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         ASSERT(rf_set->size() != 0);
  86         int random_index = random() % rf_set->size();
  87
  88         return random_index;
  89 }
  90
  91 /* For children of curr_pred that matches read_inst.
  92  * If any store in rf_set satisfies the a child's predicate,
  93  * increment the store visibility count for it.
  94  *
  95  * @return False if no child matches read_inst
  96  */
  97 bool NewFuzzer::check_store_visibility(Predicate * curr_pred, FuncInst * read_inst,
  98 inst_act_map_t * inst_act_map, SnapVector<ModelAction *> * rf_set)
  99 {
 100         available_branches_tmp_storage.clear();
 101
 102         ASSERT(!rf_set->empty());
 103         if (curr_pred == NULL || read_inst == NULL)
 104                 return false;
 105
 106         ModelVector<Predicate *> * children = curr_pred->get_children();
 107         bool any_child_match = false;
 108
 109         /* Iterate over all predicate children */
 110         for (uint i = 0;i < children->size();i++) {
 111                 Predicate * branch = (*children)[i];
 112
 113                 /* The children predicates may have different FuncInsts */
 114                 if (branch->get_func_inst() == read_inst) {
 115                         PredExprSet * pred_expressions = branch->get_pred_expressions();
 116                         any_child_match = true;
 117
 118                         branch->incr_total_checking_count();
 119
 120                         if (pred_expressions->isEmpty()) {
 121                                 /* Do not check predicate expression of unset predicates */
 122                                 available_branches_tmp_storage.push_back(branch);
 123                                 branch->incr_store_visible_count();
 124                                 continue;
 125                         }
 126
 127                         /* Iterate over all write actions */
 128                         for (uint j = 0;j < rf_set->size();j++) {
 129                                 ModelAction * write_act = (*rf_set)[j];
 130                                 uint64_t write_val = write_act->get_write_value();
 131                                 bool dummy = true;
 132                                 bool satisfy_predicate = check_predicate_expressions(pred_expressions, inst_act_map, write_val, &dummy);
 133
 134                                 /* If one write value satisfies the predicate, go to check the next predicate */
 135                                 if (satisfy_predicate) {
 136                                         branch->incr_store_visible_count();
 137                                         available_branches_tmp_storage.push_back(branch);
 138                                         break;
 139                                 }
 140                         }
 141                 }
 142         }
 143
 144         return any_child_match;
 145 }
 146
 147 /* Select a random branch from the children of curr_pred
 148  * @return The selected branch
 149  */
 150 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
 151 {
 152         int thread_id = id_to_int(tid);
 153         if ( thrd_selected_child_branch.size() <= (uint) thread_id)
 154                 thrd_selected_child_branch.resize(thread_id + 1);
 155
 156         if (curr_pred == NULL || read_inst == NULL) {
 157                 thrd_selected_child_branch[thread_id] = NULL;
 158                 return NULL;
 159         }
 160
 161         // predicate children have not been generated
 162         if (available_branches_tmp_storage.size() == 0) {
 163                 thrd_selected_child_branch[thread_id] = NULL;
 164                 return NULL;
 165         }
 166
 167         int index = choose_index(&available_branches_tmp_storage);
 168         Predicate * random_branch = available_branches_tmp_storage[ index ];
 169         thrd_selected_child_branch[thread_id] = random_branch;
 170
 171         return random_branch;
 172 }
 173
 174 /**
 175  * @brief Select a branch from the given predicate branch
 176  */
 177 int NewFuzzer::choose_index(SnapVector<Predicate *> * branches)
 178 {
 179         return random() % branches->size();
 180 }
 181
 182 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
 183 {
 184         int thread_id = id_to_int(tid);
 185         if (thrd_selected_child_branch.size() <= (uint) thread_id)
 186                 return NULL;
 187
 188         return thrd_selected_child_branch[thread_id];
 189 }
 190
 191 /* Remove writes from the rf_set that do not satisfie the selected predicate,
 192  * and store them in thrd_pruned_writes
 193  *
 194  * @return true if rf_set is pruned
 195  */
 196 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
 197 SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
 198 {
 199         if (pred == NULL)
 200                 return false;
 201
 202         PredExprSet * pred_expressions = pred->get_pred_expressions();
 203         if (pred_expressions->getSize() == 0)   // unset predicates
 204                 return false;
 205
 206         int thread_id = id_to_int(tid);
 207         uint old_size = thrd_pruned_writes.size();
 208         if (thrd_pruned_writes.size() <= (uint) thread_id) {
