| blob | 9473d1f20f62fd35e77dce071c8fd82f9488aa87 |
1 /* Target-struct-independent code to start (run) and stop an inferior
2 process.
4 Copyright (C) 1986-2018 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>
71 /* Prototypes for local functions */
97 /* Asynchronous signal handler registered as event loop source for
98 when we have pending events ready to be passed to the core. */
101 /* Stores whether infrun_async was previously enabled or disabled.
102 Starts off as -1, indicating "never enabled/disabled". */
105 /* See infrun.h. */
107 void
109 {
111 {
117 enable);
121 else
123 }
124 }
126 /* See infrun.h. */
128 void
130 {
132 }
134 /* When set, stop the 'step' command if we enter a function which has
135 no line number information. The normal behavior is that we step
136 over such function. */
138 static void
141 {
143 }
145 /* proceed and normal_stop use this to notify the user when the
146 inferior stopped in a different thread than it had been running
147 in. */
151 /* If set (default for legacy reasons), when following a fork, GDB
152 will detach from one of the fork branches, child or parent.
153 Exactly which branch is detached depends on 'set follow-fork-mode'
154 setting. */
159 static void
162 {
164 }
167 static void
170 {
172 }
175 /* Support for disabling address space randomization. */
179 static void
182 {
187 value);
188 else
192 }
194 static void
197 {
202 }
204 /* User interface for non-stop mode. */
209 static void
212 {
214 {
217 }
220 }
222 static void
225 {
228 value);
229 }
231 /* "Observer mode" is somewhat like a more extreme version of
232 non-stop, in which all GDB operations that might affect the
233 target's execution have been disabled. */
238 static void
241 {
243 {
246 }
254 /* We can insert fast tracepoints in or out of observer mode,
255 but enable them if we're going into this mode. */
261 /* Going *into* observer mode we must force non-stop, then
262 going out we leave it that way. */
264 {
267 }
272 }
274 static void
277 {
279 }
281 /* This updates the value of observer mode based on changes in
282 permissions. Note that we are deliberately ignoring the values of
283 may-write-registers and may-write-memory, since the user may have
284 reason to enable these during a session, for instance to turn on a
285 debugging-related global. */
287 void
289 {
292 newval = (!may_insert_breakpoints
293 && !may_insert_tracepoints
294 && may_insert_fast_tracepoints
295 && !may_stop
298 /* Let the user know if things change. */
304 }
306 /* Tables of how to react to signals; the user sets them. */
312 /* Table of signals that are registered with "catch signal". A
313 non-zero entry indicates that the signal is caught by some "catch
314 signal" command. This has size GDB_SIGNAL_LAST, to accommodate all
315 signals. */
318 /* Table of signals that the target may silently handle.
319 This is automatically determined from the flags above,
320 and simply cached here. */
323 #define SET_SIGS(nsigs,sigs,flags) \
324 do { \
325 int signum = (nsigs); \
326 while (signum-- > 0) \
327 if ((sigs)[signum]) \
328 (flags)[signum] = 1; \
329 } while (0)
331 #define UNSET_SIGS(nsigs,sigs,flags) \
332 do { \
333 int signum = (nsigs); \
334 while (signum-- > 0) \
335 if ((sigs)[signum]) \
336 (flags)[signum] = 0; \
337 } while (0)
339 /* Update the target's copy of SIGNAL_PROGRAM. The sole purpose of
340 this function is to avoid exporting `signal_program'. */
342 void
344 {
346 }
348 /* Value to pass to target_resume() to cause all threads to resume. */
350 #define RESUME_ALL minus_one_ptid
352 /* Command list pointer for the "stop" placeholder. */
356 /* Nonzero if we want to give control to the user when we're notified
357 of shared library events by the dynamic linker. */
360 /* Enable or disable optional shared library event breakpoints
361 as appropriate when the above flag is changed. */
363 static void
366 {
368 }
370 static void
373 {
375 value);
376 }
378 /* Nonzero after stop if current stack frame should be printed. */
382 /* This is a cached copy of the pid/waitstatus of the last event
383 returned by target_wait()/deprecated_target_wait_hook(). This
384 information is returned by get_last_target_status(). */
394 follow_fork_mode_child,
395 follow_fork_mode_parent,
396 NULL
397 };
400 static void
403 {
407 value);
408 }
409 \f
411 /* Handle changes to the inferior list based on the type of fork,
412 which process is being followed, and whether the other process
413 should be detached. On entry inferior_ptid must be the ptid of
414 the fork parent. At return inferior_ptid is the ptid of the
415 followed inferior. */
417 static int
419 {
432 {
433 /* The parent stays blocked inside the vfork syscall until the
434 child execs or exits. If we don't let the child run, then
435 the parent stays blocked. If we're telling the parent to run
436 in the foreground, the user will not be able to ctrl-c to get
437 back the terminal, effectively hanging the debug session. */
442 /* FIXME output string > 80 columns. */
444 }
447 {
448 /* Detach new forked process? */
450 {
451 /* Before detaching from the child, remove all breakpoints
452 from it. If we forked, then this has already been taken
453 care of by infrun.c. If we vforked however, any
454 breakpoint inserted in the parent is visible in the
455 child, even those added while stopped in a vfork
456 catchpoint. This will remove the breakpoints from the
457 parent also, but they'll be reinserted below. */
459 {
460 /* Keep breakpoints list in sync. */
462 }
465 {
466 /* Ensure that we have a process ptid. */
474 }
475 }
476 else
477 {
480 /* Add process to GDB's tables. */
489 scoped_restore_current_pspace_and_thread restore_pspace_thread;
496 /* If this is a vfork child, then the address-space is
497 shared with the parent. */
499 {
503 /* The parent will be frozen until the child is done
504 with the shared region. Keep track of the
505 parent. */
510 }
511 else
512 {
519 /* Let the shared library layer (e.g., solib-svr4) learn
520 about this new process, relocate the cloned exec, pull
521 in shared libraries, and install the solib event
522 breakpoint. If a "cloned-VM" event was propagated
523 better throughout the core, this wouldn't be
524 required. */
526 }
527 }
530 {
535 /* If we detached from the child, then we have to be careful
536 to not insert breakpoints in the parent until the child
537 is done with the shared memory region. However, if we're
538 staying attached to the child, then we can and should
539 insert breakpoints, so that we can debug it. A
540 subsequent child exec or exit is enough to know when does
541 the child stops using the parent's address space. */
544 }
545 }
546 else
547 {
548 /* Follow the child. */
553 {
563 }
565 /* Add the new inferior first, so that the target_detach below
566 doesn't unpush the target. */
578 /* If we're vforking, we want to hold on to the parent until the
579 child exits or execs. At child exec or exit time we can
580 remove the old breakpoints from the parent and detach or
581 resume debugging it. Otherwise, detach the parent now; we'll
582 want to reuse it's program/address spaces, but we can't set
583 them to the child before removing breakpoints from the
584 parent, otherwise, the breakpoints module could decide to
585 remove breakpoints from the wrong process (since they'd be
586 assigned to the same address space). */
589 {
597 }
599 {
601 {
602 /* Ensure that we have a process ptid. */
610 }
613 }
615 /* Note that the detach above makes PARENT_INF dangling. */
617 /* Add the child thread to the appropriate lists, and switch to
618 this new thread, before cloning the program space, and
619 informing the solib layer about this new process. */
625 /* If this is a vfork child, then the address-space is shared
626 with the parent. If we detached from the parent, then we can
627 reuse the parent's program/address spaces. */
629 {
632 }
633 else
634 {
642 /* Let the shared library layer (e.g., solib-svr4) learn
643 about this new process, relocate the cloned exec, pull in
644 shared libraries, and install the solib event breakpoint.
645 If a "cloned-VM" event was propagated better throughout
646 the core, this wouldn't be required. */
648 }
649 }
652 }
654 /* Tell the target to follow the fork we're stopped at. Returns true
655 if the inferior should be resumed; false, if the target for some
656 reason decided it's best not to resume. */
658 static int
660 {
665 /* Copy user stepping state to the new inferior thread. FIXME: the
666 followed fork child thread should have a copy of most of the
667 parent thread structure's run control related fields, not just these.
668 Initialized to avoid "may be used uninitialized" warnings from gcc. */
677 {
678 ptid_t wait_ptid;
681 /* Get the last target status returned by target_wait(). */
684 /* If not stopped at a fork event, then there's nothing else to
685 do. */
690 /* Check if we switched over from WAIT_PTID, since the event was
691 reported. */
694 {
695 /* We did. Switch back to WAIT_PTID thread, to tell the
696 target to follow it (in either direction). We'll
697 afterwards refuse to resume, and inform the user what
698 happened. */
699 thread_info *wait_thread
703 }
704 }
708 /* If there were any forks/vforks that were caught and are now to be
709 followed, then do so now. */
711 {
714 {
717 /* If the user did a next/step, etc, over a fork call,
718 preserve the stepping state in the fork child. */
720 {
721 step_resume_breakpoint = clone_momentary_breakpoint
726 exception_resume_breakpoint
730 /* For now, delete the parent's sr breakpoint, otherwise,
731 parent/child sr breakpoints are considered duplicates,
732 and the child version will not be installed. Remove
733 this when the breakpoints module becomes aware of
734 inferiors and address spaces. */
741 }
746 /* Set up inferior(s) as specified by the caller, and tell the
747 target to do whatever is necessary to follow either parent
748 or child. */
750 {
751 /* Target refused to follow, or there's some other reason
752 we shouldn't resume. */
754 }
755 else
756 {
757 /* This pending follow fork event is now handled, one way
758 or another. The previous selected thread may be gone
759 from the lists by now, but if it is still around, need
760 to clear the pending follow request. */
765 /* This makes sure we don't try to apply the "Switched
766 over from WAIT_PID" logic above. */
769 /* If we followed the child, switch to it... */
771 {
775 /* ... and preserve the stepping state, in case the
776 user was stepping over the fork call. */
778 {
788 }
789 else
790 {
791 /* If we get here, it was because we're trying to
792 resume from a fork catchpoint, but, the user
793 has switched threads away from the thread that
794 forked. In that case, the resume command
795 issued is most likely not applicable to the
796 child, so just warn, and refuse to resume. */
799 }
801 /* Reset breakpoints in the child as appropriate. */
803 }
804 }
805 }
808 /* Nothing to follow. */
815 }
818 }
820 static void
822 {
825 /* Was there a step_resume breakpoint? (There was if the user
826 did a "next" at the fork() call.) If so, explicitly reset its
827 thread number. Cloned step_resume breakpoints are disabled on
828 creation, so enable it here now that it is associated with the
829 correct thread.
831 step_resumes are a form of bp that are made to be per-thread.
832 Since we created the step_resume bp when the parent process
833 was being debugged, and now are switching to the child process,
834 from the breakpoint package's viewpoint, that's a switch of
835 "threads". We must update the bp's notion of which thread
836 it is for, or it'll be ignored when it triggers. */
839 {
842 }
844 /* Treat exception_resume breakpoints like step_resume breakpoints. */
846 {
849 }
851 /* Reinsert all breakpoints in the child. The user may have set
852 breakpoints after catching the fork, in which case those
853 were never set in the child, but only in the parent. This makes
854 sure the inserted breakpoints match the breakpoint list. */
858 }
860 /* The child has exited or execed: resume threads of the parent the
861 user wanted to be executing. */
863 static int
866 {
874 {
883 }
886 }
888 /* Save/restore inferior_ptid, current program space and current
889 inferior. Only use this if the current context points at an exited
890 inferior (and therefore there's no current thread to save). */
891 class scoped_restore_exited_inferior
892 {
896 {}
900 scoped_restore_current_program_space m_pspace;
901 scoped_restore_current_inferior m_inferior;
902 };
904 /* Called whenever we notice an exec or exit event, to handle
905 detaching or resuming a vfork parent. */
907 static void
909 {
913 {
916 /* This exec or exit marks the end of the shared memory region
917 between the parent and the child. If the user wanted to
918 detach from the parent, now is the time. */
921 {
926 /* follow-fork child, detach-on-fork on. */
931 maybe_restore_inferior;
933 maybe_restore_thread;
935 /* If we're handling a child exit, then inferior_ptid points
936 at the inferior's pid, not to a thread. */
939 else
942 /* We're letting loose of the parent. */
946 /* We're about to detach from the parent, which implicitly
947 removes breakpoints from its address space. There's a
948 catch here: we want to reuse the spaces for the child,
949 but, parent/child are still sharing the pspace at this
950 point, although the exec in reality makes the kernel give
951 the child a fresh set of new pages. The problem here is
952 that the breakpoints module being unaware of this, would
953 likely chose the child process to write to the parent
954 address space. Swapping the child temporarily away from
955 the spaces has the desired effect. Yes, this is "sort
956 of" a hack. */
964 {
971 {
975 }
976 else
977 {
981 }
982 }
986 /* Put it back. */
989 }
991 {
992 /* We're staying attached to the parent, so, really give the
993 child a new address space. */
1001 /* Break the bonds. */
1003 }
1004 else
1005 {
1008 /* If this is a vfork child exiting, then the pspace and
1009 aspaces were shared with the parent. Since we're
1010 reporting the process exit, we'll be mourning all that is
1011 found in the address space, and switching to null_ptid,
1012 preparing to start a new inferior. But, since we don't
1013 want to clobber the parent's address/program spaces, we
1014 go ahead and create a new one for this exiting
1015 inferior. */
1017 /* Switch to null_ptid while running clone_program_space, so
1018 that clone_program_space doesn't want to read the
1019 selected frame of a dead process. */
1020 scoped_restore restore_ptid
1023 /* This inferior is dead, so avoid giving the breakpoints
1024 module the option to write through to it (cloning a
1025 program space resets breakpoints). */
1037 /* Break the bonds. */
1039 }
1046 {
1047 /* If the user wanted the parent to be running, let it go
1048 free now. */
1049 scoped_restore_current_thread restore_thread;
1054 resume_parent);
1057 }
1058 }
1059 }
1061 /* Enum strings for "set|show follow-exec-mode". */
1066 {
1067 follow_exec_mode_new,
1068 follow_exec_mode_same,
1069 NULL,
1070 };
1073 static void
1076 {
1078 }
1080 /* EXEC_FILE_TARGET is assumed to be non-NULL. */
1082 static void
1084 {
1088 ptid_t process_ptid;
1090 /* This is an exec event that we actually wish to pay attention to.
1091 Refresh our symbol table to the newly exec'd program, remove any
1092 momentary bp's, etc.
1094 If there are breakpoints, they aren't really inserted now,
1095 since the exec() transformed our inferior into a fresh set
1096 of instructions.
1098 We want to preserve symbolic breakpoints on the list, since
1099 we have hopes that they can be reset after the new a.out's
1100 symbol table is read.
1102 However, any "raw" breakpoints must be removed from the list
1103 (e.g., the solib bp's), since their address is probably invalid
1104 now.
1106 And, we DON'T want to call delete_breakpoints() here, since
1107 that may write the bp's "shadow contents" (the instruction
1108 value that was overwritten witha TRAP instruction). Since
1109 we now have a new a.out, those shadow contents aren't valid. */
1113 /* The target reports the exec event to the main thread, even if
1114 some other thread does the exec, and even if the main thread was
1115 stopped or already gone. We may still have non-leader threads of
1116 the process on our list. E.g., on targets that don't have thread
1117 exit events (like remote); or on native Linux in non-stop mode if
1118 there were only two threads in the inferior and the non-leader
1119 one is the one that execs (and nothing forces an update of the
1120 thread list up to here). When debugging remotely, it's best to
1121 avoid extra traffic, when possible, so avoid syncing the thread
1122 list with the target, and instead go ahead and delete all threads
1123 of the process but one that reported the event. Note this must
1124 be done before calling update_breakpoints_after_exec, as
1125 otherwise clearing the threads' resources would reference stale
1126 thread breakpoints -- it may have been one of these threads that
1127 stepped across the exec. We could just clear their stepping
1128 states, but as long as we're iterating, might as well delete
1129 them. Deleting them now rather than at the next user-visible
1130 stop provides a nicer sequence of events for user and MI
1131 notifications. */
1136 /* We also need to clear any left over stale state for the
1137 leader/event thread. E.g., if there was any step-resume
1138 breakpoint or similar, it's gone now. We cannot truly
1139 step-to-next statement through an exec(). */
1147 /* The user may have had the main thread held stopped in the
1148 previous image (e.g., schedlock on, or non-stop). Release
1149 it now. */
1154 /* What is this a.out's name? */
1158 exec_file_target);
1160 /* We've followed the inferior through an exec. Therefore, the
1161 inferior has essentially been killed & reborn. */
1170 /* If we were unable to map the executable target pathname onto a host
1171 pathname, tell the user that. Otherwise GDB's subsequent behavior
1172 is confusing. Maybe it would even be better to stop at this point
1173 so that the user can specify a file manually before continuing. */
1177 exec_file_target);
1179 /* Reset the shared library package. This ensures that we get a
1180 shlib event when the child reaches "_start", at which point the
1181 dld will have had a chance to initialize the child. */
1182 /* Also, loading a symbol file below may trigger symbol lookups, and
1183 we don't want those to be satisfied by the libraries of the
1184 previous incarnation of this process. */
1188 {
1189 /* The user wants to keep the old inferior and program spaces
1190 around. Create a new fresh one, and switch to it. */
1192 /* Do exit processing for the original inferior before setting the new
1193 inferior's pid. Having two inferiors with the same pid would confuse
1194 find_inferior_p(t)id. Transfer the terminal state and info from the
1195 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. */
1234 /* The add_thread call ends up reading registers, so do it after updating the
1235 target description. */
1245 /* Reinsert all breakpoints. (Those which were symbolic have
1246 been reset to the proper address in the new a.out, thanks
1247 to symbol_file_command...). */
1250 /* The next resume of this inferior should bring it to the shlib
1251 startup breakpoints. (If the user had also set bp's on
1252 "main" from the old (parent) process, then they'll auto-
1253 matically get reset there in the new process.). */
1254 }
1256 /* The queue of threads that need to do a step-over operation to get
1257 past e.g., a breakpoint. What technique is used to step over the
1258 breakpoint/watchpoint does not matter -- all threads end up in the
1259 same queue, to maintain rough temporal order of execution, in order
1260 to avoid starvation, otherwise, we could e.g., find ourselves
1261 constantly stepping the same couple threads past their breakpoints
1262 over and over, if the single-step finish fast enough. */
1265 /* Bit flags indicating what the thread needs to step over. */
1267 enum step_over_what_flag
1268 {
1269 /* Step over a breakpoint. */
1272 /* Step past a non-continuable watchpoint, in order to let the
1273 instruction execute so we can evaluate the watchpoint
1274 expression. */
1276 };
1279 /* Info about an instruction that is being stepped over. */
1281 struct step_over_info
1282 {
1283 /* If we're stepping past a breakpoint, this is the address space
1284 and address of the instruction the breakpoint is set at. We'll
1285 skip inserting all breakpoints here. Valid iff ASPACE is
1286 non-NULL. */
1288 CORE_ADDR address;
1290 /* The instruction being stepped over triggers a nonsteppable
1291 watchpoint. If true, we'll skip inserting watchpoints. */
1294 /* The thread's global number. */
1296 };
1298 /* The step-over info of the location that is being stepped over.
