&
            mac_proc_check_remote_thread_create(task, flavor, new_state, new_state_count) != 0) {
                return KERN_DENIED;
        }
#endif

        result = thread_create_internal(task, -1,
            (thread_continue_t)thread_bootstrap_return, NULL,
            TH_OPTION_NONE, &thread);
        if (result != KERN_SUCCESS) {
                return result;
        }

        if (task->suspend_count > 0) {
                thread_hold(thread);
        }

        if (from_user) {
                result = machine_thread_state_convert_from_user(thread, flavor,
                    new_state, new_state_count);
        }
        if (result == KERN_SUCCESS) {
                result = machine_thread_set_state(thread, flavor, new_state,
                    new_state_count);
        }
        if (result != KERN_SUCCESS) {
                task_unlock(task);
                lck_mtx_unlock(&tasks_threads_lock);

                thread_terminate(thread);
                thread_deallocate(thread);
                return result;
        }

        thread_mtx_lock(thread);
        thread_start(thread);
        thread_mtx_unlock(thread);

        if (from_user) {
                extmod_statistics_incr_thread_create(task);
        }

        task_unlock(task);
        lck_mtx_unlock(&tasks_threads_lock);

        *new_thread = thread;

        return result;
}

/* Prototype, see justification above */
kern_return_t
thread_create_running(
        task_t         task,
        int                     flavor,
        thread_state_t          new_state,
        mach_msg_type_number_t  new_state_count,
        thread_t                                *new_thread);

kern_return_t
thread_create_running(
        task_t         task,
        int                     flavor,
        thread_state_t          new_state,
        mach_msg_type_number_t  new_state_count,
        thread_t                                *new_thread)
{
        return thread_create_running_internal2(
                task, flavor, new_state, new_state_count,
                new_thread, FALSE);
}

kern_return_t
thread_create_running_from_user(
        task_t         task,
        int                     flavor,
        thread_state_t          new_state,
        mach_msg_type_number_t  new_state_count,
        thread_t                                *new_thread)
{
        return thread_create_running_internal2(
                task, flavor, new_state, new_state_count,
                new_thread, TRUE);
}

kern_return_t
thread_create_workq_waiting(
        task_t              task,
        thread_continue_t   continuation,
        thread_t            *new_thread)
{
        /*
         * Create thread, but don't pin control port just yet, in case someone calls
         * task_threads() and deallocates pinned port before kernel copyout happens,
         * which will result in pinned port guard exception. Instead, pin and make
         * it immovable atomically at copyout during workq_setup_and_run().
         */
        int options = TH_OPTION_NOCRED | TH_OPTION_NOSUSP | TH_OPTION_WORKQ | TH_OPTION_IMMOVABLE;
        return thread_create_waiting_internal(task, continuation, NULL,
                   kThreadWaitParkedWorkQueue, options, new_thread);
}

/*
 *      kernel_thread_create:
 *
 *      Create a thread in the kernel task
 *      to execute in kernel context.
 */
kern_return_t
kernel_thread_create(
        thread_continue_t       continuation,
        void                            *parameter,
        integer_t                       priority,
        thread_t                        *new_thread)
{
        kern_return_t           result;
        thread_t                        thread;
        task_t                          task = kernel_task;

        result = thread_create_internal(task, priority, continuation, parameter,
            TH_OPTION_NOCRED | TH_OPTION_NONE, &thread);
        if (result != KERN_SUCCESS) {
                return result;
        }

        task_unlock(task);
        lck_mtx_unlock(&tasks_threads_lock);

        stack_alloc(thread);
        assert(thread->kernel_stack != 0);
#if !defined(XNU_TARGET_OS_OSX)
        if (priority > BASEPRI_KERNEL)
#endif
        thread->reserved_stack = thread->kernel_stack;

        if (debug_task & 1) {
                kprintf("kernel_thread_create: thread = %p continuation = %p\n", thread, continuation);
        }
        *new_thread = thread;

        return result;
}

kern_return_t
kernel_thread_start_priority(
        thread_continue_t       continuation,
        void                            *parameter,
        integer_t                       priority,
        thread_t                        *new_thread)
{
        kern_return_t   result;
        thread_t                thread;

        result = kernel_thread_create(continuation, parameter, priority, &thread);
        if (result != KERN_SUCCESS) {
                return result;
        }

        *new_thread = thread;

        thread_mtx_lock(thread);
        thread_start(thread);
        thread_mtx_unlock(thread);

        return result;
}

kern_return_t
kernel_thread_start(
        thread_continue_t       continuation,
        void                            *parameter,
        thread_t                        *new_thread)
{
        return kernel_thread_start_priority(continuation, parameter, -1, new_thread);
}

/* Separated into helper function so it can be used by THREAD_BASIC_INFO and THREAD_EXTENDED_INFO */
/* it is assumed that the thread is locked by the caller */
static void
retrieve_thread_basic_info(thread_t thread, thread_basic_info_t basic_info)
{
        int     state, flags;

        /* fill in info */

        thread_read_times(thread, &basic_info->user_time,
            &basic_info->system_time, NULL);

        /*
         *      Update lazy-evaluated scheduler info because someone wants it.
         */
        if (SCHED(can_update_priority)(thread)) {
                SCHED(update_priority)(thread);
        }

        basic_info->sleep_time = 0;

        /*
         *      To calculate cpu_usage, first correct for timer rate,
         *      then for 5/8 ageing.  The correction factor [3/5] is
         *      (1/(5/8) - 1).
         */
        basic_info->cpu_usage = 0;
#if defined(CONFIG_SCHED_TIMESHARE_CORE)
        if (sched_tick_interval) {
                basic_info->cpu_usage = (integer_t)(((uint64_t)thread->cpu_usage
                    * TH_USAGE_SCALE) /     sched_tick_interval);
                basic_info->cpu_usage = (basic_info->cpu_usage * 3) / 5;
        }
#endif

        if (basic_info->cpu_usage > TH_USAGE_SCALE) {
                basic_info->cpu_usage = TH_USAGE_SCALE;
        }

        basic_info->policy = ((thread->sched_mode == TH_MODE_TIMESHARE)?
            POLICY_TIMESHARE: POLICY_RR);

        flags = 0;
        if (thread->options & TH_OPT_IDLE_THREAD) {
                flags |= TH_FLAGS_IDLE;
        }

        if (thread->options & TH_OPT_GLOBAL_FORCED_IDLE) {
                flags |= TH_FLAGS_GLOBAL_FORCED_IDLE;
        }

        if (!thread->kernel_stack) {
                flags |= TH_FLAGS_SWAPPED;
        }

        state = 0;
        if (thread->state & TH_TERMINATE) {
                state = TH_STATE_HALTED;
        } else if (thread->state & TH_RUN) {
                state = TH_STATE_RUNNING;
        } else if (thread->state & TH_UNINT) {
                state = TH_STATE_UNINTERRUPTIBLE;
        } else if (thread->state & TH_SUSP) {
                state = TH_STATE_STOPPED;
        } else if (thread->state & TH_WAIT) {
                state = TH_STATE_WAITING;
        }

        basic_info->run_state = state;
        basic_info->flags = flags;

        basic_info->suspend_count = thread->user_stop_count;

        return;
}

kern_return_t
thread_info_internal(
        thread_t                thread,
        thread_flavor_t                 flavor,
        thread_info_t                   thread_info_out,        /* ptr to OUT array */
        mach_msg_type_number_t  *thread_info_count)     /*IN/OUT*/
{
        spl_t   s;

        if (thread == THREAD_NULL) {
                return KERN_INVALID_ARGUMENT;
        }

        if (flavor == THREAD_BASIC_INFO) {
                if (*thread_info_count < THREAD_BASIC_INFO_COUNT) {
                        return KERN_INVALID_ARGUMENT;
                }

                s = splsched();
                thread_lock(thread);

                retrieve_thread_basic_info(thread, (thread_basic_info_t) thread_info_out);

                thread_unlock(thread);
                splx(s);

