1 /* Ada Ravenscar thread support.
3 Copyright (C) 2004-2020 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
22 #include "gdbthread.h"
27 #include "ravenscar-thread.h"
28 #include "observable.h"
34 /* This module provides support for "Ravenscar" tasks (Ada) when
35 debugging on bare-metal targets.
37 The typical situation is when debugging a bare-metal target over
38 the remote protocol. In that situation, the system does not know
39 about high-level concepts such as threads, only about some code
40 running on one or more CPUs. And since the remote protocol does not
41 provide any handling for CPUs, the de facto standard for handling
42 them is to have one thread per CPU, where the thread's ptid has
43 its lwp field set to the CPU number (eg: 1 for the first CPU,
44 2 for the second one, etc). This module will make that assumption.
46 This module then creates and maintains the list of threads based
47 on the list of Ada tasks, with one thread per Ada task. The convention
48 is that threads corresponding to the CPUs (see assumption above)
49 have a ptid_t of the form (PID, LWP, 0), while threads corresponding
50 to our Ada tasks have a ptid_t of the form (PID, 0, TID) where TID
51 is the Ada task's ID as extracted from Ada runtime information.
53 Switching to a given Ada task (or its underlying thread) is performed
54 by fetching the registers of that task from the memory area where
55 the registers were saved. For any of the other operations, the
56 operation is performed by first finding the CPU on which the task
57 is running, switching to its corresponding ptid, and then performing
58 the operation on that ptid using the target beneath us. */
60 /* If true, ravenscar task support is enabled. */
61 static bool ravenscar_task_support
= true;
63 static const char running_thread_name
[] = "__gnat_running_thread_table";
65 static const char known_tasks_name
[] = "system__tasking__debug__known_tasks";
66 static const char first_task_name
[] = "system__tasking__debug__first_task";
68 static const char ravenscar_runtime_initializer
[]
69 = "system__bb__threads__initialize";
71 static const target_info ravenscar_target_info
= {
73 N_("Ravenscar tasks."),
74 N_("Ravenscar tasks support.")
77 struct ravenscar_thread_target final
: public target_ops
79 ravenscar_thread_target ()
81 update_inferior_ptid ();
84 const target_info
&info () const override
85 { return ravenscar_target_info
; }
87 strata
stratum () const override
{ return thread_stratum
; }
89 ptid_t
wait (ptid_t
, struct target_waitstatus
*, int) override
;
90 void resume (ptid_t
, int, enum gdb_signal
) override
;
92 void fetch_registers (struct regcache
*, int) override
;
93 void store_registers (struct regcache
*, int) override
;
95 void prepare_to_store (struct regcache
*) override
;
97 bool stopped_by_sw_breakpoint () override
;
99 bool stopped_by_hw_breakpoint () override
;
101 bool stopped_by_watchpoint () override
;
103 bool stopped_data_address (CORE_ADDR
*) override
;
105 bool thread_alive (ptid_t ptid
) override
;
107 int core_of_thread (ptid_t ptid
) override
;
109 void update_thread_list () override
;
111 const char *extra_thread_info (struct thread_info
*) override
;
113 std::string
pid_to_str (ptid_t
) override
;
115 ptid_t
get_ada_task_ptid (long lwp
, long thread
) override
;
117 void mourn_inferior () override
;
119 void close () override
126 /* PTID of the last thread that received an event.
127 This can be useful to determine the associated task that received
128 the event, to make it the current task. */
129 ptid_t m_base_ptid
= null_ptid
;
131 void update_inferior_ptid ();
132 ptid_t
active_task (int cpu
);
133 bool task_is_currently_active (ptid_t ptid
);
134 bool runtime_initialized ();
137 /* Return true iff PTID corresponds to a ravenscar task. */
140 is_ravenscar_task (ptid_t ptid
)
142 /* By construction, ravenscar tasks have their LWP set to zero.
