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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. /** @addtogroup genericproc
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief   Thread management functions.
  36.  */
  37.  
  38. #include <proc/scheduler.h>
  39. #include <proc/thread.h>
  40. #include <proc/task.h>
  41. #include <proc/uarg.h>
  42. #include <mm/frame.h>
  43. #include <mm/page.h>
  44. #include <arch/asm.h>
  45. #include <arch/cycle.h>
  46. #include <arch.h>
  47. #include <synch/synch.h>
  48. #include <synch/spinlock.h>
  49. #include <synch/waitq.h>
  50. #include <synch/rwlock.h>
  51. #include <cpu.h>
  52. #include <func.h>
  53. #include <context.h>
  54. #include <adt/avl.h>
  55. #include <adt/list.h>
  56. #include <time/clock.h>
  57. #include <time/timeout.h>
  58. #include <config.h>
  59. #include <arch/interrupt.h>
  60. #include <smp/ipi.h>
  61. #include <arch/faddr.h>
  62. #include <atomic.h>
  63. #include <memstr.h>
  64. #include <print.h>
  65. #include <mm/slab.h>
  66. #include <debug.h>
  67. #include <main/uinit.h>
  68. #include <syscall/copy.h>
  69. #include <errno.h>
  70.  
  71.  
  72. #ifndef LOADED_PROG_STACK_PAGES_NO
  73. #define LOADED_PROG_STACK_PAGES_NO 1
  74. #endif
  75.  
  76.  
  77. /** Thread states */
  78. char *thread_states[] = {
  79.     "Invalid",
  80.     "Running",
  81.     "Sleeping",
  82.     "Ready",
  83.     "Entering",
  84.     "Exiting",
  85.     "Lingering"
  86. };
  87.  
  88. /** Lock protecting the threads_tree AVL tree.
  89.  *
  90.  * For locking rules, see declaration thereof.
  91.  */
  92. SPINLOCK_INITIALIZE(threads_lock);
  93.  
  94. /** AVL tree of all threads.
  95.  *
  96.  * When a thread is found in the threads_tree AVL tree, it is guaranteed to
  97.  * exist as long as the threads_lock is held.
  98.  */
  99. avltree_t threads_tree;    
  100.  
  101. SPINLOCK_INITIALIZE(tidlock);
  102. thread_id_t last_tid = 0;
  103.  
  104. static slab_cache_t *thread_slab;
  105. #ifdef ARCH_HAS_FPU
  106. slab_cache_t *fpu_context_slab;
  107. #endif
  108.  
  109. /** Thread wrapper.
  110.  *
  111.  * This wrapper is provided to ensure that every thread makes a call to
  112.  * thread_exit() when its implementing function returns.
  113.  *
  114.  * interrupts_disable() is assumed.
  115.  *
  116.  */
  117. static void cushion(void)
  118. {
  119.     void (*f)(void *) = THREAD->thread_code;
  120.     void *arg = THREAD->thread_arg;
  121.     THREAD->last_cycle = get_cycle();
  122.  
  123.     /* This is where each thread wakes up after its creation */
  124.     spinlock_unlock(&THREAD->lock);
  125.     interrupts_enable();
  126.  
  127.     f(arg);
  128.    
  129.     /* Accumulate accounting to the task */
  130.     ipl_t ipl = interrupts_disable();
  131.    
  132.     spinlock_lock(&THREAD->lock);
  133.     if (!THREAD->uncounted) {
  134.         thread_update_accounting();
  135.         uint64_t cycles = THREAD->cycles;
  136.         THREAD->cycles = 0;
  137.         spinlock_unlock(&THREAD->lock);
  138.        
  139.         spinlock_lock(&TASK->lock);
  140.         TASK->cycles += cycles;
  141.         spinlock_unlock(&TASK->lock);
  142.     } else
  143.         spinlock_unlock(&THREAD->lock);
  144.    
  145.     interrupts_restore(ipl);
  146.    
  147.     thread_exit();
  148.     /* not reached */
  149. }
  150.  
  151. /** Initialization and allocation for thread_t structure */
  152. static int thr_constructor(void *obj, int kmflags)
  153. {
  154.     thread_t *t = (thread_t *) obj;
  155.  
