gdb/ravenscar-thread.c

   1 /* Ada Ravenscar thread support.
   2
   3    Copyright 2004, 2009-2012 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[] = "__gnat_running_thread_table";
  52
  53 static const char known_tasks_name[] = "system__tasking__debug__known_tasks";
  54 static const char first_task_name[] = "system__tasking__debug__first_task";
  55
  56 static const char ravenscar_runtime_initializer[] =
  57   "system__bb__threads__initialize";
  58
  59 static struct observer *update_target_observer = NULL;
  60
  61 /* Architecture-specific hooks.  */
  62 static struct ravenscar_arch_ops* current_arch_ops;
  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 /* The Ravenscar Runtime exports a symbol which contains the ID of
 109    the thread that is currently running.  Try to locate that symbol
 110    and return its associated minimal symbol.
 111    Return NULL if not found.  */
 112
 113 static struct minimal_symbol *
 114 get_running_thread_msymbol (void)
 115 {
 116   struct minimal_symbol *msym;
 117
 118   msym = lookup_minimal_symbol (running_thread_name, NULL, NULL);
 119   if (!msym)
 120     /* Older versions of the GNAT runtime were using a different
 121        (less ideal) name for the symbol where the active thread ID
 122        is stored.  If we couldn't find the symbol using the latest
 123        name, then try the old one.  */
 124     msym = lookup_minimal_symbol ("running_thread", NULL, NULL);
 125
 126   return msym;
 127 }
 128
 129 /* Return True if the Ada Ravenscar run-time can be found in the
 130    application.  */
 131
 132 static int
 133 has_ravenscar_runtime (void)
 134 {
 135   struct minimal_symbol *msym_ravenscar_runtime_initializer =
 136     lookup_minimal_symbol (ravenscar_runtime_initializer, NULL, NULL);
 137   struct minimal_symbol *msym_known_tasks =
 138     lookup_minimal_symbol (known_tasks_name, NULL, NULL);
 139   struct minimal_symbol *msym_first_task =
 140     lookup_minimal_symbol (first_task_name, NULL, NULL);
 141   struct minimal_symbol *msym_running_thread = get_running_thread_msymbol ();
 142
 143   return (msym_ravenscar_runtime_initializer
 144           && (msym_known_tasks || msym_first_task)
 145           && msym_running_thread);
 146 }
 147
 148 /* Return True if the Ada Ravenscar run-time can be found in the
 149    application, and if it has been initialized on target.  */
 150
 151 static int
 152 ravenscar_runtime_initialized (void)
 153 {
 154   return (!(ptid_equal (ravenscar_running_thread (), null_ptid)));
 155 }
 156
 157 /* Return the ID of the thread that is currently running.
 158    Return 0 if the ID could not be determined.  */
 159
 160 static CORE_ADDR
 161 get_running_thread_id (void)
 162 {
 163   const struct minimal_symbol *object_msym = get_running_thread_msymbol ();
 164   int object_size;
 165   int buf_size;
 166   char *buf;
 167   CORE_ADDR object_addr;
 168   struct type *builtin_type_void_data_ptr =
 169     builtin_type (target_gdbarch)->builtin_data_ptr;
 170
 171   if (!object_msym)
 172     return 0;
 173
 174   object_addr = SYMBOL_VALUE_ADDRESS (object_msym);
 175   object_size = TYPE_LENGTH (builtin_type_void_data_ptr);
 176   buf_size = object_size;
 177   buf = alloca (buf_size);
 178   read_memory (object_addr, buf, buf_size);
 179   return extract_typed_address (buf, builtin_type_void_data_ptr);
 180 }
 181
 182 static void
 183 ravenscar_close (int quitting)
 184 {
 185   ravenscar_is_open = 0;
 186 }
 187
 188 static void
 189 ravenscar_resume (struct target_ops *ops, ptid_t ptid, int step,
 190                   enum target_signal siggnal)
 191 {
 192   struct target_ops *beneath = find_target_beneath (ops);
 193
 194   inferior_ptid = base_ptid;
 195   beneath->to_resume (beneath, base_ptid, step, siggnal);
 196 }
 197
 198 static ptid_t
 199 ravenscar_wait (struct target_ops *ops, ptid_t ptid,
 200                 struct target_waitstatus *status,
 201                 int options)
 202 {
 203   struct target_ops *beneath = find_target_beneath (ops);
 204
 205   inferior_ptid = base_ptid;
 206   beneath->to_wait (beneath, base_ptid, status, 0);
 207   ravenscar_find_new_threads (ops);
 208   ravenscar_update_inferior_ptid ();
 209   return inferior_ptid;
 210 }
 211
 212 /* Add the thread associated to the given TASK to the thread list
 213    (if the thread has already been added, this is a no-op).  */
 214
 215 static void
