gdb/common/agent.c

   1 /* Shared utility routines for GDB to interact with agent.
   2
   3    Copyright (C) 2009-2014 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifdef GDBSERVER
  21 #include "server.h"
  22 #else
  23 #include "defs.h"
  24 #include "target.h"
  25 #include "inferior.h" /* for non_stop */
  26 #include "objfiles.h"
  27 #endif
  28
  29 #include <string.h>
  30 #include <unistd.h>
  31 #include "agent.h"
  32 #include "filestuff.h"
  33
  34 int debug_agent = 0;
  35
  36 #ifdef GDBSERVER
  37 #define DEBUG_AGENT(fmt, args...)       \
  38   if (debug_agent)                      \
  39     fprintf (stderr, fmt, ##args);
  40 #else
  41 #define DEBUG_AGENT(fmt, args...)       \
  42   if (debug_agent)                      \
  43     fprintf_unfiltered (gdb_stdlog, fmt, ##args);
  44 #endif
  45
  46 /* Global flag to determine using agent or not.  */
  47 int use_agent = 0;
  48
  49 /* Addresses of in-process agent's symbols both GDB and GDBserver cares
  50    about.  */
  51
  52 struct ipa_sym_addresses
  53 {
  54   CORE_ADDR addr_helper_thread_id;
  55   CORE_ADDR addr_cmd_buf;
  56   CORE_ADDR addr_capability;
  57 };
  58
  59 /* Cache of the helper thread id.  FIXME: this global should be made
  60    per-process.  */
  61 static unsigned int helper_thread_id = 0;
  62
  63 static struct
  64 {
  65   const char *name;
  66   int offset;
  67   int required;
  68 } symbol_list[] = {
  69   IPA_SYM(helper_thread_id),
  70   IPA_SYM(cmd_buf),
  71   IPA_SYM(capability),
  72 };
  73
  74 static struct ipa_sym_addresses ipa_sym_addrs;
  75
  76 static int all_agent_symbols_looked_up = 0;
  77
  78 int
  79 agent_loaded_p (void)
  80 {
  81   return all_agent_symbols_looked_up;
  82 }
  83
  84 /* Look up all symbols needed by agent.  Return 0 if all the symbols are
  85    found, return non-zero otherwise.  */
  86
  87 int
  88 agent_look_up_symbols (void *arg)
  89 {
  90   int i;
  91
  92   all_agent_symbols_looked_up = 0;
  93
  94   for (i = 0; i < sizeof (symbol_list) / sizeof (symbol_list[0]); i++)
  95     {
  96       CORE_ADDR *addrp =
  97         (CORE_ADDR *) ((char *) &ipa_sym_addrs + symbol_list[i].offset);
  98 #ifdef GDBSERVER
  99
 100       if (look_up_one_symbol (symbol_list[i].name, addrp, 1) == 0)
 101 #else
 102       struct bound_minimal_symbol sym =
 103         lookup_minimal_symbol (symbol_list[i].name, NULL,
 104                                (struct objfile *) arg);
 105
 106       if (sym.minsym != NULL)
 107         *addrp = BMSYMBOL_VALUE_ADDRESS (sym);
 108       else
 109 #endif
 110         {
 111           DEBUG_AGENT ("symbol `%s' not found\n", symbol_list[i].name);
 112           return -1;
 113         }
 114     }
 115
 116   all_agent_symbols_looked_up = 1;
 117   return 0;
 118 }
 119
 120 static unsigned int
 121 agent_get_helper_thread_id (void)
 122 {
 123   if  (helper_thread_id == 0)
 124     {
 125 #ifdef GDBSERVER
 126       if (read_inferior_memory (ipa_sym_addrs.addr_helper_thread_id,
 127                                 (unsigned char *) &helper_thread_id,
 128                                 sizeof helper_thread_id))
 129 #else
 130       enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 131       gdb_byte buf[4];
 132
 133       if (target_read_memory (ipa_sym_addrs.addr_helper_thread_id,
 134                               buf, sizeof buf) == 0)
