/* Multi-process/thread control defs for GDB, the GNU debugger.
- Copyright (C) 1987-2015 Free Software Foundation, Inc.
+ Copyright (C) 1987-2017 Free Software Foundation, Inc.
Contributed by Lynx Real-Time Systems, Inc. Los Gatos, CA.
#include "inferior.h"
#include "btrace.h"
#include "common/vec.h"
+#include "target/waitstatus.h"
+#include "cli/cli-utils.h"
+#include "common/refcounted-object.h"
+#include "common-gdbthread.h"
/* Frontend view of the thread state. Possible extensions: stepping,
finishing, until(ling),... */
at. */
bpstat stop_bpstat;
- /* The interpreter that issued the execution command. NULL if the
- thread was resumed as a result of a command applied to some other
- thread (e.g., "next" with scheduler-locking off). */
- struct interp *command_interp;
-
/* Whether the command that started the thread was a stepping
command. This is used to decide whether "set scheduler-locking
step" behaves like "on" or "off". */
int stepping_command;
};
-/* Inferior thread specific part of `struct infcall_suspend_state'.
-
- Inferior process counterpart is `struct inferior_suspend_state'. */
+/* Inferior thread specific part of `struct infcall_suspend_state'. */
struct thread_suspend_state
{
should be suppressed, the core will take care of clearing this
before the target is resumed. */
enum gdb_signal stop_signal;
+
+ /* The reason the thread last stopped, if we need to track it
+ (breakpoint, watchpoint, etc.) */
+ enum target_stop_reason stop_reason;
+
+ /* The waitstatus for this thread's last event. */
+ struct target_waitstatus waitstatus;
+ /* If true WAITSTATUS hasn't been handled yet. */
+ int waitstatus_pending_p;
+
+ /* Record the pc of the thread the last time it stopped. (This is
+ not the current thread's PC as that may have changed since the
+ last stop, e.g., "return" command, or "p $pc = 0xf000"). This is
+ used in coordination with stop_reason and waitstatus_pending_p:
+ if the thread's PC is changed since it last stopped, a pending
+ breakpoint waitstatus is discarded. */
+ CORE_ADDR stop_pc;
};
typedef struct value *value_ptr;
DEF_VEC_P (value_ptr);
typedef VEC (value_ptr) value_vec;
-struct thread_info
+/* Threads are intrusively refcounted objects. Being the
+ user-selected thread is normally considered an implicit strong
+ reference and is thus not accounted in the refcount, unlike
+ inferior objects. This is necessary, because there's no "current
+ thread" pointer. Instead the current thread is inferred from the
+ inferior_ptid global. However, when GDB needs to remember the
+ selected thread to later restore it, GDB bumps the thread object's
+ refcount, to prevent something deleting the thread object before
+ reverting back (e.g., due to a "kill" command). If the thread
+ meanwhile exits before being re-selected, then the thread object is
+ left listed in the thread list, but marked with state
+ THREAD_EXITED. (See make_cleanup_restore_current_thread and
+ delete_thread). All other thread references are considered weak
+ references. Placing a thread in the thread list is an implicit
+ strong reference, and is thus not accounted for in the thread's
+ refcount. */
+
+class thread_info : public refcounted_object
{
- struct thread_info *next;
+public:
+ explicit thread_info (inferior *inf, ptid_t ptid);
+ ~thread_info ();
+
+ bool deletable () const
+ {
+ /* If this is the current thread, or there's code out there that
+ relies on it existing (refcount > 0) we can't delete yet. */
+ return (refcount () == 0 && !ptid_equal (ptid, inferior_ptid));
+ }
+
+ struct thread_info *next = NULL;
ptid_t ptid; /* "Actual process id";
In fact, this may be overloaded with
kernel thread id, etc. */
- int num; /* Convenient handle (GDB thread id) */
+
+ /* Each thread has two GDB IDs.
+
+ a) The thread ID (Id). This consists of the pair of:
+
+ - the number of the thread's inferior and,
+
+ - the thread's thread number in its inferior, aka, the
+ per-inferior thread number. This number is unique in the
+ inferior but not unique between inferiors.
+
+ b) The global ID (GId). This is a a single integer unique
+ between all inferiors.
