/*
 * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * @OSF_FREE_COPYRIGHT@
 */
/*
 * Copyright (c) 1993 The University of Utah and
 * the Center for Software Science (CSS).  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 CSS ALLOW FREE USE OF THIS SOFTWARE IN ITS "AS
 * IS" CONDITION.  THE UNIVERSITY OF UTAH AND CSS DISCLAIM ANY LIABILITY OF
 * ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * CSS requests users of this software to return to css-dist@cs.utah.edu any
 * improvements that they make and grant CSS redistribution rights.
 *
 *      Author: Bryan Ford, University of Utah CSS
 *
 *      Thread management routines
 */
#include <mach/mach_types.h>
#include <mach/kern_return.h>
#include <mach/alert.h>
#include <mach_prof.h>
#include <mach/rpc.h>
#include <mach/thread_act_server.h>

#include <kern/kern_types.h>
#include <kern/ast.h>
#include <kern/mach_param.h>
#include <kern/zalloc.h>
#include <kern/thread.h>
#include <kern/task.h>
#include <kern/sched_prim.h>
#include <kern/misc_protos.h>
#include <kern/assert.h>
#include <kern/exception.h>
#include <kern/ipc_mig.h>
#include <kern/ipc_tt.h>
#include <kern/profile.h>
#include <kern/machine.h>
#include <kern/spl.h>
#include <kern/syscall_subr.h>
#include <kern/sync_lock.h>
#include <kern/processor.h>
#include <kern/timer.h>
#include <mach_prof.h>
#include <mach/rpc.h>

void                    act_abort(thread_t);
void                    act_set_apc(thread_t);
void                    install_special_handler_locked(thread_t);
void                    special_handler_continue(void);

/*
 * Internal routine to terminate a thread.
 * Sometimes called with task already locked.
 */
kern_return_t
thread_terminate_internal(
        thread_t                        thread)
{
        kern_return_t           result = KERN_SUCCESS;

        thread_mtx_lock(thread);

        if (thread->active) {
                thread->active = FALSE;

                act_abort(thread);

                if (thread->started)
                        clear_wait(thread, THREAD_INTERRUPTED);
                else {
                        clear_wait(thread, THREAD_AWAKENED);
                        thread->started = TRUE;
                }
        }
        else
                result = KERN_TERMINATED;

        thread_mtx_unlock(thread);

        if (thread != current_thread() && result == KERN_SUCCESS)
                thread_wait(thread);

        return (result);
}

/*
 * Terminate a thread.
 */
kern_return_t
thread_terminate(
        thread_t                thread)
{
        kern_return_t   result;

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

        if (    thread->task == kernel_task             &&
                        thread != current_thread()                      )
                return (KERN_FAILURE);

        result = thread_terminate_internal(thread);

        /*
         * If a kernel thread is terminating itself, force an AST here.
         * Kernel threads don't normally pass through the AST checking
         * code - and all threads finish their own termination in the
         * special handler APC.
         */
        if (thread->task == kernel_task) {
                ml_set_interrupts_enabled(FALSE);
                ast_taken(AST_APC, TRUE);
                panic("thread_terminate");
        }

        return (result);
}

/*
 * Suspend execution of the specified thread.
 * This is a recursive-style suspension of the thread, a count of
 * suspends is maintained.
 *
 * Called with thread mutex held.
 */
void
thread_hold(
        register thread_t       thread)
{
        if (thread->suspend_count++ == 0) {
                install_special_handler(thread);
                if (thread->started)
                        thread_wakeup_one(&thread->suspend_count);
        }
}

/*
 * Decrement internal suspension count, setting thread
 * runnable when count falls to zero.
 *
 * Called with thread mutex held.
 */
void
thread_release(
        register thread_t       thread)
{
        if (    thread->suspend_count > 0               &&
                        --thread->suspend_count == 0    ) {
                if (thread->started)
                        thread_wakeup_one(&thread->suspend_count);
                else {
                        clear_wait(thread, THREAD_AWAKENED);
                        thread->started = TRUE;
                }
        }
}

kern_return_t
thread_suspend(
        register thread_t       thread)
{
        thread_t                        self = current_thread();
        kern_return_t           result = KERN_SUCCESS;

        if (thread == THREAD_NULL || thread->task == kernel_task)
                return (KERN_INVALID_ARGUMENT);

        thread_mtx_lock(thread);

        if (thread->active) {
                if (    thread->user_stop_count++ == 0          &&
                                thread->suspend_count++ == 0            ) {
                        install_special_handler(thread);
                        if (thread != self)
                                thread_wakeup_one(&thread->suspend_count);
                }
        }
        else
                result = KERN_TERMINATED;

        thread_mtx_unlock(thread);

        if (thread != self && result == KERN_SUCCESS)
                thread_wait(thread);