                *thread_info_count = THREAD_BASIC_INFO_COUNT;

                return KERN_SUCCESS;
        } else if (flavor == THREAD_IDENTIFIER_INFO) {
                thread_identifier_info_t        identifier_info;

                if (*thread_info_count < THREAD_IDENTIFIER_INFO_COUNT) {
                        return KERN_INVALID_ARGUMENT;
                }

                identifier_info = __IGNORE_WCASTALIGN((thread_identifier_info_t)thread_info_out);

                s = splsched();
                thread_lock(thread);

                identifier_info->thread_id = thread->thread_id;
                identifier_info->thread_handle = thread->machine.cthread_self;
                identifier_info->dispatch_qaddr = thread_dispatchqaddr(thread);

                thread_unlock(thread);
                splx(s);
                return KERN_SUCCESS;
        } else if (flavor == THREAD_SCHED_TIMESHARE_INFO) {
                policy_timeshare_info_t         ts_info;

                if (*thread_info_count < POLICY_TIMESHARE_INFO_COUNT) {
                        return KERN_INVALID_ARGUMENT;
                }

                ts_info = (policy_timeshare_info_t)thread_info_out;

                s = splsched();
                thread_lock(thread);

                if (thread->sched_mode != TH_MODE_TIMESHARE) {
                        thread_unlock(thread);
                        splx(s);
                        return KERN_INVALID_POLICY;
                }

                ts_info->depressed = (thread->sched_flags & TH_SFLAG_DEPRESSED_MASK) != 0;
                if (ts_info->depressed) {
                        ts_info->base_priority = DEPRESSPRI;
                        ts_info->depress_priority = thread->base_pri;
                } else {
                        ts_info->base_priority = thread->base_pri;
                        ts_info->depress_priority = -1;
                }

                ts_info->cur_priority = thread->sched_pri;
                ts_info->max_priority = thread->max_priority;

                thread_unlock(thread);
                splx(s);

                *thread_info_count = POLICY_TIMESHARE_INFO_COUNT;

                return KERN_SUCCESS;
        } else if (flavor == THREAD_SCHED_FIFO_INFO) {
                if (*thread_info_count < POLICY_FIFO_INFO_COUNT) {
                        return KERN_INVALID_ARGUMENT;
                }

                return KERN_INVALID_POLICY;
        } else if (flavor == THREAD_SCHED_RR_INFO) {
                policy_rr_info_t                        rr_info;
                uint32_t quantum_time;
                uint64_t quantum_ns;

                if (*thread_info_count < POLICY_RR_INFO_COUNT) {
                        return KERN_INVALID_ARGUMENT;
                }

                rr_info = (policy_rr_info_t) thread_info_out;

                s = splsched();
                thread_lock(thread);

                if (thread->sched_mode == TH_MODE_TIMESHARE) {
                        thread_unlock(thread);
                        splx(s);

                        return KERN_INVALID_POLICY;
                }

                rr_info->depressed = (thread->sched_flags & TH_SFLAG_DEPRESSED_MASK) != 0;
                if (rr_info->depressed) {
                        rr_info->base_priority = DEPRESSPRI;
                        rr_info->depress_priority = thread->base_pri;
                } else {
                        rr_info->base_priority = thread->base_pri;
                        rr_info->depress_priority = -1;
                }

                quantum_time = SCHED(initial_quantum_size)(THREAD_NULL);
                absolutetime_to_nanoseconds(quantum_time, &quantum_ns);

                rr_info->max_priority = thread->max_priority;
                rr_info->quantum = (uint32_t)(quantum_ns / 1000 / 1000);

                thread_unlock(thread);
                splx(s);

                *thread_info_count = POLICY_RR_INFO_COUNT;

                return KERN_SUCCESS;
        } else if (flavor == THREAD_EXTENDED_INFO) {
                thread_basic_info_data_t        basic_info;
                thread_extended_info_t          extended_info = __IGNORE_WCASTALIGN((thread_extended_info_t)thread_info_out);

                if (*thread_info_count < THREAD_EXTENDED_INFO_COUNT) {
                        return KERN_INVALID_ARGUMENT;
                }

                s = splsched();
                thread_lock(thread);

                /* NOTE: This mimics fill_taskthreadinfo(), which is the function used by proc_pidinfo() for
                 * the PROC_PIDTHREADINFO flavor (which can't be used on corpses)
                 */
                retrieve_thread_basic_info(thread, &basic_info);
                extended_info->pth_user_time = (((uint64_t)basic_info.user_time.seconds * NSEC_PER_SEC) + ((uint64_t)basic_info.user_time.microseconds * NSEC_PER_USEC));
                extended_info->pth_system_time = (((uint64_t)basic_info.system_time.seconds * NSEC_PER_SEC) + ((uint64_t)basic_info.system_time.microseconds * NSEC_PER_USEC));

                extended_info->pth_cpu_usage = basic_info.cpu_usage;
                extended_info->pth_policy = basic_info.policy;
                extended_info->pth_run_state = basic_info.run_state;
                extended_info->pth_flags = basic_info.flags;
                extended_info->pth_sleep_time = basic_info.sleep_time;
                extended_info->pth_curpri = thread->sched_pri;
                extended_info->pth_priority = thread->base_pri;
                extended_info->pth_maxpriority = thread->max_priority;

                bsd_getthreadname(thread->uthread, extended_info->pth_name);

                thread_unlock(thread);
                splx(s);

                *thread_info_count = THREAD_EXTENDED_INFO_COUNT;

                return KERN_SUCCESS;
        } else if (flavor == THREAD_DEBUG_INFO_INTERNAL) {
#if DEVELOPMENT || DEBUG
                thread_debug_info_internal_t dbg_info;
                if (*thread_info_count < THREAD_DEBUG_INFO_INTERNAL_COUNT) {
                        return KERN_NOT_SUPPORTED;
                }

                if (thread_info_out == NULL) {
                        return KERN_INVALID_ARGUMENT;
                }

                dbg_info = __IGNORE_WCASTALIGN((thread_debug_info_internal_t)thread_info_out);
                dbg_info->page_creation_count = thread->t_page_creation_count;

