gdb/ravenscar-thread.c

   1 /* Ada Ravenscar thread support.
   2
   3    Copyright 2004, 2009, 2010 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 "gdb_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 /* Non-null if the ravenscar thread layer has been pushed on the target
  38    stack.  */
  39 static int ravenscar_is_open = 0;
  40
  41 /* This module's target-specific operations.  */
  42 static struct target_ops ravenscar_ops;
  43
  44 /* Some base target uses a special value for the null PID (exempli gratia
  45    remote).  */
  46 static ptid_t base_magic_null_ptid;
  47
  48 /* Ptid of the inferior as seen by the process stratum.  */
  49 static ptid_t base_ptid;
  50
  51 static const char running_thread_name[] = "running_thread";
  52
  53 static const char known_tasks_name[] = "system__tasking__debug__known_tasks";
  54
  55 static const char ravenscar_runtime_initializer[] = "system__bb__threads__initialize";
  56
  57 static struct observer *update_target_observer = NULL;
  58
  59 /* Architecture-specific hooks.  */
  60 static struct ravenscar_arch_ops* current_arch_ops;
  61
  62 static CORE_ADDR read_thread_id (const char *symbol_name);
  63
  64 static void ravenscar_find_new_threads (struct target_ops *ops);
  65 static ptid_t ravenscar_running_thread (void);
  66 static char *ravenscar_extra_thread_info (struct thread_info *tp);
  67 static int ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid);
  68 static void ravenscar_fetch_registers (struct target_ops *ops,
  69                                        struct regcache *regcache, int regnum);
  70 static void ravenscar_store_registers (struct target_ops *ops,
  71                                        struct regcache *regcache, int regnum);
  72 static void ravenscar_prepare_to_store (struct regcache *regcache);
  73 static void ravenscar_initialize  (char *name, int from_tty);
  74 static void ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
  75                               enum target_signal siggnal);
  76 static void ravenscar_mourn_inferior (struct target_ops *ops);
  77 static void ravenscar_update_inferior_ptid (void);
  78 static int has_ravenscar_runtime (void);
  79 static int ravenscar_runtime_initialized (void);
  80 static void ravenscar_inferior_created (struct target_ops *target,
  81                                         int from_tty);
  82
  83 /* Fetch the ravenscar running thread from target memory and
  84    update inferior_ptid accordingly.  */
  85
  86 static void
  87 ravenscar_update_inferior_ptid (void)
  88 {
  89   base_ptid = inferior_ptid;
  90
  91   /* If the runtime has not been initialized yet, the inferior_ptid is
  92      the only ptid that there is.  */
  93   if (!ravenscar_runtime_initialized ())
  94     return;
  95
  96   /* Make sure we set base_ptid before calling ravenscar_running_thread
  97      as the latter relies on it.  */
  98   inferior_ptid = ravenscar_running_thread ();
  99   gdb_assert (!ptid_equal (inferior_ptid, null_ptid));
 100
 101   /* The running thread may not have been added to
 102      system.tasking.debug's list yet; so ravenscar_find_new_threads
 103      may not always add it to the thread list.  Add it here.  */
 104   if (!find_thread_ptid (inferior_ptid))
 105     add_thread (inferior_ptid);
 106 }
 107
 108 /* Return True if the Ada Ravenscar run-time can be found in the
 109    application.  */
 110
 111 static int
 112 has_ravenscar_runtime (void)
 113 {
 114   struct minimal_symbol *msym_ravenscar_runtime_initializer =
 115     lookup_minimal_symbol (ravenscar_runtime_initializer, NULL, NULL);
 116   struct minimal_symbol *msym_known_tasks =
 117     lookup_minimal_symbol (known_tasks_name, NULL, NULL);
