1 /* Multi-process/thread control defs for GDB, the GNU debugger.
2 Copyright (C) 1987-2016 Free Software Foundation, Inc.
3 Contributed by Lynx Real-Time Systems, Inc. Los Gatos, CA.
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/>. */
26 #include "breakpoint.h"
31 #include "common/vec.h"
32 #include "target/waitstatus.h"
33 #include "cli/cli-utils.h"
35 /* Frontend view of the thread state. Possible extensions: stepping,
36 finishing, until(ling),... */
44 /* Inferior thread specific part of `struct infcall_control_state'.
46 Inferior process counterpart is `struct inferior_control_state'. */
48 struct thread_control_state
50 /* User/external stepping state. */
52 /* Step-resume or longjmp-resume breakpoint. */
53 struct breakpoint *step_resume_breakpoint;
55 /* Exception-resume breakpoint. */
56 struct breakpoint *exception_resume_breakpoint;
58 /* Breakpoints used for software single stepping. Plural, because
59 it may have multiple locations. E.g., if stepping over a
60 conditional branch instruction we can't decode the condition for,
61 we'll need to put a breakpoint at the branch destination, and
62 another at the instruction after the branch. */
63 struct breakpoint *single_step_breakpoints;
65 /* Range to single step within.
67 If this is nonzero, respond to a single-step signal by continuing
68 to step if the pc is in this range.
70 If step_range_start and step_range_end are both 1, it means to
71 step for a single instruction (FIXME: it might clean up
72 wait_for_inferior in a minor way if this were changed to the
73 address of the instruction and that address plus one. But maybe
75 CORE_ADDR step_range_start; /* Inclusive */
76 CORE_ADDR step_range_end; /* Exclusive */
78 /* Function the thread was in as of last it started stepping. */
79 struct symbol *step_start_function;
81 /* If GDB issues a target step request, and this is nonzero, the
82 target should single-step this thread once, and then continue
83 single-stepping it without GDB core involvement as long as the
84 thread stops in the step range above. If this is zero, the
85 target should ignore the step range, and only issue one single
89 /* Stack frame address as of when stepping command was issued.
90 This is how we know when we step into a subroutine call, and how
91 to set the frame for the breakpoint used to step out. */
92 struct frame_id step_frame_id;
94 /* Similarly, the frame ID of the underlying stack frame (skipping
95 any inlined frames). */
96 struct frame_id step_stack_frame_id;
98 /* Nonzero if we are presently stepping over a breakpoint.
100 If we hit a breakpoint or watchpoint, and then continue, we need
101 to single step the current thread with breakpoints disabled, to
102 avoid hitting the same breakpoint or watchpoint again. And we
103 should step just a single thread and keep other threads stopped,
104 so that other threads don't miss breakpoints while they are
107 So, this variable simultaneously means that we need to single
108 step the current thread, keep other threads stopped, and that
109 breakpoints should be removed while we step.
111 This variable is set either:
112 - in proceed, when we resume inferior on user's explicit request
113 - in keep_going, if handle_inferior_event decides we need to
114 step over breakpoint.
116 The variable is cleared in normal_stop. The proceed calls
117 wait_for_inferior, which calls handle_inferior_event in a loop,
118 and until wait_for_inferior exits, this variable is changed only
122 /* Nonzero if the thread is being proceeded for a "finish" command
123 or a similar situation when return value should be printed. */
124 int proceed_to_finish;
126 /* Nonzero if the thread is being proceeded for an inferior function
130 enum step_over_calls_kind step_over_calls;
132 /* Nonzero if stopped due to a step command. */
135 /* Chain containing status of breakpoint(s) the thread stopped
139 /* The interpreter that issued the execution command. NULL if the
140 thread was resumed as a result of a command applied to some other
141 thread (e.g., "next" with scheduler-locking off). */
142 struct interp *command_interp;
144 /* Whether the command that started the thread was a stepping
145 command. This is used to decide whether "set scheduler-locking
146 step" behaves like "on" or "off". */
147 int stepping_command;
150 /* Inferior thread specific part of `struct infcall_suspend_state'. */
152 struct thread_suspend_state
154 /* Last signal that the inferior received (why it stopped). When
155 the thread is resumed, this signal is delivered. Note: the
156 target should not check whether the signal is in pass state,
157 because the signal may have been explicitly passed with the
158 "signal" command, which overrides "handle nopass". If the signal
159 should be suppressed, the core will take care of clearing this
160 before the target is resumed. */
161 enum gdb_signal stop_signal;
163 /* The reason the thread last stopped, if we need to track it
164 (breakpoint, watchpoint, etc.) */
165 enum target_stop_reason stop_reason;
167 /* The waitstatus for this thread's last event. */
168 struct target_waitstatus waitstatus;
169 /* If true WAITSTATUS hasn't been handled yet. */
170 int waitstatus_pending_p;
172 /* Record the pc of the thread the last time it stopped. (This is
173 not the current thread's PC as that may have changed since the
174 last stop, e.g., "return" command, or "p $pc = 0xf000"). This is
175 used in coordination with stop_reason and waitstatus_pending_p:
176 if the thread's PC is changed since it last stopped, a pending
177 breakpoint waitstatus is discarded. */
181 typedef struct value *value_ptr;
182 DEF_VEC_P (value_ptr);
183 typedef VEC (value_ptr) value_vec;
187 struct thread_info *next;
188 ptid_t ptid; /* "Actual process id";
189 In fact, this may be overloaded with
190 kernel thread id, etc. */
192 /* Each thread has two GDB IDs.
