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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(t->kstack, THREAD_STACK_SIZE * 1 << STACK_FRAMES, 0);
  297.    
  298.     ipl = interrupts_disable();
  299.     spinlock_lock(&tidlock);
  300.     t->tid = ++last_tid;
  301.     spinlock_unlock(&tidlock);
  302.     interrupts_restore(ipl);
  303.    
  304.     context_save(&t->saved_context);
  305.     context_set(&t->saved_context, FADDR(cushion), (uintptr_t) t->kstack,
  306.         THREAD_STACK_SIZE);
  307.    
  308.     the_initialize((the_t *) t->kstack);
  309.    
  310.     ipl = interrupts_disable();
  311.     t->saved_context.ipl = interrupts_read();
  312.     interrupts_restore(ipl);
  313.    
  314.     memcpy(t->name, name, THREAD_NAME_BUFLEN);
  315.    
  316.     t->thread_code = func;
  317.     t->thread_arg = arg;
  318.     t->ticks = -1;
  319.     t->cycles = 0;
  320.     t->uncounted = uncounted;
  321.     t->priority = -1;       /* start in rq[0] */
  322.     t->cpu = NULL;
  323.     t->flags = flags;
  324.     t->state = Entering;
  325.     t->call_me = NULL;
  326.     t->call_me_with = NULL;
  327.    
  328.     timeout_initialize(&t->sleep_timeout);
  329.     t->sleep_interruptible = false;
  330.     t->sleep_queue = NULL;
  331.     t->timeout_pending = 0;
  332.  
  333.     t->in_copy_from_uspace = false;
  334.     t->in_copy_to_uspace = false;
  335.  
  336.     t->interrupted = false;
  337.     t->detached = false;
  338.     waitq_initialize(&t->join_wq);
  339.    
  340.     t->rwlock_holder_type = RWLOCK_NONE;
  341.        
  342.     t->task = task;
  343.    
  344.     t->fpu_context_exists = 0;
  345.     t->fpu_context_engaged = 0;
  346.  
  347.     avltree_node_initialize(&t->threads_tree_node);
  348.     t->threads_tree_node.key = (uintptr_t) t;
  349.  
  350.     /* might depend on previous initialization */
  351.     thread_create_arch(t); 
  352.  
  353.     if (!(flags & THREAD_FLAG_NOATTACH))
  354.         thread_attach(t, task);
  355.  
  356.     return t;
  357. }
  358.  
  359. /** Destroy thread memory structure
  360.  *
  361.  * Detach thread from all queues, cpus etc. and destroy it.
  362.  *
  363.  * Assume thread->lock is held!!
  364.  */
  365. void thread_destroy(thread_t *t)
  366. {
  367.     ASSERT(t->state == Exiting || t->state == Lingering);
  368.     ASSERT(t->task);
  369.     ASSERT(t->cpu);
  370.  
  371.     spinlock_lock(&t->cpu->lock);
  372.     if (t->cpu->fpu_owner == t)
  373.         t->cpu->fpu_owner = NULL;
  374.     spinlock_unlock(&t->cpu->lock);
  375.  
  376.     spinlock_unlock(&t->lock);
  377.  
  378.     spinlock_lock(&threads_lock);
  379.     avltree_delete(&threads_tree, &t->threads_tree_node);
  380.     spinlock_unlock(&threads_lock);
  381.  
  382.     /*
  383.      * Detach from the containing task.
  384.      */
  385.     spinlock_lock(&t->task->lock);
  386.     list_remove(&t->th_link);
  387.     spinlock_unlock(&t->task->lock);   
  388.  
  389.     /*
  390.      * t is guaranteed to be the very last thread of its task.
  391.      * It is safe to destroy the task.
  392.      */
  393.     if (atomic_predec(&t->task->refcount) == 0)
  394.         task_destroy(t->task);
  395.    
  396.     slab_free(thread_slab, t);
  397. }
  398.  
  399. /** Make the thread visible to the system.
  400.  *
  401.  * Attach the thread structure to the current task and make it visible in the
  402.  * threads_tree.
  403.  *
  404.  * @param t Thread to be attached to the task.
  405.  * @param task  Task to which the thread is to be attached.
  406.  */
  407. void thread_attach(thread_t *t, task_t *task)
  408. {
  409.     ipl_t ipl;
  410.  
  411.     /*
  412.      * Attach to the current task.
