1 /* Copyright (c) 2015-2023. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "src/mc/api/RemoteApp.hpp"
7 #include "src/mc/explo/Exploration.hpp"
8 #include "src/mc/mc_config.hpp"
9 #include "xbt/asserts.h"
10 #include "src/mc/api/State.hpp"
11 #include "src/mc/mc_config.hpp"
12 #include "src/mc/mc_exit.hpp"
13 #include "src/mc/mc_private.hpp"
15 #include "xbt/system_error.hpp"
20 #include <boost/tokenizer.hpp>
27 #include <sys/personality.h>
28 #include <sys/prctl.h>
30 #include <sys/ptrace.h>
34 #define WAITPID_CHECKED_FLAGS __WALL
36 #define WAITPID_CHECKED_FLAGS 0
39 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_Session, mc, "Model-checker session");
40 XBT_LOG_EXTERNAL_CATEGORY(mc_global);
42 static simgrid::config::Flag<std::string> _sg_mc_setenv{
43 "model-check/setenv", "Extra environment variables to pass to the child process (ex: 'AZE=aze;QWE=qwe').", "",
44 [](std::string_view value) {
45 xbt_assert(value.empty() || value.find('=', 0) != std::string_view::npos,
46 "The 'model-check/setenv' parameter must be like 'AZE=aze', but it does not contain an equal sign.");
49 namespace simgrid::mc {
51 XBT_ATTRIB_NORETURN static void run_child_process(int socket, const std::vector<char*>& args)
53 /* On startup, simix_global_init() calls simgrid::mc::Client::initialize(), which checks whether the MC_ENV_SOCKET_FD
54 * env variable is set. If so, MC mode is assumed, and the client is setup from its side
58 // Make sure we do not outlive our parent
61 xbt_assert(sigprocmask(SIG_SETMASK, &mask, nullptr) >= 0, "Could not unblock signals");
62 xbt_assert(prctl(PR_SET_PDEATHSIG, SIGHUP) == 0, "Could not PR_SET_PDEATHSIG");
64 // Make sure that the application process layout is not randomized, so that the info we gather is stable over re-execs
65 if (personality(ADDR_NO_RANDOMIZE) == -1) {
66 XBT_ERROR("Could not set the NO_RANDOMIZE personality");
67 throw xbt::errno_error();
71 // Remove CLOEXEC to pass the socket to the application
72 int fdflags = fcntl(socket, F_GETFD, 0);
73 xbt_assert(fdflags != -1 && fcntl(socket, F_SETFD, fdflags & ~FD_CLOEXEC) != -1,
74 "Could not remove CLOEXEC for socket");
76 setenv(MC_ENV_SOCKET_FD, std::to_string(socket).c_str(), 1);
78 /* Setup the tokenizer that parses the cfg:model-check/setenv parameter */
79 using Tokenizer = boost::tokenizer<boost::char_separator<char>>;
80 boost::char_separator<char> semicol_sep(";");
81 boost::char_separator<char> equal_sep("=");
82 Tokenizer token_vars(_sg_mc_setenv.get(), semicol_sep); /* Iterate over all FOO=foo parts */
83 for (const auto& token : token_vars) {
84 std::vector<std::string> kv;
85 Tokenizer token_kv(token, equal_sep);
86 for (const auto& t : token_kv) /* Iterate over 'FOO' and then 'foo' in that 'FOO=foo' */
88 xbt_assert(kv.size() == 2, "Parse error on 'model-check/setenv' value %s. Does it contain an equal sign?",
90 XBT_INFO("setenv '%s'='%s'", kv[0].c_str(), kv[1].c_str());
91 setenv(kv[0].c_str(), kv[1].c_str(), 1);
94 /* And now, exec the child process */
96 while (args[i] != nullptr && args[i][0] == '-')
99 xbt_assert(args[i] != nullptr,
100 "Unable to find a binary to exec on the command line. Did you only pass config flags?");
102 execvp(args[i], args.data() + i);
103 XBT_CRITICAL("The model-checked process failed to exec(%s): %s.\n"
104 " Make sure that your binary exists on disk and is executable.",
105 args[i], strerror(errno));
