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