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"
34 #include "common/refcounted-object.h"
36 /* Frontend view of the thread state. Possible extensions: stepping,
37 finishing, until(ling),... */
45 /* Inferior thread specific part of `struct infcall_control_state'.
47 Inferior process counterpart is `struct inferior_control_state'. */
49 struct thread_control_state
51 /* User/external stepping state. */
53 /* Step-resume or longjmp-resume breakpoint. */
54 struct breakpoint *step_resume_breakpoint;
56 /* Exception-resume breakpoint. */
57 struct breakpoint *exception_resume_breakpoint;
59 /* Breakpoints used for software single stepping. Plural, because
60 it may have multiple locations. E.g., if stepping over a
61 conditional branch instruction we can't decode the condition for,
62 we'll need to put a breakpoint at the branch destination, and
63 another at the instruction after the branch. */
64 struct breakpoint *single_step_breakpoints;
66 /* Range to single step within.
68 If this is nonzero, respond to a single-step signal by continuing
69 to step if the pc is in this range.
71 If step_range_start and step_range_end are both 1, it means to
72 step for a single instruction (FIXME: it might clean up
73 wait_for_inferior in a minor way if this were changed to the
74 address of the instruction and that address plus one. But maybe
76 CORE_ADDR step_range_start; /* Inclusive */
77 CORE_ADDR step_range_end; /* Exclusive */
79 /* Function the thread was in as of last it started stepping. */
80 struct symbol *step_start_function;
82 /* If GDB issues a target step request, and this is nonzero, the
83 target should single-step this thread once, and then continue
84 single-stepping it without GDB core involvement as long as the
85 thread stops in the step range above. If this is zero, the
86 target should ignore the step range, and only issue one single
90 /* Stack frame address as of when stepping command was issued.
91 This is how we know when we step into a subroutine call, and how
92 to set the frame for the breakpoint used to step out. */
93 struct frame_id step_frame_id;
95 /* Similarly, the frame ID of the underlying stack frame (skipping
96 any inlined frames). */
97 struct frame_id step_stack_frame_id;
99 /* Nonzero if we are presently stepping over a breakpoint.
101 If we hit a breakpoint or watchpoint, and then continue, we need
102 to single step the current thread with breakpoints disabled, to
103 avoid hitting the same breakpoint or watchpoint again. And we
104 should step just a single thread and keep other threads stopped,
105 so that other threads don't miss breakpoints while they are
108 So, this variable simultaneously means that we need to single
109 step the current thread, keep other threads stopped, and that
110 breakpoints should be removed while we step.
112 This variable is set either:
113 - in proceed, when we resume inferior on user's explicit request
114 - in keep_going, if handle_inferior_event decides we need to
115 step over breakpoint.
117 The variable is cleared in normal_stop. The proceed calls
118 wait_for_inferior, which calls handle_inferior_event in a loop,
119 and until wait_for_inferior exits, this variable is changed only
123 /* Nonzero if the thread is being proceeded for a "finish" command
124 or a similar situation when return value should be printed. */
125 int proceed_to_finish;
127 /* Nonzero if the thread is being proceeded for an inferior function
131 enum step_over_calls_kind step_over_calls;
133 /* Nonzero if stopped due to a step command. */
136 /* Chain containing status of breakpoint(s) the thread stopped
140 /* Whether the command that started the thread was a stepping
141 command. This is used to decide whether "set scheduler-locking
142 step" behaves like "on" or "off". */
143 int stepping_command;
146 /* Inferior thread specific part of `struct infcall_suspend_state'. */
148 struct thread_suspend_state
150 /* Last signal that the inferior received (why it stopped). When
151 the thread is resumed, this signal is delivered. Note: the
152 target should not check whether the signal is in pass state,
153 because the signal may have been explicitly passed with the
154 "signal" command, which overrides "handle nopass". If the signal
