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fb0e1ba7 | 1 | /* Multi-threaded debugging support for Linux (LWP layer). |
4e052eda | 2 | Copyright 2000, 2001 Free Software Foundation, Inc. |
fb0e1ba7 MK |
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" | |
4e052eda | 32 | #include "regcache.h" |
fb0e1ba7 MK |
33 | |
34 | #define DEBUG 1 | |
35 | ||
36 | #if DEBUG | |
37 | extern const char *strsignal (int sig); | |
38 | #endif | |
39 | ||
40 | /* On Linux there are no real LWP's. The closest thing to LWP's are | |
41 | processes sharing the same VM space. A multi-threaded process is | |
42 | basically a group of such processes. However, such a grouping is | |
43 | almost entirely a user-space issue; the kernel doesn't enforce such | |
44 | a grouping at all (this might change in the future). In general, | |
45 | we'll rely on the threads library (i.e. the LinuxThreads library) | |
46 | to provide such a grouping. | |
47 | ||
48 | It is perfectly well possible to write a multi-threaded application | |
49 | without the assistance of a threads library, by using the clone | |
50 | system call directly. This module should be able to give some | |
51 | rudimentary support for debugging such applications if developers | |
52 | specify the CLONE_PTRACE flag in the clone system call, and are | |
53 | using Linux 2.4 or above. | |
54 | ||
55 | Note that there are some peculiarities in Linux that affect this | |
56 | code: | |
57 | ||
58 | - In general one should specify the __WCLONE flag to waitpid in | |
3f07c44b MK |
59 | order to make it report events for any of the cloned processes |
60 | (and leave it out for the initial process). However, if a cloned | |
61 | process has exited the exit status is only reported if the | |
62 | __WCLONE flag is absent. Linux 2.4 has a __WALL flag, but we | |
63 | cannot use it since GDB must work on older systems too. | |
fb0e1ba7 MK |
64 | |
65 | - When a traced, cloned process exits and is waited for by the | |
4c8de859 | 66 | debugger, the kernel reassigns it to the original parent and |
fb0e1ba7 MK |
67 | keeps it around as a "zombie". Somehow, the LinuxThreads library |
68 | doesn't notice this, which leads to the "zombie problem": When | |
69 | debugged a multi-threaded process that spawns a lot of threads | |
70 | will run out of processes, even if the threads exit, because the | |
71 | "zombies" stay around. */ | |
72 | ||
73 | /* Structure describing a LWP. */ | |
74 | struct lwp_info | |
75 | { | |
76 | /* The process id of the LWP. This is a combination of the LWP id | |
77 | and overall process id. */ | |
78 | int pid; | |
79 | ||
80 | /* Non-zero if we sent this LWP a SIGSTOP (but the LWP didn't report | |
81 | it back yet). */ | |
82 | int signalled; | |
83 | ||
84 | /* Non-zero if this LWP is stopped. */ | |
85 | int stopped; | |
86 | ||
87 | /* If non-zero, a pending wait status. */ | |
88 | int status; | |
89 | ||
90 | /* Non-zero if we were stepping this LWP. */ | |
91 | int step; | |
92 | ||
93 | /* Next LWP in list. */ | |
94 | struct lwp_info *next; | |
95 | }; | |
96 | ||
97 | /* List of known LWPs. */ | |
98 | static struct lwp_info *lwp_list; | |
99 | ||
100 | /* Number of LWPs in the list. */ | |
101 | static int num_lwps; | |
102 | ||
103 | /* Non-zero if we're running in "threaded" mode. */ | |
104 | static int threaded; | |
105 | \f | |
106 | ||
107 | #ifndef TIDGET | |
108 | #define TIDGET(PID) (((PID) & 0x7fffffff) >> 16) | |
109 | #define PIDGET(PID) (((PID) & 0xffff)) | |
110 | #define MERGEPID(PID, TID) (((PID) & 0xffff) | ((TID) << 16)) | |
111 | #endif | |
112 | ||
113 | #define THREAD_FLAG 0x80000000 | |
114 | #define is_lwp(pid) (((pid) & THREAD_FLAG) == 0 && TIDGET (pid)) | |
115 | #define GET_LWP(pid) TIDGET (pid) | |
116 | #define GET_PID(pid) PIDGET (pid) | |
117 | #define BUILD_LWP(tid, pid) MERGEPID (pid, tid) | |
118 | ||
119 | #define is_cloned(pid) (GET_LWP (pid) != GET_PID (pid)) | |
120 | ||
121 | /* If the last reported event was a SIGTRAP, this variable is set to | |
122 | the process id of the LWP/thread that got it. */ | |
123 | int trap_pid; | |
124 | \f | |
125 | ||
126 | /* This module's target-specific operations. */ | |
127 | static struct target_ops lin_lwp_ops; | |
128 | ||
129 | /* The standard child operations. */ | |
130 | extern struct target_ops child_ops; | |
131 | ||
3f07c44b MK |
132 | /* Since we cannot wait (in lin_lwp_wait) for the initial process and |
133 | any cloned processes with a single call to waitpid, we have to use | |