+
+ E.g.:
+
+ (gdb) info threads -gid
+ Id GId Target Id Frame
+ * 1.1 1 Thread A 0x16a09237 in foo () at foo.c:10
+ 1.2 3 Thread B 0x15ebc6ed in bar () at foo.c:20
+ 1.3 5 Thread C 0x15ebc6ed in bar () at foo.c:20
+ 2.1 2 Thread A 0x16a09237 in foo () at foo.c:10
+ 2.2 4 Thread B 0x15ebc6ed in bar () at foo.c:20
+ 2.3 6 Thread C 0x15ebc6ed in bar () at foo.c:20
+
+ Above, both inferiors 1 and 2 have threads numbered 1-3, but each
+ thread has its own unique global ID. */
+
+ /* The thread's global GDB thread number. This is exposed to MI,
+ Python/Scheme, visible with "info threads -gid", and is also what
+ the $_gthread convenience variable is bound to. */
+ int global_num;
+
+ /* The per-inferior thread number. This is unique in the inferior
+ the thread belongs to, but not unique between inferiors. This is
+ what the $_thread convenience variable is bound to. */
+ int per_inf_num;
+
+ /* The inferior this thread belongs to. */
+ struct inferior *inf;
/* The name of the thread, as specified by the user. This is NULL
if the thread does not have a user-given name. */
- char *name;
+ char *name = NULL;
/* Non-zero means the thread is executing. Note: this is different
from saying that there is an active target and we are stopped at
a breakpoint, for instance. This is a real indicator whether the
thread is off and running. */
- int executing;
+ int executing = 0;
+
+ /* Non-zero if this thread is resumed from infrun's perspective.
+ Note that a thread can be marked both as not-executing and
+ resumed at the same time. This happens if we try to resume a
+ thread that has a wait status pending. We shouldn't let the
+ thread really run until that wait status has been processed, but
+ we should not process that wait status if we didn't try to let
+ the thread run. */
+ int resumed = 0;
/* Frontend view of the thread state. Note that the THREAD_RUNNING/
THREAD_STOPPED states are different from EXECUTING. When the
thread is stopped internally while handling an internal event,
like a software single-step breakpoint, EXECUTING will be false,
but STATE will still be THREAD_RUNNING. */
- enum thread_state state;
-
- /* If this is > 0, then it means there's code out there that relies
- on this thread being listed. Don't delete it from the lists even
- if we detect it exiting. */
- int refcount;
+ enum thread_state state = THREAD_STOPPED;
/* State of GDB control of inferior thread execution.
See `struct thread_control_state'. */
- struct thread_control_state control;
+ thread_control_state control {};
/* State of inferior thread to restore after GDB is done with an inferior
call. See `struct thread_suspend_state'. */
- struct thread_suspend_state suspend;
+ thread_suspend_state suspend {};
- int current_line;
- struct symtab *current_symtab;
+ int current_line = 0;
+ struct symtab *current_symtab = NULL;
/* Internal stepping state. */
- /* Record the pc of the thread the last time it stopped. This is
- maintained by proceed and keep_going, and used in
+ /* Record the pc of the thread the last time it was resumed. (It
+ can't be done on stop as the PC may change since the last stop,
+ e.g., "return" command, or "p $pc = 0xf000"). This is maintained
+ by proceed and keep_going, and among other things, it's used in
adjust_pc_after_break to distinguish a hardware single-step
SIGTRAP from a breakpoint SIGTRAP. */
- CORE_ADDR prev_pc;
+ CORE_ADDR prev_pc = 0;
/* Did we set the thread stepping a breakpoint instruction? This is
used in conjunction with PREV_PC to decide whether to adjust the
PC. */
- int stepped_breakpoint;
+ int stepped_breakpoint = 0;
/* Should we step over breakpoint next time keep_going is called? */
- int stepping_over_breakpoint;
+ int stepping_over_breakpoint = 0;
/* Should we step over a watchpoint next time keep_going is called?
