1 /* Multi-process/thread control defs for GDB, the GNU debugger.
2 Copyright (C) 1987-2017 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 /* Whether the command that started the thread was a stepping
140 command. This is used to decide whether "set scheduler-locking
141 step" behaves like "on" or "off". */
142 int stepping_command;
145 /* Inferior thread specific part of `struct infcall_suspend_state'. */
147 struct thread_suspend_state
149 /* Last signal that the inferior received (why it stopped). When
150 the thread is resumed, this signal is delivered. Note: the
151 target should not check whether the signal is in pass state,
152 because the signal may have been explicitly passed with the
153 "signal" command, which overrides "handle nopass". If the signal
154 should be suppressed, the core will take care of clearing this
155 before the target is resumed. */
156 enum gdb_signal stop_signal;
158 /* The reason the thread last stopped, if we need to track it
159 (breakpoint, watchpoint, etc.) */
160 enum target_stop_reason stop_reason;
162 /* The waitstatus for this thread's last event. */
163 struct target_waitstatus waitstatus;
164 /* If true WAITSTATUS hasn't been handled yet. */
165 int waitstatus_pending_p;
167 /* Record the pc of the thread the last time it stopped. (This is
168 not the current thread's PC as that may have changed since the
169 last stop, e.g., "return" command, or "p $pc = 0xf000"). This is
170 used in coordination with stop_reason and waitstatus_pending_p:
171 if the thread's PC is changed since it last stopped, a pending
172 breakpoint waitstatus is discarded. */
176 typedef struct value *value_ptr;
177 DEF_VEC_P (value_ptr);
178 typedef VEC (value_ptr) value_vec;
183 explicit thread_info (inferior *inf, ptid_t ptid);
186 bool deletable () const
188 /* If this is the current thread, or there's code out there that
189 relies on it existing (m_refcount > 0) we can't delete yet. */
190 return (m_refcount == 0 && !ptid_equal (ptid, inferior_ptid));
193 /* Increase the refcount. */
196 gdb_assert (m_refcount >= 0);
200 /* Decrease the refcount. */
204 gdb_assert (m_refcount >= 0);
207 struct thread_info *next = NULL;
208 ptid_t ptid; /* "Actual process id";
209 In fact, this may be overloaded with
210 kernel thread id, etc. */
212 /* Each thread has two GDB IDs.
214 a) The thread ID (Id). This consists of the pair of:
216 - the number of the thread's inferior and,
218 - the thread's thread number in its inferior, aka, the
219 per-inferior thread number. This number is unique in the
220 inferior but not unique between inferiors.
222 b) The global ID (GId). This is a a single integer unique
223 between all inferiors.
227 (gdb) info threads -gid
228 Id GId Target Id Frame
229 * 1.1 1 Thread A 0x16a09237 in foo () at foo.c:10
230 1.2 3 Thread B 0x15ebc6ed in bar () at foo.c:20
231 1.3 5 Thread C 0x15ebc6ed in bar () at foo.c:20
232 2.1 2 Thread A 0x16a09237 in foo () at foo.c:10
233 2.2 4 Thread B 0x15ebc6ed in bar () at foo.c:20
234 2.3 6 Thread C 0x15ebc6ed in bar () at foo.c:20
236 Above, both inferiors 1 and 2 have threads numbered 1-3, but each
237 thread has its own unique global ID. */
239 /* The thread's global GDB thread number. This is exposed to MI,
240 Python/Scheme, visible with "info threads -gid", and is also what
241 the $_gthread convenience variable is bound to. */
244 /* The per-inferior thread number. This is unique in the inferior
245 the thread belongs to, but not unique between inferiors. This is
246 what the $_thread convenience variable is bound to. */
249 /* The inferior this thread belongs to. */
250 struct inferior *inf;
252 /* The name of the thread, as specified by the user. This is NULL
253 if the thread does not have a user-given name. */
256 /* Non-zero means the thread is executing. Note: this is different
257 from saying that there is an active target and we are stopped at
258 a breakpoint, for instance. This is a real indicator whether the
259 thread is off and running. */
262 /* Non-zero if this thread is resumed from infrun's perspective.