4c8de859 | 134 | the WNOHANG flag and call waitpid in a loop. To optimize |
3f07c44b MK |
135 | things a bit we use `sigsuspend' to wake us up when a process has |
136 | something to report (it will send us a SIGCHLD if it has). To make | |
137 | this work we have to juggle with the signal mask. We save the | |
4c8de859 | 138 | original signal mask such that we can restore it before creating a |
3f07c44b MK |
139 | new process in order to avoid blocking certain signals in the |
140 | inferior. We then block SIGCHLD during the waitpid/sigsuspend | |
141 | loop. */ | |
142 | ||
4c8de859 | 143 | /* Original signal mask. */ |
3f07c44b MK |
144 | static sigset_t normal_mask; |
145 | ||
fb0e1ba7 MK |
146 | /* Signal mask for use with sigsuspend in lin_lwp_wait, initialized in |
147 | _initialize_lin_lwp. */ | |
148 | static sigset_t suspend_mask; | |
3f07c44b MK |
149 | |
150 | /* Signals to block to make that sigsuspend work. */ | |
151 | static sigset_t blocked_mask; | |
fb0e1ba7 MK |
152 | \f |
153 | ||
154 | /* Prototypes for local functions. */ | |
155 | static void lin_lwp_mourn_inferior (void); | |
156 | \f | |
157 | ||
158 | /* Initialize the list of LWPs. */ | |
159 | ||
160 | static void | |
161 | init_lwp_list (void) | |
162 | { | |
163 | struct lwp_info *lp, *lpnext; | |
164 | ||
165 | for (lp = lwp_list; lp; lp = lpnext) | |
166 | { | |
167 | lpnext = lp->next; | |
b8c9b27d | 168 | xfree (lp); |
fb0e1ba7 MK |
169 | } |
170 | ||
171 | lwp_list = NULL; | |
172 | num_lwps = 0; | |
173 | threaded = 0; | |
174 | } | |
175 | ||
176 | /* Add the LWP specified by PID to the list. If this causes the | |
177 | number of LWPs to become larger than one, go into "threaded" mode. | |
178 | Return a pointer to the structure describing the new LWP. */ | |
179 | ||
180 | static struct lwp_info * | |
181 | add_lwp (int pid) | |
182 | { | |
183 | struct lwp_info *lp; | |
184 | ||
185 | gdb_assert (is_lwp (pid)); | |
186 | ||
187 | lp = (struct lwp_info *) xmalloc (sizeof (struct lwp_info)); | |
188 | ||
189 | memset (lp, 0, sizeof (struct lwp_info)); | |
190 | ||
191 | lp->pid = pid; | |
192 | ||
193 | lp->next = lwp_list; | |
194 | lwp_list = lp; | |
195 | if (++num_lwps > 1) | |
196 | threaded = 1; | |
197 | ||
198 | return lp; | |
199 | } | |
200 | ||
201 | /* Remove the LWP specified by PID from the list. */ | |
202 | ||
203 | static void | |
204 | delete_lwp (int pid) | |
205 | { | |
206 | struct lwp_info *lp, *lpprev; | |
207 | ||
208 | lpprev = NULL; | |
209 | ||
210 | for (lp = lwp_list; lp; lpprev = lp, lp = lp->next) | |
211 | if (lp->pid == pid) | |
212 | break; | |
213 | ||
214 | if (!lp) | |
215 | return; | |
216 | ||
217 | /* We don't go back to "non-threaded" mode if the number of threads | |
218 | becomes less than two. */ | |
219 | num_lwps--; | |
220 | ||
221 | if (lpprev) | |
222 | lpprev->next = lp->next; | |
223 | else | |
224 | lwp_list = lp->next; | |
225 | ||
b8c9b27d | 226 | xfree (lp); |
fb0e1ba7 MK |
227 | } |
228 | ||
229 | /* Return a pointer to the structure describing the LWP corresponding | |
230 | to PID. If no corresponding LWP could be found, return NULL. */ | |
231 | ||
232 | static struct lwp_info * | |
233 | find_lwp_pid (int pid) | |
234 | { | |
235 | struct lwp_info *lp; | |
236 | ||
237 | if (is_lwp (pid)) | |
238 | pid = GET_LWP (pid); | |
239 | ||
240 | for (lp = lwp_list; lp; lp = lp->next) | |
241 | if (pid == GET_LWP (lp->pid)) | |
242 | return lp; | |
243 | ||
244 | return NULL; | |
245 | } | |
246 | ||
247 | /* Call CALLBACK with its second argument set to DATA for every LWP in | |
248 | the list. If CALLBACK returns 1 for a particular LWP, return a | |
249 | pointer to the structure describing that LWP immediately. | |
250 | Otherwise return NULL. */ | |
251 | ||
252 | struct lwp_info * | |
253 | iterate_over_lwps (int (*callback) (struct lwp_info *, void *), void *data) | |
254 | { | |
255 | struct lwp_info *lp; | |
256 | ||
257 | for (lp = lwp_list; lp; lp = lp->next) | |
258 | if ((*callback) (lp, data)) | |
259 | return lp; | |
260 | ||
261 | return NULL; | |
262 | } | |
263 | \f | |
264 | ||
265 | /* Helper functions. */ | |
266 | ||
267 | static void | |
268 | restore_inferior_pid (void *arg) | |
269 | { | |
270 | int *saved_pid_ptr = arg; | |
271 | inferior_pid = *saved_pid_ptr; | |
b8c9b27d | 272 | xfree (arg); |
fb0e1ba7 MK |
273 | } |
274 | ||
275 | static struct cleanup * | |
276 | save_inferior_pid (void) | |
277 | { | |
278 | int *saved_pid_ptr; | |
