smatch_units.c

   1 /*
   2  * Copyright (C) 2018 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 "smatch.h"
  19 #include "smatch_slist.h"
  20
  21 static int my_id;
  22
  23 GLOBAL_STATE(unit_bit);
  24 GLOBAL_STATE(unit_byte);
  25 GLOBAL_STATE(unit_array_size);
  26 GLOBAL_STATE(unit_long);
  27 GLOBAL_STATE(unit_page);
  28 GLOBAL_STATE(unit_msec);
  29 GLOBAL_STATE(unit_ns);
  30 GLOBAL_STATE(unit_jiffy);
  31
  32 struct type_info {
  33         const char *name;
  34         int type;
  35         int param;
  36         const char *key;
  37         const char *value;
  38 };
  39
  40 static struct type_info func_table[] = {
  41         { "unit_msecs_to_jiffies_timeout", UNITS, -1, "$", "unit_jiffy" },
  42         { "round_jiffies_up_relative", UNITS, -1, "$", "unit_jiffy" },
  43 };
  44
  45 static struct smatch_state *str_to_units(const char *str)
  46 {
  47         if (!str)
  48                 return NULL;
  49
  50         if (strcmp(str, "unit_bit") == 0)
  51                 return &unit_bit;
  52         if (strcmp(str, "unit_byte") == 0)
  53                 return &unit_byte;
  54         if (strcmp(str, "unit_page") == 0)
  55                 return &unit_page;
  56         if (strcmp(str, "unit_msec") == 0)
  57                 return &unit_msec;
  58         if (strcmp(str, "unit_jiffy") == 0)
  59                 return &unit_jiffy;
  60         if (strcmp(str, "unit_long") == 0)
  61                 return &unit_long;
  62         if (strcmp(str, "unit_array_size") == 0)
  63                 return &unit_array_size;
  64         if (strcmp(str, "unknown") == 0)
  65                 return NULL;
  66
  67         return NULL;
  68 }
  69
  70 static struct smatch_state *get_units_from_type(struct expression *expr);
  71
  72 static struct smatch_state *merge_units(struct smatch_state *s1, struct smatch_state *s2)
  73 {
  74         if (s1 == &undefined)
  75                 return s2;
  76         if (s2 == &undefined)
  77                 return s1;
  78         return &merged;
  79 }
  80
  81 static bool is_ignored_type(char *name)
  82 {
  83         if (!name)
  84                 return false;
  85         if (strcmp(name, "(union anonymous)->__val") == 0)
  86                 return true;
  87         if (strncmp(name, "(struct fs_parse_result)", 24) == 0)
  88                 return true;
  89         return false;
  90 }
  91
  92 static void store_type_in_db(struct expression *expr, struct smatch_state *state)
  93 {
  94         char *member;
  95
  96         member = get_member_name(expr);
  97         if (!member)
  98                 return;
  99         if (is_ignored_type(member))
 100                 return;
 101
 102         sql_insert_cache(type_info, "0x%llx, %d, '%s', '%s'", get_base_file_id(), UNITS, member, state->name);
 103 }
 104
 105 static void set_units(struct expression *expr, struct smatch_state *state)
 106 {
 107         if (!state)
 108                 return;
 109
 110         set_state_expr(my_id, expr, state);
 111         store_type_in_db(expr, state);
 112 }
 113
 114 static bool is_PAGE_SHIFT(struct expression *expr)
 115 {
 116         char *macro;
 117
 118         macro = get_macro_name(expr->pos);
 119         if (macro && strcmp(macro, "PAGE_SHIFT") == 0)
 120                 return true;
 121         return false;
 122 }
 123
 124 static bool is_PAGE_SIZE(struct expression *expr)
 125 {
 126         char *macro;
 127
 128         macro = get_macro_name(expr->pos);
 129         if (macro && strcmp(macro, "PAGE_SIZE") == 0)
 130                 return true;
 131         return false;
 132 }
 133
 134 static bool is_BITS_PER_LONG(struct expression *expr)
 135 {
 136         char *macro;
 137
 138         macro = get_macro_name(expr->pos);
 139         if (macro && strcmp(macro, "BITS_PER_LONG") == 0)
 140                 return true;
 141         return false;
 142 }
 143
 144 static struct smatch_state *binop_helper(struct expression *left, int op, struct expression *right)
 145 {
 146         struct smatch_state *left_state, *right_state;
 147         sval_t val;
 148
 149         switch(op) {
 150         case '-':
 151                 // subtracting pointers gives unit_byte
 152                 /* fall through */
 153         case '+':
 154                 left_state = get_units(left);