155 should be suppressed, the core will take care of clearing this
156 before the target is resumed. */
157 enum gdb_signal stop_signal;
159 /* The reason the thread last stopped, if we need to track it
160 (breakpoint, watchpoint, etc.) */
161 enum target_stop_reason stop_reason;
163 /* The waitstatus for this thread's last event. */
164 struct target_waitstatus waitstatus;
165 /* If true WAITSTATUS hasn't been handled yet. */
166 int waitstatus_pending_p;
168 /* Record the pc of the thread the last time it stopped. (This is
169 not the current thread's PC as that may have changed since the
170 last stop, e.g., "return" command, or "p $pc = 0xf000"). This is
171 used in coordination with stop_reason and waitstatus_pending_p:
172 if the thread's PC is changed since it last stopped, a pending
173 breakpoint waitstatus is discarded. */
177 typedef struct value *value_ptr;
178 DEF_VEC_P (value_ptr);
179 typedef VEC (value_ptr) value_vec;
181 /* Threads are intrusively refcounted objects. Being the
182 user-selected thread is normally considered an implicit strong
183 reference and is thus not accounted in the refcount, unlike
184 inferior objects. This is necessary, because there's no "current
185 thread" pointer. Instead the current thread is inferred from the
186 inferior_ptid global. However, when GDB needs to remember the
187 selected thread to later restore it, GDB bumps the thread object's
188 refcount, to prevent something deleting the thread object before
189 reverting back (e.g., due to a "kill" command. If the thread
190 meanwhile exits before being re-selected, then the thread object is
191 left listed in the thread list, but marked with state
192 THREAD_EXITED. (See make_cleanup_restore_current_thread and
193 delete_thread). All other thread references are considered weak
194 references. Placing a thread in the thread list is an implicit
195 strong reference, and is thus not accounted for in the thread's
198 class thread_info : public refcounted_object
201 explicit thread_info (inferior *inf, ptid_t ptid);
204 bool deletable () const
206 /* If this is the current thread, or there's code out there that
207 relies on it existing (refcount > 0) we can't delete yet. */
208 return (refcount () == 0 && !ptid_equal (ptid, inferior_ptid));
211 struct thread_info *next = NULL;
212 ptid_t ptid; /* "Actual process id";
213 In fact, this may be overloaded with
214 kernel thread id, etc. */
216 /* Each thread has two GDB IDs.
218 a) The thread ID (Id). This consists of the pair of:
220 - the number of the thread's inferior and,
222 - the thread's thread number in its inferior, aka, the
223 per-inferior thread number. This number is unique in the
224 inferior but not unique between inferiors.
226 b) The global ID (GId). This is a a single integer unique
227 between all inferiors.
231 (gdb) info threads -gid
232 Id GId Target Id Frame
233 * 1.1 1 Thread A 0x16a09237 in foo () at foo.c:10
234 1.2 3 Thread B 0x15ebc6ed in bar () at foo.c:20
235 1.3 5 Thread C 0x15ebc6ed in bar () at foo.c:20
236 2.1 2 Thread A 0x16a09237 in foo () at foo.c:10
237 2.2 4 Thread B 0x15ebc6ed in bar () at foo.c:20
238 2.3 6 Thread C 0x15ebc6ed in bar () at foo.c:20
240 Above, both inferiors 1 and 2 have threads numbered 1-3, but each
241 thread has its own unique global ID. */
243 /* The thread's global GDB thread number. This is exposed to MI,
244 Python/Scheme, visible with "info threads -gid", and is also what
245 the $_gthread convenience variable is bound to. */
248 /* The per-inferior thread number. This is unique in the inferior
249 the thread belongs to, but not unique between inferiors. This is
250 what the $_thread convenience variable is bound to. */
253 /* The inferior this thread belongs to. */
254 struct inferior *inf;
256 /* The name of the thread, as specified by the user. This is NULL
257 if the thread does not have a user-given name. */
260 /* Non-zero means the thread is executing. Note: this is different
261 from saying that there is an active target and we are stopped at
262 a breakpoint, for instance. This is a real indicator whether the
263 thread is off and running. */
266 /* Non-zero if this thread is resumed from infrun's perspective.
