gdb/gdbserver/target.c

   1 /* Target operations for the remote server for GDB.
   2    Copyright (C) 2002-2018 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 int
 150 write_inferior_memory (CORE_ADDR memaddr, const unsigned char *myaddr,
 151                        int len)
 152 {
 153   /* Lacking cleanups, there is some potential for a memory leak if the
 154      write fails and we go through error().  Make sure that no more than
 155      one buffer is ever pending by making BUFFER static.  */
 156   static unsigned char *buffer = 0;
 157   int res;
 158
 159   if (buffer != NULL)
 160     free (buffer);
 161
 162   buffer = (unsigned char *) xmalloc (len);
 163   memcpy (buffer, myaddr, len);
 164   check_mem_write (memaddr, buffer, myaddr, len);
 165   res = (*the_target->write_memory) (memaddr, buffer, len);
 166   free (buffer);
 167   buffer = NULL;
 168
 169   return res;
 170 }
 171
 172 /* See target/target.h.  */
 173
 174 int
 175 target_write_memory (CORE_ADDR memaddr, const gdb_byte *myaddr, ssize_t len)
 176 {
 177   return write_inferior_memory (memaddr, myaddr, len);
 178 }
 179
 180 ptid_t
 181 mywait (ptid_t ptid, struct target_waitstatus *ourstatus, int options,
 182         int connected_wait)
 183 {
 184   ptid_t ret;
 185
 186   if (connected_wait)
 187     server_waiting = 1;
 188
 189   ret = target_wait (ptid, ourstatus, options);
 190
 191   /* We don't expose _LOADED events to gdbserver core.  See the
 192      `dlls_changed' global.  */
 193   if (ourstatus->kind == TARGET_WAITKIND_LOADED)
 194     ourstatus->kind = TARGET_WAITKIND_STOPPED;
 195
 196   /* If GDB is connected through TCP/serial, then GDBserver will most
 197      probably be running on its own terminal/console, so it's nice to
 198      print there why is GDBserver exiting.  If however, GDB is
 199      connected through stdio, then there's no need to spam the GDB
 200      console with this -- the user will already see the exit through
 201      regular GDB output, in that same terminal.  */
 202   if (!remote_connection_is_stdio ())
 203     {
 204       if (ourstatus->kind == TARGET_WAITKIND_EXITED)
 205         fprintf (stderr,
 206                  "\nChild exited with status %d\n", ourstatus->value.integer);
 207       else if (ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
 208         fprintf (stderr, "\nChild terminated with signal = 0x%x (%s)\n",
 209                  gdb_signal_to_host (ourstatus->value.sig),
 210                  gdb_signal_to_name (ourstatus->value.sig));
 211     }
 212
 213   if (connected_wait)
 214     server_waiting = 0;
 215
 216   return ret;
 217 }
 218
 219 /* See target/target.h.  */
 220
 221 void
 222 target_stop_and_wait (ptid_t ptid)
 223 {
 224   struct target_waitstatus status;
 225   int was_non_stop = non_stop;
 226   struct thread_resume resume_info;
 227
 228   resume_info.thread = ptid;
 229   resume_info.kind = resume_stop;
 230   resume_info.sig = GDB_SIGNAL_0;
 231   (*the_target->resume) (&resume_info, 1);
 232
 233   non_stop = 1;
 234   mywait (ptid, &status, 0, 0);
 235   non_stop = was_non_stop;
 236 }
 237
 238 /* See target/target.h.  */
 239
 240 ptid_t
 241 target_wait (ptid_t ptid, struct target_waitstatus *status, int options)
 242 {
 243   return (*the_target->wait) (ptid, status, options);
 244 }
 245
 246 /* See target/target.h.  */
 247
 248 void
 249 target_mourn_inferior (ptid_t ptid)
 250 {
 251   (*the_target->mourn) (find_process_pid (ptid.pid ()));
 252 }
 253
 254 /* See target/target.h.  */
 255
 256 void
 257 target_continue_no_signal (ptid_t ptid)
 258 {
 259   struct thread_resume resume_info;
 260
 261   resume_info.thread = ptid;
 262   resume_info.kind = resume_continue;
 263   resume_info.sig = GDB_SIGNAL_0;
 264   (*the_target->resume) (&resume_info, 1);
 265 }
 266
 267 /* See target/target.h.  */
 268
 269 void
 270 target_continue (ptid_t ptid, enum gdb_signal signal)
 271 {
 272   struct thread_resume resume_info;
 273
 274   resume_info.thread = ptid;
 275   resume_info.kind = resume_continue;
 276   resume_info.sig = gdb_signal_to_host (signal);
 277   (*the_target->resume) (&resume_info, 1);
 278 }
 279
 280 /* See target/target.h.  */
 281
 282 int
 283 target_supports_multi_process (void)
 284 {
 285   return (the_target->supports_multi_process != NULL ?
