check_atomic_inc_dec.c

   1 /*
   2  * Copyright (C) 2016 Oracle.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
  16  */
  17
  18 #include <ctype.h>
  19
  20 #include "smatch.h"
  21 #include "smatch_extra.h"
  22 #include "smatch_slist.h"
  23
  24 static int my_id;
  25
  26 STATE(inc);
  27 STATE(start_state);
  28 STATE(dec);
  29
  30 struct ref_func_info {
  31         const char *name;
  32         int type;
  33         int param;
  34         const char *key;
  35         func_hook *call_back;
  36         bool implied;
  37         long long implies_start, implies_end;
  38 };
  39
  40 static void match_atomic_add(const char *fn, struct expression *expr, void *_unused);
  41
  42 static struct ref_func_info func_table[] = {
  43         { "atomic_inc", ATOMIC_INC, 0, "$->counter" },
  44         { "atomic_long_inc", ATOMIC_INC, 0, "$->counter" },
  45         { "atomic_inc_return", ATOMIC_INC, 0, "$->counter" },
  46
  47         { "atomic_add_return", ATOMIC_INC, 1, "$->counter", match_atomic_add },
  48
  49         { "atomic_dec", ATOMIC_DEC, 0, "$->counter" },
  50         { "atomic_dec_return", ATOMIC_DEC, 0, "$->counter" },
  51         { "atomic_dec_and_test", ATOMIC_DEC, 0, "$->counter" },
  52         { "atomic_long_dec", ATOMIC_DEC, 0, "$->counter" },
  53         { "atomic_long_dec_and_test", ATOMIC_DEC, 0, "$->counter" },
  54         { "atomic64_dec_and_test", ATOMIC_DEC, 0, "$->counter" },
  55         { "_atomic_dec_and_lock", ATOMIC_DEC, 0, "$->counter" },
  56
  57         { "atomic_sub", ATOMIC_DEC, 1, "$->counter" },
  58         { "atomic_sub_return", ATOMIC_DEC, 1, "$->counter" },
  59         { "atomic_sub_and_test", ATOMIC_DEC, 1, "$->counter" },
  60         { "atomic_long_sub_and_test", ATOMIC_DEC, 1, "$->counter" },
  61         { "atomic64_sub_and_test", ATOMIC_DEC, 1, "$->counter" },
  62
  63         { "refcount_inc", ATOMIC_INC, 0, "$->ref.counter" },
  64         { "refcount_dec", ATOMIC_DEC, 0, "$->ref.counter" },
  65         { "refcount_dec_and_test", ATOMIC_DEC, 0, "$->ref.counter" },
  66         { "refcount_add", ATOMIC_INC, 1, "$->ref.counter" },
  67         { "refcount_sub_and_test", ATOMIC_DEC, 1, "$->ref.counter" },
  68
  69         { "pm_runtime_get_sync", ATOMIC_INC, 0, "$->power.usage_count.counter" },
  70         { "of_clk_del_provider", ATOMIC_DEC, 0, "$->kobj.kref.refcount.ref.counter" },
  71
  72         { "refcount_inc_not_zero", ATOMIC_INC, 0, "$->ref.counter", NULL, true, 1, 1},
  73         { "refcount_add_not_zero", ATOMIC_INC, 1, "$->ref.counter", NULL, true, 1, 1},
  74
  75         { "atomic_dec_if_positive", ATOMIC_DEC, 0, "$->counter", NULL, true, 0, INT_MAX},
  76
  77         { "of_node_get", ATOMIC_INC, 0, "$->kobj.kref.refcount.ref.counter" },
  78         { "of_node_put", ATOMIC_DEC, 0, "$->kobj.kref.refcount.ref.counter" },
  79         { "of_get_parent", ATOMIC_INC, -1, "$->kobj.kref.refcount.ref.counter" },
  80         { "of_clk_del_provider", ATOMIC_DEC, 0, "$->kobj.kref.refcount.ref.counter" },
  81 };
  82
  83 static struct smatch_state *unmatched_state(struct sm_state *sm)
  84 {
  85         /*
  86          * We default to decremented.  For example, say we have:
  87          *      if (p)
  88          *              atomic_dec(p);
  89          *      <- p is decreemented.