267 Note that a thread can be marked both as not-executing and
268 resumed at the same time. This happens if we try to resume a
269 thread that has a wait status pending. We shouldn't let the
270 thread really run until that wait status has been processed, but
271 we should not process that wait status if we didn't try to let
275 /* Frontend view of the thread state. Note that the THREAD_RUNNING/
276 THREAD_STOPPED states are different from EXECUTING. When the
277 thread is stopped internally while handling an internal event,
278 like a software single-step breakpoint, EXECUTING will be false,
279 but STATE will still be THREAD_RUNNING. */
280 enum thread_state state = THREAD_STOPPED;
282 /* State of GDB control of inferior thread execution.
283 See `struct thread_control_state'. */
284 thread_control_state control {};
286 /* State of inferior thread to restore after GDB is done with an inferior
287 call. See `struct thread_suspend_state'. */
288 thread_suspend_state suspend {};
290 int current_line = 0;
291 struct symtab *current_symtab = NULL;
293 /* Internal stepping state. */
295 /* Record the pc of the thread the last time it was resumed. (It
296 can't be done on stop as the PC may change since the last stop,
297 e.g., "return" command, or "p $pc = 0xf000"). This is maintained
298 by proceed and keep_going, and among other things, it's used in
299 adjust_pc_after_break to distinguish a hardware single-step
300 SIGTRAP from a breakpoint SIGTRAP. */
301 CORE_ADDR prev_pc = 0;
303 /* Did we set the thread stepping a breakpoint instruction? This is
304 used in conjunction with PREV_PC to decide whether to adjust the
306 int stepped_breakpoint = 0;
308 /* Should we step over breakpoint next time keep_going is called? */
309 int stepping_over_breakpoint = 0;
311 /* Should we step over a watchpoint next time keep_going is called?
312 This is needed on targets with non-continuable, non-steppable
314 int stepping_over_watchpoint = 0;
316 /* Set to TRUE if we should finish single-stepping over a breakpoint
317 after hitting the current step-resume breakpoint. The context here
318 is that GDB is to do `next' or `step' while signal arrives.
319 When stepping over a breakpoint and signal arrives, GDB will attempt
320 to skip signal handler, so it inserts a step_resume_breakpoint at the
321 signal return address, and resume inferior.
322 step_after_step_resume_breakpoint is set to TRUE at this moment in
323 order to keep GDB in mind that there is still a breakpoint to step over
324 when GDB gets back SIGTRAP from step_resume_breakpoint. */
325 int step_after_step_resume_breakpoint = 0;
327 /* Pointer to the state machine manager object that handles what is
328 left to do for the thread's execution command after the target
329 stops. Several execution commands use it. */
330 struct thread_fsm *thread_fsm = NULL;
332 /* This is used to remember when a fork or vfork event was caught by
333 a catchpoint, and thus the event is to be followed at the next
334 resume of the thread, and not immediately. */
335 struct target_waitstatus pending_follow;
337 /* True if this thread has been explicitly requested to stop. */
338 int stop_requested = 0;
340 /* The initiating frame of a nexting operation, used for deciding
341 which exceptions to intercept. If it is null_frame_id no
342 bp_longjmp or bp_exception but longjmp has been caught just for
343 bp_longjmp_call_dummy. */
344 struct frame_id initiating_frame = null_frame_id;
346 /* Private data used by the target vector implementation. */
347 struct private_thread_info *priv = NULL;
349 /* Function that is called to free PRIVATE. If this is NULL, then
350 xfree will be called on PRIVATE. */
351 void (*private_dtor) (struct private_thread_info *) = NULL;
353 /* Branch trace information for this thread. */
354 struct btrace_thread_info btrace {};
