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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>
4342 svoboda 44
#include <print.h>
3438 svoboda 45
#include <arch.h>
46
 
47
 
3474 svoboda 48
/** Initialize udebug part of task structure.
49
 *
50
 * Called as part of task structure initialization.
51
 * @param ut    Pointer to the structure to initialize.
52
 */
3438 svoboda 53
void udebug_task_init(udebug_task_t *ut)
54
{
55
    mutex_initialize(&ut->lock, MUTEX_PASSIVE);
56
    ut->dt_state = UDEBUG_TS_INACTIVE;
57
    ut->begin_call = NULL;
58
    ut->not_stoppable_count = 0;
59
    ut->evmask = 0;
60
}
61
 
3474 svoboda 62
/** Initialize udebug part of thread structure.
63
 *
64
 * Called as part of thread structure initialization.
65
 * @param ut    Pointer to the structure to initialize.
66
 */
3438 svoboda 67
void udebug_thread_initialize(udebug_thread_t *ut)
68
{
69
    mutex_initialize(&ut->lock, MUTEX_PASSIVE);
70
    waitq_initialize(&ut->go_wq);
71
 
72
    ut->go_call = NULL;
3674 svoboda 73
    ut->uspace_state = NULL;
74
    ut->go = false;
3438 svoboda 75
    ut->stoppable = true;
4337 svoboda 76
    ut->active = false;
3438 svoboda 77
    ut->cur_event = 0; /* none */
78
}
79
 
3474 svoboda 80
/** Wait for a GO message.
81
 *
82
 * When a debugging event occurs in a thread or the thread is stopped,
83
 * this function is called to block the thread until a GO message
84
 * is received.
85
 *
86
 * @param wq    The wait queue used by the thread to wait for GO messages.
87
 */
3438 svoboda 88
static void udebug_wait_for_go(waitq_t *wq)
89
{
90
    int rc;
91
    ipl_t ipl;
92
 
93
    ipl = waitq_sleep_prepare(wq);
94
 
95
    wq->missed_wakeups = 0; /* Enforce blocking. */
96
    rc = waitq_sleep_timeout_unsafe(wq, SYNCH_NO_TIMEOUT, SYNCH_FLAGS_NONE);
97
 
98
    waitq_sleep_finish(wq, rc, ipl);
99
}
100
 
3474 svoboda 101
/** Start of stoppable section.
102
 *
103
 * A stoppable section is a section of code where if the thread can be stoped. In other words,
104
 * if a STOP operation is issued, the thread is guaranteed not to execute
105
 * any userspace instructions until the thread is resumed.
106
 *
107
 * Having stoppable sections is better than having stopping points, since
108
 * a thread can be stopped even when it is blocked indefinitely in a system
109
 * call (whereas it would not reach any stopping point).
110
 */
3438 svoboda 111
void udebug_stoppable_begin(void)
112
{
113
    int nsc;
114
    call_t *db_call, *go_call;
115
 
116
    ASSERT(THREAD);
117
    ASSERT(TASK);
118
 
119
    mutex_lock(&TASK->udebug.lock);
120
 
121
    nsc = --TASK->udebug.not_stoppable_count;
122
 
123
    /* Lock order OK, THREAD->udebug.lock is after TASK->udebug.lock */
124
    mutex_lock(&THREAD->udebug.lock);
125
    ASSERT(THREAD->udebug.stoppable == false);
126
    THREAD->udebug.stoppable = true;
127
 
128
    if (TASK->udebug.dt_state == UDEBUG_TS_BEGINNING && nsc == 0) {
129
        /*
130
         * This was the last non-stoppable thread. Reply to
131
         * DEBUG_BEGIN call.
132
         */
133
 
134
        db_call = TASK->udebug.begin_call;
135
        ASSERT(db_call);
136
 
137
        TASK->udebug.dt_state = UDEBUG_TS_ACTIVE;
138
        TASK->udebug.begin_call = NULL;
139
 
140
        IPC_SET_RETVAL(db_call->data, 0);
141
        ipc_answer(&TASK->answerbox, db_call);     
142
 
143
    } else if (TASK->udebug.dt_state == UDEBUG_TS_ACTIVE) {
144
        /*
145
         * Active debugging session
146
         */
147
 
4337 svoboda 148
        if (THREAD->udebug.active == true &&
3674 svoboda 149
            THREAD->udebug.go == false) {
3438 svoboda 150
            /*
151
             * Thread was requested to stop - answer go call
152
             */
153
 
