1 /* Ada Ravenscar thread support.
3 Copyright (C) 2004-2017 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"
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 /* This module's target-specific operations. */
64 static struct target_ops ravenscar_ops;
66 /* PTID of the last thread that received an event.
67 This can be useful to determine the associated task that received
68 the event, to make it the current task. */
69 static ptid_t base_ptid;
71 static const char running_thread_name[] = "__gnat_running_thread_table";
73 static const char known_tasks_name[] = "system__tasking__debug__known_tasks";
74 static const char first_task_name[] = "system__tasking__debug__first_task";
76 static const char ravenscar_runtime_initializer[] =
77 "system__bb__threads__initialize";
79 static void ravenscar_update_thread_list (struct target_ops *ops);
80 static ptid_t ravenscar_active_task (int cpu);
81 static const char *ravenscar_extra_thread_info (struct target_ops *self,
82 struct thread_info *tp);
83 static int ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid);
84 static void ravenscar_fetch_registers (struct target_ops *ops,
85 struct regcache *regcache, int regnum);
86 static void ravenscar_store_registers (struct target_ops *ops,
87 struct regcache *regcache, int regnum);
88 static void ravenscar_prepare_to_store (struct target_ops *self,
89 struct regcache *regcache);
90 static void ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
91 enum gdb_signal siggnal);
92 static void ravenscar_mourn_inferior (struct target_ops *ops);
93 static void ravenscar_update_inferior_ptid (void);
94 static int has_ravenscar_runtime (void);
95 static int ravenscar_runtime_initialized (void);
96 static void ravenscar_inferior_created (struct target_ops *target,
99 /* Return nonzero iff PTID corresponds to a ravenscar task. */
102 is_ravenscar_task (ptid_t ptid)
104 /* By construction, ravenscar tasks have their LWP set to zero.
105 Also make sure that the TID is nonzero, as some remotes, when
106 asked for the list of threads, will return the first thread
107 as having its TID set to zero. For instance, TSIM version
108 2.0.48 for LEON3 sends 'm0' as a reply to the 'qfThreadInfo'
109 query, which the remote protocol layer then treats as a thread
110 whose TID is 0. This is obviously not a ravenscar task. */
111 return ptid_get_lwp (ptid) == 0 && ptid_get_tid (ptid) != 0;
114 /* Given PTID, which can be either a ravenscar task or a CPU thread,
115 return which CPU that ptid is running on.
117 This assume that PTID is a valid ptid_t. Otherwise, a gdb_assert
118 will be triggered. */
121 ravenscar_get_thread_base_cpu (ptid_t ptid)
125 if (is_ravenscar_task (ptid))
127 struct ada_task_info *task_info = ada_get_task_info_from_ptid (ptid);
129 gdb_assert (task_info != NULL);
130 base_cpu = task_info->base_cpu;
134 /* We assume that the LWP of the PTID is equal to the CPU number. */
135 base_cpu = ptid_get_lwp (ptid);
141 /* Given a ravenscar task (identified by its ptid_t PTID), return nonzero
142 if this task is the currently active task on the cpu that task is
145 In other words, this function determine which CPU this task is
146 currently running on, and then return nonzero if the CPU in question
147 is executing the code for that task. If that's the case, then
148 that task's registers are in the CPU bank. Otherwise, the task
149 is currently suspended, and its registers have been saved in memory. */
152 ravenscar_task_is_currently_active (ptid_t ptid)
154 ptid_t active_task_ptid
155 = ravenscar_active_task (ravenscar_get_thread_base_cpu (ptid));
157 return ptid_equal (ptid, active_task_ptid);
160 /* Return the CPU thread (as a ptid_t) on which the given ravenscar
163 This is the thread that corresponds to the CPU on which the task
167 get_base_thread_from_ravenscar_task (ptid_t ptid)
171 if (!is_ravenscar_task (ptid))
174 base_cpu = ravenscar_get_thread_base_cpu (ptid);
