newfuzzer.cc

   1 #include "newfuzzer.h"
   2 #include "threads-model.h"
   3 #include "action.h"
   4 #include "history.h"
   5 #include "funcnode.h"
   6 #include "funcinst.h"
   7 #include "concretepredicate.h"
   8 #include "waitobj.h"
   9
  10 #include "model.h"
  11 #include "schedule.h"
  12 #include "execution.h"
  13
  14 NewFuzzer::NewFuzzer() :
  15         thrd_last_read_act(),
  16         thrd_last_func_inst(),
  17         available_branches_tmp_storage(),
  18         thrd_selected_child_branch(),
  19         thrd_pruned_writes(),
  20         paused_thread_list(),
  21         paused_thread_table(128),
  22         failed_predicates(32),
  23         dist_info_vec()
  24 {}
  25
  26 /**
  27  * @brief Register the ModelHistory and ModelExecution engine
  28  */
  29 void NewFuzzer::register_engine(ModelChecker *_model, ModelExecution *execution)
  30 {
  31         this->history = _model->get_history();
  32         this->execution = execution;
  33 }
  34
  35 int NewFuzzer::selectWrite(ModelAction *read, SnapVector<ModelAction *> * rf_set)
  36 {
  37 //      return random() % rf_set->size();
  38
  39         thread_id_t tid = read->get_tid();
  40         int thread_id = id_to_int(tid);
  41
  42         if (thrd_last_read_act.size() <= (uint) thread_id) {
  43                 thrd_last_read_act.resize(thread_id + 1);
  44                 thrd_last_func_inst.resize(thread_id + 1);
  45         }
  46
  47         // A new read action is encountered, select a random child branch of current predicate
  48         if (read != thrd_last_read_act[thread_id]) {
  49                 FuncNode * func_node = history->get_curr_func_node(tid);
  50                 Predicate * curr_pred = func_node->get_predicate_tree_position(tid);
  51                 FuncInst * read_inst = func_node->get_inst(read);
  52
  53                 int index = func_node->get_recursion_depth(tid);
  54                 uint32_t marker = func_node->get_marker(tid);
  55
  56                 if (curr_pred != NULL)  {
  57                         Predicate * selected_branch = NULL;
  58
  59                         if (check_branch_inst(curr_pred, read_inst, rf_set))
  60                                 selected_branch = selectBranch(tid, curr_pred, read_inst);
  61                         else {
  62                                 // no child of curr_pred matches read_inst, check back edges
  63                                 PredSet * back_edges = curr_pred->get_backedges();
  64                                 PredSetIter * it = back_edges->iterator();
  65
  66                                 while (it->hasNext()) {
  67                                         curr_pred = it->next();
  68                                         if (check_branch_inst(curr_pred, read_inst, rf_set)) {
  69                                                 selected_branch = selectBranch(tid, curr_pred, read_inst);
  70                                                 break;
  71                                         }
  72                                 }
  73
  74                                 delete it;
  75                         }
  76
  77                         prune_writes(tid, index, marker, selected_branch, rf_set);
  78                 }
  79
  80                 if (!failed_predicates.isEmpty())
  81                         failed_predicates.reset();
  82
  83                 thrd_last_read_act[thread_id] = read;
  84                 thrd_last_func_inst[thread_id] = read_inst;
  85         }
  86
  87         // The chosen branch fails, reselect new branches
  88         while ( rf_set->size() == 0 ) {
  89                 Predicate * selected_branch = get_selected_child_branch(tid);
  90                 FuncNode * func_node = history->get_curr_func_node(tid);
  91
  92                 int index = func_node->get_recursion_depth(tid);
  93                 uint32_t marker = func_node->get_marker(tid);
  94
  95                 // Add failed predicate to NewFuzzer and FuncNode
  96                 failed_predicates.put(selected_branch, true);
  97                 selected_branch->incr_fail_count();
  98
  99                 //model_print("the %d read action of thread %d at %p is unsuccessful\n", read->get_seq_number(), read_thread->get_id(), read->get_location());
 100
 101                 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
 102                 for (uint i = 0;i < pruned_writes->size();i++) {
 103                         rf_set->push_back( (*pruned_writes)[i] );
 104                 }
 105
 106                 // Reselect a predicate and prune writes
 107                 Predicate * curr_pred = selected_branch->get_parent();
 108                 FuncInst * read_inst = thrd_last_func_inst[thread_id];
 109                 selected_branch = selectBranch(tid, curr_pred, read_inst);
 110
 111                 prune_writes(tid, index, marker, selected_branch, rf_set);
 112
 113                 ASSERT(selected_branch);
 114         }
 115
 116         int random_index = random() % rf_set->size();
 117
 118         return random_index;
 119 }
 120
 121 /* Check if children of curr_pred match read_inst.
