smatch_type_val.c

   1 /*
   2  * Copyright (C) 2013 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 /*
  19  * The plan here is to save all the possible values store to a given struct
  20  * member.
  21  *
  22  * We will load all the values in to the function_type_val table first then
  23  * run a script on that and load all the resulting values into the type_val
  24  * table.
  25  *
  26  * So in this file we want to take the union of everything assigned to the
  27  * struct member and insert it into the function_type_val at the end.
  28  *
  29  * You would think that we could use smatch_modification_hooks.c or
  30  * extra_modification_hook() here to get the information here but in the end we
  31  * need to code everything again a third time.
  32  *
  33  */
  34
  35 #include "smatch.h"
  36 #include "smatch_slist.h"
  37 #include "smatch_extra.h"
  38
  39 static int my_id;
  40
  41 struct stree_stack *fn_type_val_stack;
  42 struct stree *fn_type_val;
  43 struct stree *global_type_val;
  44
  45 static int get_vals(void *_db_vals, int argc, char **argv, char **azColName)
  46 {
  47         char **db_vals = _db_vals;
  48
  49         *db_vals = alloc_string(argv[0]);
  50         return 0;
  51 }
  52
  53 static void match_inline_start(struct expression *expr)
  54 {
  55         push_stree(&fn_type_val_stack, fn_type_val);
  56         fn_type_val = NULL;
  57 }
  58
  59 static void match_inline_end(struct expression *expr)
  60 {
  61         free_stree(&fn_type_val);
  62         fn_type_val = pop_stree(&fn_type_val_stack);
  63 }
  64
  65 struct expr_rl {
  66         struct expression *expr;
  67         struct range_list *rl;
  68 };
  69 static struct expr_rl cached_results[10];
  70 static int res_idx;
  71
  72 static int get_cached(struct expression *expr, struct range_list **rl, int *ret)
  73 {
  74         int i;
  75
  76         *ret = 0;
  77
  78         for (i = 0; i < ARRAY_SIZE(cached_results); i++) {
  79                 if (expr == cached_results[i].expr) {
  80                         if (cached_results[i].rl) {
  81                                 *rl = clone_rl(cached_results[i].rl);
  82                                 *ret = 1;
  83                         }
  84                         return 1;
  85                 }
  86         }
  87
  88         return 0;
  89 }
  90
  91 int get_db_type_rl(struct expression *expr, struct range_list **rl)
  92 {
  93         char *db_vals = NULL;
  94         char *member;
  95         struct range_list *tmp;
  96         struct symbol *type;
  97         int ret;
  98
  99         if (get_cached(expr, rl, &ret))
 100                 return ret;
 101
 102         member = get_member_name(expr);
 103         if (!member)
 104                 return 0;
 105
 106         res_idx = (res_idx + 1) % ARRAY_SIZE(cached_results);
 107         cached_results[res_idx].expr = expr;
 108         cached_results[res_idx].rl = NULL;
 109
 110         run_sql(get_vals, &db_vals,
 111                 "select value from type_value where type = '%s';", member);
 112         free_string(member);
 113         if (!db_vals)
 114                 return 0;
 115         type = get_type(expr);
 116         str_to_rl(type, db_vals, &tmp);
 117         free_string(db_vals);
 118         if (is_whole_rl(tmp))
 119                 return 0;
 120
 121         *rl = tmp;
 122         cached_results[res_idx].rl = clone_rl(tmp);
 123
 124         return 1;
 125 }
 126
 127 static void add_type_val(char *member, struct range_list *rl)
 128 {
 129         struct smatch_state *old, *add, *new;
 130
 131         member = alloc_string(member);
 132         old = get_state_stree(fn_type_val, my_id, member, NULL);
 133         add = alloc_estate_rl(rl);
 134         if (old)
 135                 new = merge_estates(old, add);
 136         else
 137                 new = add;
 138         set_state_stree(&fn_type_val, my_id, member, NULL, new);
 139 }
 140
 141 static void add_fake_type_val(char *member, struct range_list *rl, int ignore)
