gdb/ravenscar-thread.c

   1 /* Ada Ravenscar thread support.
   2
   3    Copyright (C) 2004-2014 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   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.
  11
  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.
  16
  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/>.  */
  19
  20 #include "defs.h"
  21 #include "gdbcore.h"
  22 #include "gdbthread.h"
  23 #include "ada-lang.h"
  24 #include "target.h"
  25 #include "inferior.h"
  26 #include "command.h"
  27 #include "ravenscar-thread.h"
  28 #include "observer.h"
  29 #include <string.h>
  30 #include "gdbcmd.h"
  31 #include "top.h"
  32 #include "regcache.h"
  33
  34 /* If non-null, ravenscar task support is enabled.  */
  35 static int ravenscar_task_support = 1;
  36
  37 /* This module's target-specific operations.  */
  38 static struct target_ops ravenscar_ops;
  39
  40 /* Some base target uses a special value for the null PID (exempli gratia
  41    remote).  */
  42 static ptid_t base_magic_null_ptid;
  43
  44 /* Ptid of the inferior as seen by the process stratum.  */
  45 static ptid_t base_ptid;
  46
  47 static const char running_thread_name[] = "__gnat_running_thread_table";
  48
  49 static const char known_tasks_name[] = "system__tasking__debug__known_tasks";
  50 static const char first_task_name[] = "system__tasking__debug__first_task";
  51
  52 static const char ravenscar_runtime_initializer[] =
  53   "system__bb__threads__initialize";
  54
  55 static void ravenscar_find_new_threads (struct target_ops *ops);
  56 static ptid_t ravenscar_running_thread (void);
  57 static char *ravenscar_extra_thread_info (struct thread_info *tp);
  58 static int ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid);
  59 static void ravenscar_fetch_registers (struct target_ops *ops,
  60                                        struct regcache *regcache, int regnum);
  61 static void ravenscar_store_registers (struct target_ops *ops,
  62                                        struct regcache *regcache, int regnum);
  63 static void ravenscar_prepare_to_store (struct target_ops *self,
  64                                         struct regcache *regcache);
  65 static void ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
  66                               enum gdb_signal siggnal);
  67 static void ravenscar_mourn_inferior (struct target_ops *ops);
  68 static void ravenscar_update_inferior_ptid (void);
  69 static int has_ravenscar_runtime (void);
  70 static int ravenscar_runtime_initialized (void);
  71 static void ravenscar_inferior_created (struct target_ops *target,
  72                                         int from_tty);
  73
  74 /* Fetch the ravenscar running thread from target memory and
  75    update inferior_ptid accordingly.  */
  76
  77 static void
  78 ravenscar_update_inferior_ptid (void)
  79 {
  80   base_ptid = inferior_ptid;
  81
  82   /* If the runtime has not been initialized yet, the inferior_ptid is
  83      the only ptid that there is.  */
  84   if (!ravenscar_runtime_initialized ())
  85     return;
  86
  87   /* Make sure we set base_ptid before calling ravenscar_running_thread
  88      as the latter relies on it.  */
  89   inferior_ptid = ravenscar_running_thread ();
  90   gdb_assert (!ptid_equal (inferior_ptid, null_ptid));
  91
  92   /* The running thread may not have been added to
  93      system.tasking.debug's list yet; so ravenscar_find_new_threads
  94      may not always add it to the thread list.  Add it here.  */
  95   if (!find_thread_ptid (inferior_ptid))
  96     add_thread (inferior_ptid);
  97 }
  98
  99 /* The Ravenscar Runtime exports a symbol which contains the ID of
 100    the thread that is currently running.  Try to locate that symbol
 101    and return its associated minimal symbol.
