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3438 svoboda 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
3457 svoboda 35
 * @brief   Udebug hooks and data structure management.
3438 svoboda 36
 *
3457 svoboda 37
 * Udebug is an interface that makes userspace debuggers possible.
38
 *
3438 svoboda 39
 * Functions in this file are executed directly in each thread, which
40
 * may or may not be the subject of debugging. The udebug_stoppable_begin/end()
41
 * functions are also executed in the clock interrupt handler. To avoid
42
 * deadlock, functions in this file are protected from the interrupt
43
 * by locking the recursive lock THREAD->udebug.int_lock (just an atomic
44
 * variable). This prevents udebug_stoppable_begin/end() from being
45
 * executed in the interrupt handler (they are skipped).
46
 *
47
 * Functions in udebug_ops.c and udebug_ipc.c execute in different threads,
48
 * so they needn't be protected from the (preemptible) interrupt-initiated
49
 * code.
50
 */
51
 
52
#include <synch/waitq.h>
3441 svoboda 53
#include <debug.h>
3438 svoboda 54
#include <udebug/udebug.h>
55
#include <errno.h>
56
#include <arch.h>
57
 
58
static inline void udebug_int_lock(void)
59
{
60
    atomic_inc(&THREAD->udebug.int_lock);
61
}
62
 
63
static inline void udebug_int_unlock(void)
64
{
65
    atomic_dec(&THREAD->udebug.int_lock);
66
}
67
 
3457 svoboda 68
/** Initialize udebug part of task structure.
69
 *
70
 * Called as part of task structure initialization.
71
 * @param ut    Pointer to the structure to initialize.
72
 */
3438 svoboda 73
void udebug_task_init(udebug_task_t *ut)
74
{
75
    mutex_initialize(&ut->lock, MUTEX_PASSIVE);
76
    ut->dt_state = UDEBUG_TS_INACTIVE;
77
    ut->begin_call = NULL;
78
    ut->not_stoppable_count = 0;
79
    ut->evmask = 0;
80
}
81
 
3457 svoboda 82
/** Initialize udebug part of thread structure.
83
 *
84
 * Called as part of thread structure initialization.
85
 * @param ut    Pointer to the structure to initialize.
86
 */
3438 svoboda 87
void udebug_thread_initialize(udebug_thread_t *ut)
88
{
89
    mutex_initialize(&ut->lock, MUTEX_PASSIVE);
90
    waitq_initialize(&ut->go_wq);
91
 
92
    /*
93
     * At the beginning the thread is stoppable, so int_lock be set, too.
94
     */
95
    atomic_set(&ut->int_lock, 1);
96
 
97
    ut->go_call = NULL;
3602 rimsky 98
    ut->go = false;
3438 svoboda 99
    ut->stoppable = true;
100
    ut->debug_active = false;
101
    ut->cur_event = 0; /* none */
102
}
103
 
3457 svoboda 104
/** Wait for a GO message.
105
 *
106
 * When a debugging event occurs in a thread or the thread is stopped,
107
 * this function is called to block the thread until a GO message
108
 * is received.
109
 *
110
 * @param wq    The wait queue used by the thread to wait for GO messages.
111
 */
3438 svoboda 112
static void udebug_wait_for_go(waitq_t *wq)
113
{
114
    int rc;
115
    ipl_t ipl;
116
 
117
    ipl = waitq_sleep_prepare(wq);
118
 
119
    wq->missed_wakeups = 0; /* Enforce blocking. */
120
    rc = waitq_sleep_timeout_unsafe(wq, SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE);
121
 
122
    waitq_sleep_finish(wq, rc, ipl);
123
}
124
 
125
/** Do a preliminary check that a debugging session is in progress.
126
 *
3457 svoboda 127
 * This only requires the THREAD->udebug.lock mutex (and not TASK->udebug.lock
128
 * mutex). For an undebugged task, this will never block (while there could be
129
 * collisions by different threads on the TASK mutex), thus improving SMP
130
 * perormance for undebugged tasks.
131
 *
132
 * @return  True if the thread was in a debugging session when the function
133
 *      checked, false otherwise.
3438 svoboda 134
 */
135
static bool udebug_thread_precheck(void)
136
{
137
    bool res;
138
 
139
    mutex_lock(&THREAD->udebug.lock);
140
    res = THREAD->udebug.debug_active;
141
    mutex_unlock(&THREAD->udebug.lock);
142
 
