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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   Thread management functions.

 */

#include <proc/scheduler.h>

#include <proc/thread.h>

#include <proc/task.h>

#include <proc/uarg.h>

#include <mm/frame.h>

#include <mm/page.h>

#include <arch/asm.h>

#include <arch/cycle.h>

#include <arch.h>

#include <synch/synch.h>

#include <synch/spinlock.h>

#include <synch/waitq.h>

#include <synch/rwlock.h>

#include <cpu.h>

#include <func.h>

#include <context.h>

#include <adt/avl.h>

#include <adt/list.h>

#include <time/clock.h>

#include <time/timeout.h>

#include <config.h>

#include <arch/interrupt.h>

#include <smp/ipi.h>

#include <arch/faddr.h>

#include <atomic.h>

#include <memstr.h>

#include <print.h>

#include <mm/slab.h>

#include <debug.h>

#include <main/uinit.h>

#include <syscall/copy.h>

#include <errno.h>

#include <console/klog.h>

/** Thread states */

char *thread_states[] = {

    "Invalid",

    "Running",

    "Sleeping",

    "Ready",

    "Entering",

    "Exiting",

    "Lingering"

};

/** Lock protecting the threads_tree AVL tree.

 *

 * For locking rules, see declaration thereof.

 */

SPINLOCK_INITIALIZE(threads_lock);

/** ALV tree of all threads.

 *

 * When a thread is found in the threads_tree AVL tree, it is guaranteed to

 * exist as long as the threads_lock is held.

 */

avltree_t threads_tree;    

SPINLOCK_INITIALIZE(tidlock);

thread_id_t last_tid = 0;

static slab_cache_t *thread_slab;

#ifdef ARCH_HAS_FPU

slab_cache_t *fpu_context_slab;

#endif

/** Thread wrapper.

 *

 * This wrapper is provided to ensure that every thread makes a call to

 * thread_exit() when its implementing function returns.

 *

 * interrupts_disable() is assumed.

 *

 */

static void cushion(void)

{

    void (*f)(void *) = THREAD->thread_code;

    void *arg = THREAD->thread_arg;

    THREAD->last_cycle = get_cycle();

    /* This is where each thread wakes up after its creation */

    spinlock_unlock(&THREAD->lock);

    interrupts_enable();

    f(arg);

    /* Accumulate accounting to the task */

    ipl_t ipl = interrupts_disable();

    spinlock_lock(&THREAD->lock);

    if (!THREAD->uncounted) {

        thread_update_accounting();

        uint64_t cycles = THREAD->cycles;

        THREAD->cycles = 0;

        spinlock_unlock(&THREAD->lock);

        spinlock_lock(&TASK->lock);

        TASK->cycles += cycles;

        spinlock_unlock(&TASK->lock);

    } else

        spinlock_unlock(&THREAD->lock);

    interrupts_restore(ipl);

    thread_exit();

    /* not reached */

}

/** Initialization and allocation for thread_t structure */

static int thr_constructor(void *obj, int kmflags)

{

    thread_t *t = (thread_t *) obj;

    spinlock_initialize(&t->lock, "thread_t_lock");

    link_initialize(&t->rq_link);

    link_initialize(&t->wq_link);

    link_initialize(&t->th_link);

    /* call the architecture-specific part of the constructor */

    thr_constructor_arch(t);

#ifdef ARCH_HAS_FPU

#ifdef CONFIG_FPU_LAZY

    t->saved_fpu_context = NULL;

#else

    t->saved_fpu_context = slab_alloc(fpu_context_slab, kmflags);

    if (!t->saved_fpu_context)

        return -1;

#endif

#endif  

    t->kstack = (uint8_t *) frame_alloc(STACK_FRAMES, FRAME_KA | kmflags);

    if (!t->kstack) {

#ifdef ARCH_HAS_FPU

        if (t->saved_fpu_context)

            slab_free(fpu_context_slab, t->saved_fpu_context);

#endif

        return -1;

    }

    return 0;

}

/** Destruction of thread_t object */

static int thr_destructor(void *obj)

{

    thread_t *t = (thread_t *) obj;

    /* call the architecture-specific part of the destructor */

    thr_destructor_arch(t);

    frame_free(KA2PA(t->kstack));

#ifdef ARCH_HAS_FPU

    if (t->saved_fpu_context)

        slab_free(fpu_context_slab, t->saved_fpu_context);

#endif

    return 1; /* One page freed */

}

/** Initialize threads

 *

 * Initialize kernel threads support.

