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/*

 * Copyright (C) 2001-2004 Jakub Jermar

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - Redistributions in binary form must reproduce the above copyright

 *   notice, this list of conditions and the following disclaimer in the

 *   documentation and/or other materials provided with the distribution.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

/**

 * @file    task.c

 * @brief   Task management.

 */

#include <main/uinit.h>

#include <proc/thread.h>

#include <proc/task.h>

#include <proc/uarg.h>

#include <mm/as.h>

#include <mm/slab.h>

#include <synch/spinlock.h>

#include <arch.h>

#include <panic.h>

#include <adt/btree.h>

#include <adt/list.h>

#include <ipc/ipc.h>

#include <security/cap.h>

#include <memstr.h>

#include <print.h>

#include <elf.h>

#include <errno.h>

#include <syscall/copy.h>

#include <console/klog.h>

#ifndef LOADED_PROG_STACK_PAGES_NO

#define LOADED_PROG_STACK_PAGES_NO 1

#endif

/** Spinlock protecting the tasks_btree B+tree. */

SPINLOCK_INITIALIZE(tasks_lock);

/** B+tree of active tasks.

 *

 * The task is guaranteed to exist after it was found in the tasks_btree as long as:

 * @li the tasks_lock is held,

 * @li the task's lock is held when task's lock is acquired before releasing tasks_lock or

 * @li the task's refcount is grater than 0

 *

 */

btree_t tasks_btree;

static task_id_t task_counter = 0;

static void ktaskclnp(void *arg);

static void ktaskgc(void *arg);

/** Initialize tasks

 *

 * Initialize kernel tasks support.

 *

 */

void task_init(void)

{

    TASK = NULL;

    btree_create(&tasks_btree);

}

/** Create new task

 *

 * Create new task with no threads.

 *

 * @param as Task's address space.

 * @param name Symbolic name.

 *

 * @return New task's structure

 *

 */

task_t *task_create(as_t *as, char *name)

{

    ipl_t ipl;

    task_t *ta;

    int i;

    ta = (task_t *) malloc(sizeof(task_t), 0);

    task_create_arch(ta);

    spinlock_initialize(&ta->lock, "task_ta_lock");

    list_initialize(&ta->th_head);

    ta->as = as;

    ta->name = name;

    ta->main_thread = NULL;

    ta->refcount = 0;

    ta->capabilities = 0;

    ta->accept_new_threads = true;

    ipc_answerbox_init(&ta->answerbox);

    for (i=0; i < IPC_MAX_PHONES;i++)

        ipc_phone_init(&ta->phones[i]);

    if (ipc_phone_0)

        ipc_phone_connect(&ta->phones[0], ipc_phone_0);

    atomic_set(&ta->active_calls, 0);

    mutex_initialize(&ta->futexes_lock);

    btree_create(&ta->futexes);

    ipl = interrupts_disable();

    /*

     * Increment address space reference count.

     * TODO: Reconsider the locking scheme.

     */

    mutex_lock(&as->lock);

    as->refcount++;

    mutex_unlock(&as->lock);

    spinlock_lock(&tasks_lock);

    ta->taskid = ++task_counter;

    btree_insert(&tasks_btree, (btree_key_t) ta->taskid, (void *) ta, NULL);

    spinlock_unlock(&tasks_lock);

    interrupts_restore(ipl);

    return ta;

}

/** Destroy task.

 *

 * @param t Task to be destroyed.

 */

void task_destroy(task_t *t)

{

    task_destroy_arch(t);

    btree_destroy(&t->futexes);

    mutex_lock_active(&t->as->lock);

    if (--t->as->refcount == 0) {

        mutex_unlock(&t->as->lock);

        as_destroy(t->as);

        /*

         * t->as is destroyed.

         */

    } else {

        mutex_unlock(&t->as->lock);

    }

    free(t);

    TASK = NULL;

}

/** Create new task with 1 thread and run it

 *

 * @param program_addr Address of program executable image.

 * @param name Program name.

 *

 * @return Task of the running program or NULL on error.

