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fb0e1ba7 MK |
1 | /* Multi-threaded debugging support for Linux (LWP layer). |
2 | Copyright 2000 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GDB. | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program; if not, write to the Free Software | |
18 | Foundation, Inc., 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | #include "defs.h" | |
22 | ||
23 | #include "gdb_assert.h" | |
24 | #include <errno.h> | |
25 | #include <signal.h> | |
26 | #include <sys/ptrace.h> | |
27 | #include "gdb_wait.h" | |
28 | ||
29 | #include "gdbthread.h" | |
30 | #include "inferior.h" | |
31 | #include "target.h" | |
32 | ||
33 | #define DEBUG 1 | |
34 | ||
35 | #if DEBUG | |
36 | extern const char *strsignal (int sig); | |
37 | #endif | |
38 | ||
39 | /* On Linux there are no real LWP's. The closest thing to LWP's are | |
40 | processes sharing the same VM space. A multi-threaded process is | |
41 | basically a group of such processes. However, such a grouping is | |
42 | almost entirely a user-space issue; the kernel doesn't enforce such | |
43 | a grouping at all (this might change in the future). In general, | |
44 | we'll rely on the threads library (i.e. the LinuxThreads library) | |
45 | to provide such a grouping. | |
46 | ||
47 | It is perfectly well possible to write a multi-threaded application | |
48 | without the assistance of a threads library, by using the clone | |
49 | system call directly. This module should be able to give some | |
50 | rudimentary support for debugging such applications if developers | |
51 | specify the CLONE_PTRACE flag in the clone system call, and are | |
52 | using Linux 2.4 or above. | |
53 | ||
54 | Note that there are some peculiarities in Linux that affect this | |
55 | code: | |
56 | ||
57 | - In general one should specify the __WCLONE flag to waitpid in | |
58 | order to make it report events for any of the cloned processes. | |
59 | However, if a cloned process has exited the exit status is only | |
60 | reported if the __WCLONE flag is absent. | |
61 | ||
62 | - When a traced, cloned process exits and is waited for by the | |
63 | debugger, the kernel reassigns it to the origional parent and | |
64 | keeps it around as a "zombie". Somehow, the LinuxThreads library | |
65 | doesn't notice this, which leads to the "zombie problem": When | |
66 | debugged a multi-threaded process that spawns a lot of threads | |
67 | will run out of processes, even if the threads exit, because the | |
68 | "zombies" stay around. */ | |
69 | ||
70 | /* Structure describing a LWP. */ | |
71 | struct lwp_info | |
72 | { | |
73 | /* The process id of the LWP. This is a combination of the LWP id | |
74 | and overall process id. */ | |
75 | int pid; | |
76 | ||
77 | /* Non-zero if we sent this LWP a SIGSTOP (but the LWP didn't report | |
78 | it back yet). */ | |
79 | int signalled; | |
80 | ||
81 | /* Non-zero if this LWP is stopped. */ | |
82 | int stopped; | |
83 | ||
84 | /* If non-zero, a pending wait status. */ | |
85 | int status; | |
86 | ||
87 | /* Non-zero if we were stepping this LWP. */ | |
88 | int step; | |
89 | ||
90 | /* Next LWP in list. */ | |
91 | struct lwp_info *next; | |
92 | }; | |
93 | ||
94 | /* List of known LWPs. */ | |
95 | static struct lwp_info *lwp_list; | |
96 | ||
97 | /* Number of LWPs in the list. */ | |
98 | static int num_lwps; | |
99 | ||
100 | /* Non-zero if we're running in "threaded" mode. */ | |
101 | static int threaded; | |
102 | \f | |
103 | ||
104 | #ifndef TIDGET | |
105 | #define TIDGET(PID) (((PID) & 0x7fffffff) >> 16) | |
106 | #define PIDGET(PID) (((PID) & 0xffff)) | |
107 | #define MERGEPID(PID, TID) (((PID) & 0xffff) | ((TID) << 16)) | |
108 | #endif | |
109 | ||
110 | #define THREAD_FLAG 0x80000000 | |
111 | #define is_lwp(pid) (((pid) & THREAD_FLAG) == 0 && TIDGET (pid)) | |
112 | #define GET_LWP(pid) TIDGET (pid) | |
113 | #define GET_PID(pid) PIDGET (pid) | |
114 | #define BUILD_LWP(tid, pid) MERGEPID (pid, tid) | |
115 | ||
116 | #define is_cloned(pid) (GET_LWP (pid) != GET_PID (pid)) | |
117 | ||