263 Note that a thread can be marked both as not-executing and
264 resumed at the same time. This happens if we try to resume a
265 thread that has a wait status pending. We shouldn't let the
266 thread really run until that wait status has been processed, but
267 we should not process that wait status if we didn't try to let
271 /* Frontend view of the thread state. Note that the THREAD_RUNNING/
272 THREAD_STOPPED states are different from EXECUTING. When the
273 thread is stopped internally while handling an internal event,
274 like a software single-step breakpoint, EXECUTING will be false,
275 but STATE will still be THREAD_RUNNING. */
276 enum thread_state state = THREAD_STOPPED;
278 /* State of GDB control of inferior thread execution.
279 See `struct thread_control_state'. */
280 thread_control_state control {};
282 /* State of inferior thread to restore after GDB is done with an inferior
283 call. See `struct thread_suspend_state'. */
284 thread_suspend_state suspend {};
286 int current_line = 0;
287 struct symtab *current_symtab = NULL;
289 /* Internal stepping state. */
291 /* Record the pc of the thread the last time it was resumed. (It
292 can't be done on stop as the PC may change since the last stop,
293 e.g., "return" command, or "p $pc = 0xf000"). This is maintained
294 by proceed and keep_going, and among other things, it's used in
295 adjust_pc_after_break to distinguish a hardware single-step
296 SIGTRAP from a breakpoint SIGTRAP. */
297 CORE_ADDR prev_pc = 0;
299 /* Did we set the thread stepping a breakpoint instruction? This is
300 used in conjunction with PREV_PC to decide whether to adjust the
302 int stepped_breakpoint = 0;
304 /* Should we step over breakpoint next time keep_going is called? */
305 int stepping_over_breakpoint = 0;
307 /* Should we step over a watchpoint next time keep_going is called?
308 This is needed on targets with non-continuable, non-steppable
310 int stepping_over_watchpoint = 0;
312 /* Set to TRUE if we should finish single-stepping over a breakpoint
313 after hitting the current step-resume breakpoint. The context here
314 is that GDB is to do `next' or `step' while signal arrives.
315 When stepping over a breakpoint and signal arrives, GDB will attempt
316 to skip signal handler, so it inserts a step_resume_breakpoint at the
317 signal return address, and resume inferior.
318 step_after_step_resume_breakpoint is set to TRUE at this moment in
319 order to keep GDB in mind that there is still a breakpoint to step over
320 when GDB gets back SIGTRAP from step_resume_breakpoint. */
321 int step_after_step_resume_breakpoint = 0;
323 /* Pointer to the state machine manager object that handles what is
324 left to do for the thread's execution command after the target
325 stops. Several execution commands use it. */
326 struct thread_fsm *thread_fsm = NULL;
328 /* This is used to remember when a fork or vfork event was caught by
329 a catchpoint, and thus the event is to be followed at the next
330 resume of the thread, and not immediately. */
331 struct target_waitstatus pending_follow;
333 /* True if this thread has been explicitly requested to stop. */
334 int stop_requested = 0;
336 /* The initiating frame of a nexting operation, used for deciding
337 which exceptions to intercept. If it is null_frame_id no
338 bp_longjmp or bp_exception but longjmp has been caught just for
339 bp_longjmp_call_dummy. */
340 struct frame_id initiating_frame = null_frame_id;
342 /* Private data used by the target vector implementation. */
343 struct private_thread_info *priv = NULL;
345 /* Function that is called to free PRIVATE. If this is NULL, then
346 xfree will be called on PRIVATE. */
347 void (*private_dtor) (struct private_thread_info *) = NULL;
349 /* Branch trace information for this thread. */
350 struct btrace_thread_info btrace {};
352 /* Flag which indicates that the stack temporaries should be stored while