154
            /* Make sure nobody takes this call away from us */
155
            go_call = THREAD->udebug.go_call;
156
            THREAD->udebug.go_call = NULL;
157
            ASSERT(go_call);
158
 
159
            IPC_SET_RETVAL(go_call->data, 0);
160
            IPC_SET_ARG1(go_call->data, UDEBUG_EVENT_STOP);
161
 
162
            THREAD->udebug.cur_event = UDEBUG_EVENT_STOP;
163
 
164
                ipc_answer(&TASK->answerbox, go_call);
165
        }
166
    }
167
 
168
    mutex_unlock(&THREAD->udebug.lock);
169
        mutex_unlock(&TASK->udebug.lock);
170
}
171
 
3474 svoboda 172
/** End of a stoppable section.
173
 *
174
 * This is the point where the thread will block if it is stopped.
175
 * (As, by definition, a stopped thread must not leave its stoppable section).
176
 */
3438 svoboda 177
void udebug_stoppable_end(void)
178
{
179
restart:
180
    mutex_lock(&TASK->udebug.lock);
181
    mutex_lock(&THREAD->udebug.lock);
182
 
4337 svoboda 183
    if (THREAD->udebug.active && THREAD->udebug.go == false) {
3438 svoboda 184
        TASK->udebug.begin_call = NULL;
185
        mutex_unlock(&THREAD->udebug.lock);
186
        mutex_unlock(&TASK->udebug.lock);
187
 
188
        udebug_wait_for_go(&THREAD->udebug.go_wq);
189
 
190
        goto restart;
3674 svoboda 191
        /* Must try again - have to lose stoppability atomically. */
3438 svoboda 192
    } else {
193
        ++TASK->udebug.not_stoppable_count;
194
        ASSERT(THREAD->udebug.stoppable == true);
195
        THREAD->udebug.stoppable = false;
196
 
197
        mutex_unlock(&THREAD->udebug.lock);
198
        mutex_unlock(&TASK->udebug.lock);
199
    }
200
}
201
 
202
/** Upon being scheduled to run, check if the current thread should stop.
203
 *
3674 svoboda 204
 * This function is called from clock().
3438 svoboda 205
 */
206
void udebug_before_thread_runs(void)
207
{
208
    /* Check if we're supposed to stop */
209
    udebug_stoppable_begin();
210
    udebug_stoppable_end();
211
}
212
 
3474 svoboda 213
/** Syscall event hook.
214
 *
215
 * Must be called before and after servicing a system call. This generates
216
 * a SYSCALL_B or SYSCALL_E event, depending on the value of @a end_variant.
217
 */
3438 svoboda 218
void udebug_syscall_event(unative_t a1, unative_t a2, unative_t a3,
219
    unative_t a4, unative_t a5, unative_t a6, unative_t id, unative_t rc,
220
    bool end_variant)
221
{
222
    call_t *call;
223
    udebug_event_t etype;
224
 
225
    etype = end_variant ? UDEBUG_EVENT_SYSCALL_E : UDEBUG_EVENT_SYSCALL_B;
226
 
227
    mutex_lock(&TASK->udebug.lock);
228
    mutex_lock(&THREAD->udebug.lock);
229
 
3674 svoboda 230
    /* Must only generate events when in debugging session and is go. */
4337 svoboda 231
    if (THREAD->udebug.active != true || THREAD->udebug.go == false ||
3438 svoboda 232
        (TASK->udebug.evmask & UDEBUG_EVMASK(etype)) == 0) {
233
        mutex_unlock(&THREAD->udebug.lock);
234
        mutex_unlock(&TASK->udebug.lock);
235
        return;
236
    }
237
 
4389 svoboda 238
    /* Fill in the GO response. */
3438 svoboda 239
    call = THREAD->udebug.go_call;
240
    THREAD->udebug.go_call = NULL;
241
 
242
    IPC_SET_RETVAL(call->data, 0);
243
    IPC_SET_ARG1(call->data, etype);
244
    IPC_SET_ARG2(call->data, id);
245
    IPC_SET_ARG3(call->data, rc);
246
 
247
    THREAD->udebug.syscall_args[0] = a1;
248
    THREAD->udebug.syscall_args[1] = a2;
249
    THREAD->udebug.syscall_args[2] = a3;
250
    THREAD->udebug.syscall_args[3] = a4;
251
    THREAD->udebug.syscall_args[4] = a5;
252
    THREAD->udebug.syscall_args[5] = a6;
253
 
