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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
3474 svoboda 35
 * @brief   Udebug hooks and data structure management.
3438 svoboda 36
 *
3474 svoboda 37
 * Udebug is an interface that makes userspace debuggers possible.
3438 svoboda 38
 */
39
 
40
#include <synch/waitq.h>
3441 svoboda 41
#include <debug.h>
3438 svoboda 42
#include <udebug/udebug.h>
43
#include <errno.h>
44
#include <arch.h>
45
 
46
 
3474 svoboda 47
/** Initialize udebug part of task structure.
48
 *
49
 * Called as part of task structure initialization.
50
 * @param ut    Pointer to the structure to initialize.
51
 */
3438 svoboda 52
void udebug_task_init(udebug_task_t *ut)
53
{
54
    mutex_initialize(&ut->lock, MUTEX_PASSIVE);
55
    ut->dt_state = UDEBUG_TS_INACTIVE;
56
    ut->begin_call = NULL;
57
    ut->not_stoppable_count = 0;
58
    ut->evmask = 0;
59
}
60
 
3474 svoboda 61
/** Initialize udebug part of thread structure.
62
 *
63
 * Called as part of thread structure initialization.
64
 * @param ut    Pointer to the structure to initialize.
65
 */
3438 svoboda 66
void udebug_thread_initialize(udebug_thread_t *ut)
67
{
68
    mutex_initialize(&ut->lock, MUTEX_PASSIVE);
69
    waitq_initialize(&ut->go_wq);
70
 
71
    ut->go_call = NULL;
3674 svoboda 72
    ut->uspace_state = NULL;
73
    ut->go = false;
3438 svoboda 74
    ut->stoppable = true;
4337 svoboda 75
    ut->active = false;
3438 svoboda 76
    ut->cur_event = 0; /* none */
77
}
78
 
3474 svoboda 79
/** Wait for a GO message.
80
 *
81
 * When a debugging event occurs in a thread or the thread is stopped,
82
 * this function is called to block the thread until a GO message
83
 * is received.
84
 *
85
 * @param wq    The wait queue used by the thread to wait for GO messages.
86
 */
3438 svoboda 87
static void udebug_wait_for_go(waitq_t *wq)
88
{
89
    int rc;
90
    ipl_t ipl;
91
 
92
    ipl = waitq_sleep_prepare(wq);
93
 
94
    wq->missed_wakeups = 0; /* Enforce blocking. */
95
    rc = waitq_sleep_timeout_unsafe(wq, SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE);
96
 
97
    waitq_sleep_finish(wq, rc, ipl);
98
}
99
 
100
/** Do a preliminary check that a debugging session is in progress.
101
 *
3474 svoboda 102
 * This only requires the THREAD->udebug.lock mutex (and not TASK->udebug.lock
103
 * mutex). For an undebugged task, this will never block (while there could be
104
 * collisions by different threads on the TASK mutex), thus improving SMP
105
 * perormance for undebugged tasks.
106
 *
107
 * @return  True if the thread was in a debugging session when the function
108
 *      checked, false otherwise.
3438 svoboda 109
 */
110
static bool udebug_thread_precheck(void)
111
{
112
    bool res;
113
 
114
    mutex_lock(&THREAD->udebug.lock);
4337 svoboda 115
    res = THREAD->udebug.active;
3438 svoboda 116
    mutex_unlock(&THREAD->udebug.lock);
117
 
118
    return res;
119
}
120
 
3474 svoboda 121
/** Start of stoppable section.
122
 *
123
 * A stoppable section is a section of code where if the thread can be stoped. In other words,
124
 * if a STOP operation is issued, the thread is guaranteed not to execute
125
 * any userspace instructions until the thread is resumed.
126
 *
127
 * Having stoppable sections is better than having stopping points, since
128
 * a thread can be stopped even when it is blocked indefinitely in a system
129
 * call (whereas it would not reach any stopping point).
130
 */
3438 svoboda 131
void udebug_stoppable_begin(void)
132
{
133
    int nsc;
134
    call_t *db_call, *go_call;
135
 
