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