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