 142 {
 143         struct smatch_state *old, *add, *new;
 144
 145         member = alloc_string(member);
 146         old = get_state_stree(fn_type_val, my_id, member, NULL);
 147         if (old && strcmp(old->name, "min-max") == 0)
 148                 return;
 149         if (ignore && old && strcmp(old->name, "ignore") == 0)
 150                 return;
 151         add = alloc_estate_rl(rl);
 152         if (old) {
 153                 new = merge_estates(old, add);
 154         } else {
 155                 new = add;
 156                 if (ignore)
 157                         new->name = alloc_string("ignore");
 158                 else
 159                         new->name = alloc_string("min-max");
 160         }
 161         set_state_stree(&fn_type_val, my_id, member, NULL, new);
 162 }
 163
 164 static void add_global_type_val(char *member, struct range_list *rl)
 165 {
 166         struct smatch_state *old, *add, *new;
 167
 168         member = alloc_string(member);
 169         old = get_state_stree(global_type_val, my_id, member, NULL);
 170         add = alloc_estate_rl(rl);
 171         if (old)
 172                 new = merge_estates(old, add);
 173         else
 174                 new = add;
 175         new = clone_estate_perm(new);
 176         set_state_stree_perm(&global_type_val, my_id, member, NULL, new);
 177 }
 178
 179 static int has_link_cb(void *has_link, int argc, char **argv, char **azColName)
 180 {
 181         *(int *)has_link = 1;
 182         return 0;
 183 }
 184
 185 static int is_ignored_fake_assignment(void)
 186 {
 187         struct expression *expr;
 188         struct symbol *type;
 189         char *member_name;
 190         int has_link = 0;
 191
 192         expr = get_faked_expression();
 193         if (!expr || expr->type != EXPR_ASSIGNMENT)
 194                 return 0;
 195         if (!is_void_pointer(expr->right))
 196                 return 0;
 197         member_name = get_member_name(expr->right);
 198         if (!member_name)
 199                 return 0;
 200
 201         type = get_type(expr->left);
 202         if (!type || type->type != SYM_PTR)
 203                 return 0;
 204         type = get_real_base_type(type);
 205         if (!type || type->type != SYM_STRUCT)
 206                 return 0;
 207
 208         run_sql(has_link_cb, &has_link,
 209                 "select * from data_info where type = %d and data = '%s' and value = '%s';",
 210                 TYPE_LINK, member_name, type_to_str(type));
 211         return has_link;
 212 }
 213
 214 static int is_container_of(void)
 215 {
 216         /* We already check the macro name in is_ignored_macro() */
 217         struct expression *expr;
 218         int offset;
 219
 220         expr = get_faked_expression();
 221         if (!expr || expr->type != EXPR_ASSIGNMENT)
 222                 return 0;
 223
 224         offset = get_offset_from_container_of(expr->right);
 225         if (offset < 0)
 226                 return 0;
 227         return 1;
 228 }
 229
 230 static int is_ignored_macro(void)
 231 {
 232         struct expression *expr;
 233         char *name;
 234
 235         expr = get_faked_expression();
 236         if (!expr || expr->type != EXPR_ASSIGNMENT)
 237                 return 0;
 238         name = get_macro_name(expr->right->pos);
 239         if (!name)
 240                 return 0;
 241         if (strcmp(name, "container_of") == 0)
 242                 return 1;
 243         if (strcmp(name, "rb_entry") == 0)
 244                 return 1;
 245         if (strcmp(name, "list_entry") == 0)
 246                 return 1;
 247         if (strcmp(name, "list_first_entry") == 0)
 248                 return 1;
 249         if (strcmp(name, "hlist_entry") == 0)
 250                 return 1;
 251         if (strstr(name, "for_each"))
 252                 return 1;
 253         return 0;
 254 }
 255
 256 static int is_ignored_function(void)
 257 {
 258         struct expression *expr;