                *thread_info_count = THREAD_DEBUG_INFO_INTERNAL_COUNT;
                return KERN_SUCCESS;
#endif /* DEVELOPMENT || DEBUG */
                return KERN_NOT_SUPPORTED;
        }

        return KERN_INVALID_ARGUMENT;
}

void
thread_read_times(
        thread_t                thread,
        time_value_t    *user_time,
        time_value_t    *system_time,
        time_value_t    *runnable_time)
{
        clock_sec_t             secs;
        clock_usec_t    usecs;
        uint64_t                tval_user, tval_system;

        tval_user = timer_grab(&thread->user_timer);
        tval_system = timer_grab(&thread->system_timer);

        if (thread->precise_user_kernel_time) {
                absolutetime_to_microtime(tval_user, &secs, &usecs);
                user_time->seconds = (typeof(user_time->seconds))secs;
                user_time->microseconds = usecs;

                absolutetime_to_microtime(tval_system, &secs, &usecs);
                system_time->seconds = (typeof(system_time->seconds))secs;
                system_time->microseconds = usecs;
        } else {
                /* system_timer may represent either sys or user */
                tval_user += tval_system;
                absolutetime_to_microtime(tval_user, &secs, &usecs);
                user_time->seconds = (typeof(user_time->seconds))secs;
                user_time->microseconds = usecs;

                system_time->seconds = 0;
                system_time->microseconds = 0;
        }

        if (runnable_time) {
                uint64_t tval_runnable = timer_grab(&thread->runnable_timer);
                absolutetime_to_microtime(tval_runnable, &secs, &usecs);
                runnable_time->seconds = (typeof(runnable_time->seconds))secs;
                runnable_time->microseconds = usecs;
        }
}

uint64_t
thread_get_runtime_self(void)
{
        boolean_t interrupt_state;
        uint64_t runtime;
        thread_t thread = NULL;
        processor_t processor = NULL;

        thread = current_thread();

        /* Not interrupt safe, as the scheduler may otherwise update timer values underneath us */
        interrupt_state = ml_set_interrupts_enabled(FALSE);
        processor = current_processor();
        timer_update(processor->thread_timer, mach_absolute_time());
        runtime = (timer_grab(&thread->user_timer) + timer_grab(&thread->system_timer));
        ml_set_interrupts_enabled(interrupt_state);

        return runtime;
}

kern_return_t
thread_assign(
        __unused thread_t                       thread,
        __unused processor_set_t        new_pset)
{
        return KERN_FAILURE;
}

/*
 *      thread_assign_default:
 *
 *      Special version of thread_assign for assigning threads to default
 *      processor set.
 */
kern_return_t
thread_assign_default(
        thread_t                thread)
{
        return thread_assign(thread, &pset0);
}

/*
 *      thread_get_assignment
 *
 *      Return current assignment for this thread.
 */
kern_return_t
thread_get_assignment(
        thread_t                thread,
        processor_set_t *pset)
{
        if (thread == NULL) {
                return KERN_INVALID_ARGUMENT;
        }

        *pset = &pset0;

        return KERN_SUCCESS;
}

/*
 *      thread_wire_internal:
 *
 *      Specify that the target thread must always be able
 *      to run and to allocate memory.
 */
kern_return_t
thread_wire_internal(
        host_priv_t             host_priv,
        thread_t                thread,
        boolean_t               wired,
        boolean_t               *prev_state)
{
        if (host_priv == NULL || thread != current_thread()) {
                return KERN_INVALID_ARGUMENT;
        }

        if (prev_state) {
                *prev_state = (thread->options & TH_OPT_VMPRIV) != 0;
        }

        if (wired) {
                if (!(thread->options & TH_OPT_VMPRIV)) {
                        vm_page_free_reserve(1); /* XXX */
                }
                thread->options |= TH_OPT_VMPRIV;
        } else {
                if (thread->options & TH_OPT_VMPRIV) {
                        vm_page_free_reserve(-1); /* XXX */
                }
                thread->options &= ~TH_OPT_VMPRIV;
        }

        return KERN_SUCCESS;
}


/*
 *      thread_wire:
 *
 *      User-api wrapper for thread_wire_internal()
 */
kern_return_t
thread_wire(
        host_priv_t     host_priv,
        thread_t        thread,
        boolean_t       wired)
{
        return thread_wire_internal(host_priv, thread, wired, NULL);
}


boolean_t
is_vm_privileged(void)
{
        return current_thread()->options & TH_OPT_VMPRIV ? TRUE : FALSE;
}

boolean_t
set_vm_privilege(boolean_t privileged)
{
        boolean_t       was_vmpriv;

        if (current_thread()->options & TH_OPT_VMPRIV) {
                was_vmpriv = TRUE;
        } else {
                was_vmpriv = FALSE;
        }

        if (privileged != FALSE) {
                current_thread()->options |= TH_OPT_VMPRIV;
        } else {
                current_thread()->options &= ~TH_OPT_VMPRIV;
        }

        return was_vmpriv;
}

void
set_thread_rwlock_boost(void)
{
        current_thread()->rwlock_count++;
}

void
clear_thread_rwlock_boost(void)
{
        thread_t thread = current_thread();

        if ((thread->rwlock_count-- == 1) && (thread->sched_flags & TH_SFLAG_RW_PROMOTED)) {
                lck_rw_clear_promotion(thread, 0);
        }
}

/*
 * XXX assuming current thread only, for now...
 */
void
thread_guard_violation(thread_t thread,
    mach_exception_data_type_t code, mach_exception_data_type_t subcode, boolean_t fatal)
{
        assert(thread == current_thread());

        /* Don't set up the AST for kernel threads; this check is needed to ensure
         * that the guard_exc_* fields in the thread structure are set only by the
         * current thread and therefore, don't require a lock.
         */
        if (thread->task == kernel_task) {
                return;
        }

        assert(EXC_GUARD_DECODE_GUARD_TYPE(code));

        /*
         * Use the saved state area of the thread structure
         * to store all info required to handle the AST when
         * returning to userspace. It's possible that there is
         * already a pending guard exception. If it's non-fatal,
         * it can only be over-written by a fatal exception code.
         */
        if (thread->guard_exc_info.code && (thread->guard_exc_fatal || !fatal)) {
                return;
        }

        thread->guard_exc_info.code = code;
        thread->guard_exc_info.subcode = subcode;
        thread->guard_exc_fatal = fatal ? 1 : 0;

        spl_t s = splsched();
        thread_ast_set(thread, AST_GUARD);
        ast_propagate(thread);
        splx(s);
}

/*
 *      guard_ast:
 *
 *      Handle AST_GUARD for a thread. This routine looks at the
 *      state saved in the thread structure to determine the cause
 *      of this exception. Based on this value, it invokes the
 *      appropriate routine which determines other exception related
 *      info and raises the exception.
 */
void
guard_ast(thread_t t)
{
        const mach_exception_data_type_t
            code = t->guard_exc_info.code,
            subcode = t->guard_exc_info.subcode;

        t->guard_exc_info.code = 0;
        t->guard_exc_info.subcode = 0;
        t->guard_exc_fatal = 0;

        switch (EXC_GUARD_DECODE_GUARD_TYPE(code)) {
        case GUARD_TYPE_NONE:
                /* lingering AST_GUARD on the processor? */
                break;
        case GUARD_TYPE_MACH_PORT:
                mach_port_guard_ast(t, code, subcode);
                break;
        case GUARD_TYPE_FD:
                fd_guard_ast(t, code, subcode);
                break;
#if CONFIG_VNGUARD
        case GUARD_TYPE_VN:
                vn_guard_ast(t, code, subcode);
                break;
#endif
        case GUARD_TYPE_VIRT_MEMORY:
                virt_memory_guard_ast(t, code, subcode);
                break;
        default:
                panic("guard_exc_info %llx %llx", code, subcode);
        }
}

static void
thread_cputime_callback(int warning, __unused const void *arg0, __unused const void *arg1)
{
        if (warning == LEDGER_WARNING_ROSE_ABOVE) {
#if CONFIG_TELEMETRY
                /*
                 * This thread is in danger of violating the CPU usage monitor. Enable telemetry
                 * on the entire task so there are micro-stackshots available if and when
                 * EXC_RESOURCE is triggered. We could have chosen to enable micro-stackshots
                 * for this thread only; but now that this task is suspect, knowing what all of
                 * its threads are up to will be useful.
                 */
                telemetry_task_ctl(current_task(), TF_CPUMON_WARNING, 1);
#endif
                return;
        }

