| blob | 37df561de0b6089a3678cc7091389652a3ff38dd |
1 /* Target-struct-independent code to start (run) and stop an inferior
2 process.
4 Copyright (C) 1986-2019 Free Software Foundation, Inc.
6 This file is part of GDB.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>. */
23 #include <ctype.h>
37 #include <signal.h>
73 /* Prototypes for local functions */
99 /* Asynchronous signal handler registered as event loop source for
100 when we have pending events ready to be passed to the core. */
103 /* Stores whether infrun_async was previously enabled or disabled.
104 Starts off as -1, indicating "never enabled/disabled". */
107 /* See infrun.h. */
109 void
111 {
113 {
119 enable);
123 else
125 }
126 }
128 /* See infrun.h. */
130 void
132 {
134 }
136 /* When set, stop the 'step' command if we enter a function which has
137 no line number information. The normal behavior is that we step
138 over such function. */
140 static void
143 {
145 }
147 /* proceed and normal_stop use this to notify the user when the
148 inferior stopped in a different thread than it had been running
149 in. */
153 /* If set (default for legacy reasons), when following a fork, GDB
154 will detach from one of the fork branches, child or parent.
155 Exactly which branch is detached depends on 'set follow-fork-mode'
156 setting. */
161 static void
164 {
166 }
169 static void
172 {
174 }
177 /* Support for disabling address space randomization. */
181 static void
184 {
189 value);
190 else
194 }
196 static void
199 {
204 }
206 /* User interface for non-stop mode. */
211 static void
214 {
216 {
219 }
222 }
224 static void
227 {
230 value);
231 }
233 /* "Observer mode" is somewhat like a more extreme version of
234 non-stop, in which all GDB operations that might affect the
235 target's execution have been disabled. */
240 static void
243 {
245 {
248 }
256 /* We can insert fast tracepoints in or out of observer mode,
257 but enable them if we're going into this mode. */
263 /* Going *into* observer mode we must force non-stop, then
264 going out we leave it that way. */
266 {
269 }
274 }
276 static void
279 {
281 }
283 /* This updates the value of observer mode based on changes in
284 permissions. Note that we are deliberately ignoring the values of
285 may-write-registers and may-write-memory, since the user may have
286 reason to enable these during a session, for instance to turn on a
287 debugging-related global. */
289 void
291 {
294 newval = (!may_insert_breakpoints
295 && !may_insert_tracepoints
296 && may_insert_fast_tracepoints
297 && !may_stop
300 /* Let the user know if things change. */
306 }
308 /* Tables of how to react to signals; the user sets them. */
314 /* Table of signals that are registered with "catch signal". A
315 non-zero entry indicates that the signal is caught by some "catch
316 signal" command. */
319 /* Table of signals that the target may silently handle.
320 This is automatically determined from the flags above,
321 and simply cached here. */
324 #define SET_SIGS(nsigs,sigs,flags) \
325 do { \
326 int signum = (nsigs); \
327 while (signum-- > 0) \
328 if ((sigs)[signum]) \
329 (flags)[signum] = 1; \
330 } while (0)
332 #define UNSET_SIGS(nsigs,sigs,flags) \
333 do { \
334 int signum = (nsigs); \
335 while (signum-- > 0) \
336 if ((sigs)[signum]) \
337 (flags)[signum] = 0; \
338 } while (0)
340 /* Update the target's copy of SIGNAL_PROGRAM. The sole purpose of
341 this function is to avoid exporting `signal_program'. */
343 void
345 {
347 }
349 /* Value to pass to target_resume() to cause all threads to resume. */
351 #define RESUME_ALL minus_one_ptid
353 /* Command list pointer for the "stop" placeholder. */
357 /* Nonzero if we want to give control to the user when we're notified
358 of shared library events by the dynamic linker. */
361 /* Enable or disable optional shared library event breakpoints
362 as appropriate when the above flag is changed. */
364 static void
367 {
369 }
371 static void
374 {
376 value);
377 }
379 /* Nonzero after stop if current stack frame should be printed. */
383 /* This is a cached copy of the pid/waitstatus of the last event
384 returned by target_wait()/deprecated_target_wait_hook(). This
385 information is returned by get_last_target_status(). */
395 follow_fork_mode_child,
396 follow_fork_mode_parent,
397 NULL
398 };
401 static void
404 {
408 value);
409 }
410 \f
412 /* Handle changes to the inferior list based on the type of fork,
413 which process is being followed, and whether the other process
414 should be detached. On entry inferior_ptid must be the ptid of
415 the fork parent. At return inferior_ptid is the ptid of the
416 followed inferior. */
418 static int
420 {
433 {
434 /* The parent stays blocked inside the vfork syscall until the
435 child execs or exits. If we don't let the child run, then
436 the parent stays blocked. If we're telling the parent to run
437 in the foreground, the user will not be able to ctrl-c to get
438 back the terminal, effectively hanging the debug session. */
443 /* FIXME output string > 80 columns. */
445 }
448 {
449 /* Detach new forked process? */
451 {
452 /* Before detaching from the child, remove all breakpoints
453 from it. If we forked, then this has already been taken
454 care of by infrun.c. If we vforked however, any
455 breakpoint inserted in the parent is visible in the
456 child, even those added while stopped in a vfork
457 catchpoint. This will remove the breakpoints from the
458 parent also, but they'll be reinserted below. */
460 {
461 /* Keep breakpoints list in sync. */
463 }
466 {
467 /* Ensure that we have a process ptid. */
475 }
476 }
477 else
478 {
481 /* Add process to GDB's tables. */
490 scoped_restore_current_pspace_and_thread restore_pspace_thread;
497 /* If this is a vfork child, then the address-space is
498 shared with the parent. */
500 {
504 /* The parent will be frozen until the child is done
505 with the shared region. Keep track of the
506 parent. */
511 }
512 else
513 {
520 /* Let the shared library layer (e.g., solib-svr4) learn
521 about this new process, relocate the cloned exec, pull
522 in shared libraries, and install the solib event
523 breakpoint. If a "cloned-VM" event was propagated
524 better throughout the core, this wouldn't be
525 required. */
527 }
528 }
531 {
536 /* If we detached from the child, then we have to be careful
537 to not insert breakpoints in the parent until the child
538 is done with the shared memory region. However, if we're
539 staying attached to the child, then we can and should
540 insert breakpoints, so that we can debug it. A
541 subsequent child exec or exit is enough to know when does
542 the child stops using the parent's address space. */
545 }
546 }
547 else
548 {
549 /* Follow the child. */
554 {
564 }
566 /* Add the new inferior first, so that the target_detach below
567 doesn't unpush the target. */
579 /* If we're vforking, we want to hold on to the parent until the
580 child exits or execs. At child exec or exit time we can
581 remove the old breakpoints from the parent and detach or
582 resume debugging it. Otherwise, detach the parent now; we'll
583 want to reuse it's program/address spaces, but we can't set
584 them to the child before removing breakpoints from the
585 parent, otherwise, the breakpoints module could decide to
586 remove breakpoints from the wrong process (since they'd be
587 assigned to the same address space). */
590 {
598 }
600 {
602 {
603 /* Ensure that we have a process ptid. */
611 }
614 }
616 /* Note that the detach above makes PARENT_INF dangling. */
618 /* Add the child thread to the appropriate lists, and switch to
619 this new thread, before cloning the program space, and
620 informing the solib layer about this new process. */
626 /* If this is a vfork child, then the address-space is shared
627 with the parent. If we detached from the parent, then we can
628 reuse the parent's program/address spaces. */
630 {
633 }
634 else
635 {
643 /* Let the shared library layer (e.g., solib-svr4) learn
644 about this new process, relocate the cloned exec, pull in
645 shared libraries, and install the solib event breakpoint.
646 If a "cloned-VM" event was propagated better throughout
647 the core, this wouldn't be required. */
649 }
650 }
653 }
655 /* Tell the target to follow the fork we're stopped at. Returns true
656 if the inferior should be resumed; false, if the target for some
657 reason decided it's best not to resume. */
659 static int
661 {
666 /* Copy user stepping state to the new inferior thread. FIXME: the
667 followed fork child thread should have a copy of most of the
668 parent thread structure's run control related fields, not just these.
669 Initialized to avoid "may be used uninitialized" warnings from gcc. */
678 {
679 ptid_t wait_ptid;
682 /* Get the last target status returned by target_wait(). */
685 /* If not stopped at a fork event, then there's nothing else to
686 do. */
691 /* Check if we switched over from WAIT_PTID, since the event was
692 reported. */
695 {
696 /* We did. Switch back to WAIT_PTID thread, to tell the
697 target to follow it (in either direction). We'll
698 afterwards refuse to resume, and inform the user what
699 happened. */
700 thread_info *wait_thread
704 }
705 }
709 /* If there were any forks/vforks that were caught and are now to be
710 followed, then do so now. */
712 {
715 {
718 /* If the user did a next/step, etc, over a fork call,
719 preserve the stepping state in the fork child. */
721 {
722 step_resume_breakpoint = clone_momentary_breakpoint
727 exception_resume_breakpoint
731 /* For now, delete the parent's sr breakpoint, otherwise,
732 parent/child sr breakpoints are considered duplicates,
733 and the child version will not be installed. Remove
734 this when the breakpoints module becomes aware of
735 inferiors and address spaces. */
742 }
747 /* Set up inferior(s) as specified by the caller, and tell the
748 target to do whatever is necessary to follow either parent
749 or child. */
751 {
752 /* Target refused to follow, or there's some other reason
753 we shouldn't resume. */
755 }
756 else
757 {
758 /* This pending follow fork event is now handled, one way
759 or another. The previous selected thread may be gone
760 from the lists by now, but if it is still around, need
761 to clear the pending follow request. */
766 /* This makes sure we don't try to apply the "Switched
767 over from WAIT_PID" logic above. */
770 /* If we followed the child, switch to it... */
772 {
776 /* ... and preserve the stepping state, in case the
777 user was stepping over the fork call. */
779 {
789 }
790 else
791 {
792 /* If we get here, it was because we're trying to
793 resume from a fork catchpoint, but, the user
794 has switched threads away from the thread that
795 forked. In that case, the resume command
796 issued is most likely not applicable to the
797 child, so just warn, and refuse to resume. */
800 }
802 /* Reset breakpoints in the child as appropriate. */
804 }
805 }
806 }
809 /* Nothing to follow. */
816 }
819 }
821 static void
823 {
826 /* Was there a step_resume breakpoint? (There was if the user
827 did a "next" at the fork() call.) If so, explicitly reset its
828 thread number. Cloned step_resume breakpoints are disabled on
829 creation, so enable it here now that it is associated with the
830 correct thread.
832 step_resumes are a form of bp that are made to be per-thread.
833 Since we created the step_resume bp when the parent process
834 was being debugged, and now are switching to the child process,
835 from the breakpoint package's viewpoint, that's a switch of
836 "threads". We must update the bp's notion of which thread
837 it is for, or it'll be ignored when it triggers. */
840 {
843 }
845 /* Treat exception_resume breakpoints like step_resume breakpoints. */
847 {
850 }
852 /* Reinsert all breakpoints in the child. The user may have set
853 breakpoints after catching the fork, in which case those
854 were never set in the child, but only in the parent. This makes
855 sure the inserted breakpoints match the breakpoint list. */
859 }
861 /* The child has exited or execed: resume threads of the parent the
862 user wanted to be executing. */
864 static int
867 {
875 {
884 }
887 }
889 /* Save/restore inferior_ptid, current program space and current
890 inferior. Only use this if the current context points at an exited
891 inferior (and therefore there's no current thread to save). */
892 class scoped_restore_exited_inferior
893 {
897 {}
901 scoped_restore_current_program_space m_pspace;
902 scoped_restore_current_inferior m_inferior;
903 };
905 /* Called whenever we notice an exec or exit event, to handle
906 detaching or resuming a vfork parent. */
908 static void
910 {
914 {
917 /* This exec or exit marks the end of the shared memory region
918 between the parent and the child. Break the bonds. */
923 /* If the user wanted to detach from the parent, now is the
924 time. */
926 {
931 /* follow-fork child, detach-on-fork on. */
936 maybe_restore_inferior;
938 maybe_restore_thread;
940 /* If we're handling a child exit, then inferior_ptid points
941 at the inferior's pid, not to a thread. */
944 else
947 /* We're letting loose of the parent. */
951 /* We're about to detach from the parent, which implicitly
952 removes breakpoints from its address space. There's a
953 catch here: we want to reuse the spaces for the child,
954 but, parent/child are still sharing the pspace at this
955 point, although the exec in reality makes the kernel give
956 the child a fresh set of new pages. The problem here is
957 that the breakpoints module being unaware of this, would
958 likely chose the child process to write to the parent
959 address space. Swapping the child temporarily away from
960 the spaces has the desired effect. Yes, this is "sort
961 of" a hack. */
969 {
976 {
980 }
981 else
982 {
986 }
987 }
991 /* Put it back. */
994 }
996 {
997 /* We're staying attached to the parent, so, really give the
998 child a new address space. */
1005 }
1006 else
1007 {
1010 /* If this is a vfork child exiting, then the pspace and
1011 aspaces were shared with the parent. Since we're
1012 reporting the process exit, we'll be mourning all that is
1013 found in the address space, and switching to null_ptid,
1014 preparing to start a new inferior. But, since we don't
1015 want to clobber the parent's address/program spaces, we
1016 go ahead and create a new one for this exiting
1017 inferior. */
1019 /* Switch to null_ptid while running clone_program_space, so
1020 that clone_program_space doesn't want to read the
1021 selected frame of a dead process. */
1022 scoped_restore restore_ptid
1025 /* This inferior is dead, so avoid giving the breakpoints
1026 module the option to write through to it (cloning a
1027 program space resets breakpoints). */
1039 }
1044 {
1045 /* If the user wanted the parent to be running, let it go
1046 free now. */
1047 scoped_restore_current_thread restore_thread;
1052 resume_parent);
1055 }
1056 }
1057 }
1059 /* Enum strings for "set|show follow-exec-mode". */
1064 {
1065 follow_exec_mode_new,
1066 follow_exec_mode_same,
1067 NULL,
1068 };
1071 static void
1074 {
1076 }
1078 /* EXEC_FILE_TARGET is assumed to be non-NULL. */
1080 static void
1082 {
1085 ptid_t process_ptid;
1087 /* Switch terminal for any messages produced e.g. by
1088 breakpoint_re_set. */
1091 /* This is an exec event that we actually wish to pay attention to.
1092 Refresh our symbol table to the newly exec'd program, remove any
1093 momentary bp's, etc.
1095 If there are breakpoints, they aren't really inserted now,
1096 since the exec() transformed our inferior into a fresh set
1097 of instructions.
1099 We want to preserve symbolic breakpoints on the list, since
1100 we have hopes that they can be reset after the new a.out's
1101 symbol table is read.
1103 However, any "raw" breakpoints must be removed from the list
1104 (e.g., the solib bp's), since their address is probably invalid
1105 now.
1107 And, we DON'T want to call delete_breakpoints() here, since
1108 that may write the bp's "shadow contents" (the instruction
1109 value that was overwritten witha TRAP instruction). Since
1110 we now have a new a.out, those shadow contents aren't valid. */
1114 /* The target reports the exec event to the main thread, even if
1115 some other thread does the exec, and even if the main thread was
1116 stopped or already gone. We may still have non-leader threads of
1117 the process on our list. E.g., on targets that don't have thread
1118 exit events (like remote); or on native Linux in non-stop mode if
1119 there were only two threads in the inferior and the non-leader
1120 one is the one that execs (and nothing forces an update of the
1121 thread list up to here). When debugging remotely, it's best to
1122 avoid extra traffic, when possible, so avoid syncing the thread
1123 list with the target, and instead go ahead and delete all threads
1124 of the process but one that reported the event. Note this must
1125 be done before calling update_breakpoints_after_exec, as
1126 otherwise clearing the threads' resources would reference stale
1127 thread breakpoints -- it may have been one of these threads that
1128 stepped across the exec. We could just clear their stepping
1129 states, but as long as we're iterating, might as well delete
1130 them. Deleting them now rather than at the next user-visible
1131 stop provides a nicer sequence of events for user and MI
1132 notifications. */
1137 /* We also need to clear any left over stale state for the
1138 leader/event thread. E.g., if there was any step-resume
1139 breakpoint or similar, it's gone now. We cannot truly
1140 step-to-next statement through an exec(). */
1148 /* The user may have had the main thread held stopped in the
1149 previous image (e.g., schedlock on, or non-stop). Release
1150 it now. */
1155 /* What is this a.out's name? */
1159 exec_file_target);
1161 /* We've followed the inferior through an exec. Therefore, the
1162 inferior has essentially been killed & reborn. */
1169 /* If we were unable to map the executable target pathname onto a host
1170 pathname, tell the user that. Otherwise GDB's subsequent behavior
1171 is confusing. Maybe it would even be better to stop at this point
1172 so that the user can specify a file manually before continuing. */
1176 exec_file_target);
1178 /* Reset the shared library package. This ensures that we get a
1179 shlib event when the child reaches "_start", at which point the
1180 dld will have had a chance to initialize the child. */
1181 /* Also, loading a symbol file below may trigger symbol lookups, and
1182 we don't want those to be satisfied by the libraries of the
1183 previous incarnation of this process. */
1187 {
1188 /* The user wants to keep the old inferior and program spaces
1189 around. Create a new fresh one, and switch to it. */
1191 /* Do exit processing for the original inferior before setting the new
1192 inferior's pid. Having two inferiors with the same pid would confuse
1193 find_inferior_p(t)id. Transfer the terminal state and info from the
1194 old to the new inferior. */
1205 }
1206 else
1207 {
1208 /* The old description may no longer be fit for the new image.