143 Also make sure that the TID is nonzero, as some remotes, when
144 asked for the list of threads, will return the first thread
145 as having its TID set to zero. For instance, TSIM version
146 2.0.48 for LEON3 sends 'm0' as a reply to the 'qfThreadInfo'
147 query, which the remote protocol layer then treats as a thread
148 whose TID is 0. This is obviously not a ravenscar task. */
149 return ptid
.lwp () == 0 && ptid
.tid () != 0;
152 /* Given PTID, which can be either a ravenscar task or a CPU thread,
153 return which CPU that ptid is running on.
155 This assume that PTID is a valid ptid_t. Otherwise, a gdb_assert
156 will be triggered. */
159 ravenscar_get_thread_base_cpu (ptid_t ptid
)
163 if (is_ravenscar_task (ptid
))
165 struct ada_task_info
*task_info
= ada_get_task_info_from_ptid (ptid
);
167 gdb_assert (task_info
!= NULL
);
168 base_cpu
= task_info
->base_cpu
;
172 /* We assume that the LWP of the PTID is equal to the CPU number. */
173 base_cpu
= ptid
.lwp ();
179 /* Given a ravenscar task (identified by its ptid_t PTID), return true
180 if this task is the currently active task on the cpu that task is
183 In other words, this function determine which CPU this task is
184 currently running on, and then return nonzero if the CPU in question
185 is executing the code for that task. If that's the case, then
186 that task's registers are in the CPU bank. Otherwise, the task
187 is currently suspended, and its registers have been saved in memory. */
190 ravenscar_thread_target::task_is_currently_active (ptid_t ptid
)
192 ptid_t active_task_ptid
193 = active_task (ravenscar_get_thread_base_cpu (ptid
));
195 return ptid
== active_task_ptid
;
198 /* Return the CPU thread (as a ptid_t) on which the given ravenscar
201 This is the thread that corresponds to the CPU on which the task
205 get_base_thread_from_ravenscar_task (ptid_t ptid
)
209 if (!is_ravenscar_task (ptid
))
212 base_cpu
= ravenscar_get_thread_base_cpu (ptid
);
213 return ptid_t (ptid
.pid (), base_cpu
, 0);
216 /* Fetch the ravenscar running thread from target memory and
217 update inferior_ptid accordingly. */
220 ravenscar_thread_target::update_inferior_ptid ()
222 process_stratum_target
*proc_target
223 = as_process_stratum_target (this->beneath ());
227 m_base_ptid
= inferior_ptid
;
229 gdb_assert (!is_ravenscar_task (inferior_ptid
));
230 base_cpu
= ravenscar_get_thread_base_cpu (m_base_ptid
);
232 /* If the runtime has not been initialized yet, the inferior_ptid is
233 the only ptid that there is. */
234 if (!runtime_initialized ())
237 /* Make sure we set m_base_ptid before calling active_task
238 as the latter relies on it. */
239 inferior_ptid
= active_task (base_cpu
);
240 gdb_assert (inferior_ptid
!= null_ptid
);
242 /* The running thread may not have been added to
243 system.tasking.debug's list yet; so ravenscar_update_thread_list
244 may not always add it to the thread list. Add it here. */
245 if (!find_thread_ptid (proc_target
, inferior_ptid
))
246 add_thread (proc_target
, inferior_ptid
);
249 /* The Ravenscar Runtime exports a symbol which contains the ID of
250 the thread that is currently running. Try to locate that symbol
251 and return its associated minimal symbol.
