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 (struct inferior_list_entry *entry, void *args)
  59 {
  60   struct thread_info *thread = (struct thread_info *) entry;
  61   struct thread_search *s = (struct thread_search *) args;
  62
  63   if (ptid_get_pid (entry->id) == ptid_get_pid (s->current_gen_ptid)
  64       && mythread_alive (ptid_of (thread)))
  65     {
  66       if (s->stopped == NULL
  67           && the_target->thread_stopped != NULL
  68           && thread_stopped (thread))
  69         s->stopped = thread;
  70
  71       if (s->first == NULL)
  72         s->first = thread;
  73
  74       if (s->current == NULL && ptid_equal (s->current_gen_ptid, entry->id))
  75         s->current = thread;
  76     }
  77
  78   return 0;
  79 }
  80
  81 /* The thread that was current before prepare_to_access_memory was
  82    called.  done_accessing_memory uses this to restore the previous
  83    selected thread.  */
  84 static ptid_t prev_general_thread;
  85
  86 /* See target.h.  */
  87
  88 int
  89 prepare_to_access_memory (void)
  90 {
  91   struct thread_search search;
  92   struct thread_info *thread;
  93
  94   memset (&search, 0, sizeof (search));
  95   search.current_gen_ptid = general_thread;
  96   prev_general_thread = general_thread;
  97
  98   if (the_target->prepare_to_access_memory != NULL)
  99     {
 100       int res;
 101
 102       res = the_target->prepare_to_access_memory ();
 103       if (res != 0)
 104         return res;
 105     }
 106
 107   find_inferior (&all_threads, thread_search_callback, &search);
 108
 109   /* Prefer a stopped thread.  If none is found, try the current
 110      thread.  Otherwise, take the first thread in the process.  If
 111      none is found, undo the effects of
 112      target->prepare_to_access_memory() and return error.  */
 113   if (search.stopped != NULL)
 114     thread = search.stopped;
 115   else if (search.current != NULL)
 116     thread = search.current;
 117   else if (search.first != NULL)
 118     thread = search.first;
 119   else
 120     {
 121       done_accessing_memory ();
 122       return 1;
 123     }
 124
 125   current_thread = thread;
 126   general_thread = ptid_of (thread);
 127
 128   return 0;
 129 }
 130
 131 /* See target.h.  */
 132
 133 void
 134 done_accessing_memory (void)
 135 {
 136   if (the_target->done_accessing_memory != NULL)
 137     the_target->done_accessing_memory ();
 138
 139   /* Restore the previous selected thread.  */
 140   general_thread = prev_general_thread;
 141   switch_to_thread (general_thread);
 142 }
 143
 144 int
 145 read_inferior_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
 146 {
 147   int res;
 148   res = (*the_target->read_memory) (memaddr, myaddr, len);
 149   check_mem_read (memaddr, myaddr, len);
 150   return res;
 151 }
 152
 153 /* See target/target.h.  */
 154
 155 int
 156 target_read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
 157 {
 158   return read_inferior_memory (memaddr, myaddr, len);
 159 }
 160
 161 /* See target/target.h.  */
 162
 163 int
 164 target_read_uint32 (CORE_ADDR memaddr, uint32_t *result)
 165 {
 166   return read_inferior_memory (memaddr, (gdb_byte *) result, sizeof (*result));
 167 }
 168
 169 int
 170 write_inferior_memory (CORE_ADDR memaddr, const unsigned char *myaddr,
 171                        int len)
 172 {
 173   /* Lacking cleanups, there is some potential for a memory leak if the
 174      write fails and we go through error().  Make sure that no more than
 175      one buffer is ever pending by making BUFFER static.  */
 176   static unsigned char *buffer = 0;
 177   int res;
 178
 179   if (buffer != NULL)
 180     free (buffer);
