X-Git-Url: http://plrg.eecs.uci.edu/git/?p=c11tester.git;a=blobdiff_plain;f=model.cc;h=c2de31304f577187d538075de45504a94f7019b9;hp=7ae63b69334c1a35faae4d94a4dde0fcf5be4c7b;hb=db17cfb8915ef5b6b2977360c05a92b1b7e01a3e;hpb=805cb1992146bc8f5d69e3e98a4b2f941a407001

diff --git a/model.cc b/model.cc
index 7ae63b69..c2de3130 100644
--- a/model.cc
+++ b/model.cc
@@ -26,11 +26,41 @@ void placeholder(void *) {
 	ASSERT(0);
 }
 
+#include <signal.h>
+
+#define SIGSTACKSIZE 65536
+static void mprot_handle_pf(int sig, siginfo_t *si, void *unused)
+{
+	model_print("Segmentation fault at %p\n", si->si_addr);
+	model_print("For debugging, place breakpoint at: %s:%d\n",
+							__FILE__, __LINE__);
+	print_trace();	// Trace printing may cause dynamic memory allocation
+	while(1)
+		;
+}
+
+void install_handler() {
+	stack_t ss;
+	ss.ss_sp = model_malloc(SIGSTACKSIZE);
+	ss.ss_size = SIGSTACKSIZE;
+	ss.ss_flags = 0;
+	sigaltstack(&ss, NULL);
+	struct sigaction sa;
+	sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART | SA_ONSTACK;
+	sigemptyset(&sa.sa_mask);
+	sa.sa_sigaction = mprot_handle_pf;
+
+	if (sigaction(SIGSEGV, &sa, NULL) == -1) {
+		perror("sigaction(SIGSEGV)");
+		exit(EXIT_FAILURE);
+	}
+
+}
+
 /** @brief Constructor */
 ModelChecker::ModelChecker() :
 	/* Initialize default scheduler */
 	params(),
-	restart_flag(false),
 	scheduler(new Scheduler()),
 	history(new ModelHistory()),
 	execution(new ModelExecution(this, scheduler)),
@@ -55,8 +85,7 @@ ModelChecker::ModelChecker() :
 	parse_options(&params);
 	initRaceDetector();
 	/* Configure output redirection for the model-checker */
-	redirect_output();
-	install_trace_analyses(get_execution());
+	install_handler();
 }
 
 /** @brief Destructor */
@@ -159,7 +188,7 @@ void ModelChecker::assert_user_bug(const char *msg)
 {
 	/* If feasible bug, bail out now */
 	assert_bug(msg);
-	switch_to_master(NULL);
+	switch_thread(NULL);
 }
 
 /** @brief Print bug report listing for this execution (if any bugs exist) */
@@ -237,7 +266,7 @@ void ModelChecker::print_execution(bool printbugs) const
  * @return If there are more executions to explore, return true. Otherwise,
  * return false.
  */
-bool ModelChecker::next_execution()
+void ModelChecker::finish_execution(bool more_executions)
 {
 	DBG();
 	/* Is this execution a feasible execution that's worth bug-checking? */
@@ -259,15 +288,11 @@ bool ModelChecker::next_execution()
 	else
 		clear_program_output();
 
-	if (restart_flag) {
-		do_restart();
-		return true;
-	}
-// test code
 	execution_number ++;
-	reset_to_initial_state();
 	history->set_new_exec_flag();
-	return false;
+
+	if (more_executions)
+		reset_to_initial_state();
 }
 
 /** @brief Run trace analyses on complete trace */
@@ -296,31 +321,134 @@ Thread * ModelChecker::get_thread(const ModelAction *act) const
 	return execution->get_thread(act);
 }
 
