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                 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
  48                 Predicate * curr_pred = func_node->get_predicate_tree_position(tid);
  49                 FuncInst * read_inst = func_node->get_inst(read);
  50
  51                 Predicate * selected_branch = selectBranch(tid, curr_pred, read_inst);
  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 is unsuccessful\n", read->get_seq_number(), read_thread->get_id());
  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                 return -1;
  67 /*
  68                 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
  69                 for (uint i = 0; i < pruned_writes->size(); i++)
  70                         rf_set->push_back( (*pruned_writes)[i] );
  71                 pruned_writes->clear();
  72 */
  73         }
  74
  75         ASSERT(rf_set->size() != 0);
  76         int random_index = random() % rf_set->size();
  77
  78         return random_index;
  79 }
  80
  81 /* Select a random branch from the children of curr_pred
  82  * @return The selected branch
  83  */
  84 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
  85 {
  86         int thread_id = id_to_int(tid);
  87         if ( thrd_selected_child_branch.size() <= (uint) thread_id)
  88                 thrd_selected_child_branch.resize(thread_id + 1);
  89
  90         if (curr_pred == NULL || read_inst == NULL) {
  91                 thrd_selected_child_branch[thread_id] = NULL;
  92                 return NULL;
  93         }
  94
  95         ModelVector<Predicate *> * children = curr_pred->get_children();
  96         SnapVector<Predicate *> branches;
  97
  98         for (uint i = 0; i < children->size(); i++) {
  99                 Predicate * child = (*children)[i];
 100                 if (child->get_func_inst() == read_inst)
 101                         branches.push_back(child);
 102         }
 103
 104         // predicate children have not been generated
 105         if (branches.size() == 0) {
 106                 thrd_selected_child_branch[thread_id] = NULL;
 107                 return NULL;
 108         }
 109
 110         // randomly select a branch
 111         int random_index = random() % branches.size();
 112         Predicate * random_branch = branches[ random_index ];
 113         thrd_selected_child_branch[thread_id] = random_branch;
 114
 115         return random_branch;
 116 }
 117
 118 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
 119 {
 120         int thread_id = id_to_int(tid);
 121         if (thrd_selected_child_branch.size() <= (uint) thread_id)
 122                 return NULL;
 123
 124         return thrd_selected_child_branch[thread_id];
 125 }
 126
 127 /* Remove writes from the rf_set that do not satisfie the selected predicate,
 128  * and store them in thrd_pruned_writes
 129  *
 130  * @return true if rf_set is pruned
 131  */
 132 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
 133         SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
 134 {
 135         if (pred == NULL)
 136                 return false;
 137
 138         PredExprSet * pred_expressions = pred->get_pred_expressions();
 139         if (pred_expressions->getSize() == 0)   // unset predicates
 140                 return false;
 141
 142         int thread_id = id_to_int(tid);
 143         uint old_size = thrd_pruned_writes.size();
 144         if (thrd_pruned_writes.size() <= (uint) thread_id) {
 145                 uint new_size = thread_id + 1;
 146                 thrd_pruned_writes.resize(new_size);
 147                 for (uint i = old_size; i < new_size; i++)
 148                         thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
 149         }
 150         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
 151         pruned_writes->clear(); // clear the old pruned_writes set
 152
 153         bool pruned = false;
 154         uint index = 0;
 155
 156         ConcretePredicate * concrete_pred = pred->evaluate(inst_act_map, tid);
 157         SnapVector<struct concrete_pred_expr> * concrete_exprs = concrete_pred->getExpressions();
 158
 159         while ( index < rf_set->size() ) {
 160                 ModelAction * write_act = (*rf_set)[index];
 161                 uint64_t write_val = write_act->get_write_value();
 162                 bool satisfy_predicate = true;
 163
 164                 for (uint i = 0; i < concrete_exprs->size(); i++) {
 165                         struct concrete_pred_expr concrete = (*concrete_exprs)[i];
 166                         bool equality;
 167
 168                         switch (concrete.token) {
 169                                 case NOPREDICATE:
 170                                         return false;
 171                                 case EQUALITY:
 172                                         equality = (write_val == concrete.value);
 173                                         if (equality != concrete.equality)
 174                                                 satisfy_predicate = false;
 175                                         break;
 176                                 case NULLITY:
 177                                         equality = ((void*)write_val == NULL);
 178                                         if (equality != concrete.equality)
 179                                                 satisfy_predicate = false;
 180                                         break;
 181                                 default:
 182                                         model_print("unknown predicate token\n");
 183                                         break;
 184                         }
 185
 186                         if (!satisfy_predicate)
 187                                 break;
 188                 }
 189
 190                 if (!satisfy_predicate) {
 191                         ASSERT(rf_set != NULL);
 192                         (*rf_set)[index] = rf_set->back();
 193                         rf_set->pop_back();
 194                         pruned_writes->push_back(write_act);
 195                         pruned = true;
 196                 } else
 197                         index++;
 198         }
 199
 200         delete concrete_pred;
 201
 202         return pruned;
 203 }
 204
 205 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate.
