1 /* Ada Ravenscar thread support.
3 Copyright (C) 2004-2019 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 comcepts 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 tasks. The convention
48 is that threads corresponding to the CPUs (see assumption above)
49 have a ptid_t of the form (PID, LWP, 0), which 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 tasks (or its underlying thread) is performed
54 by fetching the registers of that tasks 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 non-null, ravenscar task support is enabled. */
61 static int ravenscar_task_support = 1;
63 /* PTID of the last thread that received an event.
64 This can be useful to determine the associated task that received
65 the event, to make it the current task. */
66 static ptid_t base_ptid;
68 static const char running_thread_name[] = "__gnat_running_thread_table";
70 static const char known_tasks_name[] = "system__tasking__debug__known_tasks";
71 static const char first_task_name[] = "system__tasking__debug__first_task";
73 static const char ravenscar_runtime_initializer[] =
74 "system__bb__threads__initialize";
76 static const target_info ravenscar_target_info = {
78 N_("Ravenscar tasks."),
79 N_("Ravenscar tasks support.")
82 struct ravenscar_thread_target final : public target_ops
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 const char *pid_to_str (ptid_t) override;
115 ptid_t get_ada_task_ptid (long lwp, long thread) override;
117 void mourn_inferior () override;
120 /* This module's target-specific operations. */
121 static ravenscar_thread_target ravenscar_ops;
123 static ptid_t ravenscar_active_task (int cpu);
124 static void ravenscar_update_inferior_ptid (void);
125 static int has_ravenscar_runtime (void);
126 static int ravenscar_runtime_initialized (void);
127 static void ravenscar_inferior_created (struct target_ops *target,
130 /* Return nonzero iff PTID corresponds to a ravenscar task. */
133 is_ravenscar_task (ptid_t ptid)
135 /* By construction, ravenscar tasks have their LWP set to zero.
136 Also make sure that the TID is nonzero, as some remotes, when
137 asked for the list of threads, will return the first thread
138 as having its TID set to zero. For instance, TSIM version
139 2.0.48 for LEON3 sends 'm0' as a reply to the 'qfThreadInfo'
140 query, which the remote protocol layer then treats as a thread
141 whose TID is 0. This is obviously not a ravenscar task. */
142 return ptid.lwp () == 0 && ptid.tid () != 0;
145 /* Given PTID, which can be either a ravenscar task or a CPU thread,
146 return which CPU that ptid is running on.
148 This assume that PTID is a valid ptid_t. Otherwise, a gdb_assert
149 will be triggered. */
152 ravenscar_get_thread_base_cpu (ptid_t ptid)
156 if (is_ravenscar_task (ptid))
158 struct ada_task_info *task_info = ada_get_task_info_from_ptid (ptid);
160 gdb_assert (task_info != NULL);
161 base_cpu = task_info->base_cpu;
165 /* We assume that the LWP of the PTID is equal to the CPU number. */
166 base_cpu = ptid.lwp ();
172 /* Given a ravenscar task (identified by its ptid_t PTID), return nonzero
173 if this task is the currently active task on the cpu that task is
176 In other words, this function determine which CPU this task is
177 currently running on, and then return nonzero if the CPU in question
178 is executing the code for that task. If that's the case, then
179 that task's registers are in the CPU bank. Otherwise, the task
180 is currently suspended, and its registers have been saved in memory. */
183 ravenscar_task_is_currently_active (ptid_t ptid)
185 ptid_t active_task_ptid
186 = ravenscar_active_task (ravenscar_get_thread_base_cpu (ptid));
188 return ptid == active_task_ptid;
191 /* Return the CPU thread (as a ptid_t) on which the given ravenscar
194 This is the thread that corresponds to the CPU on which the task
198 get_base_thread_from_ravenscar_task (ptid_t ptid)
202 if (!is_ravenscar_task (ptid))
205 base_cpu = ravenscar_get_thread_base_cpu (ptid);
206 return ptid_t (ptid.pid (), base_cpu, 0);
209 /* Fetch the ravenscar running thread from target memory and
210 update inferior_ptid accordingly. */
213 ravenscar_update_inferior_ptid (void)
217 base_ptid = inferior_ptid;
219 gdb_assert (!is_ravenscar_task (inferior_ptid));
220 base_cpu = ravenscar_get_thread_base_cpu (base_ptid);
222 /* If the runtime has not been initialized yet, the inferior_ptid is
223 the only ptid that there is. */
224 if (!ravenscar_runtime_initialized ())
227 /* Make sure we set base_ptid before calling ravenscar_active_task
228 as the latter relies on it. */
229 inferior_ptid = ravenscar_active_task (base_cpu);
230 gdb_assert (inferior_ptid != null_ptid);
232 /* The running thread may not have been added to
233 system.tasking.debug's list yet; so ravenscar_update_thread_list
234 may not always add it to the thread list. Add it here. */
235 if (!find_thread_ptid (inferior_ptid))
236 add_thread (inferior_ptid);
239 /* The Ravenscar Runtime exports a symbol which contains the ID of
240 the thread that is currently running. Try to locate that symbol
241 and return its associated minimal symbol.