175 return ptid_build (ptid_get_pid (ptid), base_cpu, 0);
178 /* Fetch the ravenscar running thread from target memory and
179 update inferior_ptid accordingly. */
182 ravenscar_update_inferior_ptid (void)
186 base_ptid = inferior_ptid;
188 gdb_assert (!is_ravenscar_task (inferior_ptid));
189 base_cpu = ravenscar_get_thread_base_cpu (base_ptid);
191 /* If the runtime has not been initialized yet, the inferior_ptid is
192 the only ptid that there is. */
193 if (!ravenscar_runtime_initialized ())
196 /* Make sure we set base_ptid before calling ravenscar_active_task
197 as the latter relies on it. */
198 inferior_ptid = ravenscar_active_task (base_cpu);
199 gdb_assert (!ptid_equal (inferior_ptid, null_ptid));
201 /* The running thread may not have been added to
202 system.tasking.debug's list yet; so ravenscar_update_thread_list
203 may not always add it to the thread list. Add it here. */
204 if (!find_thread_ptid (inferior_ptid))
205 add_thread (inferior_ptid);
208 /* The Ravenscar Runtime exports a symbol which contains the ID of
209 the thread that is currently running. Try to locate that symbol
210 and return its associated minimal symbol.
211 Return NULL if not found. */
213 static struct bound_minimal_symbol
214 get_running_thread_msymbol (void)
216 struct bound_minimal_symbol msym;
218 msym = lookup_minimal_symbol (running_thread_name, NULL, NULL);
220 /* Older versions of the GNAT runtime were using a different
221 (less ideal) name for the symbol where the active thread ID
222 is stored. If we couldn't find the symbol using the latest
223 name, then try the old one. */
224 msym = lookup_minimal_symbol ("running_thread", NULL, NULL);
229 /* Return True if the Ada Ravenscar run-time can be found in the
233 has_ravenscar_runtime (void)
235 struct bound_minimal_symbol msym_ravenscar_runtime_initializer =
236 lookup_minimal_symbol (ravenscar_runtime_initializer, NULL, NULL);
237 struct bound_minimal_symbol msym_known_tasks =
238 lookup_minimal_symbol (known_tasks_name, NULL, NULL);
239 struct bound_minimal_symbol msym_first_task =
240 lookup_minimal_symbol (first_task_name, NULL, NULL);
241 struct bound_minimal_symbol msym_running_thread
242 = get_running_thread_msymbol ();
244 return (msym_ravenscar_runtime_initializer.minsym
245 && (msym_known_tasks.minsym || msym_first_task.minsym)
246 && msym_running_thread.minsym);
249 /* Return True if the Ada Ravenscar run-time can be found in the
250 application, and if it has been initialized on target. */
253 ravenscar_runtime_initialized (void)
255 return (!(ptid_equal (ravenscar_active_task (1), null_ptid)));
258 /* Return the ID of the thread that is currently running.
259 Return 0 if the ID could not be determined. */
262 get_running_thread_id (int cpu)
264 struct bound_minimal_symbol object_msym = get_running_thread_msymbol ();
268 CORE_ADDR object_addr;
269 struct type *builtin_type_void_data_ptr =
270 builtin_type (target_gdbarch ())->builtin_data_ptr;
272 if (!object_msym.minsym)
275 object_size = TYPE_LENGTH (builtin_type_void_data_ptr);
276 object_addr = (BMSYMBOL_VALUE_ADDRESS (object_msym)
277 + (cpu - 1) * object_size);
278 buf_size = object_size;
279 buf = (gdb_byte *) alloca (buf_size);
280 read_memory (object_addr, buf, buf_size);
281 return extract_typed_address (buf, builtin_type_void_data_ptr);
285 ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
286 enum gdb_signal siggnal)
288 struct target_ops *beneath = find_target_beneath (ops);
290 inferior_ptid = base_ptid;
291 beneath->to_resume (beneath, base_ptid, step, siggnal);
295 ravenscar_wait (struct target_ops *ops, ptid_t ptid,
296 struct target_waitstatus *status,
299 struct target_ops *beneath = find_target_beneath (ops);
301 inferior_ptid = base_ptid;
302 beneath->to_wait (beneath, base_ptid, status, 0);
303 /* Find any new threads that might have been created, and update
304 inferior_ptid to the active thread.