106 if (strchr(args[i], '=') != nullptr)
107 XBT_CRITICAL("If you want to pass environment variables to the application, please use --cfg=model-check/setenv:%s",
110 xbt_die("Aborting now.");
113 RemoteApp::RemoteApp(const std::vector<char*>& args)
115 // Create an AF_LOCAL socketpair used for exchanging messages
116 // between the model-checker process (ourselves) and the model-checked
119 xbt_assert(socketpair(AF_LOCAL, SOCK_SEQPACKET | SOCK_CLOEXEC, 0, sockets) != -1, "Could not create socketpair");
122 xbt_assert(pid >= 0, "Could not fork model-checked process");
124 if (pid == 0) { // Child
126 run_child_process(sockets[0], args);
130 // Parent (model-checker):
133 checker_side_ = std::make_unique<simgrid::mc::CheckerSide>(sockets[1], pid);
137 /* Take the initial snapshot */
139 initial_snapshot_ = std::make_shared<simgrid::mc::Snapshot>(0, page_store_, checker_side_->get_remote_memory());
142 RemoteApp::~RemoteApp()
144 initial_snapshot_ = nullptr;
147 void RemoteApp::start()
149 XBT_DEBUG("Waiting for the model-checked process");
152 // The model-checked process SIGSTOP itself to signal it's ready:
153 const pid_t pid = checker_side_->get_pid();
155 xbt_assert(waitpid(pid, &status, WAITPID_CHECKED_FLAGS) == pid && WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP,
156 "Could not wait model-checked process");
160 ptrace(PTRACE_SETOPTIONS, pid, nullptr, PTRACE_O_TRACEEXIT);
161 ptrace(PTRACE_CONT, pid, 0, 0);
163 ptrace(PT_CONTINUE, pid, (caddr_t)1, 0);
165 #error "no ptrace equivalent coded for this platform"
167 xbt_assert(errno == 0,
168 "Ptrace does not seem to be usable in your setup (errno: %d). "
169 "If you run from within a docker, adding `--cap-add SYS_PTRACE` to the docker line may help. "
170 "If it does not help, please report this bug.",
173 void RemoteApp::restore_initial_state() const
175 this->initial_snapshot_->restore(checker_side_->get_remote_memory());
178 unsigned long RemoteApp::get_maxpid() const
180 // note: we could maybe cache it and count the actor creation on checker side too.
181 // But counting correctly accross state checkpoint/restore would be annoying.
183 checker_side_->get_channel().send(MessageType::ACTORS_MAXPID);
184 s_mc_message_int_t answer;
185 ssize_t answer_size = checker_side_->get_channel().receive(answer);
186 xbt_assert(answer_size != -1, "Could not receive message");
187 xbt_assert(answer_size == sizeof answer, "Broken message (size=%zd; expected %zu)", answer_size, sizeof answer);
188 xbt_assert(answer.type == MessageType::ACTORS_MAXPID_REPLY,
189 "Received unexpected message %s (%i); expected MessageType::ACTORS_MAXPID_REPLY (%i)",
190 to_c_str(answer.type), (int)answer.type, (int)MessageType::ACTORS_MAXPID_REPLY);
195 void RemoteApp::get_actors_status(std::map<aid_t, ActorState>& whereto) const
197 // The messaging happens as follows:
199 // CheckerSide AppSide
200 // send ACTORS_STATUS ---->
201 // <----- send ACTORS_STATUS_REPLY
202 // <----- send `N` `s_mc_message_actors_status_one_t` structs
203 // <----- send `M` `s_mc_message_simcall_probe_one_t` structs
204 checker_side_->get_channel().send(MessageType::ACTORS_STATUS);
206 s_mc_message_actors_status_answer_t answer;
207 ssize_t answer_size = checker_side_->get_channel().receive(answer);
208 xbt_assert(answer_size != -1, "Could not receive message");
209 xbt_assert(answer_size == sizeof answer, "Broken message (size=%zd; expected %zu)", answer_size, sizeof answer);