1209 E.g, a 64-bit process exec'ed a 32-bit process. Clear the
1210 old description; we'll read a new one below. No need to do
1211 this on "follow-exec-mode new", as the old inferior stays
1212 around (its description is later cleared/refetched on
1213 restart). */
1215 }
1219 /* Attempt to open the exec file. SYMFILE_DEFER_BP_RESET is used
1220 because the proper displacement for a PIE (Position Independent
1221 Executable) main symbol file will only be computed by
1222 solib_create_inferior_hook below. breakpoint_re_set would fail
1223 to insert the breakpoints with the zero displacement. */
1226 /* If the target can specify a description, read it. Must do this
1227 after flipping to the new executable (because the target supplied
1228 description must be compatible with the executable's
1229 architecture, and the old executable may e.g., be 32-bit, while
1230 the new one 64-bit), and before anything involving memory or
1231 registers. */
1240 /* Reinsert all breakpoints. (Those which were symbolic have
1241 been reset to the proper address in the new a.out, thanks
1242 to symbol_file_command...). */
1245 /* The next resume of this inferior should bring it to the shlib
1246 startup breakpoints. (If the user had also set bp's on
1247 "main" from the old (parent) process, then they'll auto-
1248 matically get reset there in the new process.). */
1249 }
1251 /* The queue of threads that need to do a step-over operation to get
1252 past e.g., a breakpoint. What technique is used to step over the
1253 breakpoint/watchpoint does not matter -- all threads end up in the
1254 same queue, to maintain rough temporal order of execution, in order
1255 to avoid starvation, otherwise, we could e.g., find ourselves
1256 constantly stepping the same couple threads past their breakpoints
1257 over and over, if the single-step finish fast enough. */
1260 /* Bit flags indicating what the thread needs to step over. */
1262 enum step_over_what_flag
1263 {
1264 /* Step over a breakpoint. */
1267 /* Step past a non-continuable watchpoint, in order to let the
1268 instruction execute so we can evaluate the watchpoint
1269 expression. */
1271 };
1274 /* Info about an instruction that is being stepped over. */
1276 struct step_over_info
1277 {
1278 /* If we're stepping past a breakpoint, this is the address space
1279 and address of the instruction the breakpoint is set at. We'll
1280 skip inserting all breakpoints here. Valid iff ASPACE is
1281 non-NULL. */
1283 CORE_ADDR address;
1285 /* The instruction being stepped over triggers a nonsteppable
1286 watchpoint. If true, we'll skip inserting watchpoints. */
1289 /* The thread's global number. */
1291 };
1293 /* The step-over info of the location that is being stepped over.
1295 Note that with async/breakpoint always-inserted mode, a user might
1296 set a new breakpoint/watchpoint/etc. exactly while a breakpoint is
1297 being stepped over. As setting a new breakpoint inserts all
1298 breakpoints, we need to make sure the breakpoint being stepped over
1299 isn't inserted then. We do that by only clearing the step-over
1300 info when the step-over is actually finished (or aborted).
1302 Presently GDB can only step over one breakpoint at any given time.
1303 Given threads that can't run code in the same address space as the
1304 breakpoint's can't really miss the breakpoint, GDB could be taught
1305 to step-over at most one breakpoint per address space (so this info
1306 could move to the address space object if/when GDB is extended).
1307 The set of breakpoints being stepped over will normally be much
1308 smaller than the set of all breakpoints, so a flag in the
1309 breakpoint location structure would be wasteful. A separate list
1310 also saves complexity and run-time, as otherwise we'd have to go
1311 through all breakpoint locations clearing their flag whenever we
1312 start a new sequence. Similar considerations weigh against storing
1313 this info in the thread object. Plus, not all step overs actually
1314 have breakpoint locations -- e.g., stepping past a single-step
1315 breakpoint, or stepping to complete a non-continuable
1316 watchpoint. */
1319 /* Record the address of the breakpoint/instruction we're currently
1320 stepping over.
1321 N.B. We record the aspace and address now, instead of say just the thread,
1322 because when we need the info later the thread may be running. */
1324 static void
1328 {
1333 }
1335 /* Called when we're not longer stepping over a breakpoint / an
1336 instruction, so all breakpoints are free to be (re)inserted. */
1338 static void
1340 {
1348 }
1350 /* See infrun.h. */
1352 int
1354 CORE_ADDR address)
1355 {
1360 }
1362 /* See infrun.h. */
1364 int
1366 {
1369 }
1371 /* See infrun.h. */
1373 int
1375 {
1377 }
1379 /* Returns true if step-over info is valid. */
1381 static int
1383 {
1386 }
1388 \f
1389 /* Displaced stepping. */
1391 /* In non-stop debugging mode, we must take special care to manage
1392 breakpoints properly; in particular, the traditional strategy for
1393 stepping a thread past a breakpoint it has hit is unsuitable.
1394 'Displaced stepping' is a tactic for stepping one thread past a
1395 breakpoint it has hit while ensuring that other threads running
1396 concurrently will hit the breakpoint as they should.
1398 The traditional way to step a thread T off a breakpoint in a
1399 multi-threaded program in all-stop mode is as follows:
1401 a0) Initially, all threads are stopped, and breakpoints are not
1402 inserted.
1403 a1) We single-step T, leaving breakpoints uninserted.
1404 a2) We insert breakpoints, and resume all threads.
1406 In non-stop debugging, however, this strategy is unsuitable: we
1407 don't want to have to stop all threads in the system in order to
1408 continue or step T past a breakpoint. Instead, we use displaced
1409 stepping:
1411 n0) Initially, T is stopped, other threads are running, and
1412 breakpoints are inserted.
1413 n1) We copy the instruction "under" the breakpoint to a separate
1414 location, outside the main code stream, making any adjustments
1415 to the instruction, register, and memory state as directed by
1416 T's architecture.
1417 n2) We single-step T over the instruction at its new location.
1418 n3) We adjust the resulting register and memory state as directed
1419 by T's architecture. This includes resetting T's PC to point
1420 back into the main instruction stream.
1421 n4) We resume T.
1423 This approach depends on the following gdbarch methods:
1425 - gdbarch_max_insn_length and gdbarch_displaced_step_location
1426 indicate where to copy the instruction, and how much space must
1427 be reserved there. We use these in step n1.
1429 - gdbarch_displaced_step_copy_insn copies a instruction to a new
1430 address, and makes any necessary adjustments to the instruction,
1431 register contents, and memory. We use this in step n1.
1433 - gdbarch_displaced_step_fixup adjusts registers and memory after
1434 we have successfuly single-stepped the instruction, to yield the
1435 same effect the instruction would have had if we had executed it
1436 at its original address. We use this in step n3.
1438 The gdbarch_displaced_step_copy_insn and
1439 gdbarch_displaced_step_fixup functions must be written so that
1440 copying an instruction with gdbarch_displaced_step_copy_insn,
1441 single-stepping across the copied instruction, and then applying
1442 gdbarch_displaced_insn_fixup should have the same effects on the
1443 thread's memory and registers as stepping the instruction in place
1444 would have. Exactly which responsibilities fall to the copy and
1445 which fall to the fixup is up to the author of those functions.
1447 See the comments in gdbarch.sh for details.
1449 Note that displaced stepping and software single-step cannot
1450 currently be used in combination, although with some care I think
1451 they could be made to. Software single-step works by placing
1452 breakpoints on all possible subsequent instructions; if the
1453 displaced instruction is a PC-relative jump, those breakpoints
1454 could fall in very strange places --- on pages that aren't
1455 executable, or at addresses that are not proper instruction
1456 boundaries. (We do generally let other threads run while we wait
1457 to hit the software single-step breakpoint, and they might
1458 encounter such a corrupted instruction.) One way to work around
1459 this would be to have gdbarch_displaced_step_copy_insn fully
1460 simulate the effect of PC-relative instructions (and return NULL)
1461 on architectures that use software single-stepping.
1463 In non-stop mode, we can have independent and simultaneous step
1464 requests, so more than one thread may need to simultaneously step
1465 over a breakpoint. The current implementation assumes there is
1466 only one scratch space per process. In this case, we have to
1467 serialize access to the scratch space. If thread A wants to step
1468 over a breakpoint, but we are currently waiting for some other
1469 thread to complete a displaced step, we leave thread A stopped and
1470 place it in the displaced_step_request_queue. Whenever a displaced
1471 step finishes, we pick the next thread in the queue and start a new
1472 displaced step operation on it. See displaced_step_prepare and
1473 displaced_step_fixup for details. */
1475 /* Default destructor for displaced_step_closure. */
1479 /* Get the displaced stepping state of process PID. */
1483 {
1485 }
1487 /* Returns true if any inferior has a thread doing a displaced
1488 step. */
1490 static bool
1492 {
1494 {
1497 }
1500 }
1502 /* Return true if thread represented by PTID is doing a displaced
1503 step. */
1505 static int
1507 {
1511 }
1513 /* Return true if process PID has a thread doing a displaced step. */
1515 static int
1517 {
1519 }
1521 /* If inferior is in displaced stepping, and ADDR equals to starting address
1522 of copy area, return corresponding displaced_step_closure. Otherwise,
1523 return NULL. */
1527 {
1528 displaced_step_inferior_state *displaced
1531 /* If checking the mode of displaced instruction in copy area. */
1537 }
1539 static void
1541 {
1543 }
1545 /* If ON, and the architecture supports it, GDB will use displaced
1546 stepping to step over breakpoints. If OFF, or if the architecture
1547 doesn't support it, GDB will instead use the traditional
1548 hold-and-step approach. If AUTO (which is the default), GDB will
1549 decide which technique to use to step over breakpoints depending on
1550 which of all-stop or non-stop mode is active --- displaced stepping
1551 in non-stop mode; hold-and-step in all-stop mode. */
1555 static void
1559 {
1565 else
1569 }
1571 /* Return non-zero if displaced stepping can/should be used to step
1572 over breakpoints of thread TP. */
1574 static int
1576 {
1579 displaced_step_inferior_state *displaced_state
1588 }
1590 /* Clean out any stray displaced stepping state. */
1591 static void
1593 {
1594 /* Indicate that there is no cleanup pending. */
1599 }
1601 /* A cleanup that wraps displaced_step_clear. */
1602 using displaced_step_clear_cleanup
1605 /* Dump LEN bytes at BUF in hex to FILE, followed by a newline. */
1606 void
1610 {
1616 }
1618 /* Prepare to single-step, using displaced stepping.
1620 Note that we cannot use displaced stepping when we have a signal to
1621 deliver. If we have a signal to deliver and an instruction to step
1622 over, then after the step, there will be no indication from the
1623 target whether the thread entered a signal handler or ignored the
1624 signal and stepped over the instruction successfully --- both cases
1625 result in a simple SIGTRAP. In the first case we mustn't do a
1626 fixup, and in the second case we must --- but we can't tell which.
1627 Comments in the code for 'random signals' in handle_inferior_event
1628 explain how we handle this case instead.
1630 Returns 1 if preparing was successful -- this thread is going to be
1631 stepped now; 0 if displaced stepping this thread got queued; or -1
1632 if this instruction can't be displaced stepped. */
1634 static int
1636 {
1641 ULONGEST len;
1645 /* We should never reach this function if the architecture does not
1646 support displaced stepping. */
1649 /* Nor if the thread isn't meant to step over a breakpoint. */
1652 /* Disable range stepping while executing in the scratch pad. We
1653 want a single-step even if executing the displaced instruction in
1654 the scratch buffer lands within the stepping range (e.g., a
1655 jump/branch). */
1658 /* We have to displaced step one thread at a time, as we only have
1659 access to a single scratch space per inferior. */
1661 displaced_step_inferior_state *displaced
1665 {
1666 /* Already waiting for a displaced step to finish. Defer this
1667 request and place in queue. */
1676 }
1677 else
1678 {
1683 }
1687 scoped_restore_current_thread restore_thread;
1697 {
1698 /* There's a breakpoint set in the scratch pad location range
1699 (which is usually around the entry point). We'd either
1700 install it before resuming, which would overwrite/corrupt the
1701 scratch pad, or if it was already inserted, this displaced
1702 step would overwrite it. The latter is OK in the sense that
1703 we already assume that no thread is going to execute the code
1704 in the scratch pad range (after initial startup) anyway, but
1705 the former is unacceptable. Simply punt and fallback to
1706 stepping over this breakpoint in-line. */
1708 {
1710 "displaced: breakpoint set in scratch pad. "
1712 }
1715 }
1717 /* Save the original contents of the copy area. */
1726 {
1731 len);
1732 };
1737 {
1738 /* The architecture doesn't know how or want to displaced step
1739 this instruction or instruction sequence. Fallback to
1740 stepping over the breakpoint in-line. */
1742 }
1744 /* Save the information we need to fix things up if the step
1745 succeeds. */
1752 {
1755 /* Resume execution at the copy. */
1759 }
1766 }
1768 /* Wrapper for displaced_step_prepare_throw that disabled further
1769 attempts at displaced stepping if we get a memory error. */
1771 static int
1773 {
1776 try
1777 {
1779 }
1781 {
1789 {
1793 }
1795 /* Be verbose if "set displaced-stepping" is "on", silent if
1796 "auto". */
1798 {
1801 }
1803 /* Disable further displaced stepping attempts. */
1804 displaced_state
1807 }
1810 }
1812 static void
1815 {
1820 }
1822 /* Restore the contents of the copy area for thread PTID. */
1824 static void
1826 ptid_t ptid)
1827 {
1837 }
1839 /* If we displaced stepped an instruction successfully, adjust
1840 registers and memory to yield the same effect the instruction would
1841 have had if we had executed it at its original address, and return
1842 1. If the instruction didn't complete, relocate the PC and return
1843 -1. If the thread wasn't displaced stepping, return 0. */
1845 static int
1847 {
1852 /* Was this event for the thread we displaced? */
1860 /* Fixup may need to read memory/registers. Switch to the thread
1861 that we're fixing up. Also, target_stopped_by_watchpoint checks
1862 the current thread. */
1865 /* Did the instruction complete successfully? */
1870 {
1871 /* Fix up the resulting state. */
1878 }
1879 else
1880 {
1881 /* Since the instruction didn't complete, all we can do is
1882 relocate the PC. */
1889 }
1892 }
1894 /* Data to be passed around while handling an event. This data is
1895 discarded between events. */
1896 struct execution_control_state
1897 {
1898 ptid_t ptid;
1899 /* The thread that got the event, if this was a thread event; NULL
1900 otherwise. */
1905 CORE_ADDR stop_func_start;
1906 CORE_ADDR stop_func_end;
1910 /* True if the event thread hit the single-step breakpoint of
1911 another thread. Thus the event doesn't cause a stop, the thread
1912 needs to be single-stepped past the single-step breakpoint before
1913 we can switch back to the original stepping thread. */
1915 };
1917 /* Clear ECS and set it to point at TP. */
1919 static void
1921 {
1925 }
1932 /* Are there any pending step-over requests? If so, run all we can
1933 now and return true. Otherwise, return false. */
1935 static int
1937 {
1940 /* Don't start a new step-over if we already have an in-line
1941 step-over operation ongoing. */
1946 {
1949 step_over_what step_what;
1956 /* If this inferior already has a displaced step in process,
1957 don't start a new one. */
1966 /* We currently stop all threads of all processes to step-over
1967 in-line. If we need to start a new in-line step-over, let
1968 any pending displaced steps finish first. */
1975 {
1979 }
1984 {
1986 "[%s] has inconsistent state: "
1992 }
1999 /* keep_going_pass_signal skips the step-over if the breakpoint
2000 is no longer inserted. In all-stop, we want to keep looking
2001 for a thread that needs a step-over instead of resuming TP,
2002 because we wouldn't be able to resume anything else until the
2003 target stops again. In non-stop, the resume always resumes
2004 only TP, so it's OK to let the thread resume freely. */
2017 /* If we started a new in-line step-over, we're done. */
2019 {
2022 }
2025 {
2026 /* On all-stop, shouldn't have resumed unless we needed a
2027 step over. */
2031 /* With remote targets (at least), in all-stop, we can't
2032 issue any further remote commands until the program stops
2033 again. */
2035 }
2037 /* Either the thread no longer needed a step-over, or a new
2038 displaced stepping sequence started. Even in the latter
2039 case, continue looking. Maybe we can also start another
2040 displaced step on a thread of other process. */
2041 }
2044 }
2046 /* Update global variables holding ptids to hold NEW_PTID if they were
2047 holding OLD_PTID. */
2048 static void
2050 {
2053 }
2055 \f
2062 schedlock_off,
2063 schedlock_on,
2064 schedlock_step,
2065 schedlock_replay,
2066 NULL
2067 };
2069 static void
2072 {
2076 value);
2077 }
2079 static void
2081 {
2083 {
2086 }
2087 }
2089 /* True if execution commands resume all threads of all processes by
2090 default; otherwise, resume only threads of the current inferior
2091 process. */
2094 /* Try to setup for software single stepping over the specified location.
2095 Return 1 if target_resume() should use hardware single step.
2097 GDBARCH the current gdbarch.
2098 PC the location to step over. */
2100 static int
2102 {
2110 }
2112 /* See infrun.h. */
2114 ptid_t
2116 {
2117 ptid_t resume_ptid;
2120 {
2121 /* With non-stop mode on, threads are always handled
2122 individually. */
2124 }
2127 {
2128 /* User-settable 'scheduler' mode requires solo thread
2129 resume. */
2131 }
2134 {
2135 /* User-settable 'scheduler' mode requires solo thread resume in replay
2136 mode. */
2138 }
2140 {
2141 /* Resume all threads of the current process (and none of other
2142 processes). */
2144 }
2145 else
2146 {
2147 /* Resume all threads of all processes. */
2149 }
2152 }
2154 /* Return a ptid representing the set of threads that we will resume,
2155 in the perspective of the target, assuming run control handling
2156 does not require leaving some threads stopped (e.g., stepping past
2157 breakpoint). USER_STEP indicates whether we're about to start the
2158 target for a stepping command. */
2160 static ptid_t
2162 {
2163 /* In non-stop, we always control threads individually. Note that
2164 the target may always work in non-stop mode even with "set
2165 non-stop off", in which case user_visible_resume_ptid could
2166 return a wildcard ptid. */
2169 else
2171 }
2173 /* Wrapper for target_resume, that handles infrun-specific
2174 bookkeeping. */
2176 static void
2178 {
2183 /* Install inferior's terminal modes. */
2186 /* Avoid confusing the next resume, if the next stop/resume
2187 happens to apply to another thread. */
2190 /* Advise target which signals may be handled silently.