        return (result);
}

kern_return_t
thread_resume(
        register thread_t       thread)
{
        kern_return_t           result = KERN_SUCCESS;

        if (thread == THREAD_NULL || thread->task == kernel_task)
                return (KERN_INVALID_ARGUMENT);

        thread_mtx_lock(thread);

        if (thread->active) {
                if (thread->user_stop_count > 0) {
                        if (    --thread->user_stop_count == 0          &&
                                        --thread->suspend_count == 0            ) {
                                if (thread->started)
                                        thread_wakeup_one(&thread->suspend_count);
                                else {
                                        clear_wait(thread, THREAD_AWAKENED);
                                        thread->started = TRUE;
                                }
                        }
                }
                else
                        result = KERN_FAILURE;
        }
        else
                result = KERN_TERMINATED;

        thread_mtx_unlock(thread);

        return (result);
}

/*
 *      thread_depress_abort:
 *
 *      Prematurely abort priority depression if there is one.
 */
kern_return_t
thread_depress_abort(
        register thread_t       thread)
{
        kern_return_t           result;

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

    thread_mtx_lock(thread);

        if (thread->active)
                result = thread_depress_abort_internal(thread);
        else
                result = KERN_TERMINATED;

    thread_mtx_unlock(thread);

        return (result);
}


/*
 * Indicate that the activation should run its
 * special handler to detect a condition.
 *
 * Called with thread mutex held.
 */
void
act_abort(
        thread_t        thread)
{
        spl_t           s = splsched();

        thread_lock(thread);

        if (!(thread->state & TH_ABORT)) {
                thread->state |= TH_ABORT;
                install_special_handler_locked(thread);
        }
        else
                thread->state &= ~TH_ABORT_SAFELY;

        thread_unlock(thread);
        splx(s);
}
        
kern_return_t
thread_abort(
        register thread_t       thread)
{
        kern_return_t   result = KERN_SUCCESS;

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

        thread_mtx_lock(thread);

        if (thread->active) {
                act_abort(thread);
                clear_wait(thread, THREAD_INTERRUPTED);
        }
        else
                result = KERN_TERMINATED;

        thread_mtx_unlock(thread);

        return (result);
}

kern_return_t
thread_abort_safely(
        thread_t                thread)
{
        kern_return_t   result = KERN_SUCCESS;

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

        thread_mtx_lock(thread);

        if (thread->active) {
                spl_t           s = splsched();

                thread_lock(thread);
                if (!thread->at_safe_point ||
                        clear_wait_internal(thread, THREAD_INTERRUPTED) != KERN_SUCCESS) {
                        if (!(thread->state & TH_ABORT)) {
                                thread->state |= (TH_ABORT|TH_ABORT_SAFELY);
                                install_special_handler_locked(thread);
                        }
                }
                thread_unlock(thread);
                splx(s);
        }
        else
                result = KERN_TERMINATED;
                
        thread_mtx_unlock(thread);

        return (result);
}

/*** backward compatibility hacks ***/
#include <mach/thread_info.h>
#include <mach/thread_special_ports.h>
#include <ipc/ipc_port.h>

kern_return_t
thread_info(
        thread_t                                thread,
        thread_flavor_t                 flavor,
        thread_info_t                   thread_info_out,
        mach_msg_type_number_t  *thread_info_count)
{
        kern_return_t                   result;

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

        thread_mtx_lock(thread);

        if (thread->active)
                result = thread_info_internal(
                                                thread, flavor, thread_info_out, thread_info_count);
        else
                result = KERN_TERMINATED;

        thread_mtx_unlock(thread);

        return (result);
}

kern_return_t
thread_get_state(
        register thread_t               thread,
        int                                             flavor,
        thread_state_t                  state,                  /* pointer to OUT array */
        mach_msg_type_number_t  *state_count)   /*IN/OUT*/
{
        kern_return_t           result = KERN_SUCCESS;

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

        thread_mtx_lock(thread);

        if (thread->active) {
                if (thread != current_thread()) {
                        thread_hold(thread);

                        thread_mtx_unlock(thread);

                        if (thread_stop(thread)) {
                                thread_mtx_lock(thread);
                                result = machine_thread_get_state(
                                                                                thread, flavor, state, state_count);
                                thread_unstop(thread);
                        }
                        else {
                                thread_mtx_lock(thread);
                                result = KERN_ABORTED;
                        }

                        thread_release(thread);
                }
                else
                        result = machine_thread_get_state(
                                                                        thread, flavor, state, state_count);
        }
        else
                result = KERN_TERMINATED;

        thread_mtx_unlock(thread);

        return (result);
}

/*
 *      Change thread's machine-dependent state.  Called with nothing
 *      locked.  Returns same way.
 */
kern_return_t
thread_set_state(
        register thread_t               thread,
        int                                             flavor,
        thread_state_t                  state,
        mach_msg_type_number_t  state_count)
{
        kern_return_t           result = KERN_SUCCESS;