  156.     spinlock_initialize(&t->lock, "thread_t_lock");
  157.     link_initialize(&t->rq_link);
  158.     link_initialize(&t->wq_link);
  159.     link_initialize(&t->th_link);
  160.  
  161.     /* call the architecture-specific part of the constructor */
  162.     thr_constructor_arch(t);
  163.    
  164. #ifdef ARCH_HAS_FPU
  165. #ifdef CONFIG_FPU_LAZY
  166.     t->saved_fpu_context = NULL;
  167. #else
  168.     t->saved_fpu_context = slab_alloc(fpu_context_slab, kmflags);
  169.     if (!t->saved_fpu_context)
  170.         return -1;
  171. #endif
  172. #endif 
  173.  
  174.     t->kstack = (uint8_t *) frame_alloc(STACK_FRAMES, FRAME_KA | kmflags);
  175.     if (!t->kstack) {
  176. #ifdef ARCH_HAS_FPU
  177.         if (t->saved_fpu_context)
  178.             slab_free(fpu_context_slab, t->saved_fpu_context);
  179. #endif
  180.         return -1;
  181.     }
  182.  
  183.     return 0;
  184. }
  185.  
  186. /** Destruction of thread_t object */
  187. static int thr_destructor(void *obj)
  188. {
  189.     thread_t *t = (thread_t *) obj;
  190.  
  191.     /* call the architecture-specific part of the destructor */
  192.     thr_destructor_arch(t);
  193.  
  194.     frame_free(KA2PA(t->kstack));
  195. #ifdef ARCH_HAS_FPU
  196.     if (t->saved_fpu_context)
  197.         slab_free(fpu_context_slab, t->saved_fpu_context);
  198. #endif
  199.     return 1; /* One page freed */
  200. }
  201.  
  202. /** Initialize threads
  203.  *
  204.  * Initialize kernel threads support.
  205.  *
  206.  */
  207. void thread_init(void)
  208. {
  209.     THREAD = NULL;
  210.     atomic_set(&nrdy,0);
  211.     thread_slab = slab_cache_create("thread_slab", sizeof(thread_t), 0,
  212.         thr_constructor, thr_destructor, 0);
  213.  
  214. #ifdef ARCH_HAS_FPU
  215.     fpu_context_slab = slab_cache_create("fpu_slab", sizeof(fpu_context_t),
  216.         FPU_CONTEXT_ALIGN, NULL, NULL, 0);
  217. #endif
  218.  
  219.     avltree_create(&threads_tree);
  220. }
  221.  
  222. /** Make thread ready
  223.  *
  224.  * Switch thread t to the ready state.
  225.  *
  226.  * @param t Thread to make ready.
  227.  *
  228.  */
  229. void thread_ready(thread_t *t)
  230. {
  231.     cpu_t *cpu;
  232.     runq_t *r;
  233.     ipl_t ipl;
  234.     int i, avg;
  235.  
  236.     ipl = interrupts_disable();
  237.  
  238.     spinlock_lock(&t->lock);
  239.  
  240.     ASSERT(!(t->state == Ready));
  241.  
  242.     i = (t->priority < RQ_COUNT - 1) ? ++t->priority : t->priority;
  243.    
  244.     cpu = CPU;
  245.     if (t->flags & THREAD_FLAG_WIRED) {
  246.         ASSERT(t->cpu != NULL);
  247.         cpu = t->cpu;
  248.     }
  249.     t->state = Ready;
  250.     spinlock_unlock(&t->lock);
  251.    
  252.     /*
  253.      * Append t to respective ready queue on respective processor.
  254.      */
  255.     r = &cpu->rq[i];
  256.     spinlock_lock(&r->lock);
  257.     list_append(&t->rq_link, &r->rq_head);
  258.     r->n++;
  259.     spinlock_unlock(&r->lock);
  260.  
  261.     atomic_inc(&nrdy);
  262.     avg = atomic_get(&nrdy) / config.cpu_active;
  263.     atomic_inc(&cpu->nrdy);
  264.  
  265.     interrupts_restore(ipl);
  266. }
  267.  
  268. /** Create new thread
  269.  *
  270.  * Create a new thread.
