gdb/gdbserver/target.c

   1 /* Target operations for the remote server for GDB.
   2    Copyright (C) 2002-2020 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 #include "gdbsupport/byte-vector.h"
  24
  25 process_stratum_target *the_target;
  26
  27 int
  28 set_desired_thread ()
  29 {
  30   client_state &cs = get_client_state ();
  31   thread_info *found = find_thread_ptid (cs.general_thread);
  32
  33   current_thread = found;
  34   return (current_thread != NULL);
  35 }
  36
  37 /* The thread that was current before prepare_to_access_memory was
  38    called.  done_accessing_memory uses this to restore the previous
  39    selected thread.  */
  40 static ptid_t prev_general_thread;
  41
  42 /* See target.h.  */
  43
  44 int
  45 prepare_to_access_memory (void)
  46 {
  47   client_state &cs = get_client_state ();
  48
  49   /* The first thread found.  */
  50   struct thread_info *first = NULL;
  51   /* The first stopped thread found.  */
  52   struct thread_info *stopped = NULL;
  53   /* The current general thread, if found.  */
  54   struct thread_info *current = NULL;
  55
  56   /* Save the general thread value, since prepare_to_access_memory could change
  57      it.  */
  58   prev_general_thread = cs.general_thread;
  59
  60   if (the_target->prepare_to_access_memory != NULL)
  61     {
  62       int res;
  63
  64       res = the_target->prepare_to_access_memory ();
  65       if (res != 0)
  66         return res;
  67     }
  68
  69   for_each_thread (prev_general_thread.pid (), [&] (thread_info *thread)
  70     {
  71       if (mythread_alive (thread->id))
  72         {
  73           if (stopped == NULL && the_target->thread_stopped != NULL
  74               && thread_stopped (thread))
  75             stopped = thread;
  76
  77           if (first == NULL)
  78             first = thread;
  79
  80           if (current == NULL && prev_general_thread == thread->id)
  81             current = thread;
  82         }
  83     });
  84
  85   /* The thread we end up choosing.  */
  86   struct thread_info *thread;
  87
  88   /* Prefer a stopped thread.  If none is found, try the current
  89      thread.  Otherwise, take the first thread in the process.  If
  90      none is found, undo the effects of
  91      target->prepare_to_access_memory() and return error.  */
  92   if (stopped != NULL)
  93     thread = stopped;
  94   else if (current != NULL)
  95     thread = current;
  96   else if (first != NULL)
  97     thread = first;
  98   else
  99     {
 100       done_accessing_memory ();
 101       return 1;
 102     }
 103
 104   current_thread = thread;
 105   cs.general_thread = ptid_of (thread);
 106
 107   return 0;
 108 }
 109
 110 /* See target.h.  */
 111
 112 void
 113 done_accessing_memory (void)
 114 {
 115   client_state &cs = get_client_state ();
 116
 117   if (the_target->done_accessing_memory != NULL)
 118     the_target->done_accessing_memory ();
 119
 120   /* Restore the previous selected thread.  */
 121   cs.general_thread = prev_general_thread;
 122   switch_to_thread (the_target, cs.general_thread);
 123 }
 124
 125 int
 126 read_inferior_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
 127 {
 128   int res;
 129   res = (*the_target->read_memory) (memaddr, myaddr, len);
 130   check_mem_read (memaddr, myaddr, len);
 131   return res;
 132 }
 133
 134 /* See target/target.h.  */
 135
 136 int
 137 target_read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
 138 {
 139   return read_inferior_memory (memaddr, myaddr, len);
 140 }
 141
 142 /* See target/target.h.  */
 143
 144 int
 145 target_read_uint32 (CORE_ADDR memaddr, uint32_t *result)
 146 {
