gdb/gdbserver/target.c

   1 /* Target operations for the remote server for GDB.
   2    Copyright (C) 2002-2017 Free Software Foundation, Inc.
   3
   4    Contributed by MontaVista Software.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "server.h"
  22 #include "tracepoint.h"
  23
  24 struct target_ops *the_target;
  25
  26 int
  27 set_desired_thread ()
  28 {
  29   thread_info *found = find_thread_ptid (general_thread);
  30
  31   current_thread = found;
  32   return (current_thread != NULL);
  33 }
  34
  35 /* Structure used to look up a thread to use as current when accessing
  36    memory.  */
  37
  38 struct thread_search
  39 {
  40   /* The PTID of the current general thread.  This is an input
  41      parameter.  */
  42   ptid_t current_gen_ptid;
  43
  44   /* The first thread found.  */
  45   struct thread_info *first;
  46
  47   /* The first stopped thread found.  */
  48   struct thread_info *stopped;
  49
  50   /* The current general thread, if found.  */
  51   struct thread_info *current;
  52 };
  53
  54 /* Callback for find_inferior.  Search for a thread to use as current
  55    when accessing memory.  */
  56
  57 static int
  58 thread_search_callback (thread_info *thread, void *args)
  59 {
  60   struct thread_search *s = (struct thread_search *) args;
  61
  62   if (thread->id.pid () == ptid_get_pid (s->current_gen_ptid)
  63       && mythread_alive (ptid_of (thread)))
  64     {
  65       if (s->stopped == NULL
  66           && the_target->thread_stopped != NULL
  67           && thread_stopped (thread))
  68         s->stopped = thread;
  69
  70       if (s->first == NULL)
  71         s->first = thread;
  72
  73       if (s->current == NULL && s->current_gen_ptid == thread->id)
  74         s->current = thread;
  75     }
  76
  77   return 0;
  78 }
  79
  80 /* The thread that was current before prepare_to_access_memory was
  81    called.  done_accessing_memory uses this to restore the previous
  82    selected thread.  */
  83 static ptid_t prev_general_thread;
  84
  85 /* See target.h.  */
  86
  87 int
  88 prepare_to_access_memory (void)
  89 {
  90   struct thread_search search;
  91   struct thread_info *thread;
  92
  93   memset (&search, 0, sizeof (search));
  94   search.current_gen_ptid = general_thread;
  95   prev_general_thread = general_thread;
  96
  97   if (the_target->prepare_to_access_memory != NULL)
  98     {
  99       int res;
 100
 101       res = the_target->prepare_to_access_memory ();
 102       if (res != 0)
 103         return res;
 104     }
 105
 106   find_inferior (&all_threads, thread_search_callback, &search);
 107
 108   /* Prefer a stopped thread.  If none is found, try the current
 109      thread.  Otherwise, take the first thread in the process.  If
 110      none is found, undo the effects of
 111      target->prepare_to_access_memory() and return error.  */
 112   if (search.stopped != NULL)
 113     thread = search.stopped;
 114   else if (search.current != NULL)
 115     thread = search.current;
 116   else if (search.first != NULL)
 117     thread = search.first;
 118   else
 119     {
 120       done_accessing_memory ();
 121       return 1;
 122     }
 123
 124   current_thread = thread;
 125   general_thread = ptid_of (thread);
 126
 127   return 0;
 128 }
 129
 130 /* See target.h.  */
 131
 132 void
 133 done_accessing_memory (void)
 134 {
 135   if (the_target->done_accessing_memory != NULL)
 136     the_target->done_accessing_memory ();
 137
 138   /* Restore the previous selected thread.  */
 139   general_thread = prev_general_thread;
 140   switch_to_thread (general_thread);
 141 }
 142
 143 int
 144 read_inferior_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
 145 {
 146   int res;
 147   res = (*the_target->read_memory) (memaddr, myaddr, len);
 148   check_mem_read (memaddr, myaddr, len);
 149   return res;
 150 }
 151
 152 /* See target/target.h.  */
 153
 154 int
 155 target_read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
 156 {
 157   return read_inferior_memory (memaddr, myaddr, len);
 158 }
 159
 160 /* See target/target.h.  */
 161
 162 int
 163 target_read_uint32 (CORE_ADDR memaddr, uint32_t *result)
 164 {
