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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.

 */

/** @addtogroup genericproc

 * @{

 */

/**

 * @file

 * @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 <atomic.h>

#include <synch/spinlock.h>

#include <synch/waitq.h>

#include <arch.h>

#include <panic.h>

#include <adt/avl.h>

#include <adt/btree.h>

#include <adt/list.h>

#include <ipc/ipc.h>

#include <ipc/ipcrsc.h>

#include <security/cap.h>

#include <memstr.h>

#include <print.h>

#include <lib/elf.h>

#include <errno.h>

#include <func.h>

#include <syscall/copy.h>

#ifndef LOADED_PROG_STACK_PAGES_NO

#define LOADED_PROG_STACK_PAGES_NO 1

#endif

/** Spinlock protecting the tasks_tree AVL tree. */

SPINLOCK_INITIALIZE(tasks_lock);

/** AVL tree of active tasks.

 *

 * The task is guaranteed to exist after it was found in the tasks_tree 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 greater than 0

 *

 */

avltree_t tasks_tree;

static task_id_t task_counter = 0;

/**

 * Points to the binary image used as the program loader. All non-initial

 * tasks are created from this executable image.

 */

void *program_loader = NULL;

/** Initialize tasks

 *

 * Initialize kernel tasks support.

 *

 */

void task_init(void)

{

    TASK = NULL;

    avltree_create(&tasks_tree);

}

/*

 * The idea behind this walker is to remember a single task different from TASK.

 */

static bool task_done_walker(avltree_node_t *node, void *arg)

{

    task_t *t = avltree_get_instance(node, task_t, tasks_tree_node);

    task_t **tp = (task_t **) arg;

    if (t != TASK) {

        *tp = t;

        return false;   /* stop walking */

    }

    return true;    /* continue the walk */

}

/** Kill all tasks except the current task.

 *

 */

void task_done(void)

{

    task_t *t;

    do { /* Repeat until there are any tasks except TASK */

        /* Messing with task structures, avoid deadlock */

        ipl_t ipl = interrupts_disable();

        spinlock_lock(&tasks_lock);

        t = NULL;

        avltree_walk(&tasks_tree, task_done_walker, &t);

        if (t != NULL) {

            task_id_t id = t->taskid;

            spinlock_unlock(&tasks_lock);

            interrupts_restore(ipl);

#ifdef CONFIG_DEBUG

            printf("Killing task %llu\n", id);

#endif          

            task_kill(id);

            thread_usleep(10000);

        } else {

            spinlock_unlock(&tasks_lock);

            interrupts_restore(ipl);

        }

    } while (t != NULL);

}

/** 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;

    atomic_set(&ta->refcount, 0);

    atomic_set(&ta->lifecount, 0);

    ta->context = CONTEXT;

    ta->capabilities = 0;

    ta->cycles = 0;

    ipc_answerbox_init(&ta->answerbox, ta);

    for (i = 0; i < IPC_MAX_PHONES; i++)

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

    if ((ipc_phone_0) && (context_check(ipc_phone_0->task->context,

        ta->context)))

        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.

     */

    atomic_inc(&as->refcount);

    spinlock_lock(&tasks_lock);

    ta->taskid = ++task_counter;

    avltree_node_initialize(&ta->tasks_tree_node);

    ta->tasks_tree_node.key = ta->taskid;

    avltree_insert(&tasks_tree, &ta->tasks_tree_node);

    spinlock_unlock(&tasks_lock);

    interrupts_restore(ipl);

    return ta;

}

/** Destroy task.

 *

 * @param t Task to be destroyed.

 */

void task_destroy(task_t *t)

{

    /*

     * Remove the task from the task B+tree.

     */

    spinlock_lock(&tasks_lock);

    avltree_delete(&tasks_tree, &t->tasks_tree_node);

    spinlock_unlock(&tasks_lock);

    /*

     * Perform architecture specific task destruction.

     */

    task_destroy_arch(t);

    /*

     * Free up dynamically allocated state.

     */

    btree_destroy(&t->futexes);

    /*

     * Drop our reference to the address space.

     */

    if (atomic_predec(&t->as->refcount) == 0)

        as_destroy(t->as);

    free(t);

    TASK = NULL;

}

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

 *

 * @param as Address space containing a binary program image.

 * @param entry_addr Program entry-point address in program address space.

 * @param name Program name.

 *

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

 */

task_t *task_create_from_as(as_t *as, uintptr_t entry_addr, char *name)

{

    as_area_t *a;

    thread_t *t;

    task_t *task;

    uspace_arg_t *kernel_uarg;

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

    kernel_uarg->uspace_entry = (void *) entry_addr;

    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.

     */

    t = thread_create(uinit, kernel_uarg, task, THREAD_FLAG_USPACE,

        "uinit", false);

    ASSERT(t);

    return task;

}

/** Parse an executable image in the physical memory.

 *

 * If the image belongs to a program loader, it is registered as such,

 * (and *task is set to NULL). Otherwise a task is created from the

 * executable image. The task is returned in *task.

 *

 * @param program_addr Address of program executable image.

 * @param name Program name.

 * @param task Where to store the pointer to the newly created task.

 *

 * @return EOK on success or negative error code.

 */

int task_parse_initial(void *program_addr, char *name, task_t **task)

{

    as_t *as;

    unsigned int rc;

    as = as_create(0);

    ASSERT(as);

    rc = elf_load((elf_header_t *) program_addr, as, 0);

    if (rc != EE_OK) {

        as_destroy(as);

        *task = NULL;

        if (rc != EE_LOADER)

            return ENOTSUP;

        /* Register image as the program loader */

        ASSERT(program_loader == NULL);

        program_loader = program_addr;

        return EOK;

    }

    *task = task_create_from_as(as, ((elf_header_t *) program_addr)->e_entry,

        name);

    return EOK;

}

/** Create a task from the program loader image.