 135         helper_thread_id = extract_unsigned_integer (buf, sizeof buf,
 136                                                      byte_order);
 137       else
 138 #endif
 139         {
 140           warning (_("Error reading helper thread's id in lib"));
 141         }
 142     }
 143
 144   return helper_thread_id;
 145 }
 146
 147 #ifdef HAVE_SYS_UN_H
 148 #include <sys/socket.h>
 149 #include <sys/un.h>
 150 #define SOCK_DIR P_tmpdir
 151
 152 #ifndef UNIX_PATH_MAX
 153 #define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
 154 #endif
 155
 156 #endif
 157
 158 /* Connects to synchronization socket.  PID is the pid of inferior, which is
 159    used to set up the connection socket.  */
 160
 161 static int
 162 gdb_connect_sync_socket (int pid)
 163 {
 164 #ifdef HAVE_SYS_UN_H
 165   struct sockaddr_un addr;
 166   int res, fd;
 167   char path[UNIX_PATH_MAX];
 168
 169   res = xsnprintf (path, UNIX_PATH_MAX, "%s/gdb_ust%d", P_tmpdir, pid);
 170   if (res >= UNIX_PATH_MAX)
 171     return -1;
 172
 173   res = fd = gdb_socket_cloexec (PF_UNIX, SOCK_STREAM, 0);
 174   if (res == -1)
 175     {
 176       warning (_("error opening sync socket: %s"), strerror (errno));
 177       return -1;
 178     }
 179
 180   addr.sun_family = AF_UNIX;
 181
 182   res = xsnprintf (addr.sun_path, UNIX_PATH_MAX, "%s", path);
 183   if (res >= UNIX_PATH_MAX)
 184     {
 185       warning (_("string overflow allocating socket name"));
 186       close (fd);
 187       return -1;
 188     }
 189
 190   res = connect (fd, (struct sockaddr *) &addr, sizeof (addr));
 191   if (res == -1)
 192     {
 193       warning (_("error connecting sync socket (%s): %s. "
 194                  "Make sure the directory exists and that it is writable."),
 195                  path, strerror (errno));
 196       close (fd);
 197       return -1;
 198     }
 199
 200   return fd;
 201 #else
 202   return -1;
 203 #endif
 204 }
 205
 206 /* Execute an agent command in the inferior.  PID is the value of pid of the
 207    inferior.  CMD is the buffer for command.  GDB or GDBserver will store the
 208    command into it and fetch the return result from CMD.  The interaction
 209    between GDB/GDBserver and the agent is synchronized by a synchronization
 210    socket.  Return zero if success, otherwise return non-zero.  */
 211
 212 int
 213 agent_run_command (int pid, const char *cmd, int len)
 214 {
 215   int fd;
 216   int tid = agent_get_helper_thread_id ();
 217   ptid_t ptid = ptid_build (pid, tid, 0);
 218
 219 #ifdef GDBSERVER
 220   int ret = write_inferior_memory (ipa_sym_addrs.addr_cmd_buf,
 221                                    (const unsigned char *) cmd, len);
 222 #else
 223   int ret = target_write_memory (ipa_sym_addrs.addr_cmd_buf,
 224                                  (gdb_byte *) cmd, len);
 225 #endif
 226
 227   if (ret != 0)
 228     {
 229       warning (_("unable to write"));
 230       return -1;
 231     }
 232
 233   DEBUG_AGENT ("agent: resumed helper thread\n");
 234
 235   /* Resume helper thread.  */
 236 #ifdef GDBSERVER
 237 {
 238   struct thread_resume resume_info;
 239
 240   resume_info.thread = ptid;
 241   resume_info.kind = resume_continue;
 242   resume_info.sig = GDB_SIGNAL_0;
 243   (*the_target->resume) (&resume_info, 1);
 244 }
 245 #else
 246  target_resume (ptid, 0, GDB_SIGNAL_0);
 247 #endif
 248
 249   fd = gdb_connect_sync_socket (pid);