254
    /*
3674 svoboda 255
     * Make sure udebug.go is false when going to sleep
3438 svoboda 256
     * in case we get woken up by DEBUG_END. (At which
257
     * point it must be back to the initial true value).
258
     */
3674 svoboda 259
    THREAD->udebug.go = false;
3438 svoboda 260
    THREAD->udebug.cur_event = etype;
261
 
262
    ipc_answer(&TASK->answerbox, call);
263
 
264
    mutex_unlock(&THREAD->udebug.lock);
265
    mutex_unlock(&TASK->udebug.lock);
266
 
267
    udebug_wait_for_go(&THREAD->udebug.go_wq);
268
}
269
 
3674 svoboda 270
/** Thread-creation event hook combined with attaching the thread.
3474 svoboda 271
 *
272
 * Must be called when a new userspace thread is created in the debugged
3674 svoboda 273
 * task. Generates a THREAD_B event. Also attaches the thread @a t
274
 * to the task @a ta.
3474 svoboda 275
 *
3674 svoboda 276
 * This is necessary to avoid a race condition where the BEGIN and THREAD_READ
277
 * requests would be handled inbetween attaching the thread and checking it
278
 * for being in a debugging session to send the THREAD_B event. We could then
279
 * either miss threads or get some threads both in the thread list
280
 * and get a THREAD_B event for them.
281
 *
3474 svoboda 282
 * @param t Structure of the thread being created. Not locked, as the
283
 *      thread is not executing yet.
3674 svoboda 284
 * @param ta    Task to which the thread should be attached.
3474 svoboda 285
 */
3674 svoboda 286
void udebug_thread_b_event_attach(struct thread *t, struct task *ta)
3438 svoboda 287
{
288
    call_t *call;
289
 
290
    mutex_lock(&TASK->udebug.lock);
291
    mutex_lock(&THREAD->udebug.lock);
292
 
3674 svoboda 293
    thread_attach(t, ta);
294
 
4389 svoboda 295
    LOG("Check state");
3438 svoboda 296
 
297
    /* Must only generate events when in debugging session */
4337 svoboda 298
    if (THREAD->udebug.active != true) {
4389 svoboda 299
        LOG("udebug.active: %s, udebug.go: %s",
300
            THREAD->udebug.active ? "Yes(+)" : "No",
301
            THREAD->udebug.go ? "Yes(-)" : "No");
3438 svoboda 302
        mutex_unlock(&THREAD->udebug.lock);
303
        mutex_unlock(&TASK->udebug.lock);
304
        return;
305
    }
306
 
4389 svoboda 307
    LOG("Trigger event");
3438 svoboda 308
    call = THREAD->udebug.go_call;
309
    THREAD->udebug.go_call = NULL;
310
    IPC_SET_RETVAL(call->data, 0);
311
    IPC_SET_ARG1(call->data, UDEBUG_EVENT_THREAD_B);
312
    IPC_SET_ARG2(call->data, (unative_t)t);
313
 
314
    /*
3674 svoboda 315
     * Make sure udebug.go is false when going to sleep
3438 svoboda 316
     * in case we get woken up by DEBUG_END. (At which
317
     * point it must be back to the initial true value).
318
     */
3674 svoboda 319
    THREAD->udebug.go = false;
3438 svoboda 320
    THREAD->udebug.cur_event = UDEBUG_EVENT_THREAD_B;
321
 
322
    ipc_answer(&TASK->answerbox, call);
323
 
324
    mutex_unlock(&THREAD->udebug.lock);
325
    mutex_unlock(&TASK->udebug.lock);
326
 
4389 svoboda 327
    LOG("Wait for Go");
3438 svoboda 328
    udebug_wait_for_go(&THREAD->udebug.go_wq);
329
}
330
 
3474 svoboda 331
/** Thread-termination event hook.
332
 *
333
 * Must be called when the current thread is terminating.
334
 * Generates a THREAD_E event.
335
 */
3438 svoboda 336
void udebug_thread_e_event(void)
337
{
338
    call_t *call;
339
 
340
    mutex_lock(&TASK->udebug.lock);
341
    mutex_lock(&THREAD->udebug.lock);
342
 
4389 svoboda 343
    LOG("Check state");
3438 svoboda 344
 
3674 svoboda 345
    /* Must only generate events when in debugging session. */
4337 svoboda 346
    if (THREAD->udebug.active != true) {
4389 svoboda 347
        LOG("udebug.active: %s, udebug.go: %s",
348
            THREAD->udebug.active ? "Yes" : "No",
349
            THREAD->udebug.go ? "Yes" : "No");
3438 svoboda 350
        mutex_unlock(&THREAD->udebug.lock);
351
        mutex_unlock(&TASK->udebug.lock);
352
        return;
353
    }
354
 
