model.cc

   1 #include <stdio.h>
   2 #include <algorithm>
   3 #include <new>
   4 #include <stdarg.h>
   5 #include <string.h>
   6 #include <cstdlib>
   7
   8 #include "model.h"
   9 #include "action.h"
  10 #include "schedule.h"
  11 #include "snapshot-interface.h"
  12 #include "common.h"
  13 #include "datarace.h"
  14 #include "threads-model.h"
  15 #include "output.h"
  16 #include "traceanalysis.h"
  17 #include "execution.h"
  18 #include "history.h"
  19 #include "bugmessage.h"
  20 #include "params.h"
  21 #include "plugins.h"
  22
  23 ModelChecker *model = NULL;
  24 int inside_model = 0;
  25
  26 void placeholder(void *) {
  27         ASSERT(0);
  28 }
  29
  30 #include <signal.h>
  31
  32 #define SIGSTACKSIZE 65536
  33 static void mprot_handle_pf(int sig, siginfo_t *si, void *unused)
  34 {
  35         model_print("Segmentation fault at %p\n", si->si_addr);
  36         model_print("For debugging, place breakpoint at: %s:%d\n",
  37                                                         __FILE__, __LINE__);
  38         print_trace();  // Trace printing may cause dynamic memory allocation
  39         while(1)
  40                 ;
  41 }
  42
  43 void install_handler() {
  44         stack_t ss;
  45         ss.ss_sp = model_malloc(SIGSTACKSIZE);
  46         ss.ss_size = SIGSTACKSIZE;
  47         ss.ss_flags = 0;
  48         sigaltstack(&ss, NULL);
  49         struct sigaction sa;
  50         sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART | SA_ONSTACK;
  51         sigemptyset(&sa.sa_mask);
  52         sa.sa_sigaction = mprot_handle_pf;
  53
  54         if (sigaction(SIGSEGV, &sa, NULL) == -1) {
  55                 perror("sigaction(SIGSEGV)");
  56                 exit(EXIT_FAILURE);
  57         }
  58 }
  59
  60 void createModelIfNotExist() {
  61         if (!model) {
  62                 ENTER_MODEL_FLAG;
  63                 snapshot_system_init(100000);
  64                 model = new ModelChecker();
  65                 model->startChecker();
  66                 EXIT_MODEL_FLAG;
  67         }
  68 }
  69
  70 /** @brief Constructor */
  71 ModelChecker::ModelChecker() :
  72         /* Initialize default scheduler */
  73         params(),
  74         scheduler(new Scheduler()),
  75         history(new ModelHistory()),
  76         execution(new ModelExecution(this, scheduler)),
  77         execution_number(1),
  78         curr_thread_num(MAIN_THREAD_ID),
  79         trace_analyses(),
  80         inspect_plugin(NULL)
  81 {
  82         model_print("C11Tester\n"
  83                                                         "Copyright (c) 2013 and 2019 Regents of the University of California. All rights reserved.\n"
  84                                                         "Distributed under the GPLv2\n"
  85                                                         "Written by Weiyu Luo, Brian Norris, and Brian Demsky\n\n");
  86         init_memory_ops();
  87         real_memset(&stats,0,sizeof(struct execution_stats));
  88         init_thread = new Thread(execution->get_next_id(), (thrd_t *) model_malloc(sizeof(thrd_t)), &placeholder, NULL, NULL);
  89 #ifdef TLS
  90         init_thread->setTLS((char *)get_tls_addr());
  91 #endif
  92         execution->add_thread(init_thread);
  93         scheduler->set_current_thread(init_thread);
  94         register_plugins();
  95         execution->setParams(&params);
  96         param_defaults(&params);
  97         parse_options(&params);
  98         initRaceDetector();
  99         /* Configure output redirection for the model-checker */
 100         install_handler();
 101 }
 102
 103 /** @brief Destructor */
 104 ModelChecker::~ModelChecker()
 105 {
 106         delete scheduler;
 107 }
 108
 109 /** Method to set parameters */
 110 model_params * ModelChecker::getParams() {
 111         return &params;
 112 }
 113
 114 /**
 115  * Restores user program to initial state and resets all model-checker data
 116  * structures.
 117  */
 118 void ModelChecker::reset_to_initial_state()
 119 {
 120
 121         /**
 122          * FIXME: if we utilize partial rollback, we will need to free only
 123          * those pending actions which were NOT pending before the rollback
 124          * point
 125          */
 126         for (unsigned int i = 0;i < get_num_threads();i++)
 127                 delete get_thread(int_to_id(i))->get_pending();
 128
 129         snapshot_roll_back(snapshot);
 130 }
 131
 132 /** @return the number of user threads created during this execution */
 133 unsigned int ModelChecker::get_num_threads() const
 134 {
 135         return execution->get_num_threads();
 136 }
 137
 138 /**
 139  * Must be called from user-thread context (e.g., through the global
 140  * thread_current() interface)
 141  *
 142  * @return The currently executing Thread.