 118   struct minimal_symbol *msym_running_thread =
 119     lookup_minimal_symbol (running_thread_name, NULL, NULL);
 120
 121   return (msym_ravenscar_runtime_initializer
 122           && msym_known_tasks
 123           && msym_running_thread);
 124 }
 125
 126 /* Return True if the Ada Ravenscar run-time can be found in the
 127    application, and if it has been initialized on target.  */
 128
 129 static int
 130 ravenscar_runtime_initialized (void)
 131 {
 132   return (!(ptid_equal (ravenscar_running_thread (), null_ptid)));
 133 }
 134
 135 /* Read the thread ID whose symbol name is SYMBOL_NAME.  */
 136
 137 static CORE_ADDR
 138 read_thread_id (const char *symbol_name)
 139 {
 140   const struct minimal_symbol *object_msym =
 141     lookup_minimal_symbol (symbol_name, NULL, NULL);
 142   int object_size;
 143   int buf_size;
 144   char *buf;
 145   CORE_ADDR object_addr;
 146   struct type *builtin_type_void_data_ptr =
 147     builtin_type (target_gdbarch)->builtin_data_ptr;
 148
 149   if (!object_msym)
 150     return 0;
 151
 152   object_addr = SYMBOL_VALUE_ADDRESS (object_msym);
 153   object_size = TYPE_LENGTH (builtin_type_void_data_ptr);
 154   buf_size = object_size;
 155   buf = alloca (buf_size);
 156   read_memory (object_addr, buf, buf_size);
 157   return extract_typed_address (buf, builtin_type_void_data_ptr);
 158 }
 159
 160 static void
 161 ravenscar_close (int quitting)
 162 {
 163   ravenscar_is_open = 0;
 164 }
 165
 166 static void
 167 ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
 168                   enum target_signal siggnal)
 169 {
 170   struct target_ops *beneath = find_target_beneath (ops);
 171
 172   inferior_ptid = base_ptid;
 173   beneath->to_resume (beneath, base_ptid, step, siggnal);
 174 }
 175
 176 static ptid_t
 177 ravenscar_wait (struct target_ops *ops, ptid_t ptid,
 178                 struct target_waitstatus *status,
 179                 int options)
 180 {
 181   struct target_ops *beneath = find_target_beneath (ops);
 182
 183   inferior_ptid = base_ptid;
 184   beneath->to_wait (beneath, base_ptid, status, 0);
 185   ravenscar_find_new_threads (ops);
 186   ravenscar_update_inferior_ptid ();
 187   return inferior_ptid;
 188 }
 189
 190 /* Add the thread associated to the given TASK to the thread list
 191    (if the thread has already been added, this is a no-op).  */
 192
 193 static void
 194 ravenscar_add_thread (struct ada_task_info *task)
 195 {
 196   if (find_thread_ptid (task->ptid) == NULL)
 197     add_thread (task->ptid);
 198 }
 199
 200 static void
 201 ravenscar_find_new_threads (struct target_ops *ops)
 202 {
 203   ada_build_task_list (0);
 204
 205   /* Do not clear the thread list before adding the Ada task, to keep
 206      the thread that the process stratum has included into it
 207      (base_ptid) and the running thread, that may not have been included
 208      to system.tasking.debug's list yet.  */
 209
 210   iterate_over_live_ada_tasks (ravenscar_add_thread);
 211 }
 212
 213 static ptid_t
 214 ravenscar_running_thread (void)
 215 {
 216   CORE_ADDR tid = read_thread_id (running_thread_name);
 217
 218   if (tid == 0)
 219     return null_ptid;
 220   else
 221     return ptid_build (ptid_get_pid (base_ptid), 0, tid);
 222 }
 223
 224 static char *
 225 ravenscar_extra_thread_info (struct thread_info *tp)
 226 {
 227   return "Ravenscar task";
 228 }
 229
 230 static int
 231 ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid)
 232 {
 233   /* Ravenscar tasks are non-terminating.  */
 234   return 1;
 235 }
 236
 237 static char *
 238 ravenscar_pid_to_str (struct target_ops *ops, ptid_t ptid)
 239 {
 240   static char buf[30];
 241
