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 "predicate.h"
   8 #include "concretepredicate.h"
   9 #include "waitobj.h"
  10
  11 #include "model.h"
  12 #include "schedule.h"
  13 #include "execution.h"
  14
  15 NewFuzzer::NewFuzzer() :
  16         thrd_last_read_act(),
  17         thrd_curr_pred(),
  18         thrd_selected_child_branch(),
  19         thrd_pruned_writes(),
  20         paused_thread_set(),
  21         paused_thread_table(128)
  22 {}
  23
  24 /**
  25  * @brief Register the ModelHistory and ModelExecution engine
  26  */
  27 void NewFuzzer::register_engine(ModelHistory * history, ModelExecution *execution)
  28 {
  29         this->history = history;
  30         this->execution = execution;
  31 }
  32
  33 int NewFuzzer::selectWrite(ModelAction *read, SnapVector<ModelAction *> * rf_set)
  34 {
  35 //      return random() % rf_set->size();
  36
  37         thread_id_t tid = read->get_tid();
  38         int thread_id = id_to_int(tid);
  39
  40         if (thrd_last_read_act.size() <= (uint) thread_id)
  41                 thrd_last_read_act.resize(thread_id + 1);
  42
  43         // A new read action is encountered, select a random child branch of current predicate
  44         if (read != thrd_last_read_act[thread_id]) {
  45                 thrd_last_read_act[thread_id] = read;
  46
  47                 FuncNode * func_node = history->get_curr_func_node(tid);
  48                 Predicate * curr_pred = func_node->get_predicate_tree_position(tid);
  49                 FuncInst * read_inst = func_node->get_inst(read);
  50                 Predicate * selected_branch = selectBranch(tid, curr_pred, read_inst);
  51
  52                 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
  53                 prune_writes(tid, selected_branch, rf_set, inst_act_map);
  54         }
  55
  56         // No write satisfies the selected predicate, so pause this thread.
  57         if ( rf_set->size() == 0 ) {
  58                 Thread * read_thread = execution->get_thread(tid);
  59                 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());
  60
  61                 // reset thread pending action and revert sequence numbers
  62                 read_thread->set_pending(read);
  63                 read->reset_seq_number();
  64                 execution->restore_last_seq_num();
  65
  66                 conditional_sleep(read_thread);
  67
  68                 find_threads(read);
  69
  70                 return -1;
  71 /*
  72                 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
  73                 for (uint i = 0; i < pruned_writes->size(); i++)
  74                         rf_set->push_back( (*pruned_writes)[i] );
  75                 pruned_writes->clear();
  76 */
  77         }
  78
  79         ASSERT(rf_set->size() != 0);
  80         int random_index = random() % rf_set->size();
  81
  82         return random_index;
  83 }
  84
  85 /* Select a random branch from the children of curr_pred
  86  * @return The selected branch
  87  */
  88 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
  89 {
  90         int thread_id = id_to_int(tid);
  91         if ( thrd_selected_child_branch.size() <= (uint) thread_id)
  92                 thrd_selected_child_branch.resize(thread_id + 1);
  93
  94         if (curr_pred == NULL || read_inst == NULL) {
  95                 thrd_selected_child_branch[thread_id] = NULL;
  96                 return NULL;
  97         }
  98
  99         ModelVector<Predicate *> * children = curr_pred->get_children();
 100         SnapVector<Predicate *> branches;
 101
 102         for (uint i = 0; i < children->size(); i++) {
 103                 Predicate * child = (*children)[i];
 104                 if (child->get_func_inst() == read_inst)
 105                         branches.push_back(child);
 106         }
 107
 108         // predicate children have not been generated
 109         if (branches.size() == 0) {
 110                 thrd_selected_child_branch[thread_id] = NULL;
 111                 return NULL;
 112         }
 113
 114         // randomly select a branch