 181
 182   buffer = (unsigned char *) xmalloc (len);
 183   memcpy (buffer, myaddr, len);
 184   check_mem_write (memaddr, buffer, myaddr, len);
 185   res = (*the_target->write_memory) (memaddr, buffer, len);
 186   free (buffer);
 187   buffer = NULL;
 188
 189   return res;
 190 }
 191
 192 /* See target/target.h.  */
 193
 194 int
 195 target_write_memory (CORE_ADDR memaddr, const gdb_byte *myaddr, ssize_t len)
 196 {
 197   return write_inferior_memory (memaddr, myaddr, len);
 198 }
 199
 200 ptid_t
 201 mywait (ptid_t ptid, struct target_waitstatus *ourstatus, int options,
 202         int connected_wait)
 203 {
 204   ptid_t ret;
 205
 206   if (connected_wait)
 207     server_waiting = 1;
 208
 209   ret = target_wait (ptid, ourstatus, options);
 210
 211   /* We don't expose _LOADED events to gdbserver core.  See the
 212      `dlls_changed' global.  */
 213   if (ourstatus->kind == TARGET_WAITKIND_LOADED)
 214     ourstatus->kind = TARGET_WAITKIND_STOPPED;
 215
 216   /* If GDB is connected through TCP/serial, then GDBserver will most
 217      probably be running on its own terminal/console, so it's nice to
 218      print there why is GDBserver exiting.  If however, GDB is
 219      connected through stdio, then there's no need to spam the GDB
 220      console with this -- the user will already see the exit through
 221      regular GDB output, in that same terminal.  */
 222   if (!remote_connection_is_stdio ())
 223     {
 224       if (ourstatus->kind == TARGET_WAITKIND_EXITED)
 225         fprintf (stderr,
 226                  "\nChild exited with status %d\n", ourstatus->value.integer);
 227       else if (ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
 228         fprintf (stderr, "\nChild terminated with signal = 0x%x (%s)\n",
 229                  gdb_signal_to_host (ourstatus->value.sig),
 230                  gdb_signal_to_name (ourstatus->value.sig));
 231     }
 232
 233   if (connected_wait)
 234     server_waiting = 0;
 235
 236   return ret;
 237 }
 238
 239 /* See target/target.h.  */
 240
 241 void
 242 target_stop_and_wait (ptid_t ptid)
 243 {
 244   struct target_waitstatus status;
 245   int was_non_stop = non_stop;
 246   struct thread_resume resume_info;
 247
 248   resume_info.thread = ptid;
 249   resume_info.kind = resume_stop;
 250   resume_info.sig = GDB_SIGNAL_0;
 251   (*the_target->resume) (&resume_info, 1);
 252
 253   non_stop = 1;
 254   mywait (ptid, &status, 0, 0);
 255   non_stop = was_non_stop;
 256 }
 257
 258 /* See target/target.h.  */
 259
 260 ptid_t
 261 target_wait (ptid_t ptid, struct target_waitstatus *status, int options)
 262 {
 263   return (*the_target->wait) (ptid, status, options);
 264 }
 265
 266 /* See target/target.h.  */
 267
 268 void
 269 target_mourn_inferior (ptid_t ptid)
 270 {
 271   (*the_target->mourn) (find_process_pid (ptid_get_pid (ptid)));
 272 }
 273
 274 /* See target/target.h.  */
 275
 276 void
 277 target_continue_no_signal (ptid_t ptid)
 278 {
 279   struct thread_resume resume_info;
 280
 281   resume_info.thread = ptid;
 282   resume_info.kind = resume_continue;
 283   resume_info.sig = GDB_SIGNAL_0;
 284   (*the_target->resume) (&resume_info, 1);
 285 }
 286
 287 /* See target/target.h.  */
 288
 289 void
 290 target_continue (ptid_t ptid, enum gdb_signal signal)
 291 {
 292   struct thread_resume resume_info;
 293
 294   resume_info.thread = ptid;
 295   resume_info.kind = resume_continue;
 296   resume_info.sig = gdb_signal_to_host (signal);
 297   (*the_target->resume) (&resume_info, 1);
 298 }
 299
 300 /* See target/target.h.  */
 301
 302 int
 303 target_supports_multi_process (void)
 304 {
 305   return (the_target->supports_multi_process != NULL ?