 259
 260         expr = get_faked_expression();
 261         if (!expr || expr->type != EXPR_ASSIGNMENT)
 262                 return 0;
 263         expr = strip_expr(expr->right);
 264         if (!expr || expr->type != EXPR_CALL || expr->fn->type != EXPR_SYMBOL)
 265                 return 0;
 266
 267         if (sym_name_is("kmalloc", expr->fn))
 268                 return 1;
 269         if (sym_name_is("netdev_priv", expr->fn))
 270                 return 1;
 271         if (sym_name_is("dev_get_drvdata", expr->fn))
 272                 return 1;
 273
 274         return 0;
 275 }
 276
 277 static int is_uncasted_pointer_assign(void)
 278 {
 279         struct expression *expr;
 280         struct symbol *left_type, *right_type;
 281
 282         expr = get_faked_expression();
 283         if (!expr)
 284                 return 0;
 285         if (expr->type == EXPR_PREOP || expr->type == EXPR_POSTOP) {
 286                 if (expr->op == SPECIAL_INCREMENT || expr->op == SPECIAL_DECREMENT)
 287                         return 1;
 288         }
 289         if (expr->type != EXPR_ASSIGNMENT)
 290                 return 0;
 291         left_type = get_type(expr->left);
 292         right_type = get_type(expr->right);
 293
 294         if (!left_type || !right_type)
 295                 return 0;
 296
 297         if (left_type->type != SYM_PTR &&
 298             left_type->type != SYM_ARRAY)
 299                 return 0;
 300         if (right_type->type != SYM_PTR &&
 301             right_type->type != SYM_ARRAY)
 302                 return 0;
 303         left_type = get_real_base_type(left_type);
 304         right_type = get_real_base_type(right_type);
 305
 306         if (left_type == right_type)
 307                 return 1;
 308         return 0;
 309 }
 310
 311 static int set_param_type(void *_type_str, int argc, char **argv, char **azColName)
 312 {
 313         char **type_str = _type_str;
 314         static char type_buf[128];
 315
 316         if (*type_str) {
 317                 if (strcmp(*type_str, argv[0]) == 0)
 318                         return 0;
 319                 strncpy(type_buf, "unknown", sizeof(type_buf));
 320                 return 0;
 321         }
 322         strncpy(type_buf, argv[0], sizeof(type_buf));
 323         *type_str = type_buf;
 324
 325         return 0;
 326 }
 327
 328 static char *db_get_parameter_type(int param)
 329 {
 330         char *ret = NULL;
 331
 332         if (!cur_func_sym)
 333                 return NULL;
 334
 335         run_sql(set_param_type, &ret,
 336                 "select value from fn_data_link where "
 337                 "file = '%s' and function = '%s' and static = %d and type = %d and parameter = %d and key = '$';",
 338                 (cur_func_sym->ctype.modifiers & MOD_STATIC) ? get_base_file() : "extern",
 339                 cur_func_sym->ident->name,
 340                 !!(cur_func_sym->ctype.modifiers & MOD_STATIC),
 341                 PASSES_TYPE, param);
 342
 343         return ret;
 344 }
 345
 346 static int is_uncasted_fn_param_from_db(void)
 347 {
 348         struct expression *expr, *right;
 349         struct symbol *left_type;
 350         char left_type_name[128];
 351         int param;
 352         char *right_type_name;
 353         static struct expression *prev_expr;
 354         static int prev_ans;
 355
 356         expr = get_faked_expression();
 357
 358         if (expr == prev_expr)
 359                 return prev_ans;
 360         prev_expr = expr;
 361         prev_ans = 0;
 362
 363         if (!expr || expr->type != EXPR_ASSIGNMENT)
 364                 return 0;
 365         left_type = get_type(expr->left);
 366         if (!left_type || left_type->type != SYM_PTR)
 367                 return 0;
 368         left_type = get_real_base_type(left_type);
 369         if (!left_type || left_type->type != SYM_STRUCT)
 370                 return 0;
 371         snprintf(left_type_name, sizeof(left_type_name), "%s", type_to_str(left_type));