#if CONFIG_TELEMETRY
        /*
         * If the balance has dipped below the warning level (LEDGER_WARNING_DIPPED_BELOW) or
         * exceeded the limit, turn telemetry off for the task.
         */
        telemetry_task_ctl(current_task(), TF_CPUMON_WARNING, 0);
#endif

        if (warning == 0) {
                SENDING_NOTIFICATION__THIS_THREAD_IS_CONSUMING_TOO_MUCH_CPU();
        }
}

void __attribute__((noinline))
SENDING_NOTIFICATION__THIS_THREAD_IS_CONSUMING_TOO_MUCH_CPU(void)
{
        int          pid                = 0;
        task_t           task                           = current_task();
        thread_t     thread             = current_thread();
        uint64_t     tid                = thread->thread_id;
        const char       *procname          = "unknown";
        time_value_t thread_total_time  = {0, 0};
        time_value_t thread_system_time;
        time_value_t thread_user_time;
        int          action;
        uint8_t      percentage;
        uint32_t     usage_percent = 0;
        uint32_t     interval_sec;
        uint64_t     interval_ns;
        uint64_t     balance_ns;
        boolean_t        fatal = FALSE;
        boolean_t        send_exc_resource = TRUE; /* in addition to RESOURCE_NOTIFY */
        kern_return_t   kr;

#ifdef EXC_RESOURCE_MONITORS
        mach_exception_data_type_t      code[EXCEPTION_CODE_MAX];
#endif /* EXC_RESOURCE_MONITORS */
        struct ledger_entry_info        lei;

        assert(thread->t_threadledger != LEDGER_NULL);

        /*
         * Extract the fatal bit and suspend the monitor (which clears the bit).
         */
        task_lock(task);
        if (task->rusage_cpu_flags & TASK_RUSECPU_FLAGS_FATAL_CPUMON) {
                fatal = TRUE;
                send_exc_resource = TRUE;
        }
        /* Only one thread can be here at a time.  Whichever makes it through
         *  first will successfully suspend the monitor and proceed to send the
         *  notification.  Other threads will get an error trying to suspend the
         *  monitor and give up on sending the notification.  In the first release,
         *  the monitor won't be resumed for a number of seconds, but we may
         *  eventually need to handle low-latency resume.
         */
        kr = task_suspend_cpumon(task);
        task_unlock(task);
        if (kr == KERN_INVALID_ARGUMENT) {
                return;
        }

#ifdef MACH_BSD
        pid = proc_selfpid();
        if (task->bsd_info != NULL) {
                procname = proc_name_address(task->bsd_info);
        }
#endif

        thread_get_cpulimit(&action, &percentage, &interval_ns);

        interval_sec = (uint32_t)(interval_ns / NSEC_PER_SEC);

        thread_read_times(thread, &thread_user_time, &thread_system_time, NULL);
        time_value_add(&thread_total_time, &thread_user_time);
        time_value_add(&thread_total_time, &thread_system_time);
        ledger_get_entry_info(thread->t_threadledger, thread_ledgers.cpu_time, &lei);

        /* credit/debit/balance/limit are in absolute time units;
         *  the refill info is in nanoseconds. */
        absolutetime_to_nanoseconds(lei.lei_balance, &balance_ns);
        if (lei.lei_last_refill > 0) {
                usage_percent = (uint32_t)((balance_ns * 100ULL) / lei.lei_last_refill);
        }

        /* TODO: show task total runtime (via TASK_ABSOLUTETIME_INFO)? */
        printf("process %s[%d] thread %llu caught burning CPU! It used more than %d%% CPU over %u seconds\n",
            procname, pid, tid, percentage, interval_sec);
        printf("  (actual recent usage: %d%% over ~%llu seconds)\n",
            usage_percent, (lei.lei_last_refill + NSEC_PER_SEC / 2) / NSEC_PER_SEC);
        printf("  Thread lifetime cpu usage %d.%06ds, (%d.%06d user, %d.%06d sys)\n",
            thread_total_time.seconds, thread_total_time.microseconds,
            thread_user_time.seconds, thread_user_time.microseconds,
            thread_system_time.seconds, thread_system_time.microseconds);
        printf("  Ledger balance: %lld; mabs credit: %lld; mabs debit: %lld\n",
            lei.lei_balance, lei.lei_credit, lei.lei_debit);
        printf("  mabs limit: %llu; mabs period: %llu ns; last refill: %llu ns%s.\n",
            lei.lei_limit, lei.lei_refill_period, lei.lei_last_refill,
            (fatal ? " [fatal violation]" : ""));

        /*
         *  For now, send RESOURCE_NOTIFY in parallel with EXC_RESOURCE.  Once
         *  we have logging parity, we will stop sending EXC_RESOURCE (24508922).
         */

        /* RESOURCE_NOTIFY MIG specifies nanoseconds of CPU time */
        lei.lei_balance = balance_ns;
        absolutetime_to_nanoseconds(lei.lei_limit, &lei.lei_limit);
        trace_resource_violation(RMON_CPUUSAGE_VIOLATED, &lei);
        kr = send_resource_violation(send_cpu_usage_violation, task, &lei,
            fatal ? kRNFatalLimitFlag : 0);
        if (kr) {
                printf("send_resource_violation(CPU usage, ...): error %#x\n", kr);
        }

#ifdef EXC_RESOURCE_MONITORS
        if (send_exc_resource) {
                if (disable_exc_resource) {
                        printf("process %s[%d] thread %llu caught burning CPU! "
                            "EXC_RESOURCE%s supressed by a boot-arg\n",
                            procname, pid, tid, fatal ? " (and termination)" : "");
                        return;
                }

                if (audio_active) {
                        printf("process %s[%d] thread %llu caught burning CPU! "
                            "EXC_RESOURCE & termination supressed due to audio playback\n",
                            procname, pid, tid);
                        return;
                }
        }


        if (send_exc_resource) {
                code[0] = code[1] = 0;
                EXC_RESOURCE_ENCODE_TYPE(code[0], RESOURCE_TYPE_CPU);
                if (fatal) {
                        EXC_RESOURCE_ENCODE_FLAVOR(code[0], FLAVOR_CPU_MONITOR_FATAL);
                } else {
                        EXC_RESOURCE_ENCODE_FLAVOR(code[0], FLAVOR_CPU_MONITOR);
                }
                EXC_RESOURCE_CPUMONITOR_ENCODE_INTERVAL(code[0], interval_sec);
                EXC_RESOURCE_CPUMONITOR_ENCODE_PERCENTAGE(code[0], percentage);
                EXC_RESOURCE_CPUMONITOR_ENCODE_PERCENTAGE(code[1], usage_percent);
                exception_triage(EXC_RESOURCE, code, EXCEPTION_CODE_MAX);
        }
#endif /* EXC_RESOURCE_MONITORS */

        if (fatal) {
#if CONFIG_JETSAM
                jetsam_on_ledger_cpulimit_exceeded();
#else
                task_terminate_internal(task);
#endif
        }
}

