| blob | 4164a003c263f94594b4a1d84d206c421caefb9e |
1 /* Target-struct-independent code to start (run) and stop an inferior
2 process.
4 Copyright (C) 1986-2015 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>
64 /* Prototypes for local functions */
101 /* When set, stop the 'step' command if we enter a function which has
102 no line number information. The normal behavior is that we step
103 over such function. */
105 static void
108 {
110 }
112 /* In asynchronous mode, but simulating synchronous execution. */
116 /* proceed and normal_stop use this to notify the user when the
117 inferior stopped in a different thread than it had been running
118 in. */
122 /* If set (default for legacy reasons), when following a fork, GDB
123 will detach from one of the fork branches, child or parent.
124 Exactly which branch is detached depends on 'set follow-fork-mode'
125 setting. */
130 static void
133 {
135 }
138 static void
141 {
143 }
146 /* Support for disabling address space randomization. */
150 static void
153 {
158 value);
159 else
163 }
165 static void
168 {
173 }
175 /* User interface for non-stop mode. */
180 static void
183 {
185 {
188 }
191 }
193 static void
196 {
199 value);
200 }
202 /* "Observer mode" is somewhat like a more extreme version of
203 non-stop, in which all GDB operations that might affect the
204 target's execution have been disabled. */
209 static void
212 {
214 {
217 }
225 /* We can insert fast tracepoints in or out of observer mode,
226 but enable them if we're going into this mode. */
232 /* Going *into* observer mode we must force non-stop, then
233 going out we leave it that way. */
235 {
238 }
243 }
245 static void
248 {
250 }
252 /* This updates the value of observer mode based on changes in
253 permissions. Note that we are deliberately ignoring the values of
254 may-write-registers and may-write-memory, since the user may have
255 reason to enable these during a session, for instance to turn on a
256 debugging-related global. */
258 void
260 {
263 newval = (!may_insert_breakpoints
264 && !may_insert_tracepoints
265 && may_insert_fast_tracepoints
266 && !may_stop
269 /* Let the user know if things change. */
275 }
277 /* Tables of how to react to signals; the user sets them. */
283 /* Table of signals that are registered with "catch signal". A
284 non-zero entry indicates that the signal is caught by some "catch
285 signal" command. This has size GDB_SIGNAL_LAST, to accommodate all
286 signals. */
289 /* Table of signals that the target may silently handle.
290 This is automatically determined from the flags above,
291 and simply cached here. */
294 #define SET_SIGS(nsigs,sigs,flags) \
295 do { \
296 int signum = (nsigs); \
297 while (signum-- > 0) \
298 if ((sigs)[signum]) \
299 (flags)[signum] = 1; \
300 } while (0)
302 #define UNSET_SIGS(nsigs,sigs,flags) \
303 do { \
304 int signum = (nsigs); \
305 while (signum-- > 0) \
306 if ((sigs)[signum]) \
307 (flags)[signum] = 0; \
308 } while (0)
310 /* Update the target's copy of SIGNAL_PROGRAM. The sole purpose of
311 this function is to avoid exporting `signal_program'. */
313 void
315 {
317 }
319 /* Value to pass to target_resume() to cause all threads to resume. */
321 #define RESUME_ALL minus_one_ptid
323 /* Command list pointer for the "stop" placeholder. */
327 /* Nonzero if we want to give control to the user when we're notified
328 of shared library events by the dynamic linker. */
331 /* Enable or disable optional shared library event breakpoints
332 as appropriate when the above flag is changed. */
334 static void
336 {
338 }
340 static void
343 {
345 value);
346 }
348 /* Nonzero means expecting a trace trap
349 and should stop the inferior and return silently when it happens. */
353 /* Save register contents here when executing a "finish" command or are
354 about to pop a stack dummy frame, if-and-only-if proceed_to_finish is set.
355 Thus this contains the return value from the called function (assuming
356 values are returned in a register). */
360 /* Nonzero after stop if current stack frame should be printed. */
364 /* This is a cached copy of the pid/waitstatus of the last event
365 returned by target_wait()/deprecated_target_wait_hook(). This
366 information is returned by get_last_target_status(). */
378 follow_fork_mode_child,
379 follow_fork_mode_parent,
380 NULL
381 };
384 static void
387 {
391 value);
392 }
393 \f
395 /* Handle changes to the inferior list based on the type of fork,
396 which process is being followed, and whether the other process
397 should be detached. On entry inferior_ptid must be the ptid of
398 the fork parent. At return inferior_ptid is the ptid of the
399 followed inferior. */
401 static int
403 {
416 {
417 /* The parent stays blocked inside the vfork syscall until the
418 child execs or exits. If we don't let the child run, then
419 the parent stays blocked. If we're telling the parent to run
420 in the foreground, the user will not be able to ctrl-c to get
421 back the terminal, effectively hanging the debug session. */
426 /* FIXME output string > 80 columns. */
428 }
431 {
432 /* Detach new forked process? */
434 {
437 /* Before detaching from the child, remove all breakpoints
438 from it. If we forked, then this has already been taken
439 care of by infrun.c. If we vforked however, any
440 breakpoint inserted in the parent is visible in the
441 child, even those added while stopped in a vfork
442 catchpoint. This will remove the breakpoints from the
443 parent also, but they'll be reinserted below. */
445 {
446 /* Keep breakpoints list in sync. */
448 }
451 {
457 }
458 }
459 else
460 {
464 /* Add process to GDB's tables. */
480 /* If this is a vfork child, then the address-space is
481 shared with the parent. */
483 {
487 /* The parent will be frozen until the child is done
488 with the shared region. Keep track of the
489 parent. */
494 }
495 else
496 {
503 /* Let the shared library layer (e.g., solib-svr4) learn
504 about this new process, relocate the cloned exec, pull
505 in shared libraries, and install the solib event
506 breakpoint. If a "cloned-VM" event was propagated
507 better throughout the core, this wouldn't be
508 required. */
510 }
513 }
516 {
521 /* If we detached from the child, then we have to be careful
522 to not insert breakpoints in the parent until the child
523 is done with the shared memory region. However, if we're
524 staying attached to the child, then we can and should
525 insert breakpoints, so that we can debug it. A
526 subsequent child exec or exit is enough to know when does
527 the child stops using the parent's address space. */
530 }
531 }
532 else
533 {
534 /* Follow the child. */
539 {
546 }
548 /* Add the new inferior first, so that the target_detach below
549 doesn't unpush the target. */
561 /* If we're vforking, we want to hold on to the parent until the
562 child exits or execs. At child exec or exit time we can
563 remove the old breakpoints from the parent and detach or
564 resume debugging it. Otherwise, detach the parent now; we'll
565 want to reuse it's program/address spaces, but we can't set
566 them to the child before removing breakpoints from the
567 parent, otherwise, the breakpoints module could decide to
568 remove breakpoints from the wrong process (since they'd be
569 assigned to the same address space). */
572 {
580 }
582 {
584 {
590 }
593 }
595 /* Note that the detach above makes PARENT_INF dangling. */
597 /* Add the child thread to the appropriate lists, and switch to
598 this new thread, before cloning the program space, and
599 informing the solib layer about this new process. */
604 /* If this is a vfork child, then the address-space is shared
605 with the parent. If we detached from the parent, then we can
606 reuse the parent's program/address spaces. */
608 {
611 }
612 else
613 {
621 /* Let the shared library layer (e.g., solib-svr4) learn
622 about this new process, relocate the cloned exec, pull in
623 shared libraries, and install the solib event breakpoint.
624 If a "cloned-VM" event was propagated better throughout
625 the core, this wouldn't be required. */
627 }
628 }
631 }
633 /* Tell the target to follow the fork we're stopped at. Returns true
634 if the inferior should be resumed; false, if the target for some
635 reason decided it's best not to resume. */
637 static int
639 {
644 /* Copy user stepping state to the new inferior thread. FIXME: the
645 followed fork child thread should have a copy of most of the
646 parent thread structure's run control related fields, not just these.
647 Initialized to avoid "may be used uninitialized" warnings from gcc. */
656 {
657 ptid_t wait_ptid;
660 /* Get the last target status returned by target_wait(). */
663 /* If not stopped at a fork event, then there's nothing else to
664 do. */
669 /* Check if we switched over from WAIT_PTID, since the event was
670 reported. */
673 {
674 /* We did. Switch back to WAIT_PTID thread, to tell the
675 target to follow it (in either direction). We'll
676 afterwards refuse to resume, and inform the user what
677 happened. */
680 }
681 }
685 /* If there were any forks/vforks that were caught and are now to be
686 followed, then do so now. */
688 {
691 {
694 /* If the user did a next/step, etc, over a fork call,
695 preserve the stepping state in the fork child. */
697 {
698 step_resume_breakpoint = clone_momentary_breakpoint
703 exception_resume_breakpoint
707 /* For now, delete the parent's sr breakpoint, otherwise,
708 parent/child sr breakpoints are considered duplicates,
709 and the child version will not be installed. Remove
710 this when the breakpoints module becomes aware of
711 inferiors and address spaces. */
718 }
723 /* Set up inferior(s) as specified by the caller, and tell the
724 target to do whatever is necessary to follow either parent
725 or child. */
727 {
728 /* Target refused to follow, or there's some other reason
729 we shouldn't resume. */
731 }
732 else
733 {
734 /* This pending follow fork event is now handled, one way
735 or another. The previous selected thread may be gone
736 from the lists by now, but if it is still around, need
737 to clear the pending follow request. */
742 /* This makes sure we don't try to apply the "Switched
743 over from WAIT_PID" logic above. */
746 /* If we followed the child, switch to it... */
748 {
751 /* ... and preserve the stepping state, in case the
752 user was stepping over the fork call. */
754 {
764 }
765 else
766 {
767 /* If we get here, it was because we're trying to
768 resume from a fork catchpoint, but, the user
769 has switched threads away from the thread that
770 forked. In that case, the resume command
771 issued is most likely not applicable to the
772 child, so just warn, and refuse to resume. */
775 }
777 /* Reset breakpoints in the child as appropriate. */
779 }
780 else
782 }
783 }
786 /* Nothing to follow. */
793 }
796 }
798 static void
800 {
803 /* Was there a step_resume breakpoint? (There was if the user
804 did a "next" at the fork() call.) If so, explicitly reset its
805 thread number. Cloned step_resume breakpoints are disabled on
806 creation, so enable it here now that it is associated with the
807 correct thread.
809 step_resumes are a form of bp that are made to be per-thread.
810 Since we created the step_resume bp when the parent process
811 was being debugged, and now are switching to the child process,
812 from the breakpoint package's viewpoint, that's a switch of
813 "threads". We must update the bp's notion of which thread
814 it is for, or it'll be ignored when it triggers. */
817 {
820 }
822 /* Treat exception_resume breakpoints like step_resume breakpoints. */
824 {
827 }
829 /* Reinsert all breakpoints in the child. The user may have set
830 breakpoints after catching the fork, in which case those
831 were never set in the child, but only in the parent. This makes
832 sure the inserted breakpoints match the breakpoint list. */
836 }
838 /* The child has exited or execed: resume threads of the parent the
839 user wanted to be executing. */
841 static int
844 {
852 {
861 }
864 }
866 /* Called whenever we notice an exec or exit event, to handle
867 detaching or resuming a vfork parent. */
869 static void
871 {
875 {
878 /* This exec or exit marks the end of the shared memory region
879 between the parent and the child. If the user wanted to
880 detach from the parent, now is the time. */
883 {
889 /* follow-fork child, detach-on-fork on. */
894 {
895 /* If we're handling a child exit, then inferior_ptid
896 points at the inferior's pid, not to a thread. */
900 }
901 else
904 /* We're letting loose of the parent. */
908 /* We're about to detach from the parent, which implicitly
909 removes breakpoints from its address space. There's a
910 catch here: we want to reuse the spaces for the child,
911 but, parent/child are still sharing the pspace at this
912 point, although the exec in reality makes the kernel give
913 the child a fresh set of new pages. The problem here is
914 that the breakpoints module being unaware of this, would
915 likely chose the child process to write to the parent
916 address space. Swapping the child temporarily away from
917 the spaces has the desired effect. Yes, this is "sort
918 of" a hack. */
926 {
930 {
935 }
936 else
937 {
942 }
943 }
947 /* Put it back. */
952 }
954 {
955 /* We're staying attached to the parent, so, really give the
956 child a new address space. */
964 /* Break the bonds. */
966 }
967 else
968 {
972 /* If this is a vfork child exiting, then the pspace and
973 aspaces were shared with the parent. Since we're
974 reporting the process exit, we'll be mourning all that is
975 found in the address space, and switching to null_ptid,
976 preparing to start a new inferior. But, since we don't
977 want to clobber the parent's address/program spaces, we
978 go ahead and create a new one for this exiting
979 inferior. */
981 /* Switch to null_ptid, so that clone_program_space doesn't want
982 to read the selected frame of a dead process. */
986 /* This inferior is dead, so avoid giving the breakpoints
987 module the option to write through to it (cloning a
988 program space resets breakpoints). */
999 /* Put back inferior_ptid. We'll continue mourning this
1000 inferior. */
1004 /* Break the bonds. */
1006 }
1013 {
1014 /* If the user wanted the parent to be running, let it go
1015 free now. */
1021 resume_parent);
1026 }
1027 }
1028 }
1030 /* Enum strings for "set|show follow-exec-mode". */
1035 {
1036 follow_exec_mode_new,
1037 follow_exec_mode_same,
1038 NULL,
1039 };
1042 static void
1045 {
1047 }
1049 /* EXECD_PATHNAME is assumed to be non-NULL. */
1051 static void
1053 {
1058 /* This is an exec event that we actually wish to pay attention to.
1059 Refresh our symbol table to the newly exec'd program, remove any
1060 momentary bp's, etc.
1062 If there are breakpoints, they aren't really inserted now,
1063 since the exec() transformed our inferior into a fresh set
1064 of instructions.
1066 We want to preserve symbolic breakpoints on the list, since
1067 we have hopes that they can be reset after the new a.out's
1068 symbol table is read.
1070 However, any "raw" breakpoints must be removed from the list
1071 (e.g., the solib bp's), since their address is probably invalid
1072 now.
1074 And, we DON'T want to call delete_breakpoints() here, since
1075 that may write the bp's "shadow contents" (the instruction
1076 value that was overwritten witha TRAP instruction). Since
1077 we now have a new a.out, those shadow contents aren't valid. */
1081 /* The target reports the exec event to the main thread, even if
1082 some other thread does the exec, and even if the main thread was
1083 stopped or already gone. We may still have non-leader threads of
1084 the process on our list. E.g., on targets that don't have thread
1085 exit events (like remote); or on native Linux in non-stop mode if
1086 there were only two threads in the inferior and the non-leader
1087 one is the one that execs (and nothing forces an update of the
1088 thread list up to here). When debugging remotely, it's best to
1089 avoid extra traffic, when possible, so avoid syncing the thread
1090 list with the target, and instead go ahead and delete all threads
1091 of the process but one that reported the event. Note this must
1092 be done before calling update_breakpoints_after_exec, as
1093 otherwise clearing the threads' resources would reference stale
1094 thread breakpoints -- it may have been one of these threads that
1095 stepped across the exec. We could just clear their stepping
1096 states, but as long as we're iterating, might as well delete
1097 them. Deleting them now rather than at the next user-visible
1098 stop provides a nicer sequence of events for user and MI
1099 notifications. */
1104 /* We also need to clear any left over stale state for the
1105 leader/event thread. E.g., if there was any step-resume
1106 breakpoint or similar, it's gone now. We cannot truly
1107 step-to-next statement through an exec(). */
1115 /* The user may have had the main thread held stopped in the
1116 previous image (e.g., schedlock on, or non-stop). Release
1117 it now. */
1122 /* What is this a.out's name? */
1125 execd_pathname);
1127 /* We've followed the inferior through an exec. Therefore, the
1128 inferior has essentially been killed & reborn. */
1135 {
1143 }
1145 /* Reset the shared library package. This ensures that we get a
1146 shlib event when the child reaches "_start", at which point the
1147 dld will have had a chance to initialize the child. */
1148 /* Also, loading a symbol file below may trigger symbol lookups, and
1149 we don't want those to be satisfied by the libraries of the
1150 previous incarnation of this process. */
1154 {
1157 /* The user wants to keep the old inferior and program spaces
1158 around. Create a new fresh one, and switch to it. */
1169 }
1170 else
1171 {
1172 /* The old description may no longer be fit for the new image.