136
    ASSERT(THREAD);
137
    ASSERT(TASK);
138
 
139
    /* Early check for undebugged tasks */
140
    if (!udebug_thread_precheck()) {
141
        return;
142
    }
143
 
144
    mutex_lock(&TASK->udebug.lock);
145
 
146
    nsc = --TASK->udebug.not_stoppable_count;
147
 
148
    /* Lock order OK, THREAD->udebug.lock is after TASK->udebug.lock */
149
    mutex_lock(&THREAD->udebug.lock);
150
    ASSERT(THREAD->udebug.stoppable == false);
151
    THREAD->udebug.stoppable = true;
152
 
153
    if (TASK->udebug.dt_state == UDEBUG_TS_BEGINNING && nsc == 0) {
154
        /*
155
         * This was the last non-stoppable thread. Reply to
156
         * DEBUG_BEGIN call.
157
         */
158
 
159
        db_call = TASK->udebug.begin_call;
160
        ASSERT(db_call);
161
 
162
        TASK->udebug.dt_state = UDEBUG_TS_ACTIVE;
163
        TASK->udebug.begin_call = NULL;
164
 
165
        IPC_SET_RETVAL(db_call->data, 0);
166
        ipc_answer(&TASK->answerbox, db_call);     
167
 
168
    } else if (TASK->udebug.dt_state == UDEBUG_TS_ACTIVE) {
169
        /*
170
         * Active debugging session
171
         */
172
 
4337 svoboda 173
        if (THREAD->udebug.active == true &&
3674 svoboda 174
            THREAD->udebug.go == false) {
3438 svoboda 175
            /*
176
             * Thread was requested to stop - answer go call
177
             */
178
 
179
            /* Make sure nobody takes this call away from us */
180
            go_call = THREAD->udebug.go_call;
181
            THREAD->udebug.go_call = NULL;
182
            ASSERT(go_call);
183
 
184
            IPC_SET_RETVAL(go_call->data, 0);
185
            IPC_SET_ARG1(go_call->data, UDEBUG_EVENT_STOP);
186
 
187
            THREAD->udebug.cur_event = UDEBUG_EVENT_STOP;
188
 
189
                ipc_answer(&TASK->answerbox, go_call);
190
        }
191
    }
192
 
193
    mutex_unlock(&THREAD->udebug.lock);
194
        mutex_unlock(&TASK->udebug.lock);
195
}
196
 
3474 svoboda 197
/** End of a stoppable section.
198
 *
199
 * This is the point where the thread will block if it is stopped.
200
 * (As, by definition, a stopped thread must not leave its stoppable section).
201
 */
3438 svoboda 202
void udebug_stoppable_end(void)
203
{
204
    /* Early check for undebugged tasks */
205
    if (!udebug_thread_precheck()) {
206
        return;
207
    }
208
 
209
restart:
210
    mutex_lock(&TASK->udebug.lock);
211
    mutex_lock(&THREAD->udebug.lock);
212
 
4337 svoboda 213
    if (THREAD->udebug.active && THREAD->udebug.go == false) {
3438 svoboda 214
        TASK->udebug.begin_call = NULL;
215
        mutex_unlock(&THREAD->udebug.lock);
216
        mutex_unlock(&TASK->udebug.lock);
217
 
218
        udebug_wait_for_go(&THREAD->udebug.go_wq);
219
 
220
        goto restart;
3674 svoboda 221
        /* Must try again - have to lose stoppability atomically. */
3438 svoboda 222
    } else {
223
        ++TASK->udebug.not_stoppable_count;
224
        ASSERT(THREAD->udebug.stoppable == true);
225
        THREAD->udebug.stoppable = false;
226
 
227
        mutex_unlock(&THREAD->udebug.lock);
228
        mutex_unlock(&TASK->udebug.lock);
229
    }
230
}
231
 