#if DEVELOPMENT || DEBUG
void __attribute__((noinline))
SENDING_NOTIFICATION__TASK_HAS_TOO_MANY_THREADS(task_t task, int thread_count)
{
        mach_exception_data_type_t code[EXCEPTION_CODE_MAX] = {0};
        int pid = task_pid(task);
        char procname[MAXCOMLEN + 1] = "unknown";

        if (pid == 1) {
                /*
                 * Cannot suspend launchd
                 */
                return;
        }

        proc_name(pid, procname, sizeof(procname));

        if (disable_exc_resource) {
                printf("process %s[%d] crossed thread count high watermark (%d), EXC_RESOURCE "
                    "supressed by a boot-arg. \n", procname, pid, thread_count);
                return;
        }

        if (audio_active) {
                printf("process %s[%d] crossed thread count high watermark (%d), EXC_RESOURCE "
                    "supressed due to audio playback.\n", procname, pid, thread_count);
                return;
        }

        if (exc_via_corpse_forking == 0) {
                printf("process %s[%d] crossed thread count high watermark (%d), EXC_RESOURCE "
                    "supressed due to corpse forking being disabled.\n", procname, pid,
                    thread_count);
                return;
        }

        printf("process %s[%d] crossed thread count high watermark (%d), sending "
            "EXC_RESOURCE\n", procname, pid, thread_count);

        EXC_RESOURCE_ENCODE_TYPE(code[0], RESOURCE_TYPE_THREADS);
        EXC_RESOURCE_ENCODE_FLAVOR(code[0], FLAVOR_THREADS_HIGH_WATERMARK);
        EXC_RESOURCE_THREADS_ENCODE_THREADS(code[0], thread_count);

        task_enqueue_exception_with_corpse(task, EXC_RESOURCE, code, EXCEPTION_CODE_MAX, NULL);
}
#endif /* DEVELOPMENT || DEBUG */

void
thread_update_io_stats(thread_t thread, int size, int io_flags)
{
        int io_tier;

        if (thread->thread_io_stats == NULL || thread->task->task_io_stats == NULL) {
                return;
        }

        if (io_flags & DKIO_READ) {
                UPDATE_IO_STATS(thread->thread_io_stats->disk_reads, size);
                UPDATE_IO_STATS_ATOMIC(thread->task->task_io_stats->disk_reads, size);
        }

        if (io_flags & DKIO_META) {
                UPDATE_IO_STATS(thread->thread_io_stats->metadata, size);
                UPDATE_IO_STATS_ATOMIC(thread->task->task_io_stats->metadata, size);
        }

        if (io_flags & DKIO_PAGING) {
                UPDATE_IO_STATS(thread->thread_io_stats->paging, size);
                UPDATE_IO_STATS_ATOMIC(thread->task->task_io_stats->paging, size);
        }

        io_tier = ((io_flags & DKIO_TIER_MASK) >> DKIO_TIER_SHIFT);
        assert(io_tier < IO_NUM_PRIORITIES);

        UPDATE_IO_STATS(thread->thread_io_stats->io_priority[io_tier], size);
        UPDATE_IO_STATS_ATOMIC(thread->task->task_io_stats->io_priority[io_tier], size);

        /* Update Total I/O Counts */
        UPDATE_IO_STATS(thread->thread_io_stats->total_io, size);
        UPDATE_IO_STATS_ATOMIC(thread->task->task_io_stats->total_io, size);

        if (!(io_flags & DKIO_READ)) {
                DTRACE_IO3(physical_writes, struct task *, thread->task, uint32_t, size, int, io_flags);
                ledger_credit(thread->task->ledger, task_ledgers.physical_writes, size);
        }
}

static void
init_thread_ledgers(void)
{
        ledger_template_t t;
        int idx;

        assert(thread_ledger_template == NULL);

        if ((t = ledger_template_create("Per-thread ledger")) == NULL) {
                panic("couldn't create thread ledger template");
        }

        if ((idx = ledger_entry_add(t, "cpu_time", "sched", "ns")) < 0) {
                panic("couldn't create cpu_time entry for thread ledger template");
        }

        if (ledger_set_callback(t, idx, thread_cputime_callback, NULL, NULL) < 0) {
                panic("couldn't set thread ledger callback for cpu_time entry");
        }

        thread_ledgers.cpu_time = idx;

        ledger_template_complete(t);
        thread_ledger_template = t;
}

/*
 * Returns currently applied CPU usage limit, or 0/0 if none is applied.
 */
int
thread_get_cpulimit(int *action, uint8_t *percentage, uint64_t *interval_ns)
{
        int64_t         abstime = 0;
        uint64_t        limittime = 0;
        thread_t        thread = current_thread();

        *percentage  = 0;
        *interval_ns = 0;
        *action      = 0;

        if (thread->t_threadledger == LEDGER_NULL) {
                /*
                 * This thread has no per-thread ledger, so it can't possibly
                 * have a CPU limit applied.
                 */
                return KERN_SUCCESS;
        }

        ledger_get_period(thread->t_threadledger, thread_ledgers.cpu_time, interval_ns);
        ledger_get_limit(thread->t_threadledger, thread_ledgers.cpu_time, &abstime);

        if ((abstime == LEDGER_LIMIT_INFINITY) || (*interval_ns == 0)) {
                /*
                 * This thread's CPU time ledger has no period or limit; so it
                 * doesn't have a CPU limit applied.
                 */
                return KERN_SUCCESS;
        }

        /*
         * This calculation is the converse to the one in thread_set_cpulimit().
         */
        absolutetime_to_nanoseconds(abstime, &limittime);
        *percentage = (uint8_t)((limittime * 100ULL) / *interval_ns);
        assert(*percentage <= 100);

        if (thread->options & TH_OPT_PROC_CPULIMIT) {
                assert((thread->options & TH_OPT_PRVT_CPULIMIT) == 0);

                *action = THREAD_CPULIMIT_BLOCK;
        } else if (thread->options & TH_OPT_PRVT_CPULIMIT) {
                assert((thread->options & TH_OPT_PROC_CPULIMIT) == 0);

                *action = THREAD_CPULIMIT_EXCEPTION;
        } else {
                *action = THREAD_CPULIMIT_DISABLE;
        }

        return KERN_SUCCESS;
}

/*
 * Set CPU usage limit on a thread.
 *
 * Calling with percentage of 0 will unset the limit for this thread.
 */
int
thread_set_cpulimit(int action, uint8_t percentage, uint64_t interval_ns)
{
        thread_t        thread = current_thread();
        ledger_t        l;
        uint64_t        limittime = 0;
        uint64_t        abstime = 0;

        assert(percentage <= 100);

        if (action == THREAD_CPULIMIT_DISABLE) {
                /*
                 * Remove CPU limit, if any exists.
                 */
                if (thread->t_threadledger != LEDGER_NULL) {
                        l = thread->t_threadledger;
                        ledger_set_limit(l, thread_ledgers.cpu_time, LEDGER_LIMIT_INFINITY, 0);
                        ledger_set_action(l, thread_ledgers.cpu_time, LEDGER_ACTION_IGNORE);
                        thread->options &= ~(TH_OPT_PROC_CPULIMIT | TH_OPT_PRVT_CPULIMIT);
                }

                return 0;
        }

        if (interval_ns < MINIMUM_CPULIMIT_INTERVAL_MS * NSEC_PER_MSEC) {
                return KERN_INVALID_ARGUMENT;
        }

        l = thread->t_threadledger;
        if (l == LEDGER_NULL) {
                /*
                 * This thread doesn't yet have a per-thread ledger; so create one with the CPU time entry active.
                 */
                if ((l = ledger_instantiate(thread_ledger_template, LEDGER_CREATE_INACTIVE_ENTRIES)) == LEDGER_NULL) {
                        return KERN_RESOURCE_SHORTAGE;
                }

                /*
                 * We are the first to create this thread's ledger, so only activate our entry.
                 */
                ledger_entry_setactive(l, thread_ledgers.cpu_time);
                thread->t_threadledger = l;
        }