1173 E.g, a 64-bit process exec'ed a 32-bit process. Clear the
1174 old description; we'll read a new one below. No need to do
1175 this on "follow-exec-mode new", as the old inferior stays
1176 around (its description is later cleared/refetched on
1177 restart). */
1179 }
1183 /* That a.out is now the one to use. */
1186 /* SYMFILE_DEFER_BP_RESET is used as the proper displacement for PIE
1187 (Position Independent Executable) main symbol file will get applied by
1188 solib_create_inferior_hook below. breakpoint_re_set would fail to insert
1189 the breakpoints with the zero displacement. */
1199 /* If the target can specify a description, read it. Must do this
1200 after flipping to the new executable (because the target supplied
1201 description must be compatible with the executable's
1202 architecture, and the old executable may e.g., be 32-bit, while
1203 the new one 64-bit), and before anything involving memory or
1204 registers. */
1213 /* Reinsert all breakpoints. (Those which were symbolic have
1214 been reset to the proper address in the new a.out, thanks
1215 to symbol_file_command...). */
1218 /* The next resume of this inferior should bring it to the shlib
1219 startup breakpoints. (If the user had also set bp's on
1220 "main" from the old (parent) process, then they'll auto-
1221 matically get reset there in the new process.). */
1222 }
1224 /* Info about an instruction that is being stepped over. */
1226 struct step_over_info
1227 {
1228 /* If we're stepping past a breakpoint, this is the address space
1229 and address of the instruction the breakpoint is set at. We'll
1230 skip inserting all breakpoints here. Valid iff ASPACE is
1231 non-NULL. */
1233 CORE_ADDR address;
1235 /* The instruction being stepped over triggers a nonsteppable
1236 watchpoint. If true, we'll skip inserting watchpoints. */
1238 };
1240 /* The step-over info of the location that is being stepped over.
1242 Note that with async/breakpoint always-inserted mode, a user might
1243 set a new breakpoint/watchpoint/etc. exactly while a breakpoint is
1244 being stepped over. As setting a new breakpoint inserts all
1245 breakpoints, we need to make sure the breakpoint being stepped over
1246 isn't inserted then. We do that by only clearing the step-over
1247 info when the step-over is actually finished (or aborted).
1249 Presently GDB can only step over one breakpoint at any given time.
1250 Given threads that can't run code in the same address space as the
1251 breakpoint's can't really miss the breakpoint, GDB could be taught
1252 to step-over at most one breakpoint per address space (so this info
1253 could move to the address space object if/when GDB is extended).
1254 The set of breakpoints being stepped over will normally be much
1255 smaller than the set of all breakpoints, so a flag in the
1256 breakpoint location structure would be wasteful. A separate list
1257 also saves complexity and run-time, as otherwise we'd have to go
1258 through all breakpoint locations clearing their flag whenever we
1259 start a new sequence. Similar considerations weigh against storing
1260 this info in the thread object. Plus, not all step overs actually
1261 have breakpoint locations -- e.g., stepping past a single-step
1262 breakpoint, or stepping to complete a non-continuable
1263 watchpoint. */
1266 /* Record the address of the breakpoint/instruction we're currently
1267 stepping over. */
1269 static void
1272 {
1276 }
1278 /* Called when we're not longer stepping over a breakpoint / an
1279 instruction, so all breakpoints are free to be (re)inserted. */
1281 static void
1283 {
1287 }
1289 /* See infrun.h. */
1291 int
1293 CORE_ADDR address)
1294 {
1299 }
1301 /* See infrun.h. */
1303 int
1305 {
1307 }
1309 /* Returns true if step-over info is valid. */
1311 static int
1313 {
1316 }
1318 \f
1319 /* Displaced stepping. */
1321 /* In non-stop debugging mode, we must take special care to manage
1322 breakpoints properly; in particular, the traditional strategy for
1323 stepping a thread past a breakpoint it has hit is unsuitable.
1324 'Displaced stepping' is a tactic for stepping one thread past a
1325 breakpoint it has hit while ensuring that other threads running
1326 concurrently will hit the breakpoint as they should.
1328 The traditional way to step a thread T off a breakpoint in a
1329 multi-threaded program in all-stop mode is as follows:
1331 a0) Initially, all threads are stopped, and breakpoints are not
1332 inserted.
1333 a1) We single-step T, leaving breakpoints uninserted.
1334 a2) We insert breakpoints, and resume all threads.
1336 In non-stop debugging, however, this strategy is unsuitable: we
1337 don't want to have to stop all threads in the system in order to
1338 continue or step T past a breakpoint. Instead, we use displaced
1339 stepping:
1341 n0) Initially, T is stopped, other threads are running, and
1342 breakpoints are inserted.
1343 n1) We copy the instruction "under" the breakpoint to a separate
1344 location, outside the main code stream, making any adjustments
1345 to the instruction, register, and memory state as directed by
1346 T's architecture.
1347 n2) We single-step T over the instruction at its new location.
1348 n3) We adjust the resulting register and memory state as directed
1349 by T's architecture. This includes resetting T's PC to point
1350 back into the main instruction stream.
1351 n4) We resume T.
1353 This approach depends on the following gdbarch methods:
1355 - gdbarch_max_insn_length and gdbarch_displaced_step_location
1356 indicate where to copy the instruction, and how much space must
1357 be reserved there. We use these in step n1.
1359 - gdbarch_displaced_step_copy_insn copies a instruction to a new
1360 address, and makes any necessary adjustments to the instruction,
1361 register contents, and memory. We use this in step n1.
1363 - gdbarch_displaced_step_fixup adjusts registers and memory after
1364 we have successfuly single-stepped the instruction, to yield the
1365 same effect the instruction would have had if we had executed it
1366 at its original address. We use this in step n3.
1368 - gdbarch_displaced_step_free_closure provides cleanup.
1370 The gdbarch_displaced_step_copy_insn and
1371 gdbarch_displaced_step_fixup functions must be written so that
1372 copying an instruction with gdbarch_displaced_step_copy_insn,
1373 single-stepping across the copied instruction, and then applying
1374 gdbarch_displaced_insn_fixup should have the same effects on the
1375 thread's memory and registers as stepping the instruction in place
1376 would have. Exactly which responsibilities fall to the copy and
1377 which fall to the fixup is up to the author of those functions.
1379 See the comments in gdbarch.sh for details.
1381 Note that displaced stepping and software single-step cannot
1382 currently be used in combination, although with some care I think
1383 they could be made to. Software single-step works by placing
1384 breakpoints on all possible subsequent instructions; if the
1385 displaced instruction is a PC-relative jump, those breakpoints
1386 could fall in very strange places --- on pages that aren't
1387 executable, or at addresses that are not proper instruction
1388 boundaries. (We do generally let other threads run while we wait
1389 to hit the software single-step breakpoint, and they might
1390 encounter such a corrupted instruction.) One way to work around
1391 this would be to have gdbarch_displaced_step_copy_insn fully
1392 simulate the effect of PC-relative instructions (and return NULL)
1393 on architectures that use software single-stepping.
1395 In non-stop mode, we can have independent and simultaneous step
1396 requests, so more than one thread may need to simultaneously step
1397 over a breakpoint. The current implementation assumes there is
1398 only one scratch space per process. In this case, we have to
1399 serialize access to the scratch space. If thread A wants to step
1400 over a breakpoint, but we are currently waiting for some other
1401 thread to complete a displaced step, we leave thread A stopped and
1402 place it in the displaced_step_request_queue. Whenever a displaced
1403 step finishes, we pick the next thread in the queue and start a new
1404 displaced step operation on it. See displaced_step_prepare and
1405 displaced_step_fixup for details. */
1407 struct displaced_step_request
1408 {
1409 ptid_t ptid;
1411 };
1413 /* Per-inferior displaced stepping state. */
1414 struct displaced_step_inferior_state
1415 {
1416 /* Pointer to next in linked list. */
1419 /* The process this displaced step state refers to. */
1422 /* A queue of pending displaced stepping requests. One entry per
1423 thread that needs to do a displaced step. */
1426 /* If this is not null_ptid, this is the thread carrying out a
1427 displaced single-step in process PID. This thread's state will
1428 require fixing up once it has completed its step. */
1429 ptid_t step_ptid;
1431 /* The architecture the thread had when we stepped it. */
1434 /* The closure provided gdbarch_displaced_step_copy_insn, to be used
1435 for post-step cleanup. */
1438 /* The address of the original instruction, and the copy we
1439 made. */
1442 /* Saved contents of copy area. */
1444 };
1446 /* The list of states of processes involved in displaced stepping
1447 presently. */
1450 /* Get the displaced stepping state of process PID. */
1454 {
1464 }
1466 /* Return true if process PID has a thread doing a displaced step. */
1468 static int
1470 {
1478 }
1480 /* Add a new displaced stepping state for process PID to the displaced
1481 stepping state list, or return a pointer to an already existing
1482 entry, if it already exists. Never returns NULL. */
1486 {
1501 }
1503 /* If inferior is in displaced stepping, and ADDR equals to starting address
1504 of copy area, return corresponding displaced_step_closure. Otherwise,
1505 return NULL. */
1509 {
1513 /* If checking the mode of displaced instruction in copy area. */
1519 }
1521 /* Remove the displaced stepping state of process PID. */
1523 static void
1525 {
1533 {
1535 {
1539 }
1543 }
1544 }
1546 static void
1548 {
1550 }
1552 /* If ON, and the architecture supports it, GDB will use displaced
1553 stepping to step over breakpoints. If OFF, or if the architecture
1554 doesn't support it, GDB will instead use the traditional
1555 hold-and-step approach. If AUTO (which is the default), GDB will
1556 decide which technique to use to step over breakpoints depending on
1557 which of all-stop or non-stop mode is active --- displaced stepping
1558 in non-stop mode; hold-and-step in all-stop mode. */
1562 static void
1566 {
1572 else
1576 }
1578 /* Return non-zero if displaced stepping can/should be used to step
1579 over breakpoints. */
1581 static int
1583 {
1588 }
1590 /* Clean out any stray displaced stepping state. */
1591 static void
1593 {
1594 /* Indicate that there is no cleanup pending. */
1598 {
1602 }
1603 }
1605 static void
1607 {
1611 }
1613 /* Dump LEN bytes at BUF in hex to FILE, followed by a newline. */
1614 void
1618 {
1624 }
1626 /* Prepare to single-step, using displaced stepping.
1628 Note that we cannot use displaced stepping when we have a signal to
1629 deliver. If we have a signal to deliver and an instruction to step
1630 over, then after the step, there will be no indication from the
1631 target whether the thread entered a signal handler or ignored the
1632 signal and stepped over the instruction successfully --- both cases
1633 result in a simple SIGTRAP. In the first case we mustn't do a
1634 fixup, and in the second case we must --- but we can't tell which.
1635 Comments in the code for 'random signals' in handle_inferior_event
1636 explain how we handle this case instead.
1638 Returns 1 if preparing was successful -- this thread is going to be
1639 stepped now; or 0 if displaced stepping this thread got queued. */
1640 static int
1642 {
1648 ULONGEST len;
1653 /* We should never reach this function if the architecture does not
1654 support displaced stepping. */
1657 /* Disable range stepping while executing in the scratch pad. We
1658 want a single-step even if executing the displaced instruction in
1659 the scratch buffer lands within the stepping range (e.g., a
1660 jump/branch). */
1663 /* We have to displaced step one thread at a time, as we only have
1664 access to a single scratch space per inferior. */
1669 {
1670 /* Already waiting for a displaced step to finish. Defer this
1671 request and place in queue. */
1684 {
1688 ;
1690 }
1691 else
1695 }
1696 else
1697 {
1702 }
1714 /* Save the original contents of the copy area. */
1725 {
1730 len);
1731 };
1736 /* We don't support the fully-simulated case at present. */
1739 /* Save the information we need to fix things up if the step
1740 succeeds. */
1749 /* Resume execution at the copy. */
1761 }
1763 static void
1766 {
1772 }
1774 /* Restore the contents of the copy area for thread PTID. */
1776 static void
1778 ptid_t ptid)
1779 {
1789 }
1791 static void
1793 {
1798 /* Was any thread of this process doing a displaced step? */
1802 /* Was this event for the pid we displaced? */
1811 /* Fixup may need to read memory/registers. Switch to the thread
1812 that we're fixing up. Also, target_stopped_by_watchpoint checks
1813 the current thread. */
1816 /* Did the instruction complete successfully? */
1821 {
1822 /* Fix up the resulting state. */
1828 }
1829 else
1830 {
1831 /* Since the instruction didn't complete, all we can do is
1832 relocate the PC. */
1838 }
1844 /* Are there any pending displaced stepping requests? If so, run
1845 one now. Leave the state object around, since we're likely to
1846 need it again soon. */
1848 {
1850 ptid_t ptid;
1853 CORE_ADDR actual_pc;
1868 {
1879 {
1887 }
1892 else
1895 /* Done, we're stepping a thread. */
1897 }
1898 else
1899 {
1903 /* The breakpoint we were sitting under has since been
1904 removed. */
1907 /* Go back to what we were trying to do. */
1918 /* This request was discarded. See if there's any other
1919 thread waiting for its turn. */
1920 }
1921 }
1922 }
1924 /* Update global variables holding ptids to hold NEW_PTID if they were
1925 holding OLD_PTID. */
1926 static void
1928 {
1936 displaced;
1938 {
1945 }
1946 }
1948 \f
1949 /* Resuming. */
1951 /* Things to clean up if we QUIT out of resume (). */
1952 static void
1954 {
1959 }
1965 schedlock_off,
1966 schedlock_on,
1967 schedlock_step,
1968 NULL
1969 };
1971 static void
1974 {
1978 value);
1979 }
1981 static void
1983 {
1985 {
1988 }
1989 }
1991 /* True if execution commands resume all threads of all processes by
1992 default; otherwise, resume only threads of the current inferior
1993 process. */
1996 /* Try to setup for software single stepping over the specified location.