232
/** Upon being scheduled to run, check if the current thread should stop.
233
 *
3674 svoboda 234
 * This function is called from clock().
3438 svoboda 235
 */
236
void udebug_before_thread_runs(void)
237
{
238
    /* Check if we're supposed to stop */
239
    udebug_stoppable_begin();
240
    udebug_stoppable_end();
241
}
242
 
3474 svoboda 243
/** Syscall event hook.
244
 *
245
 * Must be called before and after servicing a system call. This generates
246
 * a SYSCALL_B or SYSCALL_E event, depending on the value of @a end_variant.
247
 */
3438 svoboda 248
void udebug_syscall_event(unative_t a1, unative_t a2, unative_t a3,
249
    unative_t a4, unative_t a5, unative_t a6, unative_t id, unative_t rc,
250
    bool end_variant)
251
{
252
    call_t *call;
253
    udebug_event_t etype;
254
 
255
    etype = end_variant ? UDEBUG_EVENT_SYSCALL_E : UDEBUG_EVENT_SYSCALL_B;
256
 
257
    /* Early check for undebugged tasks */
258
    if (!udebug_thread_precheck()) {
259
        return;
260
    }
261
 
262
    mutex_lock(&TASK->udebug.lock);
263
    mutex_lock(&THREAD->udebug.lock);
264
 
3674 svoboda 265
    /* Must only generate events when in debugging session and is go. */
4337 svoboda 266
    if (THREAD->udebug.active != true || THREAD->udebug.go == false ||
3438 svoboda 267
        (TASK->udebug.evmask & UDEBUG_EVMASK(etype)) == 0) {
268
        mutex_unlock(&THREAD->udebug.lock);
269
        mutex_unlock(&TASK->udebug.lock);
270
        return;
271
    }
272
 
273
    //printf("udebug_syscall_event\n");
274
    call = THREAD->udebug.go_call;
275
    THREAD->udebug.go_call = NULL;
276
 
277
    IPC_SET_RETVAL(call->data, 0);
278
    IPC_SET_ARG1(call->data, etype);
279
    IPC_SET_ARG2(call->data, id);
280
    IPC_SET_ARG3(call->data, rc);
281
    //printf("udebug_syscall_event/ipc_answer\n");
282
 
283
    THREAD->udebug.syscall_args[0] = a1;
284
    THREAD->udebug.syscall_args[1] = a2;
285
    THREAD->udebug.syscall_args[2] = a3;
286
    THREAD->udebug.syscall_args[3] = a4;
287
    THREAD->udebug.syscall_args[4] = a5;
288
    THREAD->udebug.syscall_args[5] = a6;
289
 
290
    /*
3674 svoboda 291
     * Make sure udebug.go is false when going to sleep
3438 svoboda 292
     * in case we get woken up by DEBUG_END. (At which
293
     * point it must be back to the initial true value).
294
     */
3674 svoboda 295
    THREAD->udebug.go = false;
3438 svoboda 296
    THREAD->udebug.cur_event = etype;
297
 
298
    ipc_answer(&TASK->answerbox, call);
299
 
300
    mutex_unlock(&THREAD->udebug.lock);
301
    mutex_unlock(&TASK->udebug.lock);
302
 
303
    udebug_wait_for_go(&THREAD->udebug.go_wq);
304
}
305
 
3674 svoboda 306
/** Thread-creation event hook combined with attaching the thread.
3474 svoboda 307
 *
308
 * Must be called when a new userspace thread is created in the debugged
3674 svoboda 309
 * task. Generates a THREAD_B event. Also attaches the thread @a t
310
 * to the task @a ta.
3474 svoboda 311
 *
3674 svoboda 312
 * This is necessary to avoid a race condition where the BEGIN and THREAD_READ
313
 * requests would be handled inbetween attaching the thread and checking it
314
 * for being in a debugging session to send the THREAD_B event. We could then
315
 * either miss threads or get some threads both in the thread list
316
 * and get a THREAD_B event for them.
317
 *
3474 svoboda 318
 * @param t Structure of the thread being created. Not locked, as the
319
 *      thread is not executing yet.
3674 svoboda 320
 * @param ta    Task to which the thread should be attached.
3474 svoboda 321
 */
3674 svoboda 322
void udebug_thread_b_event_attach(struct thread *t, struct task *ta)
3438 svoboda 323
{
324
    call_t *call;
325
 