 *

 */

void thread_init(void)

{

    THREAD = NULL;

    atomic_set(&nrdy,0);

    thread_slab = slab_cache_create("thread_slab", sizeof(thread_t), 0,

        thr_constructor, thr_destructor, 0);

#ifdef ARCH_HAS_FPU

    fpu_context_slab = slab_cache_create("fpu_slab", sizeof(fpu_context_t),

        FPU_CONTEXT_ALIGN, NULL, NULL, 0);

#endif

    avltree_create(&threads_tree);

}

/** Make thread ready

 *

 * Switch thread t to the ready state.

 *

 * @param t Thread to make ready.

 *

 */

void thread_ready(thread_t *t)

{

    cpu_t *cpu;

    runq_t *r;

    ipl_t ipl;

    int i, avg;

    ipl = interrupts_disable();

    spinlock_lock(&t->lock);

    ASSERT(!(t->state == Ready));

    i = (t->priority < RQ_COUNT - 1) ? ++t->priority : t->priority;

    cpu = CPU;

    if (t->flags & THREAD_FLAG_WIRED) {

        ASSERT(t->cpu != NULL);

        cpu = t->cpu;

    }

    t->state = Ready;

    spinlock_unlock(&t->lock);

    /*

     * Append t to respective ready queue on respective processor.

     */

    r = &cpu->rq[i];

    spinlock_lock(&r->lock);

    list_append(&t->rq_link, &r->rq_head);

    r->n++;

    spinlock_unlock(&r->lock);

    atomic_inc(&nrdy);

    avg = atomic_get(&nrdy) / config.cpu_active;

    atomic_inc(&cpu->nrdy);

    interrupts_restore(ipl);

}

/** Create new thread

 *

 * Create a new thread.

 *

 * @param func      Thread's implementing function.

 * @param arg       Thread's implementing function argument.

 * @param task      Task to which the thread belongs.

 * @param flags     Thread flags.

 * @param name      Symbolic name.

 * @param uncounted Thread's accounting doesn't affect accumulated task

 *          accounting.

 *

 * @return New thread's structure on success, NULL on failure.

 *

 */

thread_t *thread_create(void (* func)(void *), void *arg, task_t *task,

    int flags, char *name, bool uncounted)

{

    thread_t *t;

    ipl_t ipl;

    t = (thread_t *) slab_alloc(thread_slab, 0);

    if (!t)

        return NULL;

    /* Not needed, but good for debugging */

    memsetb((uintptr_t) t->kstack, THREAD_STACK_SIZE * 1 << STACK_FRAMES,

        0);

    ipl = interrupts_disable();

    spinlock_lock(&tidlock);

    t->tid = ++last_tid;

    spinlock_unlock(&tidlock);

    interrupts_restore(ipl);

    context_save(&t->saved_context);

    context_set(&t->saved_context, FADDR(cushion), (uintptr_t) t->kstack,

        THREAD_STACK_SIZE);

    the_initialize((the_t *) t->kstack);

    ipl = interrupts_disable();

    t->saved_context.ipl = interrupts_read();

    interrupts_restore(ipl);

    memcpy(t->name, name, THREAD_NAME_BUFLEN);

    t->thread_code = func;

    t->thread_arg = arg;

    t->ticks = -1;

    t->cycles = 0;

    t->uncounted = uncounted;

    t->priority = -1;       /* start in rq[0] */

    t->cpu = NULL;

    t->flags = flags;

    t->state = Entering;

    t->call_me = NULL;

    t->call_me_with = NULL;