1997 Return 1 if target_resume() should use hardware single step.
1999 GDBARCH the current gdbarch.
2000 PC the location to step over. */
2002 static int
2004 {
2010 {
2012 }
2014 }
2016 /* See infrun.h. */
2018 ptid_t
2020 {
2021 ptid_t resume_ptid;
2024 {
2025 /* With non-stop mode on, threads are always handled
2026 individually. */
2028 }
2031 {
2032 /* User-settable 'scheduler' mode requires solo thread
2033 resume. */
2035 }
2037 {
2038 /* Resume all threads of the current process (and none of other
2039 processes). */
2041 }
2042 else
2043 {
2044 /* Resume all threads of all processes. */
2046 }
2049 }
2051 /* Wrapper for target_resume, that handles infrun-specific
2052 bookkeeping. */
2054 static void
2056 {
2059 /* Install inferior's terminal modes. */
2062 /* Avoid confusing the next resume, if the next stop/resume
2063 happens to apply to another thread. */
2066 /* Advise target which signals may be handled silently.
2068 If we have removed breakpoints because we are stepping over one
2069 in-line (in any thread), we need to receive all signals to avoid
2070 accidentally skipping a breakpoint during execution of a signal
2071 handler.
2073 Likewise if we're displaced stepping, otherwise a trap for a
2074 breakpoint in a signal handler might be confused with the
2075 displaced step finishing. We don't make the displaced_step_fixup
2076 step distinguish the cases instead, because:
2078 - a backtrace while stopped in the signal handler would show the
2079 scratch pad as frame older than the signal handler, instead of
2080 the real mainline code.
2082 - when the thread is later resumed, the signal handler would
2083 return to the scratch pad area, which would no longer be
2084 valid. */
2088 else
2092 }
2094 /* Resume the inferior, but allow a QUIT. This is useful if the user
2095 wants to interrupt some lengthy single-stepping operation
2096 (for child processes, the SIGINT goes to the inferior, and so
2097 we get a SIGINT random_signal, but for remote debugging and perhaps
2098 other targets, that's not true).
2100 SIG is the signal to give the inferior (zero for none). */
2101 void
2103 {
2110 ptid_t resume_ptid;
2111 /* This represents the user's step vs continue request. When
2112 deciding whether "set scheduler-locking step" applies, it's the
2113 user's intention that counts. */
2115 /* This represents what we'll actually request the target to do.
2116 This can decay from a step to a continue, if e.g., we need to
2117 implement single-stepping with breakpoints (software
2118 single-step). */
2123 QUIT;
2125 /* Depends on stepped_breakpoint. */
2129 {
2130 /* Don't try to single-step a vfork parent that is waiting for
2131 the child to get out of the shared memory region (by exec'ing
2132 or exiting). This is particularly important on software
2133 single-step archs, as the child process would trip on the
2134 software single step breakpoint inserted for the parent
2135 process. Since the parent will not actually execute any
2136 instruction until the child is out of the shared region (such
2137 are vfork's semantics), it is safe to simply continue it.
2138 Eventually, we'll see a TARGET_WAITKIND_VFORK_DONE event for
2139 the parent, and tell it to `keep_going', which automatically
2140 re-sets it stepping. */
2145 }
2149 "infrun: resume (step=%d, signal=%s), "
2156 /* Normally, by the time we reach `resume', the breakpoints are either
2157 removed or inserted, as appropriate. The exception is if we're sitting
2158 at a permanent breakpoint; we need to step over it, but permanent
2159 breakpoints can't be removed. So we have to test for it here. */
2161 {
2163 {
2164 /* We have a signal to pass to the inferior. The resume
2165 may, or may not take us to the signal handler. If this
2166 is a step, we'll need to stop in the signal handler, if
2167 there's one, (if the target supports stepping into
2168 handlers), or in the next mainline instruction, if
2169 there's no handler. If this is a continue, we need to be
2170 sure to run the handler with all breakpoints inserted.
2171 In all cases, set a breakpoint at the current address
2172 (where the handler returns to), and once that breakpoint
2173 is hit, resume skipping the permanent breakpoint. If
2174 that breakpoint isn't hit, then we've stepped into the
2175 signal handler (or hit some other event). We'll delete
2176 the step-resume breakpoint then. */
2180 "infrun: resume: skipping permanent breakpoint, "
2187 {
2188 /* Set a "high-priority" step-resume, as we don't want
2189 user breakpoints at PC to trigger (again) when this
2190 hits. */
2195 }
2198 }
2199 else
2200 {
2201 /* There's no signal to pass, we can go ahead and skip the
2202 permanent breakpoint manually. */
2207 /* Update pc to reflect the new address from which we will
2208 execute instructions. */
2212 {
2213 /* We've already advanced the PC, so the stepping part
2214 is done. Now we need to arrange for a trap to be
2215 reported to handle_inferior_event. Set a breakpoint
2216 at the current PC, and run to it. Don't update
2217 prev_pc, because if we end in
2218 switch_back_to_stepped_thread, we want the "expected
2219 thread advanced also" branch to be taken. IOW, we
2220 don't want this thread to step further from PC
2221 (overstep). */
2230 }
2231 }
2232 }
2234 /* If we have a breakpoint to step over, make sure to do a single
2235 step only. Same if we have software watchpoints. */
2239 /* If enabled, step over breakpoints by executing a copy of the
2240 instruction at a different address.
2242 We can't use displaced stepping when we have a signal to deliver;
2243 the comments for displaced_step_prepare explain why. The
2244 comments in the handle_inferior event for dealing with 'random
2245 signals' explain what we do instead.
2247 We can't use displaced stepping when we are waiting for vfork_done
2248 event, displaced stepping breaks the vfork child similarly as single
2249 step software breakpoint. */
2255 {
2259 {
2260 /* Got placed in displaced stepping queue. Will be resumed
2261 later when all the currently queued displaced stepping
2262 requests finish. The thread is not executing at this
2263 point, and the call to set_executing will be made later.
2264 But we need to call set_running here, since from the
2265 user/frontend's point of view, threads were set running.
2266 Unless we're calling an inferior function, as in that
2267 case we pretend the inferior doesn't run at all. */
2272 }
2274 /* Update pc to reflect the new address from which we will execute
2275 instructions due to displaced stepping. */
2281 }
2283 /* Do we need to do it the hard way, w/temp breakpoints? */
2287 /* Currently, our software single-step implementation leads to different
2288 results than hardware single-stepping in one situation: when stepping
2289 into delivering a signal which has an associated signal handler,
2290 hardware single-step will stop at the first instruction of the handler,
2291 while software single-step will simply skip execution of the handler.
2293 For now, this difference in behavior is accepted since there is no
2294 easy way to actually implement single-stepping into a signal handler
2295 without kernel support.
2297 However, there is one scenario where this difference leads to follow-on
2298 problems: if we're stepping off a breakpoint by removing all breakpoints
2299 and then single-stepping. In this case, the software single-step
2300 behavior means that even if there is a *breakpoint* in the signal
2301 handler, GDB still would not stop.
2303 Fortunately, we can at least fix this particular issue. We detect
2304 here the case where we are about to deliver a signal while software
2305 single-stepping with breakpoints removed. In this situation, we
2306 revert the decisions to remove all breakpoints and insert single-
2307 step breakpoints, and instead we install a step-resume breakpoint
2308 at the current address, deliver the signal without stepping, and
2309 once we arrive back at the step-resume breakpoint, actually step
2310 over the breakpoint we originally wanted to step over. */
2314 {
2315 /* If we have nested signals or a pending signal is delivered
2316 immediately after a handler returns, might might already have
2317 a step-resume breakpoint set on the earlier handler. We cannot
2318 set another step-resume breakpoint; just continue on until the
2319 original breakpoint is hit. */
2321 {
2324 }
2332 }
2334 /* If STEP is set, it's a request to use hardware stepping
2335 facilities. But in that case, we should never
2336 use singlestep breakpoint. */
2339 /* Decide the set of threads to ask the target to resume. Start
2340 by assuming everything will be resumed, than narrow the set
2341 by applying increasingly restricting conditions. */
2344 /* Even if RESUME_PTID is a wildcard, and we end up resuming less
2345 (e.g., we might need to step over a breakpoint), from the
2346 user/frontend's point of view, all threads in RESUME_PTID are now
2347 running. Unless we're calling an inferior function, as in that
2348 case pretend we inferior doesn't run at all. */
2352 /* Maybe resume a single thread after all. */
2355 {
2356 /* We're allowing a thread to run past a breakpoint it has
2357 hit, by single-stepping the thread with the breakpoint
2358 removed. In which case, we need to single-step only this
2359 thread, and keep others stopped, as they can miss this
2360 breakpoint if allowed to run. */
2362 }
2366 {
2367 /* The only case we currently need to step a breakpoint
2368 instruction is when we have a signal to deliver. See
2369 handle_signal_stop where we handle random signals that could
2370 take out us out of the stepping range. Normally, in that
2371 case we end up continuing (instead of stepping) over the
2372 signal handler with a breakpoint at PC, but there are cases
2373 where we should _always_ single-step, even if we have a
2374 step-resume breakpoint, like when a software watchpoint is
2375 set. Assuming single-stepping and delivering a signal at the
2376 same time would takes us to the signal handler, then we could
2377 have removed the breakpoint at PC to step over it. However,
2378 some hardware step targets (like e.g., Mac OS) can't step
2379 into signal handlers, and for those, we need to leave the
2380 breakpoint at PC inserted, as otherwise if the handler
2381 recurses and executes PC again, it'll miss the breakpoint.
2382 So we leave the breakpoint inserted anyway, but we need to
2383 record that we tried to step a breakpoint instruction, so
2384 that adjust_pc_after_break doesn't end up confused. */
2389 /* Most targets can step a breakpoint instruction, thus
2390 executing it normally. But if this one cannot, just
2391 continue and we will hit it anyway. */
2394 }
2400 {
2410 }
2413 {
2414 /* If we're resuming a thread with the PC out of the step
2415 range, then we're doing some nested/finer run control
2416 operation, like stepping the thread out of the dynamic
2417 linker or the displaced stepping scratch pad. We
2418 shouldn't have allowed a range step then. */
2420 }
2424 }
2425 \f
2426 /* Proceeding. */
2428 /* Clear out all variables saying what to do when inferior is continued.
2429 First do this, then set the ones you want, then call `proceed'. */
2431 static void
2433 {
2439 /* If this signal should not be seen by program, give it zero.
2440 Used for debugging signals. */
2461 /* Discard any remaining commands or status from previous stop. */
2463 }
2465 void
2467 {
2469 {
2471 ptid_t resume_ptid;
2475 /* In all-stop mode, delete the per-thread status of all threads
2476 we're about to resume, implicitly and explicitly. */
2478 {
2482 }
2483 }
2486 {
2490 {
2491 /* If in non-stop mode, only delete the per-thread status of
2492 the current thread. */
2494 }
2498 }
2507 {
2510 }
2511 }
2513 /* Returns true if TP is still stopped at a breakpoint that needs
2514 stepping-over in order to make progress. If the breakpoint is gone
2515 meanwhile, we can skip the whole step-over dance. */
2517 static int
2519 {
2521 {
2530 }
2533 }
2535 /* Returns true if scheduler locking applies. STEP indicates whether
2536 we're about to do a step/next-like command to a thread. */
2538 static int
2540 {
2544 }
2546 /* Look a thread other than EXCEPT that has previously reported a
2547 breakpoint event, and thus needs a step-over in order to make
2548 progress. Returns NULL is none is found. */
2552 {
2555 /* With non-stop mode on, threads are always handled individually. */
2560 /* If scheduler locking applies, we can avoid iterating over all
2561 threads. */
2563 {
2569 }
2572 {
2573 /* Ignore the EXCEPT thread. */
2576 /* Ignore threads of processes we're not resuming. */
2583 }
2586 }
2588 /* Basic routine for continuing the program in various fashions.
2590 ADDR is the address to resume at, or -1 for resume where stopped.
2591 SIGGNAL is the signal to give it, or 0 for none,
2592 or -1 for act according to how it stopped.
2593 STEP is nonzero if should trap after one instruction.
2594 -1 means return after that and print nothing.
2595 You should probably set various step_... variables
2596 before calling here, if you are stepping.
2598 You should call clear_proceed_status before calling proceed. */
2600 void
2602 {
2606 CORE_ADDR pc;
2609 /* If we're stopped at a fork/vfork, follow the branch set by the
2610 "set follow-fork-mode" command; otherwise, we'll just proceed
2611 resuming the current thread. */
2613 {
2614 /* The target for some reason decided not to resume. */
2619 }
2621 /* We'll update this if & when we switch to a new thread. */
2630 /* Fill in with reasonable starting values. */
2634 {
2638 /* There is a breakpoint at the address we will resume at,
2639 step one instruction before inserting breakpoints so that
2640 we do not stop right away (and report a second hit at this
2641 breakpoint).
2643 Note, we don't do this in reverse, because we won't
2644 actually be executing the breakpoint insn anyway.
2645 We'll be (un-)executing the previous instruction. */
2650 /* We stepped onto an instruction that needs to be stepped
2651 again before re-inserting the breakpoint, do so. */
2653 }
2654 else
2655 {
2657 }
2662 /* Record the interpreter that issued the execution command that
2663 caused this thread to resume. If the top level interpreter is
2664 MI/async, and the execution command was a CLI command
2665 (next/step/etc.), we'll want to print stop event output to the MI
2666 console channel (the stepped-to line, etc.), as if the user
2667 entered the execution command on a real GDB console. */
2677 /* In non-stop, each thread is handled individually. The context
2678 must already be set to the right thread here. */
2679 ;
2680 else
2681 {
2684 /* In a multi-threaded task we may select another thread and
2685 then continue or step.
2687 But if the old thread was stopped at a breakpoint, it will
2688 immediately cause another breakpoint stop without any
2689 execution (i.e. it will report a breakpoint hit incorrectly).
2690 So we must step over it first.
2692 Look for a thread other than the current (TP) that reported a
2693 breakpoint hit and hasn't been resumed yet since. */
2696 {
2702 /* Store the prev_pc for the stepping thread too, needed by
2703 switch_back_to_stepped_thread. */
2707 }
2708 }
2710 /* If we need to step over a breakpoint, and we're not using
2711 displaced stepping to do so, insert all breakpoints (watchpoints,
2712 etc.) but the one we're stepping over, step one instruction, and
2713 then re-insert the breakpoint when that step is finished. */
2715 {
2720 }
2721 else
2730 /* Make sure that output from GDB appears before output from the
2731 inferior. */
2734 /* Refresh prev_pc value just prior to resuming. This used to be
2735 done in stop_waiting, however, setting prev_pc there did not handle
2736 scenarios such as inferior function calls or returning from
2737 a function via the return command. In those cases, the prev_pc
2738 value was not set properly for subsequent commands. The prev_pc value
2739 is used to initialize the starting line number in the ecs. With an
2740 invalid value, the gdb next command ends up stopping at the position
2741 represented by the next line table entry past our start position.
2742 On platforms that generate one line table entry per line, this
2743 is not a problem. However, on the ia64, the compiler generates
2744 extraneous line table entries that do not increase the line number.
2745 When we issue the gdb next command on the ia64 after an inferior call
2746 or a return command, we often end up a few instructions forward, still
2747 within the original line we started.