This is needed on targets with non-continuable, non-steppable
watchpoints. */
- int stepping_over_watchpoint;
+ int stepping_over_watchpoint = 0;
/* Set to TRUE if we should finish single-stepping over a breakpoint
after hitting the current step-resume breakpoint. The context here
step_after_step_resume_breakpoint is set to TRUE at this moment in
order to keep GDB in mind that there is still a breakpoint to step over
when GDB gets back SIGTRAP from step_resume_breakpoint. */
- int step_after_step_resume_breakpoint;
-
- /* Per-thread command support. */
-
- /* Pointer to what is left to do for an execution command after the
- target stops. Used only in asynchronous mode, by targets that
- support async execution. Several execution commands use it. */
- struct continuation *continuations;
+ int step_after_step_resume_breakpoint = 0;
- /* Similar to the above, but used when a single execution command
- requires several resume/stop iterations. Used by the step
- command. */
- struct continuation *intermediate_continuations;
-
- /* If stepping, nonzero means step count is > 1 so don't print frame
- next time inferior stops if it stops due to stepping. */
- int step_multi;
+ /* Pointer to the state machine manager object that handles what is
+ left to do for the thread's execution command after the target
+ stops. Several execution commands use it. */
+ struct thread_fsm *thread_fsm = NULL;
/* This is used to remember when a fork or vfork event was caught by
a catchpoint, and thus the event is to be followed at the next
struct target_waitstatus pending_follow;
/* True if this thread has been explicitly requested to stop. */
- int stop_requested;
+ int stop_requested = 0;
/* The initiating frame of a nexting operation, used for deciding
which exceptions to intercept. If it is null_frame_id no
bp_longjmp or bp_exception but longjmp has been caught just for
bp_longjmp_call_dummy. */
- struct frame_id initiating_frame;
+ struct frame_id initiating_frame = null_frame_id;
/* Private data used by the target vector implementation. */
- struct private_thread_info *priv;
+ struct private_thread_info *priv = NULL;
/* Function that is called to free PRIVATE. If this is NULL, then
xfree will be called on PRIVATE. */
- void (*private_dtor) (struct private_thread_info *);
+ void (*private_dtor) (struct private_thread_info *) = NULL;
/* Branch trace information for this thread. */
- struct btrace_thread_info btrace;
+ struct btrace_thread_info btrace {};
/* Flag which indicates that the stack temporaries should be stored while
evaluating expressions. */
- int stack_temporaries_enabled;
+ int stack_temporaries_enabled = 0;
/* Values that are stored as temporaries on stack while evaluating
expressions. */
- value_vec *stack_temporaries;
+ value_vec *stack_temporaries = NULL;
+
+ /* Step-over chain. A thread is in the step-over queue if these are
+ non-NULL. If only a single thread is in the chain, then these
+ fields point to self. */
+ struct thread_info *step_over_prev = NULL;
+ struct thread_info *step_over_next = NULL;
};
/* Create an empty thread list, or empty the existing one. */
/* Check whether the thread has software single stepping breakpoints
set at PC. */
extern int thread_has_single_step_breakpoint_here (struct thread_info *tp,
- struct address_space *aspace,
+ const address_space *aspace,
CORE_ADDR addr);
-/* Translate the integer thread id (GDB's homegrown id, not the system's)
- into a "pid" (which may be overloaded with extra thread information). */
-extern ptid_t thread_id_to_pid (int);
+/* Translate the global integer thread id (GDB's homegrown id, not the
+ system's) into a "pid" (which may be overloaded with extra thread
+ information). */
+extern ptid_t global_thread_id_to_ptid (int num);
+
+/* Translate a 'pid' (which may be overloaded with extra thread
+ information) into the global integer thread id (GDB's homegrown id,
+ not the system's). */
+extern int ptid_to_global_thread_id (ptid_t ptid);
+
+/* Returns whether to show inferior-qualified thread IDs, or plain
+ thread numbers. Inferior-qualified IDs are shown whenever we have
+ multiple inferiors, or the only inferior left has number > 1. */
+extern int show_inferior_qualified_tids (void);
-/* Translate a 'pid' (which may be overloaded with extra thread information)
- into the integer thread id (GDB's homegrown id, not the system's). */
-extern int pid_to_thread_id (ptid_t ptid);
+/* Return a string version of THR's thread ID. If there are multiple
+ inferiors, then this prints the inferior-qualifier form, otherwise
+ it only prints the thread number. The result is stored in a
+ circular static buffer, NUMCELLS deep. */
+const char *print_thread_id (struct thread_info *thr);
/* Boolean test for an already-known pid (which may be overloaded with
extra thread information). */
extern int in_thread_list (ptid_t ptid);
-/* Boolean test for an already-known thread id (GDB's homegrown id,
- not the system's). */
-extern int valid_thread_id (int thread);
+/* Boolean test for an already-known global thread id (GDB's homegrown
+ global id, not the system's). */
+extern int valid_global_thread_id (int global_id);
/* Search function to lookup a thread by 'pid'. */
extern struct thread_info *find_thread_ptid (ptid_t ptid);
-/* Find thread by GDB user-visible thread number. */
-struct thread_info *find_thread_id (int num);
+/* Find thread by GDB global thread ID. */
+struct thread_info *find_thread_global_id (int global_id);
+
+/* Find thread by thread library specific handle in inferior INF. */
+struct thread_info *find_thread_by_handle (struct value *thread_handle,
+ struct inferior *inf);
/* Finds the first thread of the inferior given by PID. If PID is -1,
returns the first thread in the list. */
typedef int (*thread_callback_func) (struct thread_info *, void *);
extern struct thread_info *iterate_over_threads (thread_callback_func, void *);
+/* Traverse all threads. */
+#define ALL_THREADS(T) \
+ for (T = thread_list; T; T = T->next) \
+
+/* Traverse over all threads, sorted by inferior. */
+#define ALL_THREADS_BY_INFERIOR(inf, tp) \
+ ALL_INFERIORS (inf) \
+ ALL_THREADS (tp) \
+ if (inf == tp->inf)
+
/* Traverse all threads, except those that have THREAD_EXITED
state. */
extern int thread_count (void);
-/* Switch from one thread to another. */
-extern void switch_to_thread (ptid_t ptid);
+/* Switch from one thread to another. Does not read registers and
+ sets STOP_PC to -1. */
+extern void switch_to_thread_no_regs (struct thread_info *thread);
+
+/* Marks or clears thread(s) PTID as resumed. If PTID is
+ MINUS_ONE_PTID, applies to all threads. If ptid_is_pid(PTID) is
+ true, applies to all threads of the process pointed at by PTID. */
+extern void set_resumed (ptid_t ptid, int resumed);
/* Marks thread PTID is running, or stopped.