1300 Note that with async/breakpoint always-inserted mode, a user might
1301 set a new breakpoint/watchpoint/etc. exactly while a breakpoint is
1302 being stepped over. As setting a new breakpoint inserts all
1303 breakpoints, we need to make sure the breakpoint being stepped over
1304 isn't inserted then. We do that by only clearing the step-over
1305 info when the step-over is actually finished (or aborted).
1307 Presently GDB can only step over one breakpoint at any given time.
1308 Given threads that can't run code in the same address space as the
1309 breakpoint's can't really miss the breakpoint, GDB could be taught
1310 to step-over at most one breakpoint per address space (so this info
1311 could move to the address space object if/when GDB is extended).
1312 The set of breakpoints being stepped over will normally be much
1313 smaller than the set of all breakpoints, so a flag in the
1314 breakpoint location structure would be wasteful. A separate list
1315 also saves complexity and run-time, as otherwise we'd have to go
1316 through all breakpoint locations clearing their flag whenever we
1317 start a new sequence. Similar considerations weigh against storing
1318 this info in the thread object. Plus, not all step overs actually
1319 have breakpoint locations -- e.g., stepping past a single-step
1320 breakpoint, or stepping to complete a non-continuable
1321 watchpoint. */
1324 /* Record the address of the breakpoint/instruction we're currently
1325 stepping over.
1326 N.B. We record the aspace and address now, instead of say just the thread,
1327 because when we need the info later the thread may be running. */
1329 static void
1333 {
1338 }
1340 /* Called when we're not longer stepping over a breakpoint / an
1341 instruction, so all breakpoints are free to be (re)inserted. */
1343 static void
1345 {
1353 }
1355 /* See infrun.h. */
1357 int
1359 CORE_ADDR address)
1360 {
1365 }
1367 /* See infrun.h. */
1369 int
1371 {
1374 }
1376 /* See infrun.h. */
1378 int
1380 {
1382 }
1384 /* Returns true if step-over info is valid. */
1386 static int
1388 {
1391 }
1393 \f
1394 /* Displaced stepping. */
1396 /* In non-stop debugging mode, we must take special care to manage
1397 breakpoints properly; in particular, the traditional strategy for
1398 stepping a thread past a breakpoint it has hit is unsuitable.
1399 'Displaced stepping' is a tactic for stepping one thread past a
1400 breakpoint it has hit while ensuring that other threads running
1401 concurrently will hit the breakpoint as they should.
1403 The traditional way to step a thread T off a breakpoint in a
1404 multi-threaded program in all-stop mode is as follows:
1406 a0) Initially, all threads are stopped, and breakpoints are not
1407 inserted.
1408 a1) We single-step T, leaving breakpoints uninserted.
1409 a2) We insert breakpoints, and resume all threads.
1411 In non-stop debugging, however, this strategy is unsuitable: we
1412 don't want to have to stop all threads in the system in order to
1413 continue or step T past a breakpoint. Instead, we use displaced
1414 stepping:
1416 n0) Initially, T is stopped, other threads are running, and
1417 breakpoints are inserted.
1418 n1) We copy the instruction "under" the breakpoint to a separate
1419 location, outside the main code stream, making any adjustments
1420 to the instruction, register, and memory state as directed by
1421 T's architecture.
1422 n2) We single-step T over the instruction at its new location.
1423 n3) We adjust the resulting register and memory state as directed
1424 by T's architecture. This includes resetting T's PC to point
1425 back into the main instruction stream.
1426 n4) We resume T.
1428 This approach depends on the following gdbarch methods:
1430 - gdbarch_max_insn_length and gdbarch_displaced_step_location
1431 indicate where to copy the instruction, and how much space must
1432 be reserved there. We use these in step n1.
1434 - gdbarch_displaced_step_copy_insn copies a instruction to a new
1435 address, and makes any necessary adjustments to the instruction,
1436 register contents, and memory. We use this in step n1.
1438 - gdbarch_displaced_step_fixup adjusts registers and memory after
1439 we have successfuly single-stepped the instruction, to yield the
1440 same effect the instruction would have had if we had executed it
1441 at its original address. We use this in step n3.
1443 The gdbarch_displaced_step_copy_insn and
1444 gdbarch_displaced_step_fixup functions must be written so that
1445 copying an instruction with gdbarch_displaced_step_copy_insn,
1446 single-stepping across the copied instruction, and then applying
1447 gdbarch_displaced_insn_fixup should have the same effects on the
1448 thread's memory and registers as stepping the instruction in place
1449 would have. Exactly which responsibilities fall to the copy and
1450 which fall to the fixup is up to the author of those functions.
1452 See the comments in gdbarch.sh for details.
1454 Note that displaced stepping and software single-step cannot
1455 currently be used in combination, although with some care I think
1456 they could be made to. Software single-step works by placing
1457 breakpoints on all possible subsequent instructions; if the
1458 displaced instruction is a PC-relative jump, those breakpoints
1459 could fall in very strange places --- on pages that aren't
1460 executable, or at addresses that are not proper instruction
1461 boundaries. (We do generally let other threads run while we wait
1462 to hit the software single-step breakpoint, and they might
1463 encounter such a corrupted instruction.) One way to work around
1464 this would be to have gdbarch_displaced_step_copy_insn fully
1465 simulate the effect of PC-relative instructions (and return NULL)
1466 on architectures that use software single-stepping.
1468 In non-stop mode, we can have independent and simultaneous step
1469 requests, so more than one thread may need to simultaneously step
1470 over a breakpoint. The current implementation assumes there is
1471 only one scratch space per process. In this case, we have to
1472 serialize access to the scratch space. If thread A wants to step
1473 over a breakpoint, but we are currently waiting for some other
1474 thread to complete a displaced step, we leave thread A stopped and
1475 place it in the displaced_step_request_queue. Whenever a displaced
1476 step finishes, we pick the next thread in the queue and start a new
1477 displaced step operation on it. See displaced_step_prepare and
1478 displaced_step_fixup for details. */
1480 /* Default destructor for displaced_step_closure. */
1484 /* Per-inferior displaced stepping state. */
1485 struct displaced_step_inferior_state
1486 {
1487 /* Pointer to next in linked list. */
1490 /* The process this displaced step state refers to. */
1493 /* True if preparing a displaced step ever failed. If so, we won't
1494 try displaced stepping for this inferior again. */
1497 /* If this is not nullptr, this is the thread carrying out a
1498 displaced single-step in process PID. This thread's state will
1499 require fixing up once it has completed its step. */
1502 /* The architecture the thread had when we stepped it. */
1505 /* The closure provided gdbarch_displaced_step_copy_insn, to be used
1506 for post-step cleanup. */
1509 /* The address of the original instruction, and the copy we
1510 made. */
1513 /* Saved contents of copy area. */
1515 };
1517 /* The list of states of processes involved in displaced stepping
1518 presently. */
1521 /* Get the displaced stepping state of process PID. */
1525 {
1535 }
1537 /* Returns true if any inferior has a thread doing a displaced
1538 step. */
1540 static int
1542 {
1552 }
1554 /* Return true if thread represented by PTID is doing a displaced
1555 step. */
1557 static int
1559 {
1567 }
1569 /* Return true if process PID has a thread doing a displaced step. */
1571 static int
1573 {
1581 }
1583 /* Add a new displaced stepping state for process PID to the displaced
1584 stepping state list, or return a pointer to an already existing
1585 entry, if it already exists. Never returns NULL. */
1589 {
1604 }
1606 /* If inferior is in displaced stepping, and ADDR equals to starting address
1607 of copy area, return corresponding displaced_step_closure. Otherwise,
1608 return NULL. */
1612 {
1616 /* If checking the mode of displaced instruction in copy area. */
1623 }
1625 /* Remove the displaced stepping state of process PID. */
1627 static void
1629 {
1637 {
1639 {
1643 }
1647 }
1648 }
1650 static void
1652 {
1654 }
1656 /* If ON, and the architecture supports it, GDB will use displaced
1657 stepping to step over breakpoints. If OFF, or if the architecture
1658 doesn't support it, GDB will instead use the traditional
1659 hold-and-step approach. If AUTO (which is the default), GDB will
1660 decide which technique to use to step over breakpoints depending on
1661 which of all-stop or non-stop mode is active --- displaced stepping
1662 in non-stop mode; hold-and-step in all-stop mode. */
1666 static void
1670 {
1676 else
1680 }
1682 /* Return non-zero if displaced stepping can/should be used to step
1683 over breakpoints of thread TP. */
1685 static int
1687 {
1701 }
1703 /* Clean out any stray displaced stepping state. */
1704 static void
1706 {
1707 /* Indicate that there is no cleanup pending. */
1712 }
1714 static void
1716 {
1721 }
1723 /* Dump LEN bytes at BUF in hex to FILE, followed by a newline. */
1724 void
1728 {
1734 }
1736 /* Prepare to single-step, using displaced stepping.
1738 Note that we cannot use displaced stepping when we have a signal to
1739 deliver. If we have a signal to deliver and an instruction to step
1740 over, then after the step, there will be no indication from the
1741 target whether the thread entered a signal handler or ignored the
1742 signal and stepped over the instruction successfully --- both cases
1743 result in a simple SIGTRAP. In the first case we mustn't do a
1744 fixup, and in the second case we must --- but we can't tell which.
1745 Comments in the code for 'random signals' in handle_inferior_event
1746 explain how we handle this case instead.
1748 Returns 1 if preparing was successful -- this thread is going to be
1749 stepped now; 0 if displaced stepping this thread got queued; or -1
1750 if this instruction can't be displaced stepped. */
1752 static int
1754 {
1760 ULONGEST len;
1765 /* We should never reach this function if the architecture does not
1766 support displaced stepping. */
1769 /* Nor if the thread isn't meant to step over a breakpoint. */
1772 /* Disable range stepping while executing in the scratch pad. We
1773 want a single-step even if executing the displaced instruction in
1774 the scratch buffer lands within the stepping range (e.g., a
1775 jump/branch). */
1778 /* We have to displaced step one thread at a time, as we only have
1779 access to a single scratch space per inferior. */
1784 {
1785 /* Already waiting for a displaced step to finish. Defer this
1786 request and place in queue. */
1795 }
1796 else
1797 {
1802 }
1806 scoped_restore_current_thread restore_thread;
1816 {
1817 /* There's a breakpoint set in the scratch pad location range
1818 (which is usually around the entry point). We'd either
1819 install it before resuming, which would overwrite/corrupt the
1820 scratch pad, or if it was already inserted, this displaced
1821 step would overwrite it. The latter is OK in the sense that
1822 we already assume that no thread is going to execute the code
1823 in the scratch pad range (after initial startup) anyway, but
1824 the former is unacceptable. Simply punt and fallback to
1825 stepping over this breakpoint in-line. */
1827 {
1829 "displaced: breakpoint set in scratch pad. "
1831 }
1834 }
1836 /* Save the original contents of the copy area. */
1847 {
1852 len);
1853 };
1858 {
1859 /* The architecture doesn't know how or want to displaced step
1860 this instruction or instruction sequence. Fallback to
1861 stepping over the breakpoint in-line. */
1864 }
1866 /* Save the information we need to fix things up if the step
1867 succeeds. */
1876 /* Resume execution at the copy. */
1886 }
1888 /* Wrapper for displaced_step_prepare_throw that disabled further
1889 attempts at displaced stepping if we get a memory error. */
1891 static int
1893 {
1896 TRY
1897 {
1899 }
1901 {
1909 {
1913 }
1915 /* Be verbose if "set displaced-stepping" is "on", silent if
1916 "auto". */
1918 {
1921 }
1923 /* Disable further displaced stepping attempts. */
1924 displaced_state
1927 }
1928 END_CATCH
1931 }
1933 static void
1936 {
1941 }
1943 /* Restore the contents of the copy area for thread PTID. */
1945 static void
1947 ptid_t ptid)
1948 {
1958 }
1960 /* If we displaced stepped an instruction successfully, adjust
1961 registers and memory to yield the same effect the instruction would
1962 have had if we had executed it at its original address, and return
1963 1. If the instruction didn't complete, relocate the PC and return
1964 -1. If the thread wasn't displaced stepping, return 0. */
1966 static int
1968 {
1974 /* Was any thread of this process doing a displaced step? */
1978 /* Was this event for the thread we displaced? */
1986 /* Fixup may need to read memory/registers. Switch to the thread
1987 that we're fixing up. Also, target_stopped_by_watchpoint checks
1988 the current thread. */
1991 /* Did the instruction complete successfully? */
1996 {
1997 /* Fix up the resulting state. */
2004 }
2005 else
2006 {
2007 /* Since the instruction didn't complete, all we can do is
2008 relocate the PC. */
2015 }
2022 }
2024 /* Data to be passed around while handling an event. This data is
2025 discarded between events. */
2026 struct execution_control_state
2027 {
2028 ptid_t ptid;
2029 /* The thread that got the event, if this was a thread event; NULL
2030 otherwise. */
2035 CORE_ADDR stop_func_start;
2036 CORE_ADDR stop_func_end;
2040 /* True if the event thread hit the single-step breakpoint of
2041 another thread. Thus the event doesn't cause a stop, the thread
2042 needs to be single-stepped past the single-step breakpoint before
2043 we can switch back to the original stepping thread. */
2045 };
2047 /* Clear ECS and set it to point at TP. */
2049 static void
2051 {
2055 }
2062 /* Are there any pending step-over requests? If so, run all we can
2063 now and return true. Otherwise, return false. */
2065 static int
2067 {
2070 /* Don't start a new step-over if we already have an in-line
2071 step-over operation ongoing. */
2076 {
2079 step_over_what step_what;
2086 /* If this inferior already has a displaced step in process,
2087 don't start a new one. */
2096 /* We currently stop all threads of all processes to step-over
2097 in-line. If we need to start a new in-line step-over, let
2098 any pending displaced steps finish first. */
2105 {
2109 }
2114 {
2116 "[%s] has inconsistent state: "
2122 }
2129 /* keep_going_pass_signal skips the step-over if the breakpoint
2130 is no longer inserted. In all-stop, we want to keep looking
2131 for a thread that needs a step-over instead of resuming TP,
2132 because we wouldn't be able to resume anything else until the
2133 target stops again. In non-stop, the resume always resumes
2134 only TP, so it's OK to let the thread resume freely. */
2147 /* If we started a new in-line step-over, we're done. */
2149 {
2152 }
2155 {
2156 /* On all-stop, shouldn't have resumed unless we needed a
2157 step over. */
2161 /* With remote targets (at least), in all-stop, we can't
2162 issue any further remote commands until the program stops
2163 again. */
2165 }
2167 /* Either the thread no longer needed a step-over, or a new
2168 displaced stepping sequence started. Even in the latter
2169 case, continue looking. Maybe we can also start another
2170 displaced step on a thread of other process. */
2171 }
2174 }
2176 /* Update global variables holding ptids to hold NEW_PTID if they were
2177 holding OLD_PTID. */
2178 static void
2180 {
2183 }
2185 \f
2192 schedlock_off,
2193 schedlock_on,
2194 schedlock_step,
2195 schedlock_replay,
2196 NULL
2197 };
2199 static void
2202 {
2206 value);
2207 }
2209 static void
2211 {
2213 {
2216 }
2217 }
2219 /* True if execution commands resume all threads of all processes by
2220 default; otherwise, resume only threads of the current inferior
2221 process. */
2224 /* Try to setup for software single stepping over the specified location.
2225 Return 1 if target_resume() should use hardware single step.
2227 GDBARCH the current gdbarch.
2228 PC the location to step over. */
2230 static int
2232 {
2240 }
2242 /* See infrun.h. */
2244 ptid_t
2246 {
2247 ptid_t resume_ptid;
2250 {
2251 /* With non-stop mode on, threads are always handled
2252 individually. */
2254 }
2257 {
2258 /* User-settable 'scheduler' mode requires solo thread
2259 resume. */
2261 }
2264 {
2265 /* User-settable 'scheduler' mode requires solo thread resume in replay
2266 mode. */
2268 }
2270 {
2271 /* Resume all threads of the current process (and none of other
2272 processes). */
2274 }
2275 else
2276 {
2277 /* Resume all threads of all processes. */
2279 }
2282 }
2284 /* Return a ptid representing the set of threads that we will resume,
2285 in the perspective of the target, assuming run control handling
2286 does not require leaving some threads stopped (e.g., stepping past
2287 breakpoint). USER_STEP indicates whether we're about to start the
2288 target for a stepping command. */
2290 static ptid_t
2292 {
2293 /* In non-stop, we always control threads individually. Note that
2294 the target may always work in non-stop mode even with "set
2295 non-stop off", in which case user_visible_resume_ptid could
2296 return a wildcard ptid. */
2299 else
2301 }
2303 /* Wrapper for target_resume, that handles infrun-specific
2304 bookkeeping. */
2306 static void
2308 {
2313 /* Install inferior's terminal modes. */
2316 /* Avoid confusing the next resume, if the next stop/resume
2317 happens to apply to another thread. */
2320 /* Advise target which signals may be handled silently.