306 Only do it if the program is still alive, though. Otherwise,
307 this causes problems when debugging through the remote protocol,
308 because we might try switching threads (and thus sending packets)
309 after the remote has disconnected. */
310 if (status->kind != TARGET_WAITKIND_EXITED
311 && status->kind != TARGET_WAITKIND_SIGNALLED)
313 ravenscar_update_thread_list (ops);
314 ravenscar_update_inferior_ptid ();
316 return inferior_ptid;
319 /* Add the thread associated to the given TASK to the thread list
320 (if the thread has already been added, this is a no-op). */
323 ravenscar_add_thread (struct ada_task_info *task)
325 if (find_thread_ptid (task->ptid) == NULL)
326 add_thread (task->ptid);
330 ravenscar_update_thread_list (struct target_ops *ops)
332 ada_build_task_list ();
334 /* Do not clear the thread list before adding the Ada task, to keep
335 the thread that the process stratum has included into it
336 (base_ptid) and the running thread, that may not have been included
337 to system.tasking.debug's list yet. */
339 iterate_over_live_ada_tasks (ravenscar_add_thread);
343 ravenscar_active_task (int cpu)
345 CORE_ADDR tid = get_running_thread_id (cpu);
350 return ptid_build (ptid_get_pid (base_ptid), 0, tid);
354 ravenscar_extra_thread_info (struct target_ops *self, struct thread_info *tp)
356 return "Ravenscar task";
360 ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid)
362 /* Ravenscar tasks are non-terminating. */
367 ravenscar_pid_to_str (struct target_ops *ops, ptid_t ptid)
371 snprintf (buf, sizeof (buf), "Thread %#x", (int) ptid_get_tid (ptid));
376 ravenscar_fetch_registers (struct target_ops *ops,
377 struct regcache *regcache, int regnum)
379 struct target_ops *beneath = find_target_beneath (ops);
380 ptid_t ptid = regcache_get_ptid (regcache);
382 if (ravenscar_runtime_initialized ()
383 && is_ravenscar_task (ptid)
384 && !ravenscar_task_is_currently_active (ptid))
386 struct gdbarch *gdbarch = regcache->arch ();
387 struct ravenscar_arch_ops *arch_ops
388 = gdbarch_ravenscar_ops (gdbarch);
390 arch_ops->to_fetch_registers (regcache, regnum);
393 beneath->to_fetch_registers (beneath, regcache, regnum);
397 ravenscar_store_registers (struct target_ops *ops,
398 struct regcache *regcache, int regnum)
400 struct target_ops *beneath = find_target_beneath (ops);
401 ptid_t ptid = regcache_get_ptid (regcache);
403 if (ravenscar_runtime_initialized ()
404 && is_ravenscar_task (ptid)
405 && !ravenscar_task_is_currently_active (ptid))
407 struct gdbarch *gdbarch = regcache->arch ();
408 struct ravenscar_arch_ops *arch_ops
409 = gdbarch_ravenscar_ops (gdbarch);
411 arch_ops->to_store_registers (regcache, regnum);
414 beneath->to_store_registers (beneath, regcache, regnum);
418 ravenscar_prepare_to_store (struct target_ops *self,
419 struct regcache *regcache)
421 struct target_ops *beneath = find_target_beneath (self);
422 ptid_t ptid = regcache_get_ptid (regcache);
424 if (ravenscar_runtime_initialized ()
425 && is_ravenscar_task (ptid)
426 && !ravenscar_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->to_prepare_to_store (regcache);
435 beneath->to_prepare_to_store (beneath, regcache);
438 /* Implement the to_stopped_by_sw_breakpoint target_ops "method". */
441 ravenscar_stopped_by_sw_breakpoint (struct target_ops *ops)