194 a) The thread ID (Id). This consists of the pair of:
196 - the number of the thread's inferior and,
198 - the thread's thread number in its inferior, aka, the
199 per-inferior thread number. This number is unique in the
200 inferior but not unique between inferiors.
202 b) The global ID (GId). This is a a single integer unique
203 between all inferiors.
207 (gdb) info threads -gid
208 Id GId Target Id Frame
209 * 1.1 1 Thread A 0x16a09237 in foo () at foo.c:10
210 1.2 3 Thread B 0x15ebc6ed in bar () at foo.c:20
211 1.3 5 Thread C 0x15ebc6ed in bar () at foo.c:20
212 2.1 2 Thread A 0x16a09237 in foo () at foo.c:10
213 2.2 4 Thread B 0x15ebc6ed in bar () at foo.c:20
214 2.3 6 Thread C 0x15ebc6ed in bar () at foo.c:20
216 Above, both inferiors 1 and 2 have threads numbered 1-3, but each
217 thread has its own unique global ID. */
219 /* The thread's global GDB thread number. This is exposed to MI and
223 /* The per-inferior thread number. This is unique in the inferior
224 the thread belongs to, but not unique between inferiors. This is
225 what the $_thread convenience variable is bound to. */
228 /* The inferior this thread belongs to. */
229 struct inferior *inf;
231 /* The name of the thread, as specified by the user. This is NULL
232 if the thread does not have a user-given name. */
235 /* Non-zero means the thread is executing. Note: this is different
236 from saying that there is an active target and we are stopped at
237 a breakpoint, for instance. This is a real indicator whether the
238 thread is off and running. */
241 /* Non-zero if this thread is resumed from infrun's perspective.
242 Note that a thread can be marked both as not-executing and
243 resumed at the same time. This happens if we try to resume a
244 thread that has a wait status pending. We shouldn't let the
245 thread really run until that wait status has been processed, but
246 we should not process that wait status if we didn't try to let
250 /* Frontend view of the thread state. Note that the THREAD_RUNNING/
251 THREAD_STOPPED states are different from EXECUTING. When the
252 thread is stopped internally while handling an internal event,
253 like a software single-step breakpoint, EXECUTING will be false,
254 but STATE will still be THREAD_RUNNING. */
255 enum thread_state state;
257 /* If this is > 0, then it means there's code out there that relies
258 on this thread being listed. Don't delete it from the lists even
259 if we detect it exiting. */
262 /* State of GDB control of inferior thread execution.
263 See `struct thread_control_state'. */
264 struct thread_control_state control;
266 /* State of inferior thread to restore after GDB is done with an inferior
267 call. See `struct thread_suspend_state'. */
268 struct thread_suspend_state suspend;
271 struct symtab *current_symtab;
273 /* Internal stepping state. */
275 /* Record the pc of the thread the last time it was resumed. (It
276 can't be done on stop as the PC may change since the last stop,
277 e.g., "return" command, or "p $pc = 0xf000"). This is maintained
278 by proceed and keep_going, and among other things, it's used in
279 adjust_pc_after_break to distinguish a hardware single-step
280 SIGTRAP from a breakpoint SIGTRAP. */
283 /* Did we set the thread stepping a breakpoint instruction? This is
284 used in conjunction with PREV_PC to decide whether to adjust the
286 int stepped_breakpoint;
288 /* Should we step over breakpoint next time keep_going is called? */
289 int stepping_over_breakpoint;
291 /* Should we step over a watchpoint next time keep_going is called?