If PTID is minus_one_ptid, marks all threads. */
/* Commands with a prefix of `thread'. */
extern struct cmd_list_element *thread_cmd_list;
-extern void thread_command (char *tidstr, int from_tty);
+extern void thread_command (const char *tidstr, int from_tty);
/* Print notices on thread events (attach, detach, etc.), set with
`set print thread-events'. */
extern int print_thread_events;
-extern void print_thread_info (struct ui_out *uiout, char *threads,
+/* Prints the list of threads and their details on UIOUT. If
+ REQUESTED_THREADS, a list of GDB ids/ranges, is not NULL, only
+ print threads whose ID is included in the list. If PID is not -1,
+ only print threads from the process PID. Otherwise, threads from
+ all attached PIDs are printed. If both REQUESTED_THREADS is not
+ NULL and PID is not -1, then the thread is printed if it belongs to
+ the specified process. Otherwise, an error is raised. */
+extern void print_thread_info (struct ui_out *uiout, char *requested_threads,
int pid);
-extern struct cleanup *make_cleanup_restore_current_thread (void);
+/* Save/restore current inferior/thread/frame. */
+
+class scoped_restore_current_thread
+{
+public:
+ scoped_restore_current_thread ();
+ ~scoped_restore_current_thread ();
+
+ DISABLE_COPY_AND_ASSIGN (scoped_restore_current_thread);
+
+private:
+ thread_info *m_thread;
+ inferior *m_inf;
+ frame_id m_selected_frame_id;
+ int m_selected_frame_level;
+ bool m_was_stopped;
+};
/* Returns a pointer into the thread_info corresponding to
INFERIOR_PTID. INFERIOR_PTID *must* be in the thread list. */
extern int value_in_thread_stack_temporaries (struct value *, ptid_t);
+/* Add TP to the end of its inferior's pending step-over chain. */
+
+extern void thread_step_over_chain_enqueue (struct thread_info *tp);
+
+/* Remove TP from its inferior's pending step-over chain. */
+
+extern void thread_step_over_chain_remove (struct thread_info *tp);
+
+/* Return the next thread in the step-over chain starting at TP. NULL
+ if TP is the last entry in the chain. */
+
+extern struct thread_info *thread_step_over_chain_next (struct thread_info *tp);
+
+/* Return true if TP is in the step-over chain. */
+
+extern int thread_is_in_step_over_chain (struct thread_info *tp);
+
+/* Cancel any ongoing execution command. */
+
+extern void thread_cancel_execution_command (struct thread_info *thr);
+
+/* Check whether it makes sense to access a register of the current
+ thread at this point. If not, throw an error (e.g., the thread is
+ executing). */
+extern void validate_registers_access (void);
+
+/* Check whether it makes sense to access a register of PTID at this point.
+ Returns true if registers may be accessed; false otherwise. */
+extern bool can_access_registers_ptid (ptid_t ptid);
+
+/* Returns whether to show which thread hit the breakpoint, received a
+ signal, etc. and ended up causing a user-visible stop. This is
+ true iff we ever detected multiple threads. */
+extern int show_thread_that_caused_stop (void);
+
+/* Print the message for a thread or/and frame selected. */
+extern void print_selected_thread_frame (struct ui_out *uiout,
+ user_selected_what selection);
+
+/* Helper for the CLI's "thread" command and for MI's -thread-select.
+ Selects thread THR. TIDSTR is the original string the thread ID
+ was parsed from. This is used in the error message if THR is not
+ alive anymore. */
+extern void thread_select (const char *tidstr, thread_info *thr);
+
extern struct thread_info *thread_list;
#endif /* GDBTHREAD_H */