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 ()
80 : m_base_ptid (inferior_ptid
)
82 thread_info
*thr
= add_active_thread ();
84 switch_to_thread (thr
);
87 const target_info
&info () const override
88 { return ravenscar_target_info
; }
90 strata
stratum () const override
{ return thread_stratum
; }
92 ptid_t
wait (ptid_t
, struct target_waitstatus
*, int) override
;
93 void resume (ptid_t
, int, enum gdb_signal
) override
;
95 void fetch_registers (struct regcache
*, int) override
;
96 void store_registers (struct regcache
*, int) override
;
98 void prepare_to_store (struct regcache
*) override
;
100 bool stopped_by_sw_breakpoint () override
;
102 bool stopped_by_hw_breakpoint () override
;
104 bool stopped_by_watchpoint () override
;
106 bool stopped_data_address (CORE_ADDR
*) override
;
108 bool thread_alive (ptid_t ptid
) override
;
110 int core_of_thread (ptid_t ptid
) override
;
112 void update_thread_list () override
;
114 const char *extra_thread_info (struct thread_info
*) override
;
116 std::string
pid_to_str (ptid_t
) override
;
118 ptid_t
get_ada_task_ptid (long lwp
, long thread
) override
;
120 void mourn_inferior () override
;
122 void close () override
129 /* PTID of the last thread that received an event.
130 This can be useful to determine the associated task that received
131 the event, to make it the current task. */
134 thread_info
*add_active_thread ();
135 ptid_t
active_task (int cpu
);
136 bool task_is_currently_active (ptid_t ptid
);
137 bool runtime_initialized ();
140 /* Return true iff PTID corresponds to a ravenscar task. */
143 is_ravenscar_task (ptid_t ptid
)
145 /* By construction, ravenscar tasks have their LWP set to zero.
146 Also make sure that the TID is nonzero, as some remotes, when
147 asked for the list of threads, will return the first thread
148 as having its TID set to zero. For instance, TSIM version
149 2.0.48 for LEON3 sends 'm0' as a reply to the 'qfThreadInfo'
150 query, which the remote protocol layer then treats as a thread
151 whose TID is 0. This is obviously not a ravenscar task. */
152 return ptid
.lwp () == 0 && ptid
.tid () != 0;
155 /* Given PTID, which can be either a ravenscar task or a CPU thread,
156 return which CPU that ptid is running on.
158 This assume that PTID is a valid ptid_t. Otherwise, a gdb_assert
159 will be triggered. */
162 ravenscar_get_thread_base_cpu (ptid_t ptid
)
166 if (is_ravenscar_task (ptid
))
168 struct ada_task_info
*task_info
= ada_get_task_info_from_ptid (ptid
);
170 gdb_assert (task_info
!= NULL
);
171 base_cpu
= task_info
->base_cpu
;
175 /* We assume that the LWP of the PTID is equal to the CPU number. */
176 base_cpu
= ptid
.lwp ();
182 /* Given a ravenscar task (identified by its ptid_t PTID), return true
183 if this task is the currently active task on the cpu that task is
186 In other words, this function determine which CPU this task is
187 currently running on, and then return nonzero if the CPU in question
188 is executing the code for that task. If that's the case, then
189 that task's registers are in the CPU bank. Otherwise, the task
190 is currently suspended, and its registers have been saved in memory. */
193 ravenscar_thread_target::task_is_currently_active (ptid_t ptid
)
195 ptid_t active_task_ptid
196 = active_task (ravenscar_get_thread_base_cpu (ptid
));
198 return ptid
== active_task_ptid
;
201 /* Return the CPU thread (as a ptid_t) on which the given ravenscar
204 This is the thread that corresponds to the CPU on which the task
208 get_base_thread_from_ravenscar_task (ptid_t ptid
)
212 if (!is_ravenscar_task (ptid
))
215 base_cpu
= ravenscar_get_thread_base_cpu (ptid
);
216 return ptid_t (ptid
.pid (), base_cpu
, 0);
219 /* Fetch the ravenscar running thread from target memory, make sure
220 there's a corresponding thread in the thread list, and return it.