292 This is needed on targets with non-continuable, non-steppable
294 int stepping_over_watchpoint;
296 /* Set to TRUE if we should finish single-stepping over a breakpoint
297 after hitting the current step-resume breakpoint. The context here
298 is that GDB is to do `next' or `step' while signal arrives.
299 When stepping over a breakpoint and signal arrives, GDB will attempt
300 to skip signal handler, so it inserts a step_resume_breakpoint at the
301 signal return address, and resume inferior.
302 step_after_step_resume_breakpoint is set to TRUE at this moment in
303 order to keep GDB in mind that there is still a breakpoint to step over
304 when GDB gets back SIGTRAP from step_resume_breakpoint. */
305 int step_after_step_resume_breakpoint;
307 /* Pointer to the state machine manager object that handles what is
308 left to do for the thread's execution command after the target
309 stops. Several execution commands use it. */
310 struct thread_fsm *thread_fsm;
312 /* This is used to remember when a fork or vfork event was caught by
313 a catchpoint, and thus the event is to be followed at the next
314 resume of the thread, and not immediately. */
315 struct target_waitstatus pending_follow;
317 /* True if this thread has been explicitly requested to stop. */
320 /* The initiating frame of a nexting operation, used for deciding
321 which exceptions to intercept. If it is null_frame_id no
322 bp_longjmp or bp_exception but longjmp has been caught just for
323 bp_longjmp_call_dummy. */
324 struct frame_id initiating_frame;
326 /* Private data used by the target vector implementation. */
327 struct private_thread_info *priv;
329 /* Function that is called to free PRIVATE. If this is NULL, then
330 xfree will be called on PRIVATE. */
331 void (*private_dtor) (struct private_thread_info *);
333 /* Branch trace information for this thread. */
334 struct btrace_thread_info btrace;
336 /* Flag which indicates that the stack temporaries should be stored while
337 evaluating expressions. */
338 int stack_temporaries_enabled;
340 /* Values that are stored as temporaries on stack while evaluating
342 value_vec *stack_temporaries;
344 /* Step-over chain. A thread is in the step-over queue if these are
345 non-NULL. If only a single thread is in the chain, then these
346 fields point to self. */
347 struct thread_info *step_over_prev;
348 struct thread_info *step_over_next;
351 /* Create an empty thread list, or empty the existing one. */
352 extern void init_thread_list (void);
354 /* Add a thread to the thread list, print a message
355 that a new thread is found, and return the pointer to
356 the new thread. Caller my use this pointer to
357 initialize the private thread data. */
358 extern struct thread_info *add_thread (ptid_t ptid);
360 /* Same as add_thread, but does not print a message
362 extern struct thread_info *add_thread_silent (ptid_t ptid);
364 /* Same as add_thread, and sets the private info. */
365 extern struct thread_info *add_thread_with_info (ptid_t ptid,
366 struct private_thread_info *);
368 /* Delete an existing thread list entry. */
369 extern void delete_thread (ptid_t);
371 /* Delete an existing thread list entry, and be quiet about it. Used
372 after the process this thread having belonged to having already
373 exited, for example. */
374 extern void delete_thread_silent (ptid_t);
376 /* Delete a step_resume_breakpoint from the thread database. */
377 extern void delete_step_resume_breakpoint (struct thread_info *);
379 /* Delete an exception_resume_breakpoint from the thread database. */
380 extern void delete_exception_resume_breakpoint (struct thread_info *);
382 /* Delete the single-step breakpoints of thread TP, if any. */
383 extern void delete_single_step_breakpoints (struct thread_info *tp);
385 /* Check if the thread has software single stepping breakpoints
387 extern int thread_has_single_step_breakpoints_set (struct thread_info *tp);
389 /* Check whether the thread has software single stepping breakpoints
