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_last_func_inst(),
  18         thrd_selected_child_branch(),
  19         thrd_pruned_writes(),
  20         paused_thread_list(),
  21         paused_thread_table(128),
  22         failed_predicates(32)
  23 {}
  24
  25 /**
  26  * @brief Register the ModelHistory and ModelExecution engine
  27  */
  28 void NewFuzzer::register_engine(ModelHistory * history, ModelExecution *execution)
  29 {
  30         this->history = history;
  31         this->execution = execution;
  32 }
  33
  34 int NewFuzzer::selectWrite(ModelAction *read, SnapVector<ModelAction *> * rf_set)
  35 {
  36 //      return random() % rf_set->size();
  37
  38         thread_id_t tid = read->get_tid();
  39         int thread_id = id_to_int(tid);
  40
  41         if (thrd_last_read_act.size() <= (uint) thread_id) {
  42                 thrd_last_read_act.resize(thread_id + 1);
  43                 thrd_last_func_inst.resize(thread_id + 1);
  44         }
  45
  46         // A new read action is encountered, select a random child branch of current predicate
  47         if (read != thrd_last_read_act[thread_id]) {
  48                 FuncNode * func_node = history->get_curr_func_node(tid);
  49                 Predicate * curr_pred = func_node->get_predicate_tree_position(tid);
  50                 FuncInst * read_inst = func_node->get_inst(read);
  51                 Predicate * selected_branch = selectBranch(tid, curr_pred, read_inst);
  52
  53                 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
  54                 prune_writes(tid, selected_branch, rf_set, inst_act_map);
  55
  56                 if (!failed_predicates.isEmpty())
  57                         failed_predicates.reset();
  58
  59                 thrd_last_read_act[thread_id] = read;
  60                 thrd_last_func_inst[thread_id] = read_inst;
  61         }
  62
  63         // No write satisfies the selected predicate, so pause this thread.
  64         while ( rf_set->size() == 0 ) {
  65                 Thread * read_thread = execution->get_thread(tid);
  66                 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());
  67
  68                 if (find_threads(read)) {
  69                         // reset thread pending action and revert sequence numbers
  70                         read_thread->set_pending(read);
  71                         read->reset_seq_number();
  72                         execution->restore_last_seq_num();
  73
  74                         conditional_sleep(read_thread);
  75
  76                         // Returning -1 stops the while loop of ModelExecution::process_read
  77                         return -1;
  78                 } else {
  79                         Predicate * selected_branch = get_selected_child_branch(tid);
  80                         failed_predicates.put(selected_branch, true);
  81
  82                         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
  83                         for (uint i = 0; i < pruned_writes->size(); i++) {
  84                                 rf_set->push_back( (*pruned_writes)[i] );
  85                         }
  86
  87                         // Reselect a predicate and prune writes
  88                         Predicate * curr_pred = selected_branch->get_parent();
  89                         FuncInst * read_inst = thrd_last_func_inst[thread_id];
  90                         selected_branch = selectBranch(tid, curr_pred, read_inst);
  91
  92                         FuncNode * func_node = history->get_curr_func_node(tid);
  93                         inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
  94                         prune_writes(tid, selected_branch, rf_set, inst_act_map);
  95
  96                         ASSERT(selected_branch);
  97                 }
  98         }
  99
 100         ASSERT(rf_set->size() != 0);
 101         int random_index = random() % rf_set->size();
 102
 103         return random_index;
 104 }
 105
 106 /* Select a random branch from the children of curr_pred
 107  * @return The selected branch
 108  */
 109 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
 110 {
 111         int thread_id = id_to_int(tid);
 112         if ( thrd_selected_child_branch.size() <= (uint) thread_id)
 113                 thrd_selected_child_branch.resize(thread_id + 1);
 114
 115         if (curr_pred == NULL || read_inst == NULL) {
 116                 thrd_selected_child_branch[thread_id] = NULL;
 117                 return NULL;
 118         }
 119
 120         ModelVector<Predicate *> * children = curr_pred->get_children();
 121         SnapVector<Predicate *> branches;
 122