 216 ravenscar_add_thread (struct ada_task_info *task)
 217 {
 218   if (find_thread_ptid (task->ptid) == NULL)
 219     add_thread (task->ptid);
 220 }
 221
 222 static void
 223 ravenscar_find_new_threads (struct target_ops *ops)
 224 {
 225   ada_build_task_list ();
 226
 227   /* Do not clear the thread list before adding the Ada task, to keep
 228      the thread that the process stratum has included into it
 229      (base_ptid) and the running thread, that may not have been included
 230      to system.tasking.debug's list yet.  */
 231
 232   iterate_over_live_ada_tasks (ravenscar_add_thread);
 233 }
 234
 235 static ptid_t
 236 ravenscar_running_thread (void)
 237 {
 238   CORE_ADDR tid = get_running_thread_id ();
 239
 240   if (tid == 0)
 241     return null_ptid;
 242   else
 243     return ptid_build (ptid_get_pid (base_ptid), 0, tid);
 244 }
 245
 246 static char *
 247 ravenscar_extra_thread_info (struct thread_info *tp)
 248 {
 249   return "Ravenscar task";
 250 }
 251
 252 static int
 253 ravenscar_thread_alive (struct target_ops *ops, ptid_t ptid)
 254 {
 255   /* Ravenscar tasks are non-terminating.  */
 256   return 1;
 257 }
 258
 259 static char *
 260 ravenscar_pid_to_str (struct target_ops *ops, ptid_t ptid)
 261 {
 262   static char buf[30];
 263
 264   snprintf (buf, sizeof (buf), "Thread %#x", (int) ptid_get_tid (ptid));
 265   return buf;
 266 }
 267
 268 static void
 269 ravenscar_fetch_registers (struct target_ops *ops,
 270                            struct regcache *regcache, int regnum)
 271 {
 272   struct target_ops *beneath = find_target_beneath (ops);
 273
 274   if (!ravenscar_runtime_initialized ()
 275       || ptid_equal (inferior_ptid, base_magic_null_ptid)
 276       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
 277     beneath->to_fetch_registers (beneath, regcache, regnum);
 278   else
 279     current_arch_ops->to_fetch_registers (regcache, regnum);
 280 }
 281
 282 static void
 283 ravenscar_store_registers (struct target_ops *ops,
 284                            struct regcache *regcache, int regnum)
 285 {
 286   struct target_ops *beneath = find_target_beneath (ops);
 287
 288   if (!ravenscar_runtime_initialized ()
 289       || ptid_equal (inferior_ptid, base_magic_null_ptid)
 290       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
 291     beneath->to_store_registers (beneath, regcache, regnum);
 292   else
 293     current_arch_ops->to_store_registers (regcache, regnum);
 294 }
 295
 296 static void
 297 ravenscar_prepare_to_store (struct regcache *regcache)
 298 {
 299   struct target_ops *beneath = find_target_beneath (&ravenscar_ops);
 300
 301   if (!ravenscar_runtime_initialized ()
 302       || ptid_equal (inferior_ptid, base_magic_null_ptid)
 303       || ptid_equal (inferior_ptid, ravenscar_running_thread ()))
 304     beneath->to_prepare_to_store (regcache);
 305   else
 306     current_arch_ops->to_prepare_to_store (regcache);
 307 }
 308
 309 static void
 310 ravenscar_mourn_inferior (struct target_ops *ops)
 311 {
 312   struct target_ops *beneath = find_target_beneath (&ravenscar_ops);
 313
 314   base_ptid = null_ptid;
 315   beneath->to_mourn_inferior (beneath);
 316   unpush_target (&ravenscar_ops);
 317 }
 318
 319 /* Observer on inferior_created: push ravenscar thread stratum if needed.  */
 320
 321 static void
 322 ravenscar_inferior_created (struct target_ops *target, int from_tty)
 323 {
 324   if (ravenscar_task_support
 325       && has_ravenscar_runtime ())
 326     ravenscar_initialize (NULL, 0);
 327 }
 328
 329 void
 330 ravenscar_register_arch_ops (struct ravenscar_arch_ops *ops)
 331 {
 332   /* FIXME: To be clean, we would need to handle a list of
 333      architectures, just like in remote-wtx-hw.c.  However, for now the
 334      only Ravenscar run-time for bare board that is implemented in
 335      GNAT is for only one architecture: erc32-elf.  So no need to care about
 336      that for now...  */
 337   current_arch_ops = ops;
 338 }
 339
 340 /* Initialize Ravenscar support.  */
 341
 342 static void
 343 ravenscar_initialize (char *name, int from_tty)
 344 {
 345   if (ravenscar_is_open)
 346     return;
 347
 348   base_magic_null_ptid = inferior_ptid;
 349   ravenscar_update_inferior_ptid ();
 350   push_target (&ravenscar_ops);
 351   ravenscar_is_open = 1;
 352 }
 353
 354 static ptid_t
 355 ravenscar_get_ada_task_ptid (long lwp, long thread)