 122  * @return False if no child matches read_inst
 123  */
 124 bool NewFuzzer::check_branch_inst(Predicate * curr_pred, FuncInst * read_inst,
 125                                                                                                                                         SnapVector<ModelAction *> * rf_set)
 126 {
 127         available_branches_tmp_storage.clear();
 128
 129         ASSERT(!rf_set->empty());
 130         if (curr_pred == NULL || read_inst == NULL)
 131                 return false;
 132
 133         ModelVector<Predicate *> * children = curr_pred->get_children();
 134         bool any_child_match = false;
 135
 136         /* Iterate over all predicate children */
 137         for (uint i = 0;i < children->size();i++) {
 138                 Predicate * branch = (*children)[i];
 139
 140                 /* The children predicates may have different FuncInsts */
 141                 if (branch->get_func_inst() == read_inst) {
 142                         any_child_match = true;
 143                         branch->incr_total_checking_count();
 144                         available_branches_tmp_storage.push_back(branch);
 145                 }
 146         }
 147
 148         return any_child_match;
 149 }
 150
 151 /* Select a random branch from the children of curr_pred
 152  * @return The selected branch
 153  */
 154 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
 155 {
 156         int thread_id = id_to_int(tid);
 157         if ( thrd_selected_child_branch.size() <= (uint) thread_id)
 158                 thrd_selected_child_branch.resize(thread_id + 1);
 159
 160         if (curr_pred == NULL || read_inst == NULL) {
 161                 thrd_selected_child_branch[thread_id] = NULL;
 162                 return NULL;
 163         }
 164
 165         // predicate children have not been generated
 166         if (available_branches_tmp_storage.size() == 0) {
 167                 thrd_selected_child_branch[thread_id] = NULL;
 168                 return NULL;
 169         }
 170
 171         int index = choose_branch_index(&available_branches_tmp_storage);
 172         Predicate * selected_branch = available_branches_tmp_storage[ index ];
 173         thrd_selected_child_branch[thread_id] = selected_branch;
 174
 175         /* Remove the chosen branch from vec in case that this
 176          * branch fails and need to choose another one */
 177         available_branches_tmp_storage[index] = available_branches_tmp_storage.back();
 178         available_branches_tmp_storage.pop_back();
 179
 180         return selected_branch;
 181 }
 182
 183 /**
 184  * @brief Select a branch from the given predicate branch
 185  */
 186 int NewFuzzer::choose_branch_index(SnapVector<Predicate *> * branches)
 187 {
 188         if (branches->size() == 1)
 189                 return 0;
 190
 191         double total_weight = 0;
 192         SnapVector<double> weights;
 193         for (uint i = 0;i < branches->size();i++) {
 194                 Predicate * branch = (*branches)[i];
 195                 double weight = branch->get_weight();
 196                 total_weight += weight;
 197                 weights.push_back(weight);
 198         }
 199
 200         double prob = (double) random() / RAND_MAX;
 201         double prob_sum = 0;
 202         int index = 0;
 203
 204         for (uint i = 0;i < weights.size();i++) {
 205                 index = i;
 206                 prob_sum += (double) (weights[i] / total_weight);
 207                 if (prob_sum > prob) {
 208                         break;
 209                 }
 210         }
 211
 212         return index;
 213 //      return random() % branches->size();
 214 }
 215
 216 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
 217 {
 218         int thread_id = id_to_int(tid);
 219         if (thrd_selected_child_branch.size() <= (uint) thread_id)
 220                 return NULL;
 221
 222         return thrd_selected_child_branch[thread_id];
 223 }
 224
 225 /* Remove writes from the rf_set that do not satisfie the selected predicate,
 226  * and store them in thrd_pruned_writes
 227  *
 228  * @return true if rf_set is pruned
 229  */
 230 bool NewFuzzer::prune_writes(thread_id_t tid, int index, uint32_t marker,
 231                         Predicate * pred, SnapVector<ModelAction *> * rf_set)
 232 {
 233         if (pred == NULL)
 234                 return false;
 235
 236         PredExprSet * pred_expressions = pred->get_pred_expressions();
 237         if (pred_expressions->getSize() == 0)   // unset predicates
 238                 return false;
 239
 240         int thread_id = id_to_int(tid);
 241         uint old_size = thrd_pruned_writes.size();
 242         if (thrd_pruned_writes.size() <= (uint) thread_id) {
 243                 uint new_size = thread_id + 1;
 244                 thrd_pruned_writes.resize(new_size);
 245                 for (uint i = old_size;i < new_size;i++)
 246                         thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
 247         }
 248         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
