gdb/gdbserver/target.c

   1 /* Target operations for the remote server for GDB.
   2    Copyright (C) 2002-2019 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   client_state &cs = get_client_state ();
  30   thread_info *found = find_thread_ptid (cs.general_thread);
  31
  32   current_thread = found;
  33   return (current_thread != NULL);
  34 }
  35
  36 /* The thread that was current before prepare_to_access_memory was
  37    called.  done_accessing_memory uses this to restore the previous
  38    selected thread.  */
  39 static ptid_t prev_general_thread;
  40
  41 /* See target.h.  */
  42
  43 int
  44 prepare_to_access_memory (void)
  45 {
  46   client_state &cs = get_client_state ();
  47
  48   /* The first thread found.  */
  49   struct thread_info *first = NULL;
  50   /* The first stopped thread found.  */
  51   struct thread_info *stopped = NULL;
  52   /* The current general thread, if found.  */
  53   struct thread_info *current = NULL;
  54
  55   /* Save the general thread value, since prepare_to_access_memory could change
  56      it.  */
  57   prev_general_thread = cs.general_thread;
  58
  59   if (the_target->prepare_to_access_memory != NULL)
  60     {
  61       int res;
  62
  63       res = the_target->prepare_to_access_memory ();
  64       if (res != 0)
  65         return res;
  66     }
  67
  68   for_each_thread (prev_general_thread.pid (), [&] (thread_info *thread)
  69     {
  70       if (mythread_alive (thread->id))
  71         {
  72           if (stopped == NULL && the_target->thread_stopped != NULL
  73               && thread_stopped (thread))
  74             stopped = thread;
  75
  76           if (first == NULL)
  77             first = thread;
  78
  79           if (current == NULL && prev_general_thread == thread->id)
  80             current = thread;
  81         }
  82     });
  83
  84   /* The thread we end up choosing.  */
  85   struct thread_info *thread;
  86
  87   /* Prefer a stopped thread.  If none is found, try the current
  88      thread.  Otherwise, take the first thread in the process.  If
  89      none is found, undo the effects of
  90      target->prepare_to_access_memory() and return error.  */
  91   if (stopped != NULL)
  92     thread = stopped;
  93   else if (current != NULL)
  94     thread = current;
  95   else if (first != NULL)
  96     thread = first;
  97   else
  98     {
  99       done_accessing_memory ();
 100       return 1;
 101     }
 102
 103   current_thread = thread;
 104   cs.general_thread = ptid_of (thread);
 105
 106   return 0;
 107 }
 108
 109 /* See target.h.  */
 110
 111 void
 112 done_accessing_memory (void)
 113 {
 114   client_state &cs = get_client_state ();
 115
 116   if (the_target->done_accessing_memory != NULL)
 117     the_target->done_accessing_memory ();
 118
 119   /* Restore the previous selected thread.  */
 120   cs.general_thread = prev_general_thread;
 121   switch_to_thread (cs.general_thread);
 122 }
 123
 124 int
 125 read_inferior_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
 126 {
 127   int res;
 128   res = (*the_target->read_memory) (memaddr, myaddr, len);
 129   check_mem_read (memaddr, myaddr, len);
 130   return res;
 131 }
 132
 133 /* See target/target.h.  */
 134
 135 int
 136 target_read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
 137 {
 138   return read_inferior_memory (memaddr, myaddr, len);
 139 }
 140
 141 /* See target/target.h.  */
 142
 143 int
 144 target_read_uint32 (CORE_ADDR memaddr, uint32_t *result)
 145 {
 146   return read_inferior_memory (memaddr, (gdb_byte *) result, sizeof (*result));
 147 }
 148
 149 /* See target/target.h.  */
 150
 151 int
 152 target_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr,
 153                      ssize_t len)
 154 {
 155   /* Make a copy of the data because check_mem_write may need to
 156      update it.  */
 157   std::vector<unsigned char> buffer (myaddr, myaddr + len);
 158   check_mem_write (memaddr, buffer.data (), myaddr, len);
 159   return (*the_target->write_memory) (memaddr, buffer.data (), len);
 160 }
 161
 162 ptid_t
 163 mywait (ptid_t ptid, struct target_waitstatus *ourstatus, int options,
 164         int connected_wait)
 165 {
 166   ptid_t ret;
 167
 168   if (connected_wait)
 169     server_waiting = 1;
 170
 171   ret = target_wait (ptid, ourstatus, options);
 172
 173   /* We don't expose _LOADED events to gdbserver core.  See the
 174      `dlls_changed' global.  */
 175   if (ourstatus->kind == TARGET_WAITKIND_LOADED)
 176     ourstatus->kind = TARGET_WAITKIND_STOPPED;
 177
 178   /* If GDB is connected through TCP/serial, then GDBserver will most
 179      probably be running on its own terminal/console, so it's nice to
 180      print there why is GDBserver exiting.  If however, GDB is
 181      connected through stdio, then there's no need to spam the GDB
 182      console with this -- the user will already see the exit through
 183      regular GDB output, in that same terminal.  */
 184   if (!remote_connection_is_stdio ())
 185     {
 186       if (ourstatus->kind == TARGET_WAITKIND_EXITED)
 187         fprintf (stderr,
