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