 102    Return NULL if not found.  */
 103
 104 static struct minimal_symbol *
 105 get_running_thread_msymbol (void)
 106 {
 107   struct minimal_symbol *msym;
 108
 109   msym = lookup_minimal_symbol (running_thread_name, NULL, NULL);
 110   if (!msym)
 111     /* Older versions of the GNAT runtime were using a different
 112        (less ideal) name for the symbol where the active thread ID
 113        is stored.  If we couldn't find the symbol using the latest
 114        name, then try the old one.  */
 115     msym = lookup_minimal_symbol ("running_thread", NULL, NULL);
 116
 117   return msym;
 118 }
 119
 120 /* Return True if the Ada Ravenscar run-time can be found in the
 121    application.  */
 122
 123 static int
 124 has_ravenscar_runtime (void)
 125 {
 126   struct minimal_symbol *msym_ravenscar_runtime_initializer =
 127     lookup_minimal_symbol (ravenscar_runtime_initializer, NULL, NULL);
 128   struct minimal_symbol *msym_known_tasks =
 129     lookup_minimal_symbol (known_tasks_name, NULL, NULL);
 130   struct minimal_symbol *msym_first_task =
 131     lookup_minimal_symbol (first_task_name, NULL, NULL);
 132   struct minimal_symbol *msym_running_thread = get_running_thread_msymbol ();
 133
 134   return (msym_ravenscar_runtime_initializer
 135           && (msym_known_tasks || msym_first_task)
 136           && msym_running_thread);
 137 }
 138
 139 /* Return True if the Ada Ravenscar run-time can be found in the
 140    application, and if it has been initialized on target.  */
 141
 142 static int
 143 ravenscar_runtime_initialized (void)
 144 {
 145   return (!(ptid_equal (ravenscar_running_thread (), null_ptid)));
 146 }
 147
 148 /* Return the ID of the thread that is currently running.
 149    Return 0 if the ID could not be determined.  */
 150
 151 static CORE_ADDR
 152 get_running_thread_id (void)
 153 {
 154   const struct minimal_symbol *object_msym = get_running_thread_msymbol ();
 155   int object_size;
 156   int buf_size;
 157   gdb_byte *buf;
 158   CORE_ADDR object_addr;
 159   struct type *builtin_type_void_data_ptr =
 160     builtin_type (target_gdbarch ())->builtin_data_ptr;
 161
 162   if (!object_msym)
 163     return 0;
 164
 165   object_addr = SYMBOL_VALUE_ADDRESS (object_msym);
 166   object_size = TYPE_LENGTH (builtin_type_void_data_ptr);
 167   buf_size = object_size;
 168   buf = alloca (buf_size);
 169   read_memory (object_addr, buf, buf_size);
 170   return extract_typed_address (buf, builtin_type_void_data_ptr);
 171 }
 172
 173 static void
 174 ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
 175                   enum gdb_signal siggnal)
 176 {
 177   struct target_ops *beneath = find_target_beneath (ops);
 178
 179   inferior_ptid = base_ptid;
 180   beneath->to_resume (beneath, base_ptid, step, siggnal);
 181 }
 182
 183 static ptid_t
 184 ravenscar_wait (struct target_ops *ops, ptid_t ptid,
 185                 struct target_waitstatus *status,
 186                 int options)
 187 {
 188   struct target_ops *beneath = find_target_beneath (ops);
 189
 190   inferior_ptid = base_ptid;
 191   beneath->to_wait (beneath, base_ptid, status, 0);
 192   /* Find any new threads that might have been created, and update
 193      inferior_ptid to the active thread.
 194
 195      Only do it if the program is still alive, though.  Otherwise,
 196      this causes problems when debugging through the remote protocol,
 197      because we might try switching threads (and thus sending packets)
 198      after the remote has disconnected.  */
 199   if (status->kind != TARGET_WAITKIND_EXITED
 200       && status->kind != TARGET_WAITKIND_SIGNALLED)
 201     {
 202       ravenscar_find_new_threads (ops);
 203       ravenscar_update_inferior_ptid ();
 204     }
 205   return inferior_ptid;
 206 }
 207
 208 /* Add the thread associated to the given TASK to the thread list
 209    (if the thread has already been added, this is a no-op).  */
 210
 211 static void
 212 ravenscar_add_thread (struct ada_task_info *task)
 213 {
 214   if (find_thread_ptid (task->ptid) == NULL)
 215     add_thread (task->ptid);
 216 }
 217
 218 static void
 219 ravenscar_find_new_threads (struct target_ops *ops)
 220 {
 221   ada_build_task_list ();
 222
