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   thread_info *found = find_thread_ptid (general_thread);
  30
  31   current_thread = found;
  32   return (current_thread != NULL);
  33 }
  34
  35 /* The thread that was current before prepare_to_access_memory was
  36    called.  done_accessing_memory uses this to restore the previous
  37    selected thread.  */
  38 static ptid_t prev_general_thread;
  39
  40 /* See target.h.  */
  41
  42 int
  43 prepare_to_access_memory (void)
  44 {
  45   /* The first thread found.  */
  46   struct thread_info *first = NULL;
  47   /* The first stopped thread found.  */
  48   struct thread_info *stopped = NULL;
  49   /* The current general thread, if found.  */
  50   struct thread_info *current = NULL;
  51
  52   /* Save the general thread value, since prepare_to_access_memory could change
  53      it.  */
  54   prev_general_thread = general_thread;
  55
  56   if (the_target->prepare_to_access_memory != NULL)
  57     {
  58       int res;
  59
  60       res = the_target->prepare_to_access_memory ();
  61       if (res != 0)
  62         return res;
  63     }
  64
  65   for_each_thread (prev_general_thread.pid (), [&] (thread_info *thread)
  66     {
  67       if (mythread_alive (thread->id))
  68         {
  69           if (stopped == NULL && the_target->thread_stopped != NULL
  70               && thread_stopped (thread))
  71             stopped = thread;
  72
  73           if (first == NULL)
  74             first = thread;
  75
  76           if (current == NULL && prev_general_thread == thread->id)
  77             current = thread;
  78         }
  79     });
  80
  81   /* The thread we end up choosing.  */
  82   struct thread_info *thread;
  83
  84   /* Prefer a stopped thread.  If none is found, try the current
  85      thread.  Otherwise, take the first thread in the process.  If
  86      none is found, undo the effects of
  87      target->prepare_to_access_memory() and return error.  */
  88   if (stopped != NULL)
  89     thread = stopped;
  90   else if (current != NULL)
  91     thread = current;
  92   else if (first != NULL)
  93     thread = first;
  94   else
  95     {
  96       done_accessing_memory ();
  97       return 1;
  98     }
  99
 100   current_thread = thread;
 101   general_thread = ptid_of (thread);
 102
 103   return 0;
 104 }
 105
 106 /* See target.h.  */
 107
 108 void
 109 done_accessing_memory (void)
 110 {
 111   if (the_target->done_accessing_memory != NULL)
 112     the_target->done_accessing_memory ();
 113
 114   /* Restore the previous selected thread.  */
 115   general_thread = prev_general_thread;
 116   switch_to_thread (general_thread);
 117 }
 118
 119 int
 120 read_inferior_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
 121 {
 122   int res;
 123   res = (*the_target->read_memory) (memaddr, myaddr, len);
 124   check_mem_read (memaddr, myaddr, len);
 125   return res;
 126 }
 127
 128 /* See target/target.h.  */
 129
 130 int
 131 target_read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
 132 {
 133   return read_inferior_memory (memaddr, myaddr, len);
 134 }
 135
 136 /* See target/target.h.  */
 137
 138 int
 139 target_read_uint32 (CORE_ADDR memaddr, uint32_t *result)
 140 {
 141   return read_inferior_memory (memaddr, (gdb_byte *) result, sizeof (*result));
 142 }
 143
 144 int
 145 write_inferior_memory (CORE_ADDR memaddr, const unsigned char *myaddr,
 146                        int len)
 147 {
 148   /* Lacking cleanups, there is some potential for a memory leak if the
 149      write fails and we go through error().  Make sure that no more than
 150      one buffer is ever pending by making BUFFER static.  */