221 If the runtime is not initialized, return NULL. */
224 ravenscar_thread_target::add_active_thread ()
226 process_stratum_target
*proc_target
227 = as_process_stratum_target (this->beneath ());
231 gdb_assert (!is_ravenscar_task (m_base_ptid
));
232 base_cpu
= ravenscar_get_thread_base_cpu (m_base_ptid
);
234 if (!runtime_initialized ())
237 /* Make sure we set m_base_ptid before calling active_task
238 as the latter relies on it. */
239 ptid_t active_ptid
= active_task (base_cpu
);
240 gdb_assert (active_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 thread_info
*active_thr
= find_thread_ptid (proc_target
, active_ptid
);
246 if (active_thr
== nullptr)
247 active_thr
= add_thread (proc_target
, active_ptid
);
251 /* The Ravenscar Runtime exports a symbol which contains the ID of
252 the thread that is currently running. Try to locate that symbol
253 and return its associated minimal symbol.
254 Return NULL if not found. */
256 static struct bound_minimal_symbol
257 get_running_thread_msymbol ()
259 struct bound_minimal_symbol msym
;
261 msym
= lookup_minimal_symbol (running_thread_name
, NULL
, NULL
);
263 /* Older versions of the GNAT runtime were using a different
264 (less ideal) name for the symbol where the active thread ID
265 is stored. If we couldn't find the symbol using the latest
266 name, then try the old one. */
267 msym
= lookup_minimal_symbol ("running_thread", NULL
, NULL
);
272 /* Return True if the Ada Ravenscar run-time can be found in the
276 has_ravenscar_runtime ()
278 struct bound_minimal_symbol msym_ravenscar_runtime_initializer
279 = lookup_minimal_symbol (ravenscar_runtime_initializer
, NULL
, NULL
);
280 struct bound_minimal_symbol msym_known_tasks
281 = lookup_minimal_symbol (known_tasks_name
, NULL
, NULL
);
282 struct bound_minimal_symbol msym_first_task
283 = lookup_minimal_symbol (first_task_name
, NULL
, NULL
);
284 struct bound_minimal_symbol msym_running_thread
285 = get_running_thread_msymbol ();
287 return (msym_ravenscar_runtime_initializer
.minsym
288 && (msym_known_tasks
.minsym
|| msym_first_task
.minsym
)
289 && msym_running_thread
.minsym
);
292 /* Return True if the Ada Ravenscar run-time can be found in the
293 application, and if it has been initialized on target. */
296 ravenscar_thread_target::runtime_initialized ()
298 return active_task (1) != null_ptid
;
301 /* Return the ID of the thread that is currently running.
302 Return 0 if the ID could not be determined. */
305 get_running_thread_id (int cpu
)
307 struct bound_minimal_symbol object_msym
= get_running_thread_msymbol ();
311 CORE_ADDR object_addr
;
312 struct type
*builtin_type_void_data_ptr
313 = builtin_type (target_gdbarch ())->builtin_data_ptr
;
315 if (!object_msym
.minsym
)
318 object_size
= TYPE_LENGTH (builtin_type_void_data_ptr
);
319 object_addr
= (BMSYMBOL_VALUE_ADDRESS (object_msym
)
320 + (cpu
- 1) * object_size
);
321 buf_size
= object_size
;
322 buf
= (gdb_byte
*) alloca (buf_size
);
323 read_memory (object_addr
, buf
, buf_size
);
324 return extract_typed_address (buf
, builtin_type_void_data_ptr
);
328 ravenscar_thread_target::resume (ptid_t ptid
, int step
,
329 enum gdb_signal siggnal
)
331 /* If we see a wildcard resume, we simply pass that on. Otherwise,
332 arrange to resume the base ptid. */
333 inferior_ptid
= m_base_ptid
;
334 if (ptid
!= minus_one_ptid
)
336 beneath ()->resume (ptid
, step
, siggnal
);
340 ravenscar_thread_target::wait (ptid_t ptid
,
341 struct target_waitstatus
*status
,
344 process_stratum_target
*beneath
345 = as_process_stratum_target (this->beneath ());
