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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/btree.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>

/** 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);

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

	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 & 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->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;

	/* might depend on previous initialization */

	thread_create_arch(t);	

	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;

	} else {

		/*

		 * Bump the reference count so that this task cannot be

		 * destroyed while the new thread is being attached to it.

		 */

		task->refcount++;

	}

	spinlock_unlock(&task->lock);

	interrupts_restore(ipl);

	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)

{

	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) ((uintptr_t ) 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);

	/*

	 * If the thread had a userspace context, free up its kernel_uarg

	 * structure.

	 */

	if (t->flags & THREAD_FLAG_USPACE) {

		ASSERT(t->thread_arg);

		free(t->thread_arg);

	}

	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_btree.

 *

 * @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);

	ASSERT(task->refcount);

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

	if (task->refcount == 1)

		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) ((uintptr_t) t), (void *) t,

	    NULL);

	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;

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 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 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 == 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(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);

}

/** 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);

	printf("tid    name       address    state    task       ctx code    "

	    "   stack      cycles     cpu  kstack     waitqueue\n");

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

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

	for (cur = threads_btree.leaf_head.next;

	    cur != &threads_btree.leaf_head; cur = cur->next) {

		btree_node_t *node;

		unsigned 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];

			uint64_t cycles;

			char suffix;

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

			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);

			if (t->cpu)

				printf("%-4zd", t->cpu->id);

			else

				printf("none");

			if (t->state == Sleeping)

				printf(" %#10zx %#10zx", t->kstack,

				    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) ((uintptr_t) t),

	    &leaf) != 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;

	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) {

				ipl_t ipl;

				/*

				 * 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);

				/*

				 * Now we need to decrement the task reference

				 * counter. Because we are running within the

				 * same task, thread t is not the last thread

				 * in the task, so it is safe to merely

				 * decrement the counter.

				 */

				ipl = interrupts_disable();

				spinlock_lock(&TASK->lock);

				TASK->refcount--;

				spinlock_unlock(&TASK->lock);

				interrupts_restore(ipl);

				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));

}

/** @}

 */