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