-/**
- * Switch from a model-checker context to a user-thread context. This is the
- * complement of ModelChecker::switch_to_master and must be called from the
- * model-checker context
- *
- * @param thread The user-thread to switch to
- */
-void ModelChecker::switch_from_master(Thread *thread)
+void ModelChecker::startRunExecution(Thread *old) {
+	while (true) {
+		if (params.traceminsize != 0 &&
+				execution->get_curr_seq_num() > checkfree) {
+			checkfree += params.checkthreshold;
+			execution->collectActions();
+		}
+
+		thread_chosen = false;
+		curr_thread_num = 1;
+
+		Thread *thr = getNextThread();
+		if (thr != nullptr) {
+			scheduler->set_current_thread(thr);
+
+			if (Thread::swap(old, thr) < 0) {
+				perror("swap threads");
+				exit(EXIT_FAILURE);
+			}
+			return;
+		}
+
+		if (execution->has_asserted()) {
+			finishRunExecution(old);
+			return;
+		}
+		if (!chosen_thread)
+			chosen_thread = get_next_thread();
+		if (!chosen_thread || chosen_thread->is_model_thread()) {
+			finishRunExecution(old);
+			return;
+		}
+		if (chosen_thread->just_woken_up()) {
+			chosen_thread->set_wakeup_state(false);
+			chosen_thread->set_pending(NULL);
+			chosen_thread = NULL;
+			// Allow this thread to stash the next pending action
+			continue;
+		}
+
+		/* Consume the next action for a Thread */
+		consumeAction();
+
+		if (should_terminate_execution()) {
+			finishRunExecution(old);
+			return;
+		}
+	}
+}
+
+Thread* ModelChecker::getNextThread()
 {
-	scheduler->set_current_thread(thread);
-	Thread::swap(&system_context, thread);
+	Thread *nextThread = nullptr;
+	for (unsigned int i = curr_thread_num;i < get_num_threads();i++) {
+		thread_id_t tid = int_to_id(i);
+		Thread *thr = get_thread(tid);
+
+		if (!thr->is_complete() && !thr->get_pending()) {
+			curr_thread_num = i;
+			nextThread = thr;
+			break;
+		}
+
+		/* Don't schedule threads which should be disabled */
+		ModelAction *act = thr->get_pending();
+		if (act && execution->is_enabled(thr) && !execution->check_action_enabled(act)) {
+			scheduler->sleep(thr);
+		}
+		chooseThread(act, thr);
+	}
+	return nextThread;
 }
 
-/**
- * Switch from a user-context to the "master thread" context (a.k.a. system
- * context). This switch is made with the intention of exploring a particular
- * model-checking action (described by a ModelAction object). Must be called
- * from a user-thread context.
- *
- * @param act The current action that will be explored. May be NULL only if
- * trace is exiting via an assertion (see ModelExecution::set_assert and
- * ModelExecution::has_asserted).
- * @return Return the value returned by the current action
- */
-uint64_t ModelChecker::switch_to_master(ModelAction *act)
+/* Swap back to system_context and terminate this execution */
+void ModelChecker::finishRunExecution(Thread *old)
+{
+	scheduler->set_current_thread(NULL);
+
+	/** If we have more executions, we won't make it past this call. */
+	finish_execution(execution_number < params.maxexecutions);
+
+
+	/** We finished the final execution.  Print stuff and exit. */
+	model_print("******* Model-checking complete: *******\n");
+	print_stats();
+
+	/* Have the trace analyses dump their output. */
+	for (unsigned int i = 0;i < trace_analyses.size();i++)
+		trace_analyses[i]->finish();
+
+	/* unlink tmp file created by last child process */
+	char filename[256];
+	snprintf_(filename, sizeof(filename), "C11FuzzerTmp%d", getpid());
+	unlink(filename);
+
+	/* Exit. */
+	_Exit(0);
+}
+
+void ModelChecker::consumeAction()
+{
+	ModelAction *curr = chosen_thread->get_pending();
+	chosen_thread->set_pending(NULL);
+	chosen_thread = execution->take_step(curr);
+}
+
+/* Allow pending relaxed/release stores or thread actions to perform first */
+void ModelChecker::chooseThread(ModelAction *act, Thread *thr)
+{
+	if (!thread_chosen && act && execution->is_enabled(thr) && (thr->get_state() != THREAD_BLOCKED) ) {
+		if (act->is_write()) {
+			std::memory_order order = act->get_mo();
+			if (order == std::memory_order_relaxed || \
+					order == std::memory_order_release) {
+				chosen_thread = thr;
+				thread_chosen = true;
+			}
+		} else if (act->get_type() == THREAD_CREATE || \
+							 act->get_type() == PTHREAD_CREATE || \
+							 act->get_type() == THREAD_START || \
+							 act->get_type() == THREAD_FINISH) {
+			chosen_thread = thr;
+			thread_chosen = true;
+		}
+	}
+}
+
+uint64_t ModelChecker::switch_thread(ModelAction *act)
 {
 	if (modellock) {
 		static bool fork_message_printed = false;
@@ -334,7 +462,8 @@ uint64_t ModelChecker::switch_to_master(ModelAction *act)
 	}
 	DBG();
 	Thread *old = thread_current();
-	scheduler->set_current_thread(NULL);
+	old->set_state(THREAD_READY);
+
 	ASSERT(!old->get_pending());
 