 155                 right_state = get_units(right);
 156                 if (left_state == &unit_array_size ||
 157                     right_state == &unit_array_size)
 158                         return NULL;
 159
 160                 return left_state ? left_state : right_state;
 161         case '*':
 162                 /* FIXME: A multiply is almost always bytes but it can be bits. */
 163                 if (is_PAGE_SIZE(right))
 164                         return &unit_byte;
 165                 if (!get_implied_value(right, &val))
 166                         return NULL;
 167                 /* 4096 is almost always a unit_page -> bytes converstion */
 168                 if (val.value == 4096)
 169                         return &unit_byte;
 170                 return NULL;
 171         case '/':
 172                 if (is_BITS_PER_LONG(right))
 173                         return &unit_long;
 174                 if (is_PAGE_SIZE(right))
 175                         return &unit_page;
 176                 if (!get_implied_value(right, &val))
 177                         return NULL;
 178                 if (val.value == 4096)
 179                         return &unit_page;
 180                 return NULL;
 181         case SPECIAL_LEFTSHIFT:
 182                 if (is_PAGE_SHIFT(right))
 183                         return &unit_byte;
 184                 return NULL;
 185         case SPECIAL_RIGHTSHIFT:
 186                 if (is_PAGE_SHIFT(right))
 187                         return &unit_page;
 188                 return NULL;
 189         }
 190         return NULL;
 191 }
 192
 193 static struct smatch_state *get_units_binop(struct expression *expr)
 194 {
 195         return binop_helper(expr->left, expr->op, expr->right);
 196 }
 197
 198 static struct smatch_state *get_units_call(struct expression *expr)
 199 {
 200         expr = strip_expr(expr);
 201         if (!expr || expr->type != EXPR_CALL)
 202                 return NULL;
 203
 204         if (sym_name_is("unit_msecs_to_jiffies", expr->fn))
 205                 return &unit_jiffy;
 206         if (sym_name_is("jiffies_to_unit_msecs", expr->fn))
 207                 return &unit_msec;
 208
 209         return NULL;
 210 }
 211
 212 static int db_units(void *_units, int argc, char **argv, char **azColName)
 213 {
 214         char **units = _units;
 215
 216         if (*units) {
 217                 if (strcmp(*units, argv[0]) == 0)
 218                         return 0;
 219                 free_string(*units);
 220                 *units = alloc_string("unknown");
 221                 return 0;
 222
 223         }
 224         *units = alloc_string(argv[0]);
 225         return 0;
 226 }
 227
 228 static struct smatch_state *get_units_from_type(struct expression *expr)
 229 {
 230         char *member;
 231         char *units = NULL;
 232         struct smatch_state *ret = NULL;
 233
 234         member = get_member_name(expr);
 235         if (!member)
 236                 return NULL;
 237         if (strcmp(member, "(struct vm_area_struct)->vm_pgoff") == 0)
 238                 return &unit_page;
 239         cache_sql(&db_units, &units, "select value from type_info where type = %d and key = '%s';",
 240                   UNITS, member);
 241         run_sql(&db_units, &units, "select value from type_info where type = %d and key = '%s';",
 242                 UNITS, member);
 243         free_string(member);
 244         if (!units)
 245                 return NULL;
 246
 247         ret = str_to_units(units);
 248
 249         free_string(units);
 250
 251         return ret;
 252 }
 253
 254 struct smatch_state *get_units(struct expression *expr)
 255 {
 256         struct smatch_state *state;
 257         char *ident;
 258
 259         expr = strip_expr(expr);
 260         if (!expr)
 261                 return NULL;
 262
 263         if (expr->type == EXPR_PTRSIZEOF ||
 264             expr->type == EXPR_SIZEOF)
 265                 return &unit_byte;
 266
 267         ident = pos_ident(expr->pos);
 268         if (ident) {
 269                 if (strcmp(ident, "sizeof") == 0 ||
 270                     strcmp(ident, "PAGE_SIZE") == 0)
 271                         return &unit_byte;
 272                 if (strcmp(ident, "jiffies") == 0)
 273                         return &unit_jiffy;