348 if (ptid
!= minus_one_ptid
)
350 event_ptid
= beneath
->wait (ptid
, status
, 0);
351 /* Find any new threads that might have been created, and return the
354 Only do it if the program is still alive, though. Otherwise,
355 this causes problems when debugging through the remote protocol,
356 because we might try switching threads (and thus sending packets)
357 after the remote has disconnected. */
358 if (status
->kind
!= TARGET_WAITKIND_EXITED
359 && status
->kind
!= TARGET_WAITKIND_SIGNALLED
)
361 m_base_ptid
= event_ptid
;
362 this->update_thread_list ();
363 return this->add_active_thread ()->ptid
;
368 /* Add the thread associated to the given TASK to the thread list
369 (if the thread has already been added, this is a no-op). */
372 ravenscar_add_thread (struct ada_task_info
*task
)
374 if (find_thread_ptid (current_inferior (), task
->ptid
) == NULL
)
375 add_thread (current_inferior ()->process_target (), task
->ptid
);
379 ravenscar_thread_target::update_thread_list ()
381 /* Do not clear the thread list before adding the Ada task, to keep
382 the thread that the process stratum has included into it
383 (m_base_ptid) and the running thread, that may not have been included
384 to system.tasking.debug's list yet. */
386 iterate_over_live_ada_tasks (ravenscar_add_thread
);
390 ravenscar_thread_target::active_task (int cpu
)
392 CORE_ADDR tid
= get_running_thread_id (cpu
);
397 return ptid_t (m_base_ptid
.pid (), 0, tid
);
401 ravenscar_thread_target::extra_thread_info (thread_info
*tp
)
403 return "Ravenscar task";
407 ravenscar_thread_target::thread_alive (ptid_t ptid
)
409 /* Ravenscar tasks are non-terminating. */
414 ravenscar_thread_target::pid_to_str (ptid_t ptid
)
416 return string_printf ("Thread %#x", (int) ptid
.tid ());
420 ravenscar_thread_target::fetch_registers (struct regcache
*regcache
, int regnum
)
422 ptid_t ptid
= regcache
->ptid ();
424 if (runtime_initialized ()
425 && is_ravenscar_task (ptid
)
426 && !task_is_currently_active (ptid
))
428 struct gdbarch
*gdbarch
= regcache
->arch ();
429 struct ravenscar_arch_ops
*arch_ops
430 = gdbarch_ravenscar_ops (gdbarch
);
432 arch_ops
->fetch_registers (regcache
, regnum
);
435 beneath ()->fetch_registers (regcache
, regnum
);
439 ravenscar_thread_target::store_registers (struct regcache
*regcache
,
442 ptid_t ptid
= regcache
->ptid ();
444 if (runtime_initialized ()
445 && is_ravenscar_task (ptid
)
446 && !task_is_currently_active (ptid
))
448 struct gdbarch
*gdbarch
= regcache
->arch ();
449 struct ravenscar_arch_ops
*arch_ops
450 = gdbarch_ravenscar_ops (gdbarch
);
452 arch_ops
->store_registers (regcache
, regnum
);
455 beneath ()->store_registers (regcache
, regnum
);
459 ravenscar_thread_target::prepare_to_store (struct regcache
*regcache
)
461 ptid_t ptid
= regcache
->ptid ();
463 if (runtime_initialized ()
464 && is_ravenscar_task (ptid
)
465 && !task_is_currently_active (ptid
))
470 beneath ()->prepare_to_store (regcache
);
473 /* Implement the to_stopped_by_sw_breakpoint target_ops "method". */
476 ravenscar_thread_target::stopped_by_sw_breakpoint ()
478 scoped_restore save_ptid
= make_scoped_restore (&inferior_ptid
);
479 inferior_ptid
= get_base_thread_from_ravenscar_task (inferior_ptid
);
480 return beneath ()->stopped_by_sw_breakpoint ();
483 /* Implement the to_stopped_by_hw_breakpoint target_ops "method". */
486 ravenscar_thread_target::stopped_by_hw_breakpoint ()
488 scoped_restore save_ptid
= make_scoped_restore (&inferior_ptid
);
489 inferior_ptid
= get_base_thread_from_ravenscar_task (inferior_ptid