 209                 uint new_size = thread_id + 1;
 210                 thrd_pruned_writes.resize(new_size);
 211                 for (uint i = old_size;i < new_size;i++)
 212                         thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
 213         }
 214         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
 215         pruned_writes->clear(); // clear the old pruned_writes set
 216
 217         bool pruned = false;
 218         uint index = 0;
 219
 220         while ( index < rf_set->size() ) {
 221                 ModelAction * write_act = (*rf_set)[index];
 222                 uint64_t write_val = write_act->get_write_value();
 223                 bool no_predicate = false;
 224                 bool satisfy_predicate = check_predicate_expressions(pred_expressions, inst_act_map, write_val, &no_predicate);
 225
 226                 if (no_predicate)
 227                         return false;
 228
 229                 if (!satisfy_predicate) {
 230                         ASSERT(rf_set != NULL);
 231                         (*rf_set)[index] = rf_set->back();
 232                         rf_set->pop_back();
 233                         pruned_writes->push_back(write_act);
 234                         pruned = true;
 235                 } else
 236                         index++;
 237         }
 238
 239         return pruned;
 240 }
 241
 242 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate.
 243  *
 244  * @param thread A thread whose last action is a read
 245  */
 246 void NewFuzzer::conditional_sleep(Thread * thread)
 247 {
 248         int index = paused_thread_list.size();
 249
 250         model->getScheduler()->add_sleep(thread);
 251         paused_thread_list.push_back(thread);
 252         paused_thread_table.put(thread, index); // Update table
 253
 254         /* Add the waiting condition to ModelHistory */
 255         ModelAction * read = thread->get_pending();
 256         thread_id_t tid = thread->get_id();
 257         FuncNode * func_node = history->get_curr_func_node(tid);
 258         inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
 259
 260         Predicate * selected_branch = get_selected_child_branch(tid);
 261         ConcretePredicate * concrete = selected_branch->evaluate(inst_act_map, tid);
 262         concrete->set_location(read->get_location());
 263
 264         history->add_waiting_write(concrete);
 265         /* history->add_waiting_thread is already called in find_threads */
 266 }
 267
 268 bool NewFuzzer::has_paused_threads()
 269 {
 270         return paused_thread_list.size() != 0;
 271 }
 272
 273 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
 274 {
 275         if (numthreads == 0 && has_paused_threads()) {
 276                 wake_up_paused_threads(threadlist, &numthreads);
 277                 //model_print("list size: %d, active t id: %d\n", numthreads, threadlist[0]);
 278         }
 279
 280         int random_index = random() % numthreads;
 281         int thread = threadlist[random_index];
 282         thread_id_t curr_tid = int_to_id(thread);
 283         return execution->get_thread(curr_tid);
 284 }
 285
 286 /* Force waking up one of threads paused by Fuzzer, because otherwise
 287  * the Fuzzer is not making progress
 288  */
 289 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
 290 {
 291         int random_index = random() % paused_thread_list.size();
 292         Thread * thread = paused_thread_list[random_index];
 293         model->getScheduler()->remove_sleep(thread);
 294
 295         Thread * last_thread = paused_thread_list.back();
 296         paused_thread_list[random_index] = last_thread;
 297         paused_thread_list.pop_back();
 298         paused_thread_table.put(last_thread, random_index);     // Update table
 299         paused_thread_table.remove(thread);
 300
 301         thread_id_t tid = thread->get_id();
 302         history->remove_waiting_write(tid);
 303         history->remove_waiting_thread(tid);
 304
 305         threadlist[*numthreads] = tid;
 306         (*numthreads)++;
 307
 308 /*--
 309         Predicate * selected_branch = get_selected_child_branch(tid);
 310         update_predicate_score(selected_branch, SLEEP_FAIL_TYPE3);
 311  */
 312
 313         model_print("thread %d is woken up\n", tid);
 314 }
 315
 316 /* Wake up conditional sleeping threads if the desired write is available */
 317 void NewFuzzer::notify_paused_thread(Thread * thread)
 318 {
 319         ASSERT(paused_thread_table.contains(thread));
 320
 321         int index = paused_thread_table.get(thread);
 322         model->getScheduler()->remove_sleep(thread);
 323
 324         Thread * last_thread = paused_thread_list.back();
 325         paused_thread_list[index] = last_thread;
 326         paused_thread_list.pop_back();
 327         paused_thread_table.put(last_thread, 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 /*--
 335         Predicate * selected_branch = get_selected_child_branch(tid);
 336         update_predicate_score(selected_branch, SLEEP_SUCCESS);
 337  */
 338
 339         model_print("** thread %d is woken up\n", tid);
 340 }
 341
 342 /* Find threads that may write values that the pending read action is waiting for.