  271.  *
  272.  * @param func      Thread's implementing function.
  273.  * @param arg       Thread's implementing function argument.
  274.  * @param task      Task to which the thread belongs. The caller must
  275.  *          guarantee that the task won't cease to exist during the
  276.  *          call. The task's lock may not be held.
  277.  * @param flags     Thread flags.
  278.  * @param name      Symbolic name.
  279.  * @param uncounted Thread's accounting doesn't affect accumulated task
  280.  *          accounting.
  281.  *
  282.  * @return      New thread's structure on success, NULL on failure.
  283.  *
  284.  */
  285. thread_t *thread_create(void (* func)(void *), void *arg, task_t *task,
  286.     int flags, char *name, bool uncounted)
  287. {
  288.     thread_t *t;
  289.     ipl_t ipl;
  290.    
  291.     t = (thread_t *) slab_alloc(thread_slab, 0);
  292.     if (!t)
  293.         return NULL;
  294.    
  295.     /* Not needed, but good for debugging */
  296.     memsetb((uintptr_t) t->kstack, THREAD_STACK_SIZE * 1 << STACK_FRAMES,
  297.         0);
  298.    
  299.     ipl = interrupts_disable();
  300.     spinlock_lock(&tidlock);
  301.     t->tid = ++last_tid;
  302.     spinlock_unlock(&tidlock);
  303.     interrupts_restore(ipl);
  304.    
  305.     context_save(&t->saved_context);
  306.     context_set(&t->saved_context, FADDR(cushion), (uintptr_t) t->kstack,
  307.         THREAD_STACK_SIZE);
  308.    
  309.     the_initialize((the_t *) t->kstack);
  310.    
  311.     ipl = interrupts_disable();
  312.     t->saved_context.ipl = interrupts_read();
  313.     interrupts_restore(ipl);
  314.    
  315.     memcpy(t->name, name, THREAD_NAME_BUFLEN);
  316.    
  317.     t->thread_code = func;
  318.     t->thread_arg = arg;
  319.     t->ticks = -1;
  320.     t->cycles = 0;
  321.     t->uncounted = uncounted;
  322.     t->priority = -1;       /* start in rq[0] */
  323.     t->cpu = NULL;
  324.     t->flags = flags;
  325.     t->state = Entering;
  326.     t->call_me = NULL;
  327.     t->call_me_with = NULL;
  328.    
  329.     timeout_initialize(&t->sleep_timeout);
  330.     t->sleep_interruptible = false;
  331.     t->sleep_queue = NULL;
  332.     t->timeout_pending = 0;
  333.  
  334.     t->in_copy_from_uspace = false;
  335.     t->in_copy_to_uspace = false;
  336.  
  337.     t->interrupted = false;
  338.     t->detached = false;
  339.     waitq_initialize(&t->join_wq);
  340.    
  341.     t->rwlock_holder_type = RWLOCK_NONE;
  342.        
  343.     t->task = task;
  344.    
  345.     t->fpu_context_exists = 0;
  346.     t->fpu_context_engaged = 0;
  347.  
  348.     avltree_node_initialize(&t->threads_tree_node);
  349.     t->threads_tree_node.key = (uintptr_t) t;
  350.  
  351.     /* might depend on previous initialization */
  352.     thread_create_arch(t); 
  353.  
  354.     if (!(flags & THREAD_FLAG_NOATTACH))
  355.         thread_attach(t, task);
  356.  
  357.     return t;
  358. }
  359.  
  360. /** Destroy thread memory structure
  361.  *
  362.  * Detach thread from all queues, cpus etc. and destroy it.
  363.  *
  364.  * Assume thread->lock is held!!
  365.  */
  366. void thread_destroy(thread_t *t)
  367. {
  368.     ASSERT(t->state == Exiting || t->state == Lingering);
  369.     ASSERT(t->task);
  370.     ASSERT(t->cpu);
  371.  
  372.     spinlock_lock(&t->cpu->lock);
  373.     if (t->cpu->fpu_owner == t)
  374.         t->cpu->fpu_owner = NULL;
  375.     spinlock_unlock(&t->cpu->lock);
  376.  
  377.     spinlock_unlock(&t->lock);
  378.  
