gdbsupport/agent.cc

   1 /* Shared utility routines for GDB to interact with agent.
   2
   3    Copyright (C) 2009-2020 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 #include "common-defs.h"
  21 #include "target/target.h"
  22 #include "gdbsupport/symbol.h"
  23 #include <unistd.h>
  24 #include "filestuff.h"
  25
  26 #define IPA_SYM_STRUCT_NAME ipa_sym_addresses_common
  27 #include "agent.h"
  28
  29 bool debug_agent = false;
  30
  31 /* A stdarg wrapper for debug_vprintf.  */
  32
  33 static void ATTRIBUTE_PRINTF (1, 2)
  34 debug_agent_printf (const char *fmt, ...)
  35 {
  36   va_list ap;
  37
  38   if (!debug_agent)
  39     return;
  40   va_start (ap, fmt);
  41   debug_vprintf (fmt, ap);
  42   va_end (ap);
  43 }
  44
  45 #define DEBUG_AGENT debug_agent_printf
  46
  47 /* Global flag to determine using agent or not.  */
  48 bool use_agent = false;
  49
  50 /* Addresses of in-process agent's symbols both GDB and GDBserver cares
  51    about.  */
  52
  53 struct ipa_sym_addresses_common
  54 {
  55   CORE_ADDR addr_helper_thread_id;
  56   CORE_ADDR addr_cmd_buf;
  57   CORE_ADDR addr_capability;
  58 };
  59
  60 /* Cache of the helper thread id.  FIXME: this global should be made
  61    per-process.  */
  62 static uint32_t helper_thread_id = 0;
  63
  64 static struct
  65 {
  66   const char *name;
  67   int offset;
  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_common ipa_sym_addrs;
  75
  76 static bool all_agent_symbols_looked_up = false;
  77
  78 bool
  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   all_agent_symbols_looked_up = false;
  91
  92   for (int i = 0; i < sizeof (symbol_list) / sizeof (symbol_list[0]); i++)
  93     {
  94       CORE_ADDR *addrp =
  95         (CORE_ADDR *) ((char *) &ipa_sym_addrs + symbol_list[i].offset);
  96       struct objfile *objfile = (struct objfile *) arg;
  97
  98       if (find_minimal_symbol_address (symbol_list[i].name, addrp,
  99                                        objfile) != 0)
 100         {
 101           DEBUG_AGENT ("symbol `%s' not found\n", symbol_list[i].name);
 102           return -1;
 103         }
 104     }
 105
 106   all_agent_symbols_looked_up = true;
 107   return 0;
 108 }
 109
 110 static unsigned int
 111 agent_get_helper_thread_id (void)
 112 {
 113   if  (helper_thread_id == 0)
 114     {
 115       if (target_read_uint32 (ipa_sym_addrs.addr_helper_thread_id,
 116                               &helper_thread_id))
 117         warning (_("Error reading helper thread's id in lib"));
 118     }
 119
 120   return helper_thread_id;
 121 }
 122
 123 #ifdef HAVE_SYS_UN_H
 124 #include <sys/socket.h>
 125 #include <sys/un.h>
 126 #define SOCK_DIR P_tmpdir
 127
 128 #ifndef UNIX_PATH_MAX
 129 #define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
 130 #endif
 131
 132 #endif
 133
 134 /* Connects to synchronization socket.  PID is the pid of inferior, which is
 135    used to set up the connection socket.  */
 136
 137 static int
 138 gdb_connect_sync_socket (int pid)
 139 {
 140 #ifdef HAVE_SYS_UN_H
 141   struct sockaddr_un addr;
 142   int res, fd;
 143   char path[UNIX_PATH_MAX];
 144
 145   res = xsnprintf (path, UNIX_PATH_MAX, "%s/gdb_ust%d", P_tmpdir, pid);
 146   if (res >= UNIX_PATH_MAX)
 147     return -1;
 148
 149   res = fd = gdb_socket_cloexec (PF_UNIX, SOCK_STREAM, 0);
 150   if (res == -1)
 151     {
 152       warning (_("error opening sync socket: %s"), safe_strerror (errno));
 153       return -1;
 154     }
 155
 156   addr.sun_family = AF_UNIX;
 157
 158   res = xsnprintf (addr.sun_path, UNIX_PATH_MAX, "%s", path);