 143  */
 144 Thread * ModelChecker::get_current_thread() const
 145 {
 146         return scheduler->get_current_thread();
 147 }
 148
 149 /**
 150  * Must be called from user-thread context (e.g., through the global
 151  * thread_current_id() interface)
 152  *
 153  * @return The id of the currently executing Thread.
 154  */
 155 thread_id_t ModelChecker::get_current_thread_id() const
 156 {
 157         ASSERT(int_to_id(curr_thread_num) == get_current_thread()->get_id());
 158         return int_to_id(curr_thread_num);
 159 }
 160
 161 /**
 162  * @brief Choose the next thread to execute.
 163  *
 164  * This function chooses the next thread that should execute. It can enforce
 165  * execution replay/backtracking or, if the model-checker has no preference
 166  * regarding the next thread (i.e., when exploring a new execution ordering),
 167  * we defer to the scheduler.
 168  *
 169  * @return The next chosen thread to run, if any exist. Or else if the current
 170  * execution should terminate, return NULL.
 171  */
 172 Thread * ModelChecker::get_next_thread()
 173 {
 174
 175         /*
 176          * Have we completed exploring the preselected path? Then let the
 177          * scheduler decide
 178          */
 179         return scheduler->select_next_thread();
 180 }
 181
 182 /**
 183  * @brief Assert a bug in the executing program.
 184  *
 185  * Use this function to assert any sort of bug in the user program. If the
 186  * current trace is feasible (actually, a prefix of some feasible execution),
 187  * then this execution will be aborted, printing the appropriate message. If
 188  * the current trace is not yet feasible, the error message will be stashed and
 189  * printed if the execution ever becomes feasible.
 190  *
 191  * @param msg Descriptive message for the bug (do not include newline char)
 192  * @return True if bug is immediately-feasible
 193  */
 194 void ModelChecker::assert_bug(const char *msg, ...)
 195 {
 196         char str[800];
 197
 198         va_list ap;
 199         va_start(ap, msg);
 200         vsnprintf(str, sizeof(str), msg, ap);
 201         va_end(ap);
 202
 203         execution->assert_bug(str);
 204 }
 205
 206 /**
 207  * @brief Assert a bug in the executing program, asserted by a user thread
 208  * @see ModelChecker::assert_bug
 209  * @param msg Descriptive message for the bug (do not include newline char)
 210  */
 211 void ModelChecker::assert_user_bug(const char *msg)
 212 {
 213         /* If feasible bug, bail out now */
 214         assert_bug(msg);
 215         switch_thread(NULL);
 216 }
 217
 218 /** @brief Print bug report listing for this execution (if any bugs exist) */
 219 void ModelChecker::print_bugs() const
 220 {
 221         SnapVector<bug_message *> *bugs = execution->get_bugs();
 222
 223         model_print("Bug report: %zu bug%s detected\n",
 224                                                         bugs->size(),
 225                                                         bugs->size() > 1 ? "s" : "");
 226         for (unsigned int i = 0;i < bugs->size();i++)
 227                 (*bugs)[i] -> print();
 228 }
 229
 230 /**
 231  * @brief Record end-of-execution stats
 232  *
 233  * Must be run when exiting an execution. Records various stats.
 234  * @see struct execution_stats
 235  */
 236 void ModelChecker::record_stats()
 237 {
 238         stats.num_total ++;
 239         if (execution->have_bug_reports())
 240                 stats.num_buggy_executions ++;
 241         else if (execution->is_complete_execution())
 242                 stats.num_complete ++;
 243         else {
 244                 //All threads are sleeping
 245                 /**
 246                  * @todo We can violate this ASSERT() when fairness/sleep sets
 247                  * conflict to cause an execution to terminate, e.g. with:
 248                  * Scheduler: [0: disabled][1: disabled][2: sleep][3: current, enabled]
 249                  */
 250                 //ASSERT(scheduler->all_threads_sleeping());
 251         }
 252 }
 253
 254 /** @brief Print execution stats */
 255 void ModelChecker::print_stats() const
 256 {
 257         model_print("Number of complete, bug-free executions: %d\n", stats.num_complete);
 258         model_print("Number of buggy executions: %d\n", stats.num_buggy_executions);
 259         model_print("Total executions: %d\n", stats.num_total);
 260 }
 261
 262 /**
 263  * @brief End-of-exeuction print
 264  * @param printbugs Should any existing bugs be printed?
