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  1. /*
  2.  * Copyright (c) 2008 Jiri Svoboda
  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 generic
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief   Udebug operations.
  36.  */
  37.  
  38. #include <debug.h>
  39. #include <proc/task.h>
  40. #include <proc/thread.h>
  41. #include <arch.h>
  42. #include <errno.h>
  43. #include <syscall/copy.h>
  44. #include <ipc/ipc.h>
  45. #include <udebug/udebug.h>
  46. #include <udebug/udebug_ops.h>
  47.  
  48. /**
  49.  * Prepare a thread for a debugging operation.
  50.  *
  51.  * Simply put, return thread t with t->udebug.lock held,
  52.  * but only if it verifies all conditions.
  53.  *
  54.  * Specifically, verifies that thread t exists, is a userspace thread,
  55.  * and belongs to the current task (TASK). Verifies, that the thread
  56.  * has (or hasn't) go according to having_go (typically false).
  57.  * It also locks t->udebug.lock, making sure that t->udebug.debug_active
  58.  * is true - that the thread is in a valid debugging session.
  59.  *
  60.  * With this verified and the t->udebug.lock mutex held, it is ensured
  61.  * that the thread cannot leave the debugging session, let alone cease
  62.  * to exist.
  63.  *
  64.  * In this function, holding the TASK->udebug.lock mutex prevents the
  65.  * thread from leaving the debugging session, while relaxing from
  66.  * the t->lock spinlock to the t->udebug.lock mutex.
  67.  *
  68.  * Returns EOK if all went well, or an error code otherwise.
  69.  */
  70. static int _thread_op_begin(thread_t *t, bool having_go)
  71. {
  72.     task_id_t taskid;
  73.     ipl_t ipl;
  74.  
  75.     taskid = TASK->taskid;
  76.  
  77.     mutex_lock(&TASK->udebug.lock);
  78.  
  79.     /* thread_exists() must be called with threads_lock held */
  80.     ipl = interrupts_disable();
  81.     spinlock_lock(&threads_lock);
  82.  
  83.     if (!thread_exists(t)) {
  84.         spinlock_unlock(&threads_lock);
  85.         interrupts_restore(ipl);
  86.         mutex_unlock(&TASK->udebug.lock);
  87.         return ENOENT;
  88.     }
  89.  
  90.     /* t->lock is enough to ensure the thread's existence */
  91.     spinlock_lock(&t->lock);
  92.     spinlock_unlock(&threads_lock);
  93.  
  94.     /* Verify that 't' is a userspace thread */
  95.     if ((t->flags & THREAD_FLAG_USPACE) == 0) {
  96.         /* It's not, deny its existence */
  97.         spinlock_unlock(&t->lock);
  98.         interrupts_restore(ipl);
  99.         mutex_unlock(&TASK->udebug.lock);
  100.         return ENOENT;
  101.     }
  102.  
  103.     /* Verify debugging state */
  104.     if (t->udebug.debug_active != true) {
  105.         /* Not in debugging session or undesired GO state */
  106.         spinlock_unlock(&t->lock);
  107.         interrupts_restore(ipl);
  108.         mutex_unlock(&TASK->udebug.lock);
  109.         return ENOENT;
  110.     }
  111.  
  112.     /*
  113.      * Since the thread has debug_active == true, TASK->udebug.lock
  114.      * is enough to ensure its existence and that debug_active remains
  115.      * true.
  116.      */
  117.     spinlock_unlock(&t->lock);
  118.     interrupts_restore(ipl);
  119.  
  120.     /* Only mutex TASK->udebug.lock left */
  121.    
  122.     /* Now verify that the thread belongs to the current task */
  123.     if (t->task != TASK) {
  124.         /* No such thread belonging this task*/
  125.         mutex_unlock(&TASK->udebug.lock);
  126.         return ENOENT;
  127.     }
  128.  
  129.     /*
  130.      * Now we need to grab the thread's debug lock for synchronization
  131.      * of the threads stoppability/stop state.
  132.      */
  133.     mutex_lock(&t->udebug.lock);
  134.  
  135.     /* The big task mutex is no longer needed */
  136.     mutex_unlock(&TASK->udebug.lock);
  137.  
  138.     if (!t->udebug.stop != having_go) {
  139.         /* Not in debugging session or undesired GO state */
  140.         mutex_unlock(&t->udebug.lock);
  141.         return EINVAL;
  142.     }
  143.  
  144.     /* Only t->udebug.lock left */
  145.  
  146.     return EOK; /* All went well */
  147. }
  148.  
  149.  
  150. static void _thread_op_end(thread_t *t)
  151. {
  152.     mutex_unlock(&t->udebug.lock);
  153. }
  154.  
  155. /**
  156.  * \return 0 (ok, but not done yet), 1 (done) or negative error code.
  157.  */
  158. int udebug_begin(call_t *call)
  159. {
  160.     int reply;
  161.  