);
490 return beneath ()->stopped_by_hw_breakpoint ();
493 /* Implement the to_stopped_by_watchpoint target_ops "method". */
496 ravenscar_thread_target::stopped_by_watchpoint ()
498 scoped_restore save_ptid
= make_scoped_restore (&inferior_ptid
);
499 inferior_ptid
= get_base_thread_from_ravenscar_task (inferior_ptid
);
500 return beneath ()->stopped_by_watchpoint ();
503 /* Implement the to_stopped_data_address target_ops "method". */
506 ravenscar_thread_target::stopped_data_address (CORE_ADDR
*addr_p
)
508 scoped_restore save_ptid
= make_scoped_restore (&inferior_ptid
);
509 inferior_ptid
= get_base_thread_from_ravenscar_task (inferior_ptid
);
510 return beneath ()->stopped_data_address (addr_p
);
514 ravenscar_thread_target::mourn_inferior ()
516 m_base_ptid
= null_ptid
;
517 target_ops
*beneath
= this->beneath ();
518 unpush_target (this);
519 beneath
->mourn_inferior ();
522 /* Implement the to_core_of_thread target_ops "method". */
525 ravenscar_thread_target::core_of_thread (ptid_t ptid
)
527 scoped_restore save_ptid
= make_scoped_restore (&inferior_ptid
);
528 inferior_ptid
= get_base_thread_from_ravenscar_task (inferior_ptid
);
529 return beneath ()->core_of_thread (inferior_ptid
);
532 /* Observer on inferior_created: push ravenscar thread stratum if needed. */
535 ravenscar_inferior_created (struct target_ops
*target
, int from_tty
)
539 if (!ravenscar_task_support
540 || gdbarch_ravenscar_ops (target_gdbarch ()) == NULL
541 || !has_ravenscar_runtime ())
544 err_msg
= ada_get_tcb_types_info ();
547 warning (_("%s. Task/thread support disabled."), err_msg
);
551 target_ops_up
target_holder (new ravenscar_thread_target ());
552 push_target (std::move (target_holder
));
556 ravenscar_thread_target::get_ada_task_ptid (long lwp
, long thread
)
558 return ptid_t (m_base_ptid
.pid (), 0, thread
);
561 /* Command-list for the "set/show ravenscar" prefix command. */
562 static struct cmd_list_element
*set_ravenscar_list
;
563 static struct cmd_list_element
*show_ravenscar_list
;
565 /* Implement the "show ravenscar task-switching" command. */
568 show_ravenscar_task_switching_command (struct ui_file
*file
, int from_tty
,
569 struct cmd_list_element
*c
,
572 if (ravenscar_task_support
)
573 fprintf_filtered (file
, _("\
574 Support for Ravenscar task/thread switching is enabled\n"));
576 fprintf_filtered (file
, _("\
577 Support for Ravenscar task/thread switching is disabled\n"));
580 /* Module startup initialization function, automagically called by
583 void _initialize_ravenscar ();
585 _initialize_ravenscar ()
587 /* Notice when the inferior is created in order to push the
588 ravenscar ops if needed. */
589 gdb::observers::inferior_created
.attach (ravenscar_inferior_created
);
591 add_basic_prefix_cmd ("ravenscar", no_class
,
592 _("Prefix command for changing Ravenscar-specific settings."),
593 &set_ravenscar_list
, "set ravenscar ", 0, &setlist
);
595 add_show_prefix_cmd ("ravenscar", no_class
,
596 _("Prefix command for showing Ravenscar-specific settings."),
597 &show_ravenscar_list
, "show ravenscar ", 0, &showlist
);
599 add_setshow_boolean_cmd ("task-switching", class_obscure
,
600 &ravenscar_task_support
, _("\
601 Enable or disable support for GNAT Ravenscar tasks."), _("\
602 Show whether support for GNAT Ravenscar tasks is enabled."),
604 Enable or disable support for task/thread switching with the GNAT\n\
605 Ravenscar run-time library for bareboard configuration."),
606 NULL
, show_ravenscar_task_switching_command
,
607 &set_ravenscar_list
, &show_ravenscar_list
);