 147   return read_inferior_memory (memaddr, (gdb_byte *) result, sizeof (*result));
 148 }
 149
 150 /* See target/target.h.  */
 151
 152 int
 153 target_write_memory (CORE_ADDR memaddr, const unsigned char *myaddr,
 154                      ssize_t len)
 155 {
 156   /* Make a copy of the data because check_mem_write may need to
 157      update it.  */
 158   gdb::byte_vector buffer (myaddr, myaddr + len);
 159   check_mem_write (memaddr, buffer.data (), myaddr, len);
 160   return (*the_target->write_memory) (memaddr, buffer.data (), len);
 161 }
 162
 163 ptid_t
 164 mywait (ptid_t ptid, struct target_waitstatus *ourstatus, int options,
 165         int connected_wait)
 166 {
 167   ptid_t ret;
 168
 169   if (connected_wait)
 170     server_waiting = 1;
 171
 172   ret = target_wait (ptid, ourstatus, options);
 173
 174   /* We don't expose _LOADED events to gdbserver core.  See the
 175      `dlls_changed' global.  */
 176   if (ourstatus->kind == TARGET_WAITKIND_LOADED)
 177     ourstatus->kind = TARGET_WAITKIND_STOPPED;
 178
 179   /* If GDB is connected through TCP/serial, then GDBserver will most
 180      probably be running on its own terminal/console, so it's nice to
 181      print there why is GDBserver exiting.  If however, GDB is
 182      connected through stdio, then there's no need to spam the GDB
 183      console with this -- the user will already see the exit through
 184      regular GDB output, in that same terminal.  */
 185   if (!remote_connection_is_stdio ())
 186     {
 187       if (ourstatus->kind == TARGET_WAITKIND_EXITED)
 188         fprintf (stderr,
 189                  "\nChild exited with status %d\n", ourstatus->value.integer);
 190       else if (ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
 191         fprintf (stderr, "\nChild terminated with signal = 0x%x (%s)\n",
 192                  gdb_signal_to_host (ourstatus->value.sig),
 193                  gdb_signal_to_name (ourstatus->value.sig));
 194     }
 195
 196   if (connected_wait)
 197     server_waiting = 0;
 198
 199   return ret;
 200 }
 201
 202 /* See target/target.h.  */
 203
 204 void
 205 target_stop_and_wait (ptid_t ptid)
 206 {
 207   struct target_waitstatus status;
 208   bool was_non_stop = non_stop;
 209   struct thread_resume resume_info;
 210
 211   resume_info.thread = ptid;
 212   resume_info.kind = resume_stop;
 213   resume_info.sig = GDB_SIGNAL_0;
 214   (*the_target->resume) (&resume_info, 1);
 215
 216   non_stop = true;
 217   mywait (ptid, &status, 0, 0);
 218   non_stop = was_non_stop;
 219 }
 220
 221 /* See target/target.h.  */
 222
 223 ptid_t
 224 target_wait (ptid_t ptid, struct target_waitstatus *status, int options)
 225 {
 226   return (*the_target->wait) (ptid, status, options);
 227 }
 228
 229 /* See target/target.h.  */
 230
 231 void
 232 target_mourn_inferior (ptid_t ptid)
 233 {
 234   (*the_target->mourn) (find_process_pid (ptid.pid ()));
 235 }
 236
 237 /* See target/target.h.  */
 238
 239 void
 240 target_continue_no_signal (ptid_t ptid)
 241 {
 242   struct thread_resume resume_info;
 243
 244   resume_info.thread = ptid;
 245   resume_info.kind = resume_continue;
 246   resume_info.sig = GDB_SIGNAL_0;
 247   (*the_target->resume) (&resume_info, 1);
 248 }
 249
 250 /* See target/target.h.  */
 251
 252 void
 253 target_continue (ptid_t ptid, enum gdb_signal signal)
 254 {
 255   struct thread_resume resume_info;
 256
 257   resume_info.thread = ptid;
 258   resume_info.kind = resume_continue;
 259   resume_info.sig = gdb_signal_to_host (signal);
 260   (*the_target->resume) (&resume_info, 1);
 261 }
 262
 263 /* See target/target.h.  */
 264
 265 int
 266 target_supports_multi_process (void)
 267 {
 268   return (the_target->supports_multi_process != NULL ?