 	if (inspect_plugin != NULL) {
@@ -342,21 +471,72 @@ uint64_t ModelChecker::switch_to_master(ModelAction *act)
 	}
 
 	old->set_pending(act);
-	if (Thread::swap(old, &system_context) < 0) {
-		perror("swap threads");
-		exit(EXIT_FAILURE);
+
+	if (old->is_waiting_on(old))
+		assert_bug("Deadlock detected (thread %u)", curr_thread_num);
+
+	if (act && execution->is_enabled(old) && !execution->check_action_enabled(act)) {
+		scheduler->sleep(old);
 	}
+	chooseThread(act, old);
+
+	curr_thread_num++;
+	Thread* next = getNextThread();
+	if (next != nullptr) {
+		scheduler->set_current_thread(next);
+		if (Thread::swap(old, next) < 0) {
+			perror("swap threads");
+			exit(EXIT_FAILURE);
+		}
+	} else
+		handleChosenThread(old);
+
 	return old->get_return_value();
 }
 
-static void runChecker() {
-	model->run();
-	delete model;
+void ModelChecker::handleChosenThread(Thread *old)
+{
+	if (execution->has_asserted()) {
+		finishRunExecution(old);
+		return;
+	}
+	if (!chosen_thread)
+		chosen_thread = get_next_thread();
+	if (!chosen_thread || chosen_thread->is_model_thread()) {
+		finishRunExecution(old);
+		return;
+	}
+	if (chosen_thread->just_woken_up()) {
+		chosen_thread->set_wakeup_state(false);
+		chosen_thread->set_pending(NULL);
+		chosen_thread = NULL;
+		// Allow this thread to stash the next pending action
+		startRunExecution(old);
+		return;
+	}
+
+	// Consume the next action for a Thread
+	consumeAction();
+
+	if (should_terminate_execution()) {
+		finishRunExecution(old);
+		return;
+	} else
+		startRunExecution(old);
 }
 
 void ModelChecker::startChecker() {
-	startExecution(get_system_context(), runChecker);
+	startExecution();
+	//Need to initial random number generator state to avoid resets on rollback
+	initstate(423121, random_state, sizeof(random_state));
+
 	snapshot = take_snapshot();
+
+	//reset random number generator state
+	setstate(random_state);
+
+	install_trace_analyses(get_execution());
+	redirect_output();
 	initMainThread();
 }
 
