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