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