  379.     spinlock_lock(&threads_lock);
  380.     avltree_delete(&threads_tree, &t->threads_tree_node);
  381.     spinlock_unlock(&threads_lock);
  382.  
  383.     /*
  384.      * Detach from the containing task.
  385.      */
  386.     spinlock_lock(&t->task->lock);
  387.     list_remove(&t->th_link);
  388.     spinlock_unlock(&t->task->lock);   
  389.  
  390.     /*
  391.      * t is guaranteed to be the very last thread of its task.
  392.      * It is safe to destroy the task.
  393.      */
  394.     if (atomic_predec(&t->task->refcount) == 0)
  395.         task_destroy(t->task);
  396.    
  397.     slab_free(thread_slab, t);
  398. }
  399.  
  400. /** Make the thread visible to the system.
  401.  *
  402.  * Attach the thread structure to the current task and make it visible in the
  403.  * threads_tree.
  404.  *
  405.  * @param t Thread to be attached to the task.
  406.  * @param task  Task to which the thread is to be attached.
  407.  */
  408. void thread_attach(thread_t *t, task_t *task)
  409. {
  410.     ipl_t ipl;
  411.  
  412.     /*
  413.      * Attach to the current task.
  414.      */
  415.     ipl = interrupts_disable();
  416.     spinlock_lock(&task->lock);
  417.     atomic_inc(&task->refcount);
  418.     atomic_inc(&task->lifecount);
  419.     list_append(&t->th_link, &task->th_head);
  420.     spinlock_unlock(&task->lock);
  421.  
  422.     /*
  423.      * Register this thread in the system-wide list.
  424.      */
  425.     spinlock_lock(&threads_lock);
  426.     avltree_insert(&threads_tree, &t->threads_tree_node);
  427.     spinlock_unlock(&threads_lock);
  428.    
  429.     interrupts_restore(ipl);
  430. }
  431.  
  432. /** Terminate thread.
  433.  *
  434.  * End current thread execution and switch it to the exiting state. All pending
  435.  * timeouts are executed.
  436.  */
  437. void thread_exit(void)
  438. {
  439.     ipl_t ipl;
  440.  
  441.     if (atomic_predec(&TASK->lifecount) == 0) {
  442.         /*
  443.          * We are the last thread in the task that still has not exited.
  444.          * With the exception of the moment the task was created, new
  445.          * threads can only be created by threads of the same task.
  446.          * We are safe to perform cleanup.
  447.          */
  448.         if (THREAD->flags & THREAD_FLAG_USPACE) {
  449.             ipc_cleanup();
  450.             futex_cleanup();
  451.             LOG("Cleanup of task %" PRIu64" completed.", TASK->taskid);
  452.         }
  453.     }
  454.  
  455. restart:
  456.     ipl = interrupts_disable();
  457.     spinlock_lock(&THREAD->lock);
  458.     if (THREAD->timeout_pending) {
  459.         /* busy waiting for timeouts in progress */
  460.         spinlock_unlock(&THREAD->lock);
  461.         interrupts_restore(ipl);
  462.         goto restart;
  463.     }
  464.    
  465.     THREAD->state = Exiting;
  466.     spinlock_unlock(&THREAD->lock);
  467.     scheduler();
  468.  
  469.     /* Not reached */
  470.     while (1)
  471.         ;
  472. }
  473.  
  474.  
  475. /** Thread sleep
  476.  *
  477.  * Suspend execution of the current thread.
  478.  *
  479.  * @param sec Number of seconds to sleep.
  480.  *
  481.  */
  482. void thread_sleep(uint32_t sec)
  483. {
  484.     thread_usleep(sec * 1000000);
  485. }
  486.  
  487. /** Wait for another thread to exit.
  488.  *
  489.  * @param t Thread to join on exit.
  490.  * @param usec Timeout in microseconds.
  491.  * @param flags Mode of operation.
  492.  *
  493.  * @return An error code from errno.h or an error code from synch.h.
  494.  */
  495. int thread_join_timeout(thread_t *t, uint32_t usec, int flags)
  496. {
  497.     ipl_t ipl;
  498.     int rc;
  499.  