391 extern int thread_has_single_step_breakpoint_here (struct thread_info *tp,
392 struct address_space *aspace,
395 /* Translate the global integer thread id (GDB's homegrown id, not the
396 system's) into a "pid" (which may be overloaded with extra thread
398 extern ptid_t global_thread_id_to_ptid (int num);
400 /* Translate a 'pid' (which may be overloaded with extra thread
401 information) into the global integer thread id (GDB's homegrown id,
402 not the system's). */
403 extern int ptid_to_global_thread_id (ptid_t ptid);
405 /* Returns whether to show inferior-qualified thread IDs, or plain
406 thread numbers. Inferior-qualified IDs are shown whenever we have
407 multiple inferiors, or the only inferior left has number > 1. */
408 extern int show_inferior_qualified_tids (void);
410 /* Return a string version of THR's thread ID. If there are multiple
411 inferiors, then this prints the inferior-qualifier form, otherwise
412 it only prints the thread number. The result is stored in a
413 circular static buffer, NUMCELLS deep. */
414 const char *print_thread_id (struct thread_info *thr);
416 /* Boolean test for an already-known pid (which may be overloaded with
417 extra thread information). */
418 extern int in_thread_list (ptid_t ptid);
420 /* Boolean test for an already-known global thread id (GDB's homegrown
421 global id, not the system's). */
422 extern int valid_global_thread_id (int global_id);
424 /* Search function to lookup a thread by 'pid'. */
425 extern struct thread_info *find_thread_ptid (ptid_t ptid);
427 /* Find thread by GDB global thread ID. */
428 struct thread_info *find_thread_global_id (int global_id);
430 /* Finds the first thread of the inferior given by PID. If PID is -1,
431 returns the first thread in the list. */
432 struct thread_info *first_thread_of_process (int pid);
434 /* Returns any thread of process PID, giving preference to the current
436 extern struct thread_info *any_thread_of_process (int pid);
438 /* Returns any non-exited thread of process PID, giving preference to
439 the current thread, and to not executing threads. */
440 extern struct thread_info *any_live_thread_of_process (int pid);
442 /* Change the ptid of thread OLD_PTID to NEW_PTID. */
443 void thread_change_ptid (ptid_t old_ptid, ptid_t new_ptid);
445 /* Iterator function to call a user-provided callback function
446 once for each known thread. */
447 typedef int (*thread_callback_func) (struct thread_info *, void *);
448 extern struct thread_info *iterate_over_threads (thread_callback_func, void *);
450 /* Traverse all threads. */
451 #define ALL_THREADS(T) \
452 for (T = thread_list; T; T = T->next) \
454 /* Traverse over all threads, sorted by inferior. */
455 #define ALL_THREADS_BY_INFERIOR(inf, tp) \
456 ALL_INFERIORS (inf) \
460 /* Traverse all threads, except those that have THREAD_EXITED
463 #define ALL_NON_EXITED_THREADS(T) \
464 for (T = thread_list; T; T = T->next) \
465 if ((T)->state != THREAD_EXITED)
467 /* Traverse all threads, including those that have THREAD_EXITED
468 state. Allows deleting the currently iterated thread. */
469 #define ALL_THREADS_SAFE(T, TMP) \
470 for ((T) = thread_list; \
471 (T) != NULL ? ((TMP) = (T)->next, 1): 0; \
474 extern int thread_count (void);
476 /* Switch from one thread to another. Also sets the STOP_PC
478 extern void switch_to_thread (ptid_t ptid);
480 /* Switch from one thread to another. Does not read registers and
481 sets STOP_PC to -1. */
482 extern void switch_to_thread_no_regs (struct thread_info *thread);
484 /* Marks or clears thread(s) PTID as resumed. If PTID is
485 MINUS_ONE_PTID, applies to all threads. If ptid_is_pid(PTID) is
486 true, applies to all threads of the process pointed at by PTID. */
487 extern void set_resumed (ptid_t ptid, int resumed);
489 /* Marks thread PTID is running, or stopped.
490 If PTID is minus_one_ptid, marks all threads. */
491 extern void set_running (ptid_t ptid, int running);
493 /* Marks or clears thread(s) PTID as having been requested to stop.