 274                 if (strcmp(ident, "BITS_PER_LONG") == 0)
 275                         return &unit_bit;
 276                 if (strcmp(ident, "BITS_PER_LONG_LONG") == 0)
 277                         return &unit_bit;
 278                 if (strcmp(ident, "ARRAY_SIZE") == 0)
 279                         return &unit_array_size;
 280         }
 281
 282         if (expr->type == EXPR_BINOP)
 283                 return get_units_binop(expr);
 284
 285         if (expr->type == EXPR_CALL)
 286                 return get_units_call(expr);
 287
 288         state = get_state_expr(my_id, expr);
 289         if (state == &merged || state == &undefined)
 290                 return NULL;
 291         if (state)
 292                 return state;
 293
 294         return get_units_from_type(expr);
 295 }
 296
 297 bool is_array_size_units(struct expression *expr)
 298 {
 299         return get_units(expr) == &unit_array_size;
 300 }
 301
 302 static void match_allocation(struct expression *expr,
 303                              const char *name, struct symbol *sym,
 304                              struct allocation_info *info)
 305 {
 306         struct expression *right, *left;
 307
 308         if (info->nr_elems && info->elem_size) {
 309                 left = info->nr_elems;
 310                 right = info->elem_size;
 311         } else if (info->total_size &&
 312                    info->total_size->type == EXPR_BINOP &&
 313                    info->total_size->op == '*') {
 314                 left = strip_expr(info->total_size->left);
 315                 right = strip_expr(info->total_size->right);
 316         } else {
 317                 return;
 318         }
 319
 320         if (get_units(left) == &unit_byte)
 321                 set_units(right, &unit_array_size);
 322         if (get_units(right) == &unit_byte)
 323                 set_units(left, &unit_array_size);
 324 }
 325
 326 static void match_binop_set(struct expression *expr)
 327 {
 328         struct smatch_state *left, *right;
 329         struct symbol *type;
 330
 331         if (expr->op == SPECIAL_LEFTSHIFT && is_PAGE_SHIFT(expr->right)) {
 332                 set_units(expr->left, &unit_page);
 333                 return;
 334         }
 335
 336         if (expr->op == SPECIAL_RIGHTSHIFT && is_PAGE_SHIFT(expr->right)) {
 337                 set_units(expr->left, &unit_byte);
 338                 return;
 339         }
 340
 341         if (expr->op != '+' && expr->op != '-')
 342                 return;
 343
 344         type = get_type(expr->left);
 345         if (type && (type->type == SYM_PTR || type->type == SYM_ARRAY))
 346                 return;
 347
 348         left = get_units(expr->left);
 349         right = get_units(expr->right);
 350
 351         if (left && !right)
 352                 set_units(expr->right, left);
 353         if (right && !left)
 354                 set_units(expr->left, right);
 355 }
 356
 357 static void match_condition_set(struct expression *expr)
 358 {
 359         struct smatch_state *left, *right;
 360
 361         if (expr->type != EXPR_COMPARE)
 362                 return;
 363
 364         left = get_units(expr->left);
 365         right = get_units(expr->right);
 366
 367         if (left && !right)
 368                 set_units(expr->right, left);
 369         if (right && !left)
 370                 set_units(expr->left, right);
 371 }
 372
 373 static void match_assign(struct expression *expr)
 374 {
 375         struct smatch_state *state = NULL;
 376
 377         if (__in_fake_assign)
 378                 return;
 379
 380         switch(expr->op) {
 381         case '=':
 382                 state = get_units(expr->right);
 383                 break;
 384         case SPECIAL_SHR_ASSIGN:
 385         case SPECIAL_SHL_ASSIGN:
 386         case SPECIAL_DIV_ASSIGN:
 387         case SPECIAL_MUL_ASSIGN:
 388                 state = binop_helper(expr->left, op_remove_assign(expr->op),
 389                                      expr->right);
 390         }
 391
 392         if (state)
 393                 set_units(expr->left, state);
 394 //      else
 395 //              clear_units(expr->left);
 396 }
 397
 398 static void set_implied_units(struct expression *call, struct expression *arg, char *key, char *value)