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

        thread_mtx_lock(thread);

        if (thread->active) {
                if (thread != current_thread()) {
                        thread_hold(thread);

                        thread_mtx_unlock(thread);

                        if (thread_stop(thread)) {
                                thread_mtx_lock(thread);
                                result = machine_thread_set_state(
                                                                                thread, flavor, state, state_count);
                                thread_unstop(thread);
                        }
                        else {
                                thread_mtx_lock(thread);
                                result = KERN_ABORTED;
                        }

                        thread_release(thread);
                }
                else
                        result = machine_thread_set_state(
                                                                        thread, flavor, state, state_count);
        }
        else
                result = KERN_TERMINATED;

        thread_mtx_unlock(thread);

        return (result);
}
 
 
/*
 * Kernel-internal "thread" interfaces used outside this file:
 */

/* Initialize (or re-initialize) a thread state.  Called from execve
 * with nothing locked, returns same way.
 */
kern_return_t
thread_state_initialize(
        register thread_t               thread)
{
        kern_return_t           result = KERN_SUCCESS;

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

        thread_mtx_lock(thread);

        if (thread->active) {
                if (thread != current_thread()) {
                        thread_hold(thread);

                        thread_mtx_unlock(thread);

                        if (thread_stop(thread)) {
                                thread_mtx_lock(thread);
                                result = machine_thread_state_initialize( thread );
                                thread_unstop(thread);
                        }
                        else {
                                thread_mtx_lock(thread);
                                result = KERN_ABORTED;
                        }

                        thread_release(thread);
                }
                else
            result = machine_thread_state_initialize( thread );
        }
        else
                result = KERN_TERMINATED;

        thread_mtx_unlock(thread);

        return (result);
}


kern_return_t
thread_dup(
        register thread_t       target)
{
        thread_t                        self = current_thread();
        kern_return_t           result = KERN_SUCCESS;

        if (target == THREAD_NULL || target == self)
                return (KERN_INVALID_ARGUMENT);

        thread_mtx_lock(target);

        if (target->active) {
                thread_hold(target);

                thread_mtx_unlock(target);

                if (thread_stop(target)) {
                        thread_mtx_lock(target);
                        result = machine_thread_dup(self, target);
                        thread_unstop(target);
                }
                else {
                        thread_mtx_lock(target);
                        result = KERN_ABORTED;
                }

                thread_release(target);
        }
        else
                result = KERN_TERMINATED;

        thread_mtx_unlock(target);

        return (result);
}


/*
 *      thread_setstatus:
 *
 *      Set the status of the specified thread.
 *      Called with (and returns with) no locks held.
 */
kern_return_t
thread_setstatus(
        register thread_t               thread,
        int                                             flavor,
        thread_state_t                  tstate,
        mach_msg_type_number_t  count)
{

        return (thread_set_state(thread, flavor, tstate, count));
}

/*
 *      thread_getstatus:
 *
 *      Get the status of the specified thread.
 */
kern_return_t
thread_getstatus(
        register thread_t               thread,
        int                                             flavor,
        thread_state_t                  tstate,
        mach_msg_type_number_t  *count)
{
        return (thread_get_state(thread, flavor, tstate, count));
}

/*
 * install_special_handler:
 *
 *      Install the special returnhandler that handles suspension and
 *      termination, if it hasn't been installed already.
 *
 *      Called with the thread mutex held.
 */
void
install_special_handler(
        thread_t                thread)
{
        spl_t           s = splsched();

        thread_lock(thread);
        install_special_handler_locked(thread);
        thread_unlock(thread);
        splx(s);
}

/*
 * install_special_handler_locked:
 *
 *      Do the work of installing the special_handler.
 *
 *      Called with the thread mutex and scheduling lock held.
 */
void
install_special_handler_locked(
        thread_t                                thread)
{
        ReturnHandler   **rh;

        /* The work handler must always be the last ReturnHandler on the list,
           because it can do tricky things like detach the thr_act.  */
        for (rh = &thread->handlers; *rh; rh = &(*rh)->next)
                continue;

        if (rh != &thread->special_handler.next)
                *rh = &thread->special_handler;

        /*
         * Temporarily undepress, so target has
         * a chance to do locking required to
         * block itself in special_handler().
         */
        if (thread->sched_mode & TH_MODE_ISDEPRESSED)
                compute_priority(thread, TRUE);

        thread_ast_set(thread, AST_APC);

        if (thread == current_thread())
                ast_propagate(thread->ast);
        else {
                processor_t             processor = thread->last_processor;

                if (    processor != PROCESSOR_NULL                                     &&
                                processor->state == PROCESSOR_RUNNING           &&
                                processor->active_thread == thread                      )
                        cause_ast_check(processor);
        }
}