 151   static unsigned char *buffer = 0;
 152   int res;
 153
 154   if (buffer != NULL)
 155     free (buffer);
 156
 157   buffer = (unsigned char *) xmalloc (len);
 158   memcpy (buffer, myaddr, len);
 159   check_mem_write (memaddr, buffer, myaddr, len);
 160   res = (*the_target->write_memory) (memaddr, buffer, len);
 161   free (buffer);
 162   buffer = NULL;
 163
 164   return res;
 165 }
 166
 167 /* See target/target.h.  */
 168
 169 int
 170 target_write_memory (CORE_ADDR memaddr, const gdb_byte *myaddr, ssize_t len)
 171 {
 172   return write_inferior_memory (memaddr, myaddr, len);
 173 }
 174
 175 ptid_t
 176 mywait (ptid_t ptid, struct target_waitstatus *ourstatus, int options,
 177         int connected_wait)
 178 {
 179   ptid_t ret;
 180
 181   if (connected_wait)
 182     server_waiting = 1;
 183
 184   ret = target_wait (ptid, ourstatus, options);
 185
 186   /* We don't expose _LOADED events to gdbserver core.  See the
 187      `dlls_changed' global.  */
 188   if (ourstatus->kind == TARGET_WAITKIND_LOADED)
 189     ourstatus->kind = TARGET_WAITKIND_STOPPED;
 190
 191   /* If GDB is connected through TCP/serial, then GDBserver will most
 192      probably be running on its own terminal/console, so it's nice to
 193      print there why is GDBserver exiting.  If however, GDB is
 194      connected through stdio, then there's no need to spam the GDB
 195      console with this -- the user will already see the exit through
 196      regular GDB output, in that same terminal.  */
 197   if (!remote_connection_is_stdio ())
 198     {
 199       if (ourstatus->kind == TARGET_WAITKIND_EXITED)
 200         fprintf (stderr,
 201                  "\nChild exited with status %d\n", ourstatus->value.integer);
 202       else if (ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
 203         fprintf (stderr, "\nChild terminated with signal = 0x%x (%s)\n",
 204                  gdb_signal_to_host (ourstatus->value.sig),
 205                  gdb_signal_to_name (ourstatus->value.sig));
 206     }
 207
 208   if (connected_wait)
 209     server_waiting = 0;
 210
 211   return ret;
 212 }
 213
 214 /* See target/target.h.  */
 215
 216 void
 217 target_stop_and_wait (ptid_t ptid)
 218 {
 219   struct target_waitstatus status;
 220   int was_non_stop = non_stop;
 221   struct thread_resume resume_info;
 222
 223   resume_info.thread = ptid;
 224   resume_info.kind = resume_stop;
 225   resume_info.sig = GDB_SIGNAL_0;
 226   (*the_target->resume) (&resume_info, 1);
 227
 228   non_stop = 1;
 229   mywait (ptid, &status, 0, 0);
 230   non_stop = was_non_stop;
 231 }
 232
 233 /* See target/target.h.  */
 234
 235 ptid_t
 236 target_wait (ptid_t ptid, struct target_waitstatus *status, int options)
 237 {
 238   return (*the_target->wait) (ptid, status, options);
 239 }
 240
 241 /* See target/target.h.  */
 242
 243 void
 244 target_mourn_inferior (ptid_t ptid)
 245 {
 246   (*the_target->mourn) (find_process_pid (ptid_get_pid (ptid)));
 247 }
 248
 249 /* See target/target.h.  */
 250
 251 void
 252 target_continue_no_signal (ptid_t ptid)
 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_0;
 259   (*the_target->resume) (&resume_info, 1);
 260 }
 261
 262 /* See target/target.h.  */
 263
 264 void
 265 target_continue (ptid_t ptid, enum gdb_signal signal)
 266 {
 267   struct thread_resume resume_info;
 268
 269   resume_info.thread = ptid;
 270   resume_info.kind = resume_continue;
 271   resume_info.sig = gdb_signal_to_host (signal);
 272   (*the_target->resume) (&resume_info, 1);
 273 }
 274
 275 /* See target/target.h.  */
 276
 277 int
 278 target_supports_multi_process (void)
 279 {
 280   return (the_target->supports_multi_process != NULL ?
