gdb/gdbserver/target.c

   1 /* Target operations for the remote server for GDB.
   2    Copyright (C) 2002-2015 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 && thread_stopped (thread))
  72         s->stopped = thread;
  73
  74       if (s->first == NULL)
  75         s->first = thread;
  76
  77       if (s->current == NULL && ptid_equal (s->current_gen_ptid, entry->id))
  78         s->current = thread;
  79     }
  80
  81   return 0;
  82 }
  83
  84 /* The thread that was current before prepare_to_access_memory was
  85    called.  done_accessing_memory uses this to restore the previous
  86    selected thread.  */
  87 static ptid_t prev_general_thread;
  88
  89 /* See target.h.  */
  90
  91 int
  92 prepare_to_access_memory (void)
  93 {
  94   struct thread_search search;
  95   struct thread_info *thread;
  96
  97   memset (&search, 0, sizeof (search));
  98   search.current_gen_ptid = general_thread;
  99   prev_general_thread = general_thread;
 100
 101   if (the_target->prepare_to_access_memory != NULL)
 102     {
 103       int res;
 104
 105       res = the_target->prepare_to_access_memory ();
 106       if (res != 0)
 107         return res;
 108     }
 109
 110   find_inferior (&all_threads, thread_search_callback, &search);
 111
 112   /* Prefer a stopped thread.  If none is found, try the current
 113      thread.  Otherwise, take the first thread in the process.  If
 114      none is found, undo the effects of
 115      target->prepare_to_access_memory() and return error.  */
 116   if (search.stopped != NULL)
 117     thread = search.stopped;
 118   else if (search.current != NULL)
 119     thread = search.current;
 120   else if (search.first != NULL)
 121     thread = search.first;
 122   else
 123     {
 124       done_accessing_memory ();
 125       return 1;
 126     }
 127
 128   current_thread = thread;
 129   general_thread = ptid_of (thread);
 130
 131   return 0;
 132 }
 133
 134 /* See target.h.  */
 135
 136 void
 137 done_accessing_memory (void)
 138 {
 139   if (the_target->done_accessing_memory != NULL)
 140     the_target->done_accessing_memory ();
 141
 142   /* Restore the previous selected thread.  */
 143   general_thread = prev_general_thread;
 144   current_thread = find_thread_ptid (general_thread);
 145 }
 146
 147 int
 148 read_inferior_memory (CORE_ADDR memaddr, unsigned char *myaddr, int len)
 149 {
 150   int res;
 151   res = (*the_target->read_memory) (memaddr, myaddr, len);
 152   check_mem_read (memaddr, myaddr, len);
 153   return res;
 154 }
 155
 156 /* See target/target.h.  */
 157
 158 int
 159 target_read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
 160 {
 161   return read_inferior_memory (memaddr, myaddr, len);
 162 }
 163
 164 /* See target/target.h.  */
 165
 166 int
 167 target_read_uint32 (CORE_ADDR memaddr, uint32_t *result)
 168 {
 169   return read_inferior_memory (memaddr, (gdb_byte *) result, sizeof (*result));
 170 }
 171
 172 int
 173 write_inferior_memory (CORE_ADDR memaddr, const unsigned char *myaddr,
 174                        int len)
 175 {
 176   /* Lacking cleanups, there is some potential for a memory leak if the
 177      write fails and we go through error().  Make sure that no more than
 178      one buffer is ever pending by making BUFFER static.  */
 179   static unsigned char *buffer = 0;
 180   int res;
 181
 182   if (buffer != NULL)
 183     free (buffer);
 184
 185   buffer = (unsigned char *) xmalloc (len);
 186   memcpy (buffer, myaddr, len);
 187   check_mem_write (memaddr, buffer, myaddr, len);
 188   res = (*the_target->write_memory) (memaddr, buffer, len);
 189   free (buffer);
 190   buffer = NULL;
 191
 192   return res;
 193 }
 194
 195 /* See target/target.h.  */
 196
 197 int
 198 target_write_memory (CORE_ADDR memaddr, const gdb_byte *myaddr, ssize_t len)
 199 {
 200   return write_inferior_memory (memaddr, myaddr, len);
 201 }
 202
 203 ptid_t
 204 mywait (ptid_t ptid, struct target_waitstatus *ourstatus, int options,
 205         int connected_wait)
 206 {
 207   ptid_t ret;
 208
 209   if (connected_wait)
 210     server_waiting = 1;
 211