2192 If we have removed breakpoints because we are stepping over one
2193 in-line (in any thread), we need to receive all signals to avoid
2194 accidentally skipping a breakpoint during execution of a signal
2195 handler.
2197 Likewise if we're displaced stepping, otherwise a trap for a
2198 breakpoint in a signal handler might be confused with the
2199 displaced step finishing. We don't make the displaced_step_fixup
2200 step distinguish the cases instead, because:
2202 - a backtrace while stopped in the signal handler would show the
2203 scratch pad as frame older than the signal handler, instead of
2204 the real mainline code.
2206 - when the thread is later resumed, the signal handler would
2207 return to the scratch pad area, which would no longer be
2208 valid. */
2212 else
2218 }
2220 /* Resume the inferior. SIG is the signal to give the inferior
2221 (GDB_SIGNAL_0 for none). Note: don't call this directly; instead
2222 call 'resume', which handles exceptions. */
2224 static void
2226 {
2232 ptid_t resume_ptid;
2233 /* This represents the user's step vs continue request. When
2234 deciding whether "set scheduler-locking step" applies, it's the
2235 user's intention that counts. */
2237 /* This represents what we'll actually request the target to do.
2238 This can decay from a step to a continue, if e.g., we need to
2239 implement single-stepping with breakpoints (software
2240 single-step). */
2247 {
2249 {
2254 "infrun: resume: thread %s has pending wait "
2259 }
2263 /* FIXME: What should we do if we are supposed to resume this
2264 thread with a signal? Maybe we should maintain a queue of
2265 pending signals to deliver. */
2267 {
2271 }
2276 {
2278 /* Tell the event loop we have an event to process. */
2280 }
2282 }
2286 /* Depends on stepped_breakpoint. */
2290 {
2291 /* Don't try to single-step a vfork parent that is waiting for
2292 the child to get out of the shared memory region (by exec'ing
2293 or exiting). This is particularly important on software
2294 single-step archs, as the child process would trip on the
2295 software single step breakpoint inserted for the parent
2296 process. Since the parent will not actually execute any
2297 instruction until the child is out of the shared region (such
2298 are vfork's semantics), it is safe to simply continue it.
2299 Eventually, we'll see a TARGET_WAITKIND_VFORK_DONE event for
2300 the parent, and tell it to `keep_going', which automatically
2301 re-sets it stepping. */
2306 }
2310 "infrun: resume (step=%d, signal=%s), "
2317 /* Normally, by the time we reach `resume', the breakpoints are either
2318 removed or inserted, as appropriate. The exception is if we're sitting
2319 at a permanent breakpoint; we need to step over it, but permanent
2320 breakpoints can't be removed. So we have to test for it here. */
2322 {
2324 {
2325 /* We have a signal to pass to the inferior. The resume
2326 may, or may not take us to the signal handler. If this
2327 is a step, we'll need to stop in the signal handler, if
2328 there's one, (if the target supports stepping into
2329 handlers), or in the next mainline instruction, if
2330 there's no handler. If this is a continue, we need to be
2331 sure to run the handler with all breakpoints inserted.
2332 In all cases, set a breakpoint at the current address
2333 (where the handler returns to), and once that breakpoint
2334 is hit, resume skipping the permanent breakpoint. If
2335 that breakpoint isn't hit, then we've stepped into the
2336 signal handler (or hit some other event). We'll delete
2337 the step-resume breakpoint then. */
2341 "infrun: resume: skipping permanent breakpoint, "
2348 {
2349 /* Set a "high-priority" step-resume, as we don't want
2350 user breakpoints at PC to trigger (again) when this
2351 hits. */
2356 }
2359 }
2360 else
2361 {
2362 /* There's no signal to pass, we can go ahead and skip the
2363 permanent breakpoint manually. */
2368 /* Update pc to reflect the new address from which we will
2369 execute instructions. */
2373 {
2374 /* We've already advanced the PC, so the stepping part
2375 is done. Now we need to arrange for a trap to be
2376 reported to handle_inferior_event. Set a breakpoint
2377 at the current PC, and run to it. Don't update
2378 prev_pc, because if we end in
2379 switch_back_to_stepped_thread, we want the "expected
2380 thread advanced also" branch to be taken. IOW, we
2381 don't want this thread to step further from PC
2382 (overstep). */
2391 }
2392 }
2393 }
2395 /* If we have a breakpoint to step over, make sure to do a single
2396 step only. Same if we have software watchpoints. */
2400 /* If enabled, step over breakpoints by executing a copy of the
2401 instruction at a different address.
2403 We can't use displaced stepping when we have a signal to deliver;
2404 the comments for displaced_step_prepare explain why. The
2405 comments in the handle_inferior event for dealing with 'random
2406 signals' explain what we do instead.
2408 We can't use displaced stepping when we are waiting for vfork_done
2409 event, displaced stepping breaks the vfork child similarly as single
2410 step software breakpoint. */
2416 {
2420 {
2427 }
2429 {
2430 /* Fallback to stepping over the breakpoint in-line. */
2441 }
2443 {
2446 /* Update pc to reflect the new address from which we will
2447 execute instructions due to displaced stepping. */
2453 }
2454 }
2456 /* Do we need to do it the hard way, w/temp breakpoints? */
2460 /* Currently, our software single-step implementation leads to different
2461 results than hardware single-stepping in one situation: when stepping
2462 into delivering a signal which has an associated signal handler,
2463 hardware single-step will stop at the first instruction of the handler,
2464 while software single-step will simply skip execution of the handler.
2466 For now, this difference in behavior is accepted since there is no
2467 easy way to actually implement single-stepping into a signal handler
2468 without kernel support.
2470 However, there is one scenario where this difference leads to follow-on
2471 problems: if we're stepping off a breakpoint by removing all breakpoints
2472 and then single-stepping. In this case, the software single-step
2473 behavior means that even if there is a *breakpoint* in the signal
2474 handler, GDB still would not stop.
2476 Fortunately, we can at least fix this particular issue. We detect
2477 here the case where we are about to deliver a signal while software
2478 single-stepping with breakpoints removed. In this situation, we
2479 revert the decisions to remove all breakpoints and insert single-
2480 step breakpoints, and instead we install a step-resume breakpoint
2481 at the current address, deliver the signal without stepping, and
2482 once we arrive back at the step-resume breakpoint, actually step
2483 over the breakpoint we originally wanted to step over. */
2487 {
2488 /* If we have nested signals or a pending signal is delivered
2489 immediately after a handler returns, might might already have
2490 a step-resume breakpoint set on the earlier handler. We cannot
2491 set another step-resume breakpoint; just continue on until the
2492 original breakpoint is hit. */
2494 {
2497 }
2505 }
2507 /* If STEP is set, it's a request to use hardware stepping
2508 facilities. But in that case, we should never
2509 use singlestep breakpoint. */
2512 /* Decide the set of threads to ask the target to resume. */
2514 {
2515 /* We're allowing a thread to run past a breakpoint it has
2516 hit, either by single-stepping the thread with the breakpoint
2517 removed, or by displaced stepping, with the breakpoint inserted.
2518 In the former case, we need to single-step only this thread,
2519 and keep others stopped, as they can miss this breakpoint if
2520 allowed to run. That's not really a problem for displaced
2521 stepping, but, we still keep other threads stopped, in case
2522 another thread is also stopped for a breakpoint waiting for
2523 its turn in the displaced stepping queue. */
2525 }
2526 else
2531 {
2532 /* There are two cases where we currently need to step a
2533 breakpoint instruction when we have a signal to deliver:
2535 - See handle_signal_stop where we handle random signals that
2536 could take out us out of the stepping range. Normally, in
2537 that case we end up continuing (instead of stepping) over the
2538 signal handler with a breakpoint at PC, but there are cases
2539 where we should _always_ single-step, even if we have a
2540 step-resume breakpoint, like when a software watchpoint is
2541 set. Assuming single-stepping and delivering a signal at the
2542 same time would takes us to the signal handler, then we could
2543 have removed the breakpoint at PC to step over it. However,
2544 some hardware step targets (like e.g., Mac OS) can't step
2545 into signal handlers, and for those, we need to leave the
2546 breakpoint at PC inserted, as otherwise if the handler
2547 recurses and executes PC again, it'll miss the breakpoint.
2548 So we leave the breakpoint inserted anyway, but we need to
2549 record that we tried to step a breakpoint instruction, so
2550 that adjust_pc_after_break doesn't end up confused.
2552 - In non-stop if we insert a breakpoint (e.g., a step-resume)
2553 in one thread after another thread that was stepping had been
2554 momentarily paused for a step-over. When we re-resume the
2555 stepping thread, it may be resumed from that address with a
2556 breakpoint that hasn't trapped yet. Seen with
2557 gdb.threads/non-stop-fair-events.exp, on targets that don't
2558 do displaced stepping. */
2567 /* Most targets can step a breakpoint instruction, thus
2568 executing it normally. But if this one cannot, just
2569 continue and we will hit it anyway. */
2572 }
2578 {
2588 }
2591 {
2592 /* If we're resuming a thread with the PC out of the step
2593 range, then we're doing some nested/finer run control
2594 operation, like stepping the thread out of the dynamic
2595 linker or the displaced stepping scratch pad. We
2596 shouldn't have allowed a range step then. */
2598 }
2602 }
2604 /* Resume the inferior. SIG is the signal to give the inferior
2605 (GDB_SIGNAL_0 for none). This is a wrapper around 'resume_1' that
2606 rolls back state on error. */
2608 static void
2610 {
2611 try
2612 {
2614 }
2616 {
2617 /* If resuming is being aborted for any reason, delete any
2618 single-step breakpoint resume_1 may have created, to avoid
2619 confusing the following resumption, and to avoid leaving
2620 single-step breakpoints perturbing other threads, in case
2621 we're running in non-stop mode. */
2625 }
2626 }
2628 \f
2629 /* Proceeding. */
2631 /* See infrun.h. */
2633 /* Counter that tracks number of user visible stops. This can be used
2634 to tell whether a command has proceeded the inferior past the
2635 current location. This allows e.g., inferior function calls in
2636 breakpoint commands to not interrupt the command list. When the
2637 call finishes successfully, the inferior is standing at the same
2638 breakpoint as if nothing happened (and so we don't call
2639 normal_stop). */
2642 /* See infrun.h. */
2644 ULONGEST
2646 {
2648 }
2650 /* Called when we report a user visible stop. */
2652 static void
2654 {
2655 current_stop_id++;
2656 }
2658 /* Clear out all variables saying what to do when inferior is continued.
2659 First do this, then set the ones you want, then call `proceed'. */
2661 static void
2663 {
2669 /* If we're starting a new sequence, then the previous finished
2670 single-step is no longer relevant. */
2672 {
2674 {
2677 "infrun: clear_proceed_status: pending "
2678 "event of %s was a finished step. "
2684 }
2686 {
2691 "infrun: clear_proceed_status_thread: thread %s "
2692 "has pending wait status %s "
2697 }
2698 }
2700 /* If this signal should not be seen by program, give it zero.
2701 Used for debugging signals. */
2724 /* Discard any remaining commands or status from previous stop. */
2726 }
2728 void
2730 {
2731 /* With scheduler-locking replay, stop replaying other threads if we're
2732 not replaying the user-visible resume ptid.
2734 This is a convenience feature to not require the user to explicitly
2735 stop replaying the other threads. We're assuming that the user's
2736 intent is to resume tracing the recorded process. */
2740 execution_direction))
2744 {
2747 /* In all-stop mode, delete the per-thread status of all threads
2748 we're about to resume, implicitly and explicitly. */
2751 }
2754 {
2758 {
2759 /* If in non-stop mode, only delete the per-thread status of
2760 the current thread. */
2762 }
2766 }
2769 }
2771 /* Returns true if TP is still stopped at a breakpoint that needs
2772 stepping-over in order to make progress. If the breakpoint is gone
2773 meanwhile, we can skip the whole step-over dance. */
2775 static int
2777 {
2779 {
2788 }
2791 }
2793 /* Check whether thread TP still needs to start a step-over in order
2794 to make progress when resumed. Returns an bitwise or of enum
2795 step_over_what bits, indicating what needs to be stepped over. */
2797 static step_over_what
2799 {
2810 }
2812 /* Returns true if scheduler locking applies. STEP indicates whether
2813 we're about to do a step/next-like command to a thread. */
2815 static int
2817 {
2823 execution_direction)));
2824 }
2826 /* Basic routine for continuing the program in various fashions.
2828 ADDR is the address to resume at, or -1 for resume where stopped.
2829 SIGGNAL is the signal to give it, or GDB_SIGNAL_0 for none,
2830 or GDB_SIGNAL_DEFAULT for act according to how it stopped.
2832 You should call clear_proceed_status before calling proceed. */
2834 void
2836 {
2839 CORE_ADDR pc;
2840 ptid_t resume_ptid;
2845 /* If we're stopped at a fork/vfork, follow the branch set by the
2846 "set follow-fork-mode" command; otherwise, we'll just proceed
2847 resuming the current thread. */
2849 {
2850 /* The target for some reason decided not to resume. */
2855 }
2857 /* We'll update this if & when we switch to a new thread. */
2867 /* Fill in with reasonable starting values. */
2873 {
2877 /* There is a breakpoint at the address we will resume at,
2878 step one instruction before inserting breakpoints so that
2879 we do not stop right away (and report a second hit at this
2880 breakpoint).
2882 Note, we don't do this in reverse, because we won't
2883 actually be executing the breakpoint insn anyway.
2884 We'll be (un-)executing the previous instruction. */
2889 /* We stepped onto an instruction that needs to be stepped
2890 again before re-inserting the breakpoint, do so. */
2892 }
2893 else
2894 {
2896 }
2903 /* If an exception is thrown from this point on, make sure to
2904 propagate GDB's knowledge of the executing state to the
2905 frontend/user running state. */
2908 /* Even if RESUME_PTID is a wildcard, and we end up resuming fewer
2909 threads (e.g., we might need to set threads stepping over
2910 breakpoints first), from the user/frontend's point of view, all
2911 threads in RESUME_PTID are now running. Unless we're calling an
2912 inferior function, as in that case we pretend the inferior
2913 doesn't run at all. */
2925 /* Make sure that output from GDB appears before output from the
2926 inferior. */
2929 /* Since we've marked the inferior running, give it the terminal. A
2930 QUIT/Ctrl-C from here on is forwarded to the target (which can
2931 still detect attempts to unblock a stuck connection with repeated
2932 Ctrl-C from within target_pass_ctrlc). */
2935 /* In a multi-threaded task we may select another thread and
2936 then continue or step.
2938 But if a thread that we're resuming had stopped at a breakpoint,
2939 it will immediately cause another breakpoint stop without any
2940 execution (i.e. it will report a breakpoint hit incorrectly). So
2941 we must step over it first.
2943 Look for threads other than the current (TP) that reported a
2944 breakpoint hit and haven't been resumed yet since. */
2946 /* If scheduler locking applies, we can avoid iterating over all
2947 threads. */
2949 {
2951 {
2952 /* Ignore the current thread here. It's handled
2953 afterwards. */
2968 }
2969 }
2971 /* Enqueue the current thread last, so that we move all other
2972 threads over their breakpoints first. */
2976 /* If the thread isn't started, we'll still need to set its prev_pc,
2977 so that switch_back_to_stepped_thread knows the thread hasn't
2978 advanced. Must do this before resuming any thread, as in
2979 all-stop/remote, once we resume we can't send any other packet
2980 until the target stops again. */
2983 {
2989 {
2990 /* Either this thread started a new in-line step over, or some
2991 other thread was already doing one. In either case, don't
2992 resume anything else until the step-over is finished. */
2993 }
2995 {
2996 /* A new displaced stepping sequence was started. In all-stop,
2997 we can't talk to the target anymore until it next stops. */
2998 }
3000 {
3001 /* In all-stop, but the target is always in non-stop mode.
3002 Start all other threads that are implicitly resumed too. */
3004 {
3006 {
3013 }
3016 {
3022 }
3034 }
3035 }
3037 {
3038 /* The thread wasn't started, and isn't queued, run it now. */
3044 }
3045 }
3051 /* Tell the event loop to wait for it to stop. If the target
3052 supports asynchronous execution, it'll do this from within
3053 target_resume. */
3056 }
3057 \f
3059 /* Start remote-debugging of a machine over a serial link. */
3061 void
3063 {
3069 /* Always go on waiting for the target, regardless of the mode. */
3070 /* FIXME: cagney/1999-09-23: At present it isn't possible to
3071 indicate to wait_for_inferior that a target should timeout if
3072 nothing is returned (instead of just blocking). Because of this,
3073 targets expecting an immediate response need to, internally, set
3074 things up so that the target_wait() is forced to eventually
3075 timeout. */
3076 /* FIXME: cagney/1999-09-24: It isn't possible for target_open() to
3077 differentiate to its caller what the state of the target is after
3078 the initial open has been performed. Here we're assuming that
3079 the target has stopped. It should be possible to eventually have
3080 target_open() return to the caller an indication that the target
3081 is currently running and GDB state should be set to the same as
3082 for an async run. */
3085 /* Now that the inferior has stopped, do any bookkeeping like
3086 loading shared libraries. We want to do this before normal_stop,
3087 so that the displayed frame is up to date. */
3091 }
3093 /* Initialize static vars when a new inferior begins. */
3095 void
3097 {
3098 /* These are meaningless until the first time through wait_for_inferior. */
3107 }
3109 \f
3127 /* This function is attached as a "thread_stop_requested" observer.