 399 {
 400         struct smatch_state *state;
 401         struct symbol *sym;
 402         char *name;
 403
 404         state = str_to_units(value);
 405         if (!state)
 406                 return;
 407         name = get_variable_from_key(arg, key, &sym);
 408         if (!name || !sym)
 409                 goto free;
 410         set_state(my_id, name, sym, state);
 411 free:
 412         free_string(name);
 413 }
 414
 415 static void set_param_units(const char *name, struct symbol *sym, char *key, char *value)
 416 {
 417         struct smatch_state *state;
 418
 419         state = str_to_units(value);
 420         if (!state)
 421                 return;
 422         set_state(my_id, sym->ident->name, sym, state);
 423 }
 424
 425 static void set_param_units_from_table(struct expression *expr, const char *name, struct symbol *sym, void *data)
 426 {
 427         const char *value = data;
 428         struct smatch_state *state;
 429
 430         state = str_to_units(value);
 431         if (!state)
 432                 return;
 433         set_state(my_id, name, sym, state);
 434 }
 435
 436 static void match_call_info(struct expression *expr)
 437 {
 438         struct expression *arg;
 439         struct smatch_state *state;
 440         char *fn_name;
 441         int param = -1;
 442
 443         if (expr->fn->type != EXPR_SYMBOL)
 444                 return;
 445         fn_name = expr_to_var(expr->fn);
 446         if (!fn_name)
 447                 return;
 448
 449         FOR_EACH_PTR(expr->args, arg) {
 450                 param++;
 451                 state = get_units(arg);
 452                 if (!state)
 453                         continue;
 454 //              sql_insert_cache(return_implies, "0x%llx, '%s', 0, %d, %d, %d, '%s', '%s'",
 455 //                               get_base_file_id(), fn_name, is_static(expr->fn), UNITS, param, "$", state->name);
 456                 sql_insert_caller_info(expr, UNITS, param, "$", state->name);
 457
 458         } END_FOR_EACH_PTR(arg);
 459
 460         free_string(fn_name);
 461 }
 462
 463 static void process_states(void)
 464 {
 465         struct symbol *arg;
 466         struct smatch_state *state, *start_state;
 467         int param = -1;
 468
 469         FOR_EACH_PTR(cur_func_sym->ctype.base_type->arguments, arg) {
 470                 param++;
 471                 state = get_state(my_id, arg->ident->name, arg);
 472                 if (!state || state == &merged || state == &undefined)
 473                         continue;
 474                 start_state = get_state_stree(get_start_states(), my_id, arg->ident->name, arg);
 475                 if (state == start_state)
 476                         continue;
 477                 sql_insert_cache(return_implies, "0x%llx, '%s', 0, %d, %d, %d, '%s', '%s'",
 478                                  get_base_file_id(), get_function(), fn_static(), UNITS, param, "$", state->name);
 479         } END_FOR_EACH_PTR(arg);
 480 }
 481
 482 char *get_unit_str(struct expression *expr)
 483 {
 484         struct smatch_state *state;
 485
 486         state = get_units(expr);
 487         if (!state)
 488                 return NULL;
 489         return (char *)state->name;
 490 }
 491
 492 void register_units(int id)
 493 {
 494         struct type_info *info;
 495         int i;
 496
 497         my_id = id;
 498
 499         for (i = 0; i < ARRAY_SIZE(func_table); i++) {
 500                 info = &func_table[i];
 501                 add_function_param_key_hook(info->name,
 502                                             set_param_units_from_table,
 503                                             info->param, info->key,
 504                                             (void *)info->value);
 505         }
 506
 507         add_merge_hook(my_id, &merge_units);
 508
 509         add_hook(&match_binop_set, BINOP_HOOK);
 510         add_hook(&match_condition_set, CONDITION_HOOK);
 511         add_hook(&match_assign, ASSIGNMENT_HOOK);
 512         add_hook(&match_call_info, FUNCTION_CALL_HOOK);
 513         all_return_states_hook(&process_states);
 514
 515         select_return_implies_hook(UNITS, &set_implied_units);
 516         select_caller_info_hook(&set_param_units, UNITS);
 517
 518         add_allocation_hook(&match_allocation);
 519 }