  90          *
  91          */
  92         if ((sm->state == &dec) &&
  93             parent_is_gone_var_sym(sm->name, sm->sym))
  94                 return sm->state;
  95         return &start_state;
  96 }
  97
  98 static struct stree *start_states;
  99 static struct stree_stack *saved_stack;
 100 static void set_start_state(const char *name, struct symbol *sym, struct smatch_state *start)
 101 {
 102         struct smatch_state *orig;
 103
 104         orig = get_state_stree(start_states, my_id, name, sym);
 105         if (!orig)
 106                 set_state_stree(&start_states, my_id, name, sym, start);
 107         else if (orig != start)
 108                 set_state_stree(&start_states, my_id, name, sym, &undefined);
 109 }
 110
 111 static struct sm_state *get_best_match(const char *key)
 112 {
 113         struct sm_state *sm;
 114         struct sm_state *match;
 115         int cnt = 0;
 116         int start_pos, state_len, key_len, chunks, i;
 117
 118         if (strncmp(key, "$->", 3) == 0)
 119                 key += 3;
 120
 121         key_len = strlen(key);
 122         chunks = 0;
 123         for (i = key_len - 1; i > 0; i--) {
 124                 if (key[i] == '>' || key[i] == '.')
 125                         chunks++;
 126                 if (chunks == 2) {
 127                         key += (i + 1);
 128                         key_len = strlen(key);
 129                         break;
 130                 }
 131         }
 132
 133         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 134                 state_len = strlen(sm->name);
 135                 if (state_len < key_len)
 136                         continue;
 137                 start_pos = state_len - key_len;
 138                 if ((start_pos == 0 || !isalnum(sm->name[start_pos - 1])) &&
 139                     strcmp(sm->name + start_pos, key) == 0) {
 140                         cnt++;
 141                         match = sm;
 142                 }
 143         } END_FOR_EACH_SM(sm);
 144
 145         if (cnt == 1)
 146                 return match;
 147         return NULL;
 148 }
 149
 150 static void db_inc_dec(struct expression *expr, int param, const char *key, int inc_dec)
 151 {
 152         struct sm_state *start_sm;
 153         struct expression *arg;
 154         char *name;
 155         struct symbol *sym;
 156         bool free_at_end = true;
 157
 158         while (expr->type == EXPR_ASSIGNMENT)
 159                 expr = strip_expr(expr->right);
 160         if (expr->type != EXPR_CALL)
 161                 return;
 162
 163         arg = get_argument_from_call_expr(expr->args, param);
 164         if (!arg)
 165                 return;
 166
 167         name = get_variable_from_key(arg, key, &sym);
 168         if (!name || !sym)
 169                 goto free;
 170
 171         start_sm = get_sm_state(my_id, name, sym);
 172         if (!start_sm && inc_dec == ATOMIC_DEC) {
 173                 start_sm = get_best_match(key);
 174                 if (start_sm) {
 175                         free_string(name);
 176                         free_at_end = false;
 177                         name = (char *)start_sm->name;
 178                         sym = start_sm->sym;
 179                 }
 180         }
 181
 182         if (inc_dec == ATOMIC_INC) {
 183                 if (!start_sm)
 184                         set_start_state(name, sym, &dec);
 185 //              set_refcount_inc(name, sym);
 186                 set_state(my_id, name, sym, &inc);
 187         } else {
 188 //              set_refcount_dec(name, sym);
 189                 if (!start_sm)
 190                         set_start_state(name, sym, &inc);
 191
 192                 if (start_sm && start_sm->state == &inc)
 193                         set_state(my_id, name, sym, &start_state);
 194                 else
 195                         set_state(my_id, name, sym, &dec);
 196         }
 197
 198 free:
 199         if (free_at_end)
 200                 free_string(name);
 201 }
 202
 203 static bool is_inc_dec_primitive(struct expression *expr)
 204 {
 205         int i;
 206
 207         while (expr->type == EXPR_ASSIGNMENT)
 208                 expr = strip_expr(expr->right);
 209         if (expr->type != EXPR_CALL)
 210                 return false;
 211
 212         if (expr->fn->type != EXPR_SYMBOL)
 213                 return false;
 214