118 | /* If the last reported event was a SIGTRAP, this variable is set to | |
119 | the process id of the LWP/thread that got it. */ | |
120 | int trap_pid; | |
121 | \f | |
122 | ||
123 | /* This module's target-specific operations. */ | |
124 | static struct target_ops lin_lwp_ops; | |
125 | ||
126 | /* The standard child operations. */ | |
127 | extern struct target_ops child_ops; | |
128 | ||
129 | /* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in | |
130 | _initialize_lin_lwp. */ | |
131 | static sigset_t suspend_mask; | |
132 | \f | |
133 | ||
134 | /* Prototypes for local functions. */ | |
135 | static void lin_lwp_mourn_inferior (void); | |
136 | \f | |
137 | ||
138 | /* Initialize the list of LWPs. */ | |
139 | ||
140 | static void | |
141 | init_lwp_list (void) | |
142 | { | |
143 | struct lwp_info *lp, *lpnext; | |
144 | ||
145 | for (lp = lwp_list; lp; lp = lpnext) | |
146 | { | |
147 | lpnext = lp->next; | |
148 | free (lp); | |
149 | } | |
150 | ||
151 | lwp_list = NULL; | |
152 | num_lwps = 0; | |
153 | threaded = 0; | |
154 | } | |
155 | ||
156 | /* Add the LWP specified by PID to the list. If this causes the | |
157 | number of LWPs to become larger than one, go into "threaded" mode. | |
158 | Return a pointer to the structure describing the new LWP. */ | |
159 | ||
160 | static struct lwp_info * | |
161 | add_lwp (int pid) | |
162 | { | |
163 | struct lwp_info *lp; | |
164 | ||
165 | gdb_assert (is_lwp (pid)); | |
166 | ||
167 | lp = (struct lwp_info *) xmalloc (sizeof (struct lwp_info)); | |
168 | ||
169 | memset (lp, 0, sizeof (struct lwp_info)); | |
170 | ||
171 | lp->pid = pid; | |
172 | ||
173 | lp->next = lwp_list; | |
174 | lwp_list = lp; | |
175 | if (++num_lwps > 1) | |
176 | threaded = 1; | |
177 | ||
178 | return lp; | |
179 | } | |
180 | ||
181 | /* Remove the LWP specified by PID from the list. */ | |
182 | ||
183 | static void | |
184 | delete_lwp (int pid) | |
185 | { | |
186 | struct lwp_info *lp, *lpprev; | |
187 | ||
188 | lpprev = NULL; | |
189 | ||
190 | for (lp = lwp_list; lp; lpprev = lp, lp = lp->next) | |
191 | if (lp->pid == pid) | |
192 | break; | |
193 | ||
194 | if (!lp) | |
195 | return; | |
196 | ||
197 | /* We don't go back to "non-threaded" mode if the number of threads | |
198 | becomes less than two. */ | |
199 | num_lwps--; | |
200 | ||
201 | if (lpprev) | |
202 | lpprev->next = lp->next; | |
203 | else | |
204 | lwp_list = lp->next; | |
205 | ||
206 | free (lp); | |
207 | } | |
208 | ||
209 | /* Return a pointer to the structure describing the LWP corresponding | |
210 | to PID. If no corresponding LWP could be found, return NULL. */ | |
211 | ||
212 | static struct lwp_info * | |
213 | find_lwp_pid (int pid) | |
214 | { | |
215 | struct lwp_info *lp; | |
216 | ||
217 | if (is_lwp (pid)) | |
218 | pid = GET_LWP (pid); | |
219 | ||
220 | for (lp = lwp_list; lp; lp = lp->next) | |
221 | if (pid == GET_LWP (lp->pid)) | |
222 | return lp; | |
223 | ||
224 | return NULL; | |
225 | } | |
226 | ||
227 | /* Call CALLBACK with its second argument set to DATA for every LWP in | |
228 | the list. If CALLBACK returns 1 for a particular LWP, return a | |
229 | pointer to the structure describing that LWP immediately. | |
230 | Otherwise return NULL. */ | |
231 | ||
232 | struct lwp_info * | |
233 | iterate_over_lwps (int (*callback) (struct lwp_info *, void *), void *data) | |
234 | { | |
235 | struct lwp_info *lp; | |
236 | ||
237 | for (lp = lwp_list; lp; lp = lp->next) | |
238 | if ((*callback) (lp, data)) | |
239 | return lp; | |
240 | ||
241 | return NULL; | |
242 | } | |
243 | \f | |
244 | ||
245 | /* Helper functions. */ | |
246 | ||
247 | static void | |
248 | restore_inferior_pid (void *arg) | |
249 | { | |
250 | int *saved_pid_ptr = arg; | |
251 | inferior_pid = *saved_pid_ptr; | |
252 | free (arg); | |
253 | } | |
254 | ||
255 | static struct cleanup * | |
256 | save_inferior_pid (void) | |
257 | { | |
258 | int *saved_pid_ptr; | |
259 | ||
260 | saved_pid_ptr = xmalloc (sizeof (int)); | |
261 | *saved_pid_ptr = inferior_pid; | |
262 | return make_cleanup (restore_inferior_pid, saved_pid_ptr); | |
263 | } | |