 249         pruned_writes->clear(); // clear the old pruned_writes set
 250
 251         bool pruned = false;
 252         uint rf_index = 0;
 253
 254         while ( rf_index < rf_set->size() ) {
 255                 ModelAction * write_act = (*rf_set)[rf_index];
 256                 uint64_t write_val = write_act->get_write_value();
 257                 bool no_predicate = false;
 258                 bool satisfy_predicate = check_predicate_expressions(tid, index, marker, pred_expressions, write_val, &no_predicate);
 259
 260                 if (no_predicate)
 261                         return false;
 262
 263                 if (!satisfy_predicate) {
 264                         ASSERT(rf_set != NULL);
 265                         (*rf_set)[rf_index] = rf_set->back();
 266                         rf_set->pop_back();
 267                         pruned_writes->push_back(write_act);
 268                         pruned = true;
 269                 } else
 270                         rf_index++;
 271         }
 272
 273         return pruned;
 274 }
 275
 276 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate.
 277  *
 278  * @param thread A thread whose last action is a read
 279  */
 280 void NewFuzzer::conditional_sleep(Thread * thread)
 281 {
 282 /*
 283         int index = paused_thread_list.size();
 284
 285         model->getScheduler()->add_sleep(thread);
 286         paused_thread_list.push_back(thread);
 287         paused_thread_table.put(thread, index); // Update table
 288
 289         // Add the waiting condition to ModelHistory
 290         ModelAction * read = thread->get_pending();
 291         thread_id_t tid = thread->get_id();
 292         FuncNode * func_node = history->get_curr_func_node(tid);
 293 //      inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
 294
 295         Predicate * selected_branch = get_selected_child_branch(tid);
 296 //      ConcretePredicate * concrete = selected_branch->evaluate(inst_act_map, tid);
 297         concrete->set_location(read->get_location());
 298
 299         ASSERT(false);
 300
 301 //      history->add_waiting_write(concrete);
 302         // history->add_waiting_thread is already called in find_threads
 303 */
 304 }
 305
 306 bool NewFuzzer::has_paused_threads()
 307 {
 308         return paused_thread_list.size() != 0;
 309 }
 310
 311 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
 312 {
 313         if (numthreads == 0 && has_paused_threads()) {
 314                 wake_up_paused_threads(threadlist, &numthreads);
 315                 //model_print("list size: %d, active t id: %d\n", numthreads, threadlist[0]);
 316         }
 317
 318         int random_index = random() % numthreads;
 319         int thread = threadlist[random_index];
 320         thread_id_t curr_tid = int_to_id(thread);
 321         return execution->get_thread(curr_tid);
 322 }
 323
 324 /* Force waking up one of threads paused by Fuzzer, because otherwise
 325  * the Fuzzer is not making progress
 326  */
 327 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
 328 {
 329         int random_index = random() % paused_thread_list.size();
 330         Thread * thread = paused_thread_list[random_index];
 331         model->getScheduler()->remove_sleep(thread);
 332
 333         Thread * last_thread = paused_thread_list.back();
 334         paused_thread_list[random_index] = last_thread;
 335         paused_thread_list.pop_back();
 336         paused_thread_table.put(last_thread, random_index);     // Update table
 337         paused_thread_table.remove(thread);
 338
 339         thread_id_t tid = thread->get_id();
 340         history->remove_waiting_write(tid);
 341         history->remove_waiting_thread(tid);
 342
 343         threadlist[*numthreads] = tid;
 344         (*numthreads)++;
 345
 346 /*--
 347         Predicate * selected_branch = get_selected_child_branch(tid);
 348         update_predicate_score(selected_branch, SLEEP_FAIL_TYPE3);
 349  */
 350
 351         model_print("thread %d is woken up\n", tid);
 352 }
 353
 354 /* Wake up conditional sleeping threads if the desired write is available */
 355 void NewFuzzer::notify_paused_thread(Thread * thread)
 356 {
 357         ASSERT(paused_thread_table.contains(thread));
 358
 359         int index = paused_thread_table.get(thread);
 360         model->getScheduler()->remove_sleep(thread);
 361
 362         Thread * last_thread = paused_thread_list.back();
 363         paused_thread_list[index] = last_thread;
 364         paused_thread_list.pop_back();
 365         paused_thread_table.put(last_thread, index);    // Update table
 366         paused_thread_table.remove(thread);
 367
 368         thread_id_t tid = thread->get_id();
 369         history->remove_waiting_write(tid);
 370         history->remove_waiting_thread(tid);
 371
 372 /*--
 373         Predicate * selected_branch = get_selected_child_branch(tid);
 374         update_predicate_score(selected_branch, SLEEP_SUCCESS);
 375  */
 376
 377         model_print("** thread %d is woken up\n", tid);
 378 }
 379
 380 /* Find threads that may write values that the pending read action is waiting for.