353 evaluating expressions. */
354 int stack_temporaries_enabled = 0;
356 /* Values that are stored as temporaries on stack while evaluating
358 value_vec *stack_temporaries = NULL;
360 /* Step-over chain. A thread is in the step-over queue if these are
361 non-NULL. If only a single thread is in the chain, then these
362 fields point to self. */
363 struct thread_info *step_over_prev = NULL;
364 struct thread_info *step_over_next = NULL;
368 /* If this is > 0, then it means there's code out there that relies
369 on this thread being listed. Don't delete it from the lists even
370 if we detect it exiting. */
374 /* Create an empty thread list, or empty the existing one. */
375 extern void init_thread_list (void);
377 /* Add a thread to the thread list, print a message
378 that a new thread is found, and return the pointer to
379 the new thread. Caller my use this pointer to
380 initialize the private thread data. */
381 extern struct thread_info *add_thread (ptid_t ptid);
383 /* Same as add_thread, but does not print a message
385 extern struct thread_info *add_thread_silent (ptid_t ptid);
387 /* Same as add_thread, and sets the private info. */
388 extern struct thread_info *add_thread_with_info (ptid_t ptid,
389 struct private_thread_info *);
391 /* Delete an existing thread list entry. */
392 extern void delete_thread (ptid_t);
394 /* Delete an existing thread list entry, and be quiet about it. Used
395 after the process this thread having belonged to having already
396 exited, for example. */
397 extern void delete_thread_silent (ptid_t);
399 /* Delete a step_resume_breakpoint from the thread database. */
400 extern void delete_step_resume_breakpoint (struct thread_info *);
402 /* Delete an exception_resume_breakpoint from the thread database. */
403 extern void delete_exception_resume_breakpoint (struct thread_info *);
405 /* Delete the single-step breakpoints of thread TP, if any. */
406 extern void delete_single_step_breakpoints (struct thread_info *tp);
408 /* Check if the thread has software single stepping breakpoints
410 extern int thread_has_single_step_breakpoints_set (struct thread_info *tp);
412 /* Check whether the thread has software single stepping breakpoints
414 extern int thread_has_single_step_breakpoint_here (struct thread_info *tp,
415 struct address_space *aspace,
418 /* Translate the global integer thread id (GDB's homegrown id, not the
419 system's) into a "pid" (which may be overloaded with extra thread
421 extern ptid_t global_thread_id_to_ptid (int num);
423 /* Translate a 'pid' (which may be overloaded with extra thread
424 information) into the global integer thread id (GDB's homegrown id,
425 not the system's). */
426 extern int ptid_to_global_thread_id (ptid_t ptid);
428 /* Returns whether to show inferior-qualified thread IDs, or plain
429 thread numbers. Inferior-qualified IDs are shown whenever we have
430 multiple inferiors, or the only inferior left has number > 1. */
431 extern int show_inferior_qualified_tids (void);
433 /* Return a string version of THR's thread ID. If there are multiple
434 inferiors, then this prints the inferior-qualifier form, otherwise
435 it only prints the thread number. The result is stored in a
436 circular static buffer, NUMCELLS deep. */
437 const char *print_thread_id (struct thread_info *thr);
439 /* Boolean test for an already-known pid (which may be overloaded with
440 extra thread information). */
441 extern int in_thread_list (ptid_t ptid);
443 /* Boolean test for an already-known global thread id (GDB's homegrown
444 global id, not the system's). */
445 extern int valid_global_thread_id (int global_id);
447 /* Search function to lookup a thread by 'pid'. */
448 extern struct thread_info *find_thread_ptid (ptid_t ptid);
450 /* Find thread by GDB global thread ID. */
451 struct thread_info *find_thread_global_id (int global_id);
