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