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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 operations.
3474 svoboda 36
 *
37
 * Udebug operations on tasks and threads are implemented here. The
38
 * functions defined here are called from the udebug_ipc module
39
 * when servicing udebug IPC messages.
3438 svoboda 40
 */
41
 
3441 svoboda 42
#include <debug.h>
3438 svoboda 43
#include <proc/task.h>
44
#include <proc/thread.h>
45
#include <arch.h>
46
#include <errno.h>
47
#include <syscall/copy.h>
48
#include <ipc/ipc.h>
49
#include <udebug/udebug.h>
50
#include <udebug/udebug_ops.h>
51
 
52
/**
53
 * Prepare a thread for a debugging operation.
54
 *
55
 * Simply put, return thread t with t->udebug.lock held,
56
 * but only if it verifies all conditions.
57
 *
58
 * Specifically, verifies that thread t exists, is a userspace thread,
59
 * and belongs to the current task (TASK). Verifies, that the thread
3674 svoboda 60
 * is (or is not) go according to being_go (typically false).
4337 svoboda 61
 * It also locks t->udebug.lock, making sure that t->udebug.active
3438 svoboda 62
 * is true - that the thread is in a valid debugging session.
63
 *
64
 * With this verified and the t->udebug.lock mutex held, it is ensured
65
 * that the thread cannot leave the debugging session, let alone cease
66
 * to exist.
67
 *
68
 * In this function, holding the TASK->udebug.lock mutex prevents the
69
 * thread from leaving the debugging session, while relaxing from
70
 * the t->lock spinlock to the t->udebug.lock mutex.
71
 *
3474 svoboda 72
 * @param t     Pointer, need not at all be valid.
3674 svoboda 73
 * @param being_go  Required thread state.
3474 svoboda 74
 *
3438 svoboda 75
 * Returns EOK if all went well, or an error code otherwise.
76
 */
3674 svoboda 77
static int _thread_op_begin(thread_t *t, bool being_go)
3438 svoboda 78
{
79
    task_id_t taskid;
80
    ipl_t ipl;
81
 
82
    taskid = TASK->taskid;
83
 
84
    mutex_lock(&TASK->udebug.lock);
85
 
86
    /* thread_exists() must be called with threads_lock held */
87
    ipl = interrupts_disable();
88
    spinlock_lock(&threads_lock);
89
 
90
    if (!thread_exists(t)) {
91
        spinlock_unlock(&threads_lock);
92
        interrupts_restore(ipl);
93
        mutex_unlock(&TASK->udebug.lock);
94
        return ENOENT;
95
    }
96
 
97
    /* t->lock is enough to ensure the thread's existence */
98
    spinlock_lock(&t->lock);
99
    spinlock_unlock(&threads_lock);
100
 
3674 svoboda 101
    /* Verify that 't' is a userspace thread. */
3438 svoboda 102
    if ((t->flags & THREAD_FLAG_USPACE) == 0) {
103
        /* It's not, deny its existence */
104
        spinlock_unlock(&t->lock);
105
        interrupts_restore(ipl);
106
        mutex_unlock(&TASK->udebug.lock);
107
        return ENOENT;
108
    }
109
 
3674 svoboda 110
    /* Verify debugging state. */
4337 svoboda 111
    if (t->udebug.active != true) {
3438 svoboda 112
        /* Not in debugging session or undesired GO state */
113
        spinlock_unlock(&t->lock);
114
        interrupts_restore(ipl);
115
        mutex_unlock(&TASK->udebug.lock);
116
        return ENOENT;
117
    }
118
 
119
    /*
4337 svoboda 120
     * Since the thread has active == true, TASK->udebug.lock
121
     * is enough to ensure its existence and that active remains
3438 svoboda 122
     * true.
123
     */
124
    spinlock_unlock(&t->lock);
125
    interrupts_restore(ipl);
126
 
