11 #include "snapshot-interface.h"
14 #include "threads-model.h"
16 #include "traceanalysis.h"
17 #include "execution.h"
19 #include "bugmessage.h"
22 ModelChecker *model = NULL;
24 /** Wrapper to run the user's main function, with appropriate arguments */
25 void user_main_wrapper(void *)
27 user_main(model->params.argc, model->params.argv);
30 /** @brief Constructor */
31 ModelChecker::ModelChecker() :
32 /* Initialize default scheduler */
35 scheduler(new Scheduler()),
36 execution(new ModelExecution(this, scheduler)),
37 history(new ModelHistory()),
42 memset(&stats,0,sizeof(struct execution_stats));
43 init_thread = new Thread(execution->get_next_id(), (thrd_t *) model_malloc(sizeof(thrd_t)), &user_main_wrapper, NULL, NULL); // L: user_main_wrapper passes the user program
44 execution->add_thread(init_thread);
45 scheduler->set_current_thread(init_thread);
46 execution->setParams(¶ms);
47 param_defaults(¶ms);
51 /** @brief Destructor */
52 ModelChecker::~ModelChecker()
57 /** Method to set parameters */
58 model_params * ModelChecker::getParams() {
63 * Restores user program to initial state and resets all model-checker data
66 void ModelChecker::reset_to_initial_state()
70 * FIXME: if we utilize partial rollback, we will need to free only
71 * those pending actions which were NOT pending before the rollback
74 for (unsigned int i = 0;i < get_num_threads();i++)
75 delete get_thread(int_to_id(i))->get_pending();
77 snapshot_backtrack_before(0);
80 /** @return the number of user threads created during this execution */
81 unsigned int ModelChecker::get_num_threads() const
83 return execution->get_num_threads();
87 * Must be called from user-thread context (e.g., through the global
88 * thread_current() interface)
90 * @return The currently executing Thread.
92 Thread * ModelChecker::get_current_thread() const
94 return scheduler->get_current_thread();
98 * @brief Choose the next thread to execute.
100 * This function chooses the next thread that should execute. It can enforce
101 * execution replay/backtracking or, if the model-checker has no preference
102 * regarding the next thread (i.e., when exploring a new execution ordering),
103 * we defer to the scheduler.
105 * @return The next chosen thread to run, if any exist. Or else if the current
106 * execution should terminate, return NULL.
108 Thread * ModelChecker::get_next_thread()
112 * Have we completed exploring the preselected path? Then let the
115 return scheduler->select_next_thread();
119 * @brief Assert a bug in the executing program.
121 * Use this function to assert any sort of bug in the user program. If the
122 * current trace is feasible (actually, a prefix of some feasible execution),
123 * then this execution will be aborted, printing the appropriate message. If
124 * the current trace is not yet feasible, the error message will be stashed and
125 * printed if the execution ever becomes feasible.
127 * @param msg Descriptive message for the bug (do not include newline char)
128 * @return True if bug is immediately-feasible
130 bool ModelChecker::assert_bug(const char *msg, ...)
136 vsnprintf(str, sizeof(str), msg, ap);
139 return execution->assert_bug(str);
143 * @brief Assert a bug in the executing program, asserted by a user thread
144 * @see ModelChecker::assert_bug
145 * @param msg Descriptive message for the bug (do not include newline char)
147 void ModelChecker::assert_user_bug(const char *msg)
149 /* If feasible bug, bail out now */
151 switch_to_master(NULL);
154 /** @brief Print bug report listing for this execution (if any bugs exist) */
155 void ModelChecker::print_bugs() const
157 SnapVector<bug_message *> *bugs = execution->get_bugs();
159 model_print("Bug report: %zu bug%s detected\n",
161 bugs->size() > 1 ? "s" : "");
162 for (unsigned int i = 0;i < bugs->size();i++)
163 (*bugs)[i] -> print();
167 * @brief Record end-of-execution stats
169 * Must be run when exiting an execution. Records various stats.