 223   /* Do not clear the thread list before adding the Ada task, to keep
 224      the thread that the process stratum has included into it
 225      (base_ptid) and the running thread, that may not have been included
 226      to system.tasking.debug's list yet.  */
 227
 228   iterate_over_live_ada_tasks (ravenscar_add_thread);
 229 }
 230
 231 static ptid_t
 232 ravenscar_running_thread (void)
 233 {
 234   CORE_ADDR tid = get_running_thread_id ();
 235
 236   if (tid == 0)
 237     return null_ptid;
 238   else
 239     return ptid_build (ptid_get_pid (base_ptid), 0, tid);
 240 }
 241
 242 static char *
 243 ravenscar_extra_thread_info (struct thread_info *tp)
 244 {
 245   return "Ravenscar task";
 246 }
 247
 248 static int
 249 ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid)
 250 {
 251   /* Ravenscar tasks are non-terminating.  */
 252   return 1;
 253 }
 254
 255 static char *
 256 ravenscar_pid_to_str (struct target_ops *ops, ptid_t ptid)
 257 {
 258   static char buf[30];
 259
 260   snprintf (buf, sizeof (buf), "Thread %#x", (int) ptid_get_tid (ptid));
 261   return buf;
 262 }
 263
 264 static void
 265 ravenscar_fetch_registers (struct target_ops *ops,
 266                            struct regcache *regcache, int regnum)
 267 {
 268   struct target_ops *beneath = find_target_beneath (ops);
 269
 270   if (!ravenscar_runtime_initialized ()
 271       || ptid_equal (inferior_ptid, base_magic_null_ptid)
 272       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
 273     beneath->to_fetch_registers (beneath, regcache, regnum);
 274   else
 275     {
 276       struct gdbarch *gdbarch = get_regcache_arch (regcache);
 277       struct ravenscar_arch_ops *arch_ops
 278         = gdbarch_ravenscar_ops (gdbarch);
 279
 280       arch_ops->to_fetch_registers (regcache, regnum);
 281     }
 282 }
 283
 284 static void
 285 ravenscar_store_registers (struct target_ops *ops,
 286                            struct regcache *regcache, int regnum)
 287 {
 288   struct target_ops *beneath = find_target_beneath (ops);
 289
 290   if (!ravenscar_runtime_initialized ()
 291       || ptid_equal (inferior_ptid, base_magic_null_ptid)
 292       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
 293     beneath->to_store_registers (beneath, regcache, regnum);
 294   else
 295     {
 296       struct gdbarch *gdbarch = get_regcache_arch (regcache);
 297       struct ravenscar_arch_ops *arch_ops
 298         = gdbarch_ravenscar_ops (gdbarch);
 299
 300       arch_ops->to_store_registers (regcache, regnum);
 301     }
 302 }
 303
 304 static void
 305 ravenscar_prepare_to_store (struct target_ops *self,
 306                             struct regcache *regcache)
 307 {
 308   struct target_ops *beneath = find_target_beneath (&ravenscar_ops);
 309
 310   if (!ravenscar_runtime_initialized ()
 311       || ptid_equal (inferior_ptid, base_magic_null_ptid)
 312       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
 313     beneath->to_prepare_to_store (beneath, regcache);
 314   else
 315     {
 316       struct gdbarch *gdbarch = get_regcache_arch (regcache);
 317       struct ravenscar_arch_ops *arch_ops
 318         = gdbarch_ravenscar_ops (gdbarch);
 319
 320       arch_ops->to_prepare_to_store (regcache);
 321     }
 322 }
 323
 324 static void
 325 ravenscar_mourn_inferior (struct target_ops *ops)
 326 {
 327   struct target_ops *beneath = find_target_beneath (&ravenscar_ops);
 328
 329   base_ptid = null_ptid;
 330   beneath->to_mourn_inferior (beneath);
 331   unpush_target (&ravenscar_ops);
 332 }
 333
 334 /* Observer on inferior_created: push ravenscar thread stratum if needed.  */
 335
 336 static void
 337 ravenscar_inferior_created (struct target_ops *target, int from_tty)
 338 {
 339   struct ravenscar_arch_ops *ops;
 340
 341   if (!ravenscar_task_support
 342       || gdbarch_ravenscar_ops (current_inferior ()->gdbarch) == NULL
 343       || !has_ravenscar_runtime ())
 344     return;
 345
 346   base_magic_null_ptid = inferior_ptid;
 347   ravenscar_update_inferior_ptid ();
 348   push_target (&ravenscar_ops);
 349 }
 350
 351 static ptid_t
 352 ravenscar_get_ada_task_ptid (long lwp, long thread)
 353 {
 354   return ptid_build (ptid_get_pid (base_ptid), 0, thread);
 355 }
 356
 357 static void
 358 init_ravenscar_thread_ops (void)