 286           (*the_target->supports_multi_process) () : 0);
 287 }
 288
 289 int
 290 start_non_stop (int nonstop)
 291 {
 292   if (the_target->start_non_stop == NULL)
 293     {
 294       if (nonstop)
 295         return -1;
 296       else
 297         return 0;
 298     }
 299
 300   return (*the_target->start_non_stop) (nonstop);
 301 }
 302
 303 void
 304 set_target_ops (struct target_ops *target)
 305 {
 306   the_target = XNEW (struct target_ops);
 307   memcpy (the_target, target, sizeof (*the_target));
 308 }
 309
 310 /* Convert pid to printable format.  */
 311
 312 const char *
 313 target_pid_to_str (ptid_t ptid)
 314 {
 315   static char buf[80];
 316
 317   if (ptid_equal (ptid, minus_one_ptid))
 318     xsnprintf (buf, sizeof (buf), "<all threads>");
 319   else if (ptid_equal (ptid, null_ptid))
 320     xsnprintf (buf, sizeof (buf), "<null thread>");
 321   else if (ptid_get_tid (ptid) != 0)
 322     xsnprintf (buf, sizeof (buf), "Thread %d.0x%lx",
 323                ptid.pid (), ptid_get_tid (ptid));
 324   else if (ptid_get_lwp (ptid) != 0)
 325     xsnprintf (buf, sizeof (buf), "LWP %d.%ld",
 326                ptid.pid (), ptid_get_lwp (ptid));
 327   else
 328     xsnprintf (buf, sizeof (buf), "Process %d",
 329                ptid.pid ());
 330
 331   return buf;
 332 }
 333
 334 int
 335 kill_inferior (int pid)
 336 {
 337   gdb_agent_about_to_close (pid);
 338
 339   return (*the_target->kill) (pid);
 340 }
 341
 342 /* Target can do hardware single step.  */
 343
 344 int
 345 target_can_do_hardware_single_step (void)
 346 {
 347   return 1;
 348 }
 349
 350 /* Default implementation for breakpoint_kind_for_pc.
 351
 352    The default behavior for targets that don't implement breakpoint_kind_for_pc
 353    is to use the size of a breakpoint as the kind.  */
 354
 355 int
 356 default_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
 357 {
 358   int size = 0;
 359
 360   gdb_assert (the_target->sw_breakpoint_from_kind != NULL);
 361
 362   (*the_target->sw_breakpoint_from_kind) (0, &size);
 363   return size;
 364 }
 365
 366 /* Define it.  */
 367
 368 target_terminal_state target_terminal::m_terminal_state
 369   = target_terminal_state::is_ours;
 370
 371 /* See target/target.h.  */
 372
 373 void
 374 target_terminal::init ()
 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::inferior ()
 384 {
 385   /* Placeholder needed because of fork_inferior.  Not necessary on
 386      GDBserver.  */
 387 }
 388
 389 /* See target/target.h.  */
 390
 391 void
 392 target_terminal::ours ()
 393 {
 394   /* Placeholder needed because of fork_inferior.  Not necessary on
 395      GDBserver.  */
 396 }
 397
 398 /* See target/target.h.  */
 399
 400 void
 401 target_terminal::ours_for_output (void)
 402 {
 403   /* Placeholder.  */
 404 }
 405
 406 /* See target/target.h.  */
 407
 408 void
 409 target_terminal::info (const char *arg, int from_tty)
 410 {
 411   /* Placeholder.  */
 412 }