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  1. /*
  2.  * Copyright (C) 2001-2004 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /**
  30.  * @file    task.c
  31.  * @brief   Task management.
  32.  */
  33.  
  34. #include <main/uinit.h>
  35. #include <proc/thread.h>
  36. #include <proc/task.h>
  37. #include <proc/uarg.h>
  38. #include <mm/as.h>
  39. #include <mm/slab.h>
  40. #include <synch/spinlock.h>
  41. #include <arch.h>
  42. #include <panic.h>
  43. #include <adt/btree.h>
  44. #include <adt/list.h>
  45. #include <ipc/ipc.h>
  46. #include <security/cap.h>
  47. #include <memstr.h>
  48. #include <print.h>
  49. #include <elf.h>
  50. #include <errno.h>
  51. #include <syscall/copy.h>
  52. #include <console/klog.h>
  53.  
  54. #ifndef LOADED_PROG_STACK_PAGES_NO
  55. #define LOADED_PROG_STACK_PAGES_NO 1
  56. #endif
  57.  
  58. /** Spinlock protecting the tasks_btree B+tree. */
  59. SPINLOCK_INITIALIZE(tasks_lock);
  60.  
  61. /** B+tree of active tasks.
  62.  *
  63.  * The task is guaranteed to exist after it was found in the tasks_btree as long as:
  64.  * @li the tasks_lock is held,
  65.  * @li the task's lock is held when task's lock is acquired before releasing tasks_lock or
  66.  * @li the task's refcount is grater than 0
  67.  *
  68.  */
  69. btree_t tasks_btree;
  70.  
  71. static task_id_t task_counter = 0;
  72.  
  73. static void ktaskclnp(void *arg);
  74. static void ktaskgc(void *arg);
  75.  
  76. /** Initialize tasks
  77.  *
  78.  * Initialize kernel tasks support.
  79.  *
  80.  */
  81. void task_init(void)
  82. {
  83.     TASK = NULL;
  84.     btree_create(&tasks_btree);
  85. }
  86.  
  87.  
  88. /** Create new task
  89.  *
  90.  * Create new task with no threads.
  91.  *
  92.  * @param as Task's address space.
  93.  * @param name Symbolic name.
  94.  *
  95.  * @return New task's structure
  96.  *
  97.  */
  98. task_t *task_create(as_t *as, char *name)
  99. {
  100.     ipl_t ipl;
  101.     task_t *ta;
  102.     int i;
  103.    
  104.     ta = (task_t *) malloc(sizeof(task_t), 0);
  105.  
  106.     task_create_arch(ta);
  107.  
  108.     spinlock_initialize(&ta->lock, "task_ta_lock");
  109.     list_initialize(&ta->th_head);
  110.     ta->as = as;
  111.     ta->name = name;
  112.     ta->main_thread = NULL;
  113.     ta->refcount = 0;
  114.  
  115.     ta->capabilities = 0;
  116.     ta->accept_new_threads = true;
  117.    
  118.     ipc_answerbox_init(&ta->answerbox);
  119.     for (i=0; i < IPC_MAX_PHONES;i++)
  120.         ipc_phone_init(&ta->phones[i]);
  121.     if (ipc_phone_0)
  122.         ipc_phone_connect(&ta->phones[0], ipc_phone_0);
  123.     atomic_set(&ta->active_calls, 0);
  124.  
  125.     mutex_initialize(&ta->futexes_lock);
  126.     btree_create(&ta->futexes);
  127.    
  128.     ipl = interrupts_disable();
  129.  
  130.     /*
  131.      * Increment address space reference count.
  132.      * TODO: Reconsider the locking scheme.
  133.      */
  134.     mutex_lock(&as->lock);
  135.     as->refcount++;
  136.     mutex_unlock(&as->lock);
  137.  
  138.     spinlock_lock(&tasks_lock);
  139.  
  140.     ta->taskid = ++task_counter;
  141.     btree_insert(&tasks_btree, (btree_key_t) ta->taskid, (void *) ta, NULL);
  142.  
  143.     spinlock_unlock(&tasks_lock);
  144.     interrupts_restore(ipl);
  145.  