 372
 373         right = strip_expr(expr->right);
 374         param = get_param_num(right);
 375         if (param < 0)
 376                 return 0;
 377         right_type_name = db_get_parameter_type(param);
 378         if (!right_type_name)
 379                 return 0;
 380
 381         if (strcmp(right_type_name, left_type_name) == 0) {
 382                 prev_ans = 1;
 383                 return 1;
 384         }
 385
 386         return 0;
 387 }
 388
 389 static void match_assign_value(struct expression *expr)
 390 {
 391         char *member, *right_member;
 392         struct range_list *rl;
 393         struct symbol *type;
 394
 395         type = get_type(expr->left);
 396         if (type && type->type == SYM_STRUCT)
 397                 return;
 398
 399         member = get_member_name(expr->left);
 400         if (!member)
 401                 return;
 402
 403         /* if we're saying foo->mtu = bar->mtu then that doesn't add information */
 404         right_member = get_member_name(expr->right);
 405         if (right_member && strcmp(right_member, member) == 0)
 406                 goto free;
 407
 408         if (is_fake_call(expr->right)) {
 409                 if (is_ignored_macro())
 410                         goto free;
 411                 if (is_ignored_function())
 412                         goto free;
 413                 if (is_uncasted_pointer_assign())
 414                         goto free;
 415                 if (is_uncasted_fn_param_from_db())
 416                         goto free;
 417                 if (is_container_of())
 418                         goto free;
 419                 add_fake_type_val(member, alloc_whole_rl(get_type(expr->left)), is_ignored_fake_assignment());
 420                 goto free;
 421         }
 422
 423         if (expr->op == '=') {
 424                 get_absolute_rl(expr->right, &rl);
 425                 rl = cast_rl(type, rl);
 426         } else {
 427                 /*
 428                  * This is a bit cheating.  We order it so this will already be set
 429                  * by smatch_extra.c and we just look up the value.
 430                  */
 431                 get_absolute_rl(expr->left, &rl);
 432         }
 433         add_type_val(member, rl);
 434 free:
 435         free_string(right_member);
 436         free_string(member);
 437 }
 438
 439 /*
 440  * If we too:  int *p = &my_struct->member then abandon all hope of tracking
 441  * my_struct->member.
 442  */
 443 static void match_assign_pointer(struct expression *expr)
 444 {
 445         struct expression *right;
 446         char *member;
 447         struct range_list *rl;
 448         struct symbol *type;
 449
 450         right = strip_expr(expr->right);
 451         if (right->type != EXPR_PREOP || right->op != '&')
 452                 return;
 453         right = strip_expr(right->unop);
 454
 455         member = get_member_name(right);
 456         if (!member)
 457                 return;
 458         type = get_type(right);
 459         rl = alloc_whole_rl(type);
 460         add_type_val(member, rl);
 461         free_string(member);
 462 }
 463
 464 static void match_global_assign(struct expression *expr)
 465 {
 466         char *member;
 467         struct range_list *rl;
 468         struct symbol *type;
 469
 470         type = get_type(expr->left);
 471         if (type && (type->type == SYM_ARRAY || type->type == SYM_STRUCT))
 472                 return;
 473         member = get_member_name(expr->left);
 474         if (!member)
 475                 return;
 476         get_absolute_rl(expr->right, &rl);
 477         rl = cast_rl(type, rl);
 478         add_global_type_val(member, rl);
 479         free_string(member);
 480 }
 481
 482 static void unop_expr(struct expression *expr)
 483 {
 484         struct range_list *rl;
 485         char *member;
 486
 487         if (expr->op != SPECIAL_DECREMENT && expr->op != SPECIAL_INCREMENT)
 488                 return;
 489