    timeout_initialize(&t->sleep_timeout);

    t->sleep_interruptible = false;

    t->sleep_queue = NULL;

    t->timeout_pending = 0;

    t->in_copy_from_uspace = false;

    t->in_copy_to_uspace = false;

    t->interrupted = false;

    t->detached = false;

    waitq_initialize(&t->join_wq);

    t->rwlock_holder_type = RWLOCK_NONE;

    t->task = task;

    t->fpu_context_exists = 0;

    t->fpu_context_engaged = 0;

    avltree_node_initialize(&t->threads_tree_node);

    t->threads_tree_node.key = (uintptr_t) t;

    waitq_initialize(&t->go_wq);

    /* might depend on previous initialization */

    thread_create_arch(t); 

    if (!(flags & THREAD_FLAG_NOATTACH))

        thread_attach(t, task);

    return t;

}

/** Destroy thread memory structure

 *

 * Detach thread from all queues, cpus etc. and destroy it.

 *

 * Assume thread->lock is held!!

 */

void thread_destroy(thread_t *t)

{

    ASSERT(t->state == Exiting || t->state == Lingering);

    ASSERT(t->task);

    ASSERT(t->cpu);

    spinlock_lock(&t->cpu->lock);

    if (t->cpu->fpu_owner == t)

        t->cpu->fpu_owner = NULL;

    spinlock_unlock(&t->cpu->lock);

    spinlock_unlock(&t->lock);

    spinlock_lock(&threads_lock);

    avltree_delete(&threads_tree, &t->threads_tree_node);

    spinlock_unlock(&threads_lock);

    /*

     * Detach from the containing task.

     */

    spinlock_lock(&t->task->lock);

    list_remove(&t->th_link);

    spinlock_unlock(&t->task->lock);   

    /*

     * t is guaranteed to be the very last thread of its task.

     * It is safe to destroy the task.

     */

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

        task_destroy(t->task);

    slab_free(thread_slab, t);

}

/** Make the thread visible to the system.

 *

 * Attach the thread structure to the current task and make it visible in the

 * threads_tree.

 *

 * @param t Thread to be attached to the task.

 * @param task  Task to which the thread is to be attached.

 */

void thread_attach(thread_t *t, task_t *task)

{

    ipl_t ipl;

    /*

     * Attach to the current task.

     */

    ipl = interrupts_disable();

    spinlock_lock(&task->lock);

    atomic_inc(&task->refcount);

    atomic_inc(&task->lifecount);

    /* FIXME: this must be done very carefully.. an unstoppable

       thread cannot appear just-so, it must be possible to catch it. */

    if (t->flags & THREAD_FLAG_USPACE)

        ++task->not_stoppable_count;

    list_append(&t->th_link, &task->th_head);

    spinlock_unlock(&task->lock);

    /*

     * Register this thread in the system-wide list.

     */

    spinlock_lock(&threads_lock);

    avltree_insert(&threads_tree, &t->threads_tree_node);

    spinlock_unlock(&threads_lock);

    interrupts_restore(ipl);

}

/** Terminate thread.

 *

 * End current thread execution and switch it to the exiting state. All pending

 * timeouts are executed.

 */

void thread_exit(void)

{

    ipl_t ipl;

    if (atomic_predec(&TASK->lifecount) == 0) {

        /*

         * We are the last thread in the task that still has not exited.

         * With the exception of the moment the task was created, new

         * threads can only be created by threads of the same task.

         * We are safe to perform cleanup.

         */

        if (THREAD->flags & THREAD_FLAG_USPACE) {

            ipc_cleanup();

                futex_cleanup();

            klog_printf("Cleanup of task %llu completed.",

                TASK->taskid);

        }

    }

restart:

    ipl = interrupts_disable();

    spinlock_lock(&THREAD->lock);

    if (THREAD->timeout_pending) {

        /* busy waiting for timeouts in progress */

        spinlock_unlock(&THREAD->lock);

        interrupts_restore(ipl);

        goto restart;

    }

    THREAD->state = Exiting;

    spinlock_unlock(&THREAD->lock);

    scheduler();

    /* Not reached */

    while (1)

        ;

}

/** Thread sleep

 *

 * Suspend execution of the current thread.