  146.     return ta;
  147. }
  148.  
  149. /** Destroy task.
  150.  *
  151.  * @param t Task to be destroyed.
  152.  */
  153. void task_destroy(task_t *t)
  154. {
  155.     task_destroy_arch(t);
  156.     btree_destroy(&t->futexes);
  157.  
  158.     mutex_lock_active(&t->as->lock);
  159.     if (--t->as->refcount == 0) {
  160.         mutex_unlock(&t->as->lock);
  161.         as_destroy(t->as);
  162.         /*
  163.          * t->as is destroyed.
  164.          */
  165.     } else {
  166.         mutex_unlock(&t->as->lock);
  167.     }
  168.    
  169.     free(t);
  170.     TASK = NULL;
  171. }
  172.  
  173. /** Create new task with 1 thread and run it
  174.  *
  175.  * @param program_addr Address of program executable image.
  176.  * @param name Program name.
  177.  *
  178.  * @return Task of the running program or NULL on error.
  179.  */
  180. task_t * task_run_program(void *program_addr, char *name)
  181. {
  182.     as_t *as;
  183.     as_area_t *a;
  184.     int rc;
  185.     thread_t *t1, *t2;
  186.     task_t *task;
  187.     uspace_arg_t *kernel_uarg;
  188.  
  189.     as = as_create(0);
  190.     ASSERT(as);
  191.  
  192.     rc = elf_load((elf_header_t *) program_addr, as);
  193.     if (rc != EE_OK) {
  194.         as_destroy(as);
  195.         return NULL;
  196.     }
  197.    
  198.     kernel_uarg = (uspace_arg_t *) malloc(sizeof(uspace_arg_t), 0);
  199.     kernel_uarg->uspace_entry = (void *) ((elf_header_t *) program_addr)->e_entry;
  200.     kernel_uarg->uspace_stack = (void *) USTACK_ADDRESS;
  201.     kernel_uarg->uspace_thread_function = NULL;
  202.     kernel_uarg->uspace_thread_arg = NULL;
  203.     kernel_uarg->uspace_uarg = NULL;
  204.    
  205.     task = task_create(as, name);
  206.     ASSERT(task);
  207.  
  208.     /*
  209.      * Create the data as_area.
  210.      */
  211.     a = as_area_create(as, AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE,
  212.         LOADED_PROG_STACK_PAGES_NO*PAGE_SIZE,
  213.         USTACK_ADDRESS, AS_AREA_ATTR_NONE, &anon_backend, NULL);
  214.  
  215.     /*
  216.      * Create the main thread.
  217.      */
  218.     t1 = thread_create(uinit, kernel_uarg, task, 0, "uinit");
  219.     ASSERT(t1);
  220.    
  221.     /*
  222.      * Create killer thread for the new task.
  223.      */
  224.     t2 = thread_create(ktaskgc, t1, task, 0, "ktaskgc");
  225.     ASSERT(t2);
  226.     thread_ready(t2);
  227.  
  228.     thread_ready(t1);
  229.  
  230.     return task;
  231. }
  232.  
  233. /** Syscall for reading task ID from userspace.
  234.  *
  235.  * @param uspace_task_id Userspace address of 8-byte buffer where to store current task ID.
  236.  *
  237.  * @return 0 on success or an error code from @ref errno.h.
  238.  */
  239. __native sys_task_get_id(task_id_t *uspace_task_id)
  240. {
  241.     /*
  242.      * No need to acquire lock on TASK because taskid
  243.      * remains constant for the lifespan of the task.
  244.      */
  245.     return (__native) copy_to_uspace(uspace_task_id, &TASK->taskid, sizeof(TASK->taskid));
  246. }
  247.  
  248. /** Find task structure corresponding to task ID.
  249.  *
  250.  * The tasks_lock must be already held by the caller of this function
  251.  * and interrupts must be disabled.
  252.  *
  253.  * @param id Task ID.
  254.  *
  255.  * @return Task structure address or NULL if there is no such task ID.
  256.  */
  257. task_t *task_find_by_id(task_id_t id)
  258. {
  259.     btree_node_t *leaf;
  260.    