@@ -370,122 +550,3 @@ bool ModelChecker::should_terminate_execution()
 	}
 	return false;
 }
-
-/** @brief Restart ModelChecker upon returning to the run loop of the
- *	model checker. */
-void ModelChecker::restart()
-{
-	restart_flag = true;
-}
-
-void ModelChecker::do_restart()
-{
-	restart_flag = false;
-	reset_to_initial_state();
-	memset(&stats,0,sizeof(struct execution_stats));
-	execution_number = 1;
-}
-
-/** @brief Run ModelChecker for the user program */
-void ModelChecker::run()
-{
-	//Need to initial random number generator state to avoid resets on rollback
-	char random_state[256];
-	initstate(423121, random_state, sizeof(random_state));
-	modelclock_t checkfree = params.checkthreshold;
-	for(int exec = 0;exec < params.maxexecutions;exec++) {
-		Thread * t = init_thread;
-
-		do {
-			/* Check whether we need to free model actions. */
-
-			if (params.traceminsize != 0 &&
-					execution->get_curr_seq_num() > checkfree) {
-				checkfree += params.checkthreshold;
-				execution->collectActions();
-			}
-
-			/*
-			 * Stash next pending action(s) for thread(s). There
-			 * should only need to stash one thread's action--the
-			 * thread which just took a step--plus the first step
-			 * for any newly-created thread
-			 */
-			for (unsigned int i = 0;i < get_num_threads();i++) {
-				thread_id_t tid = int_to_id(i);
-				Thread *thr = get_thread(tid);
-				if (!thr->is_model_thread() && !thr->is_complete() && !thr->get_pending()) {
-					switch_from_master(thr);
-					if (thr->is_waiting_on(thr))
-						assert_bug("Deadlock detected (thread %u)", i);
-				}
-			}
-
-			/* Don't schedule threads which should be disabled */
-			for (unsigned int i = 0;i < get_num_threads();i++) {
-				Thread *th = get_thread(int_to_id(i));
-				ModelAction *act = th->get_pending();
-				if (act && execution->is_enabled(th) && !execution->check_action_enabled(act)) {
-					scheduler->sleep(th);
-				}
-			}
-
-			for (unsigned int i = 1;i < get_num_threads();i++) {
-				Thread *th = get_thread(int_to_id(i));
-				ModelAction *act = th->get_pending();
-				if (act && execution->is_enabled(th) && (th->get_state() != THREAD_BLOCKED) ) {
-					if (act->is_write()) {
-						std::memory_order order = act->get_mo();
-						if (order == std::memory_order_relaxed || \
-								order == std::memory_order_release) {
-							t = th;
-							break;
-						}
-					} else if (act->get_type() == THREAD_CREATE || \
-										 act->get_type() == PTHREAD_CREATE || \
-										 act->get_type() == THREAD_START || \
-										 act->get_type() == THREAD_FINISH) {
-						t = th;
-						break;
-					}
-				}
-			}
-
-			/* Catch assertions from prior take_step or from
-			* between-ModelAction bugs (e.g., data races) */
-
-			if (execution->has_asserted())
-				break;
-			if (!t)
-				t = get_next_thread();
-			if (!t || t->is_model_thread())
-				break;
-			if (t->just_woken_up()) {
-				t->set_wakeup_state(false);
-				t->set_pending(NULL);
-				t = NULL;
-				continue;	// Allow this thread to stash the next pending action
-			}
-
-			/* Consume the next action for a Thread */
-			ModelAction *curr = t->get_pending();
-			t->set_pending(NULL);
-			t = execution->take_step(curr);
-		} while (!should_terminate_execution());
-		next_execution();
-		//restore random number generator state after rollback
-		setstate(random_state);
-	}
-
-	model_print("******* Model-checking complete: *******\n");
-	print_stats();
-
-	/* Have the trace analyses dump their output. */
-	for (unsigned int i = 0;i < trace_analyses.size();i++)
-		trace_analyses[i]->finish();
-
-	/* unlink tmp file created by last child process */
-	char filename[256];
-	snprintf_(filename, sizeof(filename), "C11FuzzerTmp%d", getpid());
-	unlink(filename);
-}