170 * @see struct execution_stats
172 void ModelChecker::record_stats()
175 if (!execution->isfeasibleprefix())
176 stats.num_infeasible ++;
177 else if (execution->have_bug_reports())
178 stats.num_buggy_executions ++;
179 else if (execution->is_complete_execution())
180 stats.num_complete ++;
182 stats.num_redundant ++;
185 * @todo We can violate this ASSERT() when fairness/sleep sets
186 * conflict to cause an execution to terminate, e.g. with:
187 * Scheduler: [0: disabled][1: disabled][2: sleep][3: current, enabled]
189 //ASSERT(scheduler->all_threads_sleeping());
193 /** @brief Print execution stats */
194 void ModelChecker::print_stats() const
196 model_print("Number of complete, bug-free executions: %d\n", stats.num_complete);
197 model_print("Number of redundant executions: %d\n", stats.num_redundant);
198 model_print("Number of buggy executions: %d\n", stats.num_buggy_executions);
199 model_print("Number of infeasible executions: %d\n", stats.num_infeasible);
200 model_print("Total executions: %d\n", stats.num_total);
204 * @brief End-of-exeuction print
205 * @param printbugs Should any existing bugs be printed?
207 void ModelChecker::print_execution(bool printbugs) const
209 model_print("Program output from execution %d:\n",
210 get_execution_number());
211 print_program_output();
213 if (params.verbose >= 3) {
217 /* Don't print invalid bugs */
218 if (printbugs && execution->have_bug_reports()) {
224 execution->print_summary();
228 * Queries the model-checker for more executions to explore and, if one
229 * exists, resets the model-checker state to execute a new execution.
231 * @return If there are more executions to explore, return true. Otherwise,
234 bool ModelChecker::next_execution()
237 /* Is this execution a feasible execution that's worth bug-checking? */
238 bool complete = execution->isfeasibleprefix() &&
239 (execution->is_complete_execution() ||
240 execution->have_bug_reports());
242 /* End-of-execution bug checks */
244 if (execution->is_deadlocked())
245 assert_bug("Deadlock detected");
247 run_trace_analyses();
252 if ( (complete && params.verbose) || params.verbose>1 || (complete && execution->have_bug_reports()))
253 print_execution(complete);
255 clear_program_output();
263 reset_to_initial_state();
267 /** @brief Run trace analyses on complete trace */
268 void ModelChecker::run_trace_analyses() {
269 for (unsigned int i = 0;i < trace_analyses.size();i ++)
270 trace_analyses[i] -> analyze(execution->get_action_trace());
274 * @brief Get a Thread reference by its ID
275 * @param tid The Thread's ID
276 * @return A Thread reference
278 Thread * ModelChecker::get_thread(thread_id_t tid) const
280 return execution->get_thread(tid);
284 * @brief Get a reference to the Thread in which a ModelAction was executed
285 * @param act The ModelAction
286 * @return A Thread reference
288 Thread * ModelChecker::get_thread(const ModelAction *act) const
290 return execution->get_thread(act);
294 * Switch from a model-checker context to a user-thread context. This is the
295 * complement of ModelChecker::switch_to_master and must be called from the
296 * model-checker context
298 * @param thread The user-thread to switch to
300 void ModelChecker::switch_from_master(Thread *thread)
302 scheduler->set_current_thread(thread);
303 Thread::swap(&system_context, thread);
307 * Switch from a user-context to the "master thread" context (a.k.a. system
308 * context). This switch is made with the intention of exploring a particular
309 * model-checking action (described by a ModelAction object). Must be called
310 * from a user-thread context.
312 * @param act The current action that will be explored. May be NULL only if
313 * trace is exiting via an assertion (see ModelExecution::set_assert and
314 * ModelExecution::has_asserted).