 212   ret = (*the_target->wait) (ptid, ourstatus, options);
 213
 214   /* We don't expose _LOADED events to gdbserver core.  See the
 215      `dlls_changed' global.  */
 216   if (ourstatus->kind == TARGET_WAITKIND_LOADED)
 217     ourstatus->kind = TARGET_WAITKIND_STOPPED;
 218
 219   /* If GDB is connected through TCP/serial, then GDBserver will most
 220      probably be running on its own terminal/console, so it's nice to
 221      print there why is GDBserver exiting.  If however, GDB is
 222      connected through stdio, then there's no need to spam the GDB
 223      console with this -- the user will already see the exit through
 224      regular GDB output, in that same terminal.  */
 225   if (!remote_connection_is_stdio ())
 226     {
 227       if (ourstatus->kind == TARGET_WAITKIND_EXITED)
 228         fprintf (stderr,
 229                  "\nChild exited with status %d\n", ourstatus->value.integer);
 230       else if (ourstatus->kind == TARGET_WAITKIND_SIGNALLED)
 231         fprintf (stderr, "\nChild terminated with signal = 0x%x (%s)\n",
 232                  gdb_signal_to_host (ourstatus->value.sig),
 233                  gdb_signal_to_name (ourstatus->value.sig));
 234     }
 235
 236   if (connected_wait)
 237     server_waiting = 0;
 238
 239   return ret;
 240 }
 241
 242 /* See target/target.h.  */
 243
 244 void
 245 target_stop_and_wait (ptid_t ptid)
 246 {
 247   struct target_waitstatus status;
 248   int was_non_stop = non_stop;
 249   struct thread_resume resume_info;
 250
 251   resume_info.thread = ptid;
 252   resume_info.kind = resume_stop;
 253   resume_info.sig = GDB_SIGNAL_0;
 254   (*the_target->resume) (&resume_info, 1);
 255
 256   non_stop = 1;
 257   mywait (ptid, &status, 0, 0);
 258   non_stop = was_non_stop;
 259 }
 260
 261 /* See target/target.h.  */
 262
 263 void
 264 target_continue_no_signal (ptid_t ptid)
 265 {
 266   struct thread_resume resume_info;
 267
 268   resume_info.thread = ptid;
 269   resume_info.kind = resume_continue;
 270   resume_info.sig = GDB_SIGNAL_0;
 271   (*the_target->resume) (&resume_info, 1);
 272 }
 273
 274 int
 275 start_non_stop (int nonstop)
 276 {
 277   if (the_target->start_non_stop == NULL)
 278     {
 279       if (nonstop)
 280         return -1;
 281       else
 282         return 0;
 283     }
 284
 285   return (*the_target->start_non_stop) (nonstop);
 286 }
 287
 288 void
 289 set_target_ops (struct target_ops *target)
 290 {
 291   the_target = XNEW (struct target_ops);
 292   memcpy (the_target, target, sizeof (*the_target));
 293 }
 294
 295 /* Convert pid to printable format.  */
 296
 297 const char *
 298 target_pid_to_str (ptid_t ptid)
 299 {
 300   static char buf[80];
 301
 302   if (ptid_equal (ptid, minus_one_ptid))
 303     xsnprintf (buf, sizeof (buf), "<all threads>");
 304   else if (ptid_equal (ptid, null_ptid))
 305     xsnprintf (buf, sizeof (buf), "<null thread>");
 306   else if (ptid_get_tid (ptid) != 0)
 307     xsnprintf (buf, sizeof (buf), "Thread %d.0x%lx",
 308                ptid_get_pid (ptid), ptid_get_tid (ptid));
 309   else if (ptid_get_lwp (ptid) != 0)
 310     xsnprintf (buf, sizeof (buf), "LWP %d.%ld",
 311                ptid_get_pid (ptid), ptid_get_lwp (ptid));
 312   else
 313     xsnprintf (buf, sizeof (buf), "Process %d",
 314                ptid_get_pid (ptid));
 315
 316   return buf;
 317 }
 318
 319 int
 320 kill_inferior (int pid)
 321 {
 322   gdb_agent_about_to_close (pid);
 323
 324   return (*the_target->kill) (pid);
 325 }
 326
 327 /* Target can do hardware single step.  */
 328
 329 int
 330 target_can_do_hardware_single_step (void)
 331 {
 332   return 1;
 333 }
 334
 335 /* Default implementation for breakpoint_kind_for_pc.
 336
 337    The default behavior for targets that don't implement breakpoint_kind_for_pc
 338    is to use the size of a breakpoint as the kind.  */
 339
 340 int
 341 default_breakpoint_kind_from_pc (CORE_ADDR *pcptr)
 342 {
 343   int size = 0;
 344
 345   gdb_assert (the_target->sw_breakpoint_from_kind != NULL);
 346
 347   (*the_target->sw_breakpoint_from_kind) (0, &size);
 348   return size;
 349 }