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