242 Return NULL if not found. */
244 static struct bound_minimal_symbol
245 get_running_thread_msymbol (void)
247 struct bound_minimal_symbol msym;
249 msym = lookup_minimal_symbol (running_thread_name, NULL, NULL);
251 /* Older versions of the GNAT runtime were using a different
252 (less ideal) name for the symbol where the active thread ID
253 is stored. If we couldn't find the symbol using the latest
254 name, then try the old one. */
255 msym = lookup_minimal_symbol ("running_thread", NULL, NULL);
260 /* Return True if the Ada Ravenscar run-time can be found in the
264 has_ravenscar_runtime (void)
266 struct bound_minimal_symbol msym_ravenscar_runtime_initializer =
267 lookup_minimal_symbol (ravenscar_runtime_initializer, NULL, NULL);
268 struct bound_minimal_symbol msym_known_tasks =
269 lookup_minimal_symbol (known_tasks_name, NULL, NULL);
270 struct bound_minimal_symbol msym_first_task =
271 lookup_minimal_symbol (first_task_name, NULL, NULL);
272 struct bound_minimal_symbol msym_running_thread
273 = get_running_thread_msymbol ();
275 return (msym_ravenscar_runtime_initializer.minsym
276 && (msym_known_tasks.minsym || msym_first_task.minsym)
277 && msym_running_thread.minsym);
280 /* Return True if the Ada Ravenscar run-time can be found in the
281 application, and if it has been initialized on target. */
284 ravenscar_runtime_initialized (void)
286 return (!(ravenscar_active_task (1) == null_ptid));
289 /* Return the ID of the thread that is currently running.
290 Return 0 if the ID could not be determined. */
293 get_running_thread_id (int cpu)
295 struct bound_minimal_symbol object_msym = get_running_thread_msymbol ();
299 CORE_ADDR object_addr;
300 struct type *builtin_type_void_data_ptr =
301 builtin_type (target_gdbarch ())->builtin_data_ptr;
303 if (!object_msym.minsym)
306 object_size = TYPE_LENGTH (builtin_type_void_data_ptr);
307 object_addr = (BMSYMBOL_VALUE_ADDRESS (object_msym)
308 + (cpu - 1) * object_size);
309 buf_size = object_size;
310 buf = (gdb_byte *) alloca (buf_size);
311 read_memory (object_addr, buf, buf_size);
312 return extract_typed_address (buf, builtin_type_void_data_ptr);
316 ravenscar_thread_target::resume (ptid_t ptid, int step, enum gdb_signal siggnal)
318 inferior_ptid = base_ptid;
319 beneath ()->resume (base_ptid, step, siggnal);
323 ravenscar_thread_target::wait (ptid_t ptid,
324 struct target_waitstatus *status,
329 inferior_ptid = base_ptid;
330 event_ptid = beneath ()->wait (base_ptid, status, 0);
331 /* Find any new threads that might have been created, and update
332 inferior_ptid to the active thread.
