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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 <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->context = CONTEXT;

	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) && (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.

	 * 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.

 */

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));

}

/** 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 ktaskclnp.

	 */	

	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): context=%ld, address=%#zx, as=%#zx, ActiveCalls: %zd",

				t->name, t->taskid, t->context, 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 thread used to kill the 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 != t && 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);

}

/** @}

 */