 242   snprintf (buf, sizeof (buf), "Thread %#x", (int) ptid_get_tid (ptid));
 243   return buf;
 244 }
 245
 246 static void
 247 ravenscar_fetch_registers (struct target_ops *ops,
 248                            struct regcache *regcache, int regnum)
 249 {
 250   struct target_ops *beneath = find_target_beneath (ops);
 251
 252   if (!ravenscar_runtime_initialized ()
 253       || ptid_equal (inferior_ptid, base_magic_null_ptid)
 254       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
 255     beneath->to_fetch_registers (beneath, regcache, regnum);
 256   else
 257     current_arch_ops->to_fetch_registers (regcache, regnum);
 258 }
 259
 260 static void
 261 ravenscar_store_registers (struct target_ops *ops,
 262                            struct regcache *regcache, int regnum)
 263 {
 264   struct target_ops *beneath = find_target_beneath (ops);
 265
 266   if (!ravenscar_runtime_initialized ()
 267       || ptid_equal (inferior_ptid, base_magic_null_ptid)
 268       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
 269     beneath->to_store_registers (beneath, regcache, regnum);
 270   else
 271     current_arch_ops->to_store_registers (regcache, regnum);
 272 }
 273
 274 static void
 275 ravenscar_prepare_to_store (struct regcache *regcache)
 276 {
 277   struct target_ops *beneath = find_target_beneath (&ravenscar_ops);
 278
 279   if (!ravenscar_runtime_initialized ()
 280       || ptid_equal (inferior_ptid, base_magic_null_ptid)
 281       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
 282     beneath->to_prepare_to_store (regcache);
 283   else
 284     current_arch_ops->to_prepare_to_store (regcache);
 285 }
 286
 287 static void
 288 ravenscar_mourn_inferior (struct target_ops *ops)
 289 {
 290   struct target_ops *beneath = find_target_beneath (&ravenscar_ops);
 291
 292   base_ptid = null_ptid;
 293   beneath->to_mourn_inferior (beneath);
 294   unpush_target (&ravenscar_ops);
 295 }
 296
 297 /* Observer on inferior_created: push ravenscar thread stratum if needed.  */
 298
 299 static void
 300 ravenscar_inferior_created (struct target_ops *target, int from_tty)
 301 {
 302   if (ravenscar_task_support
 303       && has_ravenscar_runtime ())
 304     ravenscar_initialize (NULL, 0);
 305 }
 306
 307 void
 308 ravenscar_register_arch_ops (struct ravenscar_arch_ops *ops)
 309 {
 310   /* FIXME: To be clean, we would need to handle a list of
 311      architectures, just like in remote-wtx-hw.c.  However, for now the
 312      only Ravenscar run-time for bare board that is implemented in
 313      GNAT is for only one architecture: erc32-elf.  So no need to care about
 314      that for now...*/
 315   current_arch_ops = ops;
 316 }
 317
 318 /* Initialize Ravenscar support.  */
 319
 320 static void
 321 ravenscar_initialize (char *name, int from_tty)
 322 {
 323   if (ravenscar_is_open)
 324     return;
 325
 326   base_magic_null_ptid = inferior_ptid;
 327   ravenscar_update_inferior_ptid ();
 328   push_target (&ravenscar_ops);
 329   ravenscar_is_open = 1;
 330 }
 331
 332 static ptid_t
 333 ravenscar_get_ada_task_ptid (long lwp, long thread)
 334 {
 335   return ptid_build (ptid_get_pid (base_ptid), 0, thread);
 336 }
 337
 338 static void
 339 init_ravenscar_thread_ops (void)
 340 {
 341   ravenscar_ops.to_shortname = "ravenscar";
 342   ravenscar_ops.to_longname = "Ravenscar tasks.";
 343   ravenscar_ops.to_doc = "Ravenscar tasks support.";
 344   ravenscar_ops.to_close = ravenscar_close;
 345   ravenscar_ops.to_resume = ravenscar_resume;
 346   ravenscar_ops.to_wait = ravenscar_wait;
 347   ravenscar_ops.to_fetch_registers = ravenscar_fetch_registers;
 348   ravenscar_ops.to_store_registers = ravenscar_store_registers;