3128 Cleanup local state that assumed the PTID was to be resumed, and
3129 report the stop to the frontend. */
3131 static void
3133 {
3134 /* PTID was requested to stop. If the thread was already stopped,
3135 but the user/frontend doesn't know about that yet (e.g., the
3136 thread had been temporarily paused for some step-over), set up
3137 for reporting the stop now. */
3139 {
3145 /* Remove matching threads from the step-over queue, so
3146 start_step_over doesn't try to resume them
3147 automatically. */
3151 /* If the thread is stopped, but the user/frontend doesn't
3152 know about that yet, queue a pending event, as if the
3153 thread had just stopped now. Unless the thread already had
3154 a pending event. */
3156 {
3160 }
3162 /* Clear the inline-frame state, since we're re-processing the
3163 stop. */
3166 /* If this thread was paused because some other thread was
3167 doing an inline-step over, let that finish first. Once
3168 that happens, we'll restart all threads and consume pending
3169 stop events then. */
3173 /* Otherwise we can process the (new) pending event now. Set
3174 it so this pending event is considered by
3175 do_target_wait. */
3177 }
3178 }
3180 static void
3182 {
3185 }
3187 /* Delete the step resume, single-step and longjmp/exception resume
3188 breakpoints of TP. */
3190 static void
3192 {
3196 }
3198 /* If the target still has execution, call FUNC for each thread that
3199 just stopped. In all-stop, that's all the non-exited threads; in
3200 non-stop, that's the current thread, only. */
3205 static void
3207 {
3212 {
3213 /* If in non-stop mode, only the current thread stopped. */
3215 }
3216 else
3217 {
3218 /* In all-stop mode, all threads have stopped. */
3221 }
3222 }
3224 /* Delete the step resume and longjmp/exception resume breakpoints of
3225 the threads that just stopped. */
3227 static void
3229 {
3231 }
3233 /* Delete the single-step breakpoints of the threads that just
3234 stopped. */
3236 static void
3238 {
3240 }
3242 /* See infrun.h. */
3244 void
3247 {
3249 string_file stb;
3251 /* The text is split over several lines because it was getting too long.
3252 Call fprintf_unfiltered (gdb_stdlog) once so that the text is still
3253 output as a unit; we want only one timestamp printed if debug_timestamp
3254 is set. */
3270 /* This uses %s in part to handle %'s in the text, but also to avoid
3271 a gcc error: the format attribute requires a string literal. */
3273 }
3275 /* Select a thread at random, out of those which are resumed and have
3276 had events. */
3280 {
3284 {
3287 };
3289 /* First see how many events we have. Count only resumed threads
3290 that have an event pending. */
3293 num_events++;
3298 /* Now randomly pick a thread out of those that have had events. */
3307 /* Select the Nth thread that has had an event. */
3314 }
3316 /* Wrapper for target_wait that first checks whether threads have
3317 pending statuses to report before actually asking the target for
3318 more events. */
3320 static ptid_t
3322 {
3323 ptid_t event_ptid;
3326 /* First check if there is a resumed thread with a wait status
3327 pending. */
3329 {
3331 }
3332 else
3333 {
3339 /* We have a specific thread to check. */
3344 }
3349 {
3352 CORE_ADDR pc;
3358 {
3366 }
3368 {
3376 }
3379 {
3387 }
3388 }
3391 {
3393 {
3401 }
3403 /* Now that we've selected our final event LWP, un-adjust its PC
3404 if it was a software breakpoint (and the target doesn't
3405 always adjust the PC itself). */
3408 {
3418 {
3419 CORE_ADDR pc;
3423 }
3424 }
3430 /* Wake up the event loop again, until all pending events are
3431 processed. */
3435 }
3437 /* But if we don't find one, we'll have to wait. */
3441 else
3445 }
3447 /* Prepare and stabilize the inferior for detaching it. E.g.,
3448 detaching while a thread is displaced stepping is a recipe for
3449 crashing it, as nothing would readjust the PC out of the scratch
3450 pad. */
3452 void
3454 {
3460 /* Is any thread of this process displaced stepping? If not,
3461 there's nothing else to do. */
3472 {
3480 /* Flush target cache before starting to handle each event.
3481 Target was running and cache could be stale. This is just a
3482 heuristic. Running threads may modify target memory, but we
3483 don't get any event. */
3491 /* If an error happens while handling the event, propagate GDB's
3492 knowledge of the executing state to the frontend/user running
3493 state. */
3496 /* Now figure out what to do with the result of the result. */
3499 /* No error, don't finish the state yet. */
3502 /* Breakpoints and watchpoints are not installed on the target
3503 at this point, and signals are passed directly to the
3504 inferior, so this must mean the process is gone. */
3506 {
3509 }
3510 }
3513 }
3515 /* Wait for control to return from inferior to debugger.
3517 If inferior gets a signal, we may decide to start it up again
3518 instead of returning. That is why there is a loop in this function.
3519 When this function actually returns it means the inferior
3520 should be left stopped and GDB should read more commands. */
3522 void
3524 {
3526 fprintf_unfiltered
3531 /* If an error happens while handling the event, propagate GDB's
3532 knowledge of the executing state to the frontend/user running
3533 state. */
3537 {
3546 /* Flush target cache before starting to handle each event.
3547 Target was running and cache could be stale. This is just a
3548 heuristic. Running threads may modify target memory, but we
3549 don't get any event. */
3557 /* Now figure out what to do with the result of the result. */
3562 }
3564 /* No error, don't finish the state yet. */
3566 }
3568 /* Cleanup that reinstalls the readline callback handler, if the
3569 target is running in the background. If while handling the target
3570 event something triggered a secondary prompt, like e.g., a
3571 pagination prompt, we'll have removed the callback handler (see
3572 gdb_readline_wrapper_line). Need to do this as we go back to the
3573 event loop, ready to process further input. Note this has no
3574 effect if the handler hasn't actually been removed, because calling
3575 rl_callback_handler_install resets the line buffer, thus losing
3576 input. */
3578 static void
3580 {
3584 {
3585 /* We're not going back to the top level event loop yet. Don't
3586 install the readline callback, as it'd prep the terminal,
3587 readline-style (raw, noecho) (e.g., --batch). We'll install
3588 it the next time the prompt is displayed, when we're ready
3589 for input. */
3591 }
3595 }
3597 /* Clean up the FSMs of threads that are now stopped. In non-stop,
3598 that's just the event thread. In all-stop, that's all threads. */
3600 static void
3602 {
3608 {
3610 {
3618 }
3622 }
3623 }
3625 /* Helper for all_uis_check_sync_execution_done that works on the
3626 current UI. */
3628 static void
3630 {
3636 {
3640 }
3641 }
3643 /* See infrun.h. */
3645 void
3647 {
3649 {
3651 }
3652 }
3654 /* See infrun.h. */
3656 void
3658 {
3660 {
3663 }
3664 }
3666 /* Asynchronous version of wait_for_inferior. It is called by the
3667 event loop whenever a change of state is detected on the file
3668 descriptor corresponding to the target. It can be called more than
3669 once to complete a single execution command. In such cases we need
3670 to keep the state in a global variable ECSS. If it is the last time
3671 that this function is called for a single execution command, then
3672 report to the user that the inferior has stopped, and do the
3673 necessary cleanups. */
3675 void
3677 {
3685 /* Events are always processed with the main UI as current UI. This
3686 way, warnings, debug output, etc. are always consistently sent to
3687 the main console. */
3690 /* End up with readline processing input, if necessary. */
3691 {
3694 /* We're handling a live event, so make sure we're doing live
3695 debugging. If we're looking at traceframes while the target is
3696 running, we're going to need to get back to that mode after
3697 handling the event. */
3700 {
3703 }
3708 /* In non-stop mode, the user/frontend should not notice a thread
3709 switch due to internal events. Make sure we reverse to the
3710 user selected thread and frame after handling the event and
3711 running any breakpoint commands. */
3715 /* Flush target cache before starting to handle each event. Target
3716 was running and cache could be stale. This is just a heuristic.
3717 Running threads may modify target memory, but we don't get any
3718 event. */
3721 scoped_restore save_exec_dir
3731 /* If an error happens while handling the event, propagate GDB's
3732 knowledge of the executing state to the frontend/user running
3733 state. */
3737 /* Get executed before scoped_restore_current_thread above to apply
3738 still for the thread which has thrown the exception. */
3739 auto defer_bpstat_clear
3741 auto defer_delete_threads
3744 /* Now figure out what to do with the result of the result. */
3748 {
3756 {
3761 }
3764 {
3766 }
3767 else
3768 {
3778 {
3779 /* We may not find an inferior if this was a process exit. */
3782 }
3785 {
3788 }
3789 }
3790 }
3795 /* No error, don't finish the thread states yet. */
3798 /* This scope is used to ensure that readline callbacks are
3799 reinstalled here. */
3800 }
3802 /* If a UI was in sync execution mode, and now isn't, restore its
3803 prompt (a synchronous execution command has finished, and we're
3804 ready for input). */
3808 && exec_done_display_p
3812 }
3814 /* Record the frame and location we're currently stepping through. */
3815 void
3817 {
3825 }
3827 /* Clear context switchable stepping state. */
3829 void
3831 {
3836 }
3838 /* Set the cached copy of the last ptid/waitstatus. */
3840 void
3842 {
3845 }
3847 /* Return the cached copy of the last pid/waitstatus returned by
3848 target_wait()/deprecated_target_wait_hook(). The data is actually
3849 cached by handle_inferior_event(), which gets called immediately
3850 after target_wait()/deprecated_target_wait_hook(). */
3852 void
3854 {
3857 }
3859 void
3861 {
3863 }
3865 /* Switch thread contexts. */
3867 static void
3869 {
3873 {
3878 }
3881 }
3883 /* If the target can't tell whether we've hit breakpoints
3884 (target_supports_stopped_by_sw_breakpoint), and we got a SIGTRAP,
3885 check whether that could have been caused by a breakpoint. If so,
3886 adjust the PC, per gdbarch_decr_pc_after_break. */
3888 static void
3891 {
3896 /* If we've hit a breakpoint, we'll normally be stopped with SIGTRAP. If
3897 we aren't, just return.
3899 We assume that waitkinds other than TARGET_WAITKIND_STOPPED are not
3900 affected by gdbarch_decr_pc_after_break. Other waitkinds which are
3901 implemented by software breakpoints should be handled through the normal
3902 breakpoint layer.
3904 NOTE drow/2004-01-31: On some targets, breakpoints may generate
3905 different signals (SIGILL or SIGEMT for instance), but it is less
3906 clear where the PC is pointing afterwards. It may not match
3907 gdbarch_decr_pc_after_break. I don't know any specific target that
3908 generates these signals at breakpoints (the code has been in GDB since at
3909 least 1992) so I can not guess how to handle them here.
3911 In earlier versions of GDB, a target with
3912 gdbarch_have_nonsteppable_watchpoint would have the PC after hitting a
3913 watchpoint affected by gdbarch_decr_pc_after_break. I haven't found any
3914 target with both of these set in GDB history, and it seems unlikely to be
3915 correct, so gdbarch_have_nonsteppable_watchpoint is not checked here. */
3923 /* In reverse execution, when a breakpoint is hit, the instruction
3924 under it has already been de-executed. The reported PC always
3925 points at the breakpoint address, so adjusting it further would
3926 be wrong. E.g., consider this case on a decr_pc_after_break == 1
3927 architecture:
3929 B1 0x08000000 : INSN1
3930 B2 0x08000001 : INSN2
3931 0x08000002 : INSN3
3932 PC -> 0x08000003 : INSN4
3934 Say you're stopped at 0x08000003 as above. Reverse continuing
3935 from that point should hit B2 as below. Reading the PC when the
3936 SIGTRAP is reported should read 0x08000001 and INSN2 should have
3937 been de-executed already.
3939 B1 0x08000000 : INSN1
3940 B2 PC -> 0x08000001 : INSN2
3941 0x08000002 : INSN3
3942 0x08000003 : INSN4
3944 We can't apply the same logic as for forward execution, because
3945 we would wrongly adjust the PC to 0x08000000, since there's a
3946 breakpoint at PC - 1. We'd then report a hit on B1, although
3947 INSN1 hadn't been de-executed yet. Doing nothing is the correct
3948 behaviour. */
3952 /* If the target can tell whether the thread hit a SW breakpoint,
3953 trust it. Targets that can tell also adjust the PC
3954 themselves. */
3958 /* Note that relying on whether a breakpoint is planted in memory to
3959 determine this can fail. E.g,. the breakpoint could have been
3960 removed since. Or the thread could have been told to step an
3961 instruction the size of a breakpoint instruction, and only
3962 _after_ was a breakpoint inserted at its address. */
3964 /* If this target does not decrement the PC after breakpoints, then
3965 we have nothing to do. */
3975 /* Find the location where (if we've hit a breakpoint) the
3976 breakpoint would be. */
3979 /* If the target can't tell whether a software breakpoint triggered,
3980 fallback to figuring it out based on breakpoints we think were
3981 inserted in the target, and on whether the thread was stepped or
3982 continued. */
3984 /* Check whether there actually is a software breakpoint inserted at
3985 that location.
3987 If in non-stop mode, a race condition is possible where we've
3988 removed a breakpoint, but stop events for that breakpoint were
3989 already queued and arrive later. To suppress those spurious
3990 SIGTRAPs, we keep a list of such breakpoint locations for a bit,
3991 and retire them after a number of stop events are reported. Note
3992 this is an heuristic and can thus get confused. The real fix is
3993 to get the "stopped by SW BP and needs adjustment" info out of
3994 the target/kernel (and thus never reach here; see above). */
3998 {
4002 restore_operation_disable.emplace
4005 /* When using hardware single-step, a SIGTRAP is reported for both
4006 a completed single-step and a software breakpoint. Need to
4007 differentiate between the two, as the latter needs adjusting
4008 but the former does not.
4010 The SIGTRAP can be due to a completed hardware single-step only if
4011 - we didn't insert software single-step breakpoints
4012 - this thread is currently being stepped
4014 If any of these events did not occur, we must have stopped due
4015 to hitting a software breakpoint, and have to back up to the
4016 breakpoint address.
4018 As a special case, we could have hardware single-stepped a
4019 software breakpoint. In this case (prev_pc == breakpoint_pc),
4020 we also need to back up to the breakpoint address. */
4027 }
4028 }
4030 static int
4032 {
4036 {
4041 }
4044 }
4046 /* If the event thread has the stop requested flag set, pretend it
4047 stopped for a GDB_SIGNAL_0 (i.e., as if it stopped due to
4048 target_stop). */
4050 static bool
4052 {
4054 {
4059 }
4061 }
4063 /* Auxiliary function that handles syscall entry/return events.
4064 It returns 1 if the inferior should keep going (and GDB
4065 should ignore the event), or 0 if the event deserves to be
4066 processed. */
4068 static int
4070 {
4082 {
4085 syscall_number);
4096 {
4097 /* Catchpoint hit. */
4099 }
4100 }
4105 /* If no catchpoint triggered for this, then keep going. */
4108 }
4110 /* Lazily fill in the execution_control_state's stop_func_* fields. */
4112 static void
4115 {
4117 {
4118 /* Don't care about return value; stop_func_start and stop_func_name
4119 will both be 0 if it doesn't work. */
4124 ecs->stop_func_start
4132 }
4133 }
4136 /* Return the STOP_SOON field of the inferior pointed at by ECS. */
4138 static enum stop_kind
4140 {
4145 }
4147 /* Wait for one event. Store the resulting waitstatus in WS, and
4148 return the event ptid. */
4150 static ptid_t
4152 {
4153 ptid_t event_ptid;
4158 /* Flush target cache before starting to handle each event.
4159 Target was running and cache could be stale. This is just a
4160 heuristic. Running threads may modify target memory, but we
4161 don't get any event. */
4166 else
4173 }
4175 /* Generate a wrapper for target_stopped_by_REASON that works on PTID
4176 instead of the current thread. */
4177 #define THREAD_STOPPED_BY(REASON) \
4178 static int \
4179 thread_stopped_by_ ## REASON (ptid_t ptid) \
4180 { \
4181 scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid); \
4182 inferior_ptid = ptid; \
4183 \
4184 return target_stopped_by_ ## REASON (); \
4185 }
4187 /* Generate thread_stopped_by_watchpoint. */
4189 /* Generate thread_stopped_by_sw_breakpoint. */
4191 /* Generate thread_stopped_by_hw_breakpoint. */
4194 /* Save the thread's event and stop reason to process it later. */
4196 static void
4198 {
4200 {
4209 }
4211 /* Record for later. */
4220 {
4226 {
4229 }
4232 {
4235 }
4238 {
4241 }
4244 pc))
4245 {
4248 }
4251 pc))
4252 {
4255 }
4258 {
4261 }
4262 }
4263 }
4265 /* See infrun.h. */
4267 void
4269 {
4270 /* We may need multiple passes to discover all threads. */
4279 scoped_restore_current_thread restore_thread;
4284 /* Request threads to stop, and then wait for the stops. Because
4285 threads we already know about can spawn more threads while we're
4286 trying to stop them, and we only learn about new threads when we
4287 update the thread list, do this in a loop, and keep iterating
4288 until two passes find no threads that need to be stopped. */
4290 {
4293 "infrun: stop_all_threads, pass=%d, "
4296 {
4297 ptid_t event_ptid;
4303 /* Go through all threads looking for threads that we need
4304 to tell the target to stop. */
4306 {
4308 {
4309 /* If already stopping, don't request a stop again.