  500.     if (t == THREAD)
  501.         return EINVAL;
  502.  
  503.     /*
  504.      * Since thread join can only be called once on an undetached thread,
  505.      * the thread pointer is guaranteed to be still valid.
  506.      */
  507.    
  508.     ipl = interrupts_disable();
  509.     spinlock_lock(&t->lock);
  510.     ASSERT(!t->detached);
  511.     spinlock_unlock(&t->lock);
  512.     interrupts_restore(ipl);
  513.    
  514.     rc = waitq_sleep_timeout(&t->join_wq, usec, flags);
  515.    
  516.     return rc; 
  517. }
  518.  
  519. /** Detach thread.
  520.  *
  521.  * Mark the thread as detached, if the thread is already in the Lingering
  522.  * state, deallocate its resources.
  523.  *
  524.  * @param t Thread to be detached.
  525.  */
  526. void thread_detach(thread_t *t)
  527. {
  528.     ipl_t ipl;
  529.  
  530.     /*
  531.      * Since the thread is expected not to be already detached,
  532.      * pointer to it must be still valid.
  533.      */
  534.     ipl = interrupts_disable();
  535.     spinlock_lock(&t->lock);
  536.     ASSERT(!t->detached);
  537.     if (t->state == Lingering) {
  538.         thread_destroy(t);  /* unlocks &t->lock */
  539.         interrupts_restore(ipl);
  540.         return;
  541.     } else {
  542.         t->detached = true;
  543.     }
  544.     spinlock_unlock(&t->lock);
  545.     interrupts_restore(ipl);
  546. }
  547.  
  548. /** Thread usleep
  549.  *
  550.  * Suspend execution of the current thread.
  551.  *
  552.  * @param usec Number of microseconds to sleep.
  553.  *
  554.  */
  555. void thread_usleep(uint32_t usec)
  556. {
  557.     waitq_t wq;
  558.                  
  559.     waitq_initialize(&wq);
  560.  
  561.     (void) waitq_sleep_timeout(&wq, usec, SYNCH_FLAGS_NON_BLOCKING);
  562. }
  563.  
  564. /** Register thread out-of-context invocation
  565.  *
  566.  * Register a function and its argument to be executed
  567.  * on next context switch to the current thread.
  568.  *
  569.  * @param call_me      Out-of-context function.
  570.  * @param call_me_with Out-of-context function argument.
  571.  *
  572.  */
  573. void thread_register_call_me(void (* call_me)(void *), void *call_me_with)
  574. {
  575.     ipl_t ipl;
  576.    
  577.     ipl = interrupts_disable();
  578.     spinlock_lock(&THREAD->lock);
  579.     THREAD->call_me = call_me;
  580.     THREAD->call_me_with = call_me_with;
  581.     spinlock_unlock(&THREAD->lock);
  582.     interrupts_restore(ipl);
  583. }
  584.  
  585. static bool thread_walker(avltree_node_t *node, void *arg)
  586. {
  587.     thread_t *t = avltree_get_instance(node, thread_t, threads_tree_node);
  588.    
  589.     uint64_t cycles;
  590.     char suffix;
  591.     order(t->cycles, &cycles, &suffix);
  592.  
  593. #ifdef __32_BITS__
  594.     printf("%-6" PRIu64" %-10s %10p %-8s %10p %-3" PRIu32 " %10p %10p %9" PRIu64 "%c ",
  595.         t->tid, t->name, t, thread_states[t->state], t->task,
  596.         t->task->context, t->thread_code, t->kstack, cycles, suffix);
  597. #endif
  598.  
  599. #ifdef __64_BITS__
  600.     printf("%-6" PRIu64" %-10s %18p %-8s %18p %-3" PRIu32 " %18p %18p %9" PRIu64 "%c ",
  601.         t->tid, t->name, t, thread_states[t->state], t->task,
  602.         t->task->context, t->thread_code, t->kstack, cycles, suffix);
  603. #endif
  604.            
  605.     if (t->cpu)
  606.         printf("%-4u", t->cpu->id);
  607.     else
  608.         printf("none");
  609.            
  610.     if (t->state == Sleeping) {
  611. #ifdef __32_BITS__
  612.         printf(" %10p", t->sleep_queue);
  613. #endif
  614.  