        /*
         * The limit is specified as a percentage of CPU over an interval in nanoseconds.
         * Calculate the amount of CPU time that the thread needs to consume in order to hit the limit.
         */
        limittime = (interval_ns * percentage) / 100;
        nanoseconds_to_absolutetime(limittime, &abstime);
        ledger_set_limit(l, thread_ledgers.cpu_time, abstime, cpumon_ustackshots_trigger_pct);
        /*
         * Refill the thread's allotted CPU time every interval_ns nanoseconds.
         */
        ledger_set_period(l, thread_ledgers.cpu_time, interval_ns);

        if (action == THREAD_CPULIMIT_EXCEPTION) {
                /*
                 * We don't support programming the CPU usage monitor on a task if any of its
                 * threads have a per-thread blocking CPU limit configured.
                 */
                if (thread->options & TH_OPT_PRVT_CPULIMIT) {
                        panic("CPU usage monitor activated, but blocking thread limit exists");
                }

                /*
                 * Make a note that this thread's CPU limit is being used for the task-wide CPU
                 * usage monitor. We don't have to arm the callback which will trigger the
                 * exception, because that was done for us in ledger_instantiate (because the
                 * ledger template used has a default callback).
                 */
                thread->options |= TH_OPT_PROC_CPULIMIT;
        } else {
                /*
                 * We deliberately override any CPU limit imposed by a task-wide limit (eg
                 * CPU usage monitor).
                 */
                thread->options &= ~TH_OPT_PROC_CPULIMIT;

                thread->options |= TH_OPT_PRVT_CPULIMIT;
                /* The per-thread ledger template by default has a callback for CPU time */
                ledger_disable_callback(l, thread_ledgers.cpu_time);
                ledger_set_action(l, thread_ledgers.cpu_time, LEDGER_ACTION_BLOCK);
        }

        return 0;
}

void
thread_sched_call(
        thread_t                thread,
        sched_call_t    call)
{
        assert((thread->state & TH_WAIT_REPORT) == 0);
        thread->sched_call = call;
}

uint64_t
thread_tid(
        thread_t        thread)
{
        return thread != THREAD_NULL? thread->thread_id: 0;
}

uint16_t
thread_set_tag(thread_t th, uint16_t tag)
{
        return thread_set_tag_internal(th, tag);
}

uint16_t
thread_get_tag(thread_t th)
{
        return thread_get_tag_internal(th);
}

uint64_t
thread_last_run_time(thread_t th)
{
        return th->last_run_time;
}

uint64_t
thread_dispatchqaddr(
        thread_t                thread)
{
        uint64_t        dispatchqueue_addr;
        uint64_t        thread_handle;

        if (thread == THREAD_NULL) {
                return 0;
        }

        thread_handle = thread->machine.cthread_self;
        if (thread_handle == 0) {
                return 0;
        }

        if (thread->inspection == TRUE) {
                dispatchqueue_addr = thread_handle + get_task_dispatchqueue_offset(thread->task);
        } else if (thread->task->bsd_info) {
                dispatchqueue_addr = thread_handle + get_dispatchqueue_offset_from_proc(thread->task->bsd_info);
        } else {
                dispatchqueue_addr = 0;
        }

        return dispatchqueue_addr;
}

uint64_t
thread_rettokern_addr(
        thread_t                thread)
{
        uint64_t        rettokern_addr;
        uint64_t        rettokern_offset;
        uint64_t        thread_handle;

        if (thread == THREAD_NULL) {
                return 0;
        }

        thread_handle = thread->machine.cthread_self;
        if (thread_handle == 0) {
                return 0;
        }

        if (thread->task->bsd_info) {
                rettokern_offset = get_return_to_kernel_offset_from_proc(thread->task->bsd_info);

                /* Return 0 if return to kernel offset is not initialized. */
                if (rettokern_offset == 0) {
                        rettokern_addr = 0;
                } else {
                        rettokern_addr = thread_handle + rettokern_offset;
                }
        } else {
                rettokern_addr = 0;
        }

        return rettokern_addr;
}

/*
 * Export routines to other components for things that are done as macros
 * within the osfmk component.
 */

#undef thread_mtx_lock
void thread_mtx_lock(thread_t thread);
void
thread_mtx_lock(thread_t thread)
{
        lck_mtx_lock(&thread->mutex);
}

#undef thread_mtx_unlock
void thread_mtx_unlock(thread_t thread);
void
thread_mtx_unlock(thread_t thread)
{
        lck_mtx_unlock(&thread->mutex);
}

#undef thread_reference
void thread_reference(thread_t thread);
void
thread_reference(
        thread_t        thread)
{
        if (thread != THREAD_NULL) {
                thread_reference_internal(thread);
        }
}

#undef thread_should_halt

boolean_t
thread_should_halt(
        thread_t                th)
{
        return thread_should_halt_fast(th);
}

/*
 * thread_set_voucher_name - reset the voucher port name bound to this thread
 *
 * Conditions:  nothing locked
 */

kern_return_t
thread_set_voucher_name(mach_port_name_t voucher_name)
{
        thread_t thread = current_thread();
        ipc_voucher_t new_voucher = IPC_VOUCHER_NULL;
        ipc_voucher_t voucher;
        ledger_t bankledger = NULL;
        struct thread_group *banktg = NULL;
        uint32_t persona_id = 0;

        if (MACH_PORT_DEAD == voucher_name) {
                return KERN_INVALID_RIGHT;
        }

        /*
         * agressively convert to voucher reference
         */
        if (MACH_PORT_VALID(voucher_name)) {
                new_voucher = convert_port_name_to_voucher(voucher_name);
                if (IPC_VOUCHER_NULL == new_voucher) {
                        return KERN_INVALID_ARGUMENT;
                }
        }
        bank_get_bank_ledger_thread_group_and_persona(new_voucher, &bankledger, &banktg, &persona_id);

        thread_mtx_lock(thread);
        voucher = thread->ith_voucher;
        thread->ith_voucher_name = voucher_name;
        thread->ith_voucher = new_voucher;
        thread_mtx_unlock(thread);

        bank_swap_thread_bank_ledger(thread, bankledger);
#if CONFIG_THREAD_GROUPS
        thread_group_set_bank(thread, banktg);
#endif /* CONFIG_THREAD_GROUPS */

        KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
            MACHDBG_CODE(DBG_MACH_IPC, MACH_THREAD_SET_VOUCHER) | DBG_FUNC_NONE,
            (uintptr_t)thread_tid(thread),
            (uintptr_t)voucher_name,
            VM_KERNEL_ADDRPERM((uintptr_t)new_voucher),
            persona_id, 0);

        if (IPC_VOUCHER_NULL != voucher) {
                ipc_voucher_release(voucher);
        }

        return KERN_SUCCESS;
}

/*
 *  thread_get_mach_voucher - return a voucher reference for the specified thread voucher
 *
 *  Conditions:  nothing locked
 *
 *  NOTE:       At the moment, there is no distinction between the current and effective
 *              vouchers because we only set them at the thread level currently.
 */
kern_return_t
thread_get_mach_voucher(
        thread_act_t            thread,
        mach_voucher_selector_t __unused which,
        ipc_voucher_t           *voucherp)
{
        ipc_voucher_t           voucher;

        if (THREAD_NULL == thread) {
                return KERN_INVALID_ARGUMENT;
        }

        thread_mtx_lock(thread);
        voucher = thread->ith_voucher;

        if (IPC_VOUCHER_NULL != voucher) {
                ipc_voucher_reference(voucher);
                thread_mtx_unlock(thread);
                *voucherp = voucher;
                return KERN_SUCCESS;
        }

        thread_mtx_unlock(thread);