 165   return read_inferior_memory (memaddr, (gdb_byte *) result, sizeof (*result));
 166 }
 167
 168 int
 169 write_inferior_memory (CORE_ADDR memaddr, const unsigned char *myaddr,
 170                        int len)
 171 {
 172   /* Lacking cleanups, there is some potential for a memory leak if the
 173      write fails and we go through error().  Make sure that no more than
 174      one buffer is ever pending by making BUFFER static.  */
 175   static unsigned char *buffer = 0;
 176   int res;
 177
 178   if (buffer != NULL)
 179     free (buffer);
 180
 181   buffer = (unsigned char *) xmalloc (len);
 182   memcpy (buffer, myaddr, len);
 183   check_mem_write (memaddr, buffer, myaddr, len);
 184   res = (*the_target->write_memory) (memaddr, buffer, len);
 185   free (buffer);
 186   buffer = NULL;
 187
 188   return res;
 189 }
 190
 191 /* See target/target.h.  */
 192
 193 int
 194 target_write_memory (CORE_ADDR memaddr, const gdb_byte *myaddr, ssize_t len)
 195 {
 196   return write_inferior_memory (memaddr, myaddr, len);
 197 }
 198
 199 ptid_t
 200 mywait (ptid_t ptid, struct target_waitstatus *ourstatus, int options,
 201         int connected_wait)
 202 {
 203   ptid_t ret;
 204
 205   if (connected_wait)
 206     server_waiting = 1;
 207
 208   ret = target_wait (ptid, ourstatus, options);
 209
 210   /* We don't expose _LOADED events to gdbserver core.  See the
 211      `dlls_changed' global.  */
 212   if (ourstatus->kind == TARGET_WAITKIND_LOADED)
 213     ourstatus->kind = TARGET_WAITKIND_STOPPED;
 214
 215   /* If GDB is connected through TCP/serial, then GDBserver will most
 216      probably be running on its own terminal/console, so it's nice to
 217      print there why is GDBserver exiting.  If however, GDB is
 218      connected through stdio, then there's no need to spam the GDB
 219      console with this -- the user will already see the exit through
 220      regular GDB output, in that same terminal.  */
 221   if (!remote_connection_is_stdio ())
 222     {
 223       if (ourstatus->kind == TARGET_WAITKIND_EXITED)
 224         fprintf (stderr,
 225                  "\nChild exited with status %d\n", ourstatus->value.integer);
 226       else if (ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
 227         fprintf (stderr, "\nChild terminated with signal = 0x%x (%s)\n",
 228                  gdb_signal_to_host (ourstatus->value.sig),
 229                  gdb_signal_to_name (ourstatus->value.sig));
 230     }
 231
 232   if (connected_wait)
 233     server_waiting = 0;
 234
 235   return ret;
 236 }
 237
 238 /* See target/target.h.  */
 239
 240 void
 241 target_stop_and_wait (ptid_t ptid)
 242 {
 243   struct target_waitstatus status;
 244   int was_non_stop = non_stop;
 245   struct thread_resume resume_info;
 246
 247   resume_info.thread = ptid;
 248   resume_info.kind = resume_stop;
 249   resume_info.sig = GDB_SIGNAL_0;
 250   (*the_target->resume) (&resume_info, 1);
 251
 252   non_stop = 1;
 253   mywait (ptid, &status, 0, 0);
 254   non_stop = was_non_stop;
 255 }
 256
 257 /* See target/target.h.  */
 258
 259 ptid_t
 260 target_wait (ptid_t ptid, struct target_waitstatus *status, int options)
 261 {
 262   return (*the_target->wait) (ptid, status, options);
 263 }
 264
 265 /* See target/target.h.  */
 266
 267 void
 268 target_mourn_inferior (ptid_t ptid)
 269 {
 270   (*the_target->mourn) (find_process_pid (ptid_get_pid (ptid)));
 271 }
 272
 273 /* See target/target.h.  */
 274
 275 void
 276 target_continue_no_signal (ptid_t ptid)
 277 {
 278   struct thread_resume resume_info;
 279
 280   resume_info.thread = ptid;
 281   resume_info.kind = resume_continue;
 282   resume_info.sig = GDB_SIGNAL_0;
 283   (*the_target->resume) (&resume_info, 1);
 284 }
 285
 286 /* See target/target.h.  */
 287
 288 void
 289 target_continue (ptid_t ptid, enum gdb_signal signal)
 290 {
 291   struct thread_resume resume_info;
 292
 293   resume_info.thread = ptid;
 294   resume_info.kind = resume_continue;
 295   resume_info.sig = gdb_signal_to_host (signal);
 296   (*the_target->resume) (&resume_info, 1);
 297 }
 298
 299 /* See target/target.h.  */
 300
 301 int
 302 target_supports_multi_process (void)
 303 {
 304   return (the_target->supports_multi_process != NULL ?