  615. #ifdef __64_BITS__
  616.         printf(" %18p", t->sleep_queue);
  617. #endif
  618.     }
  619.            
  620.     printf("\n");
  621.  
  622.     return true;
  623. }
  624.  
  625. /** Print list of threads debug info */
  626. void thread_print_list(void)
  627. {
  628.     ipl_t ipl;
  629.    
  630.     /* Messing with thread structures, avoid deadlock */
  631.     ipl = interrupts_disable();
  632.     spinlock_lock(&threads_lock);
  633.  
  634. #ifdef __32_BITS__ 
  635.     printf("tid    name       address    state    task       "
  636.         "ctx code       stack      cycles     cpu  "
  637.         "waitqueue\n");
  638.     printf("------ ---------- ---------- -------- ---------- "
  639.         "--- ---------- ---------- ---------- ---- "
  640.         "----------\n");
  641. #endif
  642.  
  643. #ifdef __64_BITS__
  644.     printf("tid    name       address            state    task               "
  645.         "ctx code               stack              cycles     cpu  "
  646.         "waitqueue\n");
  647.     printf("------ ---------- ------------------ -------- ------------------ "
  648.         "--- ------------------ ------------------ ---------- ---- "
  649.         "------------------\n");
  650. #endif
  651.  
  652.     avltree_walk(&threads_tree, thread_walker, NULL);
  653.  
  654.     spinlock_unlock(&threads_lock);
  655.     interrupts_restore(ipl);
  656. }
  657.  
  658. /** Check whether thread exists.
  659.  *
  660.  * Note that threads_lock must be already held and
  661.  * interrupts must be already disabled.
  662.  *
  663.  * @param t Pointer to thread.
  664.  *
  665.  * @return True if thread t is known to the system, false otherwise.
  666.  */
  667. bool thread_exists(thread_t *t)
  668. {
  669.     avltree_node_t *node;
  670.  
  671.     node = avltree_search(&threads_tree, (avltree_key_t) ((uintptr_t) t));
  672.    
  673.     return node != NULL;
  674. }
  675.  
  676.  
  677. /** Create new user task with 1 thread from image
  678.  *
  679.  * @param program_addr Address of program executable image.
  680.  * @param name Program name.
  681.  *
  682.  * @return Initialized main thread of the task or NULL on error.
  683.  */
  684. thread_t *thread_create_program(void *program_addr, char *name)
  685. {
  686.     as_t *as;
  687.     as_area_t *area;
  688.     unsigned int rc;
  689.     task_t *task;
  690.     uspace_arg_t *kernel_uarg;
  691.    
  692.     kernel_uarg = (uspace_arg_t *) malloc(sizeof(uspace_arg_t), 0);
  693.     if (kernel_uarg == NULL)
  694.         return NULL;
  695.    
  696.     kernel_uarg->uspace_entry =
  697.         (void *) ((elf_header_t *) program_addr)->e_entry;
  698.     kernel_uarg->uspace_stack = (void *) USTACK_ADDRESS;
  699.     kernel_uarg->uspace_thread_function = NULL;
  700.     kernel_uarg->uspace_thread_arg = NULL;
  701.     kernel_uarg->uspace_uarg = NULL;
  702.  
  703.     as = as_create(0);
  704.     if (as == NULL) {
  705.         free(kernel_uarg);
  706.         return NULL;
  707.     }
  708.  
  709.     rc = elf_load((elf_header_t *) program_addr, as);
  710.     if (rc != EE_OK) {
  711.         free(kernel_uarg);
  712.         as_destroy(as);
  713.         return NULL;
  714.     }
  715.    
  716.     /*
  717.      * Create the data as_area.
  718.      */
  719.     area = as_area_create(as,
  720.         AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE,
  721.         LOADED_PROG_STACK_PAGES_NO * PAGE_SIZE, USTACK_ADDRESS,
  722.         AS_AREA_ATTR_NONE, &anon_backend, NULL);
  723.     if (area == NULL) {
  724.         free(kernel_uarg);
  725.         as_destroy(as);
  726.         return NULL;
  727.     }
  728.    