  162.     thread_t *t;
  163.     link_t *cur;
  164.  
  165.     LOG("udebug_begin()\n");
  166.  
  167.     mutex_lock(&TASK->udebug.lock);
  168.     LOG("debugging task %llu\n", TASK->taskid);
  169.  
  170.     if (TASK->udebug.dt_state != UDEBUG_TS_INACTIVE) {
  171.         mutex_unlock(&TASK->udebug.lock);
  172.         LOG("udebug_begin(): busy error\n");
  173.  
  174.         return EBUSY;
  175.     }
  176.  
  177.     TASK->udebug.dt_state = UDEBUG_TS_BEGINNING;
  178.     TASK->udebug.begin_call = call;
  179.     TASK->udebug.debugger = call->sender;
  180.  
  181.     if (TASK->udebug.not_stoppable_count == 0) {
  182.         TASK->udebug.dt_state = UDEBUG_TS_ACTIVE;
  183.         TASK->udebug.begin_call = NULL;
  184.         reply = 1; /* immediate reply */
  185.     } else {
  186.         reply = 0; /* no reply */
  187.     }
  188.    
  189.     /* Set udebug.debug_active on all of the task's userspace threads */
  190.  
  191.     for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {
  192.         t = list_get_instance(cur, thread_t, th_link);
  193.  
  194.         mutex_lock(&t->udebug.lock);
  195.         if ((t->flags & THREAD_FLAG_USPACE) != 0)
  196.             t->udebug.debug_active = true;
  197.         mutex_unlock(&t->udebug.lock);
  198.     }
  199.  
  200.     mutex_unlock(&TASK->udebug.lock);
  201.  
  202.     LOG("udebug_begin() done (%s)\n",
  203.         reply ? "reply" : "stoppability wait");
  204.  
  205.     return reply;
  206. }
  207.  
  208. int udebug_end(void)
  209. {
  210.     int rc;
  211.  
  212.     LOG("udebug_end()\n");
  213.  
  214.     mutex_lock(&TASK->udebug.lock);
  215.     LOG("task %" PRIu64 "\n", TASK->taskid);
  216.  
  217.     rc = udebug_task_cleanup(TASK);
  218.  
  219.     mutex_unlock(&TASK->udebug.lock);
  220.  
  221.     return rc;
  222. }
  223.  
  224. int udebug_set_evmask(udebug_evmask_t mask)
  225. {
  226.     LOG("udebug_set_mask()\n");
  227.  
  228.     mutex_lock(&TASK->udebug.lock);
  229.  
  230.     if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
  231.         mutex_unlock(&TASK->udebug.lock);
  232.         LOG("udebug_set_mask(): not active debuging session\n");
  233.  
  234.         return EINVAL;
  235.     }
  236.  
  237.     TASK->udebug.evmask = mask;
  238.  
  239.     mutex_unlock(&TASK->udebug.lock);
  240.  
  241.     return 0;
  242. }
  243.  
  244.  
  245. int udebug_go(thread_t *t, call_t *call)
  246. {
  247.     int rc;
  248.  
  249.     /* On success, this will lock t->udebug.lock */
  250.     rc = _thread_op_begin(t, false);
  251.     if (rc != EOK) {
  252.         return rc;
  253.     }
  254.  
  255.     t->udebug.go_call = call;
  256.     t->udebug.stop = false;
  257.     t->udebug.cur_event = 0;    /* none */
  258.  
  259.     /*
  260.      * Neither t's lock nor threads_lock may be held during wakeup
  261.      */
  262.     waitq_wakeup(&t->udebug.go_wq, WAKEUP_FIRST);
  263.  
  264.     _thread_op_end(t);
  265.  
  266.     return 0;
  267. }
  268.  
  269. int udebug_stop(thread_t *t, call_t *call)
  270. {
  271.     int rc;
  272.  
  273.     LOG("udebug_stop()\n");
  274.     mutex_lock(&TASK->udebug.lock);
  275.  
  276.     /*
  277.      * On success, this will lock t->udebug.lock. Note that this makes sure
  278.      * the thread is not stopped.
  279.      */
  280.     rc = _thread_op_begin(t, true);
  281.     if (rc != EOK) {
  282.         return rc;
  283.     }
  284.  
  285.     /* Take GO away from the thread */
  286.     t->udebug.stop = true;
  287.  
  288.     if (!t->udebug.stoppable) {
  289.         /* Answer will be sent when the thread becomes stoppable */
  290.         _thread_op_end(t);
  291.         return 0;
  292.     }
  293.  
  294.     /*
  295.      * Answer GO call
  296.      */
  297.     LOG("udebug_stop - answering go call\n");
  298.  
  299.     /* Make sure nobody takes this call away from us */
  300.     call = t->udebug.go_call;
  301.     t->udebug.go_call = NULL;
  302.  