143
    return res;
144
}
145
 
3457 svoboda 146
/** Start of stoppable section.
147
 *
148
 * A stoppable section is a section of code where if the thread can be stoped. In other words,
149
 * if a STOP operation is issued, the thread is guaranteed not to execute
150
 * any userspace instructions until the thread is resumed.
151
 *
152
 * Having stoppable sections is better than having stopping points, since
153
 * a thread can be stopped even when it is blocked indefinitely in a system
154
 * call (whereas it would not reach any stopping point).
155
 */
3438 svoboda 156
void udebug_stoppable_begin(void)
157
{
158
    int nsc;
159
    call_t *db_call, *go_call;
160
 
161
    ASSERT(THREAD);
162
    ASSERT(TASK);
163
 
164
    udebug_int_lock();
165
 
166
    /* Early check for undebugged tasks */
167
    if (!udebug_thread_precheck()) {
168
        udebug_int_unlock();
169
        return;
170
    }
171
 
172
    mutex_lock(&TASK->udebug.lock);
173
 
174
    nsc = --TASK->udebug.not_stoppable_count;
175
 
176
    /* Lock order OK, THREAD->udebug.lock is after TASK->udebug.lock */
177
    mutex_lock(&THREAD->udebug.lock);
178
    ASSERT(THREAD->udebug.stoppable == false);
179
    THREAD->udebug.stoppable = true;
180
 
181
    if (TASK->udebug.dt_state == UDEBUG_TS_BEGINNING && nsc == 0) {
182
        /*
183
         * This was the last non-stoppable thread. Reply to
184
         * DEBUG_BEGIN call.
185
         */
186
 
187
        db_call = TASK->udebug.begin_call;
188
        ASSERT(db_call);
189
 
190
        TASK->udebug.dt_state = UDEBUG_TS_ACTIVE;
191
        TASK->udebug.begin_call = NULL;
192
 
193
        IPC_SET_RETVAL(db_call->data, 0);
194
        ipc_answer(&TASK->answerbox, db_call);     
195
 
196
    } else if (TASK->udebug.dt_state == UDEBUG_TS_ACTIVE) {
197
        /*
198
         * Active debugging session
199
         */
200
 
3602 rimsky 201
        if (THREAD->udebug.debug_active == true &&
202
            THREAD->udebug.go == false) {
3438 svoboda 203
            /*
204
             * Thread was requested to stop - answer go call
205
             */
206
 
207
            /* Make sure nobody takes this call away from us */
208
            go_call = THREAD->udebug.go_call;
209
            THREAD->udebug.go_call = NULL;
210
            ASSERT(go_call);
211
 
212
            IPC_SET_RETVAL(go_call->data, 0);
213
            IPC_SET_ARG1(go_call->data, UDEBUG_EVENT_STOP);
214
 
215
            THREAD->udebug.cur_event = UDEBUG_EVENT_STOP;
216
 
217
                ipc_answer(&TASK->answerbox, go_call);
218
        }
219
    }
220
 
221
    mutex_unlock(&THREAD->udebug.lock);
222
        mutex_unlock(&TASK->udebug.lock);
223
}
224
 
3457 svoboda 225
/** End of a stoppable section.
226
 *
227
 * This is the point where the thread will block if it is stopped.
228
 * (As, by definition, a stopped thread must not leave its stoppable section).
229
 */
3438 svoboda 230
void udebug_stoppable_end(void)
231
{
232
    /* Early check for undebugged tasks */
233
    if (!udebug_thread_precheck()) {
234
        udebug_int_unlock();
235
        return;
236
    }
237
 
238
restart:
239
    mutex_lock(&TASK->udebug.lock);
240
    mutex_lock(&THREAD->udebug.lock);
241
 
242
    if (THREAD->udebug.debug_active &&
3602 rimsky 243
        THREAD->udebug.go == false) {
3438 svoboda 244
        TASK->udebug.begin_call = NULL;
245
        mutex_unlock(&THREAD->udebug.lock);
246
        mutex_unlock(&TASK->udebug.lock);
247
 
248
        udebug_wait_for_go(&THREAD->udebug.go_wq);
249
 
250
        goto restart;
3602 rimsky 251
        /* Must try again - have to lose stoppability atomically. */
3438 svoboda 252
    } else {
253
        ++TASK->udebug.not_stoppable_count;
254
        ASSERT(THREAD->udebug.stoppable == true);
255
        THREAD->udebug.stoppable = false;
256
 
