gdbsupport/agent.cc

   1 /* Shared utility routines for GDB to interact with agent.
   2
   3    Copyright (C) 2009-2024 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 "target/target.h"
  21 #include "gdbsupport/symbol.h"
  22 #include <unistd.h>
  23 #include "filestuff.h"
  24
  25 #define IPA_SYM_STRUCT_NAME ipa_sym_addresses_common
  26 #include "agent.h"
  27
  28 bool debug_agent = false;
  29
  30 /* A stdarg wrapper for debug_vprintf.  */
  31
  32 static void ATTRIBUTE_PRINTF (1, 2)
  33 debug_agent_printf (const char *fmt, ...)
  34 {
  35   va_list ap;
  36
  37   if (!debug_agent)
  38     return;
  39   va_start (ap, fmt);
  40   debug_vprintf (fmt, ap);
  41   va_end (ap);
  42 }
  43
  44 #define DEBUG_AGENT debug_agent_printf
  45
  46 /* Global flag to determine using agent or not.  */
  47 bool use_agent = false;
  48
  49 /* Addresses of in-process agent's symbols both GDB and GDBserver cares
  50    about.  */
  51
  52 struct ipa_sym_addresses_common
  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 uint32_t helper_thread_id = 0;
  62
  63 static struct
  64 {
  65   const char *name;
  66   int offset;
  67 } symbol_list[] = {
  68   IPA_SYM(helper_thread_id),
  69   IPA_SYM(cmd_buf),
  70   IPA_SYM(capability),
  71 };
  72
  73 static struct ipa_sym_addresses_common ipa_sym_addrs;
  74
  75 static bool all_agent_symbols_looked_up = false;
  76
  77 bool
  78 agent_loaded_p (void)
  79 {
  80   return all_agent_symbols_looked_up;
  81 }
  82
  83 /* Look up all symbols needed by agent.  Return 0 if all the symbols are
  84    found, return non-zero otherwise.  */
  85
  86 int
  87 agent_look_up_symbols (void *arg)
  88 {
  89   all_agent_symbols_looked_up = false;
  90
  91   for (int i = 0; i < sizeof (symbol_list) / sizeof (symbol_list[0]); i++)
  92     {
  93       CORE_ADDR *addrp =
  94         (CORE_ADDR *) ((char *) &ipa_sym_addrs + symbol_list[i].offset);
  95       struct objfile *objfile = (struct objfile *) arg;
  96
  97       if (find_minimal_symbol_address (symbol_list[i].name, addrp,
  98                                        objfile) != 0)
  99         {
 100           DEBUG_AGENT ("symbol `%s' not found\n", symbol_list[i].name);
 101           return -1;
 102         }
 103     }
 104
 105   all_agent_symbols_looked_up = true;
 106   return 0;
 107 }
 108
 109 static unsigned int
 110 agent_get_helper_thread_id (void)
 111 {
 112   if  (helper_thread_id == 0)
 113     {
 114       if (target_read_uint32 (ipa_sym_addrs.addr_helper_thread_id,
 115                               &helper_thread_id))
 116         warning (_("Error reading helper thread's id in lib"));
 117     }
 118
 119   return helper_thread_id;
 120 }
 121
 122 #ifdef HAVE_SYS_UN_H
 123 #include <sys/socket.h>
 124 #include <sys/un.h>
 125 #define SOCK_DIR P_tmpdir
 126
 127 #ifndef UNIX_PATH_MAX
 128 #define UNIX_PATH_MAX sizeof(((struct sockaddr_un *) NULL)->sun_path)
 129 #endif
 130
 131 #endif
 132
 133 /* Connects to synchronization socket.  PID is the pid of inferior, which is
 134    used to set up the connection socket.  */
 135
 136 static int
 137 gdb_connect_sync_socket (int pid)
 138 {
 139 #ifdef HAVE_SYS_UN_H
 140   struct sockaddr_un addr = {};
 141   int res, fd;
 142   char path[UNIX_PATH_MAX];
 143
 144   res = xsnprintf (path, UNIX_PATH_MAX, "%s/gdb_ust%d", P_tmpdir, pid);
 145   if (res >= UNIX_PATH_MAX)
 146     return -1;
 147
 148   res = fd = gdb_socket_cloexec (PF_UNIX, SOCK_STREAM, 0);
 149   if (res == -1)
 150     {
 151       warning (_("error opening sync socket: %s"), safe_strerror (errno));
 152       return -1;
 153     }
 154
 155   addr.sun_family = AF_UNIX;
 156
 157   res = xsnprintf (addr.sun_path, UNIX_PATH_MAX, "%s", path);
 158   if (res >= UNIX_PATH_MAX)
 159     {
 160       warning (_("string overflow allocating socket name"));
 161       close (fd);
 162       return -1;
 163     }
 164
 165   res = connect (fd, (struct sockaddr *) &addr, sizeof (addr));
 166   if (res == -1)
 167     {
 168       warning (_("error connecting sync socket (%s): %s. "
 169                  "Make sure the directory exists and that it is writable."),
 170                  path, safe_strerror (errno));
 171       close (fd);
 172       return -1;
 173     }
 174
 175   return fd;
 176 #else
 177   return -1;
 178 #endif
 179 }
 180
 181 /* Execute an agent command in the inferior.  PID is the value of pid
 182    of the inferior.  CMD is the buffer for command.  It is assumed to
 183    be at least IPA_CMD_BUF_SIZE bytes long.  GDB or GDBserver will
 184    store the command into it and fetch the return result from CMD.