  413.      */
  414.     ipl = interrupts_disable();
  415.     spinlock_lock(&task->lock);
  416.     atomic_inc(&task->refcount);
  417.     atomic_inc(&task->lifecount);
  418.     list_append(&t->th_link, &task->th_head);
  419.     spinlock_unlock(&task->lock);
  420.  
  421.     /*
  422.      * Register this thread in the system-wide list.
  423.      */
  424.     spinlock_lock(&threads_lock);
  425.     avltree_insert(&threads_tree, &t->threads_tree_node);
  426.     spinlock_unlock(&threads_lock);
  427.    
  428.     interrupts_restore(ipl);
  429. }
  430.  
  431. /** Terminate thread.
  432.  *
  433.  * End current thread execution and switch it to the exiting state. All pending
  434.  * timeouts are executed.
  435.  */
  436. void thread_exit(void)
  437. {
  438.     ipl_t ipl;
  439.  
  440.     if (atomic_predec(&TASK->lifecount) == 0) {
  441.         /*
  442.          * We are the last thread in the task that still has not exited.
  443.          * With the exception of the moment the task was created, new
  444.          * threads can only be created by threads of the same task.
  445.          * We are safe to perform cleanup.
  446.          */
  447.         if (THREAD->flags & THREAD_FLAG_USPACE) {
  448.             ipc_cleanup();
  449.             futex_cleanup();
  450.             LOG("Cleanup of task %" PRIu64" completed.", TASK->taskid);
  451.         }
  452.     }
  453.  
  454. restart:
  455.     ipl = interrupts_disable();
  456.     spinlock_lock(&THREAD->lock);
  457.     if (THREAD->timeout_pending) {
  458.         /* busy waiting for timeouts in progress */
  459.         spinlock_unlock(&THREAD->lock);
  460.         interrupts_restore(ipl);
  461.         goto restart;
  462.     }
  463.    
  464.     THREAD->state = Exiting;
  465.     spinlock_unlock(&THREAD->lock);
  466.     scheduler();
  467.  
  468.     /* Not reached */
  469.     while (1)
  470.         ;
  471. }
  472.  
  473.  
  474. /** Thread sleep
  475.  *
  476.  * Suspend execution of the current thread.
  477.  *
  478.  * @param sec Number of seconds to sleep.
  479.  *
  480.  */
  481. void thread_sleep(uint32_t sec)
  482. {
  483.     thread_usleep(sec * 1000000);
  484. }
  485.  
  486. /** Wait for another thread to exit.
  487.  *
  488.  * @param t Thread to join on exit.
  489.  * @param usec Timeout in microseconds.
  490.  * @param flags Mode of operation.
  491.  *
  492.  * @return An error code from errno.h or an error code from synch.h.
  493.  */
  494. int thread_join_timeout(thread_t *t, uint32_t usec, int flags)
  495. {
  496.     ipl_t ipl;
  497.     int rc;
  498.  
  499.     if (t == THREAD)
  500.         return EINVAL;
  501.  
  502.     /*
  503.      * Since thread join can only be called once on an undetached thread,
  504.      * the thread pointer is guaranteed to be still valid.
  505.      */
  506.    
  507.     ipl = interrupts_disable();
  508.     spinlock_lock(&t->lock);
  509.     ASSERT(!t->detached);
  510.     spinlock_unlock(&t->lock);
  511.     interrupts_restore(ipl);
  512.    
  513.     rc = waitq_sleep_timeout(&t->join_wq, usec, flags);
  514.    
  515.     return rc; 
  516. }
  517.  
  518. /** Detach thread.
  519.  *
  520.  * Mark the thread as detached, if the thread is already in the Lingering
  521.  * state, deallocate its resources.
  522.  *
  523.  * @param t Thread to be detached.
  524.  */
  525. void thread_detach(thread_t *t)
  526. {
  527.     ipl_t ipl;
  528.  
  529.     /*
  530.      * Since the thread is expected not to be already detached,
  531.      * pointer to it must be still valid.
  532.      */
  533.     ipl = interrupts_disable();
  534.     spinlock_lock(&t->lock);
  535.     ASSERT(!t->detached);
  536.     if (t->state == Lingering) {
  537.         thread_destroy(t);  /* unlocks &t->lock */
  538.         interrupts_restore(ipl);
  539.         return;
  540.     } else {
  541.         t->detached = true;
  542.     }
  543.     spinlock_unlock(&t->lock);
  544.     interrupts_restore(ipl);
  545. }
  546.  
