newfuzzer.cc

   1 #include "newfuzzer.h"
   2 #include "threads-model.h"
   3 #include "model.h"
   4 #include "action.h"
   5 #include "execution.h"
   6 #include "funcnode.h"
   7 #include "schedule.h"
   8
   9 NewFuzzer::NewFuzzer() :
  10         thrd_last_read_act(),
  11         thrd_curr_pred(),
  12         thrd_selected_child_branch(),
  13         thrd_pruned_writes(),
  14         paused_thread_set()
  15 {}
  16
  17 /**
  18  * @brief Register the ModelHistory and ModelExecution engine
  19  */
  20 void NewFuzzer::register_engine(ModelHistory * history, ModelExecution *execution)
  21 {
  22         this->history = history;
  23         this->execution = execution;
  24 }
  25
  26 int NewFuzzer::selectWrite(ModelAction *read, SnapVector<ModelAction *> * rf_set)
  27 {
  28         thread_id_t tid = read->get_tid();
  29         int thread_id = id_to_int(tid);
  30
  31         if (thrd_last_read_act.size() <= (uint) thread_id)
  32                 thrd_last_read_act.resize(thread_id + 1);
  33
  34         // A new read action is encountered, select a random child branch of current predicate
  35         if (read != thrd_last_read_act[thread_id]) {
  36                 thrd_last_read_act[thread_id] = read;
  37
  38                 SnapVector<func_id_list_t> * thrd_func_list = execution->get_thrd_func_list();
  39                 uint32_t func_id = (*thrd_func_list)[thread_id].back();
  40                 FuncNode * func_node = history->get_func_node(func_id);
  41                 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
  42                 Predicate * curr_pred = func_node->get_predicate_tree_position(tid);
  43                 FuncInst * read_inst = func_node->get_inst(read);
  44
  45                 Predicate * selected_branch = selectBranch(tid, curr_pred, read_inst);
  46                 prune_writes(tid, selected_branch, rf_set, inst_act_map);
  47         }
  48
  49         // TODO: make this thread sleep if no write satisfies the chosen predicate
  50         // if no read satisfies the selected predicate
  51         if ( rf_set->size() == 0 ) {
  52                 Thread * read_thread = execution->get_thread(tid);
  53                 model_print("the %d read action of thread %d is unsuccessful\n", read->get_seq_number(), read_thread->get_id());
  54
  55                 // reset thread pending action and revert sequence numbers
  56                 read_thread->set_pending(read);
  57                 read->reset_seq_number();
  58                 execution->restore_last_seq_num();
  59
  60                 conditional_sleep(read_thread);
  61                 return -1;
  62 /*
  63                 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
  64                 for (uint i = 0; i < pruned_writes->size(); i++)
  65                         rf_set->push_back( (*pruned_writes)[i] );
  66                 pruned_writes->clear();
  67 */
  68         }
  69
  70         ASSERT(rf_set->size() != 0);
  71         int random_index = random() % rf_set->size();
  72
  73         return random_index;
  74 }
  75
  76 /* Select a random branch from the children of curr_pred
  77  * @return The selected branch
  78  */
  79 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
  80 {
  81         int thread_id = id_to_int(tid);
  82         if ( thrd_selected_child_branch.size() <= (uint) thread_id)
  83                 thrd_selected_child_branch.resize(thread_id + 1);
  84
  85         if (curr_pred == NULL || read_inst == NULL) {
  86                 thrd_selected_child_branch[thread_id] = NULL;
  87                 return NULL;
  88         }
  89
  90         ModelVector<Predicate *> * children = curr_pred->get_children();
  91         SnapVector<Predicate *> branches;
  92
  93         for (uint i = 0; i < children->size(); i++) {
  94                 Predicate * child = (*children)[i];
  95                 if (child->get_func_inst() == read_inst)
  96                         branches.push_back(child);
  97         }
  98
  99         // predicate children have not been generated
 100         if (branches.size() == 0) {
 101                 thrd_selected_child_branch[thread_id] = NULL;
 102                 return NULL;
 103         }
 104
 105         // randomly select a branch
 106         int random_index = random() % branches.size();
 107         Predicate * random_branch = branches[ random_index ];
 108         thrd_selected_child_branch[thread_id] = random_branch;
 109
 110         return random_branch;
 111 }
 112
 113 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
 114 {
 115         int thread_id = id_to_int(tid);
 116         if (thrd_selected_child_branch.size() <= (uint) thread_id)