443 ptid_t saved_ptid = inferior_ptid;
444 struct target_ops *beneath = find_target_beneath (ops);
447 inferior_ptid = get_base_thread_from_ravenscar_task (saved_ptid);
448 result = beneath->to_stopped_by_sw_breakpoint (beneath);
449 inferior_ptid = saved_ptid;
453 /* Implement the to_stopped_by_hw_breakpoint target_ops "method". */
456 ravenscar_stopped_by_hw_breakpoint (struct target_ops *ops)
458 ptid_t saved_ptid = inferior_ptid;
459 struct target_ops *beneath = find_target_beneath (ops);
462 inferior_ptid = get_base_thread_from_ravenscar_task (saved_ptid);
463 result = beneath->to_stopped_by_hw_breakpoint (beneath);
464 inferior_ptid = saved_ptid;
468 /* Implement the to_stopped_by_watchpoint target_ops "method". */
471 ravenscar_stopped_by_watchpoint (struct target_ops *ops)
473 ptid_t saved_ptid = inferior_ptid;
474 struct target_ops *beneath = find_target_beneath (ops);
477 inferior_ptid = get_base_thread_from_ravenscar_task (saved_ptid);
478 result = beneath->to_stopped_by_watchpoint (beneath);
479 inferior_ptid = saved_ptid;
483 /* Implement the to_stopped_data_address target_ops "method". */
486 ravenscar_stopped_data_address (struct target_ops *ops, CORE_ADDR *addr_p)
488 ptid_t saved_ptid = inferior_ptid;
489 struct target_ops *beneath = find_target_beneath (ops);
492 inferior_ptid = get_base_thread_from_ravenscar_task (saved_ptid);
493 result = beneath->to_stopped_data_address (beneath, addr_p);
494 inferior_ptid = saved_ptid;
499 ravenscar_mourn_inferior (struct target_ops *ops)
501 struct target_ops *beneath = find_target_beneath (ops);
503 base_ptid = null_ptid;
504 beneath->to_mourn_inferior (beneath);
505 unpush_target (&ravenscar_ops);
508 /* Implement the to_core_of_thread target_ops "method". */
511 ravenscar_core_of_thread (struct target_ops *ops, ptid_t ptid)
513 ptid_t saved_ptid = inferior_ptid;
514 struct target_ops *beneath = find_target_beneath (ops);
517 inferior_ptid = get_base_thread_from_ravenscar_task (saved_ptid);
518 result = beneath->to_core_of_thread (beneath, inferior_ptid);
519 inferior_ptid = saved_ptid;
523 /* Observer on inferior_created: push ravenscar thread stratum if needed. */
526 ravenscar_inferior_created (struct target_ops *target, int from_tty)
530 if (!ravenscar_task_support
531 || gdbarch_ravenscar_ops (target_gdbarch ()) == NULL
532 || !has_ravenscar_runtime ())
535 err_msg = ada_get_tcb_types_info ();
538 warning (_("%s. Task/thread support disabled.\n"), err_msg);
542 ravenscar_update_inferior_ptid ();
543 push_target (&ravenscar_ops);
547 ravenscar_get_ada_task_ptid (struct target_ops *self, long lwp, long thread)
549 return ptid_build (ptid_get_pid (base_ptid), 0, thread);
553 init_ravenscar_thread_ops (void)
555 ravenscar_ops.to_shortname = "ravenscar";
556 ravenscar_ops.to_longname = "Ravenscar tasks.";
557 ravenscar_ops.to_doc = "Ravenscar tasks support.";
558 ravenscar_ops.to_resume = ravenscar_resume;
559 ravenscar_ops.to_wait = ravenscar_wait;
560 ravenscar_ops.to_fetch_registers = ravenscar_fetch_registers;
561 ravenscar_ops.to_store_registers = ravenscar_store_registers;
562 ravenscar_ops.to_prepare_to_store = ravenscar_prepare_to_store;
563 ravenscar_ops.to_stopped_by_sw_breakpoint
564 = ravenscar_stopped_by_sw_breakpoint;
565 ravenscar_ops.to_stopped_by_hw_breakpoint