2749 An attempt was made to refresh the prev_pc at the same time the
2750 execution_control_state is initialized (for instance, just before
2751 waiting for an inferior event). But this approach did not work
2752 because of platforms that use ptrace, where the pc register cannot
2753 be read unless the inferior is stopped. At that point, we are not
2754 guaranteed the inferior is stopped and so the regcache_read_pc() call
2755 can fail. Setting the prev_pc value here ensures the value is updated
2756 correctly when the inferior is stopped. */
2759 /* Resume inferior. */
2762 /* Wait for it to stop (if not standalone)
2763 and in any case decode why it stopped, and act accordingly. */
2764 /* Do this only if we are not using the event loop, or if the target
2765 does not support asynchronous execution. */
2767 {
2770 }
2771 }
2772 \f
2774 /* Start remote-debugging of a machine over a serial link. */
2776 void
2778 {
2784 /* Always go on waiting for the target, regardless of the mode. */
2785 /* FIXME: cagney/1999-09-23: At present it isn't possible to
2786 indicate to wait_for_inferior that a target should timeout if
2787 nothing is returned (instead of just blocking). Because of this,
2788 targets expecting an immediate response need to, internally, set
2789 things up so that the target_wait() is forced to eventually
2790 timeout. */
2791 /* FIXME: cagney/1999-09-24: It isn't possible for target_open() to
2792 differentiate to its caller what the state of the target is after
2793 the initial open has been performed. Here we're assuming that
2794 the target has stopped. It should be possible to eventually have
2795 target_open() return to the caller an indication that the target
2796 is currently running and GDB state should be set to the same as
2797 for an async run. */
2800 /* Now that the inferior has stopped, do any bookkeeping like
2801 loading shared libraries. We want to do this before normal_stop,
2802 so that the displayed frame is up to date. */
2806 }
2808 /* Initialize static vars when a new inferior begins. */
2810 void
2812 {
2813 /* These are meaningless until the first time through wait_for_inferior. */
2823 /* Discard any skipped inlined frames. */
2825 }
2827 \f
2828 /* Data to be passed around while handling an event. This data is
2829 discarded between events. */
2830 struct execution_control_state
2831 {
2832 ptid_t ptid;
2833 /* The thread that got the event, if this was a thread event; NULL
2834 otherwise. */
2839 CORE_ADDR stop_func_start;
2840 CORE_ADDR stop_func_end;
2844 /* True if the event thread hit the single-step breakpoint of
2845 another thread. Thus the event doesn't cause a stop, the thread
2846 needs to be single-stepped past the single-step breakpoint before
2847 we can switch back to the original stepping thread. */
2849 };
2868 /* Callback for iterate over threads. If the thread is stopped, but
2869 the user/frontend doesn't know about that yet, go through
2870 normal_stop, as if the thread had just stopped now. ARG points at
2871 a ptid. If PTID is MINUS_ONE_PTID, applies to all threads. If
2872 ptid_is_pid(PTID) is true, applies to all threads of the process
2873 pointed at by PTID. Otherwise, apply only to the thread pointed by
2874 PTID. */
2876 static int
2878 {
2887 {
2897 /* Flush target cache before starting to handle each event.
2898 Target was running and cache could be stale. This is just a
2899 heuristic. Running threads may modify target memory, but we
2900 don't get any event. */
2903 /* Go through handle_inferior_event/normal_stop, so we always
2904 have consistent output as if the stop event had been
2905 reported. */
2914 {
2919 /* Finish off the continuations. */
2923 }
2926 }
2929 }
2931 /* This function is attached as a "thread_stop_requested" observer.
2932 Cleanup local state that assumed the PTID was to be resumed, and
2933 report the stop to the frontend. */
2935 static void
2937 {
2940 /* PTID was requested to stop. Remove it from the displaced
2941 stepping queue, so we don't try to resume it automatically. */
2944 displaced;
2946 {
2952 {
2954 {
2958 }
2959 else
2960 {
2962 }
2965 }
2966 }
2969 }
2971 static void
2973 {
2976 }
2978 /* Delete the step resume, single-step and longjmp/exception resume
2979 breakpoints of TP. */
2981 static void
2983 {
2987 }
2989 /* If the target still has execution, call FUNC for each thread that
2990 just stopped. In all-stop, that's all the non-exited threads; in
2991 non-stop, that's the current thread, only. */
2996 static void
2998 {
3003 {
3004 /* If in non-stop mode, only the current thread stopped. */
3006 }
3007 else
3008 {
3011 /* In all-stop mode, all threads have stopped. */
3013 {
3015 }
3016 }
3017 }
3019 /* Delete the step resume and longjmp/exception resume breakpoints of
3020 the threads that just stopped. */
3022 static void
3024 {
3026 }
3028 /* Delete the single-step breakpoints of the threads that just
3029 stopped. */
3031 static void
3033 {
3035 }
3037 /* A cleanup wrapper. */
3039 static void
3041 {
3043 }
3045 /* Pretty print the results of target_wait, for debugging purposes. */
3047 static void
3050 {
3055 /* The text is split over several lines because it was getting too long.
3056 Call fprintf_unfiltered (gdb_stdlog) once so that the text is still
3057 output as a unit; we want only one timestamp printed if debug_timestamp
3058 is set. */
3077 status_string);
3081 /* This uses %s in part to handle %'s in the text, but also to avoid
3082 a gcc error: the format attribute requires a string literal. */
3088 }
3090 /* Prepare and stabilize the inferior for detaching it. E.g.,
3091 detaching while a thread is displaced stepping is a recipe for
3092 crashing it, as nothing would readjust the PC out of the scratch
3093 pad. */
3095 void
3097 {
3105 /* Is any thread of this process displaced stepping? If not,
3106 there's nothing else to do. */
3118 {
3127 /* Flush target cache before starting to handle each event.
3128 Target was running and cache could be stale. This is just a
3129 heuristic. Running threads may modify target memory, but we
3130 don't get any event. */
3135 else
3141 /* If an error happens while handling the event, propagate GDB's
3142 knowledge of the executing state to the frontend/user running
3143 state. */
3147 /* Now figure out what to do with the result of the result. */
3150 /* No error, don't finish the state yet. */
3153 /* Breakpoints and watchpoints are not installed on the target
3154 at this point, and signals are passed directly to the
3155 inferior, so this must mean the process is gone. */
3157 {
3160 }
3161 }
3164 }
3166 /* Wait for control to return from inferior to debugger.
3168 If inferior gets a signal, we may decide to start it up again
3169 instead of returning. That is why there is a loop in this function.
3170 When this function actually returns it means the inferior
3171 should be left stopped and GDB should read more commands. */
3173 void
3175 {
3180 fprintf_unfiltered
3183 old_cleanups
3185 NULL);
3187 /* If an error happens while handling the event, propagate GDB's
3188 knowledge of the executing state to the frontend/user running
3189 state. */
3193 {
3202 /* Flush target cache before starting to handle each event.
3203 Target was running and cache could be stale. This is just a
3204 heuristic. Running threads may modify target memory, but we
3205 don't get any event. */
3210 else
3216 /* Now figure out what to do with the result of the result. */
3221 }
3223 /* No error, don't finish the state yet. */
3227 }
3229 /* Cleanup that reinstalls the readline callback handler, if the
3230 target is running in the background. If while handling the target
3231 event something triggered a secondary prompt, like e.g., a
3232 pagination prompt, we'll have removed the callback handler (see
3233 gdb_readline_wrapper_line). Need to do this as we go back to the
3234 event loop, ready to process further input. Note this has no
3235 effect if the handler hasn't actually been removed, because calling
3236 rl_callback_handler_install resets the line buffer, thus losing
3237 input. */
3239 static void
3241 {
3243 {
3244 /* We're not going back to the top level event loop yet. Don't
3245 install the readline callback, as it'd prep the terminal,
3246 readline-style (raw, noecho) (e.g., --batch). We'll install
3247 it the next time the prompt is displayed, when we're ready
3248 for input. */
3250 }
3254 }
3256 /* Asynchronous version of wait_for_inferior. It is called by the
3257 event loop whenever a change of state is detected on the file
3258 descriptor corresponding to the target. It can be called more than
3259 once to complete a single execution command. In such cases we need
3260 to keep the state in a global variable ECSS. If it is the last time
3261 that this function is called for a single execution command, then
3262 report to the user that the inferior has stopped, and do the
3263 necessary cleanups. */
3265 void
3267 {
3278 /* End up with readline processing input, if necessary. */
3281 /* We're handling a live event, so make sure we're doing live
3282 debugging. If we're looking at traceframes while the target is
3283 running, we're going to need to get back to that mode after
3284 handling the event. */
3286 {
3289 }
3292 /* In non-stop mode, the user/frontend should not notice a thread
3293 switch due to internal events. Make sure we reverse to the
3294 user selected thread and frame after handling the event and
3295 running any breakpoint commands. */
3299 /* Flush target cache before starting to handle each event. Target
3300 was running and cache could be stale. This is just a heuristic.
3301 Running threads may modify target memory, but we don't get any
3302 event. */
3311 else
3317 /* If an error happens while handling the event, propagate GDB's
3318 knowledge of the executing state to the frontend/user running
3319 state. */
3322 else
3325 /* Get executed before make_cleanup_restore_current_thread above to apply
3326 still for the thread which has thrown the exception. */
3331 /* Now figure out what to do with the result of the result. */
3335 {
3340 /* We may not find an inferior if this was a process exit. */
3351 else
3352 {
3355 }
3356 }
3358 /* No error, don't finish the thread states yet. */
3361 /* Revert thread and frame. */
3364 /* If the inferior was in sync execution mode, and now isn't,
3365 restore the prompt (a synchronous execution command has finished,
3366 and we're ready for input). */
3371 && !was_sync
3372 && exec_done_display_p
3376 }
3378 /* Record the frame and location we're currently stepping through. */
3379 void
3381 {
3389 }
3391 /* Clear context switchable stepping state. */
3393 void
3395 {
3400 }
3402 /* Set the cached copy of the last ptid/waitstatus. */
3404 static void
3406 {
3409 }
3411 /* Return the cached copy of the last pid/waitstatus returned by
3412 target_wait()/deprecated_target_wait_hook(). The data is actually
3413 cached by handle_inferior_event(), which gets called immediately
3414 after target_wait()/deprecated_target_wait_hook(). */
3416 void
3418 {
3421 }
3423 void
3425 {
3427 }
3429 /* Switch thread contexts. */
3431 static void
3433 {
3435 {
3440 }
3443 }
3445 static void
3447 {
3453 /* If we've hit a breakpoint, we'll normally be stopped with SIGTRAP. If
3454 we aren't, just return.
3456 We assume that waitkinds other than TARGET_WAITKIND_STOPPED are not
3457 affected by gdbarch_decr_pc_after_break. Other waitkinds which are
3458 implemented by software breakpoints should be handled through the normal
3459 breakpoint layer.
3461 NOTE drow/2004-01-31: On some targets, breakpoints may generate
3462 different signals (SIGILL or SIGEMT for instance), but it is less
3463 clear where the PC is pointing afterwards. It may not match
3464 gdbarch_decr_pc_after_break. I don't know any specific target that
3465 generates these signals at breakpoints (the code has been in GDB since at
3466 least 1992) so I can not guess how to handle them here.
3468 In earlier versions of GDB, a target with
3469 gdbarch_have_nonsteppable_watchpoint would have the PC after hitting a
3470 watchpoint affected by gdbarch_decr_pc_after_break. I haven't found any
3471 target with both of these set in GDB history, and it seems unlikely to be
3472 correct, so gdbarch_have_nonsteppable_watchpoint is not checked here. */
3480 /* In reverse execution, when a breakpoint is hit, the instruction
3481 under it has already been de-executed. The reported PC always
3482 points at the breakpoint address, so adjusting it further would
3483 be wrong. E.g., consider this case on a decr_pc_after_break == 1
3484 architecture:
3486 B1 0x08000000 : INSN1
3487 B2 0x08000001 : INSN2
3488 0x08000002 : INSN3
3489 PC -> 0x08000003 : INSN4
3491 Say you're stopped at 0x08000003 as above. Reverse continuing
3492 from that point should hit B2 as below. Reading the PC when the
3493 SIGTRAP is reported should read 0x08000001 and INSN2 should have
3494 been de-executed already.
3496 B1 0x08000000 : INSN1
3497 B2 PC -> 0x08000001 : INSN2
3498 0x08000002 : INSN3
3499 0x08000003 : INSN4
3501 We can't apply the same logic as for forward execution, because
3502 we would wrongly adjust the PC to 0x08000000, since there's a
3503 breakpoint at PC - 1. We'd then report a hit on B1, although
3504 INSN1 hadn't been de-executed yet. Doing nothing is the correct
3505 behaviour. */
3509 /* If the target can tell whether the thread hit a SW breakpoint,
3510 trust it. Targets that can tell also adjust the PC
3511 themselves. */
3515 /* Note that relying on whether a breakpoint is planted in memory to
3516 determine this can fail. E.g,. the breakpoint could have been
3517 removed since. Or the thread could have been told to step an
3518 instruction the size of a breakpoint instruction, and only
3519 _after_ was a breakpoint inserted at its address. */
3521 /* If this target does not decrement the PC after breakpoints, then
3522 we have nothing to do. */
3532 /* Find the location where (if we've hit a breakpoint) the
3533 breakpoint would be. */
3536 /* If the target can't tell whether a software breakpoint triggered,
3537 fallback to figuring it out based on breakpoints we think were
3538 inserted in the target, and on whether the thread was stepped or
3539 continued. */
3541 /* Check whether there actually is a software breakpoint inserted at
3542 that location.
3544 If in non-stop mode, a race condition is possible where we've
3545 removed a breakpoint, but stop events for that breakpoint were
3546 already queued and arrive later. To suppress those spurious
3547 SIGTRAPs, we keep a list of such breakpoint locations for a bit,
3548 and retire them after a number of stop events are reported. Note
3549 this is an heuristic and can thus get confused. The real fix is
3550 to get the "stopped by SW BP and needs adjustment" info out of
3551 the target/kernel (and thus never reach here; see above). */
3554 {
3560 /* When using hardware single-step, a SIGTRAP is reported for both
3561 a completed single-step and a software breakpoint. Need to
3562 differentiate between the two, as the latter needs adjusting
3563 but the former does not.
3565 The SIGTRAP can be due to a completed hardware single-step only if
3566 - we didn't insert software single-step breakpoints
3567 - this thread is currently being stepped
3569 If any of these events did not occur, we must have stopped due
3570 to hitting a software breakpoint, and have to back up to the
3571 breakpoint address.
3573 As a special case, we could have hardware single-stepped a
3574 software breakpoint. In this case (prev_pc == breakpoint_pc),
3575 we also need to back up to the breakpoint address. */
3584 }
3585 }
3587 static int
3589 {
3593 {
3598 }
3601 }
3603 /* Auxiliary function that handles syscall entry/return events.
3604 It returns 1 if the inferior should keep going (and GDB
3605 should ignore the event), or 0 if the event deserves to be
3606 processed. */
3608 static int
3610 {
3623 {
3626 syscall_number);
3633 {
3634 /* Catchpoint hit. */
3636 }
3637 }
3639 /* If no catchpoint triggered for this, then keep going. */
3642 }
3644 /* Lazily fill in the execution_control_state's stop_func_* fields. */
3646 static void
3649 {
3651 {
3652 /* Don't care about return value; stop_func_start and stop_func_name
3653 will both be 0 if it doesn't work. */
3656 ecs->stop_func_start
3664 }
3665 }
3668 /* Return the STOP_SOON field of the inferior pointed at by PTID. */
3670 static enum stop_kind
3672 {
3677 }
3679 /* Given an execution control state that has been freshly filled in by
3680 an event from the inferior, figure out what it means and take
3681 appropriate action.