279 | ||
280 | saved_pid_ptr = xmalloc (sizeof (int)); | |
281 | *saved_pid_ptr = inferior_pid; | |
282 | return make_cleanup (restore_inferior_pid, saved_pid_ptr); | |
283 | } | |
284 | \f | |
285 | ||
e02bc4cc DS |
286 | /* Implementation of the PREPARE_TO_PROCEED hook for the Linux LWP |
287 | layer. | |
288 | ||
289 | Note that this implementation is potentially redundant now that | |
290 | default_prepare_to_proceed() has been added. */ | |
fb0e1ba7 MK |
291 | |
292 | int | |
293 | lin_lwp_prepare_to_proceed (void) | |
294 | { | |
295 | if (trap_pid && inferior_pid != trap_pid) | |
296 | { | |
297 | /* Switched over from TRAP_PID. */ | |
298 | CORE_ADDR stop_pc = read_pc (); | |
299 | CORE_ADDR trap_pc; | |
300 | ||
301 | /* Avoid switching where it wouldn't do any good, i.e. if both | |
302 | threads are at the same breakpoint. */ | |
303 | trap_pc = read_pc_pid (trap_pid); | |
304 | if (trap_pc != stop_pc && breakpoint_here_p (trap_pc)) | |
305 | { | |
306 | /* User hasn't deleted the breakpoint. Return non-zero, and | |
307 | switch back to TRAP_PID. */ | |
308 | inferior_pid = trap_pid; | |
309 | ||
310 | /* FIXME: Is this stuff really necessary? */ | |
311 | flush_cached_frames (); | |
312 | registers_changed (); | |
313 | ||
314 | return 1; | |
315 | } | |
316 | } | |
317 | ||
318 | return 0; | |
319 | } | |
320 | \f | |
321 | ||
322 | #if 0 | |
323 | static void | |
324 | lin_lwp_open (char *args, int from_tty) | |
325 | { | |
326 | push_target (&lin_lwp_ops); | |
327 | } | |
328 | #endif | |
329 | ||
330 | /* Attach to the LWP specified by PID. If VERBOSE is non-zero, print | |
331 | a message telling the user that a new LWP has been added to the | |
332 | process. */ | |
333 | ||
334 | void | |
335 | lin_lwp_attach_lwp (int pid, int verbose) | |
336 | { | |
337 | struct lwp_info *lp; | |
338 | ||
339 | gdb_assert (is_lwp (pid)); | |
340 | ||
341 | if (verbose) | |
342 | printf_filtered ("[New %s]\n", target_pid_to_str (pid)); | |
343 | ||
344 | if (ptrace (PTRACE_ATTACH, GET_LWP (pid), 0, 0) < 0) | |
345 | error ("Can't attach %s: %s", target_pid_to_str (pid), strerror (errno)); | |
346 | ||
347 | lp = add_lwp (pid); | |
348 | lp->signalled = 1; | |
349 | } | |
350 | ||
351 | static void | |
352 | lin_lwp_attach (char *args, int from_tty) | |
353 | { | |
354 | /* FIXME: We should probably accept a list of process id's, and | |
355 | attach all of them. */ | |
356 | error("Not implemented yet"); | |
357 | } | |
358 | ||
359 | static void | |
360 | lin_lwp_detach (char *args, int from_tty) | |
361 | { | |
362 | /* FIXME: Provide implementation when we implement lin_lwp_attach. */ | |
363 | error ("Not implemented yet"); | |
364 | } | |
365 | \f | |
366 | ||
367 | struct private_thread_info | |
368 | { | |
369 | int lwpid; | |
370 | }; | |
371 | ||
372 | /* Return non-zero if TP corresponds to the LWP specified by DATA | |
373 | (which is assumed to be a pointer to a `struct lwp_info'. */ | |
374 | ||
375 | static int | |
376 | find_lwp_callback (struct thread_info *tp, void *data) | |
377 | { | |
378 | struct lwp_info *lp = data; | |
379 | ||
380 | if (tp->private->lwpid == GET_LWP (lp->pid)) | |
381 | return 1; | |
382 | ||
383 | return 0; | |
384 | } | |
385 | ||
386 | /* Resume LP. */ | |
387 | ||
388 | static int | |
389 | resume_callback (struct lwp_info *lp, void *data) | |
390 | { | |
391 | if (lp->stopped && lp->status == 0) | |
392 | { | |
393 | struct thread_info *tp; | |
394 | ||
395 | #if 1 | |
396 | /* FIXME: kettenis/2000-08-26: This should really be handled | |
397 | properly by core GDB. */ | |
398 | ||
399 | tp = find_thread_pid (lp->pid); | |
400 | if (tp == NULL) | |
401 | tp = iterate_over_threads (find_lwp_callback, lp); | |
402 | gdb_assert (tp); | |
403 | ||
404 | /* If we were previously stepping the thread, and now continue | |
405 | the thread we must invalidate the stepping range. However, | |
406 | if there is a step_resume breakpoint for this thread, we must | |
407 | preserve the stepping range to make it possible to continue | |
408 | stepping once we hit it. */ | |
409 | if (tp->step_range_end && tp->step_resume_breakpoint == NULL) | |
410 | { | |
411 | gdb_assert (lp->step); | |
412 | tp->step_range_start = tp->step_range_end = 0; | |
413 | } | |
414 | #endif | |
415 | ||
416 | child_resume (GET_LWP (lp->pid), 0, TARGET_SIGNAL_0); | |
417 | lp->stopped = 0; | |
418 | lp->step = 0; | |
419 | } | |
420 | ||
421 | return 0; | |
422 | } | |
423 | ||