 269           (*the_target->supports_multi_process) () : 0);
 270 }
 271
 272 int
 273 start_non_stop (int nonstop)
 274 {
 275   if (the_target->start_non_stop == NULL)
 276     {
 277       if (nonstop)
 278         return -1;
 279       else
 280         return 0;
 281     }
 282
 283   return (*the_target->start_non_stop) (nonstop);
 284 }
 285
 286 void
 287 set_target_ops (process_stratum_target *target)
 288 {
 289   the_target = XNEW (process_stratum_target);
 290   memcpy (the_target, target, sizeof (*the_target));
 291 }
 292
 293 /* Convert pid to printable format.  */
 294
 295 const char *
 296 target_pid_to_str (ptid_t ptid)
 297 {
 298   static char buf[80];
 299
 300   if (ptid == minus_one_ptid)
 301     xsnprintf (buf, sizeof (buf), "<all threads>");
 302   else if (ptid == null_ptid)
 303     xsnprintf (buf, sizeof (buf), "<null thread>");
 304   else if (ptid.tid () != 0)
 305     xsnprintf (buf, sizeof (buf), "Thread %d.0x%lx",
 306                ptid.pid (), ptid.tid ());
 307   else if (ptid.lwp () != 0)
 308     xsnprintf (buf, sizeof (buf), "LWP %d.%ld",
 309                ptid.pid (), ptid.lwp ());
 310   else
 311     xsnprintf (buf, sizeof (buf), "Process %d",
 312                ptid.pid ());
 313
 314   return buf;
 315 }
 316
 317 int
 318 kill_inferior (process_info *proc)
 319 {
 320   gdb_agent_about_to_close (proc->pid);
 321
 322   return (*the_target->kill) (proc);
 323 }
 324
 325 /* Target can do hardware single step.  */
 326
 327 int
 328 target_can_do_hardware_single_step (void)
 329 {
 330   return 1;
 331 }
 332
 333 /* Default implementation for breakpoint_kind_for_pc.
 334
 335    The default behavior for targets that don't implement breakpoint_kind_for_pc
 336    is to use the size of a breakpoint as the kind.  */
 337
 338 int
 339 default_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
 340 {
 341   int size = 0;
 342
 343   gdb_assert (the_target->sw_breakpoint_from_kind != NULL);
 344
 345   (*the_target->sw_breakpoint_from_kind) (0, &size);
 346   return size;
 347 }
 348
 349 /* Define it.  */
 350
 351 target_terminal_state target_terminal::m_terminal_state
 352   = target_terminal_state::is_ours;
 353
 354 /* See target/target.h.  */
 355
 356 void
 357 target_terminal::init ()
 358 {
 359   /* Placeholder needed because of fork_inferior.  Not necessary on
 360      GDBserver.  */
 361 }
 362
 363 /* See target/target.h.  */
 364
 365 void
 366 target_terminal::inferior ()
 367 {
 368   /* Placeholder needed because of fork_inferior.  Not necessary on
 369      GDBserver.  */
 370 }
 371
 372 /* See target/target.h.  */
 373
 374 void
 375 target_terminal::ours ()
 376 {
 377   /* Placeholder needed because of fork_inferior.  Not necessary on
 378      GDBserver.  */
 379 }
 380
 381 /* See target/target.h.  */
 382
 383 void
 384 target_terminal::ours_for_output (void)
 385 {
 386   /* Placeholder.  */
 387 }
 388
 389 /* See target/target.h.  */
 390
 391 void
 392 target_terminal::info (const char *arg, int from_tty)
 393 {
 394   /* Placeholder.  */
 395 }