 123         for (uint i = 0; i < children->size(); i++) {
 124                 Predicate * child = (*children)[i];
 125                 if (child->get_func_inst() == read_inst && !failed_predicates.contains(child)) {
 126                         branches.push_back(child);
 127                 }
 128         }
 129
 130         // predicate children have not been generated
 131         if (branches.size() == 0) {
 132                 thrd_selected_child_branch[thread_id] = NULL;
 133                 return NULL;
 134         }
 135
 136         // randomly select a branch
 137         int random_index = random() % branches.size();
 138         Predicate * random_branch = branches[ random_index ];
 139         thrd_selected_child_branch[thread_id] = random_branch;
 140
 141         return random_branch;
 142 }
 143
 144 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
 145 {
 146         int thread_id = id_to_int(tid);
 147         if (thrd_selected_child_branch.size() <= (uint) thread_id)
 148                 return NULL;
 149
 150         return thrd_selected_child_branch[thread_id];
 151 }
 152
 153 /* Remove writes from the rf_set that do not satisfie the selected predicate,
 154  * and store them in thrd_pruned_writes
 155  *
 156  * @return true if rf_set is pruned
 157  */
 158 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
 159         SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
 160 {
 161         if (pred == NULL)
 162                 return false;
 163
 164         PredExprSet * pred_expressions = pred->get_pred_expressions();
 165         if (pred_expressions->getSize() == 0)   // unset predicates
 166                 return false;
 167
 168         int thread_id = id_to_int(tid);
 169         uint old_size = thrd_pruned_writes.size();
 170         if (thrd_pruned_writes.size() <= (uint) thread_id) {
 171                 uint new_size = thread_id + 1;
 172                 thrd_pruned_writes.resize(new_size);
 173                 for (uint i = old_size; i < new_size; i++)
 174                         thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
 175         }
 176         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
 177         pruned_writes->clear(); // clear the old pruned_writes set
 178
 179         bool pruned = false;
 180         uint index = 0;
 181
 182         ConcretePredicate * concrete_pred = pred->evaluate(inst_act_map, tid);
 183         SnapVector<struct concrete_pred_expr> * concrete_exprs = concrete_pred->getExpressions();
 184
 185         while ( index < rf_set->size() ) {
 186                 ModelAction * write_act = (*rf_set)[index];
 187                 uint64_t write_val = write_act->get_write_value();
 188                 bool satisfy_predicate = true;
 189
 190                 for (uint i = 0; i < concrete_exprs->size(); i++) {
 191                         struct concrete_pred_expr concrete = (*concrete_exprs)[i];
 192                         bool equality;
 193
 194                         switch (concrete.token) {
 195                                 case NOPREDICATE:
 196                                         return false;
 197                                 case EQUALITY:
 198                                         equality = (write_val == concrete.value);
 199                                         if (equality != concrete.equality)
 200                                                 satisfy_predicate = false;
 201                                         break;
 202                                 case NULLITY:
 203                                         equality = ((void*)write_val == NULL);
 204                                         if (equality != concrete.equality)
 205                                                 satisfy_predicate = false;
 206                                         break;
 207                                 default:
 208                                         model_print("unknown predicate token\n");
 209                                         break;
 210                         }
 211
 212                         if (!satisfy_predicate)
 213                                 break;
 214                 }
 215
 216                 if (!satisfy_predicate) {
 217                         ASSERT(rf_set != NULL);
 218                         (*rf_set)[index] = rf_set->back();
 219                         rf_set->pop_back();
 220                         pruned_writes->push_back(write_act);
 221                         pruned = true;
 222                 } else
 223                         index++;
 224         }
 225
 226         delete concrete_pred;
 227
 228         return pruned;
 229 }
 230
 231 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate.