252 Return NULL if not found. */
254 static struct bound_minimal_symbol
255 get_running_thread_msymbol ()
257 struct bound_minimal_symbol msym
;
259 msym
= lookup_minimal_symbol (running_thread_name
, NULL
, NULL
);
261 /* Older versions of the GNAT runtime were using a different
262 (less ideal) name for the symbol where the active thread ID
263 is stored. If we couldn't find the symbol using the latest
264 name, then try the old one. */
265 msym
= lookup_minimal_symbol ("running_thread", NULL
, NULL
);
270 /* Return True if the Ada Ravenscar run-time can be found in the
274 has_ravenscar_runtime ()
276 struct bound_minimal_symbol msym_ravenscar_runtime_initializer
277 = lookup_minimal_symbol (ravenscar_runtime_initializer
, NULL
, NULL
);
278 struct bound_minimal_symbol msym_known_tasks
279 = lookup_minimal_symbol (known_tasks_name
, NULL
, NULL
);
280 struct bound_minimal_symbol msym_first_task
281 = lookup_minimal_symbol (first_task_name
, NULL
, NULL
);
282 struct bound_minimal_symbol msym_running_thread
283 = get_running_thread_msymbol ();
285 return (msym_ravenscar_runtime_initializer
.minsym
286 && (msym_known_tasks
.minsym
|| msym_first_task
.minsym
)
287 && msym_running_thread
.minsym
);
290 /* Return True if the Ada Ravenscar run-time can be found in the
291 application, and if it has been initialized on target. */
294 ravenscar_thread_target::runtime_initialized ()
296 return active_task (1) != null_ptid
;
299 /* Return the ID of the thread that is currently running.
300 Return 0 if the ID could not be determined. */
303 get_running_thread_id (int cpu
)
305 struct bound_minimal_symbol object_msym
= get_running_thread_msymbol ();
309 CORE_ADDR object_addr
;
310 struct type
*builtin_type_void_data_ptr
311 = builtin_type (target_gdbarch ())->builtin_data_ptr
;
313 if (!object_msym
.minsym
)
316 object_size
= TYPE_LENGTH (builtin_type_void_data_ptr
);
317 object_addr
= (BMSYMBOL_VALUE_ADDRESS (object_msym
)
318 + (cpu
- 1) * object_size
);
319 buf_size
= object_size
;
320 buf
= (gdb_byte
*) alloca (buf_size
);
321 read_memory (object_addr
, buf
, buf_size
);
322 return extract_typed_address (buf
, builtin_type_void_data_ptr
);
326 ravenscar_thread_target::resume (ptid_t ptid
, int step
,
327 enum gdb_signal siggnal
)
329 /* If we see a wildcard resume, we simply pass that on. Otherwise,
330 arrange to resume the base ptid. */
331 inferior_ptid
= m_base_ptid
;
332 if (ptid
!= minus_one_ptid
)
334 beneath ()->resume (ptid
, step
, siggnal
);
338 ravenscar_thread_target::wait (ptid_t ptid
,
339 struct target_waitstatus
*status
,
342 process_stratum_target
*beneath
343 = as_process_stratum_target (this->beneath ());
346 inferior_ptid
= m_base_ptid
;
347 if (ptid
!= minus_one_ptid
)
349 event_ptid
= beneath
->wait (ptid
, status
, 0);
350 /* Find any new threads that might have been created, and update
351 inferior_ptid to the active thread.
