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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 <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 program_addr Address of program executable image.

 * @param name Program name. 

 *

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

 */

task_t *task_create_from_loader(char *name)

{

	as_t *as;

	unsigned int rc;

	as = as_create(0);

	ASSERT(as);

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

	if (rc != EE_OK) {

		as_destroy(as);

		return NULL;

	}

	return task_create_from_as(

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

}

/** 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 and stores its

 * task id into the provided buffer.

 *

 * @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_spawn(task_id_t *uspace_task_id)

{

	task_t *t;

	task_id_t fake_id;

	int rc;

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

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

	    sizeof(fake_id));

	if (rc != 0)

		return rc;

	t = task_create_from_loader("loader");

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

	rc = (unative_t) copy_to_uspace(uspace_task_id, &t->taskid,

	    sizeof(t->taskid));

	if (rc != 0) {

		/* Ooops */

		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);

}

/** @}

 */