 185    The interaction between GDB/GDBserver and the agent is synchronized
 186    by a synchronization socket.  Return zero if success, otherwise
 187    return non-zero.  */
 188
 189 int
 190 agent_run_command (int pid, char *cmd, int len)
 191 {
 192   int fd;
 193   int tid = agent_get_helper_thread_id ();
 194   ptid_t ptid = ptid_t (pid, tid);
 195
 196   int ret = target_write_memory (ipa_sym_addrs.addr_cmd_buf,
 197                                  (gdb_byte *) cmd, len);
 198
 199   if (ret != 0)
 200     {
 201       warning (_("unable to write"));
 202       return -1;
 203     }
 204
 205   DEBUG_AGENT ("agent: resumed helper thread\n");
 206
 207   /* Resume helper thread.  */
 208   target_continue_no_signal (ptid);
 209
 210   fd = gdb_connect_sync_socket (pid);
 211   if (fd >= 0)
 212     {
 213       char buf[1] = "";
 214
 215       DEBUG_AGENT ("agent: signalling helper thread\n");
 216
 217       do
 218         {
 219           ret = write (fd, buf, 1);
 220         } while (ret == -1 && errno == EINTR);
 221
 222         DEBUG_AGENT ("agent: waiting for helper thread's response\n");
 223
 224       do
 225         {
 226           ret = read (fd, buf, 1);
 227         } while (ret == -1 && errno == EINTR);
 228
 229       close (fd);
 230
 231       DEBUG_AGENT ("agent: helper thread's response received\n");
 232     }
 233   else
 234     return -1;
 235
 236   /* Need to read response with the inferior stopped.  */
 237   if (ptid != null_ptid)
 238     {
 239       /* Stop thread PTID.  */
 240       DEBUG_AGENT ("agent: stop helper thread\n");
 241       target_stop_and_wait (ptid);
 242     }
 243
 244   if (fd >= 0)
 245     {
 246       if (target_read_memory (ipa_sym_addrs.addr_cmd_buf, (gdb_byte *) cmd,
 247                               IPA_CMD_BUF_SIZE))
 248         {
 249           warning (_("Error reading command response"));
 250           return -1;
 251         }
 252     }
 253
 254   return 0;
 255 }
 256
 257 /* Each bit of it stands for a capability of agent.  */
 258 static uint32_t agent_capability = 0;
 259
 260 /* Return true if agent has capability AGENT_CAP, otherwise return false.  */
 261
 262 bool
 263 agent_capability_check (enum agent_capa agent_capa)
 264 {
 265   if (agent_capability == 0)
 266     {
 267       if (target_read_uint32 (ipa_sym_addrs.addr_capability,
 268                               &agent_capability))
 269         warning (_("Error reading capability of agent"));
 270     }
 271   return (agent_capability & agent_capa) != 0;
 272 }
 273
 274 /* Invalidate the cache of agent capability, so we'll read it from inferior
 275    again.  Call it when launches a new program or reconnect to remote stub.  */
 276
 277 void
 278 agent_capability_invalidate (void)
 279 {
 280   agent_capability = 0;
 281 }