334 Only do it if the program is still alive, though. Otherwise,
335 this causes problems when debugging through the remote protocol,
336 because we might try switching threads (and thus sending packets)
337 after the remote has disconnected. */
338 if (status->kind != TARGET_WAITKIND_EXITED
339 && status->kind != TARGET_WAITKIND_SIGNALLED)
341 inferior_ptid = event_ptid;
342 this->update_thread_list ();
343 ravenscar_update_inferior_ptid ();
345 return inferior_ptid;
348 /* Add the thread associated to the given TASK to the thread list
349 (if the thread has already been added, this is a no-op). */
352 ravenscar_add_thread (struct ada_task_info *task)
354 if (find_thread_ptid (task->ptid) == NULL)
355 add_thread (task->ptid);
359 ravenscar_thread_target::update_thread_list ()
361 ada_build_task_list ();
363 /* Do not clear the thread list before adding the Ada task, to keep
364 the thread that the process stratum has included into it
365 (base_ptid) and the running thread, that may not have been included
366 to system.tasking.debug's list yet. */
368 iterate_over_live_ada_tasks (ravenscar_add_thread);
372 ravenscar_active_task (int cpu)
374 CORE_ADDR tid = get_running_thread_id (cpu);
379 return ptid_t (base_ptid.pid (), 0, tid);
383 ravenscar_thread_target::extra_thread_info (thread_info *tp)
385 return "Ravenscar task";
389 ravenscar_thread_target::thread_alive (ptid_t ptid)
391 /* Ravenscar tasks are non-terminating. */
396 ravenscar_thread_target::pid_to_str (ptid_t ptid)
400 snprintf (buf, sizeof (buf), "Thread %#x", (int) ptid.tid ());
405 ravenscar_thread_target::fetch_registers (struct regcache *regcache, int regnum)
407 ptid_t ptid = regcache->ptid ();
409 if (ravenscar_runtime_initialized ()
410 && is_ravenscar_task (ptid)
411 && !ravenscar_task_is_currently_active (ptid))
413 struct gdbarch *gdbarch = regcache->arch ();
414 struct ravenscar_arch_ops *arch_ops
415 = gdbarch_ravenscar_ops (gdbarch);
417 arch_ops->to_fetch_registers (regcache, regnum);
420 beneath ()->fetch_registers (regcache, regnum);
424 ravenscar_thread_target::store_registers (struct regcache *regcache,
427 ptid_t ptid = regcache->ptid ();
429 if (ravenscar_runtime_initialized ()
430 && is_ravenscar_task (ptid)
431 && !ravenscar_task_is_currently_active (ptid))
433 struct gdbarch *gdbarch = regcache->arch ();
434 struct ravenscar_arch_ops *arch_ops
435 = gdbarch_ravenscar_ops (gdbarch);
437 arch_ops->to_store_registers (regcache, regnum);
440 beneath ()->store_registers (regcache, regnum);
444 ravenscar_thread_target::prepare_to_store (struct regcache *regcache)
446 ptid_t ptid = regcache->ptid ();
448 if (ravenscar_runtime_initialized ()
449 && is_ravenscar_task (ptid)
450 && !ravenscar_task_is_currently_active (ptid))
452 struct gdbarch *gdbarch = regcache->arch ();
453 struct ravenscar_arch_ops *arch_ops
454 = gdbarch_ravenscar_ops (gdbarch);
456 arch_ops->to_prepare_to_store (regcache);
459 beneath ()->prepare_to_store (regcache);
462 /* Implement the to_stopped_by_sw_breakpoint target_ops "method". */
465 ravenscar_thread_target::stopped_by_sw_breakpoint ()
467 ptid_t saved_ptid = inferior_ptid;
470 inferior_ptid = get_base_thread_from_ravenscar_task (saved_ptid);
471 result = beneath ()->stopped_by_sw_breakpoint ();
472 inferior_ptid = saved_ptid;
476 /* Implement the to_stopped_by_hw_breakpoint target_ops "method". */
479 ravenscar_thread_target::stopped_by_hw_breakpoint ()
481 ptid_t saved_ptid = inferior_ptid;
484 inferior_ptid = get_base_thread_from_ravenscar_task (saved_ptid);
485 result = beneath ()->stopped_by_hw_breakpoint ();
486 inferior_ptid = saved_ptid;
490 /* Implement the to_stopped_by_watchpoint target_ops "method". */
493 ravenscar_thread_target::stopped_by_watchpoint ()