2322 If we have removed breakpoints because we are stepping over one
2323 in-line (in any thread), we need to receive all signals to avoid
2324 accidentally skipping a breakpoint during execution of a signal
2325 handler.
2327 Likewise if we're displaced stepping, otherwise a trap for a
2328 breakpoint in a signal handler might be confused with the
2329 displaced step finishing. We don't make the displaced_step_fixup
2330 step distinguish the cases instead, because:
2332 - a backtrace while stopped in the signal handler would show the
2333 scratch pad as frame older than the signal handler, instead of
2334 the real mainline code.
2336 - when the thread is later resumed, the signal handler would
2337 return to the scratch pad area, which would no longer be
2338 valid. */
2342 else
2348 }
2350 /* Resume the inferior. SIG is the signal to give the inferior
2351 (GDB_SIGNAL_0 for none). Note: don't call this directly; instead
2352 call 'resume', which handles exceptions. */
2354 static void
2356 {
2362 ptid_t resume_ptid;
2363 /* This represents the user's step vs continue request. When
2364 deciding whether "set scheduler-locking step" applies, it's the
2365 user's intention that counts. */
2367 /* This represents what we'll actually request the target to do.
2368 This can decay from a step to a continue, if e.g., we need to
2369 implement single-stepping with breakpoints (software
2370 single-step). */
2377 {
2379 {
2384 "infrun: resume: thread %s has pending wait "
2388 }
2392 /* FIXME: What should we do if we are supposed to resume this
2393 thread with a signal? Maybe we should maintain a queue of
2394 pending signals to deliver. */
2396 {
2399 }
2404 {
2406 /* Tell the event loop we have an event to process. */
2408 }
2410 }
2414 /* Depends on stepped_breakpoint. */
2418 {
2419 /* Don't try to single-step a vfork parent that is waiting for
2420 the child to get out of the shared memory region (by exec'ing
2421 or exiting). This is particularly important on software
2422 single-step archs, as the child process would trip on the
2423 software single step breakpoint inserted for the parent
2424 process. Since the parent will not actually execute any
2425 instruction until the child is out of the shared region (such
2426 are vfork's semantics), it is safe to simply continue it.
2427 Eventually, we'll see a TARGET_WAITKIND_VFORK_DONE event for
2428 the parent, and tell it to `keep_going', which automatically
2429 re-sets it stepping. */
2434 }
2438 "infrun: resume (step=%d, signal=%s), "
2445 /* Normally, by the time we reach `resume', the breakpoints are either
2446 removed or inserted, as appropriate. The exception is if we're sitting
2447 at a permanent breakpoint; we need to step over it, but permanent
2448 breakpoints can't be removed. So we have to test for it here. */
2450 {
2452 {
2453 /* We have a signal to pass to the inferior. The resume
2454 may, or may not take us to the signal handler. If this
2455 is a step, we'll need to stop in the signal handler, if
2456 there's one, (if the target supports stepping into
2457 handlers), or in the next mainline instruction, if
2458 there's no handler. If this is a continue, we need to be
2459 sure to run the handler with all breakpoints inserted.
2460 In all cases, set a breakpoint at the current address
2461 (where the handler returns to), and once that breakpoint
2462 is hit, resume skipping the permanent breakpoint. If
2463 that breakpoint isn't hit, then we've stepped into the
2464 signal handler (or hit some other event). We'll delete
2465 the step-resume breakpoint then. */
2469 "infrun: resume: skipping permanent breakpoint, "
2476 {
2477 /* Set a "high-priority" step-resume, as we don't want
2478 user breakpoints at PC to trigger (again) when this
2479 hits. */
2484 }
2487 }
2488 else
2489 {
2490 /* There's no signal to pass, we can go ahead and skip the
2491 permanent breakpoint manually. */
2496 /* Update pc to reflect the new address from which we will
2497 execute instructions. */
2501 {
2502 /* We've already advanced the PC, so the stepping part
2503 is done. Now we need to arrange for a trap to be
2504 reported to handle_inferior_event. Set a breakpoint
2505 at the current PC, and run to it. Don't update
2506 prev_pc, because if we end in
2507 switch_back_to_stepped_thread, we want the "expected
2508 thread advanced also" branch to be taken. IOW, we
2509 don't want this thread to step further from PC
2510 (overstep). */
2519 }
2520 }
2521 }
2523 /* If we have a breakpoint to step over, make sure to do a single
2524 step only. Same if we have software watchpoints. */
2528 /* If enabled, step over breakpoints by executing a copy of the
2529 instruction at a different address.
2531 We can't use displaced stepping when we have a signal to deliver;
2532 the comments for displaced_step_prepare explain why. The
2533 comments in the handle_inferior event for dealing with 'random
2534 signals' explain what we do instead.
2536 We can't use displaced stepping when we are waiting for vfork_done
2537 event, displaced stepping breaks the vfork child similarly as single
2538 step software breakpoint. */
2544 {
2548 {
2555 }
2557 {
2558 /* Fallback to stepping over the breakpoint in-line. */
2569 }
2571 {
2574 /* Update pc to reflect the new address from which we will
2575 execute instructions due to displaced stepping. */
2581 }
2582 }
2584 /* Do we need to do it the hard way, w/temp breakpoints? */
2588 /* Currently, our software single-step implementation leads to different
2589 results than hardware single-stepping in one situation: when stepping
2590 into delivering a signal which has an associated signal handler,
2591 hardware single-step will stop at the first instruction of the handler,
2592 while software single-step will simply skip execution of the handler.
2594 For now, this difference in behavior is accepted since there is no
2595 easy way to actually implement single-stepping into a signal handler
2596 without kernel support.
2598 However, there is one scenario where this difference leads to follow-on
2599 problems: if we're stepping off a breakpoint by removing all breakpoints
2600 and then single-stepping. In this case, the software single-step
2601 behavior means that even if there is a *breakpoint* in the signal
2602 handler, GDB still would not stop.
2604 Fortunately, we can at least fix this particular issue. We detect
2605 here the case where we are about to deliver a signal while software
2606 single-stepping with breakpoints removed. In this situation, we
2607 revert the decisions to remove all breakpoints and insert single-
2608 step breakpoints, and instead we install a step-resume breakpoint
2609 at the current address, deliver the signal without stepping, and
2610 once we arrive back at the step-resume breakpoint, actually step
2611 over the breakpoint we originally wanted to step over. */
2615 {
2616 /* If we have nested signals or a pending signal is delivered
2617 immediately after a handler returns, might might already have
2618 a step-resume breakpoint set on the earlier handler. We cannot
2619 set another step-resume breakpoint; just continue on until the
2620 original breakpoint is hit. */
2622 {
2625 }
2633 }
2635 /* If STEP is set, it's a request to use hardware stepping
2636 facilities. But in that case, we should never
2637 use singlestep breakpoint. */
2640 /* Decide the set of threads to ask the target to resume. */
2642 {
2643 /* We're allowing a thread to run past a breakpoint it has
2644 hit, either by single-stepping the thread with the breakpoint
2645 removed, or by displaced stepping, with the breakpoint inserted.
2646 In the former case, we need to single-step only this thread,
2647 and keep others stopped, as they can miss this breakpoint if
2648 allowed to run. That's not really a problem for displaced
2649 stepping, but, we still keep other threads stopped, in case
2650 another thread is also stopped for a breakpoint waiting for
2651 its turn in the displaced stepping queue. */
2653 }
2654 else
2659 {
2660 /* There are two cases where we currently need to step a
2661 breakpoint instruction when we have a signal to deliver:
2663 - See handle_signal_stop where we handle random signals that
2664 could take out us out of the stepping range. Normally, in
2665 that case we end up continuing (instead of stepping) over the
2666 signal handler with a breakpoint at PC, but there are cases
2667 where we should _always_ single-step, even if we have a
2668 step-resume breakpoint, like when a software watchpoint is
2669 set. Assuming single-stepping and delivering a signal at the
2670 same time would takes us to the signal handler, then we could
2671 have removed the breakpoint at PC to step over it. However,
2672 some hardware step targets (like e.g., Mac OS) can't step
2673 into signal handlers, and for those, we need to leave the
2674 breakpoint at PC inserted, as otherwise if the handler
2675 recurses and executes PC again, it'll miss the breakpoint.
2676 So we leave the breakpoint inserted anyway, but we need to
2677 record that we tried to step a breakpoint instruction, so
2678 that adjust_pc_after_break doesn't end up confused.
2680 - In non-stop if we insert a breakpoint (e.g., a step-resume)
2681 in one thread after another thread that was stepping had been
2682 momentarily paused for a step-over. When we re-resume the
2683 stepping thread, it may be resumed from that address with a
2684 breakpoint that hasn't trapped yet. Seen with
2685 gdb.threads/non-stop-fair-events.exp, on targets that don't
2686 do displaced stepping. */
2695 /* Most targets can step a breakpoint instruction, thus
2696 executing it normally. But if this one cannot, just
2697 continue and we will hit it anyway. */
2700 }
2706 {
2716 }
2719 {
2720 /* If we're resuming a thread with the PC out of the step
2721 range, then we're doing some nested/finer run control
2722 operation, like stepping the thread out of the dynamic
2723 linker or the displaced stepping scratch pad. We
2724 shouldn't have allowed a range step then. */
2726 }
2730 }
2732 /* Resume the inferior. SIG is the signal to give the inferior
2733 (GDB_SIGNAL_0 for none). This is a wrapper around 'resume_1' that
2734 rolls back state on error. */
2736 static void
2738 {
2739 TRY
2740 {
2742 }
2744 {
2745 /* If resuming is being aborted for any reason, delete any
2746 single-step breakpoint resume_1 may have created, to avoid
2747 confusing the following resumption, and to avoid leaving
2748 single-step breakpoints perturbing other threads, in case
2749 we're running in non-stop mode. */
2753 }
2754 END_CATCH
2755 }
2757 \f
2758 /* Proceeding. */
2760 /* See infrun.h. */
2762 /* Counter that tracks number of user visible stops. This can be used
2763 to tell whether a command has proceeded the inferior past the
2764 current location. This allows e.g., inferior function calls in
2765 breakpoint commands to not interrupt the command list. When the
2766 call finishes successfully, the inferior is standing at the same
2767 breakpoint as if nothing happened (and so we don't call
2768 normal_stop). */
2771 /* See infrun.h. */
2773 ULONGEST
2775 {
2777 }
2779 /* Called when we report a user visible stop. */
2781 static void
2783 {
2784 current_stop_id++;
2785 }
2787 /* Clear out all variables saying what to do when inferior is continued.
2788 First do this, then set the ones you want, then call `proceed'. */
2790 static void
2792 {
2798 /* If we're starting a new sequence, then the previous finished
2799 single-step is no longer relevant. */
2801 {
2803 {
2806 "infrun: clear_proceed_status: pending "
2807 "event of %s was a finished step. "
2813 }
2815 {
2820 "infrun: clear_proceed_status_thread: thread %s "
2821 "has pending wait status %s "
2825 }
2826 }
2828 /* If this signal should not be seen by program, give it zero.
2829 Used for debugging signals. */
2852 /* Discard any remaining commands or status from previous stop. */
2854 }
2856 void
2858 {
2859 /* With scheduler-locking replay, stop replaying other threads if we're
2860 not replaying the user-visible resume ptid.
2862 This is a convenience feature to not require the user to explicitly
2863 stop replaying the other threads. We're assuming that the user's
2864 intent is to resume tracing the recorded process. */
2868 execution_direction))
2872 {
2874 ptid_t resume_ptid;
2878 /* In all-stop mode, delete the per-thread status of all threads
2879 we're about to resume, implicitly and explicitly. */
2881 {
2885 }
2886 }
2889 {
2893 {
2894 /* If in non-stop mode, only delete the per-thread status of
2895 the current thread. */
2897 }
2901 }
2904 }
2906 /* Returns true if TP is still stopped at a breakpoint that needs
2907 stepping-over in order to make progress. If the breakpoint is gone
2908 meanwhile, we can skip the whole step-over dance. */
2910 static int
2912 {
2914 {
2923 }
2926 }
2928 /* Check whether thread TP still needs to start a step-over in order
2929 to make progress when resumed. Returns an bitwise or of enum
2930 step_over_what bits, indicating what needs to be stepped over. */
2932 static step_over_what
2934 {
2945 }
2947 /* Returns true if scheduler locking applies. STEP indicates whether
2948 we're about to do a step/next-like command to a thread. */
2950 static int
2952 {
2958 execution_direction)));
2959 }
2961 /* Basic routine for continuing the program in various fashions.
2963 ADDR is the address to resume at, or -1 for resume where stopped.
2964 SIGGNAL is the signal to give it, or GDB_SIGNAL_0 for none,
2965 or GDB_SIGNAL_DEFAULT for act according to how it stopped.
2967 You should call clear_proceed_status before calling proceed. */
2969 void
2971 {
2975 CORE_ADDR pc;
2976 ptid_t resume_ptid;
2981 /* If we're stopped at a fork/vfork, follow the branch set by the
2982 "set follow-fork-mode" command; otherwise, we'll just proceed
2983 resuming the current thread. */
2985 {
2986 /* The target for some reason decided not to resume. */
2991 }
2993 /* We'll update this if & when we switch to a new thread. */
3003 /* Fill in with reasonable starting values. */
3009 {
3013 /* There is a breakpoint at the address we will resume at,
3014 step one instruction before inserting breakpoints so that
3015 we do not stop right away (and report a second hit at this
3016 breakpoint).
3018 Note, we don't do this in reverse, because we won't
3019 actually be executing the breakpoint insn anyway.
3020 We'll be (un-)executing the previous instruction. */
3025 /* We stepped onto an instruction that needs to be stepped
3026 again before re-inserting the breakpoint, do so. */
3028 }
3029 else
3030 {
3032 }
3039 /* If an exception is thrown from this point on, make sure to
3040 propagate GDB's knowledge of the executing state to the
3041 frontend/user running state. */
3044 /* Even if RESUME_PTID is a wildcard, and we end up resuming fewer
3045 threads (e.g., we might need to set threads stepping over
3046 breakpoints first), from the user/frontend's point of view, all
3047 threads in RESUME_PTID are now running. Unless we're calling an
3048 inferior function, as in that case we pretend the inferior
3049 doesn't run at all. */
3061 /* Make sure that output from GDB appears before output from the
3062 inferior. */
3065 /* Since we've marked the inferior running, give it the terminal. A
3066 QUIT/Ctrl-C from here on is forwarded to the target (which can
3067 still detect attempts to unblock a stuck connection with repeated
3068 Ctrl-C from within target_pass_ctrlc). */
3071 /* In a multi-threaded task we may select another thread and
3072 then continue or step.
3074 But if a thread that we're resuming had stopped at a breakpoint,
3075 it will immediately cause another breakpoint stop without any
3076 execution (i.e. it will report a breakpoint hit incorrectly). So
3077 we must step over it first.
3079 Look for threads other than the current (TP) that reported a
3080 breakpoint hit and haven't been resumed yet since. */
3082 /* If scheduler locking applies, we can avoid iterating over all
3083 threads. */
3085 {
3089 {
3090 /* Ignore the current thread here. It's handled
3091 afterwards. */
3095 /* Ignore threads of processes we're not resuming. */
3110 }
3113 }
3115 /* Enqueue the current thread last, so that we move all other
3116 threads over their breakpoints first. */
3120 /* If the thread isn't started, we'll still need to set its prev_pc,
3121 so that switch_back_to_stepped_thread knows the thread hasn't
3122 advanced. Must do this before resuming any thread, as in
3123 all-stop/remote, once we resume we can't send any other packet
3124 until the target stops again. */
3127 {
3133 {
3134 /* Either this thread started a new in-line step over, or some
3135 other thread was already doing one. In either case, don't
3136 resume anything else until the step-over is finished. */
3137 }
3139 {
3140 /* A new displaced stepping sequence was started. In all-stop,
3141 we can't talk to the target anymore until it next stops. */
3142 }
3144 {
3145 /* In all-stop, but the target is always in non-stop mode.
3146 Start all other threads that are implicitly resumed too. */
3148 {
3149 /* Ignore threads of processes we're not resuming. */
3154 {
3161 }
3164 {
3170 }
3182 }
3183 }
3185 {
3186 /* The thread wasn't started, and isn't queued, run it now. */
3192 }
3193 }
3199 /* Tell the event loop to wait for it to stop. If the target
3200 supports asynchronous execution, it'll do this from within
3201 target_resume. */
3204 }
3205 \f
3207 /* Start remote-debugging of a machine over a serial link. */
3209 void
3211 {
3217 /* Always go on waiting for the target, regardless of the mode. */
3218 /* FIXME: cagney/1999-09-23: At present it isn't possible to
3219 indicate to wait_for_inferior that a target should timeout if
3220 nothing is returned (instead of just blocking). Because of this,
3221 targets expecting an immediate response need to, internally, set
3222 things up so that the target_wait() is forced to eventually
3223 timeout. */
3224 /* FIXME: cagney/1999-09-24: It isn't possible for target_open() to
3225 differentiate to its caller what the state of the target is after
3226 the initial open has been performed. Here we're assuming that
3227 the target has stopped. It should be possible to eventually have
3228 target_open() return to the caller an indication that the target
3229 is currently running and GDB state should be set to the same as
3230 for an async run. */
3233 /* Now that the inferior has stopped, do any bookkeeping like
3234 loading shared libraries. We want to do this before normal_stop,
3235 so that the displayed frame is up to date. */
3239 }
3241 /* Initialize static vars when a new inferior begins. */
3243 void
3245 {
3246 /* These are meaningless until the first time through wait_for_inferior. */
3256 /* Discard any skipped inlined frames. */
3258 }
3260 \f
3278 /* This function is attached as a "thread_stop_requested" observer.