 206  *
 207  * @param thread A thread whose last action is a read
 208  */
 209 void NewFuzzer::conditional_sleep(Thread * thread)
 210 {
 211         int index = paused_thread_set.size();
 212
 213         model->getScheduler()->add_sleep(thread);
 214         paused_thread_set.push_back(thread);
 215         paused_thread_table.put(thread, index); // Update table
 216
 217         /*  */
 218         ModelAction * read = thread->get_pending();
 219         thread_id_t tid = thread->get_id();
 220         FuncNode * func_node = history->get_curr_func_node(tid);
 221         inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
 222
 223         Predicate * selected_branch = get_selected_child_branch(tid);
 224         ConcretePredicate * concrete = selected_branch->evaluate(inst_act_map, tid);
 225         concrete->set_location(read->get_location());
 226
 227         history->add_waiting_write(concrete);
 228 }
 229
 230 bool NewFuzzer::has_paused_threads()
 231 {
 232         return paused_thread_set.size() != 0;
 233 }
 234
 235 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
 236 {
 237         if (numthreads == 0 && has_paused_threads()) {
 238                 wake_up_paused_threads(threadlist, &numthreads);
 239                 model_print("list size: %d\n", numthreads);
 240                 model_print("active t id: %d\n", threadlist[0]);
 241         }
 242
 243         int random_index = random() % numthreads;
 244         int thread = threadlist[random_index];
 245         thread_id_t curr_tid = int_to_id(thread);
 246         return model->get_thread(curr_tid);
 247 }
 248
 249 /* Force waking up one of threads paused by Fuzzer, because otherwise
 250  * the Fuzzer is not making progress
 251  */
 252 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
 253 {
 254         int random_index = random() % paused_thread_set.size();
 255         Thread * thread = paused_thread_set[random_index];
 256         model->getScheduler()->remove_sleep(thread);
 257
 258         Thread * last_thread = paused_thread_set.back();
 259         paused_thread_set[random_index] = last_thread;
 260         paused_thread_set.pop_back();
 261         paused_thread_table.put(last_thread, random_index);     // Update table
 262         paused_thread_table.remove(thread);
 263
 264         thread_id_t tid = thread->get_id();
 265         history->remove_waiting_write(tid);
 266
 267         model_print("thread %d is woken up\n", tid);
 268         threadlist[*numthreads] = tid;
 269         (*numthreads)++;
 270 }
 271
 272 /* Wake up conditional sleeping threads if the desired write is available */
 273 void NewFuzzer::notify_paused_thread(Thread * thread)
 274 {
 275         ASSERT(paused_thread_table.contains(thread));
 276
 277         int index = paused_thread_table.get(thread);
 278         model->getScheduler()->remove_sleep(thread);
 279
 280         Thread * last_thread = paused_thread_set.back();
 281         paused_thread_set[index] = last_thread;
 282         paused_thread_set.pop_back();
 283         paused_thread_table.put(last_thread, index);    // Update table
 284         paused_thread_table.remove(thread);
 285
 286         thread_id_t tid = thread->get_id();
 287         history->remove_waiting_write(tid);
 288 }
 289
 290 bool NewFuzzer::shouldWait(const ModelAction * act)
 291 {
 292         return random() & 1;
 293 }