257
        mutex_unlock(&THREAD->udebug.lock);
258
        mutex_unlock(&TASK->udebug.lock);
259
    }
260
 
261
    udebug_int_unlock();
262
}
263
 
264
/** Upon being scheduled to run, check if the current thread should stop.
265
 *
266
 * This function is called from clock(). Preemption is enabled.
267
 * interrupts are disabled, but since this is called after
268
 * being scheduled-in, we can enable them, if we're careful enough
269
 * not to allow arbitrary recursion or deadlock with the thread context.
270
 */
271
void udebug_before_thread_runs(void)
272
{
273
    ipl_t ipl;
274
 
275
    return;
276
    ASSERT(!PREEMPTION_DISABLED);
277
 
278
    /*
279
     * Prevent agains re-entering, such as when preempted inside this
280
     * function.
281
     */
282
    if (atomic_get(&THREAD->udebug.int_lock) != 0)
283
        return;
284
 
285
    udebug_int_lock();
286
 
287
    ipl = interrupts_enable();
288
 
289
    /* Now we're free to do whatever we need (lock mutexes, sleep, etc.) */
290
 
291
    /* Check if we're supposed to stop */
292
    udebug_stoppable_begin();
293
    udebug_stoppable_end();
294
 
295
    interrupts_restore(ipl);
296
 
297
    udebug_int_unlock();
298
}
299
 
3457 svoboda 300
/** Syscall event hook.
301
 *
302
 * Must be called before and after servicing a system call. This generates
303
 * a SYSCALL_B or SYSCALL_E event, depending on the value of @a end_variant.
304
 */
3438 svoboda 305
void udebug_syscall_event(unative_t a1, unative_t a2, unative_t a3,
306
    unative_t a4, unative_t a5, unative_t a6, unative_t id, unative_t rc,
307
    bool end_variant)
308
{
309
    call_t *call;
310
    udebug_event_t etype;
311
 
312
    etype = end_variant ? UDEBUG_EVENT_SYSCALL_E : UDEBUG_EVENT_SYSCALL_B;
313
 
314
    udebug_int_lock();
315
 
316
    /* Early check for undebugged tasks */
317
    if (!udebug_thread_precheck()) {
318
        udebug_int_unlock();
319
        return;
320
    }
321
 
322
    mutex_lock(&TASK->udebug.lock);
323
    mutex_lock(&THREAD->udebug.lock);
324
 
3602 rimsky 325
    /* Must only generate events when in debugging session and is go. */
3438 svoboda 326
    if (THREAD->udebug.debug_active != true ||
3602 rimsky 327
        THREAD->udebug.go == false ||
3438 svoboda 328
        (TASK->udebug.evmask & UDEBUG_EVMASK(etype)) == 0) {
329
        mutex_unlock(&THREAD->udebug.lock);
330
        mutex_unlock(&TASK->udebug.lock);
331
        return;
332
    }
333
 
334
    //printf("udebug_syscall_event\n");
335
    call = THREAD->udebug.go_call;
336
    THREAD->udebug.go_call = NULL;
337
 
338
    IPC_SET_RETVAL(call->data, 0);
339
    IPC_SET_ARG1(call->data, etype);
340
    IPC_SET_ARG2(call->data, id);
341
    IPC_SET_ARG3(call->data, rc);
342
    //printf("udebug_syscall_event/ipc_answer\n");
343
 
344
    THREAD->udebug.syscall_args[0] = a1;
345
    THREAD->udebug.syscall_args[1] = a2;
346
    THREAD->udebug.syscall_args[2] = a3;
347
    THREAD->udebug.syscall_args[3] = a4;
348
    THREAD->udebug.syscall_args[4] = a5;
349
    THREAD->udebug.syscall_args[5] = a6;
350
 
351
    /*
3602 rimsky 352
     * Make sure udebug.go is false when going to sleep
3438 svoboda 353
     * in case we get woken up by DEBUG_END. (At which
354
     * point it must be back to the initial true value).
355
     */
3602 rimsky 356
    THREAD->udebug.go = false;
3438 svoboda 357
    THREAD->udebug.cur_event = etype;
358
 