 265  */
 266 void ModelChecker::print_execution(bool printbugs) const
 267 {
 268         model_print("Program output from execution %d:\n",
 269                                                         get_execution_number());
 270         print_program_output();
 271
 272         if (params.verbose >= 3) {
 273                 print_stats();
 274         }
 275
 276         /* Don't print invalid bugs */
 277         if (printbugs && execution->have_bug_reports()) {
 278                 model_print("\n");
 279                 print_bugs();
 280         }
 281
 282         model_print("\n");
 283         execution->print_summary();
 284 }
 285
 286 /**
 287  * Queries the model-checker for more executions to explore and, if one
 288  * exists, resets the model-checker state to execute a new execution.
 289  *
 290  * @return If there are more executions to explore, return true. Otherwise,
 291  * return false.
 292  */
 293 void ModelChecker::finish_execution(bool more_executions)
 294 {
 295         DBG();
 296         /* Is this execution a feasible execution that's worth bug-checking? */
 297         bool complete = (execution->is_complete_execution() ||
 298                                                                          execution->have_bug_reports());
 299
 300         /* End-of-execution bug checks */
 301         if (complete) {
 302                 if (execution->is_deadlocked())
 303                         assert_bug("Deadlock detected");
 304
 305                 run_trace_analyses();
 306         }
 307
 308         record_stats();
 309         /* Output */
 310         if ( (complete && params.verbose) || params.verbose>1 || (complete && execution->have_bug_reports()))
 311                 print_execution(complete);
 312         else
 313                 clear_program_output();
 314
 315         execution_number ++;
 316         history->set_new_exec_flag();
 317
 318         if (more_executions)
 319                 reset_to_initial_state();
 320 }
 321
 322 /** @brief Run trace analyses on complete trace */
 323 void ModelChecker::run_trace_analyses() {
 324         for (unsigned int i = 0;i < trace_analyses.size();i ++)
 325                 trace_analyses[i] -> analyze(execution->get_action_trace());
 326 }
 327
 328 /**
 329  * @brief Get a Thread reference by its ID
 330  * @param tid The Thread's ID
 331  * @return A Thread reference
 332  */
 333 Thread * ModelChecker::get_thread(thread_id_t tid) const
 334 {
 335         return execution->get_thread(tid);
 336 }
 337
 338 /**
 339  * @brief Get a reference to the Thread in which a ModelAction was executed
 340  * @param act The ModelAction
 341  * @return A Thread reference
 342  */
 343 Thread * ModelChecker::get_thread(const ModelAction *act) const
 344 {
 345         return execution->get_thread(act);
 346 }
 347
 348 void ModelChecker::startRunExecution(Thread *old) {
 349         while (true) {
 350                 if (params.traceminsize != 0 &&
 351                                 execution->get_curr_seq_num() > checkfree) {
 352                         checkfree += params.checkthreshold;
 353                         execution->collectActions();
 354                 }
 355
 356                 curr_thread_num = MAIN_THREAD_ID;
 357                 Thread *thr = getNextThread(old);
 358                 if (thr != nullptr) {
 359                         scheduler->set_current_thread(thr);
 360                         EXIT_MODEL_FLAG;
 361                         if (Thread::swap(old, thr) < 0) {
 362                                 perror("swap threads");
 363                                 exit(EXIT_FAILURE);
 364                         }
 365                         return;
 366                 }
 367
 368                 if (!handleChosenThread(old)) {
 369                         return;
 370                 }
 371         }
 372 }
 373
 374 Thread* ModelChecker::getNextThread(Thread *old)
 375 {
 376         Thread *nextThread = nullptr;
 377         for (unsigned int i = curr_thread_num;i < get_num_threads();i++) {
 378                 thread_id_t tid = int_to_id(i);
 379                 Thread *thr = get_thread(tid);
 380
 381                 if (!thr->is_complete()) {
 382                         if (!thr->get_pending()) {
 383                                 curr_thread_num = i;
 384                                 nextThread = thr;
 385                                 break;
 386                         }
 387                 } else if (thr != old && !thr->is_freed()) {
 388                         thr->freeResources();
 389                 }
 390
 391                 ModelAction *act = thr->get_pending();
 392                 if (act && scheduler->is_enabled(tid)){
 393                         /* Don't schedule threads which should be disabled */
 394                         if (!execution->check_action_enabled(act)) {
 395                                 scheduler->sleep(thr);
 396                         }
 397
 398                         /* Allow pending relaxed/release stores or thread actions to perform first */
 399                         else if (!chosen_thread) {
 400                                 if (act->is_write()) {
 401                                         std::memory_order order = act->get_mo();
 402                                         if (order == std::memory_order_relaxed || \
 403                                                         order == std::memory_order_release) {