 381  * Side effect: waiting thread related info are stored in dist_info_vec
 382  *
 383  * @return True if any thread is found
 384  */
 385 bool NewFuzzer::find_threads(ModelAction * pending_read)
 386 {
 387         ASSERT(pending_read->is_read());
 388
 389         void * location = pending_read->get_location();
 390         thread_id_t self_id = pending_read->get_tid();
 391         bool finds_waiting_for = false;
 392
 393         SnapVector<FuncNode *> * func_node_list = history->getWrFuncNodes(location);
 394         for (uint i = 0;i < func_node_list->size();i++) {
 395                 FuncNode * target_node = (*func_node_list)[i];
 396                 for (uint i = 1;i < execution->get_num_threads();i++) {
 397                         thread_id_t tid = int_to_id(i);
 398                         if (tid == self_id)
 399                                 continue;
 400
 401                         FuncNode * node = history->get_curr_func_node(tid);
 402                         /* It is possible that thread tid is not in any FuncNode */
 403                         if (node == NULL)
 404                                 continue;
 405
 406                         int distance = node->compute_distance(target_node);
 407                         if (distance != -1) {
 408                                 finds_waiting_for = true;
 409                                 //model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
 410
 411                                 dist_info_vec.push_back(node_dist_info(tid, target_node, distance));
 412                         }
 413                 }
 414         }
 415
 416         return finds_waiting_for;
 417 }
 418
 419 bool NewFuzzer::check_predicate_expressions(thread_id_t tid, int index, uint32_t marker,
 420                         PredExprSet * pred_expressions, uint64_t write_val, bool * no_predicate)
 421 {
 422         bool satisfy_predicate = true;
 423
 424         PredExprSetIter * pred_expr_it = pred_expressions->iterator();
 425         while (pred_expr_it->hasNext()) {
 426                 struct pred_expr * expression = pred_expr_it->next();
 427                 bool equality;
 428
 429                 switch (expression->token) {
 430                 case NOPREDICATE:
 431                         *no_predicate = true;
 432                         break;
 433                 case EQUALITY:
 434                         FuncInst * to_be_compared;
 435                         uint64_t last_read;
 436
 437                         to_be_compared = expression->func_inst;
 438                         last_read = to_be_compared->get_associated_read(tid, index, marker);
 439                         ASSERT(last_read != VALUE_NONE);
 440
 441                         equality = (write_val == last_read);
 442                         if (equality != expression->value)
 443                                 satisfy_predicate = false;
 444                         break;
 445                 case NULLITY:
 446                         // TODO: implement likely to be null
 447                         equality = ((void*) (write_val & 0xffffffff) == NULL);
 448                         if (equality != expression->value)
 449                                 satisfy_predicate = false;
 450                         break;
 451                 default:
 452                         model_print("unknown predicate token\n");
 453                         break;
 454                 }
 455
 456                 if (!satisfy_predicate)
 457                         break;
 458         }
 459
 460         delete pred_expr_it;
 461         return satisfy_predicate;
 462 }
 463
 464 bool NewFuzzer::shouldWait(const ModelAction * act)
 465 {
 466         return random() & 1;
 467 }