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