 188                  "\nChild exited with status %d\n", ourstatus->value.integer);
 189       else if (ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
 190         fprintf (stderr, "\nChild terminated with signal = 0x%x (%s)\n",
 191                  gdb_signal_to_host (ourstatus->value.sig),
 192                  gdb_signal_to_name (ourstatus->value.sig));
 193     }
 194
 195   if (connected_wait)
 196     server_waiting = 0;
 197
 198   return ret;
 199 }
 200
 201 /* See target/target.h.  */
 202
 203 void
 204 target_stop_and_wait (ptid_t ptid)
 205 {
 206   struct target_waitstatus status;
 207   int was_non_stop = non_stop;
 208   struct thread_resume resume_info;
 209
 210   resume_info.thread = ptid;
 211   resume_info.kind = resume_stop;
 212   resume_info.sig = GDB_SIGNAL_0;
 213   (*the_target->resume) (&resume_info, 1);
 214
 215   non_stop = 1;
 216   mywait (ptid, &status, 0, 0);
 217   non_stop = was_non_stop;
 218 }
 219
 220 /* See target/target.h.  */
 221
 222 ptid_t
 223 target_wait (ptid_t ptid, struct target_waitstatus *status, int options)
 224 {
 225   return (*the_target->wait) (ptid, status, options);
 226 }
 227
 228 /* See target/target.h.  */
 229
 230 void
 231 target_mourn_inferior (ptid_t ptid)
 232 {
 233   (*the_target->mourn) (find_process_pid (ptid.pid ()));
 234 }
 235
 236 /* See target/target.h.  */
 237
 238 void
 239 target_continue_no_signal (ptid_t ptid)
 240 {
 241   struct thread_resume resume_info;
 242
 243   resume_info.thread = ptid;
 244   resume_info.kind = resume_continue;
 245   resume_info.sig = GDB_SIGNAL_0;
 246   (*the_target->resume) (&resume_info, 1);
 247 }
 248
 249 /* See target/target.h.  */
 250
 251 void
 252 target_continue (ptid_t ptid, enum gdb_signal signal)
 253 {
 254   struct thread_resume resume_info;
 255
 256   resume_info.thread = ptid;
 257   resume_info.kind = resume_continue;
 258   resume_info.sig = gdb_signal_to_host (signal);
 259   (*the_target->resume) (&resume_info, 1);
 260 }
 261
 262 /* See target/target.h.  */
 263
 264 int
 265 target_supports_multi_process (void)
 266 {
 267   return (the_target->supports_multi_process != NULL ?
 268           (*the_target->supports_multi_process) () : 0);
 269 }
 270
 271 int
 272 start_non_stop (int nonstop)
 273 {
 274   if (the_target->start_non_stop == NULL)
 275     {
 276       if (nonstop)
 277         return -1;
 278       else
 279         return 0;
 280     }
 281
 282   return (*the_target->start_non_stop) (nonstop);
 283 }
 284
 285 void
 286 set_target_ops (struct target_ops *target)
 287 {
 288   the_target = XNEW (struct target_ops);
 289   memcpy (the_target, target, sizeof (*the_target));
 290 }
 291
 292 /* Convert pid to printable format.  */
 293
 294 const char *
 295 target_pid_to_str (ptid_t ptid)
 296 {
 297   static char buf[80];
 298
 299   if (ptid == minus_one_ptid)
 300     xsnprintf (buf, sizeof (buf), "<all threads>");
 301   else if (ptid == null_ptid)
 302     xsnprintf (buf, sizeof (buf), "<null thread>");
 303   else if (ptid.tid () != 0)
 304     xsnprintf (buf, sizeof (buf), "Thread %d.0x%lx",
 305                ptid.pid (), ptid.tid ());
 306   else if (ptid.lwp () != 0)
 307     xsnprintf (buf, sizeof (buf), "LWP %d.%ld",
 308                ptid.pid (), ptid.lwp ());
 309   else
 310     xsnprintf (buf, sizeof (buf), "Process %d",
 311                ptid.pid ());
 312
 313   return buf;
 314 }
 315
 316 int
 317 kill_inferior (process_info *proc)
 318 {
 319   gdb_agent_about_to_close (proc->pid);
 320
 321   return (*the_target->kill) (proc);
 322 }
 323
 324 /* Target can do hardware single step.  */
 325
 326 int
 327 target_can_do_hardware_single_step (void)
 328 {
 329   return 1;
 330 }
 331
 332 /* Default implementation for breakpoint_kind_for_pc.
 333
 334    The default behavior for targets that don't implement breakpoint_kind_for_pc
 335    is to use the size of a breakpoint as the kind.  */
 336
 337 int
 338 default_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
 339 {
 340   int size = 0;
 341
 342   gdb_assert (the_target->sw_breakpoint_from_kind != NULL);
 343
 344   (*the_target->sw_breakpoint_from_kind) (0, &size);
 345   return size;
 346 }
 347
 348 /* Define it.  */
 349
 350 target_terminal_state target_terminal::m_terminal_state
 351   = target_terminal_state::is_ours;
 352
 353 /* See target/target.h.  */
 354
 355 void
 356 target_terminal::init ()
 357 {
 358   /* Placeholder needed because of fork_inferior.  Not necessary on
 359      GDBserver.  */
 360 }
 361
 362 /* See target/target.h.  */
 363
 364 void
 365 target_terminal::inferior ()
 366 {
 367   /* Placeholder needed because of fork_inferior.  Not necessary on
 368      GDBserver.  */
 369 }
 370
 371 /* See target/target.h.  */
 372
 373 void
 374 target_terminal::ours ()
 375 {
 376   /* Placeholder needed because of fork_inferior.  Not necessary on
 377      GDBserver.  */
 378 }
 379
 380 /* See target/target.h.  */
 381
 382 void
 383 target_terminal::ours_for_output (void)
 384 {
 385   /* Placeholder.  */
 386 }
 387
 388 /* See target/target.h.  */
 389
 390 void
 391 target_terminal::info (const char *arg, int from_tty)
 392 {
 393   /* Placeholder.  */
 394 }