353 Only do it if the program is still alive, though. Otherwise,
354 this causes problems when debugging through the remote protocol,
355 because we might try switching threads (and thus sending packets)
356 after the remote has disconnected. */
357 if (status
->kind
!= TARGET_WAITKIND_EXITED
358 && status
->kind
!= TARGET_WAITKIND_SIGNALLED
)
360 inferior_ptid
= event_ptid
;
361 this->update_thread_list ();
362 this->update_inferior_ptid ();
365 inferior_ptid
= m_base_ptid
;
366 return inferior_ptid
;
369 /* Add the thread associated to the given TASK to the thread list
370 (if the thread has already been added, this is a no-op). */
373 ravenscar_add_thread (struct ada_task_info
*task
)
375 if (find_thread_ptid (current_inferior (), task
->ptid
) == NULL
)
376 add_thread (current_inferior ()->process_target (), task
->ptid
);
380 ravenscar_thread_target::update_thread_list ()
382 /* Do not clear the thread list before adding the Ada task, to keep
383 the thread that the process stratum has included into it
384 (m_base_ptid) and the running thread, that may not have been included
385 to system.tasking.debug's list yet. */
387 iterate_over_live_ada_tasks (ravenscar_add_thread
);
391 ravenscar_thread_target::active_task (int cpu
)
393 CORE_ADDR tid
= get_running_thread_id (cpu
);
398 return ptid_t (m_base_ptid
.pid (), 0, tid
);
402 ravenscar_thread_target::extra_thread_info (thread_info
*tp
)
404 return "Ravenscar task";
408 ravenscar_thread_target::thread_alive (ptid_t ptid
)
410 /* Ravenscar tasks are non-terminating. */
415 ravenscar_thread_target::pid_to_str (ptid_t ptid
)
417 return string_printf ("Thread %#x", (int) ptid
.tid ());
421 ravenscar_thread_target::fetch_registers (struct regcache
*regcache
, int regnum
)
423 ptid_t ptid
= regcache
->ptid ();
425 if (runtime_initialized ()
426 && is_ravenscar_task (ptid
)
427 && !task_is_currently_active (ptid
))
429 struct gdbarch
*gdbarch
= regcache
->arch ();
430 struct ravenscar_arch_ops
*arch_ops
431 = gdbarch_ravenscar_ops (gdbarch
);
433 arch_ops
->fetch_registers (regcache
, regnum
);
436 beneath ()->fetch_registers (regcache
, regnum
);
440 ravenscar_thread_target::store_registers (struct regcache
*regcache
,
443 ptid_t ptid
= regcache
->ptid ();
445 if (runtime_initialized ()
446 && is_ravenscar_task (ptid
)
447 && !task_is_currently_active (ptid
))
449 struct gdbarch
*gdbarch
= regcache
->arch ();
450 struct ravenscar_arch_ops
*arch_ops
451 = gdbarch_ravenscar_ops (gdbarch
);
453 arch_ops
->store_registers (regcache
, regnum
);
456 beneath ()->store_registers (regcache
, regnum
);
460 ravenscar_thread_target::prepare_to_store (struct regcache
*regcache
)
462 ptid_t ptid
= regcache
->ptid ();
464 if (runtime_initialized ()
465 && is_ravenscar_task (ptid
)
466 && !task_is_currently_active (ptid
))
471 beneath ()->prepare_to_store (regcache
);
474 /* Implement the to_stopped_by_sw_breakpoint target_ops "method". */
477 ravenscar_thread_target::stopped_by_sw_breakpoint ()
479 scoped_restore save_ptid
= make_scoped_restore (&inferior_ptid
);
480 inferior_ptid
= get_base_thread_from_ravenscar_task (inferior_ptid
);
481 return beneath ()->stopped_by_sw_breakpoint ();
484 /* Implement the to_stopped_by_hw_breakpoint target_ops "method". */
487 ravenscar_thread_target::stopped_by_hw_breakpoint ()
489 scoped_restore save_ptid
= make_scoped_restore (&inferior_ptid
);
490 inferior_ptid
= get_base_thread_from_ravenscar_task (inferior_ptid
);
491 return beneath ()->stopped_by_hw_breakpoint ();
494 /* Implement the to_stopped_by_watchpoint target_ops "method". */
497 ravenscar_thread_target::stopped_by_watchpoint ()
499 scoped_restore save_ptid
= make_scoped_restore (&inferior_ptid
);
500 inferior_ptid
= get_base_thread_from_ravenscar_task (inferior_ptid