359
    ipc_answer(&TASK->answerbox, call);
360
 
361
    mutex_unlock(&THREAD->udebug.lock);
362
    mutex_unlock(&TASK->udebug.lock);
363
 
364
    udebug_wait_for_go(&THREAD->udebug.go_wq);
365
 
366
    udebug_int_unlock();
367
}
368
 
3457 svoboda 369
/** Thread-creation event hook.
370
 *
371
 * Must be called when a new userspace thread is created in the debugged
372
 * task. Generates a THREAD_B event.
373
 *
374
 * @param t Structure of the thread being created. Not locked, as the
375
 *      thread is not executing yet.
376
 */
3438 svoboda 377
void udebug_thread_b_event(struct thread *t)
378
{
379
    call_t *call;
380
 
381
    udebug_int_lock();
382
 
383
    mutex_lock(&TASK->udebug.lock);
384
    mutex_lock(&THREAD->udebug.lock);
385
 
3441 svoboda 386
    LOG("udebug_thread_b_event\n");
387
    LOG("- check state\n");
3438 svoboda 388
 
389
    /* Must only generate events when in debugging session */
390
    if (THREAD->udebug.debug_active != true) {
3602 rimsky 391
        LOG("- debug_active: %s, udebug.go: %s\n",
3438 svoboda 392
            THREAD->udebug.debug_active ? "yes(+)" : "no(-)",
3602 rimsky 393
            THREAD->udebug.go ? "yes(-)" : "no(+)");
3438 svoboda 394
        mutex_unlock(&THREAD->udebug.lock);
395
        mutex_unlock(&TASK->udebug.lock);
396
        return;
397
    }
398
 
3441 svoboda 399
    LOG("- trigger event\n");
3438 svoboda 400
 
401
    call = THREAD->udebug.go_call;
402
    THREAD->udebug.go_call = NULL;
403
    IPC_SET_RETVAL(call->data, 0);
404
    IPC_SET_ARG1(call->data, UDEBUG_EVENT_THREAD_B);
405
    IPC_SET_ARG2(call->data, (unative_t)t);
406
 
407
    /*
3602 rimsky 408
     * Make sure udebug.go is false when going to sleep
3438 svoboda 409
     * in case we get woken up by DEBUG_END. (At which
410
     * point it must be back to the initial true value).
411
     */
3602 rimsky 412
    THREAD->udebug.go = false;
3438 svoboda 413
    THREAD->udebug.cur_event = UDEBUG_EVENT_THREAD_B;
414
 
415
    ipc_answer(&TASK->answerbox, call);
416
 
417
    mutex_unlock(&THREAD->udebug.lock);
418
    mutex_unlock(&TASK->udebug.lock);
419
 
3441 svoboda 420
    LOG("- sleep\n");
3438 svoboda 421
    udebug_wait_for_go(&THREAD->udebug.go_wq);
422
 
423
    udebug_int_unlock();
424
}
425
 
3457 svoboda 426
/** Thread-termination event hook.
427
 *
428
 * Must be called when the current thread is terminating.
429
 * Generates a THREAD_E event.
430
 */
3438 svoboda 431
void udebug_thread_e_event(void)
432
{
433
    call_t *call;
434
 
435
    udebug_int_lock();
436
 
437
    mutex_lock(&TASK->udebug.lock);
438
    mutex_lock(&THREAD->udebug.lock);
439
 
3441 svoboda 440
    LOG("udebug_thread_e_event\n");
441
    LOG("- check state\n");
3438 svoboda 442
 
3602 rimsky 443
    /* Must only generate events when in debugging session. */
3438 svoboda 444
    if (THREAD->udebug.debug_active != true) {
3602 rimsky 445
/*      printf("- debug_active: %s, udebug.go: %s\n",
3438 svoboda 446
            THREAD->udebug.debug_active ? "yes(+)" : "no(-)",
3602 rimsky 447
            THREAD->udebug.go ? "yes(-)" : "no(+)");*/
3438 svoboda 448
        mutex_unlock(&THREAD->udebug.lock);
449
        mutex_unlock(&TASK->udebug.lock);
450
        return;
451
    }
452
 
3441 svoboda 453
    LOG("- trigger event\n");
3438 svoboda 454
 
455
    call = THREAD->udebug.go_call;
456
    THREAD->udebug.go_call = NULL;
457
    IPC_SET_RETVAL(call->data, 0);
458
    IPC_SET_ARG1(call->data, UDEBUG_EVENT_THREAD_E);
459
 