3683 The alternatives are:
3685 1) stop_waiting and return; to really stop and return to the
3686 debugger.
3688 2) keep_going and return; to wait for the next event (set
3689 ecs->event_thread->stepping_over_breakpoint to 1 to single step
3690 once). */
3692 static void
3694 {
3698 {
3699 /* We had an event in the inferior, but we are not interested in
3700 handling it at this level. The lower layers have already
3701 done what needs to be done, if anything.
3703 One of the possible circumstances for this is when the
3704 inferior produces output for the console. The inferior has
3705 not stopped, and we are ignoring the event. Another possible
3706 circumstance is any event which the lower level knows will be
3707 reported multiple times without an intervening resume. */
3712 }
3716 {
3717 /* There were no unwaited-for children left in the target, but,
3718 we're not synchronously waiting for events either. Just
3719 ignore. Otherwise, if we were running a synchronous
3720 execution command, we need to cancel it and give the user
3721 back the terminal. */
3727 }
3729 /* Cache the last pid/waitstatus. */
3732 /* Always clear state belonging to the previous time we stopped. */
3736 {
3737 /* No unwaited-for children left. IOW, all resumed children
3738 have exited. */
3745 }
3749 {
3751 /* If it's a new thread, add it to the thread database. */
3755 /* Disable range stepping. If the next step request could use a
3756 range, this will be end up re-enabled then. */
3758 }
3760 /* Dependent on valid ECS->EVENT_THREAD. */
3763 /* Dependent on the current PC value modified by adjust_pc_after_break. */
3768 /* First, distinguish signals caused by the debugger from signals
3769 that have to do with the program's own actions. Note that
3770 breakpoint insns may cause SIGTRAP or SIGILL or SIGEMT, depending
3771 on the operating system version. Here we detect when a SIGILL or
3772 SIGEMT is really a breakpoint and change it to SIGTRAP. We do
3773 something similar for SIGSEGV, since a SIGSEGV will be generated
3774 when we're trying to execute a breakpoint instruction on a
3775 non-executable stack. This happens for call dummy breakpoints
3776 for architectures like SPARC that place call dummies on the
3777 stack. */
3782 {
3787 {
3792 }
3793 }
3795 /* Mark the non-executing threads accordingly. In all-stop, all
3796 threads of all processes are stopped when we get any event
3797 reported. In non-stop mode, only the event thread stops. If
3798 we're handling a process exit in non-stop mode, there's nothing
3799 to do, as threads of the dead process are gone, and threads of
3800 any other process were left running. */
3808 {
3814 /* Ignore gracefully during startup of the inferior, as it might
3815 be the shell which has just loaded some objects, otherwise
3816 add the symbols for the newly loaded objects. Also ignore at
3817 the beginning of an attach or remote session; we will query
3818 the full list of libraries once the connection is
3819 established. */
3823 {
3835 {
3836 /* A catchpoint triggered. */
3839 }
3841 /* If requested, stop when the dynamic linker notifies
3842 gdb of events. This allows the user to get control
3843 and place breakpoints in initializer routines for
3844 dynamically loaded objects (among other things). */
3847 {
3848 /* Make sure we print "Stopped due to solib-event" in
3849 normal_stop. */
3854 }
3855 }
3857 /* If we are skipping through a shell, or through shared library
3858 loading that we aren't interested in, resume the program. If
3859 we're running the program normally, also resume. */
3861 {
3862 /* Loading of shared libraries might have changed breakpoint
3863 addresses. Make sure new breakpoints are inserted. */
3869 }
3871 /* But stop if we're attaching or setting up a remote
3872 connection. */
3875 {
3880 }
3897 {
3901 else
3904 }
3912 /* Clearing any previous state of convenience variables. */
3916 {
3917 /* Record the exit code in the convenience variable $_exitcode, so
3918 that the user can inspect this again later. */
3922 /* Also record this in the inferior itself. */
3926 /* Support the --return-child-result option. */
3930 }
3931 else
3932 {
3937 {
3938 /* Set the value of the internal variable $_exitsignal,
3939 which holds the signal uncaught by the inferior. */
3943 }
3944 else
3945 {
3946 /* We don't have access to the target's method used for
3947 converting between signal numbers (GDB's internal
3948 representation <-> target's representation).
3949 Therefore, we cannot do a good job at displaying this
3950 information to the user. It's better to just warn
3951 her about it (if infrun debugging is enabled), and
3952 give up. */
3956 }
3959 }
3967 /* The following are the only cases in which we keep going;
3968 the above cases end in a continue or goto. */
3972 {
3975 else
3977 }
3979 /* Check whether the inferior is displaced stepping. */
3980 {
3986 /* If checking displaced stepping is supported, and thread
3987 ecs->ptid is displaced stepping. */
3989 {
3993 CORE_ADDR parent_pc;
3995 /* GDB has got TARGET_WAITKIND_FORKED or TARGET_WAITKIND_VFORKED,
3996 indicating that the displaced stepping of syscall instruction
3997 has been done. Perform cleanup for parent process here. Note
3998 that this operation also cleans up the child process for vfork,
3999 because their pages are shared. */
4003 {
4004 /* Restore scratch pad for child process. */
4006 }
4008 /* Since the vfork/fork syscall instruction was executed in the scratchpad,
4009 the child's PC is also within the scratchpad. Set the child's PC
4010 to the parent's PC value, which has already been fixed up.
4011 FIXME: we use the parent's aspace here, although we're touching
4012 the child, because the child hasn't been added to the inferior
4013 list yet at this point. */
4015 child_regcache
4017 gdbarch,
4019 /* Read PC value of parent process. */
4030 }
4031 }
4036 /* Immediately detach breakpoints from the child before there's
4037 any chance of letting the user delete breakpoints from the
4038 breakpoint lists. If we don't do this early, it's easy to
4039 leave left over traps in the child, vis: "break foo; catch
4040 fork; c; <fork>; del; c; <child calls foo>". We only follow
4041 the fork on the last `continue', and by that time the
4042 breakpoint at "foo" is long gone from the breakpoint table.
4043 If we vforked, then we don't need to unpatch here, since both
4044 parent and child are sharing the same memory pages; we'll
4045 need to unpatch at follow/detach time instead to be certain
4046 that new breakpoints added between catchpoint hit time and
4047 vfork follow are detached. */
4049 {
4050 /* This won't actually modify the breakpoint list, but will
4051 physically remove the breakpoints from the child. */
4053 }
4057 /* In case the event is caught by a catchpoint, remember that
4058 the event is to be followed at the next resume of the thread,
4059 and not immediately. */
4068 /* If no catchpoint triggered for this, then keep going. Note
4069 that we're interested in knowing the bpstat actually causes a
4070 stop, not just if it may explain the signal. Software
4071 watchpoints, for example, always appear in the bpstat. */
4073 {
4074 ptid_t parent;
4075 ptid_t child;
4077 int follow_child
4087 /* In non-stop mode, also resume the other branch. */
4089 {
4092 else
4098 }
4102 else
4110 else
4113 }
4118 /* Done with the shared memory region. Re-insert breakpoints in
4119 the parent, and keep going. */
4130 /* This also takes care of reinserting breakpoints in the
4131 previously locked inferior. */
4144 /* Do whatever is necessary to the parent branch of the vfork. */
4147 /* This causes the eventpoints and symbol table to be reset.
4148 Must do this now, before trying to determine whether to
4149 stop. */
4156 /* Note that this may be referenced from inside
4157 bpstat_stop_status above, through inferior_has_execd. */
4161 /* If no catchpoint triggered for this, then keep going. */
4163 {
4167 }
4171 /* Be careful not to try to gather much state about a thread
4172 that's in a syscall. It's frequently a losing proposition. */
4177 /* Getting the current syscall number. */
4182 /* Before examining the threads further, step this thread to
4183 get it entirely out of the syscall. (We get notice of the
4184 event when the thread is just on the verge of exiting a
4185 syscall. Stepping one instruction seems to get it back
4186 into user code.) */
4205 /* Reverse execution: target ran out of history info. */
4212 }
4213 }
4215 /* Come here when the program has stopped with a signal. */
4217 static void
4219 {
4228 /* Do we need to clean up the state of a thread that has
4229 completed a displaced single-step? (Doing so usually affects
4230 the PC, so do it here, before we set stop_pc.) */
4234 /* If we either finished a single-step or hit a breakpoint, but
4235 the user wanted this thread to be stopped, pretend we got a
4236 SIG0 (generic unsignaled stop). */
4244 {
4254 {
4255 CORE_ADDR addr;
4263 else
4266 }
4269 }
4271 /* This is originated from start_remote(), start_inferior() and
4272 shared libraries hook functions. */
4275 {
4283 }
4287 {
4295 }
4297 /* This originates from attach_command(). We need to overwrite
4298 the stop_signal here, because some kernels don't ignore a
4299 SIGSTOP in a subsequent ptrace(PTRACE_CONT,SIGSTOP) call.
4300 See more comments in inferior.h. On the other hand, if we
4301 get a non-SIGSTOP, report it to the user - assume the backend
4302 will handle the SIGSTOP if it should show up later.
4304 Also consider that the attach is complete when we see a
4305 SIGTRAP. Some systems (e.g. Windows), and stubs supporting
4306 target extended-remote report it instead of a SIGSTOP
4307 (e.g. gdbserver). We already rely on SIGTRAP being our
4308 signal, so this is no exception.
4310 Also consider that the attach is complete when we see a
4311 GDB_SIGNAL_0. In non-stop mode, GDB will explicitly tell
4312 the target to stop all threads of the inferior, in case the
4313 low level attach operation doesn't stop them implicitly. If
4314 they weren't stopped implicitly, then the stub will report a
4315 GDB_SIGNAL_0, meaning: stopped for no particular reason
4316 other than GDB's request. */
4321 {
4326 }
4328 /* See if something interesting happened to the non-current thread. If
4329 so, then switch to that thread. */
4331 {
4339 }
4341 /* At this point, get hold of the now-current thread's frame. */
4345 /* Pull the single step breakpoints out of the target. */
4347 {
4350 CORE_ADDR pc;
4356 /* However, before doing so, if this single-step breakpoint was
4357 actually for another thread, set this thread up for moving
4358 past it. */
4361 {
4363 {
4365 {
4367 "infrun: [%s] hit another thread's "
4370 }
4372 }
4373 }
4374 else
4375 {
4377 {
4379 "infrun: [%s] hit its "
4382 }
4383 }
4384 }
4391 else
4394 /* If necessary, step over this watchpoint. We'll be back to display
4395 it in a moment. */
4397 && (target_have_steppable_watchpoint
4399 {
4400 /* At this point, we are stopped at an instruction which has
4401 attempted to write to a piece of memory under control of
4402 a watchpoint. The instruction hasn't actually executed
4403 yet. If we were to evaluate the watchpoint expression
4404 now, we would get the old value, and therefore no change
4405 would seem to have occurred.
4407 In order to make watchpoints work `right', we really need
4408 to complete the memory write, and then evaluate the
4409 watchpoint expression. We do this by single-stepping the
4410 target.
4412 It may not be necessary to disable the watchpoint to step over
4413 it. For example, the PA can (with some kernel cooperation)
4414 single step over a watchpoint without disabling the watchpoint.
4416 It is far more common to need to disable a watchpoint to step
4417 the inferior over it. If we have non-steppable watchpoints,
4418 we must disable the current watchpoint; it's simplest to
4419 disable all watchpoints.
4421 Any breakpoint at PC must also be stepped over -- if there's
4422 one, it will have already triggered before the watchpoint
4423 triggered, and we either already reported it to the user, or
4424 it didn't cause a stop and we called keep_going. In either
4425 case, if there was a breakpoint at PC, we must be trying to
4426 step past it. */
4430 }
4439 /* Hide inlined functions starting here, unless we just performed stepi or
4440 nexti. After stepi and nexti, always show the innermost frame (not any
4441 inline function call sites). */
4443 {
4447 /* skip_inline_frames is expensive, so we avoid it if we can
4448 determine that the address is one where functions cannot have
4449 been inlined. This improves performance with inferiors that
4450 load a lot of shared libraries, because the solib event
4451 breakpoint is defined as the address of a function (i.e. not
4452 inline). Note that we have to check the previous PC as well
4453 as the current one to catch cases when we have just
4454 single-stepped off a breakpoint prior to reinstating it.
4455 Note that we're assuming that the code we single-step to is
4456 not inline, but that's not definitive: there's nothing
4457 preventing the event breakpoint function from containing
4458 inlined code, and the single-step ending up there. If the
4459 user had set a breakpoint on that inlined code, the missing
4460 skip_inline_frames call would break things. Fortunately
4461 that's an extremely unlikely scenario. */
4468 {
4471 /* Re-fetch current thread's frame in case that invalidated
4472 the frame cache. */
4475 }
4476 }
4482 {
4483 /* We're trying to step off a breakpoint. Turns out that we're
4484 also on an instruction that needs to be stepped multiple
4485 times before it's been fully executing. E.g., architectures
4486 with a delay slot. It needs to be stepped twice, once for
4487 the instruction and once for the delay slot. */
4488 int step_through_delay
4495 {
4496 /* The user issued a continue when stopped at a breakpoint.
4497 Set up for another trap and get out of here. */
4501 }
4503 {
4504 /* The user issued a step when stopped at a breakpoint.
4505 Maybe we should stop, maybe we should not - the delay
4506 slot *might* correspond to a line of source. In any
4507 case, don't decide that here, just set
4508 ecs->stepping_over_breakpoint, making sure we
4509 single-step again before breakpoints are re-inserted. */
4511 }
4512 }
4514 /* See if there is a breakpoint/watchpoint/catchpoint/etc. that
4515 handles this event. */
4520 /* Following in case break condition called a
4521 function. */
4524 /* This is where we handle "moribund" watchpoints. Unlike
4525 software breakpoints traps, hardware watchpoint traps are
4526 always distinguishable from random traps. If no high-level
4527 watchpoint is associated with the reported stop data address
4528 anymore, then the bpstat does not explain the signal ---
4529 simply make sure to ignore it if `stopped_by_watchpoint' is
4530 set. */
4535 GDB_SIGNAL_TRAP)
4538 "infrun: no user watchpoint explains "
4541 /* NOTE: cagney/2003-03-29: These checks for a random signal
4542 at one stage in the past included checks for an inferior
4543 function call's call dummy's return breakpoint. The original
4544 comment, that went with the test, read:
4546 ``End of a stack dummy. Some systems (e.g. Sony news) give
4547 another signal besides SIGTRAP, so check here as well as
4548 above.''
4550 If someone ever tries to get call dummys on a
4551 non-executable stack to work (where the target would stop
4552 with something like a SIGSEGV), then those tests might need
4553 to be re-instated. Given, however, that the tests were only
4554 enabled when momentary breakpoints were not being used, I
4555 suspect that it won't be the case.