 343  * Side effect: waiting thread related info are stored in dist_info_vec
 344  *
 345  * @return True if any thread is found
 346  */
 347 bool NewFuzzer::find_threads(ModelAction * pending_read)
 348 {
 349         ASSERT(pending_read->is_read());
 350
 351         void * location = pending_read->get_location();
 352         thread_id_t self_id = pending_read->get_tid();
 353         bool finds_waiting_for = false;
 354
 355         SnapVector<FuncNode *> * func_node_list = history->getWrFuncNodes(location);
 356         for (uint i = 0;i < func_node_list->size();i++) {
 357                 FuncNode * target_node = (*func_node_list)[i];
 358                 for (uint i = 1;i < execution->get_num_threads();i++) {
 359                         thread_id_t tid = int_to_id(i);
 360                         if (tid == self_id)
 361                                 continue;
 362
 363                         FuncNode * node = history->get_curr_func_node(tid);
 364                         /* It is possible that thread tid is not in any FuncNode */
 365                         if (node == NULL)
 366                                 continue;
 367
 368                         int distance = node->compute_distance(target_node);
 369                         if (distance != -1) {
 370                                 finds_waiting_for = true;
 371                                 //model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
 372
 373                                 dist_info_vec.push_back(node_dist_info(tid, target_node, distance));
 374                         }
 375                 }
 376         }
 377
 378         return finds_waiting_for;
 379 }
 380
 381 bool NewFuzzer::check_predicate_expressions(PredExprSet * pred_expressions,
 382 inst_act_map_t * inst_act_map, uint64_t write_val, bool * no_predicate)
 383 {
 384         bool satisfy_predicate = true;
 385
 386         PredExprSetIter * pred_expr_it = pred_expressions->iterator();
 387         while (pred_expr_it->hasNext()) {
 388                 struct pred_expr * expression = pred_expr_it->next();
 389                 bool equality;
 390
 391                 switch (expression->token) {
 392                         case NOPREDICATE:
 393                                 *no_predicate = true;
 394                                 break;
 395                         case EQUALITY:
 396                                 FuncInst * to_be_compared;
 397                                 ModelAction * last_act;
 398                                 uint64_t last_read;
 399
 400                                 to_be_compared = expression->func_inst;
 401                                 last_act = inst_act_map->get(to_be_compared);
 402                                 last_read = last_act->get_reads_from_value();
 403
 404                                 equality = (write_val == last_read);
 405                                 if (equality != expression->value)
 406                                         satisfy_predicate = false;
 407                                 break;
 408                         case NULLITY:
 409                                 // TODO: implement likely to be null
 410                                 equality = ((void*) (write_val & 0xffffffff) == NULL);
 411                                 if (equality != expression->value)
 412                                         satisfy_predicate = false;
 413                                 break;
 414                         default:
 415                                 model_print("unknown predicate token\n");
 416                                 break;
 417                 }
 418
 419                 if (!satisfy_predicate)
 420                         break;
 421         }
 422
 423         delete pred_expr_it;
 424         return satisfy_predicate;
 425 }
 426
 427 bool NewFuzzer::shouldWait(const ModelAction * act)
 428 {
 429         return random() & 1;
 430 }