 */

task_t * task_run_program(void *program_addr, char *name)

{

    as_t *as;

    as_area_t *a;

    int rc;

    thread_t *t1, *t2;

    task_t *task;

    uspace_arg_t *kernel_uarg;

    as = as_create(0);

    ASSERT(as);

    rc = elf_load((elf_header_t *) program_addr, as);

    if (rc != EE_OK) {

        as_destroy(as);

        return NULL;

    }

    kernel_uarg = (uspace_arg_t *) malloc(sizeof(uspace_arg_t), 0);

    kernel_uarg->uspace_entry = (void *) ((elf_header_t *) program_addr)->e_entry;

    kernel_uarg->uspace_stack = (void *) USTACK_ADDRESS;

    kernel_uarg->uspace_thread_function = NULL;

    kernel_uarg->uspace_thread_arg = NULL;

    kernel_uarg->uspace_uarg = NULL;

    task = task_create(as, name);

    ASSERT(task);

    /*

     * Create the data as_area.

     */

    a = as_area_create(as, AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE,

        LOADED_PROG_STACK_PAGES_NO*PAGE_SIZE,

        USTACK_ADDRESS, AS_AREA_ATTR_NONE, &anon_backend, NULL);

    /*

     * Create the main thread.

     */

    t1 = thread_create(uinit, kernel_uarg, task, 0, "uinit");

    ASSERT(t1);

    /*

     * Create killer thread for the new task.

     */

    t2 = thread_create(ktaskgc, t1, task, 0, "ktaskgc");

    ASSERT(t2);

    thread_ready(t2);

    thread_ready(t1);

    return task;

}

/** Syscall for reading task ID from userspace.

 *

 * @param uspace_task_id Userspace address of 8-byte buffer where to store current task ID.

 *

 * @return 0 on success or an error code from @ref errno.h.

 */

__native sys_task_get_id(task_id_t *uspace_task_id)

{

    /*

     * No need to acquire lock on TASK because taskid

     * remains constant for the lifespan of the task.

     */

    return (__native) copy_to_uspace(uspace_task_id, &TASK->taskid, sizeof(TASK->taskid));

}

/** Find task structure corresponding to task ID.

 *

 * The tasks_lock must be already held by the caller of this function

 * and interrupts must be disabled.

 *

 * @param id Task ID.

 *

 * @return Task structure address or NULL if there is no such task ID.

 */

task_t *task_find_by_id(task_id_t id)

{

    btree_node_t *leaf;

    return (task_t *) btree_search(&tasks_btree, (btree_key_t) id, &leaf);

}

/** Kill task.

 *

 * @param id ID of the task to be killed.

 *

 * @return 0 on success or an error code from errno.h

 */

int task_kill(task_id_t id)

{

    ipl_t ipl;

    task_t *ta;

    thread_t *t;

    link_t *cur;

    if (id == 1)

        return EPERM;

    ipl = interrupts_disable();

    spinlock_lock(&tasks_lock);

    if (!(ta = task_find_by_id(id))) {

        spinlock_unlock(&tasks_lock);

        interrupts_restore(ipl);

        return ENOENT;

    }

    spinlock_lock(&ta->lock);

    ta->refcount++;

    spinlock_unlock(&ta->lock);

    btree_remove(&tasks_btree, ta->taskid, NULL);

    spinlock_unlock(&tasks_lock);

    t = thread_create(ktaskclnp, NULL, ta, 0, "ktaskclnp");

    spinlock_lock(&ta->lock);

    ta->accept_new_threads = false;

    ta->refcount--;

    /*

     * Interrupt all threads except this one.

     */

    for (cur = ta->th_head.next; cur != &ta->th_head; cur = cur->next) {

        thread_t *thr;

        bool  sleeping = false;

        thr = list_get_instance(cur, thread_t, th_link);

        if (thr == t)

            continue;

        spinlock_lock(&thr->lock);

        thr->interrupted = true;

        if (thr->state == Sleeping)

            sleeping = true;

        spinlock_unlock(&thr->lock);

        if (sleeping)

            waitq_interrupt_sleep(thr);

    }

    spinlock_unlock(&ta->lock);

    interrupts_restore(ipl);

    if (t)

        thread_ready(t);

    return 0;

}

/** Print task list */

void task_print_list(void)

{

    link_t *cur;

    ipl_t ipl;