3279 Cleanup local state that assumed the PTID was to be resumed, and
3280 report the stop to the frontend. */
3282 static void
3284 {
3287 /* PTID was requested to stop. If the thread was already stopped,
3288 but the user/frontend doesn't know about that yet (e.g., the
3289 thread had been temporarily paused for some step-over), set up
3290 for reporting the stop now. */
3293 {
3299 /* Remove matching threads from the step-over queue, so
3300 start_step_over doesn't try to resume them
3301 automatically. */
3305 /* If the thread is stopped, but the user/frontend doesn't
3306 know about that yet, queue a pending event, as if the
3307 thread had just stopped now. Unless the thread already had
3308 a pending event. */
3310 {
3314 }
3316 /* Clear the inline-frame state, since we're re-processing the
3317 stop. */
3320 /* If this thread was paused because some other thread was
3321 doing an inline-step over, let that finish first. Once
3322 that happens, we'll restart all threads and consume pending
3323 stop events then. */
3327 /* Otherwise we can process the (new) pending event now. Set
3328 it so this pending event is considered by
3329 do_target_wait. */
3331 }
3332 }
3334 static void
3336 {
3339 }
3341 /* Delete the step resume, single-step and longjmp/exception resume
3342 breakpoints of TP. */
3344 static void
3346 {
3350 }
3352 /* If the target still has execution, call FUNC for each thread that
3353 just stopped. In all-stop, that's all the non-exited threads; in
3354 non-stop, that's the current thread, only. */
3359 static void
3361 {
3366 {
3367 /* If in non-stop mode, only the current thread stopped. */
3369 }
3370 else
3371 {
3374 /* In all-stop mode, all threads have stopped. */
3376 {
3378 }
3379 }
3380 }
3382 /* Delete the step resume and longjmp/exception resume breakpoints of
3383 the threads that just stopped. */
3385 static void
3387 {
3389 }
3391 /* Delete the single-step breakpoints of the threads that just
3392 stopped. */
3394 static void
3396 {
3398 }
3400 /* A cleanup wrapper. */
3402 static void
3404 {
3406 }
3408 /* See infrun.h. */
3410 void
3413 {
3415 string_file stb;
3417 /* The text is split over several lines because it was getting too long.
3418 Call fprintf_unfiltered (gdb_stdlog) once so that the text is still
3419 output as a unit; we want only one timestamp printed if debug_timestamp
3420 is set. */
3436 /* This uses %s in part to handle %'s in the text, but also to avoid
3437 a gcc error: the format attribute requires a string literal. */
3439 }
3441 /* Select a thread at random, out of those which are resumed and have
3442 had events. */
3446 {
3451 /* First see how many events we have. Count only resumed threads
3452 that have an event pending. */
3457 num_events++;
3462 /* Now randomly pick a thread out of those that have had events. */
3471 /* Select the Nth thread that has had an event. */
3480 }
3482 /* Wrapper for target_wait that first checks whether threads have
3483 pending statuses to report before actually asking the target for
3484 more events. */
3486 static ptid_t
3488 {
3489 ptid_t event_ptid;
3492 /* First check if there is a resumed thread with a wait status
3493 pending. */
3495 {
3497 }
3498 else
3499 {
3505 /* We have a specific thread to check. */
3510 }
3515 {
3518 CORE_ADDR pc;
3524 {
3532 }
3534 {
3542 }
3545 {
3553 }
3554 }
3557 {
3559 {
3567 }
3569 /* Now that we've selected our final event LWP, un-adjust its PC
3570 if it was a software breakpoint (and the target doesn't
3571 always adjust the PC itself). */
3574 {
3584 {
3585 CORE_ADDR pc;
3589 }
3590 }
3596 /* Wake up the event loop again, until all pending events are
3597 processed. */
3601 }
3603 /* But if we don't find one, we'll have to wait. */
3607 else
3611 }
3613 /* Prepare and stabilize the inferior for detaching it. E.g.,
3614 detaching while a thread is displaced stepping is a recipe for
3615 crashing it, as nothing would readjust the PC out of the scratch
3616 pad. */
3618 void
3620 {
3626 /* Is any thread of this process displaced stepping? If not,
3627 there's nothing else to do. */
3638 {
3646 /* Flush target cache before starting to handle each event.
3647 Target was running and cache could be stale. This is just a
3648 heuristic. Running threads may modify target memory, but we
3649 don't get any event. */
3657 /* If an error happens while handling the event, propagate GDB's
3658 knowledge of the executing state to the frontend/user running
3659 state. */
3662 /* Now figure out what to do with the result of the result. */
3665 /* No error, don't finish the state yet. */
3668 /* Breakpoints and watchpoints are not installed on the target
3669 at this point, and signals are passed directly to the
3670 inferior, so this must mean the process is gone. */
3672 {
3675 }
3676 }
3679 }
3681 /* Wait for control to return from inferior to debugger.
3683 If inferior gets a signal, we may decide to start it up again
3684 instead of returning. That is why there is a loop in this function.
3685 When this function actually returns it means the inferior
3686 should be left stopped and GDB should read more commands. */
3688 void
3690 {
3694 fprintf_unfiltered
3697 old_cleanups
3699 NULL);
3701 /* If an error happens while handling the event, propagate GDB's
3702 knowledge of the executing state to the frontend/user running
3703 state. */
3707 {
3716 /* Flush target cache before starting to handle each event.
3717 Target was running and cache could be stale. This is just a
3718 heuristic. Running threads may modify target memory, but we
3719 don't get any event. */
3727 /* Now figure out what to do with the result of the result. */
3732 }
3734 /* No error, don't finish the state yet. */
3738 }
3740 /* Cleanup that reinstalls the readline callback handler, if the
3741 target is running in the background. If while handling the target
3742 event something triggered a secondary prompt, like e.g., a
3743 pagination prompt, we'll have removed the callback handler (see
3744 gdb_readline_wrapper_line). Need to do this as we go back to the
3745 event loop, ready to process further input. Note this has no
3746 effect if the handler hasn't actually been removed, because calling
3747 rl_callback_handler_install resets the line buffer, thus losing
3748 input. */
3750 static void
3752 {
3756 {
3757 /* We're not going back to the top level event loop yet. Don't
3758 install the readline callback, as it'd prep the terminal,
3759 readline-style (raw, noecho) (e.g., --batch). We'll install
3760 it the next time the prompt is displayed, when we're ready
3761 for input. */
3763 }
3767 }
3769 /* Clean up the FSMs of threads that are now stopped. In non-stop,
3770 that's just the event thread. In all-stop, that's all threads. */
3772 static void
3774 {
3781 {
3783 {
3791 }
3795 }
3796 }
3798 /* Helper for all_uis_check_sync_execution_done that works on the
3799 current UI. */
3801 static void
3803 {
3809 {
3813 }
3814 }
3816 /* See infrun.h. */
3818 void
3820 {
3822 {
3824 }
3825 }
3827 /* See infrun.h. */
3829 void
3831 {
3833 {
3836 }
3837 }
3839 /* Asynchronous version of wait_for_inferior. It is called by the
3840 event loop whenever a change of state is detected on the file
3841 descriptor corresponding to the target. It can be called more than
3842 once to complete a single execution command. In such cases we need
3843 to keep the state in a global variable ECSS. If it is the last time
3844 that this function is called for a single execution command, then
3845 report to the user that the inferior has stopped, and do the
3846 necessary cleanups. */
3848 void
3850 {
3859 /* Events are always processed with the main UI as current UI. This
3860 way, warnings, debug output, etc. are always consistently sent to
3861 the main console. */
3864 /* End up with readline processing input, if necessary. */
3867 /* We're handling a live event, so make sure we're doing live
3868 debugging. If we're looking at traceframes while the target is
3869 running, we're going to need to get back to that mode after
3870 handling the event. */
3873 {
3876 }
3881 /* In non-stop mode, the user/frontend should not notice a thread
3882 switch due to internal events. Make sure we reverse to the
3883 user selected thread and frame after handling the event and
3884 running any breakpoint commands. */
3888 /* Flush target cache before starting to handle each event. Target
3889 was running and cache could be stale. This is just a heuristic.
3890 Running threads may modify target memory, but we don't get any
3891 event. */
3894 scoped_restore save_exec_dir
3903 /* If an error happens while handling the event, propagate GDB's
3904 knowledge of the executing state to the frontend/user running
3905 state. */
3909 /* Get executed before make_cleanup_restore_current_thread above to apply
3910 still for the thread which has thrown the exception. */
3915 /* Now figure out what to do with the result of the result. */
3919 {
3927 {
3932 }
3935 {
3937 }
3938 else
3939 {
3946 {
3947 should_notify_stop
3949 }
3952 {
3953 /* We may not find an inferior if this was a process exit. */
3956 }
3959 {
3962 }
3963 }
3964 }
3968 /* No error, don't finish the thread states yet. */
3971 /* Revert thread and frame. */
3974 /* If a UI was in sync execution mode, and now isn't, restore its
3975 prompt (a synchronous execution command has finished, and we're
3976 ready for input). */
3980 && exec_done_display_p
3984 }
3986 /* Record the frame and location we're currently stepping through. */
3987 void
3989 {
3997 }
3999 /* Clear context switchable stepping state. */
4001 void
4003 {
4008 }
4010 /* Set the cached copy of the last ptid/waitstatus. */
4012 void
4014 {
4017 }
4019 /* Return the cached copy of the last pid/waitstatus returned by
4020 target_wait()/deprecated_target_wait_hook(). The data is actually
4021 cached by handle_inferior_event(), which gets called immediately
4022 after target_wait()/deprecated_target_wait_hook(). */
4024 void
4026 {
4029 }
4031 void
4033 {
4035 }
4037 /* Switch thread contexts. */
4039 static void
4041 {
4045 {
4050 }
4053 }
4055 /* If the target can't tell whether we've hit breakpoints
4056 (target_supports_stopped_by_sw_breakpoint), and we got a SIGTRAP,
4057 check whether that could have been caused by a breakpoint. If so,
4058 adjust the PC, per gdbarch_decr_pc_after_break. */
4060 static void
4063 {
4068 /* If we've hit a breakpoint, we'll normally be stopped with SIGTRAP. If
4069 we aren't, just return.
4071 We assume that waitkinds other than TARGET_WAITKIND_STOPPED are not
4072 affected by gdbarch_decr_pc_after_break. Other waitkinds which are
4073 implemented by software breakpoints should be handled through the normal
4074 breakpoint layer.
4076 NOTE drow/2004-01-31: On some targets, breakpoints may generate
4077 different signals (SIGILL or SIGEMT for instance), but it is less
4078 clear where the PC is pointing afterwards. It may not match
4079 gdbarch_decr_pc_after_break. I don't know any specific target that
4080 generates these signals at breakpoints (the code has been in GDB since at
4081 least 1992) so I can not guess how to handle them here.
4083 In earlier versions of GDB, a target with
4084 gdbarch_have_nonsteppable_watchpoint would have the PC after hitting a
4085 watchpoint affected by gdbarch_decr_pc_after_break. I haven't found any
4086 target with both of these set in GDB history, and it seems unlikely to be
4087 correct, so gdbarch_have_nonsteppable_watchpoint is not checked here. */
4095 /* In reverse execution, when a breakpoint is hit, the instruction
4096 under it has already been de-executed. The reported PC always
4097 points at the breakpoint address, so adjusting it further would
4098 be wrong. E.g., consider this case on a decr_pc_after_break == 1
4099 architecture:
4101 B1 0x08000000 : INSN1
4102 B2 0x08000001 : INSN2
4103 0x08000002 : INSN3
4104 PC -> 0x08000003 : INSN4
4106 Say you're stopped at 0x08000003 as above. Reverse continuing
4107 from that point should hit B2 as below. Reading the PC when the
4108 SIGTRAP is reported should read 0x08000001 and INSN2 should have
4109 been de-executed already.
4111 B1 0x08000000 : INSN1
4112 B2 PC -> 0x08000001 : INSN2
4113 0x08000002 : INSN3
4114 0x08000003 : INSN4
4116 We can't apply the same logic as for forward execution, because
4117 we would wrongly adjust the PC to 0x08000000, since there's a
4118 breakpoint at PC - 1. We'd then report a hit on B1, although
4119 INSN1 hadn't been de-executed yet. Doing nothing is the correct
4120 behaviour. */
4124 /* If the target can tell whether the thread hit a SW breakpoint,
4125 trust it. Targets that can tell also adjust the PC
4126 themselves. */
4130 /* Note that relying on whether a breakpoint is planted in memory to
4131 determine this can fail. E.g,. the breakpoint could have been
4132 removed since. Or the thread could have been told to step an
4133 instruction the size of a breakpoint instruction, and only
4134 _after_ was a breakpoint inserted at its address. */
4136 /* If this target does not decrement the PC after breakpoints, then
4137 we have nothing to do. */
4147 /* Find the location where (if we've hit a breakpoint) the
4148 breakpoint would be. */
4151 /* If the target can't tell whether a software breakpoint triggered,
4152 fallback to figuring it out based on breakpoints we think were
4153 inserted in the target, and on whether the thread was stepped or
4154 continued. */
4156 /* Check whether there actually is a software breakpoint inserted at
4157 that location.
4159 If in non-stop mode, a race condition is possible where we've
4160 removed a breakpoint, but stop events for that breakpoint were
4161 already queued and arrive later. To suppress those spurious
4162 SIGTRAPs, we keep a list of such breakpoint locations for a bit,
4163 and retire them after a number of stop events are reported. Note
4164 this is an heuristic and can thus get confused. The real fix is
4165 to get the "stopped by SW BP and needs adjustment" info out of
4166 the target/kernel (and thus never reach here; see above). */
4170 {
4174 restore_operation_disable.emplace
4177 /* When using hardware single-step, a SIGTRAP is reported for both
4178 a completed single-step and a software breakpoint. Need to
4179 differentiate between the two, as the latter needs adjusting
4180 but the former does not.
4182 The SIGTRAP can be due to a completed hardware single-step only if
4183 - we didn't insert software single-step breakpoints
4184 - this thread is currently being stepped
4186 If any of these events did not occur, we must have stopped due
4187 to hitting a software breakpoint, and have to back up to the
4188 breakpoint address.
4190 As a special case, we could have hardware single-stepped a
4191 software breakpoint. In this case (prev_pc == breakpoint_pc),
4192 we also need to back up to the breakpoint address. */
4199 }
4200 }
4202 static int
4204 {
4208 {
4213 }
4216 }
4218 /* If the event thread has the stop requested flag set, pretend it
4219 stopped for a GDB_SIGNAL_0 (i.e., as if it stopped due to
4220 target_stop). */
4222 static bool
4224 {
4226 {
4231 }
4233 }
4235 /* Auxiliary function that handles syscall entry/return events.
4236 It returns 1 if the inferior should keep going (and GDB
4237 should ignore the event), or 0 if the event deserves to be
4238 processed. */
4240 static int
4242 {
4254 {
4257 syscall_number);
4268 {
4269 /* Catchpoint hit. */
4271 }
4272 }
4277 /* If no catchpoint triggered for this, then keep going. */
4280 }
4282 /* Lazily fill in the execution_control_state's stop_func_* fields. */
4284 static void
4287 {
4289 {
4290 /* Don't care about return value; stop_func_start and stop_func_name
4291 will both be 0 if it doesn't work. */
4296 ecs->stop_func_start
4304 }
4305 }
4308 /* Return the STOP_SOON field of the inferior pointed at by ECS. */
4310 static enum stop_kind
4312 {
4317 }
4319 /* Wait for one event. Store the resulting waitstatus in WS, and
4320 return the event ptid. */
4322 static ptid_t
4324 {
4325 ptid_t event_ptid;
4330 /* Flush target cache before starting to handle each event.
4331 Target was running and cache could be stale. This is just a
4332 heuristic. Running threads may modify target memory, but we
4333 don't get any event. */
4338 else
4345 }
4347 /* Generate a wrapper for target_stopped_by_REASON that works on PTID
4348 instead of the current thread. */
4349 #define THREAD_STOPPED_BY(REASON) \
4350 static int \
4351 thread_stopped_by_ ## REASON (ptid_t ptid) \
4352 { \
4353 scoped_restore save_inferior_ptid = make_scoped_restore (&inferior_ptid); \
4354 inferior_ptid = ptid; \
4355 \
4356 return target_stopped_by_ ## REASON (); \
4357 }
4359 /* Generate thread_stopped_by_watchpoint. */
4361 /* Generate thread_stopped_by_sw_breakpoint. */
4363 /* Generate thread_stopped_by_hw_breakpoint. */
4366 /* Save the thread's event and stop reason to process it later. */
4368 static void
4370 {
4372 {
4381 }
4383 /* Record for later. */
4392 {
4398 {
4401 }
4404 {
4407 }
4410 {
4413 }
4416 pc))
4417 {
4420 }
4423 pc))
4424 {
4427 }
4430 {
4433 }
4434 }
4435 }
4437 /* A cleanup that disables thread create/exit events. */
4439 static void
4441 {
4443 }
4445 /* See infrun.h. */
4447 void
4449 {
4450 /* We may need multiple passes to discover all threads. */
4460 scoped_restore_current_thread restore_thread;
4465 /* Request threads to stop, and then wait for the stops. Because
4466 threads we already know about can spawn more threads while we're
4467 trying to stop them, and we only learn about new threads when we
4468 update the thread list, do this in a loop, and keep iterating
4469 until two passes find no threads that need to be stopped. */
4471 {
4474 "infrun: stop_all_threads, pass=%d, "
4477 {
4478 ptid_t event_ptid;
4485 /* Go through all threads looking for threads that we need
4486 to tell the target to stop. */
4488 {
4490 {
4491 /* If already stopping, don't request a stop again.