  547. /** Thread usleep
  548.  *
  549.  * Suspend execution of the current thread.
  550.  *
  551.  * @param usec Number of microseconds to sleep.
  552.  *
  553.  */
  554. void thread_usleep(uint32_t usec)
  555. {
  556.     waitq_t wq;
  557.                  
  558.     waitq_initialize(&wq);
  559.  
  560.     (void) waitq_sleep_timeout(&wq, usec, SYNCH_FLAGS_NON_BLOCKING);
  561. }
  562.  
  563. /** Register thread out-of-context invocation
  564.  *
  565.  * Register a function and its argument to be executed
  566.  * on next context switch to the current thread.
  567.  *
  568.  * @param call_me      Out-of-context function.
  569.  * @param call_me_with Out-of-context function argument.
  570.  *
  571.  */
  572. void thread_register_call_me(void (* call_me)(void *), void *call_me_with)
  573. {
  574.     ipl_t ipl;
  575.    
  576.     ipl = interrupts_disable();
  577.     spinlock_lock(&THREAD->lock);
  578.     THREAD->call_me = call_me;
  579.     THREAD->call_me_with = call_me_with;
  580.     spinlock_unlock(&THREAD->lock);
  581.     interrupts_restore(ipl);
  582. }
  583.  
  584. static bool thread_walker(avltree_node_t *node, void *arg)
  585. {
  586.     thread_t *t = avltree_get_instance(node, thread_t, threads_tree_node);
  587.    
  588.     uint64_t cycles;
  589.     char suffix;
  590.     order(t->cycles, &cycles, &suffix);
  591.  
  592. #ifdef __32_BITS__
  593.     printf("%-6" PRIu64" %-10s %10p %-8s %10p %-3" PRIu32 " %10p %10p %9" PRIu64 "%c ",
  594.         t->tid, t->name, t, thread_states[t->state], t->task,
  595.         t->task->context, t->thread_code, t->kstack, cycles, suffix);
  596. #endif
  597.  
  598. #ifdef __64_BITS__
  599.     printf("%-6" PRIu64" %-10s %18p %-8s %18p %-3" PRIu32 " %18p %18p %9" PRIu64 "%c ",
  600.         t->tid, t->name, t, thread_states[t->state], t->task,
  601.         t->task->context, t->thread_code, t->kstack, cycles, suffix);
  602. #endif
  603.            
  604.     if (t->cpu)
  605.         printf("%-4u", t->cpu->id);
  606.     else
  607.         printf("none");
  608.            
  609.     if (t->state == Sleeping) {
  610. #ifdef __32_BITS__
  611.         printf(" %10p", t->sleep_queue);
  612. #endif
  613.  
  614. #ifdef __64_BITS__
  615.         printf(" %18p", t->sleep_queue);
  616. #endif
  617.     }
  618.            
  619.     printf("\n");
  620.  
  621.     return true;
  622. }
  623.  
  624. /** Print list of threads debug info */
  625. void thread_print_list(void)
  626. {
  627.     ipl_t ipl;
  628.    
  629.     /* Messing with thread structures, avoid deadlock */
  630.     ipl = interrupts_disable();
  631.     spinlock_lock(&threads_lock);
  632.  
  633. #ifdef __32_BITS__ 
  634.     printf("tid    name       address    state    task       "
  635.         "ctx code       stack      cycles     cpu  "
  636.         "waitqueue\n");
  637.     printf("------ ---------- ---------- -------- ---------- "
  638.         "--- ---------- ---------- ---------- ---- "
  639.         "----------\n");
  640. #endif
  641.  
  642. #ifdef __64_BITS__
  643.     printf("tid    name       address            state    task               "
  644.         "ctx code               stack              cycles     cpu  "
  645.         "waitqueue\n");
  646.     printf("------ ---------- ------------------ -------- ------------------ "
  647.         "--- ------------------ ------------------ ---------- ---- "
  648.         "------------------\n");
  649. #endif
  650.  
  651.     avltree_walk(&threads_tree, thread_walker, NULL);
  652.  
  653.     spinlock_unlock(&threads_lock);
  654.     interrupts_restore(ipl);
  655. }
  656.  
  657. /** Check whether thread exists.