4310 We just haven't seen the notification yet. */
4312 {
4315 "infrun: %s executing, "
4320 }
4321 else
4322 {
4325 "infrun: %s executing, "
4328 }
4332 }
4333 else
4334 {
4340 /* The thread may be not executing, but still be
4341 resumed with a pending status to process. */
4343 }
4344 }
4349 /* If we find new threads on the second iteration, restart
4350 over. We want to see two iterations in a row with all
4351 threads stopped. */
4357 {
4362 }
4368 {
4369 /* All resumed threads exited
4370 or one thread/process exited/signalled. */
4371 }
4372 else
4373 {
4383 /* This may be the first time we see the inferior report
4384 a stop. */
4387 {
4390 }
4394 {
4395 /* We caught the event that we intended to catch, so
4396 there's no event pending. */
4401 {
4402 /* Add it back to the step-over queue. */
4404 {
4406 "infrun: displaced-step of %s "
4407 "canceled: adding back to the "
4410 }
4413 }
4414 }
4415 else
4416 {
4421 {
4425 "infrun: target_wait %s, saving "
4431 }
4433 /* Record for later. */
4440 {
4441 /* Add it back to the step-over queue. */
4444 }
4450 {
4452 "infrun: saved stop_pc=%s for %s "
4458 }
4459 }
4460 }
4461 }
4462 }
4466 }
4468 /* Handle a TARGET_WAITKIND_NO_RESUMED event. */
4470 static int
4472 {
4474 {
4479 {
4481 {
4484 }
4485 }
4487 {
4488 /* There were no unwaited-for children left in the target, but,
4489 we're not synchronously waiting for events either. Just
4490 ignore. */
4494 "infrun: TARGET_WAITKIND_NO_RESUMED "
4498 }
4499 }
4501 /* Otherwise, if we were running a synchronous execution command, we
4502 may need to cancel it and give the user back the terminal.
4504 In non-stop mode, the target can't tell whether we've already
4505 consumed previous stop events, so it can end up sending us a
4506 no-resumed event like so:
4508 #0 - thread 1 is left stopped
4510 #1 - thread 2 is resumed and hits breakpoint
4511 -> TARGET_WAITKIND_STOPPED
4513 #2 - thread 3 is resumed and exits
4514 this is the last resumed thread, so
4515 -> TARGET_WAITKIND_NO_RESUMED
4517 #3 - gdb processes stop for thread 2 and decides to re-resume
4518 it.
4520 #4 - gdb processes the TARGET_WAITKIND_NO_RESUMED event.
4521 thread 2 is now resumed, so the event should be ignored.
4523 IOW, if the stop for thread 2 doesn't end a foreground command,
4524 then we need to ignore the following TARGET_WAITKIND_NO_RESUMED
4525 event. But it could be that the event meant that thread 2 itself
4526 (or whatever other thread was the last resumed thread) exited.
4528 To address this we refresh the thread list and check whether we
4529 have resumed threads _now_. In the example above, this removes
4530 thread 3 from the thread list. If thread 2 was re-resumed, we
4531 ignore this event. If we find no thread resumed, then we cancel
4532 the synchronous command show "no unwaited-for " to the user. */
4536 {
4539 {
4540 /* There were no unwaited-for children left in the target at
4541 some point, but there are now. Just ignore. */
4544 "infrun: TARGET_WAITKIND_NO_RESUMED "
4548 }
4549 }
4551 /* Note however that we may find no resumed thread because the whole
4552 process exited meanwhile (thus updating the thread list results
4553 in an empty thread list). In this case we know we'll be getting
4554 a process exit event shortly. */
4556 {
4562 {
4565 "infrun: TARGET_WAITKIND_NO_RESUMED "
4569 }
4570 }
4572 /* Go ahead and report the event. */
4574 }
4576 /* Given an execution control state that has been freshly filled in by
4577 an event from the inferior, figure out what it means and take
4578 appropriate action.
4580 The alternatives are:
4582 1) stop_waiting and return; to really stop and return to the
4583 debugger.
4585 2) keep_going and return; to wait for the next event (set
4586 ecs->event_thread->stepping_over_breakpoint to 1 to single step
4587 once). */
4589 static void
4591 {
4592 /* Make sure that all temporary struct value objects that were
4593 created during the handling of the event get deleted at the
4594 end. */
4595 scoped_value_mark free_values;
4604 {
4605 /* We had an event in the inferior, but we are not interested in
4606 handling it at this level. The lower layers have already
4607 done what needs to be done, if anything.
4609 One of the possible circumstances for this is when the
4610 inferior produces output for the console. The inferior has
4611 not stopped, and we are ignoring the event. Another possible
4612 circumstance is any event which the lower level knows will be
4613 reported multiple times without an intervening resume. */
4616 }
4619 {
4622 }
4628 /* Cache the last pid/waitstatus. */
4631 /* Always clear state belonging to the previous time we stopped. */
4635 {
4636 /* No unwaited-for children left. IOW, all resumed children
4637 have exited. */
4641 }
4645 {
4647 /* If it's a new thread, add it to the thread database. */
4651 /* Disable range stepping. If the next step request could use a
4652 range, this will be end up re-enabled then. */
4654 }
4656 /* Dependent on valid ECS->EVENT_THREAD. */
4659 /* Dependent on the current PC value modified by adjust_pc_after_break. */
4664 /* First, distinguish signals caused by the debugger from signals
4665 that have to do with the program's own actions. Note that
4666 breakpoint insns may cause SIGTRAP or SIGILL or SIGEMT, depending
4667 on the operating system version. Here we detect when a SIGILL or
4668 SIGEMT is really a breakpoint and change it to SIGTRAP. We do
4669 something similar for SIGSEGV, since a SIGSEGV will be generated
4670 when we're trying to execute a breakpoint instruction on a
4671 non-executable stack. This happens for call dummy breakpoints
4672 for architectures like SPARC that place call dummies on the
4673 stack. */
4678 {
4683 {
4688 }
4689 }
4691 /* Mark the non-executing threads accordingly. In all-stop, all
4692 threads of all processes are stopped when we get any event
4693 reported. In non-stop mode, only the event thread stops. */
4694 {
4695 ptid_t mark_ptid;
4701 {
4702 /* If we're handling a process exit in non-stop mode, even
4703 though threads haven't been deleted yet, one would think
4704 that there is nothing to do, as threads of the dead process
4705 will be soon deleted, and threads of any other process were
4706 left running. However, on some targets, threads survive a
4707 process exit event. E.g., for the "checkpoint" command,
4708 when the current checkpoint/fork exits, linux-fork.c
4709 automatically switches to another fork from within
4710 target_mourn_inferior, by associating the same
4711 inferior/thread to another fork. We haven't mourned yet at
4712 this point, but we must mark any threads left in the
4713 process as not-executing so that finish_thread_state marks
4714 them stopped (in the user's perspective) if/when we present
4715 the stop to the user. */
4717 }
4718 else
4723 /* Likewise the resumed flag. */
4725 }
4728 {
4731 /* Ignore gracefully during startup of the inferior, as it might
4732 be the shell which has just loaded some objects, otherwise
4733 add the symbols for the newly loaded objects. Also ignore at
4734 the beginning of an attach or remote session; we will query
4735 the full list of libraries once the connection is
4736 established. */
4740 {
4756 {
4757 /* A catchpoint triggered. */
4760 }
4762 /* If requested, stop when the dynamic linker notifies
4763 gdb of events. This allows the user to get control
4764 and place breakpoints in initializer routines for
4765 dynamically loaded objects (among other things). */
4768 {
4769 /* Make sure we print "Stopped due to solib-event" in
4770 normal_stop. */
4775 }
4776 }
4778 /* If we are skipping through a shell, or through shared library
4779 loading that we aren't interested in, resume the program. If
4780 we're running the program normally, also resume. */
4782 {
4783 /* Loading of shared libraries might have changed breakpoint
4784 addresses. Make sure new breakpoints are inserted. */
4790 }
4792 /* But stop if we're attaching or setting up a remote
4793 connection. */
4796 {
4801 }
4830 /* Clearing any previous state of convenience variables. */
4834 {
4835 /* Record the exit code in the convenience variable $_exitcode, so
4836 that the user can inspect this again later. */
4840 /* Also record this in the inferior itself. */
4844 /* Support the --return-child-result option. */
4848 }
4849 else
4850 {
4854 {
4855 /* Set the value of the internal variable $_exitsignal,
4856 which holds the signal uncaught by the inferior. */
4860 }
4861 else
4862 {
4863 /* We don't have access to the target's method used for
4864 converting between signal numbers (GDB's internal
4865 representation <-> target's representation).
4866 Therefore, we cannot do a good job at displaying this
4867 information to the user. It's better to just warn
4868 her about it (if infrun debugging is enabled), and
4869 give up. */
4873 }
4876 }
4884 /* The following are the only cases in which we keep going;
4885 the above cases end in a continue or goto. */
4888 /* Check whether the inferior is displaced stepping. */
4889 {
4893 /* If checking displaced stepping is supported, and thread
4894 ecs->ptid is displaced stepping. */
4896 {
4900 CORE_ADDR parent_pc;
4902 /* GDB has got TARGET_WAITKIND_FORKED or TARGET_WAITKIND_VFORKED,
4903 indicating that the displaced stepping of syscall instruction
4904 has been done. Perform cleanup for parent process here. Note
4905 that this operation also cleans up the child process for vfork,
4906 because their pages are shared. */
4908 /* Start a new step-over in another thread if there's one
4909 that needs it. */
4913 {
4917 /* Restore scratch pad for child process. */
4919 }
4921 /* Since the vfork/fork syscall instruction was executed in the scratchpad,
4922 the child's PC is also within the scratchpad. Set the child's PC
4923 to the parent's PC value, which has already been fixed up.
4924 FIXME: we use the parent's aspace here, although we're touching
4925 the child, because the child hasn't been added to the inferior
4926 list yet at this point. */
4928 child_regcache
4930 gdbarch,
4932 /* Read PC value of parent process. */
4943 }
4944 }
4948 /* Immediately detach breakpoints from the child before there's
4949 any chance of letting the user delete breakpoints from the
4950 breakpoint lists. If we don't do this early, it's easy to
4951 leave left over traps in the child, vis: "break foo; catch
4952 fork; c; <fork>; del; c; <child calls foo>". We only follow
4953 the fork on the last `continue', and by that time the
4954 breakpoint at "foo" is long gone from the breakpoint table.
4955 If we vforked, then we don't need to unpatch here, since both
4956 parent and child are sharing the same memory pages; we'll
4957 need to unpatch at follow/detach time instead to be certain
4958 that new breakpoints added between catchpoint hit time and
4959 vfork follow are detached. */
4961 {
4962 /* This won't actually modify the breakpoint list, but will
4963 physically remove the breakpoints from the child. */
4965 }
4969 /* In case the event is caught by a catchpoint, remember that
4970 the event is to be followed at the next resume of the thread,
4971 and not immediately. */
4985 /* If no catchpoint triggered for this, then keep going. Note
4986 that we're interested in knowing the bpstat actually causes a
4987 stop, not just if it may explain the signal. Software
4988 watchpoints, for example, always appear in the bpstat. */
4990 {
4992 int follow_child
5002 /* At this point, the parent is marked running, and the
5003 child is marked stopped. */
5005 /* If not resuming the parent, mark it stopped. */
5009 /* If resuming the child, mark it running. */
5013 /* In non-stop mode, also resume the other branch. */
5016 {
5019 else
5025 }
5029 else
5037 else
5040 }
5045 /* Done with the shared memory region. Re-insert breakpoints in
5046 the parent, and keep going. */
5056 /* This also takes care of reinserting breakpoints in the
5057 previously locked inferior. */
5063 /* Note we can't read registers yet (the stop_pc), because we
5064 don't yet know the inferior's post-exec architecture.
5065 'stop_pc' is explicitly read below instead. */
5068 /* Do whatever is necessary to the parent branch of the vfork. */
5071 /* This causes the eventpoints and symbol table to be reset.
5072 Must do this now, before trying to determine whether to
5073 stop. */
5076 /* In follow_exec we may have deleted the original thread and
5077 created a new one. Make sure that the event thread is the
5078 execd thread for that case (this is a nop otherwise). */
5089 /* Note that this may be referenced from inside
5090 bpstat_stop_status above, through inferior_has_execd. */
5097 /* If no catchpoint triggered for this, then keep going. */
5099 {
5103 }
5107 /* Be careful not to try to gather much state about a thread
5108 that's in a syscall. It's frequently a losing proposition. */
5110 /* Getting the current syscall number. */
5115 /* Before examining the threads further, step this thread to
5116 get it entirely out of the syscall. (We get notice of the
5117 event when the thread is just on the verge of exiting a
5118 syscall. Stepping one instruction seems to get it back
5119 into user code.) */
5130 /* Reverse execution: target ran out of history info. */
5132 /* Switch to the stopped thread. */
5147 }
5148 }
5150 /* Restart threads back to what they were trying to do back when we
5151 paused them for an in-line step-over. The EVENT_THREAD thread is
5152 ignored. */
5154 static void
5156 {
5157 /* In case the instruction just stepped spawned a new thread. */
5161 {
5163 {
5166 "infrun: restart threads: "
5170 }
5173 {
5176 "infrun: restart threads: "
5180 }
5183 {
5190 }
5193 {
5196 "infrun: restart threads: "
5201 }
5205 {
5208 "infrun: restart threads: "
5213 }
5217 /* If some thread needs to start a step-over at this point, it
5218 should still be in the step-over queue, and thus skipped
5219 above. */
5221 {
5223 "thread [%s] needs a step-over, but not in "
5226 }
5229 {
5235 }
5236 else
5237 {
5248 }
5249 }
5250 }
5252 /* Callback for iterate_over_threads. Find a resumed thread that has
5253 a pending waitstatus. */
5255 static int
5258 {
5261 }
5263 /* Called when we get an event that may finish an in-line or
5264 out-of-line (displaced stepping) step-over started previously.
5265 Return true if the event is processed and we should go back to the
5266 event loop; false if the caller should continue processing the
5267 event. */
5269 static int
5271 {
5280 {
5281 /* If we're stepping over a breakpoint with all threads locked,
5282 then only the thread that was stepped should be reporting
5283 back an event. */
5287 }
5292 /* Start a new step-over in another thread if there's one that
5293 needs it. */
5296 /* If we were stepping over a breakpoint before, and haven't started
5297 a new in-line step-over sequence, then restart all other threads
5298 (except the event thread). We can't do this in all-stop, as then
5299 e.g., we wouldn't be able to issue any other remote packet until
5300 these other threads stop. */
5302 {
5305 /* If we only have threads with pending statuses, the restart
5306 below won't restart any thread and so nothing re-inserts the
5307 breakpoint we just stepped over. But we need it inserted
5308 when we later process the pending events, otherwise if
5309 another thread has a pending event for this breakpoint too,
5310 we'd discard its event (because the breakpoint that
5311 originally caused the event was no longer inserted). */
5317 /* If we have events pending, go through handle_inferior_event
5318 again, picking up a pending event at random. This avoids
5319 thread starvation. */
5321 /* But not if we just stepped over a watchpoint in order to let
5322 the instruction execute so we can evaluate its expression.
5323 The set of watchpoints that triggered is recorded in the
5324 breakpoint objects themselves (see bp->watchpoint_triggered).
5325 If we processed another event first, that other event could
5326 clobber this info. */
5331 NULL);
5333 {
5338 {
5340 "infrun: found resumed threads with "
5342 }
5346 /* Record the event thread's event for later. */
5348 /* This was cleared early, by handle_inferior_event. Set it
5349 so this pending event is considered by
5350 do_target_wait. */
5359 {
5361 "infrun: saved stop_pc=%s for %s "
5367 }
5369 /* This in-line step-over finished; clear this so we won't
5370 start a new one. This is what handle_signal_stop would
5371 do, if we returned false. */
5374 /* Wake up the event loop again. */
5379 }
5380 }
5383 }
5385 /* Come here when the program has stopped with a signal. */
5387 static void
5389 {
5400 /* Do we need to clean up the state of a thread that has
5401 completed a displaced single-step? (Doing so usually affects
5402 the PC, so do it here, before we set stop_pc.) */
5406 /* If we either finished a single-step or hit a breakpoint, but
5407 the user wanted this thread to be stopped, pretend we got a
5408 SIG0 (generic unsignaled stop). */
5417 {
5428 {
5429 CORE_ADDR addr;
5437 else
5440 }
5441 }
5443 /* This is originated from start_remote(), start_inferior() and
5444 shared libraries hook functions. */
5447 {
5454 }
5456 /* This originates from attach_command(). We need to overwrite
5457 the stop_signal here, because some kernels don't ignore a
5458 SIGSTOP in a subsequent ptrace(PTRACE_CONT,SIGSTOP) call.
5459 See more comments in inferior.h. On the other hand, if we
5460 get a non-SIGSTOP, report it to the user - assume the backend
5461 will handle the SIGSTOP if it should show up later.
5463 Also consider that the attach is complete when we see a
5464 SIGTRAP. Some systems (e.g. Windows), and stubs supporting
5465 target extended-remote report it instead of a SIGSTOP
5466 (e.g. gdbserver). We already rely on SIGTRAP being our
5467 signal, so this is no exception.
