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