495 ptid_t saved_ptid = inferior_ptid;
498 inferior_ptid = get_base_thread_from_ravenscar_task (saved_ptid);
499 result = beneath ()->stopped_by_watchpoint ();
500 inferior_ptid = saved_ptid;
504 /* Implement the to_stopped_data_address target_ops "method". */
507 ravenscar_thread_target::stopped_data_address (CORE_ADDR *addr_p)
509 ptid_t saved_ptid = inferior_ptid;
512 inferior_ptid = get_base_thread_from_ravenscar_task (saved_ptid);
513 result = beneath ()->stopped_data_address (addr_p);
514 inferior_ptid = saved_ptid;
519 ravenscar_thread_target::mourn_inferior ()
521 base_ptid = null_ptid;
522 beneath ()->mourn_inferior ();
523 unpush_target (&ravenscar_ops);
526 /* Implement the to_core_of_thread target_ops "method". */
529 ravenscar_thread_target::core_of_thread (ptid_t ptid)
531 ptid_t saved_ptid = inferior_ptid;
534 inferior_ptid = get_base_thread_from_ravenscar_task (saved_ptid);
535 result = beneath ()->core_of_thread (inferior_ptid);
536 inferior_ptid = saved_ptid;
540 /* Observer on inferior_created: push ravenscar thread stratum if needed. */
543 ravenscar_inferior_created (struct target_ops *target, int from_tty)
547 if (!ravenscar_task_support
548 || gdbarch_ravenscar_ops (target_gdbarch ()) == NULL
549 || !has_ravenscar_runtime ())
552 err_msg = ada_get_tcb_types_info ();
555 warning (_("%s. Task/thread support disabled."), err_msg);
559 ravenscar_update_inferior_ptid ();
560 push_target (&ravenscar_ops);
564 ravenscar_thread_target::get_ada_task_ptid (long lwp, long thread)
566 return ptid_t (base_ptid.pid (), 0, thread);
569 /* Command-list for the "set/show ravenscar" prefix command. */
570 static struct cmd_list_element *set_ravenscar_list;
571 static struct cmd_list_element *show_ravenscar_list;
573 /* Implement the "set ravenscar" prefix command. */
576 set_ravenscar_command (const char *arg, int from_tty)
578 printf_unfiltered (_(\
579 "\"set ravenscar\" must be followed by the name of a setting.\n"));
580 help_list (set_ravenscar_list, "set ravenscar ", all_commands, gdb_stdout);
583 /* Implement the "show ravenscar" prefix command. */
586 show_ravenscar_command (const char *args, int from_tty)
588 cmd_show_list (show_ravenscar_list, from_tty, "");
591 /* Implement the "show ravenscar task-switching" command. */
594 show_ravenscar_task_switching_command (struct ui_file *file, int from_tty,
595 struct cmd_list_element *c,
598 if (ravenscar_task_support)
599 fprintf_filtered (file, _("\
600 Support for Ravenscar task/thread switching is enabled\n"));
602 fprintf_filtered (file, _("\
603 Support for Ravenscar task/thread switching is disabled\n"));
606 /* Module startup initialization function, automagically called by
610 _initialize_ravenscar (void)
612 base_ptid = null_ptid;
614 /* Notice when the inferior is created in order to push the
615 ravenscar ops if needed. */
616 gdb::observers::inferior_created.attach (ravenscar_inferior_created);
618 add_prefix_cmd ("ravenscar", no_class, set_ravenscar_command,
619 _("Prefix command for changing Ravenscar-specific settings"),
620 &set_ravenscar_list, "set ravenscar ", 0, &setlist);
622 add_prefix_cmd ("ravenscar", no_class, show_ravenscar_command,
623 _("Prefix command for showing Ravenscar-specific settings"),
624 &show_ravenscar_list, "show ravenscar ", 0, &showlist);
626 add_setshow_boolean_cmd ("task-switching", class_obscure,
627 &ravenscar_task_support, _("\
628 Enable or disable support for GNAT Ravenscar tasks"), _("\
629 Show whether support for GNAT Ravenscar tasks is enabled"),
631 Enable or disable support for task/thread switching with the GNAT\n\
632 Ravenscar run-time library for bareboard configuration."),
633 NULL, show_ravenscar_task_switching_command,
634 &set_ravenscar_list, &show_ravenscar_list);