gdbsupport/agent.cc

   1 /* Shared utility routines for GDB to interact with agent.
   2
   3    Copyright (C) 2009-2023 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
 183    of the inferior.  CMD is the buffer for command.  It is assumed to
 184    be at least IPA_CMD_BUF_SIZE bytes long.  GDB or GDBserver will
 185    store the command into it and fetch the return result from CMD.
 186    The interaction between GDB/GDBserver and the agent is synchronized
 187    by a synchronization socket.  Return zero if success, otherwise
 188    return non-zero.  */
 189
 190 int
 191 agent_run_command (int pid, char *cmd, int len)
 192 {
 193   int fd;
 194   int tid = agent_get_helper_thread_id ();
 195   ptid_t ptid = ptid_t (pid, tid);
 196
 197   int ret = target_write_memory (ipa_sym_addrs.addr_cmd_buf,
 198                                  (gdb_byte *) cmd, len);
 199
 200   if (ret != 0)
 201     {
 202       warning (_("unable to write"));
 203       return -1;
 204     }
 205
 206   DEBUG_AGENT ("agent: resumed helper thread\n");
 207
 208   /* Resume helper thread.  */
 209   target_continue_no_signal (ptid);
 210
 211   fd = gdb_connect_sync_socket (pid);
 212   if (fd >= 0)
 213     {
 214       char buf[1] = "";
 215
 216       DEBUG_AGENT ("agent: signalling helper thread\n");
 217
 218       do
 219         {
 220           ret = write (fd, buf, 1);
 221         } while (ret == -1 && errno == EINTR);
 222
 223         DEBUG_AGENT ("agent: waiting for helper thread's response\n");
 224
 225       do
 226         {
 227           ret = read (fd, buf, 1);
 228         } while (ret == -1 && errno == EINTR);
 229
 230       close (fd);
 231
 232       DEBUG_AGENT ("agent: helper thread's response received\n");
 233     }
 234   else
 235     return -1;
 236
 237   /* Need to read response with the inferior stopped.  */
 238   if (ptid != null_ptid)
 239     {
 240       /* Stop thread PTID.  */
 241       DEBUG_AGENT ("agent: stop helper thread\n");
 242       target_stop_and_wait (ptid);
 243     }
 244
 245   if (fd >= 0)
 246     {
 247       if (target_read_memory (ipa_sym_addrs.addr_cmd_buf, (gdb_byte *) cmd,
 248                               IPA_CMD_BUF_SIZE))
 249         {
 250           warning (_("Error reading command response"));
 251           return -1;
 252         }
 253     }
 254
 255   return 0;
 256 }
 257
 258 /* Each bit of it stands for a capability of agent.  */
 259 static uint32_t agent_capability = 0;
 260
 261 /* Return true if agent has capability AGENT_CAP, otherwise return false.  */
 262
 263 bool
 264 agent_capability_check (enum agent_capa agent_capa)
 265 {
 266   if (agent_capability == 0)
 267     {
 268       if (target_read_uint32 (ipa_sym_addrs.addr_capability,
 269                               &agent_capability))
 270         warning (_("Error reading capability of agent"));
 271     }
 272   return (agent_capability & agent_capa) != 0;
 273 }
 274
 275 /* Invalidate the cache of agent capability, so we'll read it from inferior
 276    again.  Call it when launches a new program or reconnect to remote stub.  */
 277
 278 void
 279 agent_capability_invalidate (void)
 280 {
 281   agent_capability = 0;
 282 }