264 | \f | |
265 | ||
266 | /* Implementation of the PREPARE_TO_PROCEED hook for the Linux LWP layer. */ | |
267 | ||
268 | int | |
269 | lin_lwp_prepare_to_proceed (void) | |
270 | { | |
271 | if (trap_pid && inferior_pid != trap_pid) | |
272 | { | |
273 | /* Switched over from TRAP_PID. */ | |
274 | CORE_ADDR stop_pc = read_pc (); | |
275 | CORE_ADDR trap_pc; | |
276 | ||
277 | /* Avoid switching where it wouldn't do any good, i.e. if both | |
278 | threads are at the same breakpoint. */ | |
279 | trap_pc = read_pc_pid (trap_pid); | |
280 | if (trap_pc != stop_pc && breakpoint_here_p (trap_pc)) | |
281 | { | |
282 | /* User hasn't deleted the breakpoint. Return non-zero, and | |
283 | switch back to TRAP_PID. */ | |
284 | inferior_pid = trap_pid; | |
285 | ||
286 | /* FIXME: Is this stuff really necessary? */ | |
287 | flush_cached_frames (); | |
288 | registers_changed (); | |
289 | ||
290 | return 1; | |
291 | } | |
292 | } | |
293 | ||
294 | return 0; | |
295 | } | |
296 | \f | |
297 | ||
298 | #if 0 | |
299 | static void | |
300 | lin_lwp_open (char *args, int from_tty) | |
301 | { | |
302 | push_target (&lin_lwp_ops); | |
303 | } | |
304 | #endif | |
305 | ||
306 | /* Attach to the LWP specified by PID. If VERBOSE is non-zero, print | |
307 | a message telling the user that a new LWP has been added to the | |
308 | process. */ | |
309 | ||
310 | void | |
311 | lin_lwp_attach_lwp (int pid, int verbose) | |
312 | { | |
313 | struct lwp_info *lp; | |
314 | ||
315 | gdb_assert (is_lwp (pid)); | |
316 | ||
317 | if (verbose) | |
318 | printf_filtered ("[New %s]\n", target_pid_to_str (pid)); | |
319 | ||
320 | if (ptrace (PTRACE_ATTACH, GET_LWP (pid), 0, 0) < 0) | |
321 | error ("Can't attach %s: %s", target_pid_to_str (pid), strerror (errno)); | |
322 | ||
323 | lp = add_lwp (pid); | |
324 | lp->signalled = 1; | |
325 | } | |
326 | ||
327 | static void | |
328 | lin_lwp_attach (char *args, int from_tty) | |
329 | { | |
330 | /* FIXME: We should probably accept a list of process id's, and | |
331 | attach all of them. */ | |
332 | error("Not implemented yet"); | |
333 | } | |
334 | ||
335 | static void | |
336 | lin_lwp_detach (char *args, int from_tty) | |
337 | { | |
338 | /* FIXME: Provide implementation when we implement lin_lwp_attach. */ | |
339 | error ("Not implemented yet"); | |
340 | } | |
341 | \f | |
342 | ||
343 | struct private_thread_info | |
344 | { | |
345 | int lwpid; | |
346 | }; | |
347 | ||
348 | /* Return non-zero if TP corresponds to the LWP specified by DATA | |
349 | (which is assumed to be a pointer to a `struct lwp_info'. */ | |
350 | ||
351 | static int | |
352 | find_lwp_callback (struct thread_info *tp, void *data) | |
353 | { | |
354 | struct lwp_info *lp = data; | |
355 | ||
356 | if (tp->private->lwpid == GET_LWP (lp->pid)) | |
357 | return 1; | |
358 | ||
359 | return 0; | |
360 | } | |
361 | ||
362 | /* Resume LP. */ | |
363 | ||
364 | static int | |
365 | resume_callback (struct lwp_info *lp, void *data) | |
366 | { | |
367 | if (lp->stopped && lp->status == 0) | |
368 | { | |
369 | struct thread_info *tp; | |
370 | ||
371 | #if 1 | |
372 | /* FIXME: kettenis/2000-08-26: This should really be handled | |
373 | properly by core GDB. */ | |
374 | ||
375 | tp = find_thread_pid (lp->pid); | |
376 | if (tp == NULL) | |
377 | tp = iterate_over_threads (find_lwp_callback, lp); | |
378 | gdb_assert (tp); | |
379 | ||
380 | /* If we were previously stepping the thread, and now continue | |
381 | the thread we must invalidate the stepping range. However, | |
382 | if there is a step_resume breakpoint for this thread, we must | |
383 | preserve the stepping range to make it possible to continue | |
384 | stepping once we hit it. */ | |
385 | if (tp->step_range_end && tp->step_resume_breakpoint == NULL) | |
386 | { | |
387 | gdb_assert (lp->step); | |
388 | tp->step_range_start = tp->step_range_end = 0; | |
389 | } | |
390 | #endif | |
391 | ||
392 | child_resume (GET_LWP (lp->pid), 0, TARGET_SIGNAL_0); | |
393 | lp->stopped = 0; | |
394 | lp->step = 0; | |
395 | } | |
396 | ||
397 | return 0; | |
398 | } | |
399 | ||
400 | static void | |