 159   if (res >= UNIX_PATH_MAX)
 160     {
 161       warning (_("string overflow allocating socket name"));
 162       close (fd);
 163       return -1;
 164     }
 165
 166   res = connect (fd, (struct sockaddr *) &addr, sizeof (addr));
 167   if (res == -1)
 168     {
 169       warning (_("error connecting sync socket (%s): %s. "
 170                  "Make sure the directory exists and that it is writable."),
 171                  path, safe_strerror (errno));
 172       close (fd);
 173       return -1;
 174     }
 175
 176   return fd;
 177 #else
 178   return -1;
 179 #endif
 180 }
 181
 182 /* Execute an agent command in the inferior.  PID is the value of pid of the
 183    inferior.  CMD is the buffer for command.  GDB or GDBserver will store the
 184    command into it and fetch the return result from CMD.  The interaction
 185    between GDB/GDBserver and the agent is synchronized by a synchronization
 186    socket.  Return zero if success, otherwise return non-zero.  */
 187
 188 int
 189 agent_run_command (int pid, const char *cmd, int len)
 190 {
 191   int fd;
 192   int tid = agent_get_helper_thread_id ();
 193   ptid_t ptid = ptid_t (pid, tid, 0);
 194
 195   int ret = target_write_memory (ipa_sym_addrs.addr_cmd_buf,
 196                                  (gdb_byte *) cmd, len);
 197
 198   if (ret != 0)
 199     {
 200       warning (_("unable to write"));
 201       return -1;
 202     }
 203
 204   DEBUG_AGENT ("agent: resumed helper thread\n");
 205
 206   /* Resume helper thread.  */
 207   target_continue_no_signal (ptid);
 208
 209   fd = gdb_connect_sync_socket (pid);
 210   if (fd >= 0)
 211     {
 212       char buf[1] = "";
 213
 214       DEBUG_AGENT ("agent: signalling helper thread\n");
 215
 216       do
 217         {
 218           ret = write (fd, buf, 1);
 219         } while (ret == -1 && errno == EINTR);
 220
 221         DEBUG_AGENT ("agent: waiting for helper thread's response\n");
 222
 223       do
 224         {
 225           ret = read (fd, buf, 1);
 226         } while (ret == -1 && errno == EINTR);
 227
 228       close (fd);
 229
 230       DEBUG_AGENT ("agent: helper thread's response received\n");
 231     }
 232   else
 233     return -1;
 234
 235   /* Need to read response with the inferior stopped.  */
 236   if (ptid != null_ptid)
 237     {
 238       /* Stop thread PTID.  */
 239       DEBUG_AGENT ("agent: stop helper thread\n");
 240       target_stop_and_wait (ptid);
 241     }
 242
 243   if (fd >= 0)
 244     {
 245       if (target_read_memory (ipa_sym_addrs.addr_cmd_buf, (gdb_byte *) cmd,
 246                               IPA_CMD_BUF_SIZE))
 247         {
 248           warning (_("Error reading command response"));
 249           return -1;
 250         }
 251     }
 252
 253   return 0;
 254 }
 255
 256 /* Each bit of it stands for a capability of agent.  */
 257 static uint32_t agent_capability = 0;
 258
 259 /* Return true if agent has capability AGENT_CAP, otherwise return false.  */
 260
 261 bool
 262 agent_capability_check (enum agent_capa agent_capa)
 263 {
 264   if (agent_capability == 0)
 265     {
 266       if (target_read_uint32 (ipa_sym_addrs.addr_capability,
 267                               &agent_capability))
 268         warning (_("Error reading capability of agent"));
 269     }
 270   return (agent_capability & agent_capa) != 0;
 271 }
 272
 273 /* Invalidate the cache of agent capability, so we'll read it from inferior
 274    again.  Call it when launches a new program or reconnect to remote stub.  */
 275
 276 void
 277 agent_capability_invalidate (void)
 278 {
 279   agent_capability = 0;
 280 }