 250   if (fd >= 0)
 251     {
 252       char buf[1] = "";
 253       int ret;
 254
 255       DEBUG_AGENT ("agent: signalling helper thread\n");
 256
 257       do
 258         {
 259           ret = write (fd, buf, 1);
 260         } while (ret == -1 && errno == EINTR);
 261
 262         DEBUG_AGENT ("agent: waiting for helper thread's response\n");
 263
 264       do
 265         {
 266           ret = read (fd, buf, 1);
 267         } while (ret == -1 && errno == EINTR);
 268
 269       close (fd);
 270
 271       DEBUG_AGENT ("agent: helper thread's response received\n");
 272     }
 273   else
 274     return -1;
 275
 276   /* Need to read response with the inferior stopped.  */
 277   if (!ptid_equal (ptid, null_ptid))
 278     {
 279       struct target_waitstatus status;
 280       int was_non_stop = non_stop;
 281       /* Stop thread PTID.  */
 282       DEBUG_AGENT ("agent: stop helper thread\n");
 283 #ifdef GDBSERVER
 284       {
 285         struct thread_resume resume_info;
 286
 287         resume_info.thread = ptid;
 288         resume_info.kind = resume_stop;
 289         resume_info.sig = GDB_SIGNAL_0;
 290         (*the_target->resume) (&resume_info, 1);
 291       }
 292
 293       non_stop = 1;
 294       mywait (ptid, &status, 0, 0);
 295 #else
 296       non_stop = 1;
 297       target_stop (ptid);
 298
 299       memset (&status, 0, sizeof (status));
 300       target_wait (ptid, &status, 0);
 301 #endif
 302       non_stop = was_non_stop;
 303     }
 304
 305   if (fd >= 0)
 306     {
 307 #ifdef GDBSERVER
 308       if (read_inferior_memory (ipa_sym_addrs.addr_cmd_buf,
 309                                 (unsigned char *) cmd, IPA_CMD_BUF_SIZE))
 310 #else
 311       if (target_read_memory (ipa_sym_addrs.addr_cmd_buf, (gdb_byte *) cmd,
 312                               IPA_CMD_BUF_SIZE))
 313 #endif
 314         {
 315           warning (_("Error reading command response"));
 316           return -1;
 317         }
 318     }
 319
 320   return 0;
 321 }
 322
 323 /* Each bit of it stands for a capability of agent.  */
 324 static unsigned int agent_capability = 0;
 325
 326 /* Return true if agent has capability AGENT_CAP, otherwise return false.  */
 327
 328 int
 329 agent_capability_check (enum agent_capa agent_capa)
 330 {
 331   if (agent_capability == 0)
 332     {
 333 #ifdef GDBSERVER
 334       if (read_inferior_memory (ipa_sym_addrs.addr_capability,
 335                                 (unsigned char *) &agent_capability,
 336                                 sizeof agent_capability))
 337 #else
 338       enum bfd_endian byte_order = gdbarch_byte_order (target_gdbarch ());
 339       gdb_byte buf[4];
 340
 341       if (target_read_memory (ipa_sym_addrs.addr_capability,
 342                               buf, sizeof buf) == 0)
 343         agent_capability = extract_unsigned_integer (buf, sizeof buf,
 344                                                      byte_order);
 345       else
 346 #endif
 347         warning (_("Error reading capability of agent"));
 348     }
 349   return agent_capability & agent_capa;
 350 }
 351
 352 /* Invalidate the cache of agent capability, so we'll read it from inferior
 353    again.  Call it when launches a new program or reconnect to remote stub.  */
 354
 355 void
 356 agent_capability_invalidate (void)
 357 {
 358   agent_capability = 0;
 359 }