5469 Also consider that the attach is complete when we see a
5470 GDB_SIGNAL_0. In non-stop mode, GDB will explicitly tell
5471 the target to stop all threads of the inferior, in case the
5472 low level attach operation doesn't stop them implicitly. If
5473 they weren't stopped implicitly, then the stub will report a
5474 GDB_SIGNAL_0, meaning: stopped for no particular reason
5475 other than GDB's request. */
5480 {
5485 }
5487 /* See if something interesting happened to the non-current thread. If
5488 so, then switch to that thread. */
5490 {
5498 }
5500 /* At this point, get hold of the now-current thread's frame. */
5504 /* Pull the single step breakpoints out of the target. */
5506 {
5508 CORE_ADDR pc;
5515 /* However, before doing so, if this single-step breakpoint was
5516 actually for another thread, set this thread up for moving
5517 past it. */
5520 {
5522 {
5524 {
5526 "infrun: [%s] hit another thread's "
5529 }
5531 }
5532 }
5533 else
5534 {
5536 {
5538 "infrun: [%s] hit its "
5541 }
5542 }
5543 }
5550 else
5553 /* If necessary, step over this watchpoint. We'll be back to display
5554 it in a moment. */
5556 && (target_have_steppable_watchpoint
5558 {
5559 /* At this point, we are stopped at an instruction which has
5560 attempted to write to a piece of memory under control of
5561 a watchpoint. The instruction hasn't actually executed
5562 yet. If we were to evaluate the watchpoint expression
5563 now, we would get the old value, and therefore no change
5564 would seem to have occurred.
5566 In order to make watchpoints work `right', we really need
5567 to complete the memory write, and then evaluate the
5568 watchpoint expression. We do this by single-stepping the
5569 target.
5571 It may not be necessary to disable the watchpoint to step over
5572 it. For example, the PA can (with some kernel cooperation)
5573 single step over a watchpoint without disabling the watchpoint.
5575 It is far more common to need to disable a watchpoint to step
5576 the inferior over it. If we have non-steppable watchpoints,
5577 we must disable the current watchpoint; it's simplest to
5578 disable all watchpoints.
5580 Any breakpoint at PC must also be stepped over -- if there's
5581 one, it will have already triggered before the watchpoint
5582 triggered, and we either already reported it to the user, or
5583 it didn't cause a stop and we called keep_going. In either
5584 case, if there was a breakpoint at PC, we must be trying to
5585 step past it. */
5589 }
5599 /* Hide inlined functions starting here, unless we just performed stepi or
5600 nexti. After stepi and nexti, always show the innermost frame (not any
5601 inline function call sites). */
5603 {
5607 /* skip_inline_frames is expensive, so we avoid it if we can
5608 determine that the address is one where functions cannot have
5609 been inlined. This improves performance with inferiors that
5610 load a lot of shared libraries, because the solib event
5611 breakpoint is defined as the address of a function (i.e. not
5612 inline). Note that we have to check the previous PC as well
5613 as the current one to catch cases when we have just
5614 single-stepped off a breakpoint prior to reinstating it.
5615 Note that we're assuming that the code we single-step to is
5616 not inline, but that's not definitive: there's nothing
5617 preventing the event breakpoint function from containing
5618 inlined code, and the single-step ending up there. If the
5619 user had set a breakpoint on that inlined code, the missing
5620 skip_inline_frames call would break things. Fortunately
5621 that's an extremely unlikely scenario. */
5630 {
5636 /* Re-fetch current thread's frame in case that invalidated
5637 the frame cache. */
5640 }
5641 }
5647 {
5648 /* We're trying to step off a breakpoint. Turns out that we're
5649 also on an instruction that needs to be stepped multiple
5650 times before it's been fully executing. E.g., architectures
5651 with a delay slot. It needs to be stepped twice, once for
5652 the instruction and once for the delay slot. */
5653 int step_through_delay
5660 {
5661 /* The user issued a continue when stopped at a breakpoint.
5662 Set up for another trap and get out of here. */
5666 }
5668 {
5669 /* The user issued a step when stopped at a breakpoint.
5670 Maybe we should stop, maybe we should not - the delay
5671 slot *might* correspond to a line of source. In any
5672 case, don't decide that here, just set
5673 ecs->stepping_over_breakpoint, making sure we
5674 single-step again before breakpoints are re-inserted. */
5676 }
5677 }
5679 /* See if there is a breakpoint/watchpoint/catchpoint/etc. that
5680 handles this event. */
5686 /* Following in case break condition called a
5687 function. */
5690 /* This is where we handle "moribund" watchpoints. Unlike
5691 software breakpoints traps, hardware watchpoint traps are
5692 always distinguishable from random traps. If no high-level
5693 watchpoint is associated with the reported stop data address
5694 anymore, then the bpstat does not explain the signal ---
5695 simply make sure to ignore it if `stopped_by_watchpoint' is
5696 set. */
5701 GDB_SIGNAL_TRAP)
5704 "infrun: no user watchpoint explains "
5707 /* NOTE: cagney/2003-03-29: These checks for a random signal
5708 at one stage in the past included checks for an inferior
5709 function call's call dummy's return breakpoint. The original
5710 comment, that went with the test, read:
5712 ``End of a stack dummy. Some systems (e.g. Sony news) give
5713 another signal besides SIGTRAP, so check here as well as
5714 above.''
5716 If someone ever tries to get call dummys on a
5717 non-executable stack to work (where the target would stop
5718 with something like a SIGSEGV), then those tests might need
5719 to be re-instated. Given, however, that the tests were only
5720 enabled when momentary breakpoints were not being used, I
5721 suspect that it won't be the case.
5723 NOTE: kettenis/2004-02-05: Indeed such checks don't seem to
5724 be necessary for call dummies on a non-executable stack on
5725 SPARC. */
5727 /* See if the breakpoints module can explain the signal. */
5728 random_signal
5732 /* Maybe this was a trap for a software breakpoint that has since
5733 been removed. */
5735 {
5738 {
5742 /* Re-adjust PC to what the program would see if GDB was not
5743 debugging it. */
5747 {
5749 restore_operation_disable;
5752 restore_operation_disable.emplace
5757 }
5758 }
5759 else
5760 {
5761 /* A delayed software breakpoint event. Ignore the trap. */
5764 "infrun: delayed software breakpoint "
5767 }
5768 }
5770 /* Maybe this was a trap for a hardware breakpoint/watchpoint that
5771 has since been removed. */
5773 {
5774 /* A delayed hardware breakpoint event. Ignore the trap. */
5777 "infrun: delayed hardware breakpoint/watchpoint "
5780 }
5782 /* If not, perhaps stepping/nexting can. */
5787 /* Perhaps the thread hit a single-step breakpoint of _another_
5788 thread. Single-step breakpoints are transparent to the
5789 breakpoints module. */
5793 /* No? Perhaps we got a moribund watchpoint. */
5797 /* Always stop if the user explicitly requested this thread to
5798 remain stopped. */
5800 {
5804 }
5806 /* For the program's own signals, act according to
5807 the signal handling tables. */
5810 {
5811 /* Signal not for debugging purposes. */
5821 /* Always stop on signals if we're either just gaining control
5822 of the program, or the user explicitly requested this thread
5823 to remain stopped. */
5828 {
5831 }
5833 /* Notify observers the signal has "handle print" set. Note we
5834 returned early above if stopping; normal_stop handles the
5835 printing in that case. */
5837 {
5838 /* The signal table tells us to print about this signal. */
5842 }
5844 /* Clear the signal if it should not be passed. */
5851 {
5852 /* We were just starting a new sequence, attempting to
5853 single-step off of a breakpoint and expecting a SIGTRAP.
5854 Instead this signal arrives. This signal will take us out
5855 of the stepping range so GDB needs to remember to, when
5856 the signal handler returns, resume stepping off that
5857 breakpoint. */
5858 /* To simplify things, "continue" is forced to use the same
5859 code paths as single-step - set a breakpoint at the
5860 signal return address and then, once hit, step off that
5861 breakpoint. */
5864 "infrun: signal arrived while stepping over "
5869 /* Reset trap_expected to ensure breakpoints are re-inserted. */
5872 /* If we were nexting/stepping some other thread, switch to
5873 it, so that we don't continue it, losing control. */
5877 }
5886 {
5887 /* The inferior is about to take a signal that will take it
5888 out of the single step range. Set a breakpoint at the
5889 current PC (which is presumably where the signal handler
5890 will eventually return) and then allow the inferior to
5891 run free.
5893 Note that this is only needed for a signal delivered
5894 while in the single-step range. Nested signals aren't a
5895 problem as they eventually all return. */
5898 "infrun: signal may take us out of "
5904 /* Reset trap_expected to ensure breakpoints are re-inserted. */
5908 }
5910 /* Note: step_resume_breakpoint may be non-NULL. This occures
5911 when either there's a nested signal, or when there's a
5912 pending signal enabled just as the signal handler returns
5913 (leaving the inferior at the step-resume-breakpoint without
5914 actually executing it). Either way continue until the
5915 breakpoint is really hit. */
5918 {
5924 }
5926 }
5929 }
5931 /* Come here when we've got some debug event / signal we can explain
5932 (IOW, not a random signal), and test whether it should cause a
5933 stop, or whether we should resume the inferior (transparently).
5934 E.g., could be a breakpoint whose condition evaluates false; we
5935 could be still stepping within the line; etc. */
5937 static void
5939 {
5943 CORE_ADDR jmp_buf_pc;
5946 /* Handle cases caused by hitting a breakpoint. */
5954 {
5956 }
5958 /* A few breakpoint types have callbacks associated (e.g.,
5959 bp_jit_event). Run them now. */
5962 /* If we hit an internal event that triggers symbol changes, the
5963 current frame will be invalidated within bpstat_what (e.g., if we
5964 hit an internal solib event). Re-fetch it. */
5969 {
5971 /* If we hit the breakpoint at longjmp while stepping, we
5972 install a momentary breakpoint at the target of the
5973 jmp_buf. */
5982 {
5985 /* If we set the longjmp breakpoint via a SystemTap probe,
5986 then use it to extract the arguments. The destination PC
5987 is the third argument to the probe. */
5990 {
5993 }
5997 {
6000 "infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME "
6004 }
6006 /* Insert a breakpoint at resume address. */
6008 }
6009 else
6015 {
6018 /* There are several cases to consider.
6020 1. The initiating frame no longer exists. In this case we
6021 must stop, because the exception or longjmp has gone too
6022 far.
6024 2. The initiating frame exists, and is the same as the
6025 current frame. We stop, because the exception or longjmp
6026 has been caught.
6028 3. The initiating frame exists and is different from the
6029 current frame. This means the exception or longjmp has
6030 been caught beneath the initiating frame, so keep going.
6032 4. longjmp breakpoint has been placed just to protect
6033 against stale dummy frames and user is not interested in
6034 stopping around longjmps. */
6045 {
6049 {
6050 /* Case 4. */
6053 }
6054 }
6059 {
6060 struct frame_id current_id
6064 {
6065 /* Case 2. Fall through. */
6066 }
6067 else
6068 {
6069 /* Case 3. */
6072 }
6073 }
6075 /* For Cases 1 and 2, remove the step-resume breakpoint, if it
6076 exists. */
6080 }
6087 /* Still need to check other stuff, at least the case where we
6088 are stepping and step out of the right range. */
6098 {
6101 /* We are finishing a function in reverse, and just hit the
6102 step-resume breakpoint at the start address of the
6103 function, and we're almost there -- just need to back up
6104 by one more single-step, which should take us back to the
6105 function call. */
6109 }
6113 {
6114 /* We are stepping over a function call in reverse, and just
6115 hit the step-resume breakpoint at the start address of
6116 the function. Go back to single-stepping, which should
6117 take us back to the function call. */
6121 }
6129 /* Assume the thread stopped for a breapoint. We'll still check
6130 whether a/the breakpoint is there when the thread is next
6131 resumed. */
6142 /* Assume the thread stopped for a breapoint. We'll still check
6143 whether a/the breakpoint is there when the thread is next
6144 resumed. */
6155 {
6156 /* Back when the step-resume breakpoint was inserted, we
6157 were trying to single-step off a breakpoint. Go back to
6158 doing that. */
6163 }
6168 }
6170 /* If we stepped a permanent breakpoint and we had a high priority
6171 step-resume breakpoint for the address we stepped, but we didn't
6172 hit it, then we must have stepped into the signal handler. The
6173 step-resume was only necessary to catch the case of _not_
6174 stepping into the handler, so delete it, and fall through to
6175 checking whether the step finished. */
6177 {
6185 {
6188 "infrun: stepped permanent breakpoint, stopped in "
6192 }
6193 }
6195 /* We come here if we hit a breakpoint but should not stop for it.
6196 Possibly we also were stepping and should stop for that. So fall
6197 through and test for stepping. But, if not stepping, do not
6198 stop. */
6200 /* In all-stop mode, if we're currently stepping but have stopped in
6201 some other thread, we need to switch back to the stepped thread. */
6206 {
6211 /* Having a step-resume breakpoint overrides anything
6212 else having to do with stepping commands until
6213 that breakpoint is reached. */
6216 }
6219 {
6222 /* Likewise if we aren't even stepping. */
6225 }
6227 /* Re-fetch current thread's frame in case the code above caused
6228 the frame cache to be re-initialized, making our FRAME variable
6229 a dangling pointer. */
6234 /* If stepping through a line, keep going if still within it.
6236 Note that step_range_end is the address of the first instruction
6237 beyond the step range, and NOT the address of the last instruction
6238 within it!
6240 Note also that during reverse execution, we may be stepping
6241 through a function epilogue and therefore must detect when
6242 the current-frame changes in the middle of a line. */
6249 {
6251 fprintf_unfiltered
6256 /* Tentatively re-enable range stepping; `resume' disables it if
6257 necessary (e.g., if we're stepping over a breakpoint or we
6258 have software watchpoints). */
6261 /* When stepping backward, stop at beginning of line range
6262 (unless it's the function entry point, in which case
6263 keep going back to the call point). */
6269 else
6273 }
6275 /* We stepped out of the stepping range. */
6277 /* If we are stepping at the source level and entered the runtime
6278 loader dynamic symbol resolution code...
6280 EXEC_FORWARD: we keep on single stepping until we exit the run
6281 time loader code and reach the callee's address.
6283 EXEC_REVERSE: we've already executed the callee (backward), and
6284 the runtime loader code is handled just like any other
6285 undebuggable function call. Now we need only keep stepping
6286 backward through the trampoline code, and that's handled further
6287 down, so there is nothing for us to do here. */
6292 {
6293 CORE_ADDR pc_after_resolver =
6302 {
6303 /* Set up a step-resume breakpoint at the address
6304 indicated by SKIP_SOLIB_RESOLVER. */
6305 symtab_and_line sr_sal;
6311 }
6315 }
6317 /* Step through an indirect branch thunk. */
6321 {
6327 }
6333 {
6337 /* The inferior, while doing a "step" or "next", has ended up in
6338 a signal trampoline (either by a signal being delivered or by
6339 the signal handler returning). Just single-step until the
6340 inferior leaves the trampoline (either by calling the handler
6341 or returning). */
6344 }
6346 /* If we're in the return path from a shared library trampoline,
6347 we want to proceed through the trampoline when stepping. */
6348 /* macro/2012-04-25: This needs to come before the subroutine
6349 call check below as on some targets return trampolines look
6350 like subroutine calls (MIPS16 return thunks). */
6355 {
6356 /* Determine where this trampoline returns. */
6358 CORE_ADDR real_stop_pc
6365 /* Only proceed through if we know where it's going. */
6367 {
6368 /* And put the step-breakpoint there and go until there. */
6369 symtab_and_line sr_sal;
6374 /* Do not specify what the fp should be when we stop since
6375 on some machines the prologue is where the new fp value
6376 is established. */
6380 /* Restart without fiddling with the step ranges or
6381 other state. */
6384 }
6385 }
6387 /* Check for subroutine calls. The check for the current frame
6388 equalling the step ID is not necessary - the check of the
6389 previous frame's ID is sufficient - but it is a common case and
6390 cheaper than checking the previous frame's ID.
6392 NOTE: frame_id_eq will never report two invalid frame IDs as
6393 being equal, so to get into this block, both the current and
6394 previous frame must have valid frame IDs. */
6395 /* The outer_frame_id check is a heuristic to detect stepping
6396 through startup code. If we step over an instruction which
6397 sets the stack pointer from an invalid value to a valid value,
6398 we may detect that as a subroutine call from the mythical
6399 "outermost" function. This could be fixed by marking
6400 outermost frames as !stack_p,code_p,special_p. Then the
6401 initial outermost frame, before sp was valid, would
6402 have code_addr == &_start. See the comment in frame_id_eq
6403 for more. */
6409 outer_frame_id)
6412 {
6414 CORE_ADDR real_stop_pc;
6420 {
6421 /* I presume that step_over_calls is only 0 when we're
6422 supposed to be stepping at the assembly language level
6423 ("stepi"). Just stop. */
6424 /* And this works the same backward as frontward. MVS */
6427 }
6429 /* Reverse stepping through solib trampolines. */
6436 {
6437 /* Any solib trampoline code can be handled in reverse
6438 by simply continuing to single-step. We have already
6439 executed the solib function (backwards), and a few
6440 steps will take us back through the trampoline to the
6441 caller. */
6444 }
6447 {
6448 /* We're doing a "next".
6450 Normal (forward) execution: set a breakpoint at the
6451 callee's return address (the address at which the caller
6452 will resume).
6454 Reverse (backward) execution. set the step-resume
6455 breakpoint at the start of the function that we just
6456 stepped into (backwards), and continue to there. When we
6457 get there, we'll need to single-step back to the caller. */
6460 {
6461 /* If we're already at the start of the function, we've either
6462 just stepped backward into a single instruction function,
6463 or stepped back out of a signal handler to the first instruction
6464 of the function. Just keep going, which will single-step back
6465 to the caller. */
6467 {
6468 /* Normal function call return (static or dynamic). */
6469 symtab_and_line sr_sal;
6474 }
6475 }
6476 else
6481 }
6483 /* If we are in a function call trampoline (a stub between the
6484 calling routine and the real function), locate the real
6485 function. That's what tells us (a) whether we want to step
6486 into it at all, and (b) what prologue we want to run to the
6487 end of, if we do step into it. */
6495 {
6496 symtab_and_line sr_sal;
6504 }
6506 /* If we have line number information for the function we are
6507 thinking of stepping into and the function isn't on the skip
6508 list, step into it.