315 * @return Return the value returned by the current action
317 uint64_t ModelChecker::switch_to_master(ModelAction *act)
320 static bool fork_message_printed = false;
322 if (!fork_message_printed) {
323 model_print("Fork handler trying to call into model checker...\n");
324 fork_message_printed = true;
330 Thread *old = thread_current();
331 scheduler->set_current_thread(NULL);
332 ASSERT(!old->get_pending());
334 if (inspect_plugin != NULL) {
335 inspect_plugin->inspectModelAction(act);
338 old->set_pending(act);
339 if (Thread::swap(old, &system_context) < 0) {
340 perror("swap threads");
343 return old->get_return_value();
346 static void runChecker() {
351 void ModelChecker::startChecker() {
352 startExecution(get_system_context(), runChecker);
355 bool ModelChecker::should_terminate_execution()
357 /* Infeasible -> don't take any more steps */
358 if (execution->is_infeasible())
360 else if (execution->isfeasibleprefix() && execution->have_fatal_bug_reports()) {
361 execution->set_assert();
367 /** @brief Restart ModelChecker upon returning to the run loop of the
369 void ModelChecker::restart()
374 void ModelChecker::do_restart()
376 restart_flag = false;
377 reset_to_initial_state();
378 memset(&stats,0,sizeof(struct execution_stats));
379 execution_number = 1;
382 void ModelChecker::startMainThread() {
383 init_thread->set_state(THREAD_RUNNING);
384 scheduler->set_current_thread(init_thread);
388 static bool is_nonsc_write(const ModelAction *act) {
389 if (act->get_type() == ATOMIC_WRITE) {
390 std::memory_order order = act->get_mo();
392 case std::memory_order_relaxed:
393 case std::memory_order_release:
402 /** @brief Run ModelChecker for the user program */
403 void ModelChecker::run()
405 //Need to initial random number generator state to avoid resets on rollback
406 char random_state[256];
407 initstate(423121, random_state, sizeof(random_state));
409 for(int exec = 0;exec < params.maxexecutions;exec++) {
410 Thread * t = init_thread;
414 * Stash next pending action(s) for thread(s). There
415 * should only need to stash one thread's action--the
416 * thread which just took a step--plus the first step
417 * for any newly-created thread
419 ModelAction * pending;
420 for (unsigned int i = 0;i < get_num_threads();i++) {
421 thread_id_t tid = int_to_id(i);
422 Thread *thr = get_thread(tid);
423 if (!thr->is_model_thread() && !thr->is_complete() && ((!(pending=thr->get_pending())) || is_nonsc_write(pending)) ) {
424 switch_from_master(thr); // L: context swapped, and action type of thr changed.
425 if (thr->is_waiting_on(thr))
426 assert_bug("Deadlock detected (thread %u)", i);
430 /* Don't schedule threads which should be disabled */
431 for (unsigned int i = 0;i < get_num_threads();i++) {
432 Thread *th = get_thread(int_to_id(i));
433 ModelAction *act = th->get_pending();
434 if (act && execution->is_enabled(th) && !execution->check_action_enabled(act)) {
435 scheduler->sleep(th);
439 for (unsigned int i = 1;i < get_num_threads();i++) {
440 Thread *th = get_thread(int_to_id(i));
441 ModelAction *act = th->get_pending();
442 if (act && execution->is_enabled(th) && (th->get_state() != THREAD_BLOCKED) ) {
443 if (act->is_write()) {
444 std::memory_order order = act->get_mo();
445 if (order == std::memory_order_relaxed || \
446 order == std::memory_order_release) {
450 } else if (act->get_type() == THREAD_CREATE || \
451 act->get_type() == PTHREAD_CREATE || \
452 act->get_type() == THREAD_START || \
453 act->get_type() == THREAD_FINISH) {
460 /* Catch assertions from prior take_step or from
461 * between-ModelAction bugs (e.g., data races) */
463 if (execution->has_asserted())
466 t = get_next_thread();
467 if (!t || t->is_model_thread())
470 /* Consume the next action for a Thread */
471 ModelAction *curr = t->get_pending();
472 t->set_pending(NULL);
473 t = execution->take_step(curr);
474 } while (!should_terminate_execution());
476 //restore random number generator state after rollback
477 setstate(random_state);
480 model_print("******* Model-checking complete: *******\n");
483 /* Have the trace analyses dump their output. */
484 for (unsigned int i = 0;i < trace_analyses.size();i++)
485 trace_analyses[i]->finish();