4492 We just haven't seen the notification yet. */
4494 {
4497 "infrun: %s executing, "
4502 }
4503 else
4504 {
4507 "infrun: %s executing, "
4510 }
4514 }
4515 else
4516 {
4522 /* The thread may be not executing, but still be
4523 resumed with a pending status to process. */
4525 }
4526 }
4531 /* If we find new threads on the second iteration, restart
4532 over. We want to see two iterations in a row with all
4533 threads stopped. */
4540 {
4541 /* All resumed threads exited. */
4542 }
4546 {
4548 {
4552 "infrun: %s exited while "
4555 }
4556 }
4557 else
4558 {
4570 /* This may be the first time we see the inferior report
4571 a stop. */
4574 {
4577 }
4581 {
4582 /* We caught the event that we intended to catch, so
4583 there's no event pending. */
4588 {
4589 /* Add it back to the step-over queue. */
4591 {
4593 "infrun: displaced-step of %s "
4594 "canceled: adding back to the "
4597 }
4600 }
4601 }
4602 else
4603 {
4608 {
4612 "infrun: target_wait %s, saving "
4618 }
4620 /* Record for later. */
4627 {
4628 /* Add it back to the step-over queue. */
4631 }
4637 {
4639 "infrun: saved stop_pc=%s for %s "
4645 }
4646 }
4647 }
4648 }
4649 }
4655 }
4657 /* Handle a TARGET_WAITKIND_NO_RESUMED event. */
4659 static int
4661 {
4666 {
4671 {
4673 {
4676 }
4677 }
4679 {
4680 /* There were no unwaited-for children left in the target, but,
4681 we're not synchronously waiting for events either. Just
4682 ignore. */
4686 "infrun: TARGET_WAITKIND_NO_RESUMED "
4690 }
4691 }
4693 /* Otherwise, if we were running a synchronous execution command, we
4694 may need to cancel it and give the user back the terminal.
4696 In non-stop mode, the target can't tell whether we've already
4697 consumed previous stop events, so it can end up sending us a
4698 no-resumed event like so:
4700 #0 - thread 1 is left stopped
4702 #1 - thread 2 is resumed and hits breakpoint
4703 -> TARGET_WAITKIND_STOPPED
4705 #2 - thread 3 is resumed and exits
4706 this is the last resumed thread, so
4707 -> TARGET_WAITKIND_NO_RESUMED
4709 #3 - gdb processes stop for thread 2 and decides to re-resume
4710 it.
4712 #4 - gdb processes the TARGET_WAITKIND_NO_RESUMED event.
4713 thread 2 is now resumed, so the event should be ignored.
4715 IOW, if the stop for thread 2 doesn't end a foreground command,
4716 then we need to ignore the following TARGET_WAITKIND_NO_RESUMED
4717 event. But it could be that the event meant that thread 2 itself
4718 (or whatever other thread was the last resumed thread) exited.
4720 To address this we refresh the thread list and check whether we
4721 have resumed threads _now_. In the example above, this removes
4722 thread 3 from the thread list. If thread 2 was re-resumed, we
4723 ignore this event. If we find no thread resumed, then we cancel
4724 the synchronous command show "no unwaited-for " to the user. */
4728 {
4731 {
4732 /* There were no unwaited-for children left in the target at
4733 some point, but there are now. Just ignore. */
4736 "infrun: TARGET_WAITKIND_NO_RESUMED "
4740 }
4741 }
4743 /* Note however that we may find no resumed thread because the whole
4744 process exited meanwhile (thus updating the thread list results
4745 in an empty thread list). In this case we know we'll be getting
4746 a process exit event shortly. */
4748 {
4754 {
4757 "infrun: TARGET_WAITKIND_NO_RESUMED "
4761 }
4762 }
4764 /* Go ahead and report the event. */
4766 }
4768 /* Given an execution control state that has been freshly filled in by
4769 an event from the inferior, figure out what it means and take
4770 appropriate action.
4772 The alternatives are:
4774 1) stop_waiting and return; to really stop and return to the
4775 debugger.
4777 2) keep_going and return; to wait for the next event (set
4778 ecs->event_thread->stepping_over_breakpoint to 1 to single step
4779 once). */
4781 static void
4783 {
4787 {
4788 /* We had an event in the inferior, but we are not interested in
4789 handling it at this level. The lower layers have already
4790 done what needs to be done, if anything.
4792 One of the possible circumstances for this is when the
4793 inferior produces output for the console. The inferior has
4794 not stopped, and we are ignoring the event. Another possible
4795 circumstance is any event which the lower level knows will be
4796 reported multiple times without an intervening resume. */
4801 }
4804 {
4809 }
4815 /* Cache the last pid/waitstatus. */
4818 /* Always clear state belonging to the previous time we stopped. */
4822 {
4823 /* No unwaited-for children left. IOW, all resumed children
4824 have exited. */
4831 }
4835 {
4837 /* If it's a new thread, add it to the thread database. */
4841 /* Disable range stepping. If the next step request could use a
4842 range, this will be end up re-enabled then. */
4844 }
4846 /* Dependent on valid ECS->EVENT_THREAD. */
4849 /* Dependent on the current PC value modified by adjust_pc_after_break. */
4854 /* First, distinguish signals caused by the debugger from signals
4855 that have to do with the program's own actions. Note that
4856 breakpoint insns may cause SIGTRAP or SIGILL or SIGEMT, depending
4857 on the operating system version. Here we detect when a SIGILL or
4858 SIGEMT is really a breakpoint and change it to SIGTRAP. We do
4859 something similar for SIGSEGV, since a SIGSEGV will be generated
4860 when we're trying to execute a breakpoint instruction on a
4861 non-executable stack. This happens for call dummy breakpoints
4862 for architectures like SPARC that place call dummies on the
4863 stack. */
4868 {
4873 {
4878 }
4879 }
4881 /* Mark the non-executing threads accordingly. In all-stop, all
4882 threads of all processes are stopped when we get any event
4883 reported. In non-stop mode, only the event thread stops. */
4884 {
4885 ptid_t mark_ptid;
4891 {
4892 /* If we're handling a process exit in non-stop mode, even
4893 though threads haven't been deleted yet, one would think
4894 that there is nothing to do, as threads of the dead process
4895 will be soon deleted, and threads of any other process were
4896 left running. However, on some targets, threads survive a
4897 process exit event. E.g., for the "checkpoint" command,
4898 when the current checkpoint/fork exits, linux-fork.c
4899 automatically switches to another fork from within
4900 target_mourn_inferior, by associating the same
4901 inferior/thread to another fork. We haven't mourned yet at
4902 this point, but we must mark any threads left in the
4903 process as not-executing so that finish_thread_state marks
4904 them stopped (in the user's perspective) if/when we present
4905 the stop to the user. */
4907 }
4908 else
4913 /* Likewise the resumed flag. */
4915 }
4918 {
4923 /* Ignore gracefully during startup of the inferior, as it might
4924 be the shell which has just loaded some objects, otherwise
4925 add the symbols for the newly loaded objects. Also ignore at
4926 the beginning of an attach or remote session; we will query
4927 the full list of libraries once the connection is
4928 established. */
4932 {
4948 {
4949 /* A catchpoint triggered. */
4952 }
4954 /* If requested, stop when the dynamic linker notifies
4955 gdb of events. This allows the user to get control
4956 and place breakpoints in initializer routines for
4957 dynamically loaded objects (among other things). */
4960 {
4961 /* Make sure we print "Stopped due to solib-event" in
4962 normal_stop. */
4967 }
4968 }
4970 /* If we are skipping through a shell, or through shared library
4971 loading that we aren't interested in, resume the program. If
4972 we're running the program normally, also resume. */
4974 {
4975 /* Loading of shared libraries might have changed breakpoint
4976 addresses. Make sure new breakpoints are inserted. */
4982 }
4984 /* But stop if we're attaching or setting up a remote
4985 connection. */
4988 {
4993 }
5021 {
5025 else
5028 }
5036 /* Clearing any previous state of convenience variables. */
5040 {
5041 /* Record the exit code in the convenience variable $_exitcode, so
5042 that the user can inspect this again later. */
5046 /* Also record this in the inferior itself. */
5050 /* Support the --return-child-result option. */
5054 }
5055 else
5056 {
5060 {
5061 /* Set the value of the internal variable $_exitsignal,
5062 which holds the signal uncaught by the inferior. */
5066 }
5067 else
5068 {
5069 /* We don't have access to the target's method used for
5070 converting between signal numbers (GDB's internal
5071 representation <-> target's representation).
5072 Therefore, we cannot do a good job at displaying this
5073 information to the user. It's better to just warn
5074 her about it (if infrun debugging is enabled), and
5075 give up. */
5079 }
5082 }
5090 /* The following are the only cases in which we keep going;
5091 the above cases end in a continue or goto. */
5095 {
5098 else
5100 }
5102 /* Check whether the inferior is displaced stepping. */
5103 {
5107 /* If checking displaced stepping is supported, and thread
5108 ecs->ptid is displaced stepping. */
5110 {
5114 CORE_ADDR parent_pc;
5116 /* GDB has got TARGET_WAITKIND_FORKED or TARGET_WAITKIND_VFORKED,
5117 indicating that the displaced stepping of syscall instruction
5118 has been done. Perform cleanup for parent process here. Note
5119 that this operation also cleans up the child process for vfork,
5120 because their pages are shared. */
5122 /* Start a new step-over in another thread if there's one
5123 that needs it. */
5127 {
5131 /* Restore scratch pad for child process. */
5133 }
5135 /* Since the vfork/fork syscall instruction was executed in the scratchpad,
5136 the child's PC is also within the scratchpad. Set the child's PC
5137 to the parent's PC value, which has already been fixed up.
5138 FIXME: we use the parent's aspace here, although we're touching
5139 the child, because the child hasn't been added to the inferior
5140 list yet at this point. */
5142 child_regcache
5144 gdbarch,
5146 /* Read PC value of parent process. */
5157 }
5158 }
5162 /* Immediately detach breakpoints from the child before there's
5163 any chance of letting the user delete breakpoints from the
5164 breakpoint lists. If we don't do this early, it's easy to
5165 leave left over traps in the child, vis: "break foo; catch
5166 fork; c; <fork>; del; c; <child calls foo>". We only follow
5167 the fork on the last `continue', and by that time the
5168 breakpoint at "foo" is long gone from the breakpoint table.
5169 If we vforked, then we don't need to unpatch here, since both
5170 parent and child are sharing the same memory pages; we'll
5171 need to unpatch at follow/detach time instead to be certain
5172 that new breakpoints added between catchpoint hit time and
5173 vfork follow are detached. */
5175 {
5176 /* This won't actually modify the breakpoint list, but will
5177 physically remove the breakpoints from the child. */
5179 }
5183 /* In case the event is caught by a catchpoint, remember that
5184 the event is to be followed at the next resume of the thread,
5185 and not immediately. */
5199 /* If no catchpoint triggered for this, then keep going. Note
5200 that we're interested in knowing the bpstat actually causes a
5201 stop, not just if it may explain the signal. Software
5202 watchpoints, for example, always appear in the bpstat. */
5204 {
5206 int follow_child
5216 /* At this point, the parent is marked running, and the
5217 child is marked stopped. */
5219 /* If not resuming the parent, mark it stopped. */
5223 /* If resuming the child, mark it running. */
5227 /* In non-stop mode, also resume the other branch. */
5230 {
5233 else
5239 }
5243 else
5251 else
5254 }
5259 /* Done with the shared memory region. Re-insert breakpoints in
5260 the parent, and keep going. */
5274 /* This also takes care of reinserting breakpoints in the
5275 previously locked inferior. */
5283 /* Note we can't read registers yet (the stop_pc), because we
5284 don't yet know the inferior's post-exec architecture.
5285 'stop_pc' is explicitly read below instead. */
5288 /* Do whatever is necessary to the parent branch of the vfork. */
5291 /* This causes the eventpoints and symbol table to be reset.
5292 Must do this now, before trying to determine whether to
5293 stop. */
5296 /* In follow_exec we may have deleted the original thread and
5297 created a new one. Make sure that the event thread is the
5298 execd thread for that case (this is a nop otherwise). */
5309 /* Note that this may be referenced from inside
5310 bpstat_stop_status above, through inferior_has_execd. */
5317 /* If no catchpoint triggered for this, then keep going. */
5319 {
5323 }
5327 /* Be careful not to try to gather much state about a thread
5328 that's in a syscall. It's frequently a losing proposition. */
5333 /* Getting the current syscall number. */
5338 /* Before examining the threads further, step this thread to
5339 get it entirely out of the syscall. (We get notice of the
5340 event when the thread is just on the verge of exiting a
5341 syscall. Stepping one instruction seems to get it back
5342 into user code.) */
5360 /* Reverse execution: target ran out of history info. */
5362 /* Switch to the stopped thread. */
5377 }
5378 }
5380 /* A wrapper around handle_inferior_event_1, which also makes sure
5381 that all temporary struct value objects that were created during
5382 the handling of the event get deleted at the end. */
5384 static void
5386 {
5390 /* Purge all temporary values created during the event handling,
5391 as it could be a long time before we return to the command level
5392 where such values would otherwise be purged. */
5394 }
5396 /* Restart threads back to what they were trying to do back when we
5397 paused them for an in-line step-over. The EVENT_THREAD thread is
5398 ignored. */
5400 static void
5402 {
5405 /* In case the instruction just stepped spawned a new thread. */
5409 {
5411 {
5414 "infrun: restart threads: "
5418 }
5421 {
5424 "infrun: restart threads: "
5428 }
5431 {
5438 }
5441 {
5444 "infrun: restart threads: "
5449 }
5453 {
5456 "infrun: restart threads: "
5461 }
5465 /* If some thread needs to start a step-over at this point, it
5466 should still be in the step-over queue, and thus skipped
5467 above. */
5469 {
5471 "thread [%s] needs a step-over, but not in "
5474 }
5477 {
5483 }
5484 else
5485 {
5496 }
5497 }
5498 }
5500 /* Callback for iterate_over_threads. Find a resumed thread that has
5501 a pending waitstatus. */
5503 static int
5506 {
5509 }
5511 /* Called when we get an event that may finish an in-line or
5512 out-of-line (displaced stepping) step-over started previously.
5513 Return true if the event is processed and we should go back to the
5514 event loop; false if the caller should continue processing the
5515 event. */
5517 static int
5519 {
5528 {
5529 /* If we're stepping over a breakpoint with all threads locked,
5530 then only the thread that was stepped should be reporting
5531 back an event. */
5535 }
5540 /* Start a new step-over in another thread if there's one that
5541 needs it. */
5544 /* If we were stepping over a breakpoint before, and haven't started
5545 a new in-line step-over sequence, then restart all other threads
5546 (except the event thread). We can't do this in all-stop, as then
5547 e.g., we wouldn't be able to issue any other remote packet until
5548 these other threads stop. */
5550 {
5553 /* If we only have threads with pending statuses, the restart
5554 below won't restart any thread and so nothing re-inserts the
5555 breakpoint we just stepped over. But we need it inserted
5556 when we later process the pending events, otherwise if
5557 another thread has a pending event for this breakpoint too,
5558 we'd discard its event (because the breakpoint that
5559 originally caused the event was no longer inserted). */
5565 /* If we have events pending, go through handle_inferior_event
5566 again, picking up a pending event at random. This avoids
5567 thread starvation. */
5569 /* But not if we just stepped over a watchpoint in order to let
5570 the instruction execute so we can evaluate its expression.
5571 The set of watchpoints that triggered is recorded in the
5572 breakpoint objects themselves (see bp->watchpoint_triggered).
5573 If we processed another event first, that other event could
5574 clobber this info. */
5579 NULL);
5581 {
5586 {
5588 "infrun: found resumed threads with "
5590 }
5594 /* Record the event thread's event for later. */
5596 /* This was cleared early, by handle_inferior_event. Set it
5597 so this pending event is considered by
5598 do_target_wait. */
5607 {
5609 "infrun: saved stop_pc=%s for %s "
5615 }
5617 /* This in-line step-over finished; clear this so we won't
5618 start a new one. This is what handle_signal_stop would
5619 do, if we returned false. */
5622 /* Wake up the event loop again. */
5627 }
5628 }
5631 }
5633 /* Come here when the program has stopped with a signal. */
5635 static void
5637 {
5648 /* Do we need to clean up the state of a thread that has
5649 completed a displaced single-step? (Doing so usually affects
5650 the PC, so do it here, before we set stop_pc.) */
5654 /* If we either finished a single-step or hit a breakpoint, but
5655 the user wanted this thread to be stopped, pretend we got a
5656 SIG0 (generic unsignaled stop). */
5665 {
5676 {
5677 CORE_ADDR addr;
5685 else
5688 }
5689 }
5691 /* This is originated from start_remote(), start_inferior() and
5692 shared libraries hook functions. */
5695 {
5702 }
5704 /* This originates from attach_command(). We need to overwrite
5705 the stop_signal here, because some kernels don't ignore a
5706 SIGSTOP in a subsequent ptrace(PTRACE_CONT,SIGSTOP) call.
5707 See more comments in inferior.h. On the other hand, if we
5708 get a non-SIGSTOP, report it to the user - assume the backend
5709 will handle the SIGSTOP if it should show up later.
