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
29bool debug_agent = false;
30
31/* A stdarg wrapper for debug_vprintf.  */
32
33static void ATTRIBUTE_PRINTF (1, 2)
34debug_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.  */
48bool use_agent = false;
49
50/* Addresses of in-process agent's symbols both GDB and GDBserver cares
51   about.  */
52
53struct 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.  */
62static uint32_t helper_thread_id = 0;
63
64static 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
74static struct ipa_sym_addresses_common ipa_sym_addrs;
75
76static bool all_agent_symbols_looked_up = false;
77
78bool
79agent_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
87int
88agent_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
110static unsigned int
111agent_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
137static int
138gdb_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
188int
189agent_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.  */
257static uint32_t agent_capability = 0;
258
259/* Return true if agent has capability AGENT_CAP, otherwise return false.  */
260
261bool
262agent_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
276void
277agent_capability_invalidate (void)
278{
279  agent_capability = 0;
280}
281