4557 NOTE: kettenis/2004-02-05: Indeed such checks don't seem to
4558 be necessary for call dummies on a non-executable stack on
4559 SPARC. */
4561 /* See if the breakpoints module can explain the signal. */
4562 random_signal
4566 /* Maybe this was a trap for a software breakpoint that has since
4567 been removed. */
4569 {
4571 {
4575 /* Re-adjust PC to what the program would see if GDB was not
4576 debugging it. */
4580 {
4589 }
4590 }
4591 else
4592 {
4593 /* A delayed software breakpoint event. Ignore the trap. */
4596 "infrun: delayed software breakpoint "
4599 }
4600 }
4602 /* Maybe this was a trap for a hardware breakpoint/watchpoint that
4603 has since been removed. */
4605 {
4606 /* A delayed hardware breakpoint event. Ignore the trap. */
4609 "infrun: delayed hardware breakpoint/watchpoint "
4612 }
4614 /* If not, perhaps stepping/nexting can. */
4619 /* Perhaps the thread hit a single-step breakpoint of _another_
4620 thread. Single-step breakpoints are transparent to the
4621 breakpoints module. */
4625 /* No? Perhaps we got a moribund watchpoint. */
4629 /* For the program's own signals, act according to
4630 the signal handling tables. */
4633 {
4634 /* Signal not for debugging purposes. */
4644 /* Always stop on signals if we're either just gaining control
4645 of the program, or the user explicitly requested this thread
4646 to remain stopped. */
4651 {
4654 }
4656 /* Notify observers the signal has "handle print" set. Note we
4657 returned early above if stopping; normal_stop handles the
4658 printing in that case. */
4660 {
4661 /* The signal table tells us to print about this signal. */
4665 }
4667 /* Clear the signal if it should not be passed. */
4674 {
4675 /* We were just starting a new sequence, attempting to
4676 single-step off of a breakpoint and expecting a SIGTRAP.
4677 Instead this signal arrives. This signal will take us out
4678 of the stepping range so GDB needs to remember to, when
4679 the signal handler returns, resume stepping off that
4680 breakpoint. */
4681 /* To simplify things, "continue" is forced to use the same
4682 code paths as single-step - set a breakpoint at the
4683 signal return address and then, once hit, step off that
4684 breakpoint. */
4687 "infrun: signal arrived while stepping over "
4692 /* Reset trap_expected to ensure breakpoints are re-inserted. */
4695 /* If we were nexting/stepping some other thread, switch to
4696 it, so that we don't continue it, losing control. */
4700 }
4708 {
4709 /* The inferior is about to take a signal that will take it
4710 out of the single step range. Set a breakpoint at the
4711 current PC (which is presumably where the signal handler
4712 will eventually return) and then allow the inferior to
4713 run free.
4715 Note that this is only needed for a signal delivered
4716 while in the single-step range. Nested signals aren't a
4717 problem as they eventually all return. */
4720 "infrun: signal may take us out of "
4725 /* Reset trap_expected to ensure breakpoints are re-inserted. */
4729 }
4731 /* Note: step_resume_breakpoint may be non-NULL. This occures
4732 when either there's a nested signal, or when there's a
4733 pending signal enabled just as the signal handler returns
4734 (leaving the inferior at the step-resume-breakpoint without
4735 actually executing it). Either way continue until the
4736 breakpoint is really hit. */
4739 {
4745 }
4747 }
4750 }
4752 /* Come here when we've got some debug event / signal we can explain
4753 (IOW, not a random signal), and test whether it should cause a
4754 stop, or whether we should resume the inferior (transparently).
4755 E.g., could be a breakpoint whose condition evaluates false; we
4756 could be still stepping within the line; etc. */
4758 static void
4760 {
4764 CORE_ADDR jmp_buf_pc;
4767 /* Handle cases caused by hitting a breakpoint. */
4775 {
4777 }
4779 /* If we hit an internal event that triggers symbol changes, the
4780 current frame will be invalidated within bpstat_what (e.g., if we
4781 hit an internal solib event). Re-fetch it. */
4786 {
4788 /* If we hit the breakpoint at longjmp while stepping, we
4789 install a momentary breakpoint at the target of the
4790 jmp_buf. */
4799 {
4802 /* If we set the longjmp breakpoint via a SystemTap probe,
4803 then use it to extract the arguments. The destination PC
4804 is the third argument to the probe. */
4807 {
4810 }
4814 {
4817 "infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME "
4821 }
4823 /* Insert a breakpoint at resume address. */
4825 }
4826 else
4832 {
4835 /* There are several cases to consider.
4837 1. The initiating frame no longer exists. In this case we
4838 must stop, because the exception or longjmp has gone too
4839 far.
4841 2. The initiating frame exists, and is the same as the
4842 current frame. We stop, because the exception or longjmp
4843 has been caught.
4845 3. The initiating frame exists and is different from the
4846 current frame. This means the exception or longjmp has
4847 been caught beneath the initiating frame, so keep going.
4849 4. longjmp breakpoint has been placed just to protect
4850 against stale dummy frames and user is not interested in
4851 stopping around longjmps. */
4862 {
4866 {
4867 /* Case 4. */
4870 }
4871 }
4876 {
4877 struct frame_id current_id
4881 {
4882 /* Case 2. Fall through. */
4883 }
4884 else
4885 {
4886 /* Case 3. */
4889 }
4890 }
4892 /* For Cases 1 and 2, remove the step-resume breakpoint, if it
4893 exists. */
4897 }
4904 /* Still need to check other stuff, at least the case where we
4905 are stepping and step out of the right range. */
4915 {
4918 /* We are finishing a function in reverse, and just hit the
4919 step-resume breakpoint at the start address of the
4920 function, and we're almost there -- just need to back up
4921 by one more single-step, which should take us back to the
4922 function call. */
4926 }
4930 {
4931 /* We are stepping over a function call in reverse, and just
4932 hit the step-resume breakpoint at the start address of
4933 the function. Go back to single-stepping, which should
4934 take us back to the function call. */
4938 }
4946 /* Assume the thread stopped for a breapoint. We'll still check
4947 whether a/the breakpoint is there when the thread is next
4948 resumed. */
4959 /* Assume the thread stopped for a breapoint. We'll still check
4960 whether a/the breakpoint is there when the thread is next
4961 resumed. */
4972 {
4973 /* Back when the step-resume breakpoint was inserted, we
4974 were trying to single-step off a breakpoint. Go back to
4975 doing that. */
4980 }
4985 }
4987 /* If we stepped a permanent breakpoint and we had a high priority
4988 step-resume breakpoint for the address we stepped, but we didn't
4989 hit it, then we must have stepped into the signal handler. The
4990 step-resume was only necessary to catch the case of _not_
4991 stepping into the handler, so delete it, and fall through to
4992 checking whether the step finished. */
4994 {
5002 {
5005 "infrun: stepped permanent breakpoint, stopped in "
5009 }
5010 }
5012 /* We come here if we hit a breakpoint but should not stop for it.
5013 Possibly we also were stepping and should stop for that. So fall
5014 through and test for stepping. But, if not stepping, do not
5015 stop. */
5017 /* In all-stop mode, if we're currently stepping but have stopped in
5018 some other thread, we need to switch back to the stepped thread. */
5023 {
5028 /* Having a step-resume breakpoint overrides anything
5029 else having to do with stepping commands until
5030 that breakpoint is reached. */
5033 }
5036 {
5039 /* Likewise if we aren't even stepping. */
5042 }
5044 /* Re-fetch current thread's frame in case the code above caused
5045 the frame cache to be re-initialized, making our FRAME variable
5046 a dangling pointer. */
5051 /* If stepping through a line, keep going if still within it.
5053 Note that step_range_end is the address of the first instruction
5054 beyond the step range, and NOT the address of the last instruction
5055 within it!
5057 Note also that during reverse execution, we may be stepping
5058 through a function epilogue and therefore must detect when
5059 the current-frame changes in the middle of a line. */
5065 {
5067 fprintf_unfiltered
5072 /* Tentatively re-enable range stepping; `resume' disables it if
5073 necessary (e.g., if we're stepping over a breakpoint or we
5074 have software watchpoints). */
5077 /* When stepping backward, stop at beginning of line range
5078 (unless it's the function entry point, in which case
5079 keep going back to the call point). */
5084 else
5088 }
5090 /* We stepped out of the stepping range. */
5092 /* If we are stepping at the source level and entered the runtime
5093 loader dynamic symbol resolution code...
5095 EXEC_FORWARD: we keep on single stepping until we exit the run
5096 time loader code and reach the callee's address.
5098 EXEC_REVERSE: we've already executed the callee (backward), and
5099 the runtime loader code is handled just like any other
5100 undebuggable function call. Now we need only keep stepping
5101 backward through the trampoline code, and that's handled further
5102 down, so there is nothing for us to do here. */
5107 {
5108 CORE_ADDR pc_after_resolver =
5116 {
5117 /* Set up a step-resume breakpoint at the address
5118 indicated by SKIP_SOLIB_RESOLVER. */
5127 }
5131 }
5137 {
5141 /* The inferior, while doing a "step" or "next", has ended up in
5142 a signal trampoline (either by a signal being delivered or by
5143 the signal handler returning). Just single-step until the
5144 inferior leaves the trampoline (either by calling the handler
5145 or returning). */
5148 }
5150 /* If we're in the return path from a shared library trampoline,
5151 we want to proceed through the trampoline when stepping. */
5152 /* macro/2012-04-25: This needs to come before the subroutine
5153 call check below as on some targets return trampolines look
5154 like subroutine calls (MIPS16 return thunks). */
5158 {
5159 /* Determine where this trampoline returns. */
5160 CORE_ADDR real_stop_pc;
5168 /* Only proceed through if we know where it's going. */
5170 {
5171 /* And put the step-breakpoint there and go until there. */
5179 /* Do not specify what the fp should be when we stop since
5180 on some machines the prologue is where the new fp value
5181 is established. */
5185 /* Restart without fiddling with the step ranges or
5186 other state. */
5189 }
5190 }
5192 /* Check for subroutine calls. The check for the current frame
5193 equalling the step ID is not necessary - the check of the
5194 previous frame's ID is sufficient - but it is a common case and
5195 cheaper than checking the previous frame's ID.
5197 NOTE: frame_id_eq will never report two invalid frame IDs as
5198 being equal, so to get into this block, both the current and
5199 previous frame must have valid frame IDs. */
5200 /* The outer_frame_id check is a heuristic to detect stepping
5201 through startup code. If we step over an instruction which
5202 sets the stack pointer from an invalid value to a valid value,
5203 we may detect that as a subroutine call from the mythical
5204 "outermost" function. This could be fixed by marking
5205 outermost frames as !stack_p,code_p,special_p. Then the
5206 initial outermost frame, before sp was valid, would
5207 have code_addr == &_start. See the comment in frame_id_eq
5208 for more. */
5214 outer_frame_id)
5217 {
5218 CORE_ADDR real_stop_pc;
5224 {
5225 /* I presume that step_over_calls is only 0 when we're
5226 supposed to be stepping at the assembly language level
5227 ("stepi"). Just stop. */
5228 /* And this works the same backward as frontward. MVS */
5231 }
5233 /* Reverse stepping through solib trampolines. */
5240 {
5241 /* Any solib trampoline code can be handled in reverse
5242 by simply continuing to single-step. We have already
5243 executed the solib function (backwards), and a few
5244 steps will take us back through the trampoline to the
5245 caller. */
5248 }
5251 {
5252 /* We're doing a "next".
5254 Normal (forward) execution: set a breakpoint at the
5255 callee's return address (the address at which the caller
5256 will resume).
5258 Reverse (backward) execution. set the step-resume
5259 breakpoint at the start of the function that we just
5260 stepped into (backwards), and continue to there. When we
5261 get there, we'll need to single-step back to the caller. */
5264 {
5265 /* If we're already at the start of the function, we've either
5266 just stepped backward into a single instruction function,
5267 or stepped back out of a signal handler to the first instruction
5268 of the function. Just keep going, which will single-step back
5269 to the caller. */
5271 {
5274 /* Normal function call return (static or dynamic). */
5280 }
5281 }
5282 else
5287 }
5289 /* If we are in a function call trampoline (a stub between the
5290 calling routine and the real function), locate the real
5291 function. That's what tells us (a) whether we want to step
5292 into it at all, and (b) what prologue we want to run to the
5293 end of, if we do step into it. */
5301 {
5312 }
5314 /* If we have line number information for the function we are
5315 thinking of stepping into and the function isn't on the skip
5316 list, step into it.
5318 If there are several symtabs at that PC (e.g. with include
5319 files), just want to know whether *any* of them have line
5320 numbers. find_pc_line handles this. */
5321 {
5328 {
5331 else
5334 }
5335 }
5337 /* If we have no line number and the step-stop-if-no-debug is
5338 set, we stop the step so that the user has a chance to switch
5339 in assembly mode. */
5342 {
5345 }
5348 {
5349 /* If we're already at the start of the function, we've either just
5350 stepped backward into a single instruction function without line
5351 number info, or stepped back out of a signal handler to the first
5352 instruction of the function without line number info. Just keep
5353 going, which will single-step back to the caller. */
5355 {
5356 /* Set a breakpoint at callee's start address.
5357 From there we can step once and be back in the caller. */
5365 }
5366 }
5367 else
5368 /* Set a breakpoint at callee's return address (the address
5369 at which the caller will resume). */
5374 }
5376 /* Reverse stepping through solib trampolines. */
5380 {
5384 {
5385 /* Any solib trampoline code can be handled in reverse
5386 by simply continuing to single-step. We have already
5387 executed the solib function (backwards), and a few
5388 steps will take us back through the trampoline to the
5389 caller. */
5392 }
5394 {
5395 /* Stepped backward into the solib dynsym resolver.
5396 Set a breakpoint at its start and continue, then
5397 one more step will take us out. */
5407 }
5408 }
5412 /* NOTE: tausq/2004-05-24: This if block used to be done before all
5413 the trampoline processing logic, however, there are some trampolines
5414 that have no names, so we should do trampoline handling first. */
5418 {
5423 /* The inferior just stepped into, or returned to, an
5424 undebuggable function (where there is no debugging information
5425 and no line number corresponding to the address where the
5426 inferior stopped). Since we want to skip this kind of code,
5427 we keep going until the inferior returns from this
5428 function - unless the user has asked us not to (via
5429 set step-mode) or we no longer know how to get back
5430 to the call site. */
5433 {
5434 /* If we have no line number and the step-stop-if-no-debug
5435 is set, we stop the step so that the user has a chance to
5436 switch in assembly mode. */
5439 }
5440 else
5441 {
5442 /* Set a breakpoint at callee's return address (the address
5443 at which the caller will resume). */
5447 }
5448 }
5451 {
5452 /* It is stepi or nexti. We always want to stop stepping after
5453 one instruction. */
5458 }
5461 {
5462 /* We have no line number information. That means to stop
5463 stepping (does this always happen right after one instruction,
5464 when we do "s" in a function with no line numbers,
5465 or can this happen as a result of a return or longjmp?). */
5470 }
5472 /* Look for "calls" to inlined functions, part one. If the inline
5473 frame machinery detected some skipped call sites, we have entered
5474 a new inline function. */
5479 {
5489 {
5490 /* For "step", we're going to stop. But if the call site
5491 for this inlined function is on the same source line as
5492 we were previously stepping, go down into the function
5493 first. Otherwise stop at the call site. */
5501 }
5502 else
5503 {
5504 /* For "next", we should stop at the call site if it is on a
5505 different source line. Otherwise continue through the
5506 inlined function. */
5510 else
5513 }
5514 }
5516 /* Look for "calls" to inlined functions, part two. If we are still
5517 in the same real function we were stepping through, but we have
5518 to go further up to find the exact frame ID, we are stepping
5519 through a more inlined call beyond its call site. */
5526 {
5533 else
5536 }
5541 {
5542 /* We are at the start of a different line. So stop. Note that
5543 we don't stop if we step into the middle of a different line.