5711 Also consider that the attach is complete when we see a
5712 SIGTRAP. Some systems (e.g. Windows), and stubs supporting
5713 target extended-remote report it instead of a SIGSTOP
5714 (e.g. gdbserver). We already rely on SIGTRAP being our
5715 signal, so this is no exception.
5717 Also consider that the attach is complete when we see a
5718 GDB_SIGNAL_0. In non-stop mode, GDB will explicitly tell
5719 the target to stop all threads of the inferior, in case the
5720 low level attach operation doesn't stop them implicitly. If
5721 they weren't stopped implicitly, then the stub will report a
5722 GDB_SIGNAL_0, meaning: stopped for no particular reason
5723 other than GDB's request. */
5728 {
5733 }
5735 /* See if something interesting happened to the non-current thread. If
5736 so, then switch to that thread. */
5738 {
5746 }
5748 /* At this point, get hold of the now-current thread's frame. */
5752 /* Pull the single step breakpoints out of the target. */
5754 {
5756 CORE_ADDR pc;
5763 /* However, before doing so, if this single-step breakpoint was
5764 actually for another thread, set this thread up for moving
5765 past it. */
5768 {
5770 {
5772 {
5774 "infrun: [%s] hit another thread's "
5777 }
5779 }
5780 }
5781 else
5782 {
5784 {
5786 "infrun: [%s] hit its "
5789 }
5790 }
5791 }
5798 else
5801 /* If necessary, step over this watchpoint. We'll be back to display
5802 it in a moment. */
5804 && (target_have_steppable_watchpoint
5806 {
5807 /* At this point, we are stopped at an instruction which has
5808 attempted to write to a piece of memory under control of
5809 a watchpoint. The instruction hasn't actually executed
5810 yet. If we were to evaluate the watchpoint expression
5811 now, we would get the old value, and therefore no change
5812 would seem to have occurred.
5814 In order to make watchpoints work `right', we really need
5815 to complete the memory write, and then evaluate the
5816 watchpoint expression. We do this by single-stepping the
5817 target.
5819 It may not be necessary to disable the watchpoint to step over
5820 it. For example, the PA can (with some kernel cooperation)
5821 single step over a watchpoint without disabling the watchpoint.
5823 It is far more common to need to disable a watchpoint to step
5824 the inferior over it. If we have non-steppable watchpoints,
5825 we must disable the current watchpoint; it's simplest to
5826 disable all watchpoints.
5828 Any breakpoint at PC must also be stepped over -- if there's
5829 one, it will have already triggered before the watchpoint
5830 triggered, and we either already reported it to the user, or
5831 it didn't cause a stop and we called keep_going. In either
5832 case, if there was a breakpoint at PC, we must be trying to
5833 step past it. */
5837 }
5847 /* Hide inlined functions starting here, unless we just performed stepi or
5848 nexti. After stepi and nexti, always show the innermost frame (not any
5849 inline function call sites). */
5851 {
5855 /* skip_inline_frames is expensive, so we avoid it if we can
5856 determine that the address is one where functions cannot have
5857 been inlined. This improves performance with inferiors that
5858 load a lot of shared libraries, because the solib event
5859 breakpoint is defined as the address of a function (i.e. not
5860 inline). Note that we have to check the previous PC as well
5861 as the current one to catch cases when we have just
5862 single-stepped off a breakpoint prior to reinstating it.
5863 Note that we're assuming that the code we single-step to is
5864 not inline, but that's not definitive: there's nothing
5865 preventing the event breakpoint function from containing
5866 inlined code, and the single-step ending up there. If the
5867 user had set a breakpoint on that inlined code, the missing
5868 skip_inline_frames call would break things. Fortunately
5869 that's an extremely unlikely scenario. */
5878 {
5884 /* Re-fetch current thread's frame in case that invalidated
5885 the frame cache. */
5888 }
5889 }
5895 {
5896 /* We're trying to step off a breakpoint. Turns out that we're
5897 also on an instruction that needs to be stepped multiple
5898 times before it's been fully executing. E.g., architectures
5899 with a delay slot. It needs to be stepped twice, once for
5900 the instruction and once for the delay slot. */
5901 int step_through_delay
5908 {
5909 /* The user issued a continue when stopped at a breakpoint.
5910 Set up for another trap and get out of here. */
5914 }
5916 {
5917 /* The user issued a step when stopped at a breakpoint.
5918 Maybe we should stop, maybe we should not - the delay
5919 slot *might* correspond to a line of source. In any
5920 case, don't decide that here, just set
5921 ecs->stepping_over_breakpoint, making sure we
5922 single-step again before breakpoints are re-inserted. */
5924 }
5925 }
5927 /* See if there is a breakpoint/watchpoint/catchpoint/etc. that
5928 handles this event. */
5934 /* Following in case break condition called a
5935 function. */
5938 /* This is where we handle "moribund" watchpoints. Unlike
5939 software breakpoints traps, hardware watchpoint traps are
5940 always distinguishable from random traps. If no high-level
5941 watchpoint is associated with the reported stop data address
5942 anymore, then the bpstat does not explain the signal ---
5943 simply make sure to ignore it if `stopped_by_watchpoint' is
5944 set. */
5949 GDB_SIGNAL_TRAP)
5952 "infrun: no user watchpoint explains "
5955 /* NOTE: cagney/2003-03-29: These checks for a random signal
5956 at one stage in the past included checks for an inferior
5957 function call's call dummy's return breakpoint. The original
5958 comment, that went with the test, read:
5960 ``End of a stack dummy. Some systems (e.g. Sony news) give
5961 another signal besides SIGTRAP, so check here as well as
5962 above.''
5964 If someone ever tries to get call dummys on a
5965 non-executable stack to work (where the target would stop
5966 with something like a SIGSEGV), then those tests might need
5967 to be re-instated. Given, however, that the tests were only
5968 enabled when momentary breakpoints were not being used, I
5969 suspect that it won't be the case.
5971 NOTE: kettenis/2004-02-05: Indeed such checks don't seem to
5972 be necessary for call dummies on a non-executable stack on
5973 SPARC. */
5975 /* See if the breakpoints module can explain the signal. */
5976 random_signal
5980 /* Maybe this was a trap for a software breakpoint that has since
5981 been removed. */
5983 {
5986 {
5990 /* Re-adjust PC to what the program would see if GDB was not
5991 debugging it. */
5995 {
5997 restore_operation_disable;
6000 restore_operation_disable.emplace
6005 }
6006 }
6007 else
6008 {
6009 /* A delayed software breakpoint event. Ignore the trap. */
6012 "infrun: delayed software breakpoint "
6015 }
6016 }
6018 /* Maybe this was a trap for a hardware breakpoint/watchpoint that
6019 has since been removed. */
6021 {
6022 /* A delayed hardware breakpoint event. Ignore the trap. */
6025 "infrun: delayed hardware breakpoint/watchpoint "
6028 }
6030 /* If not, perhaps stepping/nexting can. */
6035 /* Perhaps the thread hit a single-step breakpoint of _another_
6036 thread. Single-step breakpoints are transparent to the
6037 breakpoints module. */
6041 /* No? Perhaps we got a moribund watchpoint. */
6045 /* Always stop if the user explicitly requested this thread to
6046 remain stopped. */
6048 {
6052 }
6054 /* For the program's own signals, act according to
6055 the signal handling tables. */
6058 {
6059 /* Signal not for debugging purposes. */
6069 /* Always stop on signals if we're either just gaining control
6070 of the program, or the user explicitly requested this thread
6071 to remain stopped. */
6076 {
6079 }
6081 /* Notify observers the signal has "handle print" set. Note we
6082 returned early above if stopping; normal_stop handles the
6083 printing in that case. */
6085 {
6086 /* The signal table tells us to print about this signal. */
6090 }
6092 /* Clear the signal if it should not be passed. */
6099 {
6100 /* We were just starting a new sequence, attempting to
6101 single-step off of a breakpoint and expecting a SIGTRAP.
6102 Instead this signal arrives. This signal will take us out
6103 of the stepping range so GDB needs to remember to, when
6104 the signal handler returns, resume stepping off that
6105 breakpoint. */
6106 /* To simplify things, "continue" is forced to use the same
6107 code paths as single-step - set a breakpoint at the
6108 signal return address and then, once hit, step off that
6109 breakpoint. */
6112 "infrun: signal arrived while stepping over "
6117 /* Reset trap_expected to ensure breakpoints are re-inserted. */
6120 /* If we were nexting/stepping some other thread, switch to
6121 it, so that we don't continue it, losing control. */
6125 }
6134 {
6135 /* The inferior is about to take a signal that will take it
6136 out of the single step range. Set a breakpoint at the
6137 current PC (which is presumably where the signal handler
6138 will eventually return) and then allow the inferior to
6139 run free.
6141 Note that this is only needed for a signal delivered
6142 while in the single-step range. Nested signals aren't a
6143 problem as they eventually all return. */
6146 "infrun: signal may take us out of "
6152 /* Reset trap_expected to ensure breakpoints are re-inserted. */
6156 }
6158 /* Note: step_resume_breakpoint may be non-NULL. This occures
6159 when either there's a nested signal, or when there's a
6160 pending signal enabled just as the signal handler returns
6161 (leaving the inferior at the step-resume-breakpoint without
6162 actually executing it). Either way continue until the
6163 breakpoint is really hit. */
6166 {
6172 }
6174 }
6177 }
6179 /* Come here when we've got some debug event / signal we can explain
6180 (IOW, not a random signal), and test whether it should cause a
6181 stop, or whether we should resume the inferior (transparently).
6182 E.g., could be a breakpoint whose condition evaluates false; we
6183 could be still stepping within the line; etc. */
6185 static void
6187 {
6191 CORE_ADDR jmp_buf_pc;
6194 /* Handle cases caused by hitting a breakpoint. */
6202 {
6204 }
6206 /* A few breakpoint types have callbacks associated (e.g.,
6207 bp_jit_event). Run them now. */
6210 /* If we hit an internal event that triggers symbol changes, the
6211 current frame will be invalidated within bpstat_what (e.g., if we
6212 hit an internal solib event). Re-fetch it. */
6217 {
6219 /* If we hit the breakpoint at longjmp while stepping, we
6220 install a momentary breakpoint at the target of the
6221 jmp_buf. */
6230 {
6233 /* If we set the longjmp breakpoint via a SystemTap probe,
6234 then use it to extract the arguments. The destination PC
6235 is the third argument to the probe. */
6238 {
6241 }
6245 {
6248 "infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME "
6252 }
6254 /* Insert a breakpoint at resume address. */
6256 }
6257 else
6263 {
6266 /* There are several cases to consider.
6268 1. The initiating frame no longer exists. In this case we
6269 must stop, because the exception or longjmp has gone too
6270 far.
6272 2. The initiating frame exists, and is the same as the
6273 current frame. We stop, because the exception or longjmp
6274 has been caught.
6276 3. The initiating frame exists and is different from the
6277 current frame. This means the exception or longjmp has
6278 been caught beneath the initiating frame, so keep going.
6280 4. longjmp breakpoint has been placed just to protect
6281 against stale dummy frames and user is not interested in
6282 stopping around longjmps. */
6293 {
6297 {
6298 /* Case 4. */
6301 }
6302 }
6307 {
6308 struct frame_id current_id
6312 {
6313 /* Case 2. Fall through. */
6314 }
6315 else
6316 {
6317 /* Case 3. */
6320 }
6321 }
6323 /* For Cases 1 and 2, remove the step-resume breakpoint, if it
6324 exists. */
6328 }
6335 /* Still need to check other stuff, at least the case where we
6336 are stepping and step out of the right range. */
6346 {
6349 /* We are finishing a function in reverse, and just hit the
6350 step-resume breakpoint at the start address of the
6351 function, and we're almost there -- just need to back up
6352 by one more single-step, which should take us back to the
6353 function call. */
6357 }
6361 {
6362 /* We are stepping over a function call in reverse, and just
6363 hit the step-resume breakpoint at the start address of
6364 the function. Go back to single-stepping, which should
6365 take us back to the function call. */
6369 }
6377 /* Assume the thread stopped for a breapoint. We'll still check
6378 whether a/the breakpoint is there when the thread is next
6379 resumed. */
6390 /* Assume the thread stopped for a breapoint. We'll still check
6391 whether a/the breakpoint is there when the thread is next
6392 resumed. */
6403 {
6404 /* Back when the step-resume breakpoint was inserted, we
6405 were trying to single-step off a breakpoint. Go back to
6406 doing that. */
6411 }
6416 }
6418 /* If we stepped a permanent breakpoint and we had a high priority
6419 step-resume breakpoint for the address we stepped, but we didn't
6420 hit it, then we must have stepped into the signal handler. The
6421 step-resume was only necessary to catch the case of _not_
6422 stepping into the handler, so delete it, and fall through to
6423 checking whether the step finished. */
6425 {
6433 {
6436 "infrun: stepped permanent breakpoint, stopped in "
6440 }
6441 }
6443 /* We come here if we hit a breakpoint but should not stop for it.
6444 Possibly we also were stepping and should stop for that. So fall
6445 through and test for stepping. But, if not stepping, do not
6446 stop. */
6448 /* In all-stop mode, if we're currently stepping but have stopped in
6449 some other thread, we need to switch back to the stepped thread. */
6454 {
6459 /* Having a step-resume breakpoint overrides anything
6460 else having to do with stepping commands until
6461 that breakpoint is reached. */
6464 }
6467 {
6470 /* Likewise if we aren't even stepping. */
6473 }
6475 /* Re-fetch current thread's frame in case the code above caused
6476 the frame cache to be re-initialized, making our FRAME variable
6477 a dangling pointer. */
6482 /* If stepping through a line, keep going if still within it.
6484 Note that step_range_end is the address of the first instruction
6485 beyond the step range, and NOT the address of the last instruction
6486 within it!
6488 Note also that during reverse execution, we may be stepping
6489 through a function epilogue and therefore must detect when
6490 the current-frame changes in the middle of a line. */
6497 {
6499 fprintf_unfiltered
6504 /* Tentatively re-enable range stepping; `resume' disables it if
6505 necessary (e.g., if we're stepping over a breakpoint or we
6506 have software watchpoints). */
6509 /* When stepping backward, stop at beginning of line range
6510 (unless it's the function entry point, in which case
6511 keep going back to the call point). */
6517 else
6521 }
6523 /* We stepped out of the stepping range. */
6525 /* If we are stepping at the source level and entered the runtime
6526 loader dynamic symbol resolution code...
6528 EXEC_FORWARD: we keep on single stepping until we exit the run
6529 time loader code and reach the callee's address.
6531 EXEC_REVERSE: we've already executed the callee (backward), and
6532 the runtime loader code is handled just like any other
6533 undebuggable function call. Now we need only keep stepping
6534 backward through the trampoline code, and that's handled further
6535 down, so there is nothing for us to do here. */
6540 {
6541 CORE_ADDR pc_after_resolver =
6550 {
6551 /* Set up a step-resume breakpoint at the address
6552 indicated by SKIP_SOLIB_RESOLVER. */
6553 symtab_and_line sr_sal;
6559 }
6563 }
6565 /* Step through an indirect branch thunk. */
6569 {
6575 }
6581 {
6585 /* The inferior, while doing a "step" or "next", has ended up in
6586 a signal trampoline (either by a signal being delivered or by
6587 the signal handler returning). Just single-step until the
6588 inferior leaves the trampoline (either by calling the handler
6589 or returning). */
6592 }
6594 /* If we're in the return path from a shared library trampoline,
6595 we want to proceed through the trampoline when stepping. */
6596 /* macro/2012-04-25: This needs to come before the subroutine
6597 call check below as on some targets return trampolines look
6598 like subroutine calls (MIPS16 return thunks). */
6603 {
6604 /* Determine where this trampoline returns. */
6606 CORE_ADDR real_stop_pc
6613 /* Only proceed through if we know where it's going. */
6615 {
6616 /* And put the step-breakpoint there and go until there. */
6617 symtab_and_line sr_sal;
6622 /* Do not specify what the fp should be when we stop since
6623 on some machines the prologue is where the new fp value
6624 is established. */
6628 /* Restart without fiddling with the step ranges or
6629 other state. */
6632 }
6633 }
6635 /* Check for subroutine calls. The check for the current frame
6636 equalling the step ID is not necessary - the check of the
6637 previous frame's ID is sufficient - but it is a common case and
6638 cheaper than checking the previous frame's ID.
6640 NOTE: frame_id_eq will never report two invalid frame IDs as
6641 being equal, so to get into this block, both the current and
6642 previous frame must have valid frame IDs. */
6643 /* The outer_frame_id check is a heuristic to detect stepping
6644 through startup code. If we step over an instruction which
6645 sets the stack pointer from an invalid value to a valid value,
6646 we may detect that as a subroutine call from the mythical
6647 "outermost" function. This could be fixed by marking
6648 outermost frames as !stack_p,code_p,special_p. Then the
6649 initial outermost frame, before sp was valid, would
6650 have code_addr == &_start. See the comment in frame_id_eq
6651 for more. */
6657 outer_frame_id)
6660 {
6662 CORE_ADDR real_stop_pc;
6668 {
6669 /* I presume that step_over_calls is only 0 when we're
6670 supposed to be stepping at the assembly language level
6671 ("stepi"). Just stop. */
6672 /* And this works the same backward as frontward. MVS */
6675 }
6677 /* Reverse stepping through solib trampolines. */
6684 {
6685 /* Any solib trampoline code can be handled in reverse
6686 by simply continuing to single-step. We have already
6687 executed the solib function (backwards), and a few
6688 steps will take us back through the trampoline to the
6689 caller. */
6692 }
6695 {
6696 /* We're doing a "next".
6698 Normal (forward) execution: set a breakpoint at the
6699 callee's return address (the address at which the caller
6700 will resume).