 232  *
 233  * @param thread A thread whose last action is a read
 234  */
 235 void NewFuzzer::conditional_sleep(Thread * thread)
 236 {
 237         int index = paused_thread_list.size();
 238
 239         model->getScheduler()->add_sleep(thread);
 240         paused_thread_list.push_back(thread);
 241         paused_thread_table.put(thread, index); // Update table
 242
 243         /* Add the waiting condition to ModelHistory */
 244         ModelAction * read = thread->get_pending();
 245         thread_id_t tid = thread->get_id();
 246         FuncNode * func_node = history->get_curr_func_node(tid);
 247         inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
 248
 249         Predicate * selected_branch = get_selected_child_branch(tid);
 250         ConcretePredicate * concrete = selected_branch->evaluate(inst_act_map, tid);
 251         concrete->set_location(read->get_location());
 252
 253         history->add_waiting_write(concrete);
 254         /* history->add_waiting_thread is already called in find_threads */
 255 }
 256
 257 bool NewFuzzer::has_paused_threads()
 258 {
 259         return paused_thread_list.size() != 0;
 260 }
 261
 262 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
 263 {
 264         if (numthreads == 0 && has_paused_threads()) {
 265                 wake_up_paused_threads(threadlist, &numthreads);
 266                 //model_print("list size: %d, active t id: %d\n", numthreads, threadlist[0]);
 267         }
 268
 269         int random_index = random() % numthreads;
 270         int thread = threadlist[random_index];
 271         thread_id_t curr_tid = int_to_id(thread);
 272         return execution->get_thread(curr_tid);
 273 }
 274
 275 /* Force waking up one of threads paused by Fuzzer, because otherwise
 276  * the Fuzzer is not making progress
 277  */
 278 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
 279 {
 280         int random_index = random() % paused_thread_list.size();
 281         Thread * thread = paused_thread_list[random_index];
 282         model->getScheduler()->remove_sleep(thread);
 283
 284         Thread * last_thread = paused_thread_list.back();
 285         paused_thread_list[random_index] = last_thread;
 286         paused_thread_list.pop_back();
 287         paused_thread_table.put(last_thread, random_index);     // Update table
 288         paused_thread_table.remove(thread);
 289
 290         thread_id_t tid = thread->get_id();
 291         history->remove_waiting_write(tid);
 292         history->remove_waiting_thread(tid);
 293
 294         model_print("thread %d is woken up\n", tid);
 295         threadlist[*numthreads] = tid;
 296         (*numthreads)++;
 297 }
 298
 299 /* Wake up conditional sleeping threads if the desired write is available */
 300 void NewFuzzer::notify_paused_thread(Thread * thread)
 301 {
 302         ASSERT(paused_thread_table.contains(thread));
 303
 304         int index = paused_thread_table.get(thread);
 305         model->getScheduler()->remove_sleep(thread);
 306
 307         Thread * last_thread = paused_thread_list.back();
 308         paused_thread_list[index] = last_thread;
 309         paused_thread_list.pop_back();
 310         paused_thread_table.put(last_thread, index);    // Update table
 311         paused_thread_table.remove(thread);
 312
 313         thread_id_t tid = thread->get_id();
 314         history->remove_waiting_write(tid);
 315         history->remove_waiting_thread(tid);
 316 }
 317
 318 /* Find threads that may write values that the pending read action is waiting for
 319  * @return True if any thread is found
 320  */
 321 bool NewFuzzer::find_threads(ModelAction * pending_read)
 322 {
 323         ASSERT(pending_read->is_read());
 324
 325         void * location = pending_read->get_location();
 326         thread_id_t self_id = pending_read->get_tid();
 327         bool finds_waiting_for = false;
 328
 329         SnapVector<FuncNode *> * func_node_list = history->getWrFuncNodes(location);
 330         for (uint i = 0; i < func_node_list->size(); i++) {
 331                 FuncNode * target_node = (*func_node_list)[i];
 332                 for (uint i = 1; i < execution->get_num_threads(); i++) {
 333                         thread_id_t tid = int_to_id(i);
 334                         if (tid == self_id)
 335                                 continue;
 336
 337                         FuncNode * node = history->get_curr_func_node(tid);
 338                         /* It is possible that thread tid is not in any FuncNode */
 339                         if (node == NULL)
 340                                 continue;
 341
 342                         int distance = node->compute_distance(target_node);
 343                         if (distance != -1) {
 344                                 history->add_waiting_thread(self_id, tid, target_node, distance);
 345                                 finds_waiting_for = true;
 346                                 model_print("thread: %d; distance from node %d to node %d: %d\n", tid, node->get_func_id(), target_node->get_func_id(), distance);
 347                         }
 348                 }
 349         }
 350
 351         return finds_waiting_for;
 352 }
 353
 354 bool NewFuzzer::shouldWait(const ModelAction * act)
 355 {
 356         return random() & 1;
 357 }