 *

 * @param sec Number of seconds to sleep.

 *

 */

void thread_sleep(uint32_t sec)

{

    thread_usleep(sec * 1000000);

}

/** Wait for another thread to exit.

 *

 * @param t Thread to join on exit.

 * @param usec Timeout in microseconds.

 * @param flags Mode of operation.

 *

 * @return An error code from errno.h or an error code from synch.h.

 */

int thread_join_timeout(thread_t *t, uint32_t usec, int flags)

{

    ipl_t ipl;

    int rc;

    if (t == THREAD)

        return EINVAL;

    /*

     * Since thread join can only be called once on an undetached thread,

     * the thread pointer is guaranteed to be still valid.

     */

    ipl = interrupts_disable();

    spinlock_lock(&t->lock);

    ASSERT(!t->detached);

    spinlock_unlock(&t->lock);

    interrupts_restore(ipl);

    rc = waitq_sleep_timeout(&t->join_wq, usec, flags);

    return rc; 

}

/** Detach thread.

 *

 * Mark the thread as detached, if the thread is already in the Lingering

 * state, deallocate its resources.

 *

 * @param t Thread to be detached.

 */

void thread_detach(thread_t *t)

{

    ipl_t ipl;

    /*

     * Since the thread is expected not to be already detached,

     * pointer to it must be still valid.

     */

    ipl = interrupts_disable();

    spinlock_lock(&t->lock);

    ASSERT(!t->detached);

    if (t->state == Lingering) {

        thread_destroy(t);  /* unlocks &t->lock */

        interrupts_restore(ipl);

        return;

    } else {

        t->detached = true;

    }

    spinlock_unlock(&t->lock);

    interrupts_restore(ipl);

}

/** Thread usleep

 *

 * Suspend execution of the current thread.

 *

 * @param usec Number of microseconds to sleep.

 *

 */

void thread_usleep(uint32_t usec)

{

    waitq_t wq;

    waitq_initialize(&wq);

    (void) waitq_sleep_timeout(&wq, usec, SYNCH_FLAGS_NON_BLOCKING);

}

/** Register thread out-of-context invocation

 *

 * Register a function and its argument to be executed

 * on next context switch to the current thread.

 *

 * @param call_me      Out-of-context function.

 * @param call_me_with Out-of-context function argument.

 *

 */

void thread_register_call_me(void (* call_me)(void *), void *call_me_with)

{

    ipl_t ipl;

    ipl = interrupts_disable();

    spinlock_lock(&THREAD->lock);

    THREAD->call_me = call_me;

    THREAD->call_me_with = call_me_with;

    spinlock_unlock(&THREAD->lock);

    interrupts_restore(ipl);

}

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

{

    thread_t *t;

    t = avltree_get_instance(node, thread_t, threads_tree_node);

    uint64_t cycles;

    char suffix;

    order(t->cycles, &cycles, &suffix);

    if (sizeof(void *) == 4)

        printf("%-6llu %-10s %#10zx %-8s %#10zx %-3ld %#10zx %#10zx %9llu%c ",

            t->tid, t->name, t, thread_states[t->state], t->task,

            t->task->context, t->thread_code, t->kstack, cycles, suffix);

    else

        printf("%-6llu %-10s %#18zx %-8s %#18zx %-3ld %#18zx %#18zx %9llu%c ",

            t->tid, t->name, t, thread_states[t->state], t->task,

            t->task->context, t->thread_code, t->kstack, cycles, suffix);

    if (t->cpu)

        printf("%-4zd", t->cpu->id);

    else

        printf("none");

    if (t->state == Sleeping) {

        if (sizeof(uintptr_t) == 4)

            printf(" %#10zx", t->sleep_queue);

        else

            printf(" %#18zx", t->sleep_queue);

    }

    printf("\n");

    return true;