326
    mutex_lock(&TASK->udebug.lock);
327
    mutex_lock(&THREAD->udebug.lock);
328
 
3674 svoboda 329
    thread_attach(t, ta);
330
 
3441 svoboda 331
    LOG("udebug_thread_b_event\n");
332
    LOG("- check state\n");
3438 svoboda 333
 
334
    /* Must only generate events when in debugging session */
4337 svoboda 335
    if (THREAD->udebug.active != true) {
336
        LOG("- udebug.active: %s, udebug.go: %s\n",
337
            THREAD->udebug.active ? "yes(+)" : "no(-)",
3674 svoboda 338
            THREAD->udebug.go ? "yes(-)" : "no(+)");
3438 svoboda 339
        mutex_unlock(&THREAD->udebug.lock);
340
        mutex_unlock(&TASK->udebug.lock);
341
        return;
342
    }
343
 
3441 svoboda 344
    LOG("- trigger event\n");
3438 svoboda 345
 
346
    call = THREAD->udebug.go_call;
347
    THREAD->udebug.go_call = NULL;
348
    IPC_SET_RETVAL(call->data, 0);
349
    IPC_SET_ARG1(call->data, UDEBUG_EVENT_THREAD_B);
350
    IPC_SET_ARG2(call->data, (unative_t)t);
351
 
352
    /*
3674 svoboda 353
     * Make sure udebug.go is false when going to sleep
3438 svoboda 354
     * in case we get woken up by DEBUG_END. (At which
355
     * point it must be back to the initial true value).
356
     */
3674 svoboda 357
    THREAD->udebug.go = false;
3438 svoboda 358
    THREAD->udebug.cur_event = UDEBUG_EVENT_THREAD_B;
359
 
360
    ipc_answer(&TASK->answerbox, call);
361
 
362
    mutex_unlock(&THREAD->udebug.lock);
363
    mutex_unlock(&TASK->udebug.lock);
364
 
3441 svoboda 365
    LOG("- sleep\n");
3438 svoboda 366
    udebug_wait_for_go(&THREAD->udebug.go_wq);
367
}
368
 
3474 svoboda 369
/** Thread-termination event hook.
370
 *
371
 * Must be called when the current thread is terminating.
372
 * Generates a THREAD_E event.
373
 */
3438 svoboda 374
void udebug_thread_e_event(void)
375
{
376
    call_t *call;
377
 
378
    mutex_lock(&TASK->udebug.lock);
379
    mutex_lock(&THREAD->udebug.lock);
380
 
3441 svoboda 381
    LOG("udebug_thread_e_event\n");
382
    LOG("- check state\n");
3438 svoboda 383
 
3674 svoboda 384
    /* Must only generate events when in debugging session. */
4337 svoboda 385
    if (THREAD->udebug.active != true) {
386
/*      printf("- udebug.active: %s, udebug.go: %s\n",
387
            THREAD->udebug.active ? "yes(+)" : "no(-)",
3674 svoboda 388
            THREAD->udebug.go ? "yes(-)" : "no(+)");*/
3438 svoboda 389
        mutex_unlock(&THREAD->udebug.lock);
390
        mutex_unlock(&TASK->udebug.lock);
391
        return;
392
    }
393
 
3441 svoboda 394
    LOG("- trigger event\n");
3438 svoboda 395
 
396
    call = THREAD->udebug.go_call;
397
    THREAD->udebug.go_call = NULL;
398
    IPC_SET_RETVAL(call->data, 0);
399
    IPC_SET_ARG1(call->data, UDEBUG_EVENT_THREAD_E);
400
 
3674 svoboda 401
    /* Prevent any further debug activity in thread. */
4337 svoboda 402
    THREAD->udebug.active = false;
3438 svoboda 403
    THREAD->udebug.cur_event = 0;       /* none */
3674 svoboda 404
    THREAD->udebug.go = false;  /* set to initial value */
3438 svoboda 405
 