        *voucherp = IPC_VOUCHER_NULL;
        return KERN_SUCCESS;
}

/*
 *  thread_set_mach_voucher - set a voucher reference for the specified thread voucher
 *
 *  Conditions: callers holds a reference on the voucher.
 *              nothing locked.
 *
 *  We grab another reference to the voucher and bind it to the thread.
 *  The old voucher reference associated with the thread is
 *  discarded.
 */
kern_return_t
thread_set_mach_voucher(
        thread_t                thread,
        ipc_voucher_t           voucher)
{
        ipc_voucher_t old_voucher;
        ledger_t bankledger = NULL;
        struct thread_group *banktg = NULL;
        uint32_t persona_id = 0;

        if (THREAD_NULL == thread) {
                return KERN_INVALID_ARGUMENT;
        }

        bank_get_bank_ledger_thread_group_and_persona(voucher, &bankledger, &banktg, &persona_id);

        thread_mtx_lock(thread);
        /*
         * Once the thread is started, we will look at `ith_voucher` without
         * holding any lock.
         *
         * Setting the voucher hence can only be done by current_thread() or
         * before it started. "started" flips under the thread mutex and must be
         * tested under it too.
         */
        if (thread != current_thread() && thread->started) {
                thread_mtx_unlock(thread);
                return KERN_INVALID_ARGUMENT;
        }

        ipc_voucher_reference(voucher);
        old_voucher = thread->ith_voucher;
        thread->ith_voucher = voucher;
        thread->ith_voucher_name = MACH_PORT_NULL;
        thread_mtx_unlock(thread);

        bank_swap_thread_bank_ledger(thread, bankledger);
#if CONFIG_THREAD_GROUPS
        thread_group_set_bank(thread, banktg);
#endif /* CONFIG_THREAD_GROUPS */

        KERNEL_DEBUG_CONSTANT_IST(KDEBUG_TRACE,
            MACHDBG_CODE(DBG_MACH_IPC, MACH_THREAD_SET_VOUCHER) | DBG_FUNC_NONE,
            (uintptr_t)thread_tid(thread),
            (uintptr_t)MACH_PORT_NULL,
            VM_KERNEL_ADDRPERM((uintptr_t)voucher),
            persona_id, 0);

        ipc_voucher_release(old_voucher);

        return KERN_SUCCESS;
}

/*
 *  thread_swap_mach_voucher - swap a voucher reference for the specified thread voucher
 *
 *  Conditions: callers holds a reference on the new and presumed old voucher(s).
 *              nothing locked.
 *
 *  This function is no longer supported.
 */
kern_return_t
thread_swap_mach_voucher(
        __unused thread_t               thread,
        __unused ipc_voucher_t          new_voucher,
        ipc_voucher_t                   *in_out_old_voucher)
{
        /*
         * Currently this function is only called from a MIG generated
         * routine which doesn't release the reference on the voucher
         * addressed by in_out_old_voucher. To avoid leaking this reference,
         * a call to release it has been added here.
         */
        ipc_voucher_release(*in_out_old_voucher);
        return KERN_NOT_SUPPORTED;
}

/*
 *  thread_get_current_voucher_origin_pid - get the pid of the originator of the current voucher.
 */
kern_return_t
thread_get_current_voucher_origin_pid(
        int32_t      *pid)
{
        uint32_t buf_size;
        kern_return_t kr;
        thread_t thread = current_thread();

        buf_size = sizeof(*pid);
        kr = mach_voucher_attr_command(thread->ith_voucher,
            MACH_VOUCHER_ATTR_KEY_BANK,
            BANK_ORIGINATOR_PID,
            NULL,
            0,
            (mach_voucher_attr_content_t)pid,
            &buf_size);

        return kr;
}

#if CONFIG_THREAD_GROUPS
/*
 * Returns the current thread's voucher-carried thread group
 *
 * Reference is borrowed from this being the current voucher, so it does NOT
 * return a reference to the group.
 */
struct thread_group *
thread_get_current_voucher_thread_group(thread_t thread)
{
        assert(thread == current_thread());

        if (thread->ith_voucher == NULL) {
                return NULL;
        }

        ledger_t bankledger = NULL;
        struct thread_group *banktg = NULL;

        bank_get_bank_ledger_thread_group_and_persona(thread->ith_voucher, &bankledger, &banktg, NULL);

        return banktg;
}

#endif /* CONFIG_THREAD_GROUPS */

boolean_t
thread_has_thread_name(thread_t th)
{
        if ((th) && (th->uthread)) {
                return bsd_hasthreadname(th->uthread);
        }

        /*
         * This is an odd case; clients may set the thread name based on the lack of
         * a name, but in this context there is no uthread to attach the name to.
         */
        return FALSE;
}

void
thread_set_thread_name(thread_t th, const char* name)
{
        if ((th) && (th->uthread) && name) {
                bsd_setthreadname(th->uthread, name);
        }
}

void
thread_get_thread_name(thread_t th, char* name)
{
        if (!name) {
                return;
        }
        if ((th) && (th->uthread)) {
                bsd_getthreadname(th->uthread, name);
        } else {
                name[0] = '\0';
        }
}

void
thread_set_honor_qlimit(thread_t thread)
{
        thread->options |= TH_OPT_HONOR_QLIMIT;
}

void
thread_clear_honor_qlimit(thread_t thread)
{
        thread->options &= (~TH_OPT_HONOR_QLIMIT);
}

/*
 * thread_enable_send_importance - set/clear the SEND_IMPORTANCE thread option bit.
 */
void
thread_enable_send_importance(thread_t thread, boolean_t enable)
{
        if (enable == TRUE) {
                thread->options |= TH_OPT_SEND_IMPORTANCE;
        } else {
                thread->options &= ~TH_OPT_SEND_IMPORTANCE;
        }
}

/*
 * thread_set_allocation_name - .
 */

kern_allocation_name_t
thread_set_allocation_name(kern_allocation_name_t new_name)
{
        kern_allocation_name_t ret;
        thread_kernel_state_t kstate = thread_get_kernel_state(current_thread());
        ret = kstate->allocation_name;
        // fifo
        if (!new_name || !kstate->allocation_name) {
                kstate->allocation_name = new_name;
        }
        return ret;
}

void *
thread_iokit_tls_get(uint32_t index)
{
        assert(index < THREAD_SAVE_IOKIT_TLS_COUNT);
        return current_thread()->saved.iokit.tls[index];
}

void
thread_iokit_tls_set(uint32_t index, void * data)
{
        assert(index < THREAD_SAVE_IOKIT_TLS_COUNT);
        current_thread()->saved.iokit.tls[index] = data;
}

uint64_t
thread_get_last_wait_duration(thread_t thread)
{
        return thread->last_made_runnable_time - thread->last_run_time;
}

integer_t
thread_kern_get_pri(thread_t thr)
{
        return thr->base_pri;
}

void
thread_kern_set_pri(thread_t thr, integer_t pri)
{
        sched_set_kernel_thread_priority(thr, pri);
}