5544 That is said to make things like for (;;) statements work
5545 better. */
5551 }
5553 /* We aren't done stepping.
5555 Optimize by setting the stepping range to the line.
5556 (We might not be in the original line, but if we entered a
5557 new line in mid-statement, we continue stepping. This makes
5558 things like for(;;) statements work better.) */
5568 }
5570 /* In all-stop mode, if we're currently stepping but have stopped in
5571 some other thread, we may need to switch back to the stepped
5572 thread. Returns true we set the inferior running, false if we left
5573 it stopped (and the event needs further processing). */
5575 static int
5577 {
5579 {
5584 /* If any thread is blocked on some internal breakpoint, and we
5585 simply need to step over that breakpoint to get it going
5586 again, do that first. */
5588 /* However, if we see an event for the stepping thread, then we
5589 know all other threads have been moved past their breakpoints
5590 already. Let the caller check whether the step is finished,
5591 etc., before deciding to move it past a breakpoint. */
5595 /* Check if the current thread is blocked on an incomplete
5596 step-over, interrupted by a random signal. */
5599 {
5601 {
5605 }
5608 }
5610 /* Check if the current thread is blocked by a single-step
5611 breakpoint of another thread. */
5613 {
5615 {
5617 "infrun: need to step [%s] over single-step "
5620 }
5623 }
5625 /* Otherwise, we no longer expect a trap in the current thread.
5626 Clear the trap_expected flag before switching back -- this is
5627 what keep_going does as well, if we call it. */
5630 /* Likewise, clear the signal if it should not be passed. */
5634 /* If scheduler locking applies even if not stepping, there's no
5635 need to walk over threads. Above we've checked whether the
5636 current thread is stepping. If some other thread not the
5637 event thread is stepping, then it must be that scheduler
5638 locking is not in effect. */
5642 /* Look for the stepping/nexting thread, and check if any other
5643 thread other than the stepping thread needs to start a
5644 step-over. Do all step-overs before actually proceeding with
5645 step/next/etc. */
5649 {
5650 /* Ignore threads of processes we're not resuming. */
5655 /* When stepping over a breakpoint, we lock all threads
5656 except the one that needs to move past the breakpoint.
5657 If a non-event thread has this set, the "incomplete
5658 step-over" check above should have caught it earlier. */
5661 /* Did we find the stepping thread? */
5663 {
5664 /* Yep. There should only one though. */
5667 /* The event thread is handled at the top, before we
5668 enter this loop. */
5671 /* If some thread other than the event thread is
5672 stepping, then scheduler locking can't be in effect,
5673 otherwise we wouldn't have resumed the current event
5674 thread in the first place. */
5678 }
5680 {
5683 /* At the top we've returned early if the event thread
5684 is stepping. If some other thread not the event
5685 thread is stepping, then scheduler locking can't be
5686 in effect, and we can resume this thread. No need to
5687 keep looking for the stepping thread then. */
5689 }
5690 }
5693 {
5696 {
5700 }
5702 /* Only the stepping thread should have this set. */
5710 }
5713 {
5719 /* If the stepping thread exited, then don't try to switch
5720 back and resume it, which could fail in several different
5721 ways depending on the target. Instead, just keep going.
5723 We can find a stepping dead thread in the thread list in
5724 two cases:
5726 - The target supports thread exit events, and when the
5727 target tries to delete the thread from the thread list,
5728 inferior_ptid pointed at the exiting thread. In such
5729 case, calling delete_thread does not really remove the
5730 thread from the list; instead, the thread is left listed,
5731 with 'exited' state.
5733 - The target's debug interface does not support thread
5734 exit events, and so we have no idea whatsoever if the
5735 previously stepping thread is still alive. For that
5736 reason, we need to synchronously query the target
5737 now. */
5740 {
5743 "infrun: not switching back to "
5749 }
5763 /* If the PC of the thread we were trying to single-step has
5764 changed, then that thread has trapped or been signaled,
5765 but the event has not been reported to GDB yet. Re-poll
5766 the target looking for this particular thread's event
5767 (i.e. temporarily enable schedlock) by:
5769 - setting a break at the current PC
5770 - resuming that particular thread, only (by setting
5771 trap expected)
5773 This prevents us continuously moving the single-step
5774 breakpoint forward, one instruction at a time,
5775 overstepping. */
5778 {
5779 ptid_t resume_ptid;
5785 /* Clear the info of the previous step-over, as it's no
5786 longer valid. It's what keep_going would do too, if
5787 we called it. Must do this before trying to insert
5788 the sss breakpoint, otherwise if we were previously
5789 trying to step over this exact address in another
5790 thread, the breakpoint ends up not installed. */
5795 stop_pc);
5801 }
5802 else
5803 {
5806 "infrun: expected thread still "
5809 }
5812 }
5813 }
5815 }
5817 /* Is thread TP in the middle of single-stepping? */
5819 static int
5821 {
5827 }
5829 /* Inferior has stepped into a subroutine call with source code that
5830 we should not step over. Do step to the first line of code in
5831 it. */
5833 static void
5836 {
5848 /* Use the step_resume_break to step until the end of the prologue,
5849 even if that involves jumps (as it seems to on the vax under
5850 4.2). */
5851 /* If the prologue ends in the middle of a source line, continue to
5852 the end of that source line (if it is still within the function).
5853 Otherwise, just go to end of prologue. */
5859 /* Architectures which require breakpoint adjustment might not be able
5860 to place a breakpoint at the computed address. If so, the test
5861 ``ecs->stop_func_start == stop_pc'' will never succeed. Adjust
5862 ecs->stop_func_start to an address at which a breakpoint may be
5863 legitimately placed.
5865 Note: kevinb/2004-01-19: On FR-V, if this adjustment is not
5866 made, GDB will enter an infinite loop when stepping through
5867 optimized code consisting of VLIW instructions which contain
5868 subinstructions corresponding to different source lines. On
5869 FR-V, it's not permitted to place a breakpoint on any but the
5870 first subinstruction of a VLIW instruction. When a breakpoint is
5871 set, GDB will adjust the breakpoint address to the beginning of
5872 the VLIW instruction. Thus, we need to make the corresponding
5873 adjustment here when computing the stop address. */
5876 {
5877 ecs->stop_func_start
5880 }
5883 {
5884 /* We are already there: stop now. */
5887 }
5888 else
5889 {
5890 /* Put the step-breakpoint there and go until there. */
5896 /* Do not specify what the fp should be when we stop since on
5897 some machines the prologue is where the new fp value is
5898 established. */
5901 /* And make sure stepping stops right away then. */
5904 }
5906 }
5908 /* Inferior has stepped backward into a subroutine call with source
5909 code that we should not step over. Do step to the beginning of the
5910 last line of code in it. */
5912 static void
5915 {
5928 /* OK, we're just going to keep stepping here. */
5930 {
5931 /* We're there already. Just stop stepping now. */
5933 }
5934 else
5935 {
5936 /* Else just reset the step range and keep going.
5937 No step-resume breakpoint, they don't work for
5938 epilogues, which can have multiple entry paths. */
5942 }
5944 }
5946 /* Insert a "step-resume breakpoint" at SR_SAL with frame ID SR_ID.
5947 This is used to both functions and to skip over code. */
5949 static void
5954 {
5955 /* There should never be more than one step-resume or longjmp-resume
5956 breakpoint per thread, so we should never be setting a new
5957 step_resume_breakpoint when one is already active. */
5968 }
5970 void
5974 {
5977 bp_step_resume);
5978 }
5980 /* Insert a "high-priority step-resume breakpoint" at RETURN_FRAME.pc.
5981 This is used to skip a potential signal handler.
5983 This is called with the interrupted function's frame. The signal
5984 handler, when it returns, will resume the interrupted function at
5985 RETURN_FRAME.pc. */
5987 static void
5989 {
6003 bp_hp_step_resume);
6004 }
6006 /* Insert a "step-resume breakpoint" at the previous frame's PC. This
6007 is used to skip a function after stepping into it (for "next" or if
6008 the called function has no debugging information).
6010 The current function has almost always been reached by single
6011 stepping a call or return instruction. NEXT_FRAME belongs to the
6012 current function, and the breakpoint will be set at the caller's
6013 resume address.
6015 This is a separate function rather than reusing
6016 insert_hp_step_resume_breakpoint_at_frame in order to avoid
6017 get_prev_frame, which may stop prematurely (see the implementation
6018 of frame_unwind_caller_id for an example). */
6020 static void
6022 {
6026 /* We shouldn't have gotten here if we don't know where the call site
6027 is. */
6040 }
6042 /* Insert a "longjmp-resume" breakpoint at PC. This is used to set a
6043 new breakpoint at the target of a jmp_buf. The handling of
6044 longjmp-resume uses the same mechanisms used for handling
6045 "step-resume" breakpoints. */
6047 static void
6049 {
6050 /* There should never be more than one longjmp-resume breakpoint per
6051 thread, so we should never be setting a new
6052 longjmp_resume_breakpoint when one is already active. */
6062 }
6064 /* Insert an exception resume breakpoint. TP is the thread throwing
6065 the exception. The block B is the block of the unwinder debug hook
6066 function. FRAME is the frame corresponding to the call to this
6067 function. SYM is the symbol of the function argument holding the
6068 target PC of the exception. */
6070 static void
6075 {
6076 TRY
6077 {
6080 CORE_ADDR handler;
6085 /* If the value was optimized out, revert to the old behavior. */
6087 {
6098 /* set_momentary_breakpoint_at_pc invalidates FRAME. */
6103 }
6104 }
6106 {
6107 /* We want to ignore errors here. */
6108 }
6109 END_CATCH
6110 }
6112 /* A helper for check_exception_resume that sets an
6113 exception-breakpoint based on a SystemTap probe. */
6115 static void
6119 {
6121 CORE_ADDR handler;
6134 handler));
6140 }
6142 /* This is called when an exception has been intercepted. Check to
6143 see whether the exception's destination is of interest, and if so,
6144 set an exception resume breakpoint there. */
6146 static void
6149 {
6153 /* First see if this exception unwinding breakpoint was set via a
6154 SystemTap probe point. If so, the probe has two arguments: the
6155 CFA and the HANDLER. We ignore the CFA, extract the handler, and
6156 set a breakpoint there. */
6159 {
6162 }
6168 TRY
6169 {
6175 /* The exception breakpoint is a thread-specific breakpoint on
6176 the unwinder's debug hook, declared as:
6178 void _Unwind_DebugHook (void *cfa, void *handler);
6180 The CFA argument indicates the frame to which control is
6181 about to be transferred. HANDLER is the destination PC.
6183 We ignore the CFA and set a temporary breakpoint at HANDLER.
6184 This is not extremely efficient but it avoids issues in gdb
6185 with computing the DWARF CFA, and it also works even in weird
6186 cases such as throwing an exception from inside a signal
6187 handler. */
6191 {
6197 else
6198 {
6202 }
6203 }
6204 }
6206 {
6207 }
6208 END_CATCH
6209 }
6211 static void
6213 {
6219 /* Let callers know we don't want to wait for the inferior anymore. */
6221 }
6223 /* Called when we should continue running the inferior, because the
6224 current event doesn't cause a user visible stop. This does the
6225 resuming part; waiting for the next event is done elsewhere. */
6227 static void
6229 {
6230 /* Make sure normal_stop is called if we get a QUIT handled before
6231 reaching resume. */
6234 /* Save the pc before execution, to compare with pc after stop. */
6240 {
6241 /* We haven't yet gotten our trap, and either: intercepted a
6242 non-signal event (e.g., a fork); or took a signal which we
6243 are supposed to pass through to the inferior. Simply
6244 continue. */
6247 }
6248 else
6249 {
6254 /* Either the trap was not expected, but we are continuing
6255 anyway (if we got a signal, the user asked it be passed to
6256 the child)
6257 -- or --
6258 We got our expected trap, but decided we should resume from
6259 it.
6261 We're going to run this baby now!
6263 Note that insert_breakpoints won't try to re-insert
6264 already inserted breakpoints. Therefore, we don't
6265 care if breakpoints were already inserted, or not. */
6267 /* If we need to step over a breakpoint, and we're not using
6268 displaced stepping to do so, insert all breakpoints
6269 (watchpoints, etc.) but the one we're stepping over, step one
6270 instruction, and then re-insert the breakpoint when that step
6271 is finished. */
6278 /* We can't use displaced stepping if we need to step past a
6279 watchpoint. The instruction copied to the scratch pad would
6280 still trigger the watchpoint. */
6282 && (remove_wps
6284 {
6287 }
6290 else
6293 /* Stop stepping if inserting breakpoints fails. */
6294 TRY
6295 {
6297 }
6299 {
6304 }
6305 END_CATCH
6309 /* Do not deliver GDB_SIGNAL_TRAP (except when the user
6310 explicitly specifies that such a signal should be delivered
6311 to the target program). Typically, that would occur when a
6312 user is debugging a target monitor on a simulator: the target
6313 monitor sets a breakpoint; the simulator encounters this
6314 breakpoint and halts the simulation handing control to GDB;
6315 GDB, noting that the stop address doesn't map to any known
6316 breakpoint, returns control back to the simulator; the
6317 simulator then delivers the hardware equivalent of a
6318 GDB_SIGNAL_TRAP to the program being debugged. */
6325 }
6328 }
6330 /* This function normally comes after a resume, before
6331 handle_inferior_event exits. It takes care of any last bits of
6332 housekeeping, and sets the all-important wait_some_more flag. */
6334 static void
6336 {
6340 /* This is the old end of the while loop. Let everybody know we
6341 want to wait for the inferior some more and get called again
6342 soon. */
6344 }
6346 /* We are done with the step range of a step/next/si/ni command.
6347 Called once for each n of a "step n" operation. */
6349 static void
6351 {
6354 }
6356 /* Several print_*_reason functions to print why the inferior has stopped.
6357 We always print something when the inferior exits, or receives a signal.
6358 The rest of the cases are dealt with later on in normal_stop and
6359 print_it_typical. Ideally there should be a call to one of these
6360 print_*_reason functions functions from handle_inferior_event each time
6361 stop_waiting is called.
6363 Note that we don't call these directly, instead we delegate that to
6364 the interpreters, through observers. Interpreters then call these
6365 with whatever uiout is right. */
6367 void
6369 {
6370 /* For CLI-like interpreters, print nothing. */
6373 {
6376 }
6377 }
6379 void
6381 {
6384 ui_out_field_string
6398 }
6400 void
6402 {
6408 {
6419 }
6420 else
6421 {
6423 ui_out_field_string
6430 }
6431 }
6433 void
6435 {
6439 {
6447 }
6448 else
6449 {
6453 ui_out_field_string
6463 }
6465 }
6467 void
6469 {
6471 }
6473 /* Print current location without a level number, if we have changed
6474 functions or hit a breakpoint. Print source line if we have one.