406
    ipc_answer(&TASK->answerbox, call);
407
 
408
    mutex_unlock(&THREAD->udebug.lock);
409
    mutex_unlock(&TASK->udebug.lock);
410
 
3674 svoboda 411
    /*
412
     * This event does not sleep - debugging has finished
413
     * in this thread.
414
     */
3438 svoboda 415
}
416
 
417
/**
418
 * Terminate task debugging session.
419
 *
3474 svoboda 420
 * Gracefully terminates the debugging session for a task. If the debugger
421
 * is still waiting for events on some threads, it will receive a
422
 * FINISHED event for each of them.
423
 *
424
 * @param ta    Task structure. ta->udebug.lock must be already locked.
425
 * @return  Zero on success or negative error code.
3438 svoboda 426
 */
427
int udebug_task_cleanup(struct task *ta)
428
{
429
    thread_t *t;
430
    link_t *cur;
431
    int flags;
432
    ipl_t ipl;
433
 
3441 svoboda 434
    LOG("udebug_task_cleanup()\n");
435
    LOG("task %" PRIu64 "\n", ta->taskid);
3438 svoboda 436
 
437
    if (ta->udebug.dt_state != UDEBUG_TS_BEGINNING &&
438
        ta->udebug.dt_state != UDEBUG_TS_ACTIVE) {
3441 svoboda 439
        LOG("udebug_task_cleanup(): task not being debugged\n");
3438 svoboda 440
        return EINVAL;
441
    }
442
 
443
    /* Finish debugging of all userspace threads */
444
    for (cur = ta->th_head.next; cur != &ta->th_head; cur = cur->next) {
445
        t = list_get_instance(cur, thread_t, th_link);
446
 
447
        mutex_lock(&t->udebug.lock);
448
 
449
        ipl = interrupts_disable();
450
        spinlock_lock(&t->lock);
451
 
452
        flags = t->flags;
453
 
454
        spinlock_unlock(&t->lock);
455
        interrupts_restore(ipl);
456
 
3674 svoboda 457
        /* Only process userspace threads. */
3438 svoboda 458
        if ((flags & THREAD_FLAG_USPACE) != 0) {
3674 svoboda 459
            /* Prevent any further debug activity in thread. */
4337 svoboda 460
            t->udebug.active = false;
3438 svoboda 461
            t->udebug.cur_event = 0;    /* none */
462
 
3674 svoboda 463
            /* Is the thread still go? */
464
            if (t->udebug.go == true) {
3438 svoboda 465
                /*
4337 svoboda 466
                * Yes, so clear go. As active == false,
3438 svoboda 467
                 * this doesn't affect anything.
468
                 */
3674 svoboda 469
                t->udebug.go = false;  
3438 svoboda 470
 
471
                /* Answer GO call */
3441 svoboda 472
                LOG("answer GO call with EVENT_FINISHED\n");
3438 svoboda 473
                IPC_SET_RETVAL(t->udebug.go_call->data, 0);
3474 svoboda 474
                IPC_SET_ARG1(t->udebug.go_call->data,
475
                    UDEBUG_EVENT_FINISHED);
3438 svoboda 476
 
477
                ipc_answer(&ta->answerbox, t->udebug.go_call);
478
                t->udebug.go_call = NULL;
479
            } else {
480
                /*
481
                 * Debug_stop is already at initial value.
482
                 * Yet this means the thread needs waking up.
483
                 */
484
 
485
                /*
486
                 * t's lock must not be held when calling
487
                 * waitq_wakeup.
488
                 */
489
                waitq_wakeup(&t->udebug.go_wq, WAKEUP_FIRST);
490
            }
491
        }
492
        mutex_unlock(&t->udebug.lock);
493
    }
494
 
495
    ta->udebug.dt_state = UDEBUG_TS_INACTIVE;
496
    ta->udebug.debugger = NULL;
497
 
498
    return 0;
499
}
500
 
501
 
502
/** @}
503
 */