 *

 * @param name Program name.

 * @param t Buffer for storing pointer to the newly created task.

 *

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

 */

int task_create_from_loader(char *name, task_t **t)

{

    as_t *as;

    unsigned int rc;

    void *loader;

    as = as_create(0);

    ASSERT(as);

    loader = program_loader;

    if (!loader) return ENOENT;

    rc = elf_load((elf_header_t *) program_loader, as, ELD_F_LOADER);

    if (rc != EE_OK) {

        as_destroy(as);

        return ENOENT;

    }

    *t = task_create_from_as(

        as, ((elf_header_t *) program_loader)->e_entry, name); 

    return EOK;

}

/** Make task ready.

 *

 * Switch task's thread to the ready state.

 *

 * @param ta Task to make ready.

 */

void task_ready(task_t *t)

{

    thread_t *th;

    th = list_get_instance(t->th_head.next, thread_t, th_link);

    thread_ready(th);

}

/** 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.

 */

unative_t 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 (unative_t) copy_to_uspace(uspace_task_id, &TASK->taskid,

        sizeof(TASK->taskid));

}

/** Syscall for creating a new task from userspace.

 *

 * Creates a new task from the program loader image, connects a phone

 * to it and stores the phone id into the provided buffer.

 *

 * @param uspace_phone_id Userspace address where to store the phone id.

 *

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

 */

unative_t sys_task_spawn(int *uspace_phone_id)

{

    task_t *t;

    int fake_id;

    int rc;

    int phone_id;

    fake_id = 0;

    /* Before we even try creating the task, see if we can write the id */

    rc = (unative_t) copy_to_uspace(uspace_phone_id, &fake_id,

        sizeof(fake_id));

    if (rc != 0)

        return rc;

    phone_id = phone_alloc();

    if (phone_id < 0)

        return ELIMIT;

    rc = task_create_from_loader("loader", &t);

    if (rc != 0)

        return rc;

    phone_connect(phone_id, &t->answerbox);

    /* No need to aquire lock before task_ready() */

    rc = (unative_t) copy_to_uspace(uspace_phone_id, &phone_id,

        sizeof(phone_id));

    if (rc != 0) {

        /* Ooops */

        ipc_phone_hangup(&TASK->phones[phone_id]);

        task_kill(t->taskid);

        return rc;

    }

    task_ready(t);

    return EOK;

}

/** 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)

{

    avltree_node_t *node;

    node = avltree_search(&tasks_tree, (avltree_key_t) id);

    if (node)

        return avltree_get_instance(node, task_t, tasks_tree_node);

    return NULL;

}

/** Get accounting data of given task.

 *

 * Note that task lock of 't' must be already held and

 * interrupts must be already disabled.

 *

 * @param t Pointer to thread.

 *

 */

uint64_t task_get_accounting(task_t *t)

{

    /* Accumulated value of task */

    uint64_t ret = t->cycles;

    /* Current values of threads */

    link_t *cur;

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

        thread_t *thr = list_get_instance(cur, thread_t, th_link);

        spinlock_lock(&thr->lock);

        /* Process only counted threads */

        if (!thr->uncounted) {

            if (thr == THREAD) {

                /* Update accounting of current thread */

                thread_update_accounting();

            }

            ret += thr->cycles;

        }

        spinlock_unlock(&thr->lock);

    }

    return ret;

}

/** Kill task.

 *

 * This function is idempotent.

 * It signals all the task's threads to bail it out.

 *

 * @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;

    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_unlock(&tasks_lock);

    /*

     * Interrupt all threads except ktaskclnp.

     */

    spinlock_lock(&ta->lock);

    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);

        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);

    return 0;

}

static bool task_print_walker(avltree_node_t *node, void *arg)

{

    task_t *t = avltree_get_instance(node, task_t, tasks_tree_node);

    int j;

    spinlock_lock(&t->lock);

    uint64_t cycles;

    char suffix;

    order(task_get_accounting(t), &cycles, &suffix);

    if (sizeof(void *) == 4)

        printf("%-6llu %-10s %-3ld %#10zx %#10zx %9llu%c %7zd %6zd",

            t->taskid, t->name, t->context, t, t->as, cycles, suffix,

            t->refcount, atomic_get(&t->active_calls));

    else

        printf("%-6llu %-10s %-3ld %#18zx %#18zx %9llu%c %7zd %6zd",

            t->taskid, t->name, t->context, t, t->as, cycles, suffix,

            t->refcount, atomic_get(&t->active_calls));

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

        if (t->phones[j].callee)

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

    }

    printf("\n");

    spinlock_unlock(&t->lock);

    return true;

}

/** Print task list */

void task_print_list(void)

{

    ipl_t ipl;

    /* Messing with task structures, avoid deadlock */

    ipl = interrupts_disable();

    spinlock_lock(&tasks_lock);

    if (sizeof(void *) == 4) {

        printf("taskid name       ctx address    as         "

            "cycles     threads calls  callee\n");

        printf("------ ---------- --- ---------- ---------- "

            "---------- ------- ------ ------>\n");

    } else {

        printf("taskid name       ctx address            as                 "

            "cycles     threads calls  callee\n");

        printf("------ ---------- --- ------------------ ------------------ "

            "---------- ------- ------ ------>\n");

    }

    avltree_walk(&tasks_tree, task_print_walker, NULL);

    spinlock_unlock(&tasks_lock);

    interrupts_restore(ipl);

}

/** @}

 */