401 | lin_lwp_resume (int pid, int step, enum target_signal signo) | |
402 | { | |
403 | struct lwp_info *lp; | |
404 | int resume_all; | |
405 | ||
406 | /* Apparently the interpretation of PID is dependent on STEP: If | |
407 | STEP is non-zero, a specific PID means `step only this process | |
408 | id'. But if STEP is zero, then PID means `continue *all* | |
409 | processes, but give the signal only to this one'. */ | |
410 | resume_all = (pid == -1) || !step; | |
411 | ||
412 | /* If PID is -1, it's the current inferior that should be | |
413 | handled special. */ | |
414 | if (pid == -1) | |
415 | pid = inferior_pid; | |
416 | ||
417 | lp = find_lwp_pid (pid); | |
418 | if (lp) | |
419 | { | |
420 | pid = GET_LWP (lp->pid); | |
421 | ||
422 | /* Mark LWP as not stopped to prevent it from being continued by | |
423 | resume_callback. */ | |
424 | lp->stopped = 0; | |
425 | ||
426 | /* Remember if we're stepping. */ | |
427 | lp->step = step; | |
428 | ||
429 | /* If we have a pending wait status for this thread, there is no | |
430 | point in resuming the process. */ | |
431 | if (lp->status) | |
432 | { | |
433 | /* FIXME: What should we do if we are supposed to continue | |
434 | this thread with a signal? */ | |
435 | gdb_assert (signo == TARGET_SIGNAL_0); | |
436 | return; | |
437 | } | |
438 | } | |
439 | ||
440 | if (resume_all) | |
441 | iterate_over_lwps (resume_callback, NULL); | |
442 | ||
443 | child_resume (pid, step, signo); | |
444 | } | |
445 | \f | |
446 | ||
447 | /* Send a SIGSTOP to LP. */ | |
448 | ||
449 | static int | |
450 | stop_callback (struct lwp_info *lp, void *data) | |
451 | { | |
452 | if (! lp->stopped && ! lp->signalled) | |
453 | { | |
454 | int ret; | |
455 | ||
456 | ret = kill (GET_LWP (lp->pid), SIGSTOP); | |
457 | gdb_assert (ret == 0); | |
458 | ||
459 | lp->signalled = 1; | |
460 | gdb_assert (lp->status == 0); | |
461 | } | |
462 | ||
463 | return 0; | |
464 | } | |
465 | ||
466 | /* Wait until LP is stopped. */ | |
467 | ||
468 | static int | |
469 | stop_wait_callback (struct lwp_info *lp, void *data) | |
470 | { | |
471 | if (! lp->stopped && lp->signalled) | |
472 | { | |
473 | pid_t pid; | |
474 | int status; | |
475 | ||
476 | gdb_assert (lp->status == 0); | |
477 | ||
478 | pid = waitpid (GET_LWP (lp->pid), &status, | |
479 | is_cloned (lp->pid) ? __WCLONE : 0); | |
480 | if (pid == -1 && errno == ECHILD) | |
481 | /* OK, the proccess has disappeared. We'll catch the actual | |
482 | exit event in lin_lwp_wait. */ | |
483 | return 0; | |
484 | ||
485 | gdb_assert (pid == GET_LWP (lp->pid)); | |
486 | ||
487 | if (WIFEXITED (status) || WIFSIGNALED (status)) | |
488 | { | |
489 | gdb_assert (num_lwps > 1); | |
490 | gdb_assert (! is_cloned (lp->pid)); | |
491 | ||
492 | gdb_assert (in_thread_list (lp->pid)); | |
493 | if (lp->pid != inferior_pid) | |
494 | delete_thread (lp->pid); | |
495 | printf_unfiltered ("[%s exited]\n", | |
496 | target_pid_to_str (lp->pid)); | |
497 | ||
498 | delete_lwp (lp->pid); | |
499 | return 0; | |
500 | } | |
501 | ||
502 | gdb_assert (WIFSTOPPED (status)); | |
503 | lp->stopped = 1; | |
504 | ||
505 | if (WSTOPSIG (status) != SIGSTOP) | |
506 | { | |
507 | if (WSTOPSIG (status) == SIGTRAP | |
508 | && breakpoint_inserted_here_p (read_pc_pid (pid) | |
509 | - DECR_PC_AFTER_BREAK)) | |
510 | { | |
511 | /* If a LWP other than the LWP that we're reporting an | |
512 | event for has hit a GDB breakpoint (as opposed to | |
513 | some random trap signal), then just arrange for it to | |
514 | hit it again later. We don't keep the SIGTRAP status | |
515 | and don't forward the SIGTRAP signal to the LWP. We | |
516 | will handle the current event, eventually we will | |
517 | resume all LWPs, and this one will get its breakpoint | |
518 | trap again. | |
519 | ||
520 | If we do not do this, then we run the risk that the | |
521 | user will delete or disable the breakpoint, but the | |
522 | thread will have already tripped on it. */ | |
523 | #if DEBUG | |
524 | printf ("Tripped breakpoint at %lx in LWP %d" | |
525 | " while waiting for SIGSTOP.\n", | |