integer_t
thread_kern_get_kernel_maxpri(void)
{
        return MAXPRI_KERNEL;
}
/*
 *      thread_port_with_flavor_notify
 *
 *      Called whenever the Mach port system detects no-senders on
 *      the thread inspect or read port. These ports are allocated lazily and
 *      should be deallocated here when there are no senders remaining.
 */
void
thread_port_with_flavor_notify(mach_msg_header_t *msg)
{
        mach_no_senders_notification_t *notification = (void *)msg;
        ipc_port_t port = notification->not_header.msgh_remote_port;
        thread_t thread;
        mach_thread_flavor_t flavor;
        ipc_kobject_type_t kotype;

        ip_lock(port);
        if (port->ip_srights > 0) {
                ip_unlock(port);
                return;
        }
        thread = (thread_t)ipc_kobject_get(port);
        kotype = ip_kotype(port);
        if (thread != THREAD_NULL) {
                assert((IKOT_THREAD_READ == kotype) || (IKOT_THREAD_INSPECT == kotype));
                thread_reference_internal(thread);
        }
        ip_unlock(port);

        if (thread == THREAD_NULL) {
                /* The thread is exiting or disabled; it will eventually deallocate the port */
                return;
        }

        if (kotype == IKOT_THREAD_READ) {
                flavor = THREAD_FLAVOR_READ;
        } else {
                flavor = THREAD_FLAVOR_INSPECT;
        }

        thread_mtx_lock(thread);
        ip_lock(port);
        /*
         * If the port is no longer active, then ipc_thread_terminate() ran
         * and destroyed the kobject already. Just deallocate the task
         * ref we took and go away.
         *
         * It is also possible that several nsrequests are in flight,
         * only one shall NULL-out the port entry, and this is the one
         * that gets to dealloc the port.
         *
         * Check for a stale no-senders notification. A call to any function
         * that vends out send rights to this port could resurrect it between
         * this notification being generated and actually being handled here.
         */
        if (!ip_active(port) ||
            thread->ith_thread_ports[flavor] != port ||
            port->ip_srights > 0) {
                ip_unlock(port);
                thread_mtx_unlock(thread);
                thread_deallocate(thread);
                return;
        }

        assert(thread->ith_thread_ports[flavor] == port);
        thread->ith_thread_ports[flavor] = IP_NULL;
        ipc_kobject_set_atomically(port, IKO_NULL, IKOT_NONE);
        ip_unlock(port);
        thread_mtx_unlock(thread);
        thread_deallocate(thread);

        ipc_port_dealloc_kernel(port);
}

/*
 * The 'thread_region_page_shift' is used by footprint
 * to specify the page size that it will use to
 * accomplish its accounting work on the task being
 * inspected. Since footprint uses a thread for each
 * task that it works on, we need to keep the page_shift
 * on a per-thread basis.
 */

int
thread_self_region_page_shift(void)
{
        /*
         * Return the page shift that this thread
         * would like to use for its accounting work.
         */
        return current_thread()->thread_region_page_shift;
}

void
thread_self_region_page_shift_set(
        int pgshift)
{
        /*
         * Set the page shift that this thread
         * would like to use for its accounting work
         * when dealing with a task.
         */
        current_thread()->thread_region_page_shift = pgshift;
}

#if CONFIG_DTRACE
uint32_t
dtrace_get_thread_predcache(thread_t thread)
{
        if (thread != THREAD_NULL) {
                return thread->t_dtrace_predcache;
        } else {
                return 0;
        }
}

int64_t
dtrace_get_thread_vtime(thread_t thread)
{
        if (thread != THREAD_NULL) {
                return thread->t_dtrace_vtime;
        } else {
                return 0;
        }
}

int
dtrace_get_thread_last_cpu_id(thread_t thread)
{
        if ((thread != THREAD_NULL) && (thread->last_processor != PROCESSOR_NULL)) {
                return thread->last_processor->cpu_id;
        } else {
                return -1;
        }
}

int64_t
dtrace_get_thread_tracing(thread_t thread)
{
        if (thread != THREAD_NULL) {
                return thread->t_dtrace_tracing;
        } else {
                return 0;
        }
}

uint16_t
dtrace_get_thread_inprobe(thread_t thread)
{
        if (thread != THREAD_NULL) {
                return thread->t_dtrace_inprobe;
        } else {
                return 0;
        }
}

vm_offset_t
dtrace_get_kernel_stack(thread_t thread)
{
        if (thread != THREAD_NULL) {
                return thread->kernel_stack;
        } else {
                return 0;
        }
}

#if KASAN
struct kasan_thread_data *
kasan_get_thread_data(thread_t thread)
{
        return &thread->kasan_data;
}
#endif

#if CONFIG_KSANCOV
void **
__sanitizer_get_thread_data(thread_t thread)
{
        return &thread->ksancov_data;
}
#endif

int64_t
dtrace_calc_thread_recent_vtime(thread_t thread)
{
        if (thread != THREAD_NULL) {
                processor_t             processor = current_processor();
                uint64_t                                abstime = mach_absolute_time();
                timer_t                                 timer;

                timer = processor->thread_timer;

                return timer_grab(&(thread->system_timer)) + timer_grab(&(thread->user_timer)) +
                       (abstime - timer->tstamp);          /* XXX need interrupts off to prevent missed time? */
        } else {
                return 0;
        }
}

void
dtrace_set_thread_predcache(thread_t thread, uint32_t predcache)
{
        if (thread != THREAD_NULL) {
                thread->t_dtrace_predcache = predcache;
        }
}

void
dtrace_set_thread_vtime(thread_t thread, int64_t vtime)
{
        if (thread != THREAD_NULL) {
                thread->t_dtrace_vtime = vtime;
        }
}

void
dtrace_set_thread_tracing(thread_t thread, int64_t accum)
{
        if (thread != THREAD_NULL) {
                thread->t_dtrace_tracing = accum;
        }
}

void
dtrace_set_thread_inprobe(thread_t thread, uint16_t inprobe)
{
        if (thread != THREAD_NULL) {
                thread->t_dtrace_inprobe = inprobe;
        }
}

vm_offset_t
dtrace_set_thread_recover(thread_t thread, vm_offset_t recover)
{
        vm_offset_t prev = 0;

        if (thread != THREAD_NULL) {
                prev = thread->recover;
                thread->recover = recover;
        }
        return prev;
}

vm_offset_t
dtrace_sign_and_set_thread_recover(thread_t thread, vm_offset_t recover)
{
#if defined(HAS_APPLE_PAC)
        return dtrace_set_thread_recover(thread,
                   (vm_address_t)ptrauth_sign_unauthenticated((void *)recover,
                   ptrauth_key_function_pointer,
                   ptrauth_blend_discriminator(&thread->recover, PAC_DISCRIMINATOR_RECOVER)));
#else /* defined(HAS_APPLE_PAC) */
        return dtrace_set_thread_recover(thread, recover);
#endif /* defined(HAS_APPLE_PAC) */
}

void
dtrace_thread_bootstrap(void)
{
        task_t task = current_task();

        if (task->thread_count == 1) {
                thread_t thread = current_thread();
                if (thread->t_dtrace_flags & TH_DTRACE_EXECSUCCESS) {
                        thread->t_dtrace_flags &= ~TH_DTRACE_EXECSUCCESS;
                        DTRACE_PROC(exec__success);
                        KDBG(BSDDBG_CODE(DBG_BSD_PROC, BSD_PROC_EXEC),
                            task_pid(task));
                }
                DTRACE_PROC(start);
        }
        DTRACE_PROC(lwp__start);
}

void
dtrace_thread_didexec(thread_t thread)
{
        thread->t_dtrace_flags |= TH_DTRACE_EXECSUCCESS;
}
#endif /* CONFIG_DTRACE */