 356 {
 357   return ptid_build (ptid_get_pid (base_ptid), 0, thread);
 358 }
 359
 360 static void
 361 init_ravenscar_thread_ops (void)
 362 {
 363   ravenscar_ops.to_shortname = "ravenscar";
 364   ravenscar_ops.to_longname = "Ravenscar tasks.";
 365   ravenscar_ops.to_doc = "Ravenscar tasks support.";
 366   ravenscar_ops.to_close = ravenscar_close;
 367   ravenscar_ops.to_resume = ravenscar_resume;
 368   ravenscar_ops.to_wait = ravenscar_wait;
 369   ravenscar_ops.to_fetch_registers = ravenscar_fetch_registers;
 370   ravenscar_ops.to_store_registers = ravenscar_store_registers;
 371   ravenscar_ops.to_prepare_to_store = ravenscar_prepare_to_store;
 372   ravenscar_ops.to_thread_alive = ravenscar_thread_alive;
 373   ravenscar_ops.to_find_new_threads = ravenscar_find_new_threads;
 374   ravenscar_ops.to_pid_to_str = ravenscar_pid_to_str;
 375   ravenscar_ops.to_extra_thread_info = ravenscar_extra_thread_info;
 376   ravenscar_ops.to_get_ada_task_ptid = ravenscar_get_ada_task_ptid;
 377   ravenscar_ops.to_mourn_inferior = ravenscar_mourn_inferior;
 378   ravenscar_ops.to_has_all_memory = default_child_has_all_memory;
 379   ravenscar_ops.to_has_memory = default_child_has_memory;
 380   ravenscar_ops.to_has_stack = default_child_has_stack;
 381   ravenscar_ops.to_has_registers = default_child_has_registers;
 382   ravenscar_ops.to_has_execution = default_child_has_execution;
 383   ravenscar_ops.to_stratum = thread_stratum;
 384   ravenscar_ops.to_magic = OPS_MAGIC;
 385 }
 386
 387 /* Command-list for the "set/show ravenscar" prefix command.  */
 388 static struct cmd_list_element *set_ravenscar_list;
 389 static struct cmd_list_element *show_ravenscar_list;
 390
 391 /* Implement the "set ravenscar" prefix command.  */
 392
 393 static void
 394 set_ravenscar_command (char *arg, int from_tty)
 395 {
 396   printf_unfiltered (_(\
 397 "\"set ravenscar\" must be followed by the name of a setting.\n"));
 398   help_list (set_ravenscar_list, "set ravenscar ", -1, gdb_stdout);
 399 }
 400
 401 /* Implement the "show ravenscar" prefix command.  */
 402
 403 static void
 404 show_ravenscar_command (char *args, int from_tty)
 405 {
 406   cmd_show_list (show_ravenscar_list, from_tty, "");
 407 }
 408
 409 /* Implement the "show ravenscar task-switching" command.  */
 410
 411 static void
 412 show_ravenscar_task_switching_command (struct ui_file *file, int from_tty,
 413                                        struct cmd_list_element *c,
 414                                        const char *value)
 415 {
 416   if (ravenscar_task_support)
 417     fprintf_filtered (file, _("\
 418 Support for Ravenscar task/thread switching is enabled\n"));
 419   else
 420     fprintf_filtered (file, _("\
 421 Support for Ravenscar task/thread switching is disabled\n"));
 422 }
 423
 424 /* Provide a prototype to silence -Wmissing-prototypes.  */
 425 extern void _initialize_ravenscar (void);
 426
 427 /* Module startup initialization function, automagically called by
 428    init.c.  */
 429
 430 void
 431 _initialize_ravenscar (void)
 432 {
 433   init_ravenscar_thread_ops ();
 434   base_ptid = null_ptid;
 435
 436   /* Notice when the inferior is created in order to push the
 437      ravenscar ops if needed.  */
 438   observer_attach_inferior_created (ravenscar_inferior_created);
 439
 440   add_target (&ravenscar_ops);
 441
 442   add_prefix_cmd ("ravenscar", no_class, set_ravenscar_command,
 443                   _("Prefix command for changing Ravenscar-specific settings"),
 444                   &set_ravenscar_list, "set ravenscar ", 0, &setlist);
 445
 446   add_prefix_cmd ("ravenscar", no_class, show_ravenscar_command,
 447                   _("Prefix command for showing Ravenscar-specific settings"),
 448                   &show_ravenscar_list, "show ravenscar ", 0, &showlist);
 449
 450   add_setshow_boolean_cmd ("task-switching", class_obscure,
 451                            &ravenscar_task_support, _("\
 452 Enable or disable support for GNAT Ravenscar tasks"), _("\
 453 Show whether support for GNAT Ravenscar tasks is enabled"),
 454                            _("\
 455 Enable or disable support for task/thread switching with the GNAT\n\
 456 Ravenscar run-time library for bareboard configuration."),
 457                            NULL, show_ravenscar_task_switching_command,
 458                            &set_ravenscar_list, &show_ravenscar_list);
 459 }