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                 read_thread->set_pending(read);
  56                 read->reset_seq_number();       // revert some operations
  57                 execution->restore_last_seq_num();
  58
  59                 conditional_sleep(read_thread);
  60                 return -1;
  61 /*
  62                 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
  63                 for (uint i = 0; i < pruned_writes->size(); i++)
  64                         rf_set->push_back( (*pruned_writes)[i] );
  65                 pruned_writes->clear();
  66 */
  67         }
  68
  69         ASSERT(rf_set->size() != 0);
  70         int random_index = random() % rf_set->size();
  71
  72         return random_index;
  73 }
  74
  75 /* Select a random branch from the children of curr_pred
  76  * @return The selected branch
  77  */
  78 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
  79 {
  80         int thread_id = id_to_int(tid);
  81         if ( thrd_selected_child_branch.size() <= (uint) thread_id)
  82                 thrd_selected_child_branch.resize(thread_id + 1);
  83
  84         if (curr_pred == NULL || read_inst == NULL) {
  85                 thrd_selected_child_branch[thread_id] = NULL;
  86                 return NULL;
  87         }
  88
  89         ModelVector<Predicate *> * children = curr_pred->get_children();
  90         SnapVector<Predicate *> branches;
  91
  92         for (uint i = 0; i < children->size(); i++) {
  93                 Predicate * child = (*children)[i];
  94                 if (child->get_func_inst() == read_inst)
  95                         branches.push_back(child);
  96         }
  97
  98         // predicate children have not been generated
  99         if (branches.size() == 0) {
 100                 thrd_selected_child_branch[thread_id] = NULL;
 101                 return NULL;
 102         }
 103
 104         // randomly select a branch
 105         int random_index = random() % branches.size();
 106         Predicate * random_branch = branches[ random_index ];
 107         thrd_selected_child_branch[thread_id] = random_branch;
 108
 109         return random_branch;
 110 }
 111
 112 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
 113 {
 114         int thread_id = id_to_int(tid);
 115         if (thrd_selected_child_branch.size() <= (uint) thread_id)
 116                 return NULL;
 117
 118         return thrd_selected_child_branch[thread_id];
 119 }
 120
 121 /* Remove writes from the rf_set that do not satisfie the selected predicate,
 122  * and store them in thrd_pruned_writes
 123  *
 124  * @return true if rf_set is pruned
 125  */
 126 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
 127         SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
 128 {
 129         if (pred == NULL)
 130                 return false;
 131
 132         PredExprSet * pred_expressions = pred->get_pred_expressions();
 133         if (pred_expressions->getSize() == 0)   // unset predicates
 134                 return false;
 135
 136         int thread_id = id_to_int(tid);
 137         uint old_size = thrd_pruned_writes.size();
 138         if (thrd_pruned_writes.size() <= (uint) thread_id) {
 139                 uint new_size = thread_id + 1;
 140                 thrd_pruned_writes.resize(new_size);
 141                 for (uint i = old_size; i < new_size; i++)
 142                         thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
 143         }
 144         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
 145         pruned_writes->clear(); // clear the old pruned_writes set
 146
 147         bool pruned = false;
 148         uint index = 0;
 149         while ( index < rf_set->size() ) {
 150                 ModelAction * write_act = (*rf_set)[index];
 151                 bool satisfy_predicate = true;
 152
 153                 PredExprSetIter * pred_expr_it = pred_expressions->iterator();
 154                 while (pred_expr_it->hasNext()) {
 155                         struct pred_expr * expression = pred_expr_it->next();
 156                         uint64_t write_val = write_act->get_write_value();
 157                         bool equality;
 158
 159                         // No predicate, return false
 160                         if (expression->token == NOPREDICATE)
 161                                 return pruned;
 162
 163                         switch(expression->token) {
 164                                 case EQUALITY:
 165                                         FuncInst * to_be_compared;
 166                                         ModelAction * last_act;
 167                                         uint64_t last_read;
 168
 169                                         to_be_compared = expression->func_inst;
 170                                         last_act = inst_act_map->get(to_be_compared);
 171                                         last_read = last_act->get_reads_from_value();
 172
 173                                         equality = (write_val == last_read);
 174                                         if (equality != expression->value)
 175                                                 satisfy_predicate = false;
 176                                         break;
 177                                 case NULLITY:
 178                                         equality = ((void*)write_val == NULL);
 179                                         if (equality != expression->value)
 180                                                 satisfy_predicate = false;
 181                                         break;
 182                                 default:
 183                                         model_print("unknown predicate token\n");
 184                                         break;
 185                         }
 186
 187                         if (!satisfy_predicate)
 188                                 break;
 189                 }
 190
 191                 if (!satisfy_predicate) {
 192                         ASSERT(rf_set != NULL);
 193                         (*rf_set)[index] = rf_set->back();
 194                         rf_set->pop_back();
 195                         pruned_writes->push_back(write_act);
 196                         pruned = true;
 197                 } else
 198                         index++;
 199         }
 200
 201         return pruned;
 202 }
 203
 204 /* @brief Put a thread to sleep because no writes in rf_set satisfies the selected predicate.
 205  *
 206  * @param thread A thread whose last action is a read
 207  */
 208 void NewFuzzer::conditional_sleep(Thread * thread)
 209 {
 210         model->getScheduler()->add_sleep(thread);
 211         paused_thread_set.push_back(thread);
 212 }
 213
 214 bool NewFuzzer::has_paused_threads()
 215 {
 216         return paused_thread_set.size() != 0;
 217 }
 218
 219 Thread * NewFuzzer::selectThread(int * threadlist, int numthreads)
 220 {
 221         if (numthreads == 0 && has_paused_threads()) {
 222                 wake_up_paused_threads(threadlist, &numthreads);
 223                 model_print("list size: %d\n", numthreads);
 224                 model_print("active t id: %d\n", threadlist[0]);
 225         }
 226
 227         int random_index = random() % numthreads;
 228         int thread = threadlist[random_index];
 229         thread_id_t curr_tid = int_to_id(thread);
 230         return model->get_thread(curr_tid);
 231 }
 232
 233 void NewFuzzer::wake_up_paused_threads(int * threadlist, int * numthreads)
 234 {
 235         int random_index = random() % paused_thread_set.size();
 236         Thread * thread = paused_thread_set[random_index];
 237         model->getScheduler()->remove_sleep(thread);
 238
 239         paused_thread_set[random_index] = paused_thread_set.back();
 240         paused_thread_set.pop_back();
 241
 242         model_print("thread %d is woken up\n", thread->get_id());
 243         threadlist[*numthreads] = thread->get_id();
 244         (*numthreads)++;
 245 }