3674 svoboda 127
    /* Only mutex TASK->udebug.lock left. */
3438 svoboda 128
 
3674 svoboda 129
    /* Now verify that the thread belongs to the current task. */
3438 svoboda 130
    if (t->task != TASK) {
131
        /* No such thread belonging this task*/
132
        mutex_unlock(&TASK->udebug.lock);
133
        return ENOENT;
134
    }
135
 
136
    /*
137
     * Now we need to grab the thread's debug lock for synchronization
138
     * of the threads stoppability/stop state.
139
     */
140
    mutex_lock(&t->udebug.lock);
141
 
3674 svoboda 142
    /* The big task mutex is no longer needed. */
3438 svoboda 143
    mutex_unlock(&TASK->udebug.lock);
144
 
3674 svoboda 145
    if (t->udebug.go != being_go) {
146
        /* Not in debugging session or undesired GO state. */
3438 svoboda 147
        mutex_unlock(&t->udebug.lock);
148
        return EINVAL;
149
    }
150
 
3674 svoboda 151
    /* Only t->udebug.lock left. */
3438 svoboda 152
 
3674 svoboda 153
    return EOK; /* All went well. */
3438 svoboda 154
}
155
 
3474 svoboda 156
/** End debugging operation on a thread. */
3438 svoboda 157
static void _thread_op_end(thread_t *t)
158
{
159
    mutex_unlock(&t->udebug.lock);
160
}
161
 
3474 svoboda 162
/** Begin debugging the current task.
163
 *
164
 * Initiates a debugging session for the current task (and its threads).
165
 * When the debugging session has started a reply will be sent to the
166
 * UDEBUG_BEGIN call. This may happen immediately in this function if
167
 * all the threads in this task are stoppable at the moment and in this
168
 * case the function returns 1.
169
 *
170
 * Otherwise the function returns 0 and the reply will be sent as soon as
171
 * all the threads become stoppable (i.e. they can be considered stopped).
172
 *
173
 * @param call  The BEGIN call we are servicing.
174
 * @return  0 (OK, but not done yet), 1 (done) or negative error code.
3438 svoboda 175
 */
176
int udebug_begin(call_t *call)
177
{
178
    int reply;
179
 
180
    thread_t *t;
181
    link_t *cur;
182
 
3441 svoboda 183
    LOG("udebug_begin()\n");
3438 svoboda 184
 
185
    mutex_lock(&TASK->udebug.lock);
3441 svoboda 186
    LOG("debugging task %llu\n", TASK->taskid);
3438 svoboda 187
 
188
    if (TASK->udebug.dt_state != UDEBUG_TS_INACTIVE) {
189
        mutex_unlock(&TASK->udebug.lock);
3441 svoboda 190
        LOG("udebug_begin(): busy error\n");
3438 svoboda 191
 
192
        return EBUSY;
193
    }
194
 
195
    TASK->udebug.dt_state = UDEBUG_TS_BEGINNING;
196
    TASK->udebug.begin_call = call;
197
    TASK->udebug.debugger = call->sender;
198
 
199
    if (TASK->udebug.not_stoppable_count == 0) {
200
        TASK->udebug.dt_state = UDEBUG_TS_ACTIVE;
201
        TASK->udebug.begin_call = NULL;
202
        reply = 1; /* immediate reply */
203
    } else {
204
        reply = 0; /* no reply */
205
    }
206
 
4337 svoboda 207
    /* Set udebug.active on all of the task's userspace threads. */
3438 svoboda 208
 
209
    for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {
210
        t = list_get_instance(cur, thread_t, th_link);
211
 
212
        mutex_lock(&t->udebug.lock);
213
        if ((t->flags & THREAD_FLAG_USPACE) != 0)
4337 svoboda 214
            t->udebug.active = true;
3438 svoboda 215
        mutex_unlock(&t->udebug.lock);
216
    }
217
 
218
    mutex_unlock(&TASK->udebug.lock);
219
 
3441 svoboda 220
    LOG("udebug_begin() done (%s)\n",
3438 svoboda 221
        reply ? "reply" : "stoppability wait");
222
 