6702 Reverse (backward) execution. set the step-resume
6703 breakpoint at the start of the function that we just
6704 stepped into (backwards), and continue to there. When we
6705 get there, we'll need to single-step back to the caller. */
6708 {
6709 /* If we're already at the start of the function, we've either
6710 just stepped backward into a single instruction function,
6711 or stepped back out of a signal handler to the first instruction
6712 of the function. Just keep going, which will single-step back
6713 to the caller. */
6715 {
6716 /* Normal function call return (static or dynamic). */
6717 symtab_and_line sr_sal;
6722 }
6723 }
6724 else
6729 }
6731 /* If we are in a function call trampoline (a stub between the
6732 calling routine and the real function), locate the real
6733 function. That's what tells us (a) whether we want to step
6734 into it at all, and (b) what prologue we want to run to the
6735 end of, if we do step into it. */
6743 {
6744 symtab_and_line sr_sal;
6752 }
6754 /* If we have line number information for the function we are
6755 thinking of stepping into and the function isn't on the skip
6756 list, step into it.
6758 If there are several symtabs at that PC (e.g. with include
6759 files), just want to know whether *any* of them have line
6760 numbers. find_pc_line handles this. */
6761 {
6767 tmp_sal))
6768 {
6771 else
6774 }
6775 }
6777 /* If we have no line number and the step-stop-if-no-debug is
6778 set, we stop the step so that the user has a chance to switch
6779 in assembly mode. */
6782 {
6785 }
6788 {
6789 /* If we're already at the start of the function, we've either just
6790 stepped backward into a single instruction function without line
6791 number info, or stepped back out of a signal handler to the first
6792 instruction of the function without line number info. Just keep
6793 going, which will single-step back to the caller. */
6795 {
6796 /* Set a breakpoint at callee's start address.
6797 From there we can step once and be back in the caller. */
6798 symtab_and_line sr_sal;
6803 }
6804 }
6805 else
6806 /* Set a breakpoint at callee's return address (the address
6807 at which the caller will resume). */
6812 }
6814 /* Reverse stepping through solib trampolines. */
6818 {
6824 {
6825 /* Any solib trampoline code can be handled in reverse
6826 by simply continuing to single-step. We have already
6827 executed the solib function (backwards), and a few
6828 steps will take us back through the trampoline to the
6829 caller. */
6832 }
6834 {
6835 /* Stepped backward into the solib dynsym resolver.
6836 Set a breakpoint at its start and continue, then
6837 one more step will take us out. */
6838 symtab_and_line sr_sal;
6845 }
6846 }
6850 /* NOTE: tausq/2004-05-24: This if block used to be done before all
6851 the trampoline processing logic, however, there are some trampolines
6852 that have no names, so we should do trampoline handling first. */
6856 {
6861 /* The inferior just stepped into, or returned to, an
6862 undebuggable function (where there is no debugging information
6863 and no line number corresponding to the address where the
6864 inferior stopped). Since we want to skip this kind of code,
6865 we keep going until the inferior returns from this
6866 function - unless the user has asked us not to (via
6867 set step-mode) or we no longer know how to get back
6868 to the call site. */
6871 {
6872 /* If we have no line number and the step-stop-if-no-debug
6873 is set, we stop the step so that the user has a chance to
6874 switch in assembly mode. */
6877 }
6878 else
6879 {
6880 /* Set a breakpoint at callee's return address (the address
6881 at which the caller will resume). */
6885 }
6886 }
6889 {
6890 /* It is stepi or nexti. We always want to stop stepping after
6891 one instruction. */
6896 }
6899 {
6900 /* We have no line number information. That means to stop
6901 stepping (does this always happen right after one instruction,
6902 when we do "s" in a function with no line numbers,
6903 or can this happen as a result of a return or longjmp?). */
6908 }
6910 /* Look for "calls" to inlined functions, part one. If the inline
6911 frame machinery detected some skipped call sites, we have entered
6912 a new inline function. */
6917 {
6925 {
6926 /* For "step", we're going to stop. But if the call site
6927 for this inlined function is on the same source line as
6928 we were previously stepping, go down into the function
6929 first. Otherwise stop at the call site. */
6937 }
6938 else
6939 {
6940 /* For "next", we should stop at the call site if it is on a
6941 different source line. Otherwise continue through the
6942 inlined function. */
6946 else
6949 }
6950 }
6952 /* Look for "calls" to inlined functions, part two. If we are still
6953 in the same real function we were stepping through, but we have
6954 to go further up to find the exact frame ID, we are stepping
6955 through a more inlined call beyond its call site. */
6962 {
6969 else
6972 }
6977 {
6978 /* We are at the start of a different line. So stop. Note that
6979 we don't stop if we step into the middle of a different line.
6980 That is said to make things like for (;;) statements work
6981 better. */
6987 }
6989 /* We aren't done stepping.
6991 Optimize by setting the stepping range to the line.
6992 (We might not be in the original line, but if we entered a
6993 new line in mid-statement, we continue stepping. This makes
6994 things like for(;;) statements work better.) */
7004 }
7006 /* In all-stop mode, if we're currently stepping but have stopped in
7007 some other thread, we may need to switch back to the stepped
7008 thread. Returns true we set the inferior running, false if we left
7009 it stopped (and the event needs further processing). */
7011 static int
7013 {
7015 {
7019 /* If any thread is blocked on some internal breakpoint, and we
7020 simply need to step over that breakpoint to get it going
7021 again, do that first. */
7023 /* However, if we see an event for the stepping thread, then we
7024 know all other threads have been moved past their breakpoints
7025 already. Let the caller check whether the step is finished,
7026 etc., before deciding to move it past a breakpoint. */
7030 /* Check if the current thread is blocked on an incomplete
7031 step-over, interrupted by a random signal. */
7034 {
7036 {
7040 }
7043 }
7045 /* Check if the current thread is blocked by a single-step
7046 breakpoint of another thread. */
7048 {
7050 {
7052 "infrun: need to step [%s] over single-step "
7055 }
7058 }
7060 /* If this thread needs yet another step-over (e.g., stepping
7061 through a delay slot), do it first before moving on to
7062 another thread. */
7064 {
7066 {
7070 }
7073 }
7075 /* If scheduler locking applies even if not stepping, there's no
7076 need to walk over threads. Above we've checked whether the
7077 current thread is stepping. If some other thread not the
7078 event thread is stepping, then it must be that scheduler
7079 locking is not in effect. */
7083 /* Otherwise, we no longer expect a trap in the current thread.
7084 Clear the trap_expected flag before switching back -- this is
7085 what keep_going does as well, if we call it. */
7088 /* Likewise, clear the signal if it should not be passed. */
7092 /* Do all pending step-overs before actually proceeding with
7093 step/next/etc. */
7095 {
7098 }
7100 /* Look for the stepping/nexting thread. */
7104 {
7105 /* Ignore threads of processes the caller is not
7106 resuming. */
7111 /* When stepping over a breakpoint, we lock all threads
7112 except the one that needs to move past the breakpoint.
7113 If a non-event thread has this set, the "incomplete
7114 step-over" check above should have caught it earlier. */
7116 {
7118 "[%s] has inconsistent state: "
7122 }
7124 /* Did we find the stepping thread? */
7126 {
7127 /* Yep. There should only one though. */
7130 /* The event thread is handled at the top, before we
7131 enter this loop. */
7134 /* If some thread other than the event thread is
7135 stepping, then scheduler locking can't be in effect,
7136 otherwise we wouldn't have resumed the current event
7137 thread in the first place. */
7141 }
7142 }
7145 {
7151 {
7154 }
7155 }
7156 }
7159 }
7161 /* Set a previously stepped thread back to stepping. Returns true on
7162 success, false if the resume is not possible (e.g., the thread
7163 vanished). */
7165 static int
7167 {
7172 /* If the stepping thread exited, then don't try to switch back and
7173 resume it, which could fail in several different ways depending
7174 on the target. Instead, just keep going.
7176 We can find a stepping dead thread in the thread list in two
7177 cases:
7179 - The target supports thread exit events, and when the target
7180 tries to delete the thread from the thread list, inferior_ptid
7181 pointed at the exiting thread. In such case, calling
7182 delete_thread does not really remove the thread from the list;
7183 instead, the thread is left listed, with 'exited' state.
7185 - The target's debug interface does not support thread exit
7186 events, and so we have no idea whatsoever if the previously
7187 stepping thread is still alive. For that reason, we need to
7188 synchronously query the target now. */
7191 {
7194 "infrun: not resuming previously "
7199 }
7211 /* If the PC of the thread we were trying to single-step has
7212 changed, then that thread has trapped or been signaled, but the
7213 event has not been reported to GDB yet. Re-poll the target
7214 looking for this particular thread's event (i.e. temporarily
7215 enable schedlock) by:
7217 - setting a break at the current PC
7218 - resuming that particular thread, only (by setting trap
7219 expected)
7221 This prevents us continuously moving the single-step breakpoint
7222 forward, one instruction at a time, overstepping. */
7225 {
7226 ptid_t resume_ptid;
7234 /* Clear the info of the previous step-over, as it's no longer
7235 valid (if the thread was trying to step over a breakpoint, it
7236 has already succeeded). It's what keep_going would do too,
7237 if we called it. Do this before trying to insert the sss
7238 breakpoint, otherwise if we were previously trying to step
7239 over this exact address in another thread, the breakpoint is
7240 skipped. */
7251 }
7252 else
7253 {
7259 }
7261 }
7263 /* Is thread TP in the middle of (software or hardware)
7264 single-stepping? (Note the result of this function must never be
7265 passed directly as target_resume's STEP parameter.) */
7267 static int
7269 {
7275 }
7277 /* Inferior has stepped into a subroutine call with source code that
7278 we should not step over. Do step to the first line of code in
7279 it. */
7281 static void
7284 {
7287 compunit_symtab *cust
7290 ecs->stop_func_start
7294 /* Use the step_resume_break to step until the end of the prologue,
7295 even if that involves jumps (as it seems to on the vax under
7296 4.2). */
7297 /* If the prologue ends in the middle of a source line, continue to
7298 the end of that source line (if it is still within the function).
7299 Otherwise, just go to end of prologue. */
7305 /* Architectures which require breakpoint adjustment might not be able
7306 to place a breakpoint at the computed address. If so, the test
7307 ``ecs->stop_func_start == stop_pc'' will never succeed. Adjust
7308 ecs->stop_func_start to an address at which a breakpoint may be
7309 legitimately placed.
7311 Note: kevinb/2004-01-19: On FR-V, if this adjustment is not
7312 made, GDB will enter an infinite loop when stepping through
7313 optimized code consisting of VLIW instructions which contain
7314 subinstructions corresponding to different source lines. On
7315 FR-V, it's not permitted to place a breakpoint on any but the
7316 first subinstruction of a VLIW instruction. When a breakpoint is
7317 set, GDB will adjust the breakpoint address to the beginning of
7318 the VLIW instruction. Thus, we need to make the corresponding
7319 adjustment here when computing the stop address. */
7322 {
7323 ecs->stop_func_start
7326 }
7329 {
7330 /* We are already there: stop now. */
7333 }
7334 else
7335 {
7336 /* Put the step-breakpoint there and go until there. */
7337 symtab_and_line sr_sal;
7342 /* Do not specify what the fp should be when we stop since on
7343 some machines the prologue is where the new fp value is
7344 established. */
7347 /* And make sure stepping stops right away then. */
7350 }
7352 }
7354 /* Inferior has stepped backward into a subroutine call with source
7355 code that we should not step over. Do step to the beginning of the
7356 last line of code in it. */
7358 static void
7361 {
7369 ecs->stop_func_start
7374 /* OK, we're just going to keep stepping here. */
7376 {
7377 /* We're there already. Just stop stepping now. */
7379 }
7380 else
7381 {
7382 /* Else just reset the step range and keep going.
7383 No step-resume breakpoint, they don't work for
7384 epilogues, which can have multiple entry paths. */
7388 }
7390 }
7392 /* Insert a "step-resume breakpoint" at SR_SAL with frame ID SR_ID.
7393 This is used to both functions and to skip over code. */
7395 static void
7400 {
7401 /* There should never be more than one step-resume or longjmp-resume
7402 breakpoint per thread, so we should never be setting a new
7403 step_resume_breakpoint when one is already active. */
7414 }
7416 void
7420 {
7423 bp_step_resume);
7424 }
7426 /* Insert a "high-priority step-resume breakpoint" at RETURN_FRAME.pc.
7427 This is used to skip a potential signal handler.
7429 This is called with the interrupted function's frame. The signal
7430 handler, when it returns, will resume the interrupted function at
7431 RETURN_FRAME.pc. */
7433 static void
7435 {
7440 symtab_and_line sr_sal;
7447 bp_hp_step_resume);
7448 }
7450 /* Insert a "step-resume breakpoint" at the previous frame's PC. This
7451 is used to skip a function after stepping into it (for "next" or if
7452 the called function has no debugging information).
7454 The current function has almost always been reached by single
7455 stepping a call or return instruction. NEXT_FRAME belongs to the
7456 current function, and the breakpoint will be set at the caller's
7457 resume address.
7459 This is a separate function rather than reusing
7460 insert_hp_step_resume_breakpoint_at_frame in order to avoid
7461 get_prev_frame, which may stop prematurely (see the implementation
7462 of frame_unwind_caller_id for an example). */
7464 static void
7466 {
7467 /* We shouldn't have gotten here if we don't know where the call site
7468 is. */
7473 symtab_and_line sr_sal;
7481 }
7483 /* Insert a "longjmp-resume" breakpoint at PC. This is used to set a
7484 new breakpoint at the target of a jmp_buf. The handling of
7485 longjmp-resume uses the same mechanisms used for handling
7486 "step-resume" breakpoints. */
7488 static void
7490 {
7491 /* There should never be more than one longjmp-resume breakpoint per
7492 thread, so we should never be setting a new
7493 longjmp_resume_breakpoint when one is already active. */
7503 }
7505 /* Insert an exception resume breakpoint. TP is the thread throwing
7506 the exception. The block B is the block of the unwinder debug hook
7507 function. FRAME is the frame corresponding to the call to this
7508 function. SYM is the symbol of the function argument holding the
7509 target PC of the exception. */
7511 static void
7516 {
7517 TRY
7518 {
7521 CORE_ADDR handler;
7527 /* If the value was optimized out, revert to the old behavior. */
7529 {
7538 handler,
7541 /* set_momentary_breakpoint_at_pc invalidates FRAME. */
7546 }
7547 }
7549 {
7550 /* We want to ignore errors here. */
7551 }
7552 END_CATCH
7553 }
7555 /* A helper for check_exception_resume that sets an
7556 exception-breakpoint based on a SystemTap probe. */
7558 static void
7562 {
7564 CORE_ADDR handler;
7577 handler));
7583 }
7585 /* This is called when an exception has been intercepted. Check to
7586 see whether the exception's destination is of interest, and if so,
7587 set an exception resume breakpoint there. */
7589 static void
7592 {
7596 /* First see if this exception unwinding breakpoint was set via a
7597 SystemTap probe point. If so, the probe has two arguments: the
7598 CFA and the HANDLER. We ignore the CFA, extract the handler, and
7599 set a breakpoint there. */
7602 {
7605 }
7611 TRY
7612 {
7618 /* The exception breakpoint is a thread-specific breakpoint on
7619 the unwinder's debug hook, declared as:
7621 void _Unwind_DebugHook (void *cfa, void *handler);
7623 The CFA argument indicates the frame to which control is
7624 about to be transferred. HANDLER is the destination PC.
7626 We ignore the CFA and set a temporary breakpoint at HANDLER.
7627 This is not extremely efficient but it avoids issues in gdb
7628 with computing the DWARF CFA, and it also works even in weird
7629 cases such as throwing an exception from inside a signal
7630 handler. */
7634 {
7640 else
7641 {
7645 }
7646 }
7647 }
7649 {
7650 }
7651 END_CATCH
7652 }
7654 static void
7656 {
7660 /* Let callers know we don't want to wait for the inferior anymore. */
7663 /* If all-stop, but the target is always in non-stop mode, stop all
7664 threads now that we're presenting the stop to the user. */
7667 }
7669 /* Like keep_going, but passes the signal to the inferior, even if the
7670 signal is set to nopass. */
7672 static void
7674 {
7678 /* Save the pc before execution, to compare with pc after stop. */
7683 {
7688 "infrun: %s has trap_expected set, "
7692 /* We haven't yet gotten our trap, and either: intercepted a
7693 non-signal event (e.g., a fork); or took a signal which we
7694 are supposed to pass through to the inferior. Simply
7695 continue. */
7697 }
7699 {
7700 /* Another thread is stepping over a breakpoint in-line. If
7701 this thread needs a step-over too, queue the request. In
7702 either case, this resume must be deferred for later. */
7707 {
7710 "infrun: step-over already in progress: "
7714 }
7715 else
7716 {
7719 "infrun: step-over in progress: "
7722 }
7723 }
7724 else
7725 {
7729 step_over_what step_what;
7731 /* Either the trap was not expected, but we are continuing
7732 anyway (if we got a signal, the user asked it be passed to
7733 the child)
7734 -- or --
7735 We got our expected trap, but decided we should resume from
7736 it.
7738 We're going to run this baby now!
7740 Note that insert_breakpoints won't try to re-insert
7741 already inserted breakpoints. Therefore, we don't
7742 care if breakpoints were already inserted, or not. */
7744 /* If we need to step over a breakpoint, and we're not using
7745 displaced stepping to do so, insert all breakpoints
7746 (watchpoints, etc.) but the one we're stepping over, step one
7747 instruction, and then re-insert the breakpoint when that step
7748 is finished. */
7756 /* We can't use displaced stepping if we need to step past a
7757 watchpoint. The instruction copied to the scratch pad would
7758 still trigger the watchpoint. */
7761 {
7765 }
7769 /* If we now need to do an in-line step-over, we need to stop
7770 all other threads. Note this must be done before
7771 insert_breakpoints below, because that removes the breakpoint
7772 we're about to step over, otherwise other threads could miss
7773 it. */
7777 /* Stop stepping if inserting breakpoints fails. */
7778 TRY
7779 {
7781 }
7783 {
7788 }
7789 END_CATCH
7794 }
7797 }
7799 /* Called when we should continue running the inferior, because the
7800 current event doesn't cause a user visible stop. This does the
7801 resuming part; waiting for the next event is done elsewhere. */
7803 static void
7805 {
7813 }
7815 /* This function normally comes after a resume, before
7816 handle_inferior_event exits. It takes care of any last bits of
7817 housekeeping, and sets the all-important wait_some_more flag. */
7819 static void
7821 {
7829 }
7831 /* We are done with the step range of a step/next/si/ni command.
