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
  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
  83         ASSERT(rf_set->size() != 0);
  84         int random_index = random() % rf_set->size();
  85
  86         return random_index;
  87 }
  88
  89 /* For children of curr_pred that matches read_inst.
  90  * If any store in rf_set satisfies the a child's predicate,
  91  * increment the store visibility count for it.
  92  *
  93  * @return False if no child matches read_inst
  94  */
  95 bool NewFuzzer::check_store_visibility(Predicate * curr_pred, FuncInst * read_inst,
  96                                                                                                                                                          inst_act_map_t * inst_act_map, SnapVector<ModelAction *> * rf_set)
  97 {
  98         available_branches_tmp_storage.clear();
  99
 100         ASSERT(!rf_set->empty());
 101         if (curr_pred == NULL || read_inst == NULL)
 102                 return false;
 103
 104         ModelVector<Predicate *> * children = curr_pred->get_children();
 105         bool any_child_match = false;
 106
 107         /* Iterate over all predicate children */
 108         for (uint i = 0;i < children->size();i++) {
 109                 Predicate * branch = (*children)[i];
 110
 111                 /* The children predicates may have different FuncInsts */
 112                 if (branch->get_func_inst() == read_inst) {
 113                         PredExprSet * pred_expressions = branch->get_pred_expressions();
 114                         any_child_match = true;
 115
 116                         /* Do not check unset predicates */
 117                         if (pred_expressions->isEmpty()) {
 118                                 available_branches_tmp_storage.push_back(branch);
 119                                 continue;
 120                         }
 121
 122                         branch->incr_total_checking_count();
 123
 124                         /* Iterate over all write actions */
 125                         for (uint j = 0;j < rf_set->size();j++) {
 126                                 ModelAction * write_act = (*rf_set)[j];
 127                                 uint64_t write_val = write_act->get_write_value();
 128                                 bool dummy = true;
 129                                 bool satisfy_predicate = check_predicate_expressions(pred_expressions, inst_act_map, write_val, &dummy);
 130
 131                                 /* If one write value satisfies the predicate, go to check the next predicate */
 132                                 if (satisfy_predicate) {
 133                                         branch->incr_store_visible_count();
 134                                         available_branches_tmp_storage.push_back(branch);
 135                                         break;
 136                                 }
 137                         }
 138                 }
 139         }
 140
 141         return any_child_match;
 142 }
 143
 144 /* Select a random branch from the children of curr_pred
 145  * @return The selected branch
 146  */
 147 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
 148 {
 149         int thread_id = id_to_int(tid);
 150         if ( thrd_selected_child_branch.size() <= (uint) thread_id)
 151                 thrd_selected_child_branch.resize(thread_id + 1);
 152
 153         if (curr_pred == NULL || read_inst == NULL) {
 154                 thrd_selected_child_branch[thread_id] = NULL;
 155                 return NULL;
 156         }
 157
 158         // predicate children have not been generated
 159         if (available_branches_tmp_storage.size() == 0) {
 160                 thrd_selected_child_branch[thread_id] = NULL;
 161                 return NULL;
 162         }
 163
 164         int index = choose_index(&available_branches_tmp_storage);
 165         Predicate * random_branch = available_branches_tmp_storage[ index ];
 166         thrd_selected_child_branch[thread_id] = random_branch;
 167
 168         return random_branch;
 169 }
 170
 171 /**
 172  * @brief Select a branch from the given predicate branch
 173  */
 174 int NewFuzzer::choose_index(SnapVector<Predicate *> * branches)
 175 {
 176         return random() % branches->size();
 177 }
 178
 179 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
 180 {
 181         int thread_id = id_to_int(tid);
 182         if (thrd_selected_child_branch.size() <= (uint) thread_id)
 183                 return NULL;
 184
 185         return thrd_selected_child_branch[thread_id];
 186 }
 187
 188 /* Remove writes from the rf_set that do not satisfie the selected predicate,
 189  * and store them in thrd_pruned_writes
 190  *
 191  * @return true if rf_set is pruned
 192  */
 193 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
 194                                                                                                                  SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
 195 {
 196         if (pred == NULL)
 197                 return false;
 198
 199         PredExprSet * pred_expressions = pred->get_pred_expressions();
 200         if (pred_expressions->getSize() == 0)   // unset predicates
 201                 return false;
 202
 203         int thread_id = id_to_int(tid);
 204         uint old_size = thrd_pruned_writes.size();
 205         if (thrd_pruned_writes.size() <= (uint) thread_id) {