 215         for (i = 0; i < ARRAY_SIZE(func_table); i++) {
 216                 if (sym_name_is(func_table[i].name, expr->fn))
 217                         return true;
 218         }
 219
 220         return false;
 221 }
 222
 223 static void db_inc(struct expression *expr, int param, char *key, char *value)
 224 {
 225         if (is_inc_dec_primitive(expr))
 226                 return;
 227         db_inc_dec(expr, param, key, ATOMIC_INC);
 228 }
 229
 230 static void db_dec(struct expression *expr, int param, char *key, char *value)
 231 {
 232         if (is_inc_dec_primitive(expr))
 233                 return;
 234         db_inc_dec(expr, param, key, ATOMIC_DEC);
 235 }
 236
 237 static void match_atomic_add(const char *fn, struct expression *expr, void *_unused)
 238 {
 239         struct expression *amount;
 240         sval_t sval;
 241
 242         amount = get_argument_from_call_expr(expr->args, 0);
 243         if (get_implied_value(amount, &sval) && sval_is_negative(sval)) {
 244                 db_inc_dec(expr, 1, "$->counter", ATOMIC_DEC);
 245                 return;
 246         }
 247
 248         db_inc_dec(expr, 1, "$->counter", ATOMIC_INC);
 249 }
 250
 251 static void refcount_function(const char *fn, struct expression *expr, void *data)
 252 {
 253         struct ref_func_info *info = data;
 254
 255         db_inc_dec(expr, info->param, info->key, info->type);
 256 }
 257
 258 static void refcount_implied(const char *fn, struct expression *call_expr,
 259                              struct expression *assign_expr, void *data)
 260 {
 261         struct ref_func_info *info = data;
 262
 263
 264         db_inc_dec(call_expr, info->param, info->key, info->type);
 265 }
 266
 267 static bool is_maybe_dec(struct sm_state *sm)
 268 {
 269         if (sm->state == &dec)
 270                 return true;
 271         if (slist_has_state(sm->possible, &dec) &&
 272             !slist_has_state(sm->possible, &inc))
 273                 return true;
 274         return false;
 275 }
 276
 277 static void match_return_info(int return_id, char *return_ranges, struct expression *expr)
 278 {
 279         struct sm_state *sm;
 280         const char *param_name;
 281         int param;
 282
 283         if (is_impossible_path())
 284                 return;
 285
 286         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 287                 if (sm->state != &inc && !is_maybe_dec(sm))
 288                         continue;
 289                 if (sm->state == get_state_stree(start_states, my_id, sm->name, sm->sym))
 290                         continue;
 291                 if (parent_is_gone_var_sym(sm->name, sm->sym))
 292                         continue;
 293                 param = get_param_num_from_sym(sm->sym);
 294                 if (param < 0)
 295                         continue;
 296                 param_name = get_param_name(sm);
 297                 if (!param_name)
 298                         continue;
 299                 sql_insert_return_states(return_id, return_ranges,
 300                                          (sm->state == &inc) ? ATOMIC_INC : ATOMIC_DEC,
 301                                          param, param_name, "");
 302         } END_FOR_EACH_SM(sm);
 303 }
 304
 305 enum {
 306         EMPTY, NEGATIVE, ZERO, POSITIVE, NUM_BUCKETS
 307 };
 308
 309 static int success_fail_positive(struct range_list *rl)
 310 {
 311         if (!rl)
 312                 return EMPTY;
 313
 314         if (!is_whole_rl(rl) && sval_is_negative(rl_min(rl)))
 315                 return NEGATIVE;
 316
 317         if (rl_min(rl).value == 0)
 318                 return ZERO;
 319
 320         return POSITIVE;
 321 }
 322
 323 static void check_counter(const char *name, struct symbol *sym)
 324 {
 325         struct range_list *inc_lines = NULL;
 326         struct range_list *dec_lines = NULL;
 327         int inc_buckets[NUM_BUCKETS] = {};
 328         int dec_buckets[NUM_BUCKETS] = {};
 329         struct stree *stree, *orig_stree;
 330         struct smatch_state *state;
 331         struct sm_state *return_sm;
 332         struct sm_state *sm;
 333         sval_t line = sval_type_val(&int_ctype, 0);
 334         int bucket;
 335
 336         /* static variable are probably just counters */
 337         if (sym->ctype.modifiers & MOD_STATIC &&
 338             !(sym->ctype.modifiers & MOD_TOPLEVEL))
 339                 return;