424 | static void | |
425 | lin_lwp_resume (int pid, int step, enum target_signal signo) | |
426 | { | |
427 | struct lwp_info *lp; | |
428 | int resume_all; | |
429 | ||
430 | /* Apparently the interpretation of PID is dependent on STEP: If | |
431 | STEP is non-zero, a specific PID means `step only this process | |
432 | id'. But if STEP is zero, then PID means `continue *all* | |
433 | processes, but give the signal only to this one'. */ | |
434 | resume_all = (pid == -1) || !step; | |
435 | ||
436 | /* If PID is -1, it's the current inferior that should be | |
437 | handled special. */ | |
438 | if (pid == -1) | |
439 | pid = inferior_pid; | |
440 | ||
441 | lp = find_lwp_pid (pid); | |
442 | if (lp) | |
443 | { | |
444 | pid = GET_LWP (lp->pid); | |
445 | ||
fb0e1ba7 MK |
446 | /* Remember if we're stepping. */ |
447 | lp->step = step; | |
448 | ||
449 | /* If we have a pending wait status for this thread, there is no | |
450 | point in resuming the process. */ | |
451 | if (lp->status) | |
452 | { | |
453 | /* FIXME: What should we do if we are supposed to continue | |
454 | this thread with a signal? */ | |
455 | gdb_assert (signo == TARGET_SIGNAL_0); | |
456 | return; | |
457 | } | |
40564aca MK |
458 | |
459 | /* Mark LWP as not stopped to prevent it from being continued by | |
460 | resume_callback. */ | |
461 | lp->stopped = 0; | |
fb0e1ba7 MK |
462 | } |
463 | ||
464 | if (resume_all) | |
465 | iterate_over_lwps (resume_callback, NULL); | |
466 | ||
467 | child_resume (pid, step, signo); | |
468 | } | |
469 | \f | |
470 | ||
471 | /* Send a SIGSTOP to LP. */ | |
472 | ||
473 | static int | |
474 | stop_callback (struct lwp_info *lp, void *data) | |
475 | { | |
476 | if (! lp->stopped && ! lp->signalled) | |
477 | { | |
478 | int ret; | |
479 | ||
480 | ret = kill (GET_LWP (lp->pid), SIGSTOP); | |
481 | gdb_assert (ret == 0); | |
482 | ||
483 | lp->signalled = 1; | |
484 | gdb_assert (lp->status == 0); | |
485 | } | |
486 | ||
487 | return 0; | |
488 | } | |
489 | ||
490 | /* Wait until LP is stopped. */ | |
491 | ||
492 | static int | |
493 | stop_wait_callback (struct lwp_info *lp, void *data) | |
494 | { | |
495 | if (! lp->stopped && lp->signalled) | |
496 | { | |
497 | pid_t pid; | |
498 | int status; | |
499 | ||
500 | gdb_assert (lp->status == 0); | |
501 | ||
502 | pid = waitpid (GET_LWP (lp->pid), &status, | |
503 | is_cloned (lp->pid) ? __WCLONE : 0); | |
504 | if (pid == -1 && errno == ECHILD) | |
505 | /* OK, the proccess has disappeared. We'll catch the actual | |
3f07c44b | 506 | exit event in lin_lwp_wait. */ |
fb0e1ba7 MK |
507 | return 0; |
508 | ||
509 | gdb_assert (pid == GET_LWP (lp->pid)); | |
510 | ||
511 | if (WIFEXITED (status) || WIFSIGNALED (status)) | |
512 | { | |
513 | gdb_assert (num_lwps > 1); | |
fb0e1ba7 | 514 | |
e6328671 MK |
515 | if (in_thread_list (lp->pid)) |
516 | { | |
517 | /* Core GDB cannot deal with us deleting the current | |
518 | thread. */ | |
519 | if (lp->pid != inferior_pid) | |
520 | delete_thread (lp->pid); | |
521 | printf_unfiltered ("[%s exited]\n", | |
522 | target_pid_to_str (lp->pid)); | |
523 | } | |
524 | #if DEBUG | |
525 | printf ("%s exited.\n", target_pid_to_str (lp->pid)); | |
526 | #endif | |
fb0e1ba7 MK |
527 | delete_lwp (lp->pid); |
528 | return 0; | |
529 | } | |
530 | ||
531 | gdb_assert (WIFSTOPPED (status)); | |
532 | lp->stopped = 1; | |
533 | ||
534 | if (WSTOPSIG (status) != SIGSTOP) | |
535 | { | |
536 | if (WSTOPSIG (status) == SIGTRAP | |
537 | && breakpoint_inserted_here_p (read_pc_pid (pid) | |
538 | - DECR_PC_AFTER_BREAK)) | |
539 | { | |
540 | /* If a LWP other than the LWP that we're reporting an | |
541 | event for has hit a GDB breakpoint (as opposed to | |
542 | some random trap signal), then just arrange for it to | |
543 | hit it again later. We don't keep the SIGTRAP status | |
544 | and don't forward the SIGTRAP signal to the LWP. We | |
545 | will handle the current event, eventually we will | |
546 | resume all LWPs, and this one will get its breakpoint | |
547 | trap again. | |
548 | ||
549 | If we do not do this, then we run the risk that the | |
550 | user will delete or disable the breakpoint, but the | |
551 | thread will have already tripped on it. */ | |
552 | #if DEBUG | |
553 | printf ("Tripped breakpoint at %lx in LWP %d" | |
554 | " while waiting for SIGSTOP.\n", | |
555 | (long) read_pc_pid (lp->pid), pid); | |
556 | #endif | |
557 | /* Set the PC to before the trap. */ | |
558 | if (DECR_PC_AFTER_BREAK) | |