 206                 uint new_size = thread_id + 1;
 207                 thrd_pruned_writes.resize(new_size);
 208                 for (uint i = old_size;i < new_size;i++)
 209                         thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
 210         }
 211         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
 212         pruned_writes->clear(); // clear the old pruned_writes set
 213
 214         bool pruned = false;
 215         uint index = 0;
 216
 217         while ( index < rf_set->size() ) {
 218                 ModelAction * write_act = (*rf_set)[index];
 219                 uint64_t write_val = write_act->get_write_value();
 220                 bool no_predicate = false;
 221                 bool satisfy_predicate = check_predicate_expressions(pred_expressions, inst_act_map, write_val, &no_predicate);
 222
 223                 if (no_predicate)
 224                         return false;
 225
 226                 if (!satisfy_predicate) {
 227                         ASSERT(rf_set != NULL);
 228                         (*rf_set)[index] = rf_set->back();
 229                         rf_set->pop_back();
 230                         pruned_writes->push_back(write_act);
 231                         pruned = true;
 232                 } else
 233                         index++;
 234         }
 235
 236         return pruned;
 237 }
 238
 239 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate.
 240  *
 241  * @param thread A thread whose last action is a read
 242  */
 243 void NewFuzzer::conditional_sleep(Thread * thread)
 244 {
 245         int index = paused_thread_list.size();
 246
 247         model->getScheduler()->add_sleep(thread);
 248         paused_thread_list.push_back(thread);
 249         paused_thread_table.put(thread, index); // Update table
 250
 251         /* Add the waiting condition to ModelHistory */
 252         ModelAction * read = thread->get_pending();
 253         thread_id_t tid = thread->get_id();
 254         FuncNode * func_node = history->get_curr_func_node(tid);
 255         inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
 256
 257         Predicate * selected_branch = get_selected_child_branch(tid);
 258         ConcretePredicate * concrete = selected_branch->evaluate(inst_act_map, tid);
 259         concrete->set_location(read->get_location());
 260
 261         history->add_waiting_write(concrete);
 262         /* history->add_waiting_thread is already called in find_threads */
 263 }
 264
 265 bool NewFuzzer::has_paused_threads()
 266 {
 267         return paused_thread_list.size() != 0;
 268 }
 269
 270 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
 271 {
 272         if (numthreads == 0 && has_paused_threads()) {
 273                 wake_up_paused_threads(threadlist, &numthreads);
 274                 //model_print("list size: %d, active t id: %d\n", numthreads, threadlist[0]);
 275         }
 276
 277         int random_index = random() % numthreads;
 278         int thread = threadlist[random_index];
 279         thread_id_t curr_tid = int_to_id(thread);
 280         return execution->get_thread(curr_tid);
 281 }
 282
 283 /* Force waking up one of threads paused by Fuzzer, because otherwise
 284  * the Fuzzer is not making progress
 285  */
 286 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
 287 {
 288         int random_index = random() % paused_thread_list.size();
 289         Thread * thread = paused_thread_list[random_index];
 290         model->getScheduler()->remove_sleep(thread);
 291
 292         Thread * last_thread = paused_thread_list.back();
 293         paused_thread_list[random_index] = last_thread;
 294         paused_thread_list.pop_back();
 295         paused_thread_table.put(last_thread, random_index);     // Update table
 296         paused_thread_table.remove(thread);
 297
 298         thread_id_t tid = thread->get_id();
 299         history->remove_waiting_write(tid);
 300         history->remove_waiting_thread(tid);
 301
 302         threadlist[*numthreads] = tid;
 303         (*numthreads)++;
 304
 305 /*--
 306         Predicate * selected_branch = get_selected_child_branch(tid);
 307         update_predicate_score(selected_branch, SLEEP_FAIL_TYPE3);
 308  */
 309
 310         model_print("thread %d is woken up\n", tid);
 311 }
 312
 313 /* Wake up conditional sleeping threads if the desired write is available */
 314 void NewFuzzer::notify_paused_thread(Thread * thread)
 315 {
 316         ASSERT(paused_thread_table.contains(thread));
 317
 318         int index = paused_thread_table.get(thread);
 319         model->getScheduler()->remove_sleep(thread);
 320
 321         Thread * last_thread = paused_thread_list.back();
 322         paused_thread_list[index] = last_thread;
 323         paused_thread_list.pop_back();
 324         paused_thread_table.put(last_thread, index);    // Update table
 325         paused_thread_table.remove(thread);
 326
 327         thread_id_t tid = thread->get_id();
 328         history->remove_waiting_write(tid);
 329         history->remove_waiting_thread(tid);
 330
 331 /*--
 332         Predicate * selected_branch = get_selected_child_branch(tid);
 333         update_predicate_score(selected_branch, SLEEP_SUCCESS);
 334  */
 335
 336         model_print("** thread %d is woken up\n", tid);
 337 }
 338
 339 /* Find threads that may write values that the pending read action is waiting for.