6475 bpstat_print contains the logic deciding in detail what to print,
6476 based on the event(s) that just occurred. */
6478 void
6480 {
6488 {
6490 /* FIXME: cagney/2002-12-01: Given that a frame ID does (or
6491 should) carry around the function and does (or should) use
6492 that when doing a frame comparison. */
6497 {
6498 /* Finished step, just print source line. */
6500 }
6501 else
6502 {
6503 /* Print location and source line. */
6505 }
6508 /* Print location and source line. */
6515 /* Something bogus. */
6521 }
6523 /* The behavior of this routine with respect to the source
6524 flag is:
6525 SRC_LINE: Print only source line
6526 LOCATION: Print only location
6527 SRC_AND_LOC: Print location and source line. */
6531 /* Display the auto-display expressions. */
6533 }
6535 /* Here to return control to GDB when the inferior stops for real.
6536 Print appropriate messages, remove breakpoints, give terminal our modes.
6538 STOP_PRINT_FRAME nonzero means print the executing frame
6539 (pc, function, args, file, line number and line text).
6540 BREAKPOINTS_FAILED nonzero means stop was due to error
6541 attempting to insert breakpoints. */
6543 void
6545 {
6547 ptid_t last_ptid;
6552 /* If an exception is thrown from this point on, make sure to
6553 propagate GDB's knowledge of the executing state to the
6554 frontend/user running state. A QUIT is an easy exception to see
6555 here, so do this before any filtered output. */
6563 /* As we're presenting a stop, and potentially removing breakpoints,
6564 update the thread list so we can tell whether there are threads
6565 running on the target. With target remote, for example, we can
6566 only learn about new threads when we explicitly update the thread
6567 list. Do this before notifying the interpreters about signal
6568 stops, end of stepping ranges, etc., so that the "new thread"
6569 output is emitted before e.g., "Program received signal FOO",
6570 instead of after. */
6576 /* As with the notification of thread events, we want to delay
6577 notifying the user that we've switched thread context until
6578 the inferior actually stops.
6580 There's no point in saying anything if the inferior has exited.
6581 Note that SIGNALLED here means "exited with a signal", not
6582 "received a signal".
6584 Also skip saying anything in non-stop mode. In that mode, as we
6585 don't want GDB to switch threads behind the user's back, to avoid
6586 races where the user is typing a command to apply to thread x,
6587 but GDB switches to thread y before the user finishes entering
6588 the command, fetch_inferior_event installs a cleanup to restore
6589 the current thread back to the thread the user had selected right
6590 after this event is handled, so we're not really switching, only
6591 informing of a stop. */
6594 && target_has_execution
6598 {
6604 }
6607 {
6612 }
6614 /* Note: this depends on the update_thread_list call above. */
6616 {
6618 {
6623 }
6624 }
6626 /* If an auto-display called a function and that got a signal,
6627 delete that auto-display to avoid an infinite recursion. */
6632 /* Notify observers if we finished a "step"-like command, etc. */
6637 {
6638 /* But not if in the middle of doing a "step n" operation for
6639 n > 1 */
6644 }
6649 /* Set the current source location. This will also happen if we
6650 display the frame below, but the current SAL will be incorrect
6651 during a user hook-stop function. */
6655 /* Let the user/frontend see the threads as stopped, but do nothing
6656 if the thread was running an infcall. We may be e.g., evaluating
6657 a breakpoint condition. In that case, the thread had state
6658 THREAD_RUNNING before the infcall, and shall remain set to
6659 running, all without informing the user/frontend about state
6660 transition changes. If this is actually a call command, then the
6661 thread was originally already stopped, so there's no state to
6662 finish either. */
6665 else
6668 /* Look up the hook_stop and run it (CLI internally handles problem
6669 of stop_command's pre-hook not existing). */
6681 /* Select innermost stack frame - i.e., current frame is frame 0,
6682 and current location is based on that.
6683 Don't do this on return from a stack dummy routine,
6684 or if the program has exited. */
6687 {
6690 /* If --batch-silent is enabled then there's no need to print the current
6691 source location, and to try risks causing an error message about
6692 missing source files. */
6695 }
6697 /* Save the function value return registers, if we care.
6698 We might be about to restore their previous contents. */
6701 {
6702 /* This should not be necessary. */
6706 /* NB: The copy goes through to the target picking up the value of
6707 all the registers. */
6709 }
6712 {
6713 /* Pop the empty frame that contains the stack dummy.
6714 This also restores inferior state prior to the call
6715 (struct infcall_suspend_state). */
6720 /* frame_pop() calls reinit_frame_cache as the last thing it
6721 does which means there's currently no selected frame. We
6722 don't need to re-establish a selected frame if the dummy call
6723 returns normally, that will be done by
6724 restore_infcall_control_state. However, we do have to handle
6725 the case where the dummy call is returning after being
6726 stopped (e.g. the dummy call previously hit a breakpoint).
6727 We can't know which case we have so just always re-establish
6728 a selected frame here. */
6730 }
6732 done:
6735 /* Suppress the stop observer if we're in the middle of:
6737 - a step n (n > 1), as there still more steps to be done.
6739 - a "finish" command, as the observer will be called in
6740 finish_command_continuation, so it can include the inferior
6741 function's return value.
6743 - calling an inferior function, as we pretend we inferior didn't
6744 run at all. The return value of the call is handled by the
6745 expression evaluator, through call_function_by_hand. */
6756 {
6759 stop_print_frame);
6760 else
6762 }
6765 {
6768 /* Delete the breakpoint we stopped at, if it wants to be deleted.
6769 Delete any breakpoint that is to be deleted at the next stop. */
6771 }
6773 /* Try to get rid of automatically added inferiors that are no
6774 longer needed. Keeping those around slows down things linearly.
6775 Note that this never removes the current inferior. */
6777 }
6779 static int
6781 {
6784 }
6785 \f
6786 int
6788 {
6790 }
6792 int
6794 {
6796 }
6798 int
6800 {
6802 }
6804 static void
6806 {
6808 {
6813 }
6819 }
6821 int
6823 {
6829 }
6831 int
6833 {
6839 }
6841 int
6843 {
6849 }
6851 /* Update the global 'signal_catch' from INFO and notify the
6852 target. */
6854 void
6856 {
6863 }
6865 static void
6867 {
6870 }
6872 static void
6874 {
6887 }
6889 /* Specify how various signals in the inferior should be handled. */
6891 static void
6893 {
6904 {
6906 }
6908 /* Allocate and zero an array of flags for which signals to handle. */
6914 /* Break the command line up into args. */
6919 /* Walk through the args, looking for signal oursigs, signal names, and
6920 actions. Signal numbers and signal names may be interspersed with
6921 actions, with the actions being performed for all signals cumulatively
6922 specified. Signal ranges can be specified as <LOW>-<HIGH>. */
6925 {
6928 {;
6929 }
6934 {
6935 /* Apply action to all signals except those used by the
6936 debugger. Silently skip those. */
6940 }
6942 {
6945 }
6947 {
6949 }
6951 {
6953 }
6955 {
6957 }
6959 {
6961 }
6963 {
6965 }
6967 {
6970 }
6972 {
6974 }
6976 {
6977 /* It is numeric. The numeric signal refers to our own
6978 internal signal numbering from target.h, not to host/target
6979 signal number. This is a feature; users really should be
6980 using symbolic names anyway, and the common ones like
6981 SIGHUP, SIGINT, SIGALRM, etc. will work right anyway. */
6986 {
6989 }
6991 {
6992 /* Bet he didn't figure we'd think of this case... */
6996 }
6997 }
6998 else
6999 {
7002 {
7004 }
7005 else
7006 {
7007 /* Not a number and not a recognized flag word => complain. */
7009 }
7010 }
7012 /* If any signal numbers or symbol names were found, set flags for
7013 which signals to apply actions to. */
7016 {
7018 {
7022 {
7026 {
7028 }
7029 else
7030 {
7033 }
7034 }
7039 /* Make sure that "all" doesn't print these. */
7044 }
7045 }
7047 argv++;
7048 }
7052 {
7058 {
7059 /* Show the results. */
7064 }
7067 }
7070 }
7072 /* Complete the "handle" command. */
7077 {
7080 {
7090 NULL,
7091 };
7100 }
7102 enum gdb_signal
7104 {
7109 }
7111 /* Print current contents of the tables set by the handle command.
7112 It is possible we should just be printing signals actually used
7113 by the current target (but for things to work right when switching
7114 targets, all signals should be in the signal tables). */
7116 static void
7118 {
7124 {
7125 /* First see if this is a symbol name. */
7128 {
7129 /* No, try numeric. */
7130 oursig =
7132 }
7135 }
7138 /* These ugly casts brought to you by the native VAX compiler. */
7142 {
7143 QUIT;
7148 }
7152 }
7154 /* Check if it makes sense to read $_siginfo from the current thread
7155 at this point. If not, throw an error. */
7157 static void
7159 {
7160 /* No current inferior, no siginfo. */
7164 /* Don't try to read from a dead thread. */
7168 /* ... or from a spinning thread. */
7171 }
7173 /* The $_siginfo convenience variable is a bit special. We don't know
7174 for sure the type of the value until we actually have a chance to
7175 fetch the data. The type can change depending on gdbarch, so it is
7176 also dependent on which thread you have selected.
7178 1. making $_siginfo be an internalvar that creates a new value on
7179 access.
7181 2. making the value of $_siginfo be an lval_computed value. */
7183 /* This function implements the lval_computed support for reading a
7184 $_siginfo value. */
7186 static void
7188 {
7189 LONGEST transferred;
7193 transferred =
7195 NULL,
7202 }
7204 /* This function implements the lval_computed support for writing a
7205 $_siginfo value. */
7207 static void
7209 {
7210 LONGEST transferred;
7215 TARGET_OBJECT_SIGNAL_INFO,
7216 NULL,
7223 }
7226 {
7227 siginfo_value_read,
7228 siginfo_value_write
7229 };
7231 /* Return a new value with the correct type for the siginfo object of
7232 the current thread using architecture GDBARCH. Return a void value
7233 if there's no object available. */
7238 {
7242 {
7246 }
7249 }
7251 \f
7252 /* infcall_suspend_state contains state about the program itself like its
7253 registers and any signal it received when it last stopped.
7254 This state must be restored regardless of how the inferior function call
7255 ends (either successfully, or after it hits a breakpoint or signal)
7256 if the program is to properly continue where it left off. */
7258 struct infcall_suspend_state
7259 {
7263 #endif
7265 /* Other fields: */
7266 CORE_ADDR stop_pc;
7269 /* Format of SIGINFO_DATA or NULL if it is not present. */
7272 /* The inferior format depends on SIGINFO_GDBARCH and it has a length of
7273 TYPE_LENGTH (gdbarch_get_siginfo_type ()). For different gdbarch the
7274 content would be invalid. */
7276 };
7280 {
7283 #if 0
7285 #endif
7291 {
7302 else
7303 {
7304 /* Errors ignored. */
7307 }
7308 }
7313 {
7316 }
7321 #endif
7323 /* run_inferior_call will not use the signal due to its `proceed' call with
7324 GDB_SIGNAL_0 anyway. */
7332 }
7334 /* Restore inferior session state to INF_STATE. */
7336 void
7338 {
7340 #if 0
7342 #endif
7349 #endif
7354 {
7357 /* Errors ignored. */
7360 }
7362 /* The inferior can be gone if the user types "print exit(0)"
7363 (and perhaps other times). */
7365 /* NB: The register write goes through to the target. */
7369 }
7371 static void
7373 {
7375 }
7378 make_cleanup_restore_infcall_suspend_state
7380 {
7382 }
7384 void
7386 {
7390 }
7394 {
7396 }
7398 /* infcall_control_state contains state regarding gdb's control of the
7399 inferior itself like stepping control. It also contains session state like
7400 the user's currently selected frame. */
7402 struct infcall_control_state
7403 {
7407 /* Other fields: */
7412 /* ID if the selected frame when the inferior function call was made. */
7414 };
7416 /* Save all of the information associated with the inferior<==>gdb
7417 connection. */
7421 {
7432 /* Save original bpstat chain to INF_STATUS; replace it in TP with copy of
7433 chain. If caller's caller is walking the chain, they'll be happier if we
7434 hand them back the original chain when restore_infcall_control_state is
7435 called. */
7438 /* Other fields: */
7446 }
7448 static int
7450 {
7456 /* If inf_status->selected_frame_id is NULL, there was no previously
7457 selected frame. */
7459 {
7462 }
7467 }
7469 /* Restore inferior session state to INF_STATUS. */
7471 void
7473 {
7484 /* Handle the bpstat_copy of the chain. */
7490 /* Other fields: */
7496 {
7497 /* The point of catch_errors is that if the stack is clobbered,
7498 walking the stack might encounter a garbage pointer and
7499 error() trying to dereference it. */
7504 /* Error in restoring the selected frame. Select the innermost
7505 frame. */
7507 }
7510 }
7512 static void
7514 {
7516 }
7519 make_cleanup_restore_infcall_control_state
7521 {
7523 }
7525 void
7527 {
7536 /* See save_infcall_control_state for info on stop_bpstat. */
7540 }
7541 \f
7542 /* restore_inferior_ptid() will be used by the cleanup machinery
7543 to restore the inferior_ptid value saved in a call to
7544 save_inferior_ptid(). */
7546 static void
7548 {
7553 }
7555 /* Save the value of inferior_ptid so that it may be restored by a
7556 later call to do_cleanups(). Returns the struct cleanup pointer
7557 needed for later doing the cleanup. */
7561 {
7567 }
7569 /* See infrun.h. */
7571 void
7573 {
7576 }
7577 \f
7579 /* User interface for reverse debugging:
7580 Set exec-direction / show exec-direction commands
7581 (returns error unless target implements to_set_exec_direction method). */
7588 exec_forward,
7589 exec_reverse,
7590 NULL
7591 };
7593 static void
7596 {
7598 {
7603 }
7604 else
7605 {
7608 }
7609 }
7611 static void
7614 {
7626 }
7627 }
7629 static void
7632 {
7635 }
7637 /* Implementation of `siginfo' variable. */
7640 {
7641 siginfo_make_value,
7642 NULL,
7643 NULL
7644 };
7646 void
7648 {
7695 NULL,
7696 show_debug_infrun,
7704 NULL,
7705 show_debug_displaced,
7723 set_non_stop,
7724 show_non_stop,
7739 {
7744 }
7746 /* Signals caused by debugger's own actions
7747 should not be given to the program afterwards. */
7751 /* Signals that are not errors should not normally enter the debugger. */
7771 /* These signals are used internally by user-level thread
7772 implementations. (See signal(5) on Solaris.) Like the above
7773 signals, a healthy program receives and handles them as part of
7774 its normal operation. */
7782 /* Update cached state. */
7792 set_stop_on_solib_events,
7793 show_stop_on_solib_events,
7797 follow_fork_mode_kind_names,
7806 NULL,
7807 show_follow_fork_mode_string,
7811 follow_exec_mode_names,
7830 NULL,
7831 show_follow_exec_mode_string,
7843 show_scheduler_mode,
7854 NULL,
7855 show_schedule_multiple,
7864 NULL,
7865 show_step_stop_if_no_debug,
7878 NULL,
7879 show_can_use_displaced_stepping,
7890 /* Set/show detach-on-fork: user-settable mode. */
7898 /* Set/show disable address space randomization mode. */
7911 /* ptid initializations */
7920 /* Explicitly create without lookup, since that tries to create a
7921 value with a void typed value, and when we get here, gdbarch
7922 isn't initialized yet. At this point, we're quite sure there
7923 isn't another convenience variable of the same name. */
7934 set_observer_mode,
7935 show_observer_mode,
7938 }