/*
 * Activation control support routines internal to this file:
 */

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

        thread_ast_clear(thread, AST_APC);
        spllo();

        for (;;) {
                ReturnHandler   *rh;

                thread_mtx_lock(thread);

                (void)splsched();
                thread_lock(thread);

                rh = thread->handlers;
                if (rh != NULL) {
                        thread->handlers = rh->next;

                        thread_unlock(thread);
                        spllo();

                        thread_mtx_unlock(thread);

                        /* Execute it */
                        (*rh->handler)(rh, thread);
                }
                else
                        break;
        }

        thread_unlock(thread);
        spllo();

        thread_mtx_unlock(thread);
}

/*
 * special_handler_continue
 *
 * Continuation routine for the special handler blocks.  It checks
 * to see whether there has been any new suspensions.  If so, it
 * installs the special handler again.  Otherwise, it checks to see
 * if the current depression needs to be re-instated (it may have
 * been temporarily removed in order to get to this point in a hurry).
 */
void
special_handler_continue(void)
{
        thread_t                thread = current_thread();

        thread_mtx_lock(thread);

        if (thread->suspend_count > 0)
                install_special_handler(thread);
        else {
                spl_t                   s = splsched();

                thread_lock(thread);
                if (thread->sched_mode & TH_MODE_ISDEPRESSED) {
                        processor_t             myprocessor = thread->last_processor;

                        thread->sched_pri = DEPRESSPRI;
                        myprocessor->current_pri = thread->sched_pri;
                        thread->sched_mode &= ~TH_MODE_PREEMPT;
                }
                thread_unlock(thread);
                splx(s);
        }

        thread_mtx_unlock(thread);

        thread_exception_return();
        /*NOTREACHED*/
}

/*
 * special_handler      - handles suspension, termination.  Called
 * with nothing locked.  Returns (if it returns) the same way.
 */
void
special_handler(
        __unused ReturnHandler  *rh,
        thread_t                                thread)
{
        spl_t           s;

        thread_mtx_lock(thread);

        s = splsched();
        thread_lock(thread);
        thread->state &= ~(TH_ABORT|TH_ABORT_SAFELY);   /* clear any aborts */
        thread_unlock(thread);
        splx(s);

        /*
         * If we're suspended, go to sleep and wait for someone to wake us up.
         */
        if (thread->active) {
                if (thread->suspend_count > 0) {
                        if (thread->handlers == NULL) {
                                assert_wait(&thread->suspend_count, THREAD_ABORTSAFE);
                                thread_mtx_unlock(thread);
                                thread_block((thread_continue_t)special_handler_continue);
                                /*NOTREACHED*/
                        }

                        thread_mtx_unlock(thread);

                        special_handler_continue();
                        /*NOTREACHED*/
                }
        }
        else {
                thread_mtx_unlock(thread);

                thread_terminate_self();
                /*NOTREACHED*/
        }

        thread_mtx_unlock(thread);
}

kern_return_t
act_set_state(
        thread_t                                thread,
        int                                             flavor,
        thread_state_t                  state,
        mach_msg_type_number_t  count)
{
    if (thread == current_thread())
            return (KERN_INVALID_ARGUMENT);

    return (thread_set_state(thread, flavor, state, count));
    
}

kern_return_t
act_get_state(
        thread_t                                thread,
        int                                             flavor,
        thread_state_t                  state,
        mach_msg_type_number_t  *count)
{
    if (thread == current_thread())
            return (KERN_INVALID_ARGUMENT);

    return (thread_get_state(thread, flavor, state, count));
}

void
act_set_astbsd(
        thread_t        thread)
{
        spl_t           s = splsched();
        
        if (thread == current_thread()) {
                thread_ast_set(thread, AST_BSD);
                ast_propagate(thread->ast);
        }
        else {
                processor_t             processor;

                thread_lock(thread);
                thread_ast_set(thread, AST_BSD);
                processor = thread->last_processor;
                if (    processor != PROCESSOR_NULL                                     &&
                                processor->state == PROCESSOR_RUNNING           &&
                                processor->active_thread == thread                      )
                        cause_ast_check(processor);
                thread_unlock(thread);
        }
        
        splx(s);
}

void
act_set_apc(
        thread_t        thread)
{
        spl_t           s = splsched();
        
        if (thread == current_thread()) {
                thread_ast_set(thread, AST_APC);
                ast_propagate(thread->ast);
        }
        else {
                processor_t             processor;

                thread_lock(thread);
                thread_ast_set(thread, AST_APC);
                processor = thread->last_processor;
                if (    processor != PROCESSOR_NULL                                     &&
                                processor->state == PROCESSOR_RUNNING           &&
                                processor->active_thread == thread                      )
                        cause_ast_check(processor);
                thread_unlock(thread);
        }
        
        splx(s);
}