559 | write_pc_pid (read_pc_pid (pid) - DECR_PC_AFTER_BREAK, pid); | |
560 | } | |
561 | else | |
562 | { | |
563 | #if DEBUG | |
564 | printf ("Received %s in LWP %d while waiting for SIGSTOP.\n", | |
565 | strsignal (WSTOPSIG (status)), pid); | |
566 | #endif | |
567 | /* The thread was stopped with a signal other than | |
568 | SIGSTOP, and didn't accidentiliy trip a breakpoint. | |
569 | Record the wait status. */ | |
570 | lp->status = status; | |
571 | } | |
572 | } | |
573 | else | |
574 | { | |
575 | /* We caught the SIGSTOP that we intended to catch, so | |
576 | there's no SIGSTOP pending. */ | |
577 | lp->signalled = 0; | |
578 | } | |
579 | } | |
580 | ||
581 | return 0; | |
582 | } | |
583 | ||
584 | /* Return non-zero if LP has a wait status pending. */ | |
585 | ||
586 | static int | |
587 | status_callback (struct lwp_info *lp, void *data) | |
588 | { | |
589 | return (lp->status != 0); | |
590 | } | |
591 | ||
592 | /* Return non-zero if LP isn't stopped. */ | |
593 | ||
594 | static int | |
595 | running_callback (struct lwp_info *lp, void *data) | |
596 | { | |
597 | return (lp->stopped == 0); | |
598 | } | |
599 | ||
600 | static int | |
601 | lin_lwp_wait (int pid, struct target_waitstatus *ourstatus) | |
602 | { | |
603 | struct lwp_info *lp = NULL; | |
604 | int options = 0; | |
605 | int status = 0; | |
606 | ||
3f07c44b MK |
607 | /* Make sure SIGCHLD is blocked. */ |
608 | if (! sigismember (&blocked_mask, SIGCHLD)) | |
609 | { | |
610 | sigaddset (&blocked_mask, SIGCHLD); | |
611 | sigprocmask (SIG_BLOCK, &blocked_mask, NULL); | |
612 | } | |
613 | ||
fb0e1ba7 MK |
614 | retry: |
615 | ||
616 | /* First check if there is a LWP with a wait status pending. */ | |
617 | if (pid == -1) | |
618 | { | |
619 | /* Any LWP will do. */ | |
620 | lp = iterate_over_lwps (status_callback, NULL); | |
621 | if (lp) | |
622 | { | |
623 | #if DEBUG | |
624 | printf ("Using pending wait status for LWP %d.\n", | |
625 | GET_LWP (lp->pid)); | |
626 | #endif | |
627 | status = lp->status; | |
628 | lp->status = 0; | |
629 | } | |
630 | ||
631 | /* But if we don't fine one, we'll have to wait, and check both | |
632 | cloned and uncloned processes. We start with the cloned | |
633 | processes. */ | |
634 | options = __WCLONE | WNOHANG; | |
635 | } | |
636 | else if (is_lwp (pid)) | |
637 | { | |
638 | #if DEBUG | |
639 | printf ("Waiting for specific LWP %d.\n", GET_LWP (pid)); | |
640 | #endif | |
641 | /* We have a specific LWP to check. */ | |
642 | lp = find_lwp_pid (GET_LWP (pid)); | |
643 | gdb_assert (lp); | |
644 | status = lp->status; | |
645 | lp->status = 0; | |
646 | #if DEBUG | |
647 | if (status) | |
648 | printf ("Using pending wait status for LWP %d.\n", | |
649 | GET_LWP (lp->pid)); | |
650 | #endif | |
651 | ||
652 | /* If we have to wait, take into account whether PID is a cloned | |
653 | process or not. And we have to convert it to something that | |
654 | the layer beneath us can understand. */ | |
655 | options = is_cloned (lp->pid) ? __WCLONE : 0; | |
656 | pid = GET_LWP (pid); | |
657 | } | |
658 | ||
659 | if (status && lp->signalled) | |
660 | { | |
661 | /* A pending SIGSTOP may interfere with the normal stream of | |
662 | events. In a typical case where interference is a problem, | |
663 | we have a SIGSTOP signal pending for LWP A while | |
664 | single-stepping it, encounter an event in LWP B, and take the | |
665 | pending SIGSTOP while trying to stop LWP A. After processing | |
666 | the event in LWP B, LWP A is continued, and we'll never see | |
667 | the SIGTRAP associated with the last time we were | |
668 | single-stepping LWP A. */ | |
669 | ||
670 | /* Resume the thread. It should halt immediately returning the | |
671 | pending SIGSTOP. */ | |
672 | child_resume (GET_LWP (lp->pid), lp->step, TARGET_SIGNAL_0); | |
673 | lp->stopped = 0; | |
674 | ||
675 | /* This should catch the pending SIGSTOP. */ | |
676 | stop_wait_callback (lp, NULL); | |
677 | } | |
678 | ||
679 | set_sigint_trap (); /* Causes SIGINT to be passed on to the | |
680 | attached process. */ | |
681 | set_sigio_trap (); | |
682 | ||
683 | while (status == 0) | |
684 | { | |
685 | pid_t lwpid; | |
686 | ||
687 | lwpid = waitpid (pid, &status, options); | |
688 | if (lwpid > 0) | |
689 | { | |
690 | gdb_assert (pid == -1 || lwpid == pid); | |
691 | ||
692 | lp = find_lwp_pid (lwpid); | |
693 | if (! lp) | |
694 | { | |
695 | lp = add_lwp (BUILD_LWP (lwpid, inferior_pid)); | |
696 | if (threaded) | |