 305           (*the_target->supports_multi_process) () : 0);
 306 }
 307
 308 int
 309 start_non_stop (int nonstop)
 310 {
 311   if (the_target->start_non_stop == NULL)
 312     {
 313       if (nonstop)
 314         return -1;
 315       else
 316         return 0;
 317     }
 318
 319   return (*the_target->start_non_stop) (nonstop);
 320 }
 321
 322 void
 323 set_target_ops (struct target_ops *target)
 324 {
 325   the_target = XNEW (struct target_ops);
 326   memcpy (the_target, target, sizeof (*the_target));
 327 }
 328
 329 /* Convert pid to printable format.  */
 330
 331 const char *
 332 target_pid_to_str (ptid_t ptid)
 333 {
 334   static char buf[80];
 335
 336   if (ptid_equal (ptid, minus_one_ptid))
 337     xsnprintf (buf, sizeof (buf), "<all threads>");
 338   else if (ptid_equal (ptid, null_ptid))
 339     xsnprintf (buf, sizeof (buf), "<null thread>");
 340   else if (ptid_get_tid (ptid) != 0)
 341     xsnprintf (buf, sizeof (buf), "Thread %d.0x%lx",
 342                ptid_get_pid (ptid), ptid_get_tid (ptid));
 343   else if (ptid_get_lwp (ptid) != 0)
 344     xsnprintf (buf, sizeof (buf), "LWP %d.%ld",
 345                ptid_get_pid (ptid), ptid_get_lwp (ptid));
 346   else
 347     xsnprintf (buf, sizeof (buf), "Process %d",
 348                ptid_get_pid (ptid));
 349
 350   return buf;
 351 }
 352
 353 int
 354 kill_inferior (int pid)
 355 {
 356   gdb_agent_about_to_close (pid);
 357
 358   return (*the_target->kill) (pid);
 359 }
 360
 361 /* Target can do hardware single step.  */
 362
 363 int
 364 target_can_do_hardware_single_step (void)
 365 {
 366   return 1;
 367 }
 368
 369 /* Default implementation for breakpoint_kind_for_pc.
 370
 371    The default behavior for targets that don't implement breakpoint_kind_for_pc
 372    is to use the size of a breakpoint as the kind.  */
 373
 374 int
 375 default_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
 376 {
 377   int size = 0;
 378
 379   gdb_assert (the_target->sw_breakpoint_from_kind != NULL);
 380
 381   (*the_target->sw_breakpoint_from_kind) (0, &size);
 382   return size;
 383 }
 384
 385 /* Define it.  */
 386
 387 enum target_terminal::terminal_state target_terminal::terminal_state
 388   = target_terminal::terminal_is_ours;
 389
 390 /* See target/target.h.  */
 391
 392 void
 393 target_terminal::init ()
 394 {
 395   /* Placeholder needed because of fork_inferior.  Not necessary on
 396      GDBserver.  */
 397 }
 398
 399 /* See target/target.h.  */
 400
 401 void
 402 target_terminal::inferior ()
 403 {
 404   /* Placeholder needed because of fork_inferior.  Not necessary on
 405      GDBserver.  */
 406 }
 407
 408 /* See target/target.h.  */
 409
 410 void
 411 target_terminal::ours ()
 412 {
 413   /* Placeholder needed because of fork_inferior.  Not necessary on
 414      GDBserver.  */
 415 }
 416
 417 /* See target/target.h.  */
 418
 419 void
 420 target_terminal::ours_for_output (void)
 421 {
 422   /* Placeholder.  */
 423 }
 424
 425 /* See target/target.h.  */
 426
 427 void
 428 target_terminal::info (const char *arg, int from_tty)
 429 {
 430   /* Placeholder.  */
 431 }