 404                                                 chosen_thread = thr;
 405                                         }
 406                                 } else if (act->get_type() == THREAD_CREATE || \
 407                                                                          act->get_type() == PTHREAD_CREATE || \
 408                                                                          act->get_type() == THREAD_START || \
 409                                                                          act->get_type() == THREAD_FINISH) {
 410                                         chosen_thread = thr;
 411                                 }
 412                         }
 413                 }
 414         }
 415         return nextThread;
 416 }
 417
 418 /* Swap back to system_context and terminate this execution */
 419 void ModelChecker::finishRunExecution(Thread *old)
 420 {
 421         scheduler->set_current_thread(NULL);
 422
 423         /** Reset curr_thread_num to initial value for next execution. */
 424         curr_thread_num = MAIN_THREAD_ID;
 425
 426         /** If we have more executions, we won't make it past this call. */
 427         finish_execution(execution_number < params.maxexecutions);
 428
 429
 430         /** We finished the final execution.  Print stuff and exit. */
 431         model_print("******* Model-checking complete: *******\n");
 432         print_stats();
 433
 434         /* Have the trace analyses dump their output. */
 435         for (unsigned int i = 0;i < trace_analyses.size();i++)
 436                 trace_analyses[i]->finish();
 437
 438         /* unlink tmp file created by last child process */
 439         char filename[256];
 440         snprintf_(filename, sizeof(filename), "C11FuzzerTmp%d", getpid());
 441         unlink(filename);
 442
 443         /* Exit. */
 444         _Exit(0);
 445 }
 446
 447 uint64_t ModelChecker::switch_thread(ModelAction *act)
 448 {
 449         if (modellock) {
 450                 static bool fork_message_printed = false;
 451
 452                 if (!fork_message_printed) {
 453                         model_print("Fork handler or dead thread trying to call into model checker...\n");
 454                         fork_message_printed = true;
 455                 }
 456                 delete act;
 457                 return 0;
 458         }
 459         ENTER_MODEL_FLAG;
 460
 461         DBG();
 462         Thread *old = thread_current();
 463         old->set_state(THREAD_READY);
 464
 465         ASSERT(!old->get_pending());
 466
 467         if (inspect_plugin != NULL) {
 468                 inspect_plugin->inspectModelAction(act);
 469         }
 470
 471         old->set_pending(act);
 472
 473         if (old->is_waiting_on(old))
 474                 assert_bug("Deadlock detected (thread %u)", curr_thread_num);
 475
 476         Thread* next = getNextThread(old);
 477         if (next != nullptr) {
 478                 scheduler->set_current_thread(next);
 479                 if (Thread::swap(old, next) < 0) {
 480                         perror("swap threads");
 481                         exit(EXIT_FAILURE);
 482                 }
 483         } else {
 484                 if (handleChosenThread(old)) {
 485                         startRunExecution(old);
 486                 }
 487         }
 488         return old->get_return_value();
 489 }
 490
 491 bool ModelChecker::handleChosenThread(Thread *old)
 492 {
 493         if (execution->has_asserted()) {
 494                 finishRunExecution(old);
 495                 return false;
 496         }
 497         if (!chosen_thread) {
 498                 chosen_thread = get_next_thread();
 499         }
 500         if (!chosen_thread) {
 501                 finishRunExecution(old);
 502                 return false;
 503         }
 504         if (chosen_thread->just_woken_up()) {
 505                 chosen_thread->set_wakeup_state(false);
 506                 chosen_thread->set_pending(NULL);
 507                 chosen_thread = NULL;
 508                 // Allow this thread to stash the next pending action
 509                 return true;
 510         }
 511
 512         // Consume the next action for a Thread
 513         ModelAction *curr = chosen_thread->get_pending();
 514         chosen_thread->set_pending(NULL);
 515         chosen_thread = execution->take_step(curr);
 516
 517         if (should_terminate_execution()) {
 518                 finishRunExecution(old);
 519                 return false;
 520         } else {
 521                 return true;
 522         }
 523 }
 524
 525 void ModelChecker::startChecker() {
 526         startExecution();
 527         //Need to initial random number generator state to avoid resets on rollback
 528         initstate(423121, random_state, sizeof(random_state));
 529
 530         snapshot = take_snapshot();
 531
 532         //reset random number generator state
 533         setstate(random_state);
 534
 535         install_trace_analyses(get_execution());
 536         redirect_output();
 537         initMainThread();
 538 }
 539
 540 bool ModelChecker::should_terminate_execution()
 541 {
 542         if (execution->have_bug_reports()) {
 543                 execution->set_assert();
 544                 return true;
 545         } else if (execution->isFinished()) {
 546                 return true;
 547         }
 548         return false;
 549 }