 115         int random_index = random() % branches.size();
 116         Predicate * random_branch = branches[ random_index ];
 117         thrd_selected_child_branch[thread_id] = random_branch;
 118
 119         return random_branch;
 120 }
 121
 122 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
 123 {
 124         int thread_id = id_to_int(tid);
 125         if (thrd_selected_child_branch.size() <= (uint) thread_id)
 126                 return NULL;
 127
 128         return thrd_selected_child_branch[thread_id];
 129 }
 130
 131 /* Remove writes from the rf_set that do not satisfie the selected predicate,
 132  * and store them in thrd_pruned_writes
 133  *
 134  * @return true if rf_set is pruned
 135  */
 136 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
 137         SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
 138 {
 139         if (pred == NULL)
 140                 return false;
 141
 142         PredExprSet * pred_expressions = pred->get_pred_expressions();
 143         if (pred_expressions->getSize() == 0)   // unset predicates
 144                 return false;
 145
 146         int thread_id = id_to_int(tid);
 147         uint old_size = thrd_pruned_writes.size();
 148         if (thrd_pruned_writes.size() <= (uint) thread_id) {
 149                 uint new_size = thread_id + 1;
 150                 thrd_pruned_writes.resize(new_size);
 151                 for (uint i = old_size; i < new_size; i++)
 152                         thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
 153         }
 154         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
 155         pruned_writes->clear(); // clear the old pruned_writes set
 156
 157         bool pruned = false;
 158         uint index = 0;
 159
 160         ConcretePredicate * concrete_pred = pred->evaluate(inst_act_map, tid);
 161         SnapVector<struct concrete_pred_expr> * concrete_exprs = concrete_pred->getExpressions();
 162
 163         while ( index < rf_set->size() ) {
 164                 ModelAction * write_act = (*rf_set)[index];
 165                 uint64_t write_val = write_act->get_write_value();
 166                 bool satisfy_predicate = true;
 167
 168                 for (uint i = 0; i < concrete_exprs->size(); i++) {
 169                         struct concrete_pred_expr concrete = (*concrete_exprs)[i];
 170                         bool equality;
 171
 172                         switch (concrete.token) {
 173                                 case NOPREDICATE:
 174                                         return false;
 175                                 case EQUALITY:
 176                                         equality = (write_val == concrete.value);
 177                                         if (equality != concrete.equality)
 178                                                 satisfy_predicate = false;
 179                                         break;
 180                                 case NULLITY:
 181                                         equality = ((void*)write_val == NULL);
 182                                         if (equality != concrete.equality)
 183                                                 satisfy_predicate = false;
 184                                         break;
 185                                 default:
 186                                         model_print("unknown predicate token\n");
 187                                         break;
 188                         }
 189
 190                         if (!satisfy_predicate)
 191                                 break;
 192                 }
 193
 194                 if (!satisfy_predicate) {
 195                         ASSERT(rf_set != NULL);
 196                         (*rf_set)[index] = rf_set->back();
 197                         rf_set->pop_back();
 198                         pruned_writes->push_back(write_act);
 199                         pruned = true;
 200                 } else
 201                         index++;
 202         }
 203
 204         delete concrete_pred;
 205
 206         return pruned;
 207 }
 208
 209 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate.