356 /* Flag which indicates that the stack temporaries should be stored while
357 evaluating expressions. */
358 int stack_temporaries_enabled = 0;
360 /* Values that are stored as temporaries on stack while evaluating
362 value_vec *stack_temporaries = NULL;
364 /* Step-over chain. A thread is in the step-over queue if these are
365 non-NULL. If only a single thread is in the chain, then these
366 fields point to self. */
367 struct thread_info *step_over_prev = NULL;
368 struct thread_info *step_over_next = NULL;
371 /* Create an empty thread list, or empty the existing one. */
372 extern void init_thread_list (void);
374 /* Add a thread to the thread list, print a message
375 that a new thread is found, and return the pointer to
376 the new thread. Caller my use this pointer to
377 initialize the private thread data. */
378 extern struct thread_info *add_thread (ptid_t ptid);
380 /* Same as add_thread, but does not print a message
382 extern struct thread_info *add_thread_silent (ptid_t ptid);
384 /* Same as add_thread, and sets the private info. */
385 extern struct thread_info *add_thread_with_info (ptid_t ptid,
386 struct private_thread_info *);
388 /* Delete an existing thread list entry. */
389 extern void delete_thread (ptid_t);
391 /* Delete an existing thread list entry, and be quiet about it. Used
392 after the process this thread having belonged to having already
393 exited, for example. */
394 extern void delete_thread_silent (ptid_t);
396 /* Delete a step_resume_breakpoint from the thread database. */
397 extern void delete_step_resume_breakpoint (struct thread_info *);
399 /* Delete an exception_resume_breakpoint from the thread database. */
400 extern void delete_exception_resume_breakpoint (struct thread_info *);
402 /* Delete the single-step breakpoints of thread TP, if any. */
403 extern void delete_single_step_breakpoints (struct thread_info *tp);
405 /* Check if the thread has software single stepping breakpoints
407 extern int thread_has_single_step_breakpoints_set (struct thread_info *tp);
409 /* Check whether the thread has software single stepping breakpoints
411 extern int thread_has_single_step_breakpoint_here (struct thread_info *tp,
412 struct address_space *aspace,
415 /* Translate the global integer thread id (GDB's homegrown id, not the
416 system's) into a "pid" (which may be overloaded with extra thread
418 extern ptid_t global_thread_id_to_ptid (int num);
420 /* Translate a 'pid' (which may be overloaded with extra thread
421 information) into the global integer thread id (GDB's homegrown id,
422 not the system's). */
423 extern int ptid_to_global_thread_id (ptid_t ptid);
425 /* Returns whether to show inferior-qualified thread IDs, or plain
426 thread numbers. Inferior-qualified IDs are shown whenever we have
427 multiple inferiors, or the only inferior left has number > 1. */
428 extern int show_inferior_qualified_tids (void);
430 /* Return a string version of THR's thread ID. If there are multiple
431 inferiors, then this prints the inferior-qualifier form, otherwise
432 it only prints the thread number. The result is stored in a
433 circular static buffer, NUMCELLS deep. */
434 const char *print_thread_id (struct thread_info *thr);
436 /* Boolean test for an already-known pid (which may be overloaded with
437 extra thread information). */
438 extern int in_thread_list (ptid_t ptid);
440 /* Boolean test for an already-known global thread id (GDB's homegrown
441 global id, not the system's). */
442 extern int valid_global_thread_id (int global_id);
444 /* Search function to lookup a thread by 'pid'. */
445 extern struct thread_info *find_thread_ptid (ptid_t ptid);
447 /* Find thread by GDB global thread ID. */
448 struct thread_info *find_thread_global_id (int global_id);
450 /* Finds the first thread of the inferior given by PID. If PID is -1,