223
    return reply;
224
}
225
 
3474 svoboda 226
/** Finish debugging the current task.
227
 *
228
 * Closes the debugging session for the current task.
229
 * @return Zero on success or negative error code.
230
 */
3438 svoboda 231
int udebug_end(void)
232
{
233
    int rc;
234
 
3441 svoboda 235
    LOG("udebug_end()\n");
3438 svoboda 236
 
237
    mutex_lock(&TASK->udebug.lock);
3441 svoboda 238
    LOG("task %" PRIu64 "\n", TASK->taskid);
3438 svoboda 239
 
240
    rc = udebug_task_cleanup(TASK);
241
 
242
    mutex_unlock(&TASK->udebug.lock);
243
 
244
    return rc;
245
}
246
 
3474 svoboda 247
/** Set the event mask.
248
 *
249
 * Sets the event mask that determines which events are enabled.
250
 *
251
 * @param mask  Or combination of events that should be enabled.
252
 * @return  Zero on success or negative error code.
253
 */
3438 svoboda 254
int udebug_set_evmask(udebug_evmask_t mask)
255
{
3441 svoboda 256
    LOG("udebug_set_mask()\n");
3438 svoboda 257
 
258
    mutex_lock(&TASK->udebug.lock);
259
 
260
    if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
261
        mutex_unlock(&TASK->udebug.lock);
3441 svoboda 262
        LOG("udebug_set_mask(): not active debuging session\n");
3438 svoboda 263
 
264
        return EINVAL;
265
    }
266
 
267
    TASK->udebug.evmask = mask;
268
 
269
    mutex_unlock(&TASK->udebug.lock);
270
 
271
    return 0;
272
}
273
 
3474 svoboda 274
/** Give thread GO.
275
 *
3674 svoboda 276
 * Upon recieving a go message, the thread is given GO. Being GO
3474 svoboda 277
 * means the thread is allowed to execute userspace code (until
278
 * a debugging event or STOP occurs, at which point the thread loses GO.
279
 *
280
 * @param t The thread to operate on (unlocked and need not be valid).
281
 * @param call  The GO call that we are servicing.
282
 */
3438 svoboda 283
int udebug_go(thread_t *t, call_t *call)
284
{
285
    int rc;
286
 
3674 svoboda 287
    /* On success, this will lock t->udebug.lock. */
3438 svoboda 288
    rc = _thread_op_begin(t, false);
289
    if (rc != EOK) {
290
        return rc;
291
    }
292
 
293
    t->udebug.go_call = call;
3674 svoboda 294
    t->udebug.go = true;
3438 svoboda 295
    t->udebug.cur_event = 0;    /* none */
296
 
297
    /*
3674 svoboda 298
     * Neither t's lock nor threads_lock may be held during wakeup.
3438 svoboda 299
     */
300
    waitq_wakeup(&t->udebug.go_wq, WAKEUP_FIRST);
301
 
302
    _thread_op_end(t);
303
 
304
    return 0;
305
}
306
 
3474 svoboda 307
/** Stop a thread (i.e. take its GO away)
308
 *
309
 * Generates a STOP event as soon as the thread becomes stoppable (i.e.
310
 * can be considered stopped).
311
 *
312
 * @param t The thread to operate on (unlocked and need not be valid).
313
 * @param call  The GO call that we are servicing.
314
 */
3438 svoboda 315
int udebug_stop(thread_t *t, call_t *call)
316
{
317
    int rc;
318
 
3441 svoboda 319
    LOG("udebug_stop()\n");
3438 svoboda 320
 
321
    /*
322
     * On success, this will lock t->udebug.lock. Note that this makes sure
323
     * the thread is not stopped.
324
     */
325
    rc = _thread_op_begin(t, true);
326
    if (rc != EOK) {
327
        return rc;
328
    }
329
 