7832 Called once for each n of a "step n" operation. */
7834 static void
7836 {
7839 }
7841 /* Several print_*_reason functions to print why the inferior has stopped.
7842 We always print something when the inferior exits, or receives a signal.
7843 The rest of the cases are dealt with later on in normal_stop and
7844 print_it_typical. Ideally there should be a call to one of these
7845 print_*_reason functions functions from handle_inferior_event each time
7846 stop_waiting is called.
7848 Note that we don't call these directly, instead we delegate that to
7849 the interpreters, through observers. Interpreters then call these
7850 with whatever uiout is right. */
7852 void
7854 {
7855 /* For CLI-like interpreters, print nothing. */
7858 {
7861 }
7862 }
7864 void
7866 {
7869 uiout->field_string
7883 }
7885 void
7887 {
7893 {
7903 }
7904 else
7905 {
7907 uiout->field_string
7914 }
7915 }
7917 /* Some targets/architectures can do extra processing/display of
7918 segmentation faults. E.g., Intel MPX boundary faults.
7919 Call the architecture dependent function to handle the fault. */
7921 static void
7923 {
7929 }
7931 void
7933 {
7939 ;
7941 {
7949 {
7953 }
7954 }
7955 else
7960 else
7961 {
7965 uiout->field_string
7977 }
7979 }
7981 void
7983 {
7985 }
7987 /* Print current location without a level number, if we have changed
7988 functions or hit a breakpoint. Print source line if we have one.
7989 bpstat_print contains the logic deciding in detail what to print,
7990 based on the event(s) that just occurred. */
7992 static void
7994 {
8002 {
8004 /* FIXME: cagney/2002-12-01: Given that a frame ID does (or
8005 should) carry around the function and does (or should) use
8006 that when doing a frame comparison. */
8012 {
8013 /* Finished step, just print source line. */
8015 }
8016 else
8017 {
8018 /* Print location and source line. */
8020 }
8023 /* Print location and source line. */
8030 /* Something bogus. */
8036 }
8038 /* The behavior of this routine with respect to the source
8039 flag is:
8040 SRC_LINE: Print only source line
8041 LOCATION: Print only location
8042 SRC_AND_LOC: Print location and source line. */
8045 }
8047 /* See infrun.h. */
8049 void
8051 {
8053 ptid_t last_ptid;
8058 {
8063 /* Display the auto-display expressions. */
8065 }
8070 {
8076 }
8077 }
8079 /* See infrun.h. */
8081 void
8083 {
8085 {
8087 {
8092 }
8093 }
8094 }
8096 /* The execution context that just caused a normal stop. */
8098 struct stop_context
8099 {
8107 /* The stop ID. */
8108 ULONGEST stop_id;
8110 /* The event PTID. */
8112 ptid_t ptid;
8114 /* If stopp for a thread event, this is the thread that caused the
8115 stop. */
8118 /* The inferior that caused the stop. */
8120 };
8122 /* Initializes a new stop context. If stopped for a thread event, this
8123 takes a strong reference to the thread. */
8126 {
8132 {
8133 /* Take a strong reference so that the thread can't be deleted
8134 yet. */
8137 }
8138 else
8140 }
8142 /* Release a stop context previously created with save_stop_context.
8143 Releases the strong reference to the thread as well. */
8146 {
8149 }
8151 /* Return true if the current context no longer matches the saved stop
8152 context. */
8154 bool
8156 {
8166 }
8168 /* See infrun.h. */
8170 int
8172 {
8174 ptid_t last_ptid;
8180 /* If an exception is thrown from this point on, make sure to
8181 propagate GDB's knowledge of the executing state to the
8182 frontend/user running state. A QUIT is an easy exception to see
8183 here, so do this before any filtered output. */
8191 {
8192 /* On some targets, we may still have live threads in the
8193 inferior when we get a process exit event. E.g., for
8194 "checkpoint", when the current checkpoint/fork exits,
8195 linux-fork.c automatically switches to another fork from
8196 within target_mourn_inferior. */
8199 }
8203 /* As we're presenting a stop, and potentially removing breakpoints,
8204 update the thread list so we can tell whether there are threads
8205 running on the target. With target remote, for example, we can
8206 only learn about new threads when we explicitly update the thread
8207 list. Do this before notifying the interpreters about signal
8208 stops, end of stepping ranges, etc., so that the "new thread"
8209 output is emitted before e.g., "Program received signal FOO",
8210 instead of after. */
8216 /* As with the notification of thread events, we want to delay
8217 notifying the user that we've switched thread context until
8218 the inferior actually stops.
8220 There's no point in saying anything if the inferior has exited.
8221 Note that SIGNALLED here means "exited with a signal", not
8222 "received a signal".
8224 Also skip saying anything in non-stop mode. In that mode, as we
8225 don't want GDB to switch threads behind the user's back, to avoid
8226 races where the user is typing a command to apply to thread x,
8227 but GDB switches to thread y before the user finishes entering
8228 the command, fetch_inferior_event installs a cleanup to restore
8229 the current thread back to the thread the user had selected right
8230 after this event is handled, so we're not really switching, only
8231 informing of a stop. */
8234 && target_has_execution
8238 {
8240 {
8245 }
8247 }
8250 {
8253 {
8256 }
8257 }
8259 /* Note: this depends on the update_thread_list call above. */
8262 /* If an auto-display called a function and that got a signal,
8263 delete that auto-display to avoid an infinite recursion. */
8269 {
8271 }
8273 /* Let the user/frontend see the threads as stopped. */
8276 /* Select innermost stack frame - i.e., current frame is frame 0,
8277 and current location is based on that. Handle the case where the
8278 dummy call is returning after being stopped. E.g. the dummy call
8279 previously hit a breakpoint. (If the dummy call returns
8280 normally, we won't reach here.) Do this before the stop hook is
8281 run, so that it doesn't get to see the temporary dummy frame,
8282 which is not where we'll present the stop. */
8284 {
8286 {
8287 /* Pop the empty frame that contains the stack dummy. This
8288 also restores inferior state prior to the call (struct
8289 infcall_suspend_state). */
8294 /* frame_pop calls reinit_frame_cache as the last thing it
8295 does which means there's now no selected frame. */
8296 }
8300 /* Set the current source location. */
8302 }
8304 /* Look up the hook_stop and run it (CLI internally handles problem
8305 of stop_command's pre-hook not existing). */
8307 {
8308 stop_context saved_context;
8310 TRY
8311 {
8313 }
8315 {
8318 }
8319 END_CATCH
8321 /* If the stop hook resumes the target, then there's no point in
8322 trying to notify about the previous stop; its context is
8323 gone. Likewise if the command switches thread or inferior --
8324 the observers would print a stop for the wrong
8325 thread/inferior. */
8328 }
8330 /* Notify observers about the stop. This is where the interpreters
8331 print the stop event. */
8334 stop_print_frame);
8335 else
8341 {
8344 /* Delete the breakpoint we stopped at, if it wants to be deleted.
8345 Delete any breakpoint that is to be deleted at the next stop. */
8347 }
8349 /* Try to get rid of automatically added inferiors that are no
8350 longer needed. Keeping those around slows down things linearly.
8351 Note that this never removes the current inferior. */
8355 }
8356 \f
8357 int
8359 {
8361 }
8363 int
8365 {
8367 }
8369 int
8371 {
8373 }
8375 static void
8377 {
8379 {
8384 }
8390 }
8392 int
8394 {
8400 }
8402 int
8404 {
8410 }
8412 int
8414 {
8420 }
8422 /* Update the global 'signal_catch' from INFO and notify the
8423 target. */
8425 void
8427 {
8434 }
8436 static void
8438 {
8441 }
8443 static void
8445 {
8458 }
8460 /* Specify how various signals in the inferior should be handled. */
8462 static void
8464 {
8473 {
8475 }
8477 /* Allocate and zero an array of flags for which signals to handle. */
8483 /* Break the command line up into args. */
8487 /* Walk through the args, looking for signal oursigs, signal names, and
8488 actions. Signal numbers and signal names may be interspersed with
8489 actions, with the actions being performed for all signals cumulatively
8490 specified. Signal ranges can be specified as <LOW>-<HIGH>. */
8493 {
8496 {;
8497 }
8502 {
8503 /* Apply action to all signals except those used by the
8504 debugger. Silently skip those. */
8508 }
8510 {
8513 }
8515 {
8517 }
8519 {
8521 }
8523 {
8525 }
8527 {
8529 }
8531 {
8533 }
8535 {
8538 }
8540 {
8542 }
8544 {
8545 /* It is numeric. The numeric signal refers to our own
8546 internal signal numbering from target.h, not to host/target
8547 signal number. This is a feature; users really should be
8548 using symbolic names anyway, and the common ones like
8549 SIGHUP, SIGINT, SIGALRM, etc. will work right anyway. */
8554 {
8557 }
8559 {
8560 /* Bet he didn't figure we'd think of this case... */
8562 }
8563 }
8564 else
8565 {
8568 {
8570 }
8571 else
8572 {
8573 /* Not a number and not a recognized flag word => complain. */
8575 }
8576 }
8578 /* If any signal numbers or symbol names were found, set flags for
8579 which signals to apply actions to. */
8582 {
8584 {
8588 {
8592 {
8594 }
8595 else
8596 {
8599 }
8600 }
8605 /* Make sure that "all" doesn't print these. */
8610 }
8611 }
8612 }
8616 {
8622 {
8623 /* Show the results. */
8628 }
8631 }
8632 }
8634 /* Complete the "handle" command. */
8636 static void
8640 {
8642 {
8652 NULL,
8653 };
8657 }
8659 enum gdb_signal
8661 {
8666 }
8668 /* Print current contents of the tables set by the handle command.
8669 It is possible we should just be printing signals actually used
8670 by the current target (but for things to work right when switching
8671 targets, all signals should be in the signal tables). */
8673 static void
8675 {
8681 {
8682 /* First see if this is a symbol name. */
8685 {
8686 /* No, try numeric. */
8687 oursig =
8689 }
8692 }
8695 /* These ugly casts brought to you by the native VAX compiler. */
8699 {
8700 QUIT;
8705 }
8709 }
8711 /* The $_siginfo convenience variable is a bit special. We don't know
8712 for sure the type of the value until we actually have a chance to
8713 fetch the data. The type can change depending on gdbarch, so it is
8714 also dependent on which thread you have selected.
8716 1. making $_siginfo be an internalvar that creates a new value on
8717 access.
8719 2. making the value of $_siginfo be an lval_computed value. */
8721 /* This function implements the lval_computed support for reading a
8722 $_siginfo value. */
8724 static void
8726 {
8727 LONGEST transferred;
8729 /* If we can access registers, so can we access $_siginfo. Likewise
8730 vice versa. */
8733 transferred =
8735 NULL,
8742 }
8744 /* This function implements the lval_computed support for writing a
8745 $_siginfo value. */
8747 static void
8749 {
8750 LONGEST transferred;
8752 /* If we can access registers, so can we access $_siginfo. Likewise
8753 vice versa. */
8757 TARGET_OBJECT_SIGNAL_INFO,
8758 NULL,
8765 }
8768 {
8769 siginfo_value_read,
8770 siginfo_value_write
8771 };
8773 /* Return a new value with the correct type for the siginfo object of
8774 the current thread using architecture GDBARCH. Return a void value
8775 if there's no object available. */
8780 {
8784 {
8788 }
8791 }
8793 \f
8794 /* infcall_suspend_state contains state about the program itself like its
8795 registers and any signal it received when it last stopped.
8796 This state must be restored regardless of how the inferior function call
8797 ends (either successfully, or after it hits a breakpoint or signal)
8798 if the program is to properly continue where it left off. */
8800 struct infcall_suspend_state
8801 {
8804 /* Other fields: */
8807 /* Format of SIGINFO_DATA or NULL if it is not present. */
8810 /* The inferior format depends on SIGINFO_GDBARCH and it has a length of
8811 TYPE_LENGTH (gdbarch_get_siginfo_type ()). For different gdbarch the
8812 content would be invalid. */
8814 };
8816 infcall_suspend_state_up
8818 {
8825 {
8833 {
8834 /* Errors ignored. */
8836 }
8837 }
8842 {
8845 }
8849 /* run_inferior_call will not use the signal due to its `proceed' call with
8850 GDB_SIGNAL_0 anyway. */
8856 }
8858 /* Restore inferior session state to INF_STATE. */
8860 void
8862 {
8870 {
8873 /* Errors ignored. */
8876 }
8878 /* The inferior can be gone if the user types "print exit(0)"
8879 (and perhaps other times). */
8881 /* NB: The register write goes through to the target. */
8885 }
8887 void
8889 {
8891 }
8893 readonly_detached_regcache *
8895 {
8897 }
8899 /* infcall_control_state contains state regarding gdb's control of the
8900 inferior itself like stepping control. It also contains session state like
8901 the user's currently selected frame. */
8903 struct infcall_control_state
8904 {
8908 /* Other fields: */
8912 /* ID if the selected frame when the inferior function call was made. */
8914 };
8916 /* Save all of the information associated with the inferior<==>gdb
8917 connection. */
8919 infcall_control_state_up
8921 {
8932 /* Save original bpstat chain to INF_STATUS; replace it in TP with copy of
8933 chain. If caller's caller is walking the chain, they'll be happier if we
8934 hand them back the original chain when restore_infcall_control_state is
8935 called. */
8938 /* Other fields: */
8945 }
8947 static void
8949 {
8952 /* If inf_status->selected_frame_id is NULL, there was no previously
8953 selected frame. */
8955 {
8958 }
8961 }
8963 /* Restore inferior session state to INF_STATUS. */
8965 void
8967 {
8978 /* Handle the bpstat_copy of the chain. */
8984 /* Other fields: */
8989 {
8990 /* The point of the try/catch is that if the stack is clobbered,
8991 walking the stack might encounter a garbage pointer and
8992 error() trying to dereference it. */
8993 TRY
8994 {
8996 }
8998 {
9001 /* Error in restoring the selected frame. Select the
9002 innermost frame. */
9004 }
9005 END_CATCH
9006 }
9009 }
9011 void
9013 {
9022 /* See save_infcall_control_state for info on stop_bpstat. */
9026 }
9027 \f
9028 /* See infrun.h. */
9030 void
9032 {
9035 }
9036 \f
9038 /* User interface for reverse debugging:
9039 Set exec-direction / show exec-direction commands
9040 (returns error unless target implements to_set_exec_direction method). */
9047 exec_forward,
9048 exec_reverse,
9049 NULL
9050 };
9052 static void
9055 {
9057 {
9062 }
9063 else
9064 {
9067 }
9068 }
9070 static void
9073 {
9085 }
9086 }
9088 static void
9091 {
9094 }
9096 /* Implementation of `siginfo' variable. */
9099 {
9100 siginfo_make_value,
9101 NULL,
9102 NULL
9103 };
9105 /* Callback for infrun's target events source. This is marked when a
9106 thread has a pending status to process. */
9108 static void
9110 {
9112 }
9114 void
9116 {
9121 /* Register extra event sources in the event loop. */
9122 infrun_async_inferior_event_token
9167 NULL,
9168 show_debug_infrun,
9176 NULL,
9177 show_debug_displaced,
9195 set_non_stop,
9196 show_non_stop,
9207 {
9212 }
9214 /* Signals caused by debugger's own actions should not be given to
9215 the program afterwards.
9217 Do not deliver GDB_SIGNAL_TRAP by default, except when the user
9218 explicitly specifies that it should be delivered to the target
9219 program. Typically, that would occur when a user is debugging a
9220 target monitor on a simulator: the target monitor sets a
9221 breakpoint; the simulator encounters this breakpoint and halts
9222 the simulation handing control to GDB; GDB, noting that the stop
9223 address doesn't map to any known breakpoint, returns control back
9224 to the simulator; the simulator then delivers the hardware
9225 equivalent of a GDB_SIGNAL_TRAP to the program being
9226 debugged. */
9230 /* Signals that are not errors should not normally enter the debugger. */
9250 /* These signals are used internally by user-level thread
9251 implementations. (See signal(5) on Solaris.) Like the above
9252 signals, a healthy program receives and handles them as part of
9253 its normal operation. */
9263 /* Update cached state. */
9273 set_stop_on_solib_events,
9274 show_stop_on_solib_events,
9278 follow_fork_mode_kind_names,
9287 NULL,
9288 show_follow_fork_mode_string,
9292 follow_exec_mode_names,
9311 NULL,
9312 show_follow_exec_mode_string,
9327 show_scheduler_mode,
9338 NULL,
9339 show_schedule_multiple,
9348 NULL,
9349 show_step_stop_if_no_debug,
9362 NULL,
9363 show_can_use_displaced_stepping,
9374 /* Set/show detach-on-fork: user-settable mode. */
9382 /* Set/show disable address space randomization mode. */
9395 /* ptid initializations */
9404 /* Explicitly create without lookup, since that tries to create a
9405 value with a void typed value, and when we get here, gdbarch
9406 isn't initialized yet. At this point, we're quite sure there
9407 isn't another convenience variable of the same name. */
9418 set_observer_mode,
9419 show_observer_mode,
9422 }