 281           (*the_target->supports_multi_process) () : 0);
 282 }
 283
 284 int
 285 start_non_stop (int nonstop)
 286 {
 287   if (the_target->start_non_stop == NULL)
 288     {
 289       if (nonstop)
 290         return -1;
 291       else
 292         return 0;
 293     }
 294
 295   return (*the_target->start_non_stop) (nonstop);
 296 }
 297
 298 void
 299 set_target_ops (struct target_ops *target)
 300 {
 301   the_target = XNEW (struct target_ops);
 302   memcpy (the_target, target, sizeof (*the_target));
 303 }
 304
 305 /* Convert pid to printable format.  */
 306
 307 const char *
 308 target_pid_to_str (ptid_t ptid)
 309 {
 310   static char buf[80];
 311
 312   if (ptid_equal (ptid, minus_one_ptid))
 313     xsnprintf (buf, sizeof (buf), "<all threads>");
 314   else if (ptid_equal (ptid, null_ptid))
 315     xsnprintf (buf, sizeof (buf), "<null thread>");
 316   else if (ptid_get_tid (ptid) != 0)
 317     xsnprintf (buf, sizeof (buf), "Thread %d.0x%lx",
 318                ptid_get_pid (ptid), ptid_get_tid (ptid));
 319   else if (ptid_get_lwp (ptid) != 0)
 320     xsnprintf (buf, sizeof (buf), "LWP %d.%ld",
 321                ptid_get_pid (ptid), ptid_get_lwp (ptid));
 322   else
 323     xsnprintf (buf, sizeof (buf), "Process %d",
 324                ptid_get_pid (ptid));
 325
 326   return buf;
 327 }
 328
 329 int
 330 kill_inferior (int pid)
 331 {
 332   gdb_agent_about_to_close (pid);
 333
 334   return (*the_target->kill) (pid);
 335 }
 336
 337 /* Target can do hardware single step.  */
 338
 339 int
 340 target_can_do_hardware_single_step (void)
 341 {
 342   return 1;
 343 }
 344
 345 /* Default implementation for breakpoint_kind_for_pc.
 346
 347    The default behavior for targets that don't implement breakpoint_kind_for_pc
 348    is to use the size of a breakpoint as the kind.  */
 349
 350 int
 351 default_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
 352 {
 353   int size = 0;
 354
 355   gdb_assert (the_target->sw_breakpoint_from_kind != NULL);
 356
 357   (*the_target->sw_breakpoint_from_kind) (0, &size);
 358   return size;
 359 }
 360
 361 /* Define it.  */
 362
 363 target_terminal_state target_terminal::m_terminal_state
 364   = target_terminal_state::is_ours;
 365
 366 /* See target/target.h.  */
 367
 368 void
 369 target_terminal::init ()
 370 {
 371   /* Placeholder needed because of fork_inferior.  Not necessary on
 372      GDBserver.  */
 373 }
 374
 375 /* See target/target.h.  */
 376
 377 void
 378 target_terminal::inferior ()
 379 {
 380   /* Placeholder needed because of fork_inferior.  Not necessary on
 381      GDBserver.  */
 382 }
 383
 384 /* See target/target.h.  */
 385
 386 void
 387 target_terminal::ours ()
 388 {
 389   /* Placeholder needed because of fork_inferior.  Not necessary on
 390      GDBserver.  */
 391 }
 392
 393 /* See target/target.h.  */
 394
 395 void
 396 target_terminal::ours_for_output (void)
 397 {
 398   /* Placeholder.  */
 399 }
 400
 401 /* See target/target.h.  */
 402
 403 void
 404 target_terminal::info (const char *arg, int from_tty)
 405 {
 406   /* Placeholder.  */
 407 }