 340
 341         FOR_EACH_PTR(get_all_return_strees(), stree) {
 342                 orig_stree = __swap_cur_stree(stree);
 343
 344                 if (is_impossible_path())
 345                         goto swap_stree;
 346
 347                 return_sm = get_sm_state(RETURN_ID, "return_ranges", NULL);
 348                 if (!return_sm)
 349                         goto swap_stree;
 350                 line.value = return_sm->line;
 351
 352                 if (get_state_stree(start_states, my_id, name, sym) == &inc)
 353                         goto swap_stree;
 354
 355                 if (parent_is_gone_var_sym(name, sym))
 356                         goto swap_stree;
 357
 358                 sm = get_sm_state(my_id, name, sym);
 359                 if (sm)
 360                         state = sm->state;
 361                 else
 362                         state = &start_state;
 363
 364                 if (state != &inc &&
 365                     state != &dec &&
 366                     state != &start_state)
 367                         goto swap_stree;
 368
 369                 bucket = success_fail_positive(estate_rl(return_sm->state));
 370
 371                 if (state == &inc) {
 372                         add_range(&inc_lines, line, line);
 373                         inc_buckets[bucket] = true;
 374                 }
 375                 if (state == &dec || state == &start_state) {
 376                         add_range(&dec_lines, line, line);
 377                         dec_buckets[bucket] = true;
 378                 }
 379 swap_stree:
 380                 __swap_cur_stree(orig_stree);
 381         } END_FOR_EACH_PTR(stree);
 382
 383         if (inc_buckets[NEGATIVE] &&
 384             inc_buckets[ZERO]) {
 385                 // sm_warning("XXX '%s' not decremented on lines: %s.", name, show_rl(inc_lines));
 386         }
 387
 388 }
 389
 390 static void match_check_missed(struct symbol *sym)
 391 {
 392         struct sm_state *sm;
 393
 394         FOR_EACH_MY_SM(my_id, get_all_return_states(), sm) {
 395                 check_counter(sm->name, sm->sym);
 396         } END_FOR_EACH_SM(sm);
 397 }
 398
 399 int on_atomic_dec_path(void)
 400 {
 401         struct sm_state *sm;
 402
 403         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
 404                 if (sm->state == &dec)
 405                         return 1;
 406         } END_FOR_EACH_SM(sm);
 407
 408         return 0;
 409 }
 410
 411 int was_inced(const char *name, struct symbol *sym)
 412 {
 413         return get_state(my_id, name, sym) == &inc;
 414 }
 415
 416 static void match_save_states(struct expression *expr)
 417 {
 418         push_stree(&saved_stack, start_states);
 419         start_states = NULL;
 420 }
 421
 422 static void match_restore_states(struct expression *expr)
 423 {
 424         start_states = pop_stree(&saved_stack);
 425 }
 426
 427 static void match_after_func(struct symbol *sym)
 428 {
 429         free_stree(&start_states);
 430 }
 431
 432 void check_atomic_inc_dec(int id)
 433 {
 434         struct ref_func_info *info;
 435         int i;
 436
 437         my_id = id;
 438
 439         if (option_project != PROJ_KERNEL)
 440                 return;
 441
 442         add_unmatched_state_hook(my_id, &unmatched_state);
 443
 444         add_split_return_callback(match_return_info);
 445         select_return_states_hook(ATOMIC_INC, &db_inc);
 446         select_return_states_hook(ATOMIC_DEC, &db_dec);
 447
 448         for (i = 0; i < ARRAY_SIZE(func_table); i++) {
 449                 info = &func_table[i];
 450
 451                 if (info->call_back) {
 452                         add_function_hook(info->name, info->call_back, info);
 453                 } else if (info->implied) {
 454                         return_implies_state(info->name,
 455                                         info->implies_start, info->implies_end,
 456                                         &refcount_implied, info);
 457                 } else {
 458                         add_function_hook(info->name, &refcount_function, info);
 459                 }
 460         }
 461
 462         add_hook(&match_check_missed, END_FUNC_HOOK);
 463
 464         add_hook(&match_after_func, AFTER_FUNC_HOOK);
 465         add_hook(&match_save_states, INLINE_FN_START);
 466         add_hook(&match_restore_states, INLINE_FN_END);
 467 }