 349   ravenscar_ops.to_prepare_to_store = ravenscar_prepare_to_store;
 350   ravenscar_ops.to_thread_alive = ravenscar_thread_alive;
 351   ravenscar_ops.to_find_new_threads = ravenscar_find_new_threads;
 352   ravenscar_ops.to_pid_to_str = ravenscar_pid_to_str;
 353   ravenscar_ops.to_extra_thread_info = ravenscar_extra_thread_info;
 354   ravenscar_ops.to_get_ada_task_ptid = ravenscar_get_ada_task_ptid;
 355   ravenscar_ops.to_mourn_inferior = ravenscar_mourn_inferior;
 356   ravenscar_ops.to_has_all_memory = default_child_has_all_memory;
 357   ravenscar_ops.to_has_memory = default_child_has_memory;
 358   ravenscar_ops.to_has_stack = default_child_has_stack;
 359   ravenscar_ops.to_has_registers = default_child_has_registers;
 360   ravenscar_ops.to_has_execution = default_child_has_execution;
 361   ravenscar_ops.to_stratum = thread_stratum;
 362   ravenscar_ops.to_magic = OPS_MAGIC;
 363 }
 364
 365 /* Command-list for the "set/show ravenscar" prefix command.  */
 366 static struct cmd_list_element *set_ravenscar_list;
 367 static struct cmd_list_element *show_ravenscar_list;
 368
 369 /* Implement the "set ravenscar" prefix command.  */
 370
 371 static void
 372 set_ravenscar_command (char *arg, int from_tty)
 373 {
 374   printf_unfiltered (_(\
 375 "\"set ravenscar\" must be followed by the name of a setting.\n"));
 376   help_list (set_ravenscar_list, "set ravenscar ", -1, gdb_stdout);
 377 }
 378
 379 /* Implement the "show ravenscar" prefix command.  */
 380
 381 static void
 382 show_ravenscar_command (char *args, int from_tty)
 383 {
 384   cmd_show_list (show_ravenscar_list, from_tty, "");
 385 }
 386
 387 /* Implement the "show ravenscar task-switching" command.  */
 388
 389 static void
 390 show_ravenscar_task_switching_command (struct ui_file *file, int from_tty,
 391                                        struct cmd_list_element *c,
 392                                        const char *value)
 393 {
 394   if (ravenscar_task_support)
 395     fprintf_filtered (file, _("\
 396 Support for Ravenscar task/thread switching is enabled"));
 397   else
 398     fprintf_filtered (file, _("\
 399 Support for Ravenscar task/thread switching is disabled"));
 400 }
 401
 402 /* Module startup initialization function, automagically called by
 403    init.c.  */
 404
 405 void
 406 _initialize_ravenscar (void)
 407 {
 408   init_ravenscar_thread_ops ();
 409   base_ptid = null_ptid;
 410
 411   /* Notice when the inferior is created in order to push the
 412      ravenscar ops if needed.  */
 413   observer_attach_inferior_created (ravenscar_inferior_created);
 414
 415   add_target (&ravenscar_ops);
 416
 417   add_prefix_cmd ("ravenscar", no_class, set_ravenscar_command,
 418                   _("Prefix command for changing Ravenscar-specific settings"),
 419                   &set_ravenscar_list, "set ravenscar ", 0, &setlist);
 420
 421   add_prefix_cmd ("ravenscar", no_class, show_ravenscar_command,
 422                   _("Prefix command for showing Ravenscar-specific settings"),
 423                   &show_ravenscar_list, "set ravenscar ", 0, &showlist);
 424
 425   add_setshow_boolean_cmd ("task-switching", class_obscure,
 426                            &ravenscar_task_support, _("\
 427 Enable or disable support for GNAT Ravenscar tasks"), _("\
 428 Show whether support for GNAT Ravenscar tasks is enabled"),
 429                            _("\
 430 Enable or disable support for task/thread switching with the GNAT\n\
 431 Ravenscar run-time library for bareboard configuration."),
 432                            NULL, show_ravenscar_task_switching_command,
 433                            &set_ravenscar_list, &show_ravenscar_list);
 434 }