697 | { | |
3f07c44b MK |
698 | gdb_assert (WIFSTOPPED (status) |
699 | && WSTOPSIG (status) == SIGSTOP); | |
fb0e1ba7 MK |
700 | lp->signalled = 1; |
701 | ||
702 | if (! in_thread_list (inferior_pid)) | |
703 | { | |
704 | inferior_pid = BUILD_LWP (inferior_pid, inferior_pid); | |
705 | add_thread (inferior_pid); | |
706 | } | |
707 | ||
708 | add_thread (lp->pid); | |
709 | printf_unfiltered ("[New %s]\n", | |
710 | target_pid_to_str (lp->pid)); | |
711 | } | |
712 | } | |
713 | ||
714 | /* Make sure we don't report a TARGET_WAITKIND_EXITED or | |
715 | TARGET_WAITKIND_SIGNALLED event if there are still LWP's | |
716 | left in the process. */ | |
717 | if ((WIFEXITED (status) || WIFSIGNALED (status)) && num_lwps > 1) | |
718 | { | |
719 | if (in_thread_list (lp->pid)) | |
720 | { | |
e6328671 | 721 | /* Core GDB cannot deal with us deleting the current |
fb0e1ba7 MK |
722 | thread. */ |
723 | if (lp->pid != inferior_pid) | |
724 | delete_thread (lp->pid); | |
725 | printf_unfiltered ("[%s exited]\n", | |
726 | target_pid_to_str (lp->pid)); | |
727 | } | |
728 | #if DEBUG | |
729 | printf ("%s exited.\n", target_pid_to_str (lp->pid)); | |
730 | #endif | |
731 | delete_lwp (lp->pid); | |
732 | ||
733 | /* Make sure there is at least one thread running. */ | |
734 | gdb_assert (iterate_over_lwps (running_callback, NULL)); | |
735 | ||
736 | /* Discard the event. */ | |
737 | status = 0; | |
738 | continue; | |
739 | } | |
740 | ||
741 | /* Make sure we don't report a SIGSTOP that we sent | |
742 | ourselves in an attempt to stop an LWP. */ | |
743 | if (lp->signalled && WIFSTOPPED (status) | |
744 | && WSTOPSIG (status) == SIGSTOP) | |
745 | { | |
746 | #if DEBUG | |
747 | printf ("Delayed SIGSTOP caught for %s.\n", | |
748 | target_pid_to_str (lp->pid)); | |
749 | #endif | |
750 | /* This is a delayed SIGSTOP. */ | |
751 | lp->signalled = 0; | |
752 | ||
753 | child_resume (GET_LWP (lp->pid), lp->step, TARGET_SIGNAL_0); | |
754 | lp->stopped = 0; | |
755 | ||
756 | /* Discard the event. */ | |
757 | status = 0; | |
758 | continue; | |
759 | } | |
760 | ||
761 | break; | |
762 | } | |
763 | ||
764 | if (pid == -1) | |
765 | { | |
766 | /* Alternate between checking cloned and uncloned processes. */ | |
767 | options ^= __WCLONE; | |
768 | ||
769 | /* And suspend every time we have checked both. */ | |
770 | if (options & __WCLONE) | |
771 | sigsuspend (&suspend_mask); | |
772 | } | |
773 | ||
774 | /* We shouldn't end up here unless we want to try again. */ | |
775 | gdb_assert (status == 0); | |
776 | } | |
777 | ||
778 | clear_sigio_trap (); | |
779 | clear_sigint_trap (); | |
780 | ||
781 | gdb_assert (lp); | |
782 | ||
783 | /* Don't report signals that GDB isn't interested in, such as | |
784 | signals that are neither printed nor stopped upon. Stopping all | |
785 | threads can be a bit time-consuming so if we want decent | |
786 | performance with heavily multi-threaded programs, especially when | |
787 | they're using a high frequency timer, we'd better avoid it if we | |
788 | can. */ | |
789 | ||
790 | if (WIFSTOPPED (status)) | |
791 | { | |
792 | int signo = target_signal_from_host (WSTOPSIG (status)); | |
793 | ||
794 | if (signal_stop_state (signo) == 0 | |
795 | && signal_print_state (signo) == 0 | |
796 | && signal_pass_state (signo) == 1) | |
797 | { | |
798 | child_resume (GET_LWP (lp->pid), lp->step, signo); | |
799 | lp->stopped = 0; | |
800 | status = 0; | |
801 | goto retry; | |
802 | } | |
803 | } | |
804 | ||
805 | /* This LWP is stopped now. */ | |
806 | lp->stopped = 1; | |
807 | ||
808 | /* Now stop all other LWP's ... */ | |
809 | iterate_over_lwps (stop_callback, NULL); | |
810 | ||
811 | /* ... and wait until all of them have reported back that they're no | |
812 | longer running. */ | |
813 | iterate_over_lwps (stop_wait_callback, NULL); | |
814 | ||
815 | /* If we're not running in "threaded" mode, we'll report the bare | |
816 | process id. */ | |
817 | ||
818 | if (WIFSTOPPED (status) && WSTOPSIG (status) == SIGTRAP) | |
819 | trap_pid = (threaded ? lp->pid : GET_LWP (lp->pid)); | |
820 | else | |
821 | trap_pid = 0; | |
822 | ||
823 | store_waitstatus (ourstatus, status); | |
824 | return (threaded ? lp->pid : GET_LWP (lp->pid)); | |
825 | } | |
826 | ||
827 | static int | |
828 | kill_callback (struct lwp_info *lp, void *data) | |
829 | { | |
830 | ptrace (PTRACE_KILL, GET_LWP (lp->pid), 0, 0); | |
831 | return 0; | |
832 | } | |
833 | ||
834 | static int | |