 210  *
 211  * @param thread A thread whose last action is a read
 212  */
 213 void NewFuzzer::conditional_sleep(Thread * thread)
 214 {
 215         int index = paused_thread_set.size();
 216
 217         model->getScheduler()->add_sleep(thread);
 218         paused_thread_set.push_back(thread);
 219         paused_thread_table.put(thread, index); // Update table
 220
 221         /* Add the waiting condition to ModelHistory */
 222         ModelAction * read = thread->get_pending();
 223         thread_id_t tid = thread->get_id();
 224         FuncNode * func_node = history->get_curr_func_node(tid);
 225         inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
 226
 227         Predicate * selected_branch = get_selected_child_branch(tid);
 228         ConcretePredicate * concrete = selected_branch->evaluate(inst_act_map, tid);
 229         concrete->set_location(read->get_location());
 230
 231         history->add_waiting_write(concrete);
 232 }
 233
 234 bool NewFuzzer::has_paused_threads()
 235 {
 236         return paused_thread_set.size() != 0;
 237 }
 238
 239 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
 240 {
 241         if (numthreads == 0 && has_paused_threads()) {
 242                 wake_up_paused_threads(threadlist, &numthreads);
 243                 model_print("list size: %d, active t id: %d\n", numthreads, threadlist[0]);
 244         }
 245
 246         int random_index = random() % numthreads;
 247         int thread = threadlist[random_index];
 248         thread_id_t curr_tid = int_to_id(thread);
 249         return model->get_thread(curr_tid);
 250 }
 251
 252 /* Force waking up one of threads paused by Fuzzer, because otherwise
 253  * the Fuzzer is not making progress
 254  */
 255 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
 256 {
 257         int random_index = random() % paused_thread_set.size();
 258         Thread * thread = paused_thread_set[random_index];
 259         model->getScheduler()->remove_sleep(thread);
 260
 261         Thread * last_thread = paused_thread_set.back();
 262         paused_thread_set[random_index] = last_thread;
 263         paused_thread_set.pop_back();
 264         paused_thread_table.put(last_thread, random_index);     // Update table
 265         paused_thread_table.remove(thread);
 266
 267         thread_id_t tid = thread->get_id();
 268         history->remove_waiting_write(tid);
 269
 270         model_print("thread %d is woken up\n", tid);
 271         threadlist[*numthreads] = tid;
 272         (*numthreads)++;
 273 }
 274
 275 /* Wake up conditional sleeping threads if the desired write is available */
 276 void NewFuzzer::notify_paused_thread(Thread * thread)
 277 {
 278         ASSERT(paused_thread_table.contains(thread));
 279
 280         int index = paused_thread_table.get(thread);
 281         model->getScheduler()->remove_sleep(thread);
 282
 283         Thread * last_thread = paused_thread_set.back();
 284         paused_thread_set[index] = last_thread;
 285         paused_thread_set.pop_back();
 286         paused_thread_table.put(last_thread, index);    // Update table
 287         paused_thread_table.remove(thread);
 288
 289         thread_id_t tid = thread->get_id();
 290         history->remove_waiting_write(tid);
 291 }
 292
 293 /* Find threads that may write values that the pending read action is waiting for */
 294 void NewFuzzer::find_threads(ModelAction * pending_read)
 295 {
 296         void * location = pending_read->get_location();
 297         thread_id_t self_id = pending_read->get_tid();
 298         HashSet<thread_id_t, int, 0> waiting_for_threads(64);
 299
 300         SnapVector<FuncNode *> * func_node_list = history->getWrFuncNodes(location);
 301         for (uint i = 0; i < func_node_list->size(); i++) {
 302                 FuncNode * target_node = (*func_node_list)[i];
 303                 for (uint i = 1; i < execution->get_num_threads(); i++) {
 304                         thread_id_t tid = int_to_id(i);
 305                         if (tid == self_id)
 306                                 continue;
 307
 308                         FuncNode * node = history->get_curr_func_node(tid);
 309                         /* It is possible that thread tid is not in any FuncNode */
 310                         if (node == NULL)
 311                                 continue;
 312
 313                         int distance = node->compute_distance(target_node);
 314                         if (distance != -1) {
 315                                 waiting_for_threads.add(tid);
 316                                 model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
 317
 318                         }
 319
 320                 }
 321         }
 322
 323         /* Clear list first */
 324         WaitObj * wait_obj = history->getWaitObj(self_id);
 325         thrd_id_set_t * waiting_threads = wait_obj->getWaitingFor();
 326         waiting_threads->reset();
 327
 328         HSIterator<thread_id_t, int, 0> * it = waiting_for_threads.iterator();
 329         while (it->hasNext()) {
 330                 thread_id_t tid = it->next();
 331                 waiting_threads->add(tid);
 332         }
 333 }
 334
 335 bool NewFuzzer::shouldWait(const ModelAction * act)
 336 {
 337         return random() & 1;
 338 }