451 returns the first thread in the list. */
452 struct thread_info *first_thread_of_process (int pid);
454 /* Returns any thread of process PID, giving preference to the current
456 extern struct thread_info *any_thread_of_process (int pid);
458 /* Returns any non-exited thread of process PID, giving preference to
459 the current thread, and to not executing threads. */
460 extern struct thread_info *any_live_thread_of_process (int pid);
462 /* Change the ptid of thread OLD_PTID to NEW_PTID. */
463 void thread_change_ptid (ptid_t old_ptid, ptid_t new_ptid);
465 /* Iterator function to call a user-provided callback function
466 once for each known thread. */
467 typedef int (*thread_callback_func) (struct thread_info *, void *);
468 extern struct thread_info *iterate_over_threads (thread_callback_func, void *);
470 /* Traverse all threads. */
471 #define ALL_THREADS(T) \
472 for (T = thread_list; T; T = T->next) \
474 /* Traverse over all threads, sorted by inferior. */
475 #define ALL_THREADS_BY_INFERIOR(inf, tp) \
476 ALL_INFERIORS (inf) \
480 /* Traverse all threads, except those that have THREAD_EXITED
483 #define ALL_NON_EXITED_THREADS(T) \
484 for (T = thread_list; T; T = T->next) \
485 if ((T)->state != THREAD_EXITED)
487 /* Traverse all threads, including those that have THREAD_EXITED
488 state. Allows deleting the currently iterated thread. */
489 #define ALL_THREADS_SAFE(T, TMP) \
490 for ((T) = thread_list; \
491 (T) != NULL ? ((TMP) = (T)->next, 1): 0; \
494 extern int thread_count (void);
496 /* Switch from one thread to another. Also sets the STOP_PC
498 extern void switch_to_thread (ptid_t ptid);
500 /* Switch from one thread to another. Does not read registers and
501 sets STOP_PC to -1. */
502 extern void switch_to_thread_no_regs (struct thread_info *thread);
504 /* Marks or clears thread(s) PTID as resumed. If PTID is
505 MINUS_ONE_PTID, applies to all threads. If ptid_is_pid(PTID) is
506 true, applies to all threads of the process pointed at by PTID. */
507 extern void set_resumed (ptid_t ptid, int resumed);
509 /* Marks thread PTID is running, or stopped.
510 If PTID is minus_one_ptid, marks all threads. */
511 extern void set_running (ptid_t ptid, int running);
513 /* Marks or clears thread(s) PTID as having been requested to stop.
514 If PTID is MINUS_ONE_PTID, applies to all threads. If
515 ptid_is_pid(PTID) is true, applies to all threads of the process
516 pointed at by PTID. If STOP, then the THREAD_STOP_REQUESTED
517 observer is called with PTID as argument. */
518 extern void set_stop_requested (ptid_t ptid, int stop);
520 /* NOTE: Since the thread state is not a boolean, most times, you do
521 not want to check it with negation. If you really want to check if
522 the thread is stopped,
526 if (is_stopped (ptid))
530 if (!is_running (ptid))
532 The latter also returns true on exited threads, most likelly not
535 /* Reports if in the frontend's perpective, thread PTID is running. */
536 extern int is_running (ptid_t ptid);
538 /* Is this thread listed, but known to have exited? We keep it listed
539 (but not visible) until it's safe to delete. */
540 extern int is_exited (ptid_t ptid);
542 /* In the frontend's perpective, is this thread stopped? */
543 extern int is_stopped (ptid_t ptid);
545 /* Marks thread PTID as executing, or not. If PTID is minus_one_ptid,
548 Note that this is different from the running state. See the
549 description of state and executing fields of struct
551 extern void set_executing (ptid_t ptid, int executing);
553 /* Reports if thread PTID is executing. */
554 extern int is_executing (ptid_t ptid);
556 /* True if any (known or unknown) thread is or may be executing. */
557 extern int threads_are_executing (void);
559 /* Merge the executing property of thread PTID over to its thread
560 state property (frontend running/stopped view).