566 = ravenscar_stopped_by_hw_breakpoint;
567 ravenscar_ops.to_stopped_by_watchpoint = ravenscar_stopped_by_watchpoint;
568 ravenscar_ops.to_stopped_data_address = ravenscar_stopped_data_address;
569 ravenscar_ops.to_thread_alive = ravenscar_thread_alive;
570 ravenscar_ops.to_update_thread_list = ravenscar_update_thread_list;
571 ravenscar_ops.to_pid_to_str = ravenscar_pid_to_str;
572 ravenscar_ops.to_extra_thread_info = ravenscar_extra_thread_info;
573 ravenscar_ops.to_get_ada_task_ptid = ravenscar_get_ada_task_ptid;
574 ravenscar_ops.to_mourn_inferior = ravenscar_mourn_inferior;
575 ravenscar_ops.to_has_all_memory = default_child_has_all_memory;
576 ravenscar_ops.to_has_memory = default_child_has_memory;
577 ravenscar_ops.to_has_stack = default_child_has_stack;
578 ravenscar_ops.to_has_registers = default_child_has_registers;
579 ravenscar_ops.to_has_execution = default_child_has_execution;
580 ravenscar_ops.to_stratum = thread_stratum;
581 ravenscar_ops.to_core_of_thread = ravenscar_core_of_thread;
582 ravenscar_ops.to_magic = OPS_MAGIC;
585 /* Command-list for the "set/show ravenscar" prefix command. */
586 static struct cmd_list_element *set_ravenscar_list;
587 static struct cmd_list_element *show_ravenscar_list;
589 /* Implement the "set ravenscar" prefix command. */
592 set_ravenscar_command (const char *arg, int from_tty)
594 printf_unfiltered (_(\
595 "\"set ravenscar\" must be followed by the name of a setting.\n"));
596 help_list (set_ravenscar_list, "set ravenscar ", all_commands, gdb_stdout);
599 /* Implement the "show ravenscar" prefix command. */
602 show_ravenscar_command (const char *args, int from_tty)
604 cmd_show_list (show_ravenscar_list, from_tty, "");
607 /* Implement the "show ravenscar task-switching" command. */
610 show_ravenscar_task_switching_command (struct ui_file *file, int from_tty,
611 struct cmd_list_element *c,
614 if (ravenscar_task_support)
615 fprintf_filtered (file, _("\
616 Support for Ravenscar task/thread switching is enabled\n"));
618 fprintf_filtered (file, _("\
619 Support for Ravenscar task/thread switching is disabled\n"));
622 /* Module startup initialization function, automagically called by
626 _initialize_ravenscar (void)
628 init_ravenscar_thread_ops ();
629 base_ptid = null_ptid;
631 /* Notice when the inferior is created in order to push the
632 ravenscar ops if needed. */
633 observer_attach_inferior_created (ravenscar_inferior_created);
635 complete_target_initialization (&ravenscar_ops);
637 add_prefix_cmd ("ravenscar", no_class, set_ravenscar_command,
638 _("Prefix command for changing Ravenscar-specific settings"),
639 &set_ravenscar_list, "set ravenscar ", 0, &setlist);
641 add_prefix_cmd ("ravenscar", no_class, show_ravenscar_command,
642 _("Prefix command for showing Ravenscar-specific settings"),
643 &show_ravenscar_list, "show ravenscar ", 0, &showlist);
645 add_setshow_boolean_cmd ("task-switching", class_obscure,
646 &ravenscar_task_support, _("\
647 Enable or disable support for GNAT Ravenscar tasks"), _("\
648 Show whether support for GNAT Ravenscar tasks is enabled"),
650 Enable or disable support for task/thread switching with the GNAT\n\
651 Ravenscar run-time library for bareboard configuration."),
652 NULL, show_ravenscar_task_switching_command,
653 &set_ravenscar_list, &show_ravenscar_list);