}

/** Print list of threads debug info */

void thread_print_list(void)

{

    ipl_t ipl;

    /* Messing with thread structures, avoid deadlock */

    ipl = interrupts_disable();

    spinlock_lock(&threads_lock);

    if (sizeof(uintptr_t) == 4) {

        printf("tid    name       address    state    task       "

            "ctx code       stack      cycles     cpu  "

            "waitqueue\n");

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

            "--- ---------- ---------- ---------- ---- "

            "----------\n");

    } else {

        printf("tid    name       address            state    task               "

            "ctx code               stack              cycles     cpu  "

            "waitqueue\n");

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

            "--- ------------------ ------------------ ---------- ---- "

            "------------------\n");

    }

    avltree_walk(&threads_tree, thread_walker, NULL);

    spinlock_unlock(&threads_lock);

    interrupts_restore(ipl);

}

/** Check whether thread exists.

 *

 * Note that threads_lock must be already held and

 * interrupts must be already disabled.

 *

 * @param t Pointer to thread.

 *

 * @return True if thread t is known to the system, false otherwise.

 */

bool thread_exists(thread_t *t)

{

    avltree_node_t *node;

    node = avltree_search(&threads_tree, (avltree_key_t) ((uintptr_t) t));

    return node != NULL;

}

/** Update accounting of current thread.

 *

 * Note that thread_lock on THREAD must be already held and

 * interrupts must be already disabled.

 *

 */

void thread_update_accounting(void)

{

    uint64_t time = get_cycle();

    THREAD->cycles += time - THREAD->last_cycle;

    THREAD->last_cycle = time;

}

/** Process syscall to create new thread.

 *

 */

unative_t sys_thread_create(uspace_arg_t *uspace_uarg, char *uspace_name,

    thread_id_t *uspace_thread_id)

{

    thread_t *t;

    char namebuf[THREAD_NAME_BUFLEN];

    uspace_arg_t *kernel_uarg;

    int rc;

    rc = copy_from_uspace(namebuf, uspace_name, THREAD_NAME_BUFLEN);

    if (rc != 0)

        return (unative_t) rc;

    /*

     * In case of failure, kernel_uarg will be deallocated in this function.

     * In case of success, kernel_uarg will be freed in uinit().

     */

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

    rc = copy_from_uspace(kernel_uarg, uspace_uarg, sizeof(uspace_arg_t));

    if (rc != 0) {

        free(kernel_uarg);

        return (unative_t) rc;

    }

    t = thread_create(uinit, kernel_uarg, TASK,

        THREAD_FLAG_USPACE | THREAD_FLAG_NOATTACH, namebuf, false);

    if (t) {

        if (uspace_thread_id != NULL) {

            int rc;

            rc = copy_to_uspace(uspace_thread_id, &t->tid,

                sizeof(t->tid));

            if (rc != 0) {

                /*

                 * We have encountered a failure, but the thread

                 * has already been created. We need to undo its

                 * creation now.

                 */

                /*

                 * The new thread structure is initialized, but

                 * is still not visible to the system.

                 * We can safely deallocate it.

                 */

                slab_free(thread_slab, t);

                free(kernel_uarg);

                return (unative_t) rc;

             }

        }

        thread_attach(t, TASK);

        thread_ready(t);

        return 0;

    } else

        free(kernel_uarg);

    return (unative_t) ENOMEM;

}

/** Process syscall to terminate thread.

 *

 */

unative_t sys_thread_exit(int uspace_status)

{

    thread_exit();

    /* Unreachable */

    return 0;

}

/** Syscall for getting TID.

 *

 * @param uspace_thread_id Userspace address of 8-byte buffer where to store

 * current thread ID.

 *

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

 */

unative_t sys_thread_get_id(thread_id_t *uspace_thread_id)

{

    /*

     * No need to acquire lock on THREAD because tid

     * remains constant for the lifespan of the thread.

     */

    return (unative_t) copy_to_uspace(uspace_thread_id, &THREAD->tid,

        sizeof(THREAD->tid));

}

/** @}

 */