 340  * Side effect: waiting thread related info are stored in dist_info_vec
 341  *
 342  * @return True if any thread is found
 343  */
 344 bool NewFuzzer::find_threads(ModelAction * pending_read)
 345 {
 346         ASSERT(pending_read->is_read());
 347
 348         void * location = pending_read->get_location();
 349         thread_id_t self_id = pending_read->get_tid();
 350         bool finds_waiting_for = false;
 351
 352         SnapVector<FuncNode *> * func_node_list = history->getWrFuncNodes(location);
 353         for (uint i = 0;i < func_node_list->size();i++) {
 354                 FuncNode * target_node = (*func_node_list)[i];
 355                 for (uint i = 1;i < execution->get_num_threads();i++) {
 356                         thread_id_t tid = int_to_id(i);
 357                         if (tid == self_id)
 358                                 continue;
 359
 360                         FuncNode * node = history->get_curr_func_node(tid);
 361                         /* It is possible that thread tid is not in any FuncNode */
 362                         if (node == NULL)
 363                                 continue;
 364
 365                         int distance = node->compute_distance(target_node);
 366                         if (distance != -1) {
 367                                 finds_waiting_for = true;
 368                                 //model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
 369
 370                                 dist_info_vec.push_back(node_dist_info(tid, target_node, distance));
 371                         }
 372                 }
 373         }
 374
 375         return finds_waiting_for;
 376 }
 377
 378 bool NewFuzzer::check_predicate_expressions(PredExprSet * pred_expressions,
 379                                                                                                                                                                                 inst_act_map_t * inst_act_map, uint64_t write_val, bool * no_predicate)
 380 {
 381         bool satisfy_predicate = true;
 382
 383         PredExprSetIter * pred_expr_it = pred_expressions->iterator();
 384         while (pred_expr_it->hasNext()) {
 385                 struct pred_expr * expression = pred_expr_it->next();
 386                 bool equality;
 387
 388                 switch (expression->token) {
 389                 case NOPREDICATE:
 390                         *no_predicate = true;
 391                         break;
 392                 case EQUALITY:
 393                         FuncInst * to_be_compared;
 394                         ModelAction * last_act;
 395                         uint64_t last_read;
 396
 397                         to_be_compared = expression->func_inst;
 398                         last_act = inst_act_map->get(to_be_compared);
 399                         last_read = last_act->get_reads_from_value();
 400
 401                         equality = (write_val == last_read);
 402                         if (equality != expression->value)
 403                                 satisfy_predicate = false;
 404                         break;
 405                 case NULLITY:
 406                         // TODO: implement likely to be null
 407                         equality = ((void*) (write_val & 0xffffffff) == NULL);
 408                         if (equality != expression->value)
 409                                 satisfy_predicate = false;
 410                         break;
 411                 default:
 412                         model_print("unknown predicate token\n");
 413                         break;
 414                 }
 415
 416                 if (!satisfy_predicate)
 417                         break;
 418         }
 419
 420         return satisfy_predicate;
 421 }
 422
 423 bool NewFuzzer::shouldWait(const ModelAction * act)
 424 {
 425         return random() & 1;
 426 }