  303.     IPC_SET_RETVAL(call->data, 0);
  304.     IPC_SET_ARG1(call->data, UDEBUG_EVENT_STOP);
  305.     LOG("udebug_stop/ipc_answer\n");
  306.  
  307.     THREAD->udebug.cur_event = UDEBUG_EVENT_STOP;
  308.  
  309.     _thread_op_end(t);
  310.  
  311.     ipc_answer(&TASK->answerbox, call);
  312.     mutex_unlock(&TASK->udebug.lock);
  313.  
  314.     LOG("udebog_stop/done\n");
  315.     return 0;
  316. }
  317.  
  318. int udebug_thread_read(void **buffer, size_t buf_size, size_t *n)
  319. {
  320.     thread_t *t;
  321.     link_t *cur;
  322.     unative_t tid;
  323.     unsigned copied_ids;
  324.     ipl_t ipl;
  325.     unative_t *id_buffer;
  326.     int flags;
  327.     size_t max_ids;
  328.  
  329.     LOG("udebug_thread_read()\n");
  330.  
  331.     /* Allocate a buffer to hold thread IDs */
  332.     id_buffer = malloc(buf_size, 0);
  333.  
  334.     mutex_lock(&TASK->udebug.lock);
  335.  
  336.     /* Verify task state */
  337.     if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
  338.         mutex_unlock(&TASK->udebug.lock);
  339.         return EINVAL;
  340.     }
  341.  
  342.     ipl = interrupts_disable();
  343.     spinlock_lock(&TASK->lock);
  344.     /* Copy down the thread IDs */
  345.  
  346.     max_ids = buf_size / sizeof(unative_t);
  347.     copied_ids = 0;
  348.  
  349.     /* FIXME: make sure the thread isn't past debug shutdown... */
  350.     for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {
  351.         /* Do not write past end of buffer */
  352.         if (copied_ids >= max_ids) break;
  353.  
  354.         t = list_get_instance(cur, thread_t, th_link);
  355.  
  356.         spinlock_lock(&t->lock);
  357.         flags = t->flags;
  358.         spinlock_unlock(&t->lock);
  359.  
  360.         /* Not interested in kernel threads */
  361.         if ((flags & THREAD_FLAG_USPACE) != 0) {
  362.             /* Using thread struct pointer as identification hash */
  363.             tid = (unative_t) t;
  364.             id_buffer[copied_ids++] = tid;
  365.         }
  366.     }
  367.  
  368.     spinlock_unlock(&TASK->lock);
  369.     interrupts_restore(ipl);
  370.  
  371.     mutex_unlock(&TASK->udebug.lock);
  372.  
  373.     *buffer = id_buffer;
  374.     *n = copied_ids * sizeof(unative_t);
  375.  
  376.     return 0;
  377. }
  378.  
  379. int udebug_args_read(thread_t *t, void **buffer)
  380. {
  381.     int rc;
  382.     unative_t *arg_buffer;
  383.  
  384.     /* Prepare a buffer to hold the arguments */
  385.     arg_buffer = malloc(6 * sizeof(unative_t), 0);
  386.  
  387.     /* On success, this will lock t->udebug.lock */
  388.     rc = _thread_op_begin(t, false);
  389.     if (rc != EOK) {
  390.         return rc;
  391.     }
  392.  
  393.     /* Additionally we need to verify that we are inside a syscall */
  394.     if (t->udebug.cur_event != UDEBUG_EVENT_SYSCALL_B &&
  395.         t->udebug.cur_event != UDEBUG_EVENT_SYSCALL_E) {
  396.         _thread_op_end(t);
  397.         return EINVAL;
  398.     }
  399.  
  400.     /* Copy to a local buffer before releasing the lock */
  401.     memcpy(arg_buffer, t->udebug.syscall_args, 6 * sizeof(unative_t));
  402.  
  403.     _thread_op_end(t);
  404.  
  405.     *buffer = arg_buffer;
  406.     return 0;
  407. }
  408.  
  409. int udebug_mem_read(unative_t uspace_addr, size_t n, void **buffer)
  410. {
  411.     void *data_buffer;
  412.     int rc;
  413.  
  414.     /* Verify task state */
  415.     mutex_lock(&TASK->udebug.lock);
  416.  
  417.     if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
  418.         mutex_unlock(&TASK->udebug.lock);
  419.         return EBUSY;
  420.     }
  421.  
  422.     data_buffer = malloc(n, 0);
  423.  
  424.     /* NOTE: this is not strictly from a syscall... but that shouldn't
  425.      * be a problem */
  426.     rc = copy_from_uspace(data_buffer, (void *)uspace_addr, n);
  427.     mutex_unlock(&TASK->udebug.lock);
  428.  
  429.     if (rc != 0) return rc;
  430.  
  431.     *buffer = data_buffer;
  432.     return 0;
  433. }
  434.  
  435. /** @}
  436.  */
  437.