3602 rimsky 460
    /* Prevent any further debug activity in thread. */
3438 svoboda 461
    THREAD->udebug.debug_active = false;
462
    THREAD->udebug.cur_event = 0;       /* none */
3602 rimsky 463
    THREAD->udebug.go = false;  /* set to initial value */
3438 svoboda 464
 
465
    ipc_answer(&TASK->answerbox, call);
466
 
467
    mutex_unlock(&THREAD->udebug.lock);
468
    mutex_unlock(&TASK->udebug.lock);
469
 
3602 rimsky 470
    /* Leave int_lock enabled. */
471
    /* This event does not sleep - debugging has finished in this thread. */
3438 svoboda 472
}
473
 
474
/**
475
 * Terminate task debugging session.
476
 *
3457 svoboda 477
 * Gracefully terminates the debugging session for a task. If the debugger
478
 * is still waiting for events on some threads, it will receive a
479
 * FINISHED event for each of them.
480
 *
481
 * @param ta    Task structure. ta->udebug.lock must be already locked.
482
 * @return  Zero on success or negative error code.
3438 svoboda 483
 */
484
int udebug_task_cleanup(struct task *ta)
485
{
486
    thread_t *t;
487
    link_t *cur;
488
    int flags;
489
    ipl_t ipl;
490
 
3441 svoboda 491
    LOG("udebug_task_cleanup()\n");
492
    LOG("task %" PRIu64 "\n", ta->taskid);
3438 svoboda 493
 
494
    udebug_int_lock();
495
 
496
    if (ta->udebug.dt_state != UDEBUG_TS_BEGINNING &&
497
        ta->udebug.dt_state != UDEBUG_TS_ACTIVE) {
3441 svoboda 498
        LOG("udebug_task_cleanup(): task not being debugged\n");
3438 svoboda 499
        return EINVAL;
500
    }
501
 
502
    /* Finish debugging of all userspace threads */
503
    for (cur = ta->th_head.next; cur != &ta->th_head; cur = cur->next) {
504
        t = list_get_instance(cur, thread_t, th_link);
505
 
506
        mutex_lock(&t->udebug.lock);
507
 
508
        ipl = interrupts_disable();
509
        spinlock_lock(&t->lock);
510
 
511
        flags = t->flags;
512
 
513
        spinlock_unlock(&t->lock);
514
        interrupts_restore(ipl);
515
 
3602 rimsky 516
        /* Only process userspace threads. */
3438 svoboda 517
        if ((flags & THREAD_FLAG_USPACE) != 0) {
3602 rimsky 518
            /* Prevent any further debug activity in thread. */
3438 svoboda 519
            t->udebug.debug_active = false;
520
            t->udebug.cur_event = 0;    /* none */
521
 
3602 rimsky 522
            /* Is the thread still go? */
523
            if (t->udebug.go == true) {
3438 svoboda 524
                /*
525
                * Yes, so clear go. As debug_active == false,
526
                 * this doesn't affect anything.
527
                 */
3602 rimsky 528
                t->udebug.go = false;  
3438 svoboda 529
 
530
                /* Answer GO call */
3441 svoboda 531
                LOG("answer GO call with EVENT_FINISHED\n");
3438 svoboda 532
                IPC_SET_RETVAL(t->udebug.go_call->data, 0);
3468 svoboda 533
                IPC_SET_ARG1(t->udebug.go_call->data,
534
                    UDEBUG_EVENT_FINISHED);
3438 svoboda 535
 
536
                ipc_answer(&ta->answerbox, t->udebug.go_call);
537
                t->udebug.go_call = NULL;
538
            } else {
539
                /*
540
                 * Debug_stop is already at initial value.
541
                 * Yet this means the thread needs waking up.
542
                 */
543
 
544
                /*
545
                 * t's lock must not be held when calling
546
                 * waitq_wakeup.
547
                 */
548
                waitq_wakeup(&t->udebug.go_wq, WAKEUP_FIRST);
549
            }
550
        }
551
        mutex_unlock(&t->udebug.lock);
552
    }
553
 
554
    ta->udebug.dt_state = UDEBUG_TS_INACTIVE;
555
    ta->udebug.debugger = NULL;
556
 
557
    udebug_int_unlock();
558
 
559
    return 0;
560
}
561
 
562
 
563
/** @}
564
 */