526 | (long) read_pc_pid (lp->pid), pid); | |
527 | #endif | |
528 | /* Set the PC to before the trap. */ | |
529 | if (DECR_PC_AFTER_BREAK) | |
530 | write_pc_pid (read_pc_pid (pid) - DECR_PC_AFTER_BREAK, pid); | |
531 | } | |
532 | else | |
533 | { | |
534 | #if DEBUG | |
535 | printf ("Received %s in LWP %d while waiting for SIGSTOP.\n", | |
536 | strsignal (WSTOPSIG (status)), pid); | |
537 | #endif | |
538 | /* The thread was stopped with a signal other than | |
539 | SIGSTOP, and didn't accidentiliy trip a breakpoint. | |
540 | Record the wait status. */ | |
541 | lp->status = status; | |
542 | } | |
543 | } | |
544 | else | |
545 | { | |
546 | /* We caught the SIGSTOP that we intended to catch, so | |
547 | there's no SIGSTOP pending. */ | |
548 | lp->signalled = 0; | |
549 | } | |
550 | } | |
551 | ||
552 | return 0; | |
553 | } | |
554 | ||
555 | /* Return non-zero if LP has a wait status pending. */ | |
556 | ||
557 | static int | |
558 | status_callback (struct lwp_info *lp, void *data) | |
559 | { | |
560 | return (lp->status != 0); | |
561 | } | |
562 | ||
563 | /* Return non-zero if LP isn't stopped. */ | |
564 | ||
565 | static int | |
566 | running_callback (struct lwp_info *lp, void *data) | |
567 | { | |
568 | return (lp->stopped == 0); | |
569 | } | |
570 | ||
571 | static int | |
572 | lin_lwp_wait (int pid, struct target_waitstatus *ourstatus) | |
573 | { | |
574 | struct lwp_info *lp = NULL; | |
575 | int options = 0; | |
576 | int status = 0; | |
577 | ||
578 | retry: | |
579 | ||
580 | /* First check if there is a LWP with a wait status pending. */ | |
581 | if (pid == -1) | |
582 | { | |
583 | /* Any LWP will do. */ | |
584 | lp = iterate_over_lwps (status_callback, NULL); | |
585 | if (lp) | |
586 | { | |
587 | #if DEBUG | |
588 | printf ("Using pending wait status for LWP %d.\n", | |
589 | GET_LWP (lp->pid)); | |
590 | #endif | |
591 | status = lp->status; | |
592 | lp->status = 0; | |
593 | } | |
594 | ||
595 | /* But if we don't fine one, we'll have to wait, and check both | |
596 | cloned and uncloned processes. We start with the cloned | |
597 | processes. */ | |
598 | options = __WCLONE | WNOHANG; | |
599 | } | |
600 | else if (is_lwp (pid)) | |
601 | { | |
602 | #if DEBUG | |
603 | printf ("Waiting for specific LWP %d.\n", GET_LWP (pid)); | |
604 | #endif | |
605 | /* We have a specific LWP to check. */ | |
606 | lp = find_lwp_pid (GET_LWP (pid)); | |
607 | gdb_assert (lp); | |
608 | status = lp->status; | |
609 | lp->status = 0; | |
610 | #if DEBUG | |
611 | if (status) | |
612 | printf ("Using pending wait status for LWP %d.\n", | |
613 | GET_LWP (lp->pid)); | |
614 | #endif | |
615 | ||
616 | /* If we have to wait, take into account whether PID is a cloned | |
617 | process or not. And we have to convert it to something that | |
618 | the layer beneath us can understand. */ | |
619 | options = is_cloned (lp->pid) ? __WCLONE : 0; | |
620 | pid = GET_LWP (pid); | |
621 | } | |
622 | ||
623 | if (status && lp->signalled) | |
624 | { | |
625 | /* A pending SIGSTOP may interfere with the normal stream of | |
626 | events. In a typical case where interference is a problem, | |
627 | we have a SIGSTOP signal pending for LWP A while | |
628 | single-stepping it, encounter an event in LWP B, and take the | |
629 | pending SIGSTOP while trying to stop LWP A. After processing | |
630 | the event in LWP B, LWP A is continued, and we'll never see | |
631 | the SIGTRAP associated with the last time we were | |
632 | single-stepping LWP A. */ | |
633 | ||
634 | /* Resume the thread. It should halt immediately returning the | |
635 | pending SIGSTOP. */ | |
636 | child_resume (GET_LWP (lp->pid), lp->step, TARGET_SIGNAL_0); | |
637 | lp->stopped = 0; | |
638 | ||
639 | /* This should catch the pending SIGSTOP. */ | |
640 | stop_wait_callback (lp, NULL); | |
641 | } | |
642 | ||
643 | set_sigint_trap (); /* Causes SIGINT to be passed on to the | |
644 | attached process. */ | |
645 | set_sigio_trap (); | |
646 | ||
647 | while (status == 0) | |
648 | { | |
649 | pid_t lwpid; | |
650 | ||
651 | lwpid = waitpid (pid, &status, options); | |