210 xbt_assert(answer.type == MessageType::ACTORS_STATUS_REPLY,
211 "Received unexpected message %s (%i); expected MessageType::ACTORS_STATUS_REPLY (%i)",
212 to_c_str(answer.type), (int)answer.type, (int)MessageType::ACTORS_STATUS_REPLY);
214 // Message sanity checks
215 xbt_assert(answer.count >= 0, "Received an ACTOR_STATUS_REPLY message with an actor count of '%d' < 0", answer.count);
216 xbt_assert(answer.transition_count >= 0, "Received an ACTOR_STATUS_REPLY message with transition_count '%d' < 0",
217 answer.transition_count);
218 xbt_assert(answer.transition_count == 0 || answer.count >= 0,
219 "Received an ACTOR_STATUS_REPLY message with no actor data "
220 "but with transition data nonetheless");
222 std::vector<s_mc_message_actors_status_one_t> status(answer.count);
223 if (answer.count > 0) {
224 size_t size = status.size() * sizeof(s_mc_message_actors_status_one_t);
225 ssize_t received = checker_side_->get_channel().receive(status.data(), size);
226 xbt_assert(static_cast<size_t>(received) == size);
229 // Ensures that each actor sends precisely `answer.transition_count` transitions. While technically
230 // this doesn't catch the edge case where actor A sends 3 instead of 2 and actor B sends 2 instead
231 // of 3 transitions, that is ignored here since that invariant needs to be enforced on the AppSide
232 const auto expected_transitions = std::accumulate(
233 status.begin(), status.end(), 0, [](int total, const auto& actor) { return total + actor.n_transitions; });
234 xbt_assert(expected_transitions == answer.transition_count,
235 "Expected to receive %d transition(s) but was only notified of %d by the app side", expected_transitions,
236 answer.transition_count);
238 std::vector<s_mc_message_simcall_probe_one_t> probes(answer.transition_count);
239 if (answer.transition_count > 0) {
240 for (auto& probe : probes) {
241 ssize_t received = checker_side_->get_channel().receive(probe);
242 xbt_assert(received >= 0, "Could not receive response to ACTORS_PROBE message (%s)", strerror(errno));
243 xbt_assert(static_cast<size_t>(received) == sizeof probe,
244 "Could not receive response to ACTORS_PROBE message (%zd bytes received != %zu bytes expected",
245 received, sizeof probe);
250 std::move_iterator probes_iter(probes.begin());
252 for (const auto& actor : status) {
253 xbt_assert(actor.n_transitions == 0 || actor.n_transitions == actor.max_considered,
254 "If any transitions are serialized for an actor, it must match the "
255 "total number of transitions that can be considered for the actor "
256 "(currently %d), but only %d transition(s) was/were said to be encoded",
257 actor.max_considered, actor.n_transitions);
259 std::vector<std::shared_ptr<Transition>> actor_transitions;
260 for (int times_considered = 0; times_considered < actor.n_transitions; times_considered++, probes_iter++) {
261 std::stringstream stream((*probes_iter).buffer.data());
262 actor_transitions.emplace_back(deserialize_transition(actor.aid, times_considered, stream));
265 XBT_DEBUG("Received %zu transitions for actor %ld", actor_transitions.size(), actor.aid);
266 whereto.try_emplace(actor.aid, actor.aid, actor.enabled, actor.max_considered, std::move(actor_transitions));
270 void RemoteApp::check_deadlock() const
272 xbt_assert(checker_side_->get_channel().send(MessageType::DEADLOCK_CHECK) == 0, "Could not check deadlock state");