 490         expr = strip_expr(expr->unop);
 491         member = get_member_name(expr);
 492         if (!member)
 493                 return;
 494         rl = alloc_whole_rl(get_type(expr));
 495         add_type_val(member, rl);
 496         free_string(member);
 497 }
 498
 499 static void asm_expr(struct statement *stmt)
 500 {
 501         struct expression *expr;
 502         struct range_list *rl;
 503         char *member;
 504         int state = 0;
 505
 506         FOR_EACH_PTR(stmt->asm_outputs, expr) {
 507                 switch (state) {
 508                 case 0: /* identifier */
 509                 case 1: /* constraint */
 510                         state++;
 511                         continue;
 512                 case 2: /* expression */
 513                         state = 0;
 514                         member = get_member_name(expr);
 515                         if (!member)
 516                                 continue;
 517                         rl = alloc_whole_rl(get_type(expr));
 518                         add_type_val(member, rl);
 519                         free_string(member);
 520                         continue;
 521                 }
 522         } END_FOR_EACH_PTR(expr);
 523 }
 524
 525 static void db_param_add(struct expression *expr, int param, char *key, char *value)
 526 {
 527         struct expression *arg;
 528         struct symbol *type;
 529         struct range_list *rl;
 530         char *member;
 531
 532         if (strcmp(key, "*$") != 0)
 533                 return;
 534
 535         while (expr->type == EXPR_ASSIGNMENT)
 536                 expr = strip_expr(expr->right);
 537         if (expr->type != EXPR_CALL)
 538                 return;
 539
 540         arg = get_argument_from_call_expr(expr->args, param);
 541         arg = strip_expr(arg);
 542         if (!arg)
 543                 return;
 544         type = get_member_type_from_key(arg, key);
 545         if (arg->type != EXPR_PREOP || arg->op != '&')
 546                 return;
 547         arg = strip_expr(arg->unop);
 548
 549         member = get_member_name(arg);
 550         if (!member)
 551                 return;
 552         call_results_to_rl(expr, type, value, &rl);
 553         add_type_val(member, rl);
 554         free_string(member);
 555 }
 556
 557 static void match_end_func_info(struct symbol *sym)
 558 {
 559         struct sm_state *sm;
 560
 561         FOR_EACH_SM(fn_type_val, sm) {
 562                 sql_insert_function_type_value(sm->name, sm->state->name);
 563         } END_FOR_EACH_SM(sm);
 564 }
 565
 566 static void clear_cache(struct symbol *sym)
 567 {
 568         memset(cached_results, 0, sizeof(cached_results));
 569 }
 570
 571 static void match_after_func(struct symbol *sym)
 572 {
 573         free_stree(&fn_type_val);
 574 }
 575
 576 static void match_end_file(struct symbol_list *sym_list)
 577 {
 578         struct sm_state *sm;
 579
 580         FOR_EACH_SM(global_type_val, sm) {
 581                 sql_insert_function_type_value(sm->name, sm->state->name);
 582         } END_FOR_EACH_SM(sm);
 583 }
 584
 585 void register_type_val(int id)
 586 {
 587         my_id = id;
 588         add_hook(&clear_cache, AFTER_FUNC_HOOK);
 589
 590         if (!option_info)
 591                 return;
 592
 593         add_hook(&match_assign_value, ASSIGNMENT_HOOK_AFTER);
 594         add_hook(&match_assign_pointer, ASSIGNMENT_HOOK);
 595         add_hook(&unop_expr, OP_HOOK);
 596         add_hook(&asm_expr, ASM_HOOK);
 597         select_return_states_hook(PARAM_ADD, &db_param_add);
 598         select_return_states_hook(PARAM_SET, &db_param_add);
 599
 600
 601         add_hook(&match_inline_start, INLINE_FN_START);
 602         add_hook(&match_inline_end, INLINE_FN_END);
 603
 604         add_hook(&match_end_func_info, END_FUNC_HOOK);
 605         add_hook(&match_after_func, AFTER_FUNC_HOOK);
 606
 607         add_hook(&match_global_assign, GLOBAL_ASSIGNMENT_HOOK);
 608         add_hook(&match_end_file, END_FILE_HOOK);
 609 }