494 If PTID is MINUS_ONE_PTID, applies to all threads. If
495 ptid_is_pid(PTID) is true, applies to all threads of the process
496 pointed at by PTID. If STOP, then the THREAD_STOP_REQUESTED
497 observer is called with PTID as argument. */
498 extern void set_stop_requested (ptid_t ptid, int stop);
500 /* NOTE: Since the thread state is not a boolean, most times, you do
501 not want to check it with negation. If you really want to check if
502 the thread is stopped,
506 if (is_stopped (ptid))
510 if (!is_running (ptid))
512 The latter also returns true on exited threads, most likelly not
515 /* Reports if in the frontend's perpective, thread PTID is running. */
516 extern int is_running (ptid_t ptid);
518 /* Is this thread listed, but known to have exited? We keep it listed
519 (but not visible) until it's safe to delete. */
520 extern int is_exited (ptid_t ptid);
522 /* In the frontend's perpective, is this thread stopped? */
523 extern int is_stopped (ptid_t ptid);
525 /* Marks thread PTID as executing, or not. If PTID is minus_one_ptid,
528 Note that this is different from the running state. See the
529 description of state and executing fields of struct
531 extern void set_executing (ptid_t ptid, int executing);
533 /* Reports if thread PTID is executing. */
534 extern int is_executing (ptid_t ptid);
536 /* True if any (known or unknown) thread is or may be executing. */
537 extern int threads_are_executing (void);
539 /* Merge the executing property of thread PTID over to its thread
540 state property (frontend running/stopped view).
542 "not executing" -> "stopped"
543 "executing" -> "running"
546 If PTID is minus_one_ptid, go over all threads.
548 Notifications are only emitted if the thread state did change. */
549 extern void finish_thread_state (ptid_t ptid);
551 /* Same as FINISH_THREAD_STATE, but with an interface suitable to be
552 registered as a cleanup. PTID_P points to the ptid_t that is
553 passed to FINISH_THREAD_STATE. */
554 extern void finish_thread_state_cleanup (void *ptid_p);
556 /* Commands with a prefix of `thread'. */
557 extern struct cmd_list_element *thread_cmd_list;
559 extern void thread_command (char *tidstr, int from_tty);
561 /* Print notices on thread events (attach, detach, etc.), set with
562 `set print thread-events'. */
563 extern int print_thread_events;
565 /* Prints the list of threads and their details on UIOUT. If
566 REQUESTED_THREADS, a list of GDB ids/ranges, is not NULL, only
567 print threads whose ID is included in the list. If PID is not -1,
568 only print threads from the process PID. Otherwise, threads from
569 all attached PIDs are printed. If both REQUESTED_THREADS is not
570 NULL and PID is not -1, then the thread is printed if it belongs to
571 the specified process. Otherwise, an error is raised. */
572 extern void print_thread_info (struct ui_out *uiout, char *requested_threads,
575 extern struct cleanup *make_cleanup_restore_current_thread (void);
577 /* Returns a pointer into the thread_info corresponding to
578 INFERIOR_PTID. INFERIOR_PTID *must* be in the thread list. */
579 extern struct thread_info* inferior_thread (void);
581 extern void update_thread_list (void);
583 /* Delete any thread the target says is no longer alive. */
585 extern void prune_threads (void);
587 /* Delete threads marked THREAD_EXITED. Unlike prune_threads, this
588 does not consult the target about whether the thread is alive right
590 extern void delete_exited_threads (void);
592 /* Return true if PC is in the stepping range of THREAD. */
594 int pc_in_thread_step_range (CORE_ADDR pc, struct thread_info *thread);
596 extern struct cleanup *enable_thread_stack_temporaries (ptid_t ptid);
598 extern int thread_stack_temporaries_enabled_p (ptid_t ptid);
600 extern void push_thread_stack_temporary (ptid_t ptid, struct value *v);
602 extern struct value *get_last_thread_stack_temporary (ptid_t);
604 extern int value_in_thread_stack_temporaries (struct value *, ptid_t);
606 /* Add TP to the end of its inferior's pending step-over chain. */
608 extern void thread_step_over_chain_enqueue (struct thread_info *tp);
610 /* Remove TP from its inferior's pending step-over chain. */
612 extern void thread_step_over_chain_remove (struct thread_info *tp);
614 /* Return the next thread in the step-over chain starting at TP. NULL
615 if TP is the last entry in the chain. */
617 extern struct thread_info *thread_step_over_chain_next (struct thread_info *tp);
619 /* Return true if TP is in the step-over chain. */
621 extern int thread_is_in_step_over_chain (struct thread_info *tp);
623 /* Cancel any ongoing execution command. */
625 extern void thread_cancel_execution_command (struct thread_info *thr);
627 /* Check whether it makes sense to access a register of the current
628 thread at this point. If not, throw an error (e.g., the thread is
630 extern void validate_registers_access (void);
632 extern struct thread_info *thread_list;
634 #endif /* GDBTHREAD_H */