6510 If there are several symtabs at that PC (e.g. with include
6511 files), just want to know whether *any* of them have line
6512 numbers. find_pc_line handles this. */
6513 {
6519 tmp_sal))
6520 {
6523 else
6526 }
6527 }
6529 /* If we have no line number and the step-stop-if-no-debug is
6530 set, we stop the step so that the user has a chance to switch
6531 in assembly mode. */
6534 {
6537 }
6540 {
6541 /* If we're already at the start of the function, we've either just
6542 stepped backward into a single instruction function without line
6543 number info, or stepped back out of a signal handler to the first
6544 instruction of the function without line number info. Just keep
6545 going, which will single-step back to the caller. */
6547 {
6548 /* Set a breakpoint at callee's start address.
6549 From there we can step once and be back in the caller. */
6550 symtab_and_line sr_sal;
6555 }
6556 }
6557 else
6558 /* Set a breakpoint at callee's return address (the address
6559 at which the caller will resume). */
6564 }
6566 /* Reverse stepping through solib trampolines. */
6570 {
6576 {
6577 /* Any solib trampoline code can be handled in reverse
6578 by simply continuing to single-step. We have already
6579 executed the solib function (backwards), and a few
6580 steps will take us back through the trampoline to the
6581 caller. */
6584 }
6586 {
6587 /* Stepped backward into the solib dynsym resolver.
6588 Set a breakpoint at its start and continue, then
6589 one more step will take us out. */
6590 symtab_and_line sr_sal;
6597 }
6598 }
6602 /* NOTE: tausq/2004-05-24: This if block used to be done before all
6603 the trampoline processing logic, however, there are some trampolines
6604 that have no names, so we should do trampoline handling first. */
6608 {
6613 /* The inferior just stepped into, or returned to, an
6614 undebuggable function (where there is no debugging information
6615 and no line number corresponding to the address where the
6616 inferior stopped). Since we want to skip this kind of code,
6617 we keep going until the inferior returns from this
6618 function - unless the user has asked us not to (via
6619 set step-mode) or we no longer know how to get back
6620 to the call site. */
6623 {
6624 /* If we have no line number and the step-stop-if-no-debug
6625 is set, we stop the step so that the user has a chance to
6626 switch in assembly mode. */
6629 }
6630 else
6631 {
6632 /* Set a breakpoint at callee's return address (the address
6633 at which the caller will resume). */
6637 }
6638 }
6641 {
6642 /* It is stepi or nexti. We always want to stop stepping after
6643 one instruction. */
6648 }
6651 {
6652 /* We have no line number information. That means to stop
6653 stepping (does this always happen right after one instruction,
6654 when we do "s" in a function with no line numbers,
6655 or can this happen as a result of a return or longjmp?). */
6660 }
6662 /* Look for "calls" to inlined functions, part one. If the inline
6663 frame machinery detected some skipped call sites, we have entered
6664 a new inline function. */
6669 {
6677 {
6678 /* For "step", we're going to stop. But if the call site
6679 for this inlined function is on the same source line as
6680 we were previously stepping, go down into the function
6681 first. Otherwise stop at the call site. */
6689 }
6690 else
6691 {
6692 /* For "next", we should stop at the call site if it is on a
6693 different source line. Otherwise continue through the
6694 inlined function. */
6698 else
6701 }
6702 }
6704 /* Look for "calls" to inlined functions, part two. If we are still
6705 in the same real function we were stepping through, but we have
6706 to go further up to find the exact frame ID, we are stepping
6707 through a more inlined call beyond its call site. */
6714 {
6721 else
6724 }
6729 {
6730 /* We are at the start of a different line. So stop. Note that
6731 we don't stop if we step into the middle of a different line.
6732 That is said to make things like for (;;) statements work
6733 better. */
6739 }
6741 /* We aren't done stepping.
6743 Optimize by setting the stepping range to the line.
6744 (We might not be in the original line, but if we entered a
6745 new line in mid-statement, we continue stepping. This makes
6746 things like for(;;) statements work better.) */
6756 }
6758 /* In all-stop mode, if we're currently stepping but have stopped in
6759 some other thread, we may need to switch back to the stepped
6760 thread. Returns true we set the inferior running, false if we left
6761 it stopped (and the event needs further processing). */
6763 static int
6765 {
6767 {
6770 /* If any thread is blocked on some internal breakpoint, and we
6771 simply need to step over that breakpoint to get it going
6772 again, do that first. */
6774 /* However, if we see an event for the stepping thread, then we
6775 know all other threads have been moved past their breakpoints
6776 already. Let the caller check whether the step is finished,
6777 etc., before deciding to move it past a breakpoint. */
6781 /* Check if the current thread is blocked on an incomplete
6782 step-over, interrupted by a random signal. */
6785 {
6787 {
6791 }
6794 }
6796 /* Check if the current thread is blocked by a single-step
6797 breakpoint of another thread. */
6799 {
6801 {
6803 "infrun: need to step [%s] over single-step "
6806 }
6809 }
6811 /* If this thread needs yet another step-over (e.g., stepping
6812 through a delay slot), do it first before moving on to
6813 another thread. */
6815 {
6817 {
6821 }
6824 }
6826 /* If scheduler locking applies even if not stepping, there's no
6827 need to walk over threads. Above we've checked whether the
6828 current thread is stepping. If some other thread not the
6829 event thread is stepping, then it must be that scheduler
6830 locking is not in effect. */
6834 /* Otherwise, we no longer expect a trap in the current thread.
6835 Clear the trap_expected flag before switching back -- this is
6836 what keep_going does as well, if we call it. */
6839 /* Likewise, clear the signal if it should not be passed. */
6843 /* Do all pending step-overs before actually proceeding with
6844 step/next/etc. */
6846 {
6849 }
6851 /* Look for the stepping/nexting thread. */
6855 {
6856 /* Ignore threads of processes the caller is not
6857 resuming. */
6862 /* When stepping over a breakpoint, we lock all threads
6863 except the one that needs to move past the breakpoint.
6864 If a non-event thread has this set, the "incomplete
6865 step-over" check above should have caught it earlier. */
6867 {
6869 "[%s] has inconsistent state: "
6873 }
6875 /* Did we find the stepping thread? */
6877 {
6878 /* Yep. There should only one though. */
6881 /* The event thread is handled at the top, before we
6882 enter this loop. */
6885 /* If some thread other than the event thread is
6886 stepping, then scheduler locking can't be in effect,
6887 otherwise we wouldn't have resumed the current event
6888 thread in the first place. */
6892 }
6893 }
6896 {
6902 {
6905 }
6906 }
6907 }
6910 }
6912 /* Set a previously stepped thread back to stepping. Returns true on
6913 success, false if the resume is not possible (e.g., the thread
6914 vanished). */
6916 static int
6918 {
6923 /* If the stepping thread exited, then don't try to switch back and
6924 resume it, which could fail in several different ways depending
6925 on the target. Instead, just keep going.
6927 We can find a stepping dead thread in the thread list in two
6928 cases:
6930 - The target supports thread exit events, and when the target
6931 tries to delete the thread from the thread list, inferior_ptid
6932 pointed at the exiting thread. In such case, calling
6933 delete_thread does not really remove the thread from the list;
6934 instead, the thread is left listed, with 'exited' state.
6936 - The target's debug interface does not support thread exit
6937 events, and so we have no idea whatsoever if the previously
6938 stepping thread is still alive. For that reason, we need to
6939 synchronously query the target now. */
6942 {
6945 "infrun: not resuming previously "
6950 }
6962 /* If the PC of the thread we were trying to single-step has
6963 changed, then that thread has trapped or been signaled, but the
6964 event has not been reported to GDB yet. Re-poll the target
6965 looking for this particular thread's event (i.e. temporarily
6966 enable schedlock) by:
6968 - setting a break at the current PC
6969 - resuming that particular thread, only (by setting trap
6970 expected)
6972 This prevents us continuously moving the single-step breakpoint
6973 forward, one instruction at a time, overstepping. */
6976 {
6977 ptid_t resume_ptid;
6985 /* Clear the info of the previous step-over, as it's no longer
6986 valid (if the thread was trying to step over a breakpoint, it
6987 has already succeeded). It's what keep_going would do too,
6988 if we called it. Do this before trying to insert the sss
6989 breakpoint, otherwise if we were previously trying to step
6990 over this exact address in another thread, the breakpoint is
6991 skipped. */
7002 }
7003 else
7004 {
7010 }
7012 }
7014 /* Is thread TP in the middle of (software or hardware)
7015 single-stepping? (Note the result of this function must never be
7016 passed directly as target_resume's STEP parameter.) */
7018 static int
7020 {
7026 }
7028 /* Inferior has stepped into a subroutine call with source code that
7029 we should not step over. Do step to the first line of code in
7030 it. */
7032 static void
7035 {
7038 compunit_symtab *cust
7041 ecs->stop_func_start
7045 /* Use the step_resume_break to step until the end of the prologue,
7046 even if that involves jumps (as it seems to on the vax under
7047 4.2). */
7048 /* If the prologue ends in the middle of a source line, continue to
7049 the end of that source line (if it is still within the function).
7050 Otherwise, just go to end of prologue. */
7056 /* Architectures which require breakpoint adjustment might not be able
7057 to place a breakpoint at the computed address. If so, the test
7058 ``ecs->stop_func_start == stop_pc'' will never succeed. Adjust
7059 ecs->stop_func_start to an address at which a breakpoint may be
7060 legitimately placed.
7062 Note: kevinb/2004-01-19: On FR-V, if this adjustment is not
7063 made, GDB will enter an infinite loop when stepping through
7064 optimized code consisting of VLIW instructions which contain
7065 subinstructions corresponding to different source lines. On
7066 FR-V, it's not permitted to place a breakpoint on any but the
7067 first subinstruction of a VLIW instruction. When a breakpoint is
7068 set, GDB will adjust the breakpoint address to the beginning of
7069 the VLIW instruction. Thus, we need to make the corresponding
7070 adjustment here when computing the stop address. */
7073 {
7074 ecs->stop_func_start
7077 }
7080 {
7081 /* We are already there: stop now. */
7084 }
7085 else
7086 {
7087 /* Put the step-breakpoint there and go until there. */
7088 symtab_and_line sr_sal;
7093 /* Do not specify what the fp should be when we stop since on
7094 some machines the prologue is where the new fp value is
7095 established. */
7098 /* And make sure stepping stops right away then. */
7101 }
7103 }
7105 /* Inferior has stepped backward into a subroutine call with source
7106 code that we should not step over. Do step to the beginning of the
7107 last line of code in it. */
7109 static void
7112 {
7120 ecs->stop_func_start
7125 /* OK, we're just going to keep stepping here. */
7127 {
7128 /* We're there already. Just stop stepping now. */
7130 }
7131 else
7132 {
7133 /* Else just reset the step range and keep going.
7134 No step-resume breakpoint, they don't work for
7135 epilogues, which can have multiple entry paths. */
7139 }
7141 }
7143 /* Insert a "step-resume breakpoint" at SR_SAL with frame ID SR_ID.
7144 This is used to both functions and to skip over code. */
7146 static void
7151 {
7152 /* There should never be more than one step-resume or longjmp-resume
7153 breakpoint per thread, so we should never be setting a new
7154 step_resume_breakpoint when one is already active. */
7165 }
7167 void
7171 {
7174 bp_step_resume);
7175 }
7177 /* Insert a "high-priority step-resume breakpoint" at RETURN_FRAME.pc.
7178 This is used to skip a potential signal handler.
7180 This is called with the interrupted function's frame. The signal
7181 handler, when it returns, will resume the interrupted function at
7182 RETURN_FRAME.pc. */
7184 static void
7186 {
7191 symtab_and_line sr_sal;
7198 bp_hp_step_resume);
7199 }
7201 /* Insert a "step-resume breakpoint" at the previous frame's PC. This
7202 is used to skip a function after stepping into it (for "next" or if
7203 the called function has no debugging information).
7205 The current function has almost always been reached by single
7206 stepping a call or return instruction. NEXT_FRAME belongs to the
7207 current function, and the breakpoint will be set at the caller's
7208 resume address.
7210 This is a separate function rather than reusing
7211 insert_hp_step_resume_breakpoint_at_frame in order to avoid
7212 get_prev_frame, which may stop prematurely (see the implementation
7213 of frame_unwind_caller_id for an example). */
7215 static void
7217 {
7218 /* We shouldn't have gotten here if we don't know where the call site
7219 is. */
7224 symtab_and_line sr_sal;
7232 }
7234 /* Insert a "longjmp-resume" breakpoint at PC. This is used to set a
7235 new breakpoint at the target of a jmp_buf. The handling of
7236 longjmp-resume uses the same mechanisms used for handling
7237 "step-resume" breakpoints. */
7239 static void
7241 {
7242 /* There should never be more than one longjmp-resume breakpoint per
7243 thread, so we should never be setting a new
7244 longjmp_resume_breakpoint when one is already active. */
7254 }
7256 /* Insert an exception resume breakpoint. TP is the thread throwing
7257 the exception. The block B is the block of the unwinder debug hook
7258 function. FRAME is the frame corresponding to the call to this
7259 function. SYM is the symbol of the function argument holding the
7260 target PC of the exception. */
7262 static void
7267 {
7268 try
7269 {
7272 CORE_ADDR handler;
7278 /* If the value was optimized out, revert to the old behavior. */
7280 {
7289 handler,
7292 /* set_momentary_breakpoint_at_pc invalidates FRAME. */
7297 }
7298 }
7300 {
7301 /* We want to ignore errors here. */
7302 }
7303 }
7305 /* A helper for check_exception_resume that sets an
7306 exception-breakpoint based on a SystemTap probe. */
7308 static void
7312 {
7314 CORE_ADDR handler;
7327 handler));
7333 }
7335 /* This is called when an exception has been intercepted. Check to
7336 see whether the exception's destination is of interest, and if so,
7337 set an exception resume breakpoint there. */
7339 static void
7342 {
7346 /* First see if this exception unwinding breakpoint was set via a
7347 SystemTap probe point. If so, the probe has two arguments: the
7348 CFA and the HANDLER. We ignore the CFA, extract the handler, and
7349 set a breakpoint there. */
7352 {
7355 }
7361 try
7362 {
7368 /* The exception breakpoint is a thread-specific breakpoint on
7369 the unwinder's debug hook, declared as:
7371 void _Unwind_DebugHook (void *cfa, void *handler);
7373 The CFA argument indicates the frame to which control is
7374 about to be transferred. HANDLER is the destination PC.
7376 We ignore the CFA and set a temporary breakpoint at HANDLER.
7377 This is not extremely efficient but it avoids issues in gdb
7378 with computing the DWARF CFA, and it also works even in weird
7379 cases such as throwing an exception from inside a signal
7380 handler. */
7384 {
7390 else
7391 {
7395 }
7396 }
7397 }
7399 {
7400 }
7401 }
7403 static void
7405 {
7409 /* Let callers know we don't want to wait for the inferior anymore. */
7412 /* If all-stop, but the target is always in non-stop mode, stop all
7413 threads now that we're presenting the stop to the user. */
7416 }
7418 /* Like keep_going, but passes the signal to the inferior, even if the
7419 signal is set to nopass. */
7421 static void
7423 {
7427 /* Save the pc before execution, to compare with pc after stop. */
7432 {
7437 "infrun: %s has trap_expected set, "
7441 /* We haven't yet gotten our trap, and either: intercepted a
7442 non-signal event (e.g., a fork); or took a signal which we
7443 are supposed to pass through to the inferior. Simply
7444 continue. */
7446 }
7448 {
7449 /* Another thread is stepping over a breakpoint in-line. If
7450 this thread needs a step-over too, queue the request. In
7451 either case, this resume must be deferred for later. */
7456 {
7459 "infrun: step-over already in progress: "
7463 }
7464 else
7465 {
7468 "infrun: step-over in progress: "
7471 }
7472 }
7473 else
7474 {
7478 step_over_what step_what;
7480 /* Either the trap was not expected, but we are continuing
7481 anyway (if we got a signal, the user asked it be passed to
7482 the child)
7483 -- or --
7484 We got our expected trap, but decided we should resume from
7485 it.
7487 We're going to run this baby now!
7489 Note that insert_breakpoints won't try to re-insert
7490 already inserted breakpoints. Therefore, we don't
7491 care if breakpoints were already inserted, or not. */
7493 /* If we need to step over a breakpoint, and we're not using
7494 displaced stepping to do so, insert all breakpoints
7495 (watchpoints, etc.) but the one we're stepping over, step one
7496 instruction, and then re-insert the breakpoint when that step
7497 is finished. */
7505 /* We can't use displaced stepping if we need to step past a
7506 watchpoint. The instruction copied to the scratch pad would
7507 still trigger the watchpoint. */
7510 {
7514 }
7518 /* If we now need to do an in-line step-over, we need to stop
7519 all other threads. Note this must be done before
7520 insert_breakpoints below, because that removes the breakpoint
7521 we're about to step over, otherwise other threads could miss
7522 it. */
7526 /* Stop stepping if inserting breakpoints fails. */
7527 try
7528 {
7530 }
7532 {
7537 }
7542 }
7545 }
7547 /* Called when we should continue running the inferior, because the
7548 current event doesn't cause a user visible stop. This does the
7549 resuming part; waiting for the next event is done elsewhere. */
7551 static void
7553 {
7561 }
7563 /* This function normally comes after a resume, before
7564 handle_inferior_event exits. It takes care of any last bits of
7565 housekeeping, and sets the all-important wait_some_more flag. */
7567 static void
7569 {
7577 }
7579 /* We are done with the step range of a step/next/si/ni command.