3674 svoboda 330
    /* Take GO away from the thread. */
331
    t->udebug.go = false;
3438 svoboda 332
 
3674 svoboda 333
    if (t->udebug.stoppable != true) {
334
        /* Answer will be sent when the thread becomes stoppable. */
3438 svoboda 335
        _thread_op_end(t);
336
        return 0;
337
    }
338
 
339
    /*
3674 svoboda 340
     * Answer GO call.
3438 svoboda 341
     */
3441 svoboda 342
    LOG("udebug_stop - answering go call\n");
3438 svoboda 343
 
3674 svoboda 344
    /* Make sure nobody takes this call away from us. */
3438 svoboda 345
    call = t->udebug.go_call;
346
    t->udebug.go_call = NULL;
347
 
348
    IPC_SET_RETVAL(call->data, 0);
349
    IPC_SET_ARG1(call->data, UDEBUG_EVENT_STOP);
3441 svoboda 350
    LOG("udebug_stop/ipc_answer\n");
3438 svoboda 351
 
352
    THREAD->udebug.cur_event = UDEBUG_EVENT_STOP;
353
 
354
    _thread_op_end(t);
355
 
3674 svoboda 356
    mutex_lock(&TASK->udebug.lock);
3438 svoboda 357
    ipc_answer(&TASK->answerbox, call);
358
    mutex_unlock(&TASK->udebug.lock);
359
 
3441 svoboda 360
    LOG("udebog_stop/done\n");
3438 svoboda 361
    return 0;
362
}
363
 
3474 svoboda 364
/** Read the list of userspace threads in the current task.
365
 *
366
 * The list takes the form of a sequence of thread hashes (i.e. the pointers
367
 * to thread structures). A buffer of size @a buf_size is allocated and
368
 * a pointer to it written to @a buffer. The sequence of hashes is written
369
 * into this buffer.
370
 *
371
 * If the sequence is longer than @a buf_size bytes, only as much hashes
372
 * as can fit are copied. The number of thread hashes copied is stored
373
 * in @a n.
374
 *
375
 * The rationale for having @a buf_size is that this function is only
376
 * used for servicing the THREAD_READ message, which always specifies
377
 * a maximum size for the userspace buffer.
378
 *
379
 * @param buffer    The buffer for storing thread hashes.
380
 * @param buf_size  Buffer size in bytes.
381
 * @param n     The actual number of hashes copied will be stored here.
382
 */
3438 svoboda 383
int udebug_thread_read(void **buffer, size_t buf_size, size_t *n)
384
{
385
    thread_t *t;
386
    link_t *cur;
387
    unative_t tid;
388
    unsigned copied_ids;
389
    ipl_t ipl;
390
    unative_t *id_buffer;
391
    int flags;
392
    size_t max_ids;
393
 
3441 svoboda 394
    LOG("udebug_thread_read()\n");
3438 svoboda 395
 
396
    /* Allocate a buffer to hold thread IDs */
397
    id_buffer = malloc(buf_size, 0);
398
 
399
    mutex_lock(&TASK->udebug.lock);
400
 
401
    /* Verify task state */
402
    if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
403
        mutex_unlock(&TASK->udebug.lock);
404
        return EINVAL;
405
    }
406
 
407
    ipl = interrupts_disable();
408
    spinlock_lock(&TASK->lock);
409
    /* Copy down the thread IDs */
410
 
411
    max_ids = buf_size / sizeof(unative_t);
412
    copied_ids = 0;
413
 
414
    /* FIXME: make sure the thread isn't past debug shutdown... */
415
    for (cur = TASK->th_head.next; cur != &TASK->th_head; cur = cur->next) {
416
        /* Do not write past end of buffer */
417
        if (copied_ids >= max_ids) break;
418
 
419
        t = list_get_instance(cur, thread_t, th_link);
420
 
421
        spinlock_lock(&t->lock);
422
        flags = t->flags;
423
        spinlock_unlock(&t->lock);
424
 