562 "not executing" -> "stopped"
563 "executing" -> "running"
566 If PTID is minus_one_ptid, go over all threads.
568 Notifications are only emitted if the thread state did change. */
569 extern void finish_thread_state (ptid_t ptid);
571 /* Same as FINISH_THREAD_STATE, but with an interface suitable to be
572 registered as a cleanup. PTID_P points to the ptid_t that is
573 passed to FINISH_THREAD_STATE. */
574 extern void finish_thread_state_cleanup (void *ptid_p);
576 /* Commands with a prefix of `thread'. */
577 extern struct cmd_list_element *thread_cmd_list;
579 extern void thread_command (char *tidstr, int from_tty);
581 /* Print notices on thread events (attach, detach, etc.), set with
582 `set print thread-events'. */
583 extern int print_thread_events;
585 /* Prints the list of threads and their details on UIOUT. If
586 REQUESTED_THREADS, a list of GDB ids/ranges, is not NULL, only
587 print threads whose ID is included in the list. If PID is not -1,
588 only print threads from the process PID. Otherwise, threads from
589 all attached PIDs are printed. If both REQUESTED_THREADS is not
590 NULL and PID is not -1, then the thread is printed if it belongs to
591 the specified process. Otherwise, an error is raised. */
592 extern void print_thread_info (struct ui_out *uiout, char *requested_threads,
595 extern struct cleanup *make_cleanup_restore_current_thread (void);
597 /* Returns a pointer into the thread_info corresponding to
598 INFERIOR_PTID. INFERIOR_PTID *must* be in the thread list. */
599 extern struct thread_info* inferior_thread (void);
601 extern void update_thread_list (void);
603 /* Delete any thread the target says is no longer alive. */
605 extern void prune_threads (void);
607 /* Delete threads marked THREAD_EXITED. Unlike prune_threads, this
608 does not consult the target about whether the thread is alive right
610 extern void delete_exited_threads (void);
612 /* Return true if PC is in the stepping range of THREAD. */
614 int pc_in_thread_step_range (CORE_ADDR pc, struct thread_info *thread);
616 extern struct cleanup *enable_thread_stack_temporaries (ptid_t ptid);
618 extern int thread_stack_temporaries_enabled_p (ptid_t ptid);
620 extern void push_thread_stack_temporary (ptid_t ptid, struct value *v);
622 extern struct value *get_last_thread_stack_temporary (ptid_t);
624 extern int value_in_thread_stack_temporaries (struct value *, ptid_t);
626 /* Add TP to the end of its inferior's pending step-over chain. */
628 extern void thread_step_over_chain_enqueue (struct thread_info *tp);
630 /* Remove TP from its inferior's pending step-over chain. */
632 extern void thread_step_over_chain_remove (struct thread_info *tp);
634 /* Return the next thread in the step-over chain starting at TP. NULL
635 if TP is the last entry in the chain. */
637 extern struct thread_info *thread_step_over_chain_next (struct thread_info *tp);
639 /* Return true if TP is in the step-over chain. */
641 extern int thread_is_in_step_over_chain (struct thread_info *tp);
643 /* Cancel any ongoing execution command. */
645 extern void thread_cancel_execution_command (struct thread_info *thr);
647 /* Check whether it makes sense to access a register of the current
648 thread at this point. If not, throw an error (e.g., the thread is
650 extern void validate_registers_access (void);
652 /* Check whether it makes sense to access a register of PTID at this point.
653 Returns true if registers may be accessed; false otherwise. */
654 extern bool can_access_registers_ptid (ptid_t ptid);
656 /* Returns whether to show which thread hit the breakpoint, received a
657 signal, etc. and ended up causing a user-visible stop. This is
658 true iff we ever detected multiple threads. */
659 extern int show_thread_that_caused_stop (void);
661 /* Print the message for a thread or/and frame selected. */
662 extern void print_selected_thread_frame (struct ui_out *uiout,
663 user_selected_what selection);
665 extern struct thread_info *thread_list;
667 #endif /* GDBTHREAD_H */