  261.     return (task_t *) btree_search(&tasks_btree, (btree_key_t) id, &leaf);
  262. }
  263.  
  264. /** Kill task.
  265.  *
  266.  * @param id ID of the task to be killed.
  267.  *
  268.  * @return 0 on success or an error code from errno.h
  269.  */
  270. int task_kill(task_id_t id)
  271. {
  272.     ipl_t ipl;
  273.     task_t *ta;
  274.     thread_t *t;
  275.     link_t *cur;
  276.  
  277.     if (id == 1)
  278.         return EPERM;
  279.    
  280.     ipl = interrupts_disable();
  281.     spinlock_lock(&tasks_lock);
  282.  
  283.     if (!(ta = task_find_by_id(id))) {
  284.         spinlock_unlock(&tasks_lock);
  285.         interrupts_restore(ipl);
  286.         return ENOENT;
  287.     }
  288.  
  289.     spinlock_lock(&ta->lock);
  290.     ta->refcount++;
  291.     spinlock_unlock(&ta->lock);
  292.  
  293.     btree_remove(&tasks_btree, ta->taskid, NULL);
  294.     spinlock_unlock(&tasks_lock);
  295.    
  296.     t = thread_create(ktaskclnp, NULL, ta, 0, "ktaskclnp");
  297.    
  298.     spinlock_lock(&ta->lock);
  299.     ta->accept_new_threads = false;
  300.     ta->refcount--;
  301.  
  302.     /*
  303.      * Interrupt all threads except ktaskclnp.
  304.      */
  305.     for (cur = ta->th_head.next; cur != &ta->th_head; cur = cur->next) {
  306.         thread_t *thr;
  307.         bool  sleeping = false;
  308.        
  309.         thr = list_get_instance(cur, thread_t, th_link);
  310.         if (thr == t)
  311.             continue;
  312.            
  313.         spinlock_lock(&thr->lock);
  314.         thr->interrupted = true;
  315.         if (thr->state == Sleeping)
  316.             sleeping = true;
  317.         spinlock_unlock(&thr->lock);
  318.        
  319.         if (sleeping)
  320.             waitq_interrupt_sleep(thr);
  321.     }
  322.    
  323.     spinlock_unlock(&ta->lock);
  324.     interrupts_restore(ipl);
  325.    
  326.     if (t)
  327.         thread_ready(t);
  328.  
  329.     return 0;
  330. }
  331.  
  332. /** Print task list */
  333. void task_print_list(void)
  334. {
  335.     link_t *cur;
  336.     ipl_t ipl;
  337.    
  338.     /* Messing with thread structures, avoid deadlock */
  339.     ipl = interrupts_disable();
  340.     spinlock_lock(&tasks_lock);
  341.  
  342.     for (cur = tasks_btree.leaf_head.next; cur != &tasks_btree.leaf_head; cur = cur->next) {
  343.         btree_node_t *node;
  344.         int i;
  345.        
  346.         node = list_get_instance(cur, btree_node_t, leaf_link);
  347.         for (i = 0; i < node->keys; i++) {
  348.             task_t *t;
  349.             int j;
  350.  
  351.             t = (task_t *) node->value[i];
  352.        
  353.             spinlock_lock(&t->lock);
  354.             printf("%s(%lld): address=%#zX, as=%#zX, ActiveCalls: %zd",
  355.                 t->name, t->taskid, t, t->as, atomic_get(&t->active_calls));
  356.             for (j=0; j < IPC_MAX_PHONES; j++) {
  357.                 if (t->phones[j].callee)
  358.                     printf(" Ph(%zd): %#zX ", j, t->phones[j].callee);
  359.             }
  360.             printf("\n");
  361.             spinlock_unlock(&t->lock);
  362.         }
  363.     }
  364.  
  365.     spinlock_unlock(&tasks_lock);
  366.     interrupts_restore(ipl);
  367. }
  368.  
  369. /** Kernel thread used to cleanup the task after it is killed. */
  370. void ktaskclnp(void *arg)
  371. {
  372.     ipl_t ipl;
  373.     thread_t *t = NULL, *main_thread;
  374.     link_t *cur;
  375.     bool again;
  376.  