652 | if (lwpid > 0) | |
653 | { | |
654 | gdb_assert (pid == -1 || lwpid == pid); | |
655 | ||
656 | lp = find_lwp_pid (lwpid); | |
657 | if (! lp) | |
658 | { | |
659 | lp = add_lwp (BUILD_LWP (lwpid, inferior_pid)); | |
660 | if (threaded) | |
661 | { | |
662 | gdb_assert (WIFSTOPPED (status) && WSTOPSIG (status) == SIGSTOP); | |
663 | lp->signalled = 1; | |
664 | ||
665 | if (! in_thread_list (inferior_pid)) | |
666 | { | |
667 | inferior_pid = BUILD_LWP (inferior_pid, inferior_pid); | |
668 | add_thread (inferior_pid); | |
669 | } | |
670 | ||
671 | add_thread (lp->pid); | |
672 | printf_unfiltered ("[New %s]\n", | |
673 | target_pid_to_str (lp->pid)); | |
674 | } | |
675 | } | |
676 | ||
677 | /* Make sure we don't report a TARGET_WAITKIND_EXITED or | |
678 | TARGET_WAITKIND_SIGNALLED event if there are still LWP's | |
679 | left in the process. */ | |
680 | if ((WIFEXITED (status) || WIFSIGNALED (status)) && num_lwps > 1) | |
681 | { | |
682 | if (in_thread_list (lp->pid)) | |
683 | { | |
684 | /* Core GDB cannot deal with us deeting the current | |
685 | thread. */ | |
686 | if (lp->pid != inferior_pid) | |
687 | delete_thread (lp->pid); | |
688 | printf_unfiltered ("[%s exited]\n", | |
689 | target_pid_to_str (lp->pid)); | |
690 | } | |
691 | #if DEBUG | |
692 | printf ("%s exited.\n", target_pid_to_str (lp->pid)); | |
693 | #endif | |
694 | delete_lwp (lp->pid); | |
695 | ||
696 | /* Make sure there is at least one thread running. */ | |
697 | gdb_assert (iterate_over_lwps (running_callback, NULL)); | |
698 | ||
699 | /* Discard the event. */ | |
700 | status = 0; | |
701 | continue; | |
702 | } | |
703 | ||
704 | /* Make sure we don't report a SIGSTOP that we sent | |
705 | ourselves in an attempt to stop an LWP. */ | |
706 | if (lp->signalled && WIFSTOPPED (status) | |
707 | && WSTOPSIG (status) == SIGSTOP) | |
708 | { | |
709 | #if DEBUG | |
710 | printf ("Delayed SIGSTOP caught for %s.\n", | |
711 | target_pid_to_str (lp->pid)); | |
712 | #endif | |
713 | /* This is a delayed SIGSTOP. */ | |
714 | lp->signalled = 0; | |
715 | ||
716 | child_resume (GET_LWP (lp->pid), lp->step, TARGET_SIGNAL_0); | |
717 | lp->stopped = 0; | |
718 | ||
719 | /* Discard the event. */ | |
720 | status = 0; | |
721 | continue; | |
722 | } | |
723 | ||
724 | break; | |
725 | } | |
726 | ||
727 | if (pid == -1) | |
728 | { | |
729 | /* Alternate between checking cloned and uncloned processes. */ | |
730 | options ^= __WCLONE; | |
731 | ||
732 | /* And suspend every time we have checked both. */ | |
733 | if (options & __WCLONE) | |
734 | sigsuspend (&suspend_mask); | |
735 | } | |
736 | ||
737 | /* We shouldn't end up here unless we want to try again. */ | |
738 | gdb_assert (status == 0); | |
739 | } | |
740 | ||
741 | clear_sigio_trap (); | |
742 | clear_sigint_trap (); | |
743 | ||
744 | gdb_assert (lp); | |
745 | ||
746 | /* Don't report signals that GDB isn't interested in, such as | |
747 | signals that are neither printed nor stopped upon. Stopping all | |
748 | threads can be a bit time-consuming so if we want decent | |
749 | performance with heavily multi-threaded programs, especially when | |
750 | they're using a high frequency timer, we'd better avoid it if we | |
751 | can. */ | |
752 | ||
753 | if (WIFSTOPPED (status)) | |
754 | { | |
755 | int signo = target_signal_from_host (WSTOPSIG (status)); | |
756 | ||
757 | if (signal_stop_state (signo) == 0 | |
758 | && signal_print_state (signo) == 0 | |
759 | && signal_pass_state (signo) == 1) | |
760 | { | |
761 | child_resume (GET_LWP (lp->pid), lp->step, signo); | |
762 | lp->stopped = 0; | |
763 | status = 0; | |
764 | goto retry; | |
765 | } | |
766 | } | |
767 | ||
768 | /* This LWP is stopped now. */ | |
769 | lp->stopped = 1; | |
770 | ||
771 | /* Now stop all other LWP's ... */ | |
772 | iterate_over_lwps (stop_callback, NULL); | |
773 | ||
774 | /* ... and wait until all of them have reported back that they're no | |
775 | longer running. */ | |
776 | iterate_over_lwps (stop_wait_callback, NULL); | |
777 | ||
778 | /* If we're not running in "threaded" mode, we'll report the bare | |
779 | process id. */ | |