  658.  *
  659.  * Note that threads_lock must be already held and
  660.  * interrupts must be already disabled.
  661.  *
  662.  * @param t Pointer to thread.
  663.  *
  664.  * @return True if thread t is known to the system, false otherwise.
  665.  */
  666. bool thread_exists(thread_t *t)
  667. {
  668.     avltree_node_t *node;
  669.  
  670.     node = avltree_search(&threads_tree, (avltree_key_t) ((uintptr_t) t));
  671.    
  672.     return node != NULL;
  673. }
  674.  
  675. /** Update accounting of current thread.
  676.  *
  677.  * Note that thread_lock on THREAD must be already held and
  678.  * interrupts must be already disabled.
  679.  *
  680.  */
  681. void thread_update_accounting(void)
  682. {
  683.     uint64_t time = get_cycle();
  684.     THREAD->cycles += time - THREAD->last_cycle;
  685.     THREAD->last_cycle = time;
  686. }
  687.  
  688. /** Process syscall to create new thread.
  689.  *
  690.  */
  691. unative_t sys_thread_create(uspace_arg_t *uspace_uarg, char *uspace_name,
  692.     thread_id_t *uspace_thread_id)
  693. {
  694.     thread_t *t;
  695.     char namebuf[THREAD_NAME_BUFLEN];
  696.     uspace_arg_t *kernel_uarg;
  697.     int rc;
  698.  
  699.     rc = copy_from_uspace(namebuf, uspace_name, THREAD_NAME_BUFLEN);
  700.     if (rc != 0)
  701.         return (unative_t) rc;
  702.  
  703.     /*
  704.      * In case of failure, kernel_uarg will be deallocated in this function.
  705.      * In case of success, kernel_uarg will be freed in uinit().
  706.      */
  707.     kernel_uarg = (uspace_arg_t *) malloc(sizeof(uspace_arg_t), 0);
  708.    
  709.     rc = copy_from_uspace(kernel_uarg, uspace_uarg, sizeof(uspace_arg_t));
  710.     if (rc != 0) {
  711.         free(kernel_uarg);
  712.         return (unative_t) rc;
  713.     }
  714.  
  715.     t = thread_create(uinit, kernel_uarg, TASK,
  716.         THREAD_FLAG_USPACE | THREAD_FLAG_NOATTACH, namebuf, false);
  717.     if (t) {
  718.         if (uspace_thread_id != NULL) {
  719.             int rc;
  720.  
  721.             rc = copy_to_uspace(uspace_thread_id, &t->tid,
  722.                 sizeof(t->tid));
  723.             if (rc != 0) {
  724.                 /*
  725.                  * We have encountered a failure, but the thread
  726.                  * has already been created. We need to undo its
  727.                  * creation now.
  728.                  */
  729.  
  730.                 /*
  731.                  * The new thread structure is initialized, but
  732.                  * is still not visible to the system.
  733.                  * We can safely deallocate it.
  734.                  */
  735.                 slab_free(thread_slab, t);
  736.                 free(kernel_uarg);
  737.  
  738.                 return (unative_t) rc;
  739.              }
  740.         }
  741.         thread_attach(t, TASK);
  742.         thread_ready(t);
  743.  
  744.         return 0;
  745.     } else
  746.         free(kernel_uarg);
  747.  
  748.     return (unative_t) ENOMEM;
  749. }
  750.  
  751. /** Process syscall to terminate thread.
  752.  *
  753.  */
  754. unative_t sys_thread_exit(int uspace_status)
  755. {
  756.     thread_exit();
  757.     /* Unreachable */
  758.     return 0;
  759. }
  760.  
  761. /** Syscall for getting TID.
  762.  *
  763.  * @param uspace_thread_id Userspace address of 8-byte buffer where to store
  764.  * current thread ID.
  765.  *
  766.  * @return 0 on success or an error code from @ref errno.h.
  767.  */
  768. unative_t sys_thread_get_id(thread_id_t *uspace_thread_id)
  769. {
  770.     /*
  771.      * No need to acquire lock on THREAD because tid
  772.      * remains constant for the lifespan of the thread.
  773.      */
  774.     return (unative_t) copy_to_uspace(uspace_thread_id, &THREAD->tid,
  775.         sizeof(THREAD->tid));
  776. }
  777.  
  778. /** @}
  779.  */
  780.