);
501 return beneath ()->stopped_by_watchpoint ();
504 /* Implement the to_stopped_data_address target_ops "method". */
507 ravenscar_thread_target::stopped_data_address (CORE_ADDR
*addr_p
)
509 scoped_restore save_ptid
= make_scoped_restore (&inferior_ptid
);
510 inferior_ptid
= get_base_thread_from_ravenscar_task (inferior_ptid
);
511 return beneath ()->stopped_data_address (addr_p
);
515 ravenscar_thread_target::mourn_inferior ()
517 m_base_ptid
= null_ptid
;
518 target_ops
*beneath
= this->beneath ();
519 unpush_target (this);
520 beneath
->mourn_inferior ();
523 /* Implement the to_core_of_thread target_ops "method". */
526 ravenscar_thread_target::core_of_thread (ptid_t ptid
)
528 scoped_restore save_ptid
= make_scoped_restore (&inferior_ptid
);
529 inferior_ptid
= get_base_thread_from_ravenscar_task (inferior_ptid
);
530 return beneath ()->core_of_thread (inferior_ptid
);
533 /* Observer on inferior_created: push ravenscar thread stratum if needed. */
536 ravenscar_inferior_created (struct target_ops
*target
, int from_tty
)
540 if (!ravenscar_task_support
541 || gdbarch_ravenscar_ops (target_gdbarch ()) == NULL
542 || !has_ravenscar_runtime ())
545 err_msg
= ada_get_tcb_types_info ();
548 warning (_("%s. Task/thread support disabled."), err_msg
);
552 target_ops_up
target_holder (new ravenscar_thread_target ());
553 push_target (std::move (target_holder
));
557 ravenscar_thread_target::get_ada_task_ptid (long lwp
, long thread
)
559 return ptid_t (m_base_ptid
.pid (), 0, thread
);
562 /* Command-list for the "set/show ravenscar" prefix command. */
563 static struct cmd_list_element
*set_ravenscar_list
;
564 static struct cmd_list_element
*show_ravenscar_list
;
566 /* Implement the "set ravenscar" prefix command. */
569 set_ravenscar_command (const char *arg
, int from_tty
)
571 printf_unfiltered (_(\
572 "\"set ravenscar\" must be followed by the name of a setting.\n"));
573 help_list (set_ravenscar_list
, "set ravenscar ", all_commands
, gdb_stdout
);
576 /* Implement the "show ravenscar" prefix command. */
579 show_ravenscar_command (const char *args
, int from_tty
)
581 cmd_show_list (show_ravenscar_list
, from_tty
, "");
584 /* Implement the "show ravenscar task-switching" command. */
587 show_ravenscar_task_switching_command (struct ui_file
*file
, int from_tty
,
588 struct cmd_list_element
*c
,
591 if (ravenscar_task_support
)
592 fprintf_filtered (file
, _("\
593 Support for Ravenscar task/thread switching is enabled\n"));
595 fprintf_filtered (file
, _("\
596 Support for Ravenscar task/thread switching is disabled\n"));
599 /* Module startup initialization function, automagically called by
602 void _initialize_ravenscar ();
604 _initialize_ravenscar ()
606 /* Notice when the inferior is created in order to push the
607 ravenscar ops if needed. */
608 gdb::observers::inferior_created
.attach (ravenscar_inferior_created
);
610 add_prefix_cmd ("ravenscar", no_class
, set_ravenscar_command
,
611 _("Prefix command for changing Ravenscar-specific settings."),
612 &set_ravenscar_list
, "set ravenscar ", 0, &setlist
);
614 add_prefix_cmd ("ravenscar", no_class
, show_ravenscar_command
,
615 _("Prefix command for showing Ravenscar-specific settings."),
616 &show_ravenscar_list
, "show ravenscar ", 0, &showlist
);
618 add_setshow_boolean_cmd ("task-switching", class_obscure
,
619 &ravenscar_task_support
, _("\
620 Enable or disable support for GNAT Ravenscar tasks."), _("\
621 Show whether support for GNAT Ravenscar tasks is enabled."),
623 Enable or disable support for task/thread switching with the GNAT\n\
624 Ravenscar run-time library for bareboard configuration."),
625 NULL
, show_ravenscar_task_switching_command
,
626 &set_ravenscar_list
, &show_ravenscar_list
);