453 /* Finds the first thread of the inferior given by PID. If PID is -1,
454 returns the first thread in the list. */
455 struct thread_info *first_thread_of_process (int pid);
457 /* Returns any thread of process PID, giving preference to the current
459 extern struct thread_info *any_thread_of_process (int pid);
461 /* Returns any non-exited thread of process PID, giving preference to
462 the current thread, and to not executing threads. */
463 extern struct thread_info *any_live_thread_of_process (int pid);
465 /* Change the ptid of thread OLD_PTID to NEW_PTID. */
466 void thread_change_ptid (ptid_t old_ptid, ptid_t new_ptid);
468 /* Iterator function to call a user-provided callback function
469 once for each known thread. */
470 typedef int (*thread_callback_func) (struct thread_info *, void *);
471 extern struct thread_info *iterate_over_threads (thread_callback_func, void *);
473 /* Traverse all threads. */
474 #define ALL_THREADS(T) \
475 for (T = thread_list; T; T = T->next) \
477 /* Traverse over all threads, sorted by inferior. */
478 #define ALL_THREADS_BY_INFERIOR(inf, tp) \
479 ALL_INFERIORS (inf) \
483 /* Traverse all threads, except those that have THREAD_EXITED
486 #define ALL_NON_EXITED_THREADS(T) \
487 for (T = thread_list; T; T = T->next) \
488 if ((T)->state != THREAD_EXITED)
490 /* Traverse all threads, including those that have THREAD_EXITED
491 state. Allows deleting the currently iterated thread. */
492 #define ALL_THREADS_SAFE(T, TMP) \
493 for ((T) = thread_list; \
494 (T) != NULL ? ((TMP) = (T)->next, 1): 0; \
497 extern int thread_count (void);
499 /* Switch from one thread to another. Also sets the STOP_PC
501 extern void switch_to_thread (ptid_t ptid);
503 /* Switch from one thread to another. Does not read registers and
504 sets STOP_PC to -1. */
505 extern void switch_to_thread_no_regs (struct thread_info *thread);
507 /* Marks or clears thread(s) PTID as resumed. If PTID is
508 MINUS_ONE_PTID, applies to all threads. If ptid_is_pid(PTID) is
509 true, applies to all threads of the process pointed at by PTID. */
510 extern void set_resumed (ptid_t ptid, int resumed);
512 /* Marks thread PTID is running, or stopped.
513 If PTID is minus_one_ptid, marks all threads. */
514 extern void set_running (ptid_t ptid, int running);
516 /* Marks or clears thread(s) PTID as having been requested to stop.
517 If PTID is MINUS_ONE_PTID, applies to all threads. If
518 ptid_is_pid(PTID) is true, applies to all threads of the process
519 pointed at by PTID. If STOP, then the THREAD_STOP_REQUESTED
520 observer is called with PTID as argument. */
521 extern void set_stop_requested (ptid_t ptid, int stop);
523 /* NOTE: Since the thread state is not a boolean, most times, you do
524 not want to check it with negation. If you really want to check if
525 the thread is stopped,
529 if (is_stopped (ptid))
533 if (!is_running (ptid))
535 The latter also returns true on exited threads, most likelly not
538 /* Reports if in the frontend's perpective, thread PTID is running. */
539 extern int is_running (ptid_t ptid);
541 /* Is this thread listed, but known to have exited? We keep it listed
542 (but not visible) until it's safe to delete. */
543 extern int is_exited (ptid_t ptid);
545 /* In the frontend's perpective, is this thread stopped? */
546 extern int is_stopped (ptid_t ptid);
548 /* Marks thread PTID as executing, or not. If PTID is minus_one_ptid,
551 Note that this is different from the running state. See the
552 description of state and executing fields of struct
554 extern void set_executing (ptid_t ptid, int executing);
556 /* Reports if thread PTID is executing. */
557 extern int is_executing (ptid_t ptid);
559 /* True if any (known or unknown) thread is or may be executing. */
560 extern int threads_are_executing (void);
562 /* Merge the executing property of thread PTID over to its thread
563 state property (frontend running/stopped view).
