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