780 | ||
781 | if (WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP) | |
782 | trap_pid = (threaded ? lp->pid : GET_LWP (lp->pid)); | |
783 | else | |
784 | trap_pid = 0; | |
785 | ||
786 | store_waitstatus (ourstatus, status); | |
787 | return (threaded ? lp->pid : GET_LWP (lp->pid)); | |
788 | } | |
789 | ||
790 | static int | |
791 | kill_callback (struct lwp_info *lp, void *data) | |
792 | { | |
793 | ptrace (PTRACE_KILL, GET_LWP (lp->pid), 0, 0); | |
794 | return 0; | |
795 | } | |
796 | ||
797 | static int | |
798 | kill_wait_callback (struct lwp_info *lp, void *data) | |
799 | { | |
800 | pid_t pid; | |
801 | ||
802 | /* We must make sure that there are no pending events (delayed | |
803 | SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current | |
804 | program doesn't interfere with any following debugging session. */ | |
805 | ||
806 | /* For cloned processes we must check both with __WCLONE and | |
807 | without, since the exit status of a cloned process isn't reported | |
808 | with __WCLONE. */ | |
809 | if (is_cloned (lp->pid)) | |
810 | { | |
811 | do | |
812 | { | |
813 | pid = waitpid (GET_LWP (lp->pid), NULL, __WCLONE); | |
814 | } | |
815 | while (pid == GET_LWP (lp->pid)); | |
816 | ||
817 | gdb_assert (pid == -1 && errno == ECHILD); | |
818 | } | |
819 | ||
820 | do | |
821 | { | |
822 | pid = waitpid (GET_LWP (lp->pid), NULL, 0); | |
823 | } | |
824 | while (pid == GET_LWP (lp->pid)); | |
825 | ||
826 | gdb_assert (pid == -1 && errno == ECHILD); | |
827 | return 0; | |
828 | } | |
829 | ||
830 | static void | |
831 | lin_lwp_kill (void) | |
832 | { | |
833 | /* Kill all LWP's ... */ | |
834 | iterate_over_lwps (kill_callback, NULL); | |
835 | ||
836 | /* ... and wait until we've flushed all events. */ | |
837 | iterate_over_lwps (kill_wait_callback, NULL); | |
838 | ||
839 | target_mourn_inferior (); | |
840 | } | |
841 | ||
842 | static void | |
843 | lin_lwp_create_inferior (char *exec_file, char *allargs, char **env) | |
844 | { | |
845 | struct target_ops *target_beneath; | |
846 | ||
847 | init_lwp_list (); | |
848 | ||
849 | #if 0 | |
850 | target_beneath = find_target_beneath (&lin_lwp_ops); | |
851 | #else | |
852 | target_beneath = &child_ops; | |
853 | #endif | |
854 | target_beneath->to_create_inferior (exec_file, allargs, env); | |
855 | } | |
856 | ||
857 | static void | |
858 | lin_lwp_mourn_inferior (void) | |
859 | { | |
860 | struct target_ops *target_beneath; | |
861 | ||
862 | init_lwp_list (); | |
863 | ||
864 | trap_pid = 0; | |
865 | ||
866 | #if 0 | |
867 | target_beneath = find_target_beneath (&lin_lwp_ops); | |
868 | #else | |
869 | target_beneath = &child_ops; | |
870 | #endif | |
871 | target_beneath->to_mourn_inferior (); | |
872 | } | |
873 | ||
874 | static void | |
875 | lin_lwp_fetch_registers (int regno) | |
876 | { | |
877 | struct cleanup *old_chain = save_inferior_pid (); | |
878 | ||
879 | if (is_lwp (inferior_pid)) | |
880 | inferior_pid = GET_LWP (inferior_pid); | |
881 | ||
882 | fetch_inferior_registers (regno); | |
883 | ||
884 | do_cleanups (old_chain); | |
885 | } | |
886 | ||
887 | static void | |
888 | lin_lwp_store_registers (int regno) | |
889 | { | |
890 | struct cleanup *old_chain = save_inferior_pid (); | |
891 | ||
892 | if (is_lwp (inferior_pid)) | |
893 | inferior_pid = GET_LWP (inferior_pid); | |
894 | ||
895 | store_inferior_registers (regno); | |
896 | ||
897 | do_cleanups (old_chain); | |
898 | } | |
899 | ||
900 | static int | |
901 | lin_lwp_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int write, | |
902 | struct target_ops *target) | |
903 | { | |
904 | struct cleanup *old_chain = save_inferior_pid (); | |
905 | int xfer; | |
906 | ||
907 | if (is_lwp (inferior_pid)) | |
908 | inferior_pid = GET_LWP (inferior_pid); | |
909 | ||
910 | xfer = child_xfer_memory (memaddr, myaddr, len, write, target); | |
911 | ||
912 | do_cleanups (old_chain); | |
913 | return xfer; | |
914 | } | |
915 | ||
916 | static int | |
917 | lin_lwp_thread_alive (int pid) | |
918 | { | |
919 | gdb_assert (is_lwp (pid)); | |
920 | ||
921 | errno = 0; | |