  729.     task = task_create(as, name);
  730.     if (task == NULL) {
  731.         free(kernel_uarg);
  732.         as_destroy(as);
  733.         return NULL;
  734.     }
  735.    
  736.     /*
  737.      * Create the main thread.
  738.      */
  739.     return thread_create(uinit, kernel_uarg, task, THREAD_FLAG_USPACE,
  740.         "uinit", false);
  741. }
  742.  
  743.  
  744. /** Update accounting of current thread.
  745.  *
  746.  * Note that thread_lock on THREAD must be already held and
  747.  * interrupts must be already disabled.
  748.  *
  749.  */
  750. void thread_update_accounting(void)
  751. {
  752.     uint64_t time = get_cycle();
  753.     THREAD->cycles += time - THREAD->last_cycle;
  754.     THREAD->last_cycle = time;
  755. }
  756.  
  757. /** Process syscall to create new thread.
  758.  *
  759.  */
  760. unative_t sys_thread_create(uspace_arg_t *uspace_uarg, char *uspace_name,
  761.     thread_id_t *uspace_thread_id)
  762. {
  763.     thread_t *t;
  764.     char namebuf[THREAD_NAME_BUFLEN];
  765.     uspace_arg_t *kernel_uarg;
  766.     int rc;
  767.  
  768.     rc = copy_from_uspace(namebuf, uspace_name, THREAD_NAME_BUFLEN);
  769.     if (rc != 0)
  770.         return (unative_t) rc;
  771.  
  772.     /*
  773.      * In case of failure, kernel_uarg will be deallocated in this function.
  774.      * In case of success, kernel_uarg will be freed in uinit().
  775.      */
  776.     kernel_uarg = (uspace_arg_t *) malloc(sizeof(uspace_arg_t), 0);
  777.    
  778.     rc = copy_from_uspace(kernel_uarg, uspace_uarg, sizeof(uspace_arg_t));
  779.     if (rc != 0) {
  780.         free(kernel_uarg);
  781.         return (unative_t) rc;
  782.     }
  783.  
  784.     t = thread_create(uinit, kernel_uarg, TASK,
  785.         THREAD_FLAG_USPACE | THREAD_FLAG_NOATTACH, namebuf, false);
  786.     if (t) {
  787.         if (uspace_thread_id != NULL) {
  788.             int rc;
  789.  
  790.             rc = copy_to_uspace(uspace_thread_id, &t->tid,
  791.                 sizeof(t->tid));
  792.             if (rc != 0) {
  793.                 /*
  794.                  * We have encountered a failure, but the thread
  795.                  * has already been created. We need to undo its
  796.                  * creation now.
  797.                  */
  798.  
  799.                 /*
  800.                  * The new thread structure is initialized, but
  801.                  * is still not visible to the system.
  802.                  * We can safely deallocate it.
  803.                  */
  804.                 slab_free(thread_slab, t);
  805.                 free(kernel_uarg);
  806.  
  807.                 return (unative_t) rc;
  808.              }
  809.         }
  810.         thread_attach(t, TASK);
  811.         thread_ready(t);
  812.  
  813.         return 0;
  814.     } else
  815.         free(kernel_uarg);
  816.  
  817.     return (unative_t) ENOMEM;
  818. }
  819.  
  820. /** Process syscall to terminate thread.
  821.  *
  822.  */
  823. unative_t sys_thread_exit(int uspace_status)
  824. {
  825.     thread_exit();
  826.     /* Unreachable */
  827.     return 0;
  828. }
  829.  
  830. /** Syscall for getting TID.
  831.  *
  832.  * @param uspace_thread_id Userspace address of 8-byte buffer where to store
  833.  * current thread ID.
  834.  *
  835.  * @return 0 on success or an error code from @ref errno.h.
  836.  */
  837. unative_t sys_thread_get_id(thread_id_t *uspace_thread_id)
  838. {
  839.     /*
  840.      * No need to acquire lock on THREAD because tid
  841.      * remains constant for the lifespan of the thread.
  842.      */
  843.     return (unative_t) copy_to_uspace(uspace_thread_id, &THREAD->tid,
  844.         sizeof(THREAD->tid));
  845. }
  846.  
  847. /** @}
  848.  */
  849.