835 | kill_wait_callback (struct lwp_info *lp, void *data) | |
836 | { | |
837 | pid_t pid; | |
838 | ||
839 | /* We must make sure that there are no pending events (delayed | |
840 | SIGSTOPs, pending SIGTRAPs, etc.) to make sure the current | |
841 | program doesn't interfere with any following debugging session. */ | |
842 | ||
843 | /* For cloned processes we must check both with __WCLONE and | |
844 | without, since the exit status of a cloned process isn't reported | |
845 | with __WCLONE. */ | |
846 | if (is_cloned (lp->pid)) | |
847 | { | |
848 | do | |
849 | { | |
850 | pid = waitpid (GET_LWP (lp->pid), NULL, __WCLONE); | |
851 | } | |
852 | while (pid == GET_LWP (lp->pid)); | |
853 | ||
854 | gdb_assert (pid == -1 && errno == ECHILD); | |
855 | } | |
856 | ||
857 | do | |
858 | { | |
859 | pid = waitpid (GET_LWP (lp->pid), NULL, 0); | |
860 | } | |
861 | while (pid == GET_LWP (lp->pid)); | |
862 | ||
863 | gdb_assert (pid == -1 && errno == ECHILD); | |
864 | return 0; | |
865 | } | |
866 | ||
867 | static void | |
868 | lin_lwp_kill (void) | |
869 | { | |
870 | /* Kill all LWP's ... */ | |
871 | iterate_over_lwps (kill_callback, NULL); | |
872 | ||
873 | /* ... and wait until we've flushed all events. */ | |
874 | iterate_over_lwps (kill_wait_callback, NULL); | |
875 | ||
876 | target_mourn_inferior (); | |
877 | } | |
878 | ||
879 | static void | |
880 | lin_lwp_create_inferior (char *exec_file, char *allargs, char **env) | |
881 | { | |
882 | struct target_ops *target_beneath; | |
883 | ||
884 | init_lwp_list (); | |
885 | ||
886 | #if 0 | |
887 | target_beneath = find_target_beneath (&lin_lwp_ops); | |
888 | #else | |
889 | target_beneath = &child_ops; | |
890 | #endif | |
891 | target_beneath->to_create_inferior (exec_file, allargs, env); | |
892 | } | |
893 | ||
894 | static void | |
895 | lin_lwp_mourn_inferior (void) | |
896 | { | |
897 | struct target_ops *target_beneath; | |
898 | ||
899 | init_lwp_list (); | |
900 | ||
901 | trap_pid = 0; | |
902 | ||
4c8de859 | 903 | /* Restore the original signal mask. */ |
3f07c44b MK |
904 | sigprocmask (SIG_SETMASK, &normal_mask, NULL); |
905 | sigemptyset (&blocked_mask); | |
906 | ||
fb0e1ba7 MK |
907 | #if 0 |
908 | target_beneath = find_target_beneath (&lin_lwp_ops); | |
909 | #else | |
910 | target_beneath = &child_ops; | |
911 | #endif | |
912 | target_beneath->to_mourn_inferior (); | |
913 | } | |
914 | ||
915 | static void | |
916 | lin_lwp_fetch_registers (int regno) | |
917 | { | |
918 | struct cleanup *old_chain = save_inferior_pid (); | |
919 | ||
920 | if (is_lwp (inferior_pid)) | |
921 | inferior_pid = GET_LWP (inferior_pid); | |
922 | ||
923 | fetch_inferior_registers (regno); | |
924 | ||
925 | do_cleanups (old_chain); | |
926 | } | |
927 | ||
928 | static void | |
929 | lin_lwp_store_registers (int regno) | |
930 | { | |
931 | struct cleanup *old_chain = save_inferior_pid (); | |
932 | ||
933 | if (is_lwp (inferior_pid)) | |
934 | inferior_pid = GET_LWP (inferior_pid); | |
935 | ||
936 | store_inferior_registers (regno); | |
937 | ||
938 | do_cleanups (old_chain); | |
939 | } | |
940 | ||
941 | static int | |
942 | lin_lwp_xfer_memory (CORE_ADDR memaddr, char *myaddr, int len, int write, | |
e5da8f38 | 943 | struct mem_attrib *attrib, |
fb0e1ba7 MK |
944 | struct target_ops *target) |
945 | { | |
946 | struct cleanup *old_chain = save_inferior_pid (); | |
947 | int xfer; | |
948 | ||
949 | if (is_lwp (inferior_pid)) | |
950 | inferior_pid = GET_LWP (inferior_pid); | |
951 | ||
e5da8f38 | 952 | xfer = child_xfer_memory (memaddr, myaddr, len, write, attrib, target); |
fb0e1ba7 MK |
953 | |
954 | do_cleanups (old_chain); | |
955 | return xfer; | |
956 | } | |
957 | ||
958 | static int | |
959 | lin_lwp_thread_alive (int pid) | |
960 | { | |
961 | gdb_assert (is_lwp (pid)); | |
962 | ||
963 | errno = 0; | |
964 | ptrace (PTRACE_PEEKUSER, GET_LWP (pid), 0, 0); | |
965 | if (errno) | |
966 | return 0; | |
967 | ||
968 | return 1; | |
969 | } | |
970 | ||
971 | static char * | |
972 | lin_lwp_pid_to_str (int pid) | |
973 | { | |
974 | static char buf[64]; | |
975 | ||
976 | if (is_lwp (pid)) | |
977 | { | |
978 | snprintf (buf, sizeof (buf), "LWP %d", GET_LWP (pid)); | |
979 | return buf; | |
980 | } | |
981 | ||
982 | return normal_pid_to_str (pid); | |
983 | } | |
984 | ||
985 | static void | |
986 | init_lin_lwp_ops (void) | |
987 | { | |
988 | #if 0 | |
989 | lin_lwp_ops.to_open = lin_lwp_open; | |
990 | #endif | |
991 | lin_lwp_ops.to_shortname = "lwp-layer"; | |