 306           (*the_target->supports_multi_process) () : 0);
 307 }
 308
 309 int
 310 start_non_stop (int nonstop)
 311 {
 312   if (the_target->start_non_stop == NULL)
 313     {
 314       if (nonstop)
 315         return -1;
 316       else
 317         return 0;
 318     }
 319
 320   return (*the_target->start_non_stop) (nonstop);
 321 }
 322
 323 void
 324 set_target_ops (struct target_ops *target)
 325 {
 326   the_target = XNEW (struct target_ops);
 327   memcpy (the_target, target, sizeof (*the_target));
 328 }
 329
 330 /* Convert pid to printable format.  */
 331
 332 const char *
 333 target_pid_to_str (ptid_t ptid)
 334 {
 335   static char buf[80];
 336
 337   if (ptid_equal (ptid, minus_one_ptid))
 338     xsnprintf (buf, sizeof (buf), "<all threads>");
 339   else if (ptid_equal (ptid, null_ptid))
 340     xsnprintf (buf, sizeof (buf), "<null thread>");
 341   else if (ptid_get_tid (ptid) != 0)
 342     xsnprintf (buf, sizeof (buf), "Thread %d.0x%lx",
 343                ptid_get_pid (ptid), ptid_get_tid (ptid));
 344   else if (ptid_get_lwp (ptid) != 0)
 345     xsnprintf (buf, sizeof (buf), "LWP %d.%ld",
 346                ptid_get_pid (ptid), ptid_get_lwp (ptid));
 347   else
 348     xsnprintf (buf, sizeof (buf), "Process %d",
 349                ptid_get_pid (ptid));
 350
 351   return buf;
 352 }
 353
 354 int
 355 kill_inferior (int pid)
 356 {
 357   gdb_agent_about_to_close (pid);
 358
 359   return (*the_target->kill) (pid);
 360 }
 361
 362 /* Target can do hardware single step.  */
 363
 364 int
 365 target_can_do_hardware_single_step (void)
 366 {
 367   return 1;
 368 }
 369
 370 /* Default implementation for breakpoint_kind_for_pc.
 371
 372    The default behavior for targets that don't implement breakpoint_kind_for_pc
 373    is to use the size of a breakpoint as the kind.  */
 374
 375 int
 376 default_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
 377 {
 378   int size = 0;
 379
 380   gdb_assert (the_target->sw_breakpoint_from_kind != NULL);
 381
 382   (*the_target->sw_breakpoint_from_kind) (0, &size);
 383   return size;
 384 }
 385
 386 /* Define it.  */
 387
 388 enum target_terminal::terminal_state target_terminal::terminal_state
 389   = target_terminal::terminal_is_ours;
 390
 391 /* See target/target.h.  */
 392
 393 void
 394 target_terminal::init ()
 395 {
 396   /* Placeholder needed because of fork_inferior.  Not necessary on
 397      GDBserver.  */
 398 }
 399
 400 /* See target/target.h.  */
 401
 402 void
 403 target_terminal::inferior ()
 404 {
 405   /* Placeholder needed because of fork_inferior.  Not necessary on
 406      GDBserver.  */
 407 }
 408
 409 /* See target/target.h.  */
 410
 411 void
 412 target_terminal::ours ()
 413 {
 414   /* Placeholder needed because of fork_inferior.  Not necessary on
 415      GDBserver.  */
 416 }
 417
 418 /* See target/target.h.  */
 419
 420 void
 421 target_terminal::ours_for_output (void)
 422 {
 423   /* Placeholder.  */
 424 }
 425
 426 /* See target/target.h.  */
 427
 428 void
 429 target_terminal::info (const char *arg, int from_tty)
 430 {
 431   /* Placeholder.  */
 432 }