 117                 return NULL;
 118
 119         return thrd_selected_child_branch[thread_id];
 120 }
 121
 122 /* Remove writes from the rf_set that do not satisfie the selected predicate,
 123  * and store them in thrd_pruned_writes
 124  *
 125  * @return true if rf_set is pruned
 126  */
 127 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
 128         SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
 129 {
 130         if (pred == NULL)
 131                 return false;
 132
 133         PredExprSet * pred_expressions = pred->get_pred_expressions();
 134         if (pred_expressions->getSize() == 0)   // unset predicates
 135                 return false;
 136
 137         int thread_id = id_to_int(tid);
 138         uint old_size = thrd_pruned_writes.size();
 139         if (thrd_pruned_writes.size() <= (uint) thread_id) {
 140                 uint new_size = thread_id + 1;
 141                 thrd_pruned_writes.resize(new_size);
 142                 for (uint i = old_size; i < new_size; i++)
 143                         thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
 144         }
 145         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
 146         pruned_writes->clear(); // clear the old pruned_writes set
 147
 148         bool pruned = false;
 149         uint index = 0;
 150         while ( index < rf_set->size() ) {
 151                 ModelAction * write_act = (*rf_set)[index];
 152                 bool satisfy_predicate = true;
 153
 154                 PredExprSetIter * pred_expr_it = pred_expressions->iterator();
 155                 while (pred_expr_it->hasNext()) {
 156                         struct pred_expr * expression = pred_expr_it->next();
 157                         uint64_t write_val = write_act->get_write_value();
 158                         bool equality;
 159
 160                         // No predicate, return false
 161                         if (expression->token == NOPREDICATE)
 162                                 return pruned;
 163
 164                         switch(expression->token) {
 165                                 case EQUALITY:
 166                                         FuncInst * to_be_compared;
 167                                         ModelAction * last_act;
 168                                         uint64_t last_read;
 169
 170                                         to_be_compared = expression->func_inst;
 171                                         last_act = inst_act_map->get(to_be_compared);
 172                                         last_read = last_act->get_reads_from_value();
 173
 174                                         equality = (write_val == last_read);
 175                                         if (equality != expression->value)
 176                                                 satisfy_predicate = false;
 177                                         break;
 178                                 case NULLITY:
 179                                         equality = ((void*)write_val == NULL);
 180                                         if (equality != expression->value)
 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         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         model->getScheduler()->add_sleep(thread);
 212         paused_thread_set.push_back(thread);
 213 }
 214
 215 bool NewFuzzer::has_paused_threads()
 216 {
 217         return paused_thread_set.size() != 0;
 218 }
 219
 220 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
 221 {
 222         if (numthreads == 0 && has_paused_threads()) {
 223                 wake_up_paused_threads(threadlist, &numthreads);
 224                 model_print("list size: %d\n", numthreads);
 225                 model_print("active t id: %d\n", threadlist[0]);
 226         }
 227
 228         int random_index = random() % numthreads;
 229         int thread = threadlist[random_index];
 230         thread_id_t curr_tid = int_to_id(thread);
 231         return model->get_thread(curr_tid);
 232 }
 233
 234 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
 235 {
 236         int random_index = random() % paused_thread_set.size();
 237         Thread * thread = paused_thread_set[random_index];
 238         model->getScheduler()->remove_sleep(thread);
 239
 240         paused_thread_set[random_index] = paused_thread_set.back();
 241         paused_thread_set.pop_back();
 242
 243         model_print("thread %d is woken up\n", thread->get_id());
 244         threadlist[*numthreads] = thread->get_id();
 245         (*numthreads)++;
 246 }
 247
 248 bool NewFuzzer::shouldWait(const ModelAction * act)
 249 {
 250         return random() & 1;
 251 }