992 | lin_lwp_ops.to_longname = "lwp-layer"; | |
993 | lin_lwp_ops.to_doc = "Low level threads support (LWP layer)"; | |
994 | lin_lwp_ops.to_attach = lin_lwp_attach; | |
995 | lin_lwp_ops.to_detach = lin_lwp_detach; | |
996 | lin_lwp_ops.to_resume = lin_lwp_resume; | |
997 | lin_lwp_ops.to_wait = lin_lwp_wait; | |
998 | lin_lwp_ops.to_fetch_registers = lin_lwp_fetch_registers; | |
999 | lin_lwp_ops.to_store_registers = lin_lwp_store_registers; | |
1000 | lin_lwp_ops.to_xfer_memory = lin_lwp_xfer_memory; | |
1001 | lin_lwp_ops.to_kill = lin_lwp_kill; | |
1002 | lin_lwp_ops.to_create_inferior = lin_lwp_create_inferior; | |
1003 | lin_lwp_ops.to_mourn_inferior = lin_lwp_mourn_inferior; | |
1004 | lin_lwp_ops.to_thread_alive = lin_lwp_thread_alive; | |
1005 | lin_lwp_ops.to_pid_to_str = lin_lwp_pid_to_str; | |
1006 | lin_lwp_ops.to_stratum = thread_stratum; | |
1007 | lin_lwp_ops.to_has_thread_control = tc_schedlock; | |
1008 | lin_lwp_ops.to_magic = OPS_MAGIC; | |
1009 | } | |
1010 | ||
1011 | static void | |
1012 | sigchld_handler (int signo) | |
1013 | { | |
1014 | /* Do nothing. The only reason for this handler is that it allows | |
1015 | us to use sigsuspend in lin_lwp_wait above to wait for the | |
1016 | arrival of a SIGCHLD. */ | |
1017 | } | |
1018 | ||
1019 | void | |
1020 | _initialize_lin_lwp (void) | |
1021 | { | |
1022 | struct sigaction action; | |
fb0e1ba7 MK |
1023 | |
1024 | extern void thread_db_init (struct target_ops *); | |
1025 | ||
1026 | init_lin_lwp_ops (); | |
1027 | add_target (&lin_lwp_ops); | |
1028 | thread_db_init (&lin_lwp_ops); | |
1029 | ||
4c8de859 | 1030 | /* Save the original signal mask. */ |
3f07c44b MK |
1031 | sigprocmask (SIG_SETMASK, NULL, &normal_mask); |
1032 | ||
fb0e1ba7 MK |
1033 | action.sa_handler = sigchld_handler; |
1034 | sigemptyset (&action.sa_mask); | |
1035 | action.sa_flags = 0; | |
1036 | sigaction (SIGCHLD, &action, NULL); | |
1037 | ||
3f07c44b MK |
1038 | /* Make sure we don't block SIGCHLD during a sigsuspend. */ |
1039 | sigprocmask (SIG_SETMASK, NULL, &suspend_mask); | |
fb0e1ba7 | 1040 | sigdelset (&suspend_mask, SIGCHLD); |
3f07c44b MK |
1041 | |
1042 | sigemptyset (&blocked_mask); | |
fb0e1ba7 MK |
1043 | } |
1044 | \f | |
1045 | ||
1046 | /* FIXME: kettenis/2000-08-26: The stuff on this page is specific to | |
1047 | the LinuxThreads library and therefore doesn't really belong here. */ | |
1048 | ||
1049 | /* Read variable NAME in the target and return its value if found. | |
1050 | Otherwise return zero. It is assumed that the type of the variable | |
1051 | is `int'. */ | |
1052 | ||
1053 | static int | |
1054 | get_signo (const char *name) | |
1055 | { | |
1056 | struct minimal_symbol *ms; | |
1057 | int signo; | |
1058 | ||
1059 | ms = lookup_minimal_symbol (name, NULL, NULL); | |
1060 | if (ms == NULL) | |
1061 | return 0; | |
1062 | ||
1063 | if (target_read_memory (SYMBOL_VALUE_ADDRESS (ms), (char *) &signo, | |
1064 | sizeof (signo)) != 0) | |
1065 | return 0; | |
1066 | ||
1067 | return signo; | |
1068 | } | |
1069 | ||
1070 | /* Return the set of signals used by the threads library in *SET. */ | |
1071 | ||
1072 | void | |
1073 | lin_thread_get_thread_signals (sigset_t *set) | |
1074 | { | |
3f07c44b MK |
1075 | struct sigaction action; |
1076 | int restart, cancel; | |
fb0e1ba7 MK |
1077 | |
1078 | sigemptyset (set); | |
1079 | ||
1080 | restart = get_signo ("__pthread_sig_restart"); | |
1081 | if (restart == 0) | |
1082 | return; | |
1083 | ||
1084 | cancel = get_signo ("__pthread_sig_cancel"); | |
1085 | if (cancel == 0) | |
1086 | return; | |
1087 | ||
1088 | sigaddset (set, restart); | |
1089 | sigaddset (set, cancel); | |
3f07c44b MK |
1090 | |
1091 | /* The LinuxThreads library makes terminating threads send a special | |
1092 | "cancel" signal instead of SIGCHLD. Make sure we catch those (to | |
1093 | prevent them from terminating GDB itself, which is likely to be | |
1094 | their default action) and treat them the same way as SIGCHLD. */ | |
1095 | ||
1096 | action.sa_handler = sigchld_handler; | |
1097 | sigemptyset (&action.sa_mask); | |
1098 | action.sa_flags = 0; | |
1099 | sigaction (cancel, &action, NULL); | |
1100 | ||
1101 | /* We block the "cancel" signal throughout this code ... */ | |
1102 | sigaddset (&blocked_mask, cancel); | |
1103 | sigprocmask (SIG_BLOCK, &blocked_mask, NULL); | |
1104 | ||
1105 | /* ... except during a sigsuspend. */ | |
1106 | sigdelset (&suspend_mask, cancel); | |
fb0e1ba7 | 1107 | } |