    /* Messing with thread structures, avoid deadlock */

    ipl = interrupts_disable();

    spinlock_lock(&tasks_lock);

    for (cur = tasks_btree.leaf_head.next; cur != &tasks_btree.leaf_head; cur = cur->next) {

        btree_node_t *node;

        int i;

        node = list_get_instance(cur, btree_node_t, leaf_link);

        for (i = 0; i < node->keys; i++) {

            task_t *t;

            int j;

            t = (task_t *) node->value[i];

            spinlock_lock(&t->lock);

            printf("%s(%lld): address=%#zX, as=%#zX, ActiveCalls: %zd",

                t->name, t->taskid, t, t->as, atomic_get(&t->active_calls));

            for (j=0; j < IPC_MAX_PHONES; j++) {

                if (t->phones[j].callee)

                    printf(" Ph(%zd): %#zX ", j, t->phones[j].callee);

            }

            printf("\n");

            spinlock_unlock(&t->lock);

        }

    }

    spinlock_unlock(&tasks_lock);

    interrupts_restore(ipl);

}

/** Kernel thread used to cleanup the task after it is killed. */

void ktaskclnp(void *arg)

{

    ipl_t ipl;

    thread_t *t = NULL, *main_thread;

    link_t *cur;

    bool again;

    thread_detach(THREAD);

loop:

    ipl = interrupts_disable();

    spinlock_lock(&TASK->lock);

    main_thread = TASK->main_thread;

    /*

     * Find a thread to join.

     */

    again = false;

    for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {

        t = list_get_instance(cur, thread_t, th_link);

        spinlock_lock(&t->lock);

        if (t == THREAD) {

            spinlock_unlock(&t->lock);

            continue;

        } else if (t == main_thread) {

            spinlock_unlock(&t->lock);

            continue;

        } else if (t->join_type != None) {

            spinlock_unlock(&t->lock);

            again = true;

            continue;

        } else {

            t->join_type = TaskClnp;

            spinlock_unlock(&t->lock);

            again = false;

            break;

        }

    }

    spinlock_unlock(&TASK->lock);

    interrupts_restore(ipl);

    if (again) {

        /*

         * Other cleanup (e.g. ktaskgc) is in progress.

         */

        scheduler();

        goto loop;

    }

    if (t != THREAD) {

        ASSERT(t != main_thread);   /* uninit is joined and detached in ktaskgc */

        thread_join(t);

        thread_detach(t);

        goto loop;  /* go for another thread */

    }

    /*

     * Now there are no other threads in this task

     * and no new threads can be created.

     */

    ipc_cleanup();

    futex_cleanup();

    klog_printf("Cleanup of task %lld completed.", TASK->taskid);

}

/** Kernel task used to kill a userspace task when its main thread exits.

 *

 * This thread waits until the main userspace thread (i.e. uninit) exits.

 * When this happens, the task is killed. In the meantime, exited threads

 * are garbage collected.

 *

 * @param arg Pointer to the thread structure of the task's main thread.

 */

void ktaskgc(void *arg)

{

    thread_t *t = (thread_t *) arg;

loop:  

    /*

     * Userspace threads cannot detach themselves,

     * therefore the thread pointer is guaranteed to be valid.

     */

    if (thread_join_timeout(t, 1000000, SYNCH_FLAGS_NONE) == ESYNCH_TIMEOUT) {  /* sleep uninterruptibly here! */

        ipl_t ipl;

        link_t *cur;

        thread_t *thr = NULL;

        /*

         * The join timed out. Try to do some garbage collection of Undead threads.

         */

more_gc:       

        ipl = interrupts_disable();

        spinlock_lock(&TASK->lock);

        for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {

            thr = list_get_instance(cur, thread_t, th_link);

            spinlock_lock(&thr->lock);

            if (thr->state == Undead && thr->join_type == None) {

                thr->join_type = TaskGC;

                spinlock_unlock(&thr->lock);

                break;

            }

            spinlock_unlock(&thr->lock);

            thr = NULL;

        }

        spinlock_unlock(&TASK->lock);

        interrupts_restore(ipl);

        if (thr) {

            thread_join(thr);

            thread_detach(thr);

            scheduler();

            goto more_gc;

        }

        goto loop;

    }

    thread_detach(t);

    task_kill(TASK->taskid);

}