  377.     thread_detach(THREAD);
  378.  
  379. loop:
  380.     ipl = interrupts_disable();
  381.     spinlock_lock(&TASK->lock);
  382.    
  383.     main_thread = TASK->main_thread;
  384.    
  385.     /*
  386.      * Find a thread to join.
  387.      */
  388.     again = false;
  389.     for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {
  390.         t = list_get_instance(cur, thread_t, th_link);
  391.  
  392.         spinlock_lock(&t->lock);
  393.         if (t == THREAD) {
  394.             spinlock_unlock(&t->lock);
  395.             continue;
  396.         } else if (t == main_thread) {
  397.             spinlock_unlock(&t->lock);
  398.             continue;
  399.         } else if (t->join_type != None) {
  400.             spinlock_unlock(&t->lock);
  401.             again = true;
  402.             continue;
  403.         } else {
  404.             t->join_type = TaskClnp;
  405.             spinlock_unlock(&t->lock);
  406.             again = false;
  407.             break;
  408.         }
  409.     }
  410.    
  411.     spinlock_unlock(&TASK->lock);
  412.     interrupts_restore(ipl);
  413.    
  414.     if (again) {
  415.         /*
  416.          * Other cleanup (e.g. ktaskgc) is in progress.
  417.          */
  418.         scheduler();
  419.         goto loop;
  420.     }
  421.    
  422.     if (t != THREAD) {
  423.         ASSERT(t != main_thread);   /* uninit is joined and detached in ktaskgc */
  424.         thread_join(t);
  425.         thread_detach(t);
  426.         goto loop;  /* go for another thread */
  427.     }
  428.    
  429.     /*
  430.      * Now there are no other threads in this task
  431.      * and no new threads can be created.
  432.      */
  433.    
  434.     ipc_cleanup();
  435.     futex_cleanup();
  436.     klog_printf("Cleanup of task %lld completed.", TASK->taskid);
  437. }
  438.  
  439. /** Kernel thread used to kill the userspace task when its main thread exits.
  440.  *
  441.  * This thread waits until the main userspace thread (i.e. uninit) exits.
  442.  * When this happens, the task is killed. In the meantime, exited threads
  443.  * are garbage collected.
  444.  *
  445.  * @param arg Pointer to the thread structure of the task's main thread.
  446.  */
  447. void ktaskgc(void *arg)
  448. {
  449.     thread_t *t = (thread_t *) arg;
  450. loop:  
  451.     /*
  452.      * Userspace threads cannot detach themselves,
  453.      * therefore the thread pointer is guaranteed to be valid.
  454.      */
  455.     if (thread_join_timeout(t, 1000000, SYNCH_FLAGS_NONE) == ESYNCH_TIMEOUT) {  /* sleep uninterruptibly here! */
  456.         ipl_t ipl;
  457.         link_t *cur;
  458.         thread_t *thr = NULL;
  459.    
  460.         /*
  461.          * The join timed out. Try to do some garbage collection of Undead threads.
  462.          */
  463. more_gc:       
  464.         ipl = interrupts_disable();
  465.         spinlock_lock(&TASK->lock);
  466.        
  467.         for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {
  468.             thr = list_get_instance(cur, thread_t, th_link);
  469.             spinlock_lock(&thr->lock);
  470.             if (thr != t && thr->state == Undead && thr->join_type == None) {
  471.                 thr->join_type = TaskGC;
  472.                 spinlock_unlock(&thr->lock);
  473.                 break;
  474.             }
  475.             spinlock_unlock(&thr->lock);
  476.             thr = NULL;
  477.         }
  478.         spinlock_unlock(&TASK->lock);
  479.         interrupts_restore(ipl);
  480.        
  481.         if (thr) {
  482.             thread_join(thr);
  483.             thread_detach(thr);
  484.             scheduler();
  485.             goto more_gc;
  486.         }
  487.            
  488.         goto loop;
  489.     }
  490.     thread_detach(t);
  491.     task_kill(TASK->taskid);
  492. }
  493.