4389 svoboda 355
    LOG("Trigger event");
3438 svoboda 356
    call = THREAD->udebug.go_call;
357
    THREAD->udebug.go_call = NULL;
358
    IPC_SET_RETVAL(call->data, 0);
359
    IPC_SET_ARG1(call->data, UDEBUG_EVENT_THREAD_E);
360
 
3674 svoboda 361
    /* Prevent any further debug activity in thread. */
4337 svoboda 362
    THREAD->udebug.active = false;
3438 svoboda 363
    THREAD->udebug.cur_event = 0;       /* none */
3674 svoboda 364
    THREAD->udebug.go = false;  /* set to initial value */
3438 svoboda 365
 
366
    ipc_answer(&TASK->answerbox, call);
367
 
368
    mutex_unlock(&THREAD->udebug.lock);
369
    mutex_unlock(&TASK->udebug.lock);
370
 
3674 svoboda 371
    /*
372
     * This event does not sleep - debugging has finished
373
     * in this thread.
374
     */
3438 svoboda 375
}
376
 
377
/**
378
 * Terminate task debugging session.
379
 *
3474 svoboda 380
 * Gracefully terminates the debugging session for a task. If the debugger
381
 * is still waiting for events on some threads, it will receive a
382
 * FINISHED event for each of them.
383
 *
384
 * @param ta    Task structure. ta->udebug.lock must be already locked.
385
 * @return  Zero on success or negative error code.
3438 svoboda 386
 */
387
int udebug_task_cleanup(struct task *ta)
388
{
389
    thread_t *t;
390
    link_t *cur;
391
    int flags;
392
    ipl_t ipl;
393
 
394
    if (ta->udebug.dt_state != UDEBUG_TS_BEGINNING &&
395
        ta->udebug.dt_state != UDEBUG_TS_ACTIVE) {
396
        return EINVAL;
397
    }
398
 
4389 svoboda 399
    LOG("Task %" PRIu64, ta->taskid);
400
 
3438 svoboda 401
    /* Finish debugging of all userspace threads */
402
    for (cur = ta->th_head.next; cur != &ta->th_head; cur = cur->next) {
403
        t = list_get_instance(cur, thread_t, th_link);
404
 
405
        mutex_lock(&t->udebug.lock);
406
 
407
        ipl = interrupts_disable();
408
        spinlock_lock(&t->lock);
409
 
410
        flags = t->flags;
411
 
412
        spinlock_unlock(&t->lock);
413
        interrupts_restore(ipl);
414
 
3674 svoboda 415
        /* Only process userspace threads. */
3438 svoboda 416
        if ((flags & THREAD_FLAG_USPACE) != 0) {
3674 svoboda 417
            /* Prevent any further debug activity in thread. */
4337 svoboda 418
            t->udebug.active = false;
3438 svoboda 419
            t->udebug.cur_event = 0;    /* none */
420
 
3674 svoboda 421
            /* Is the thread still go? */
422
            if (t->udebug.go == true) {
3438 svoboda 423
                /*
4337 svoboda 424
                * Yes, so clear go. As active == false,
3438 svoboda 425
                 * this doesn't affect anything.
426
                 */
3674 svoboda 427
                t->udebug.go = false;  
3438 svoboda 428
 
429
                /* Answer GO call */
4389 svoboda 430
                LOG("Answer GO call with EVENT_FINISHED.");
3438 svoboda 431
                IPC_SET_RETVAL(t->udebug.go_call->data, 0);
3474 svoboda 432
                IPC_SET_ARG1(t->udebug.go_call->data,
433
                    UDEBUG_EVENT_FINISHED);
3438 svoboda 434
 
435
                ipc_answer(&ta->answerbox, t->udebug.go_call);
436
                t->udebug.go_call = NULL;
437
            } else {
438
                /*
439
                 * Debug_stop is already at initial value.
440
                 * Yet this means the thread needs waking up.
441
                 */
442
 
443
                /*
444
                 * t's lock must not be held when calling
445
                 * waitq_wakeup.
446
                 */
447
                waitq_wakeup(&t->udebug.go_wq, WAKEUP_FIRST);
448
            }
449
        }
450
        mutex_unlock(&t->udebug.lock);
451
    }
452
 
453
    ta->udebug.dt_state = UDEBUG_TS_INACTIVE;
454
    ta->udebug.debugger = NULL;
455
 
456
    return 0;
457
}
458
 
459
 
460
/** @}
461
 */