565 "not executing" -> "stopped"
566 "executing" -> "running"
569 If PTID is minus_one_ptid, go over all threads.
571 Notifications are only emitted if the thread state did change. */
572 extern void finish_thread_state (ptid_t ptid);
574 /* Same as FINISH_THREAD_STATE, but with an interface suitable to be
575 registered as a cleanup. PTID_P points to the ptid_t that is
576 passed to FINISH_THREAD_STATE. */
577 extern void finish_thread_state_cleanup (void *ptid_p);
579 /* Commands with a prefix of `thread'. */
580 extern struct cmd_list_element *thread_cmd_list;
582 extern void thread_command (char *tidstr, int from_tty);
584 /* Print notices on thread events (attach, detach, etc.), set with
585 `set print thread-events'. */
586 extern int print_thread_events;
588 /* Prints the list of threads and their details on UIOUT. If
589 REQUESTED_THREADS, a list of GDB ids/ranges, is not NULL, only
590 print threads whose ID is included in the list. If PID is not -1,
591 only print threads from the process PID. Otherwise, threads from
592 all attached PIDs are printed. If both REQUESTED_THREADS is not
593 NULL and PID is not -1, then the thread is printed if it belongs to
594 the specified process. Otherwise, an error is raised. */
595 extern void print_thread_info (struct ui_out *uiout, char *requested_threads,
598 extern struct cleanup *make_cleanup_restore_current_thread (void);
600 /* Returns a pointer into the thread_info corresponding to
601 INFERIOR_PTID. INFERIOR_PTID *must* be in the thread list. */
602 extern struct thread_info* inferior_thread (void);
604 extern void update_thread_list (void);
606 /* Delete any thread the target says is no longer alive. */
608 extern void prune_threads (void);
610 /* Delete threads marked THREAD_EXITED. Unlike prune_threads, this
611 does not consult the target about whether the thread is alive right
613 extern void delete_exited_threads (void);
615 /* Return true if PC is in the stepping range of THREAD. */
617 int pc_in_thread_step_range (CORE_ADDR pc, struct thread_info *thread);
619 extern struct cleanup *enable_thread_stack_temporaries (ptid_t ptid);
621 extern int thread_stack_temporaries_enabled_p (ptid_t ptid);
623 extern void push_thread_stack_temporary (ptid_t ptid, struct value *v);
625 extern struct value *get_last_thread_stack_temporary (ptid_t);
627 extern int value_in_thread_stack_temporaries (struct value *, ptid_t);
629 /* Add TP to the end of its inferior's pending step-over chain. */
631 extern void thread_step_over_chain_enqueue (struct thread_info *tp);
633 /* Remove TP from its inferior's pending step-over chain. */
635 extern void thread_step_over_chain_remove (struct thread_info *tp);
637 /* Return the next thread in the step-over chain starting at TP. NULL
638 if TP is the last entry in the chain. */
640 extern struct thread_info *thread_step_over_chain_next (struct thread_info *tp);
642 /* Return true if TP is in the step-over chain. */
644 extern int thread_is_in_step_over_chain (struct thread_info *tp);
646 /* Cancel any ongoing execution command. */
648 extern void thread_cancel_execution_command (struct thread_info *thr);
650 /* Check whether it makes sense to access a register of the current
651 thread at this point. If not, throw an error (e.g., the thread is
653 extern void validate_registers_access (void);
655 /* Check whether it makes sense to access a register of PTID at this point.
656 Returns true if registers may be accessed; false otherwise. */
657 extern bool can_access_registers_ptid (ptid_t ptid);
659 /* Returns whether to show which thread hit the breakpoint, received a
660 signal, etc. and ended up causing a user-visible stop. This is
661 true iff we ever detected multiple threads. */
662 extern int show_thread_that_caused_stop (void);
664 /* Print the message for a thread or/and frame selected. */
665 extern void print_selected_thread_frame (struct ui_out *uiout,
666 user_selected_what selection);
668 extern struct thread_info *thread_list;
670 #endif /* GDBTHREAD_H */