 359 {
 360   ravenscar_ops.to_shortname = "ravenscar";
 361   ravenscar_ops.to_longname = "Ravenscar tasks.";
 362   ravenscar_ops.to_doc = "Ravenscar tasks support.";
 363   ravenscar_ops.to_resume = ravenscar_resume;
 364   ravenscar_ops.to_wait = ravenscar_wait;
 365   ravenscar_ops.to_fetch_registers = ravenscar_fetch_registers;
 366   ravenscar_ops.to_store_registers = ravenscar_store_registers;
 367   ravenscar_ops.to_prepare_to_store = ravenscar_prepare_to_store;
 368   ravenscar_ops.to_thread_alive = ravenscar_thread_alive;
 369   ravenscar_ops.to_find_new_threads = ravenscar_find_new_threads;
 370   ravenscar_ops.to_pid_to_str = ravenscar_pid_to_str;
 371   ravenscar_ops.to_extra_thread_info = ravenscar_extra_thread_info;
 372   ravenscar_ops.to_get_ada_task_ptid = ravenscar_get_ada_task_ptid;
 373   ravenscar_ops.to_mourn_inferior = ravenscar_mourn_inferior;
 374   ravenscar_ops.to_has_all_memory = default_child_has_all_memory;
 375   ravenscar_ops.to_has_memory = default_child_has_memory;
 376   ravenscar_ops.to_has_stack = default_child_has_stack;
 377   ravenscar_ops.to_has_registers = default_child_has_registers;
 378   ravenscar_ops.to_has_execution = default_child_has_execution;
 379   ravenscar_ops.to_stratum = thread_stratum;
 380   ravenscar_ops.to_magic = OPS_MAGIC;
 381 }
 382
 383 /* Command-list for the "set/show ravenscar" prefix command.  */
 384 static struct cmd_list_element *set_ravenscar_list;
 385 static struct cmd_list_element *show_ravenscar_list;
 386
 387 /* Implement the "set ravenscar" prefix command.  */
 388
 389 static void
 390 set_ravenscar_command (char *arg, int from_tty)
 391 {
 392   printf_unfiltered (_(\
 393 "\"set ravenscar\" must be followed by the name of a setting.\n"));
 394   help_list (set_ravenscar_list, "set ravenscar ", -1, gdb_stdout);
 395 }
 396
 397 /* Implement the "show ravenscar" prefix command.  */
 398
 399 static void
 400 show_ravenscar_command (char *args, int from_tty)
 401 {
 402   cmd_show_list (show_ravenscar_list, from_tty, "");
 403 }
 404
 405 /* Implement the "show ravenscar task-switching" command.  */
 406
 407 static void
 408 show_ravenscar_task_switching_command (struct ui_file *file, int from_tty,
 409                                        struct cmd_list_element *c,
 410                                        const char *value)
 411 {
 412   if (ravenscar_task_support)
 413     fprintf_filtered (file, _("\
 414 Support for Ravenscar task/thread switching is enabled\n"));
 415   else
 416     fprintf_filtered (file, _("\
 417 Support for Ravenscar task/thread switching is disabled\n"));
 418 }
 419
 420 /* Provide a prototype to silence -Wmissing-prototypes.  */
 421 extern void _initialize_ravenscar (void);
 422
 423 /* Module startup initialization function, automagically called by
 424    init.c.  */
 425
 426 void
 427 _initialize_ravenscar (void)
 428 {
 429   init_ravenscar_thread_ops ();
 430   base_ptid = null_ptid;
 431
 432   /* Notice when the inferior is created in order to push the
 433      ravenscar ops if needed.  */
 434   observer_attach_inferior_created (ravenscar_inferior_created);
 435
 436   complete_target_initialization (&ravenscar_ops);
 437
 438   add_prefix_cmd ("ravenscar", no_class, set_ravenscar_command,
 439                   _("Prefix command for changing Ravenscar-specific settings"),
 440                   &set_ravenscar_list, "set ravenscar ", 0, &setlist);
 441
 442   add_prefix_cmd ("ravenscar", no_class, show_ravenscar_command,
 443                   _("Prefix command for showing Ravenscar-specific settings"),
 444                   &show_ravenscar_list, "show ravenscar ", 0, &showlist);
 445
 446   add_setshow_boolean_cmd ("task-switching", class_obscure,
 447                            &ravenscar_task_support, _("\
 448 Enable or disable support for GNAT Ravenscar tasks"), _("\
 449 Show whether support for GNAT Ravenscar tasks is enabled"),
 450                            _("\
 451 Enable or disable support for task/thread switching with the GNAT\n\
 452 Ravenscar run-time library for bareboard configuration."),
 453                            NULL, show_ravenscar_task_switching_command,
 454                            &set_ravenscar_list, &show_ravenscar_list);
 455 }