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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.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/btree.h>
#include <adt/list.h>
#include <typedefs.h>
#include <time/clock.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>


/** Thread states */
char *thread_states[] = {
    "Invalid",
    "Running",
    "Sleeping",
    "Ready",
    "Entering",
    "Exiting",
    "Undead"
}; 

/** Lock protecting the threads_btree B+tree. For locking rules, see declaration thereof. */
SPINLOCK_INITIALIZE(threads_lock);

/** B+tree of all threads.
 *
 * When a thread is found in the threads_btree B+tree, it is guaranteed to exist as long
 * as the threads_lock is held.
 */
btree_t threads_btree;      

SPINLOCK_INITIALIZE(tidlock);
__u32 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;

    /* this is where each thread wakes up after its creation */
    spinlock_unlock(&THREAD->lock);
    interrupts_enable();

    f(arg);
    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;
    pfn_t pfn;
    int status;

    spinlock_initialize(&t->lock, "thread_t_lock");
    link_initialize(&t->rq_link);
    link_initialize(&t->wq_link);
    link_initialize(&t->th_link);
    
#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  

    pfn = frame_alloc_rc(STACK_FRAMES, FRAME_KA | kmflags,&status);
    if (status) {
#ifdef ARCH_HAS_FPU
        if (t->saved_fpu_context)
            slab_free(fpu_context_slab,t->saved_fpu_context);
#endif
        return -1;
    }
    t->kstack = (__u8 *)PA2KA(PFN2ADDR(pfn));

    return 0;
}

/** Destruction of thread_t object */
static int thr_destructor(void *obj)
{
    thread_t *t = (thread_t *)obj;

    frame_free(ADDR2PFN(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

    btree_create(&threads_btree);
}

/** 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 & X_WIRED) {
        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);
}

/** 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)
{
    bool destroy_task = false;  

    ASSERT(t->state == Exiting || t->state == Undead);
    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);
    btree_remove(&threads_btree, (btree_key_t) ((__address ) t), NULL);
    spinlock_unlock(&threads_lock);

    /*
     * Detach from the containing task.
     */
    spinlock_lock(&t->task->lock);
    list_remove(&t->th_link);
    if (--t->task->refcount == 0) {
        t->task->accept_new_threads = false;
        destroy_task = true;
    }
    spinlock_unlock(&t->task->lock);    
    
    if (destroy_task)
        task_destroy(t->task);
    
    slab_free(thread_slab, t);
}

/** 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.
 *
 * @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)
{
    thread_t *t;
    ipl_t ipl;
    
    t = (thread_t *) slab_alloc(thread_slab, 0);
    if (!t)
        return NULL;

    thread_create_arch(t);
    
    /* Not needed, but good for debugging */
    memsetb((__address)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), (__address) 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->priority = -1;       /* start in rq[0] */
    t->cpu = NULL;
    t->flags = 0;
    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->join_type = None;
    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;
    
    /*
     * Attach to the containing task.
     */
    ipl = interrupts_disable();  
    spinlock_lock(&task->lock);
    if (!task->accept_new_threads) {
        spinlock_unlock(&task->lock);
        slab_free(thread_slab, t);
        interrupts_restore(ipl);
        return NULL;
    }
    list_append(&t->th_link, &task->th_head);
    if (task->refcount++ == 0)
        task->main_thread = t;
    spinlock_unlock(&task->lock);

    /*
     * Register this thread in the system-wide list.
     */
    spinlock_lock(&threads_lock);
    btree_insert(&threads_btree, (btree_key_t) ((__address) t), (void *) t, NULL);
    spinlock_unlock(&threads_lock);
    
    interrupts_restore(ipl);
    
    return t;
}

/** 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;

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(__u32 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, __u32 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 Undead state,
 * deallocate its resources.
 *
 * @param t Thread to be detached.
 */
void thread_detach(thread_t *t)
{
    ipl_t ipl;

    /*
     * Since the thread is expected to not be already detached,
     * pointer to it must be still valid.
     */
    ipl = interrupts_disable();
    spinlock_lock(&t->lock);
    ASSERT(!t->detached);
    if (t->state == Undead) {
        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(__u32 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);
}

/** Print list of threads debug info */
void thread_print_list(void)
{
    link_t *cur;
    ipl_t ipl;
    
    /* Messing with thread structures, avoid deadlock */
    ipl = interrupts_disable();
    spinlock_lock(&threads_lock);

    for (cur = threads_btree.leaf_head.next; cur != &threads_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++) {
            thread_t *t;
        
            t = (thread_t *) node->value[i];
            printf("%s: address=%#zX, tid=%zd, state=%s, task=%#zX, code=%#zX, stack=%#zX, cpu=",
                t->name, t, t->tid, thread_states[t->state], t->task, t->thread_code, t->kstack);
            if (t->cpu)
                printf("cpu%zd", t->cpu->id);
            else
                printf("none");
            if (t->state == Sleeping) {
                printf(", kst=%#zX", t->kstack);
                printf(", wq=%#zX", t->sleep_queue);
            }
            printf("\n");
        }
    }

    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)
{
    btree_node_t *leaf;
    
    return btree_search(&threads_btree, (btree_key_t) ((__address) t), &leaf) != NULL;
}

/** Process syscall to create new thread.
 *
 */
__native sys_thread_create(uspace_arg_t *uspace_uarg, char *uspace_name)
{
    thread_t *t;
    char namebuf[THREAD_NAME_BUFLEN];
    uspace_arg_t *kernel_uarg;
    __u32 tid;
    int rc;

    rc = copy_from_uspace(namebuf, uspace_name, THREAD_NAME_BUFLEN);
    if (rc != 0)
        return (__native) rc;

    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 (__native) rc;
    }

    if ((t = thread_create(uinit, kernel_uarg, TASK, 0, namebuf))) {
        tid = t->tid;
        thread_ready(t);
        return (__native) tid; 
    } else {
        free(kernel_uarg);
    }

    return (__native) ENOMEM;
}

/** Process syscall to terminate thread.
 *
 */
__native sys_thread_exit(int uspace_status)
{
    thread_exit();
    /* Unreachable */
    return 0;
}

 /** @}
 */