7580 Called once for each n of a "step n" operation. */
7582 static void
7584 {
7587 }
7589 /* Several print_*_reason functions to print why the inferior has stopped.
7590 We always print something when the inferior exits, or receives a signal.
7591 The rest of the cases are dealt with later on in normal_stop and
7592 print_it_typical. Ideally there should be a call to one of these
7593 print_*_reason functions functions from handle_inferior_event each time
7594 stop_waiting is called.
7596 Note that we don't call these directly, instead we delegate that to
7597 the interpreters, through observers. Interpreters then call these
7598 with whatever uiout is right. */
7600 void
7602 {
7603 /* For CLI-like interpreters, print nothing. */
7606 {
7609 }
7610 }
7612 void
7614 {
7617 uiout->field_string
7631 }
7633 void
7635 {
7641 {
7651 }
7652 else
7653 {
7655 uiout->field_string
7662 }
7663 }
7665 /* Some targets/architectures can do extra processing/display of
7666 segmentation faults. E.g., Intel MPX boundary faults.
7667 Call the architecture dependent function to handle the fault. */
7669 static void
7671 {
7677 }
7679 void
7681 {
7687 ;
7689 {
7697 {
7701 }
7702 }
7703 else
7708 else
7709 {
7713 uiout->field_string
7725 }
7727 }
7729 void
7731 {
7733 }
7735 /* Print current location without a level number, if we have changed
7736 functions or hit a breakpoint. Print source line if we have one.
7737 bpstat_print contains the logic deciding in detail what to print,
7738 based on the event(s) that just occurred. */
7740 static void
7742 {
7750 {
7752 /* FIXME: cagney/2002-12-01: Given that a frame ID does (or
7753 should) carry around the function and does (or should) use
7754 that when doing a frame comparison. */
7760 {
7761 /* Finished step, just print source line. */
7763 }
7764 else
7765 {
7766 /* Print location and source line. */
7768 }
7771 /* Print location and source line. */
7778 /* Something bogus. */
7784 }
7786 /* The behavior of this routine with respect to the source
7787 flag is:
7788 SRC_LINE: Print only source line
7789 LOCATION: Print only location
7790 SRC_AND_LOC: Print location and source line. */
7793 }
7795 /* See infrun.h. */
7797 void
7799 {
7801 ptid_t last_ptid;
7806 {
7811 /* Display the auto-display expressions. */
7814 }
7819 {
7825 }
7826 }
7828 /* See infrun.h. */
7830 void
7832 {
7834 {
7836 {
7841 }
7842 }
7843 }
7845 /* The execution context that just caused a normal stop. */
7847 struct stop_context
7848 {
7856 /* The stop ID. */
7857 ULONGEST stop_id;
7859 /* The event PTID. */
7861 ptid_t ptid;
7863 /* If stopp for a thread event, this is the thread that caused the
7864 stop. */
7867 /* The inferior that caused the stop. */
7869 };
7871 /* Initializes a new stop context. If stopped for a thread event, this
7872 takes a strong reference to the thread. */
7875 {
7881 {
7882 /* Take a strong reference so that the thread can't be deleted
7883 yet. */
7886 }
7887 else
7889 }
7891 /* Release a stop context previously created with save_stop_context.
7892 Releases the strong reference to the thread as well. */
7895 {
7898 }
7900 /* Return true if the current context no longer matches the saved stop
7901 context. */
7903 bool
7905 {
7915 }
7917 /* See infrun.h. */
7919 int
7921 {
7923 ptid_t last_ptid;
7929 /* If an exception is thrown from this point on, make sure to
7930 propagate GDB's knowledge of the executing state to the
7931 frontend/user running state. A QUIT is an easy exception to see
7932 here, so do this before any filtered output. */
7940 {
7941 /* On some targets, we may still have live threads in the
7942 inferior when we get a process exit event. E.g., for
7943 "checkpoint", when the current checkpoint/fork exits,
7944 linux-fork.c automatically switches to another fork from
7945 within target_mourn_inferior. */
7948 }
7952 /* As we're presenting a stop, and potentially removing breakpoints,
7953 update the thread list so we can tell whether there are threads
7954 running on the target. With target remote, for example, we can
7955 only learn about new threads when we explicitly update the thread
7956 list. Do this before notifying the interpreters about signal
7957 stops, end of stepping ranges, etc., so that the "new thread"
7958 output is emitted before e.g., "Program received signal FOO",
7959 instead of after. */
7965 /* As with the notification of thread events, we want to delay
7966 notifying the user that we've switched thread context until
7967 the inferior actually stops.
7969 There's no point in saying anything if the inferior has exited.
7970 Note that SIGNALLED here means "exited with a signal", not
7971 "received a signal".
7973 Also skip saying anything in non-stop mode. In that mode, as we
7974 don't want GDB to switch threads behind the user's back, to avoid
7975 races where the user is typing a command to apply to thread x,
7976 but GDB switches to thread y before the user finishes entering
7977 the command, fetch_inferior_event installs a cleanup to restore
7978 the current thread back to the thread the user had selected right
7979 after this event is handled, so we're not really switching, only
7980 informing of a stop. */
7983 && target_has_execution
7987 {
7989 {
7994 }
7996 }
7999 {
8002 {
8005 }
8006 }
8008 /* Note: this depends on the update_thread_list call above. */
8011 /* If an auto-display called a function and that got a signal,
8012 delete that auto-display to avoid an infinite recursion. */
8018 {
8020 }
8022 /* Let the user/frontend see the threads as stopped. */
8025 /* Select innermost stack frame - i.e., current frame is frame 0,
8026 and current location is based on that. Handle the case where the
8027 dummy call is returning after being stopped. E.g. the dummy call
8028 previously hit a breakpoint. (If the dummy call returns
8029 normally, we won't reach here.) Do this before the stop hook is
8030 run, so that it doesn't get to see the temporary dummy frame,
8031 which is not where we'll present the stop. */
8033 {
8035 {
8036 /* Pop the empty frame that contains the stack dummy. This
8037 also restores inferior state prior to the call (struct
8038 infcall_suspend_state). */
8043 /* frame_pop calls reinit_frame_cache as the last thing it
8044 does which means there's now no selected frame. */
8045 }
8049 /* Set the current source location. */
8051 }
8053 /* Look up the hook_stop and run it (CLI internally handles problem
8054 of stop_command's pre-hook not existing). */
8056 {
8057 stop_context saved_context;
8059 try
8060 {
8062 }
8064 {
8067 }
8069 /* If the stop hook resumes the target, then there's no point in
8070 trying to notify about the previous stop; its context is
8071 gone. Likewise if the command switches thread or inferior --
8072 the observers would print a stop for the wrong
8073 thread/inferior. */
8076 }
8078 /* Notify observers about the stop. This is where the interpreters
8079 print the stop event. */
8082 stop_print_frame);
8083 else
8089 {
8093 /* Delete the breakpoint we stopped at, if it wants to be deleted.
8094 Delete any breakpoint that is to be deleted at the next stop. */
8096 }
8098 /* Try to get rid of automatically added inferiors that are no
8099 longer needed. Keeping those around slows down things linearly.
8100 Note that this never removes the current inferior. */
8104 }
8105 \f
8106 int
8108 {
8110 }
8112 int
8114 {
8116 }
8118 int
8120 {
8122 }
8124 static void
8126 {
8128 {
8133 }
8139 }
8141 int
8143 {
8149 }
8151 int
8153 {
8159 }
8161 int
8163 {
8169 }
8171 /* Update the global 'signal_catch' from INFO and notify the
8172 target. */
8174 void
8176 {
8183 }
8185 static void
8187 {
8190 }
8192 static void
8194 {
8207 }
8209 /* Specify how various signals in the inferior should be handled. */
8211 static void
8213 {
8220 {
8222 }
8224 /* Allocate and zero an array of flags for which signals to handle. */
8229 /* Break the command line up into args. */
8233 /* Walk through the args, looking for signal oursigs, signal names, and
8234 actions. Signal numbers and signal names may be interspersed with
8235 actions, with the actions being performed for all signals cumulatively
8236 specified. Signal ranges can be specified as <LOW>-<HIGH>. */
8239 {
8242 {;
8243 }
8248 {
8249 /* Apply action to all signals except those used by the
8250 debugger. Silently skip those. */
8254 }
8256 {
8259 }
8261 {
8263 }
8265 {
8267 }
8269 {
8271 }
8273 {
8275 }
8277 {
8279 }
8281 {
8284 }
8286 {
8288 }
8290 {
8291 /* It is numeric. The numeric signal refers to our own
8292 internal signal numbering from target.h, not to host/target
8293 signal number. This is a feature; users really should be
8294 using symbolic names anyway, and the common ones like
8295 SIGHUP, SIGINT, SIGALRM, etc. will work right anyway. */
8300 {
8303 }
8305 {
8306 /* Bet he didn't figure we'd think of this case... */
8308 }
8309 }
8310 else
8311 {
8314 {
8316 }
8317 else
8318 {
8319 /* Not a number and not a recognized flag word => complain. */
8321 }
8322 }
8324 /* If any signal numbers or symbol names were found, set flags for
8325 which signals to apply actions to. */
8328 {
8330 {
8334 {
8338 {
8340 }
8341 else
8343 }
8348 /* Make sure that "all" doesn't print these. */
8353 }
8354 }
8355 }
8359 {
8365 {
8366 /* Show the results. */
8371 }
8374 }
8375 }
8377 /* Complete the "handle" command. */
8379 static void
8383 {
8385 {
8395 NULL,
8396 };
8400 }
8402 enum gdb_signal
8404 {
8409 }
8411 /* Print current contents of the tables set by the handle command.
8412 It is possible we should just be printing signals actually used
8413 by the current target (but for things to work right when switching
8414 targets, all signals should be in the signal tables). */
8416 static void
8418 {
8424 {
8425 /* First see if this is a symbol name. */
8428 {
8429 /* No, try numeric. */
8430 oursig =
8432 }
8435 }
8438 /* These ugly casts brought to you by the native VAX compiler. */
8442 {
8443 QUIT;
8448 }
8452 }
8454 /* The $_siginfo convenience variable is a bit special. We don't know
8455 for sure the type of the value until we actually have a chance to
8456 fetch the data. The type can change depending on gdbarch, so it is
8457 also dependent on which thread you have selected.
8459 1. making $_siginfo be an internalvar that creates a new value on
8460 access.
8462 2. making the value of $_siginfo be an lval_computed value. */
8464 /* This function implements the lval_computed support for reading a
8465 $_siginfo value. */
8467 static void
8469 {
8470 LONGEST transferred;
8472 /* If we can access registers, so can we access $_siginfo. Likewise
8473 vice versa. */
8476 transferred =
8478 NULL,
8485 }
8487 /* This function implements the lval_computed support for writing a
8488 $_siginfo value. */
8490 static void
8492 {
8493 LONGEST transferred;
8495 /* If we can access registers, so can we access $_siginfo. Likewise
8496 vice versa. */
8500 TARGET_OBJECT_SIGNAL_INFO,
8501 NULL,
8508 }
8511 {
8512 siginfo_value_read,
8513 siginfo_value_write
8514 };
8516 /* Return a new value with the correct type for the siginfo object of
8517 the current thread using architecture GDBARCH. Return a void value
8518 if there's no object available. */
8523 {
8527 {
8531 }
8534 }
8536 \f
8537 /* infcall_suspend_state contains state about the program itself like its
8538 registers and any signal it received when it last stopped.
8539 This state must be restored regardless of how the inferior function call
8540 ends (either successfully, or after it hits a breakpoint or signal)
8541 if the program is to properly continue where it left off. */
8543 class infcall_suspend_state
8544 {
8546 /* Capture state from GDBARCH, TP, and REGCACHE that must be restored
8547 once the inferior function call has finished. */
8553 {
8557 {
8565 {
8566 /* Errors ignored. */
8568 }
8569 }
8572 {
8575 }
8576 }
8578 /* Return a pointer to the stored register state. */
8581 {
8583 }
8585 /* Restores the stored state into GDBARCH, TP, and REGCACHE. */
8590 {
8594 {
8597 /* Errors ignored. */
8600 }
8602 /* The inferior can be gone if the user types "print exit(0)"
8603 (and perhaps other times). */
8605 /* NB: The register write goes through to the target. */
8607 }
8610 /* How the current thread stopped before the inferior function call was
8611 executed. */
8614 /* The registers before the inferior function call was executed. */
8617 /* Format of SIGINFO_DATA or NULL if it is not present. */
8620 /* The inferior format depends on SIGINFO_GDBARCH and it has a length of
8621 TYPE_LENGTH (gdbarch_get_siginfo_type ()). For different gdbarch the
8622 content would be invalid. */
8624 };
8626 infcall_suspend_state_up
8628 {
8633 infcall_suspend_state_up inf_state
8636 /* Having saved the current state, adjust the thread state, discarding
8637 any stop signal information. The stop signal is not useful when
8638 starting an inferior function call, and run_inferior_call will not use
8639 the signal due to its `proceed' call with GDB_SIGNAL_0. */
8643 }
8645 /* Restore inferior session state to INF_STATE. */
8647 void
8649 {
8656 }
8658 void
8660 {
8662 }
8664 readonly_detached_regcache *
8666 {
8668 }
8670 /* infcall_control_state contains state regarding gdb's control of the
8671 inferior itself like stepping control. It also contains session state like
8672 the user's currently selected frame. */
8674 struct infcall_control_state
8675 {
8679 /* Other fields: */
8683 /* ID if the selected frame when the inferior function call was made. */
8685 };
8687 /* Save all of the information associated with the inferior<==>gdb
8688 connection. */
8690 infcall_control_state_up
8692 {
8703 /* Save original bpstat chain to INF_STATUS; replace it in TP with copy of
8704 chain. If caller's caller is walking the chain, they'll be happier if we
8705 hand them back the original chain when restore_infcall_control_state is
8706 called. */
8709 /* Other fields: */
8716 }
8718 static void
8720 {
8723 /* If inf_status->selected_frame_id is NULL, there was no previously
8724 selected frame. */
8726 {
8729 }
8732 }
8734 /* Restore inferior session state to INF_STATUS. */
8736 void
8738 {
8749 /* Handle the bpstat_copy of the chain. */
8755 /* Other fields: */
8760 {
8761 /* The point of the try/catch is that if the stack is clobbered,
8762 walking the stack might encounter a garbage pointer and
8763 error() trying to dereference it. */
8764 try
8765 {
8767 }
8769 {
8772 /* Error in restoring the selected frame. Select the
8773 innermost frame. */
8775 }
8776 }
8779 }
8781 void
8783 {
8792 /* See save_infcall_control_state for info on stop_bpstat. */
8796 }
8797 \f
8798 /* See infrun.h. */
8800 void
8802 {
8805 }
8806 \f
8808 /* User interface for reverse debugging:
8809 Set exec-direction / show exec-direction commands
8810 (returns error unless target implements to_set_exec_direction method). */
8817 exec_forward,
8818 exec_reverse,
8819 NULL
8820 };
8822 static void
8825 {
8827 {
8832 }
8833 else
8834 {
8837 }
8838 }
8840 static void
8843 {
8855 }
8856 }
8858 static void
8861 {
8864 }
8866 /* Implementation of `siginfo' variable. */
8869 {
8870 siginfo_make_value,
8871 NULL,
8872 NULL
8873 };
8875 /* Callback for infrun's target events source. This is marked when a
8876 thread has a pending status to process. */
8878 static void
8880 {
8882 }
8884 void
8886 {
8889 /* Register extra event sources in the event loop. */
8890 infrun_async_inferior_event_token
8935 NULL,
8936 show_debug_infrun,
8944 NULL,
8945 show_debug_displaced,
8963 set_non_stop,
8964 show_non_stop,
8969 {
8974 }
8976 /* Signals caused by debugger's own actions should not be given to
8977 the program afterwards.
8979 Do not deliver GDB_SIGNAL_TRAP by default, except when the user
8980 explicitly specifies that it should be delivered to the target
8981 program. Typically, that would occur when a user is debugging a
8982 target monitor on a simulator: the target monitor sets a
8983 breakpoint; the simulator encounters this breakpoint and halts
8984 the simulation handing control to GDB; GDB, noting that the stop
8985 address doesn't map to any known breakpoint, returns control back
8986 to the simulator; the simulator then delivers the hardware
8987 equivalent of a GDB_SIGNAL_TRAP to the program being
8988 debugged. */
8992 /* Signals that are not errors should not normally enter the debugger. */
9012 /* These signals are used internally by user-level thread
9013 implementations. (See signal(5) on Solaris.) Like the above
9014 signals, a healthy program receives and handles them as part of
9015 its normal operation. */
9025 /* Update cached state. */
9035 set_stop_on_solib_events,
9036 show_stop_on_solib_events,
9040 follow_fork_mode_kind_names,
9049 NULL,
9050 show_follow_fork_mode_string,
9054 follow_exec_mode_names,
9073 NULL,
9074 show_follow_exec_mode_string,
9089 show_scheduler_mode,
9100 NULL,
9101 show_schedule_multiple,
9110 NULL,
9111 show_step_stop_if_no_debug,
9124 NULL,
9125 show_can_use_displaced_stepping,
9136 /* Set/show detach-on-fork: user-settable mode. */
9144 /* Set/show disable address space randomization mode. */
9157 /* ptid initializations */
9166 /* Explicitly create without lookup, since that tries to create a
9167 value with a void typed value, and when we get here, gdbarch
9168 isn't initialized yet. At this point, we're quite sure there
9169 isn't another convenience variable of the same name. */
9180 set_observer_mode,
9181 show_observer_mode,
9184 }