922 | ptrace (PTRACE_PEEKUSER, GET_LWP (pid), 0, 0); | |
923 | if (errno) | |
924 | return 0; | |
925 | ||
926 | return 1; | |
927 | } | |
928 | ||
929 | static char * | |
930 | lin_lwp_pid_to_str (int pid) | |
931 | { | |
932 | static char buf[64]; | |
933 | ||
934 | if (is_lwp (pid)) | |
935 | { | |
936 | snprintf (buf, sizeof (buf), "LWP %d", GET_LWP (pid)); | |
937 | return buf; | |
938 | } | |
939 | ||
940 | return normal_pid_to_str (pid); | |
941 | } | |
942 | ||
943 | static void | |
944 | init_lin_lwp_ops (void) | |
945 | { | |
946 | #if 0 | |
947 | lin_lwp_ops.to_open = lin_lwp_open; | |
948 | #endif | |
949 | lin_lwp_ops.to_shortname = "lwp-layer"; | |
950 | lin_lwp_ops.to_longname = "lwp-layer"; | |
951 | lin_lwp_ops.to_doc = "Low level threads support (LWP layer)"; | |
952 | lin_lwp_ops.to_attach = lin_lwp_attach; | |
953 | lin_lwp_ops.to_detach = lin_lwp_detach; | |
954 | lin_lwp_ops.to_resume = lin_lwp_resume; | |
955 | lin_lwp_ops.to_wait = lin_lwp_wait; | |
956 | lin_lwp_ops.to_fetch_registers = lin_lwp_fetch_registers; | |
957 | lin_lwp_ops.to_store_registers = lin_lwp_store_registers; | |
958 | lin_lwp_ops.to_xfer_memory = lin_lwp_xfer_memory; | |
959 | lin_lwp_ops.to_kill = lin_lwp_kill; | |
960 | lin_lwp_ops.to_create_inferior = lin_lwp_create_inferior; | |
961 | lin_lwp_ops.to_mourn_inferior = lin_lwp_mourn_inferior; | |
962 | lin_lwp_ops.to_thread_alive = lin_lwp_thread_alive; | |
963 | lin_lwp_ops.to_pid_to_str = lin_lwp_pid_to_str; | |
964 | lin_lwp_ops.to_stratum = thread_stratum; | |
965 | lin_lwp_ops.to_has_thread_control = tc_schedlock; | |
966 | lin_lwp_ops.to_magic = OPS_MAGIC; | |
967 | } | |
968 | ||
969 | static void | |
970 | sigchld_handler (int signo) | |
971 | { | |
972 | /* Do nothing. The only reason for this handler is that it allows | |
973 | us to use sigsuspend in lin_lwp_wait above to wait for the | |
974 | arrival of a SIGCHLD. */ | |
975 | } | |
976 | ||
977 | void | |
978 | _initialize_lin_lwp (void) | |
979 | { | |
980 | struct sigaction action; | |
981 | sigset_t mask; | |
982 | ||
983 | extern void thread_db_init (struct target_ops *); | |
984 | ||
985 | init_lin_lwp_ops (); | |
986 | add_target (&lin_lwp_ops); | |
987 | thread_db_init (&lin_lwp_ops); | |
988 | ||
989 | action.sa_handler = sigchld_handler; | |
990 | sigemptyset (&action.sa_mask); | |
991 | action.sa_flags = 0; | |
992 | sigaction (SIGCHLD, &action, NULL); | |
993 | ||
994 | /* We block SIGCHLD throughout this code ... */ | |
995 | sigemptyset (&mask); | |
996 | sigaddset (&mask, SIGCHLD); | |
997 | sigprocmask (SIG_BLOCK, &mask, &suspend_mask); | |
998 | ||
999 | /* ... except during a sigsuspend. */ | |
1000 | sigdelset (&suspend_mask, SIGCHLD); | |
1001 | } | |
1002 | \f | |
1003 | ||
1004 | /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to | |
1005 | the LinuxThreads library and therefore doesn't really belong here. */ | |
1006 | ||
1007 | /* Read variable NAME in the target and return its value if found. | |
1008 | Otherwise return zero. It is assumed that the type of the variable | |
1009 | is `int'. */ | |
1010 | ||
1011 | static int | |
1012 | get_signo (const char *name) | |
1013 | { | |
1014 | struct minimal_symbol *ms; | |
1015 | int signo; | |
1016 | ||
1017 | ms = lookup_minimal_symbol (name, NULL, NULL); | |
1018 | if (ms == NULL) | |
1019 | return 0; | |
1020 | ||
1021 | if (target_read_memory (SYMBOL_VALUE_ADDRESS (ms), (char *) &signo, | |
1022 | sizeof (signo)) != 0) | |
1023 | return 0; | |
1024 | ||
1025 | return signo; | |
1026 | } | |
1027 | ||
1028 | /* Return the set of signals used by the threads library in *SET. */ | |
1029 | ||
1030 | void | |
1031 | lin_thread_get_thread_signals (sigset_t *set) | |
1032 | { | |
1033 | int restart; | |
1034 | int cancel; | |
1035 | ||
1036 | sigemptyset (set); | |
1037 | ||
1038 | restart = get_signo ("__pthread_sig_restart"); | |
1039 | if (restart == 0) | |
1040 | return; | |
1041 | ||
1042 | cancel = get_signo ("__pthread_sig_cancel"); | |
1043 | if (cancel == 0) | |
1044 | return; | |
1045 | ||
1046 | sigaddset (set, restart); | |
1047 | sigaddset (set, cancel); | |
1048 | } |