273 s_mc_message_int_t message;
274 ssize_t received = checker_side_->get_channel().receive(message);
275 xbt_assert(received != -1, "Could not receive message");
276 xbt_assert(received == sizeof message, "Broken message (size=%zd; expected %zu)", received, sizeof message);
277 xbt_assert(message.type == MessageType::DEADLOCK_CHECK_REPLY,
278 "Received unexpected message %s (%i); expected MessageType::DEADLOCK_CHECK_REPLY (%i)",
279 to_c_str(message.type), (int)message.type, (int)MessageType::DEADLOCK_CHECK_REPLY);
281 if (message.value != 0) {
282 auto* explo = Exploration::get_instance();
283 XBT_CINFO(mc_global, "Counter-example execution trace:");
284 for (auto const& frame : explo->get_textual_trace())
285 XBT_CINFO(mc_global, " %s", frame.c_str());
286 XBT_INFO("You can debug the problem (and see the whole details) by rerunning out of simgrid-mc with "
287 "--cfg=model-check/replay:'%s'",
288 explo->get_record_trace().to_string().c_str());
290 throw DeadlockError();
294 void RemoteApp::wait_for_requests()
296 /* Resume the application */
297 if (checker_side_->get_channel().send(MessageType::CONTINUE) != 0)
298 throw xbt::errno_error();
299 checker_side_->clear_memory_cache();
301 if (checker_side_->running())
302 checker_side_->dispatch_events();
305 void RemoteApp::shutdown()
307 XBT_DEBUG("Shutting down model-checker");
309 if (checker_side_->running()) {
310 XBT_DEBUG("Killing process");
312 kill(checker_side_->get_pid(), SIGKILL);
313 checker_side_->terminate();
317 Transition* RemoteApp::handle_simcall(aid_t aid, int times_considered, bool new_transition)
319 s_mc_message_simcall_execute_t m = {};
320 m.type = MessageType::SIMCALL_EXECUTE;
322 m.times_considered_ = times_considered;
323 checker_side_->get_channel().send(m);
325 get_remote_process_memory().clear_cache();
326 if (checker_side_->running())
327 checker_side_->dispatch_events(); // The app may send messages while processing the transition
329 s_mc_message_simcall_execute_answer_t answer;
330 ssize_t s = checker_side_->get_channel().receive(answer);
331 xbt_assert(s != -1, "Could not receive message");
332 xbt_assert(s == sizeof answer, "Broken message (size=%zd; expected %zu)", s, sizeof answer);
333 xbt_assert(answer.type == MessageType::SIMCALL_EXECUTE_ANSWER,
334 "Received unexpected message %s (%i); expected MessageType::SIMCALL_EXECUTE_ANSWER (%i)",
335 to_c_str(answer.type), (int)answer.type, (int)MessageType::SIMCALL_EXECUTE_ANSWER);
337 if (new_transition) {
338 std::stringstream stream(answer.buffer.data());
339 return deserialize_transition(aid, times_considered, stream);
344 void RemoteApp::finalize_app(bool terminate_asap)
346 s_mc_message_int_t m = {};
347 m.type = MessageType::FINALIZE;
348 m.value = terminate_asap;
349 xbt_assert(checker_side_->get_channel().send(m) == 0, "Could not ask the app to finalize on need");
351 s_mc_message_t answer;
352 ssize_t s = checker_side_->get_channel().receive(answer);
353 xbt_assert(s != -1, "Could not receive answer to FINALIZE");
354 xbt_assert(s == sizeof answer, "Broken message (size=%zd; expected %zu)", s, sizeof answer);
355 xbt_assert(answer.type == MessageType::FINALIZE_REPLY,
356 "Received unexpected message %s (%i); expected MessageType::FINALIZE_REPLY (%i)", to_c_str(answer.type),
357 (int)answer.type, (int)MessageType::FINALIZE_REPLY);
360 } // namespace simgrid::mc