3674 svoboda 425
        /* Not interested in kernel threads. */
3438 svoboda 426
        if ((flags & THREAD_FLAG_USPACE) != 0) {
427
            /* Using thread struct pointer as identification hash */
428
            tid = (unative_t) t;
429
            id_buffer[copied_ids++] = tid;
430
        }
431
    }
432
 
433
    spinlock_unlock(&TASK->lock);
434
    interrupts_restore(ipl);
435
 
436
    mutex_unlock(&TASK->udebug.lock);
437
 
438
    *buffer = id_buffer;
439
    *n = copied_ids * sizeof(unative_t);
440
 
441
    return 0;
442
}
443
 
3474 svoboda 444
/** Read the arguments of a system call.
445
 *
446
 * The arguments of the system call being being executed are copied
447
 * to an allocated buffer and a pointer to it is written to @a buffer.
448
 * The size of the buffer is exactly such that it can hold the maximum number
449
 * of system-call arguments.
450
 *
451
 * Unless the thread is currently blocked in a SYSCALL_B or SYSCALL_E event,
452
 * this function will fail with an EINVAL error code.
453
 *
454
 * @param buffer    The buffer for storing thread hashes.
455
 */
3438 svoboda 456
int udebug_args_read(thread_t *t, void **buffer)
457
{
458
    int rc;
459
    unative_t *arg_buffer;
460
 
3674 svoboda 461
    /* Prepare a buffer to hold the arguments. */
3438 svoboda 462
    arg_buffer = malloc(6 * sizeof(unative_t), 0);
463
 
3674 svoboda 464
    /* On success, this will lock t->udebug.lock. */
3438 svoboda 465
    rc = _thread_op_begin(t, false);
466
    if (rc != EOK) {
467
        return rc;
468
    }
469
 
3674 svoboda 470
    /* Additionally we need to verify that we are inside a syscall. */
3438 svoboda 471
    if (t->udebug.cur_event != UDEBUG_EVENT_SYSCALL_B &&
472
        t->udebug.cur_event != UDEBUG_EVENT_SYSCALL_E) {
473
        _thread_op_end(t);
474
        return EINVAL;
475
    }
476
 
3674 svoboda 477
    /* Copy to a local buffer before releasing the lock. */
3438 svoboda 478
    memcpy(arg_buffer, t->udebug.syscall_args, 6 * sizeof(unative_t));
479
 
480
    _thread_op_end(t);
481
 
482
    *buffer = arg_buffer;
483
    return 0;
484
}
485
 
3474 svoboda 486
/** Read the memory of the debugged task.
487
 *
488
 * Reads @a n bytes from the address space of the debugged task, starting
489
 * from @a uspace_addr. The bytes are copied into an allocated buffer
490
 * and a pointer to it is written into @a buffer.
491
 *
492
 * @param uspace_addr   Address from where to start reading.
493
 * @param n     Number of bytes to read.
494
 * @param buffer    For storing a pointer to the allocated buffer.
495
 */
3438 svoboda 496
int udebug_mem_read(unative_t uspace_addr, size_t n, void **buffer)
497
{
498
    void *data_buffer;
499
    int rc;
500
 
501
    /* Verify task state */
502
    mutex_lock(&TASK->udebug.lock);
503
 
504
    if (TASK->udebug.dt_state != UDEBUG_TS_ACTIVE) {
505
        mutex_unlock(&TASK->udebug.lock);
506
        return EBUSY;
507
    }
508
 
509
    data_buffer = malloc(n, 0);
510
 
511
    /* NOTE: this is not strictly from a syscall... but that shouldn't
512
     * be a problem */
513
    rc = copy_from_uspace(data_buffer, (void *)uspace_addr, n);
514
    mutex_unlock(&TASK->udebug.lock);
515
 
516
    if (rc != 0) return rc;
517
 
518
    *buffer = data_buffer;
519
    return 0;
520
}
521
 
522
/** @}
523
 */