smatch_mtag_data.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 /*
  19  * What we're doing here is saving all the possible values for static variables.
  20  * Later on we might do globals as well.
  21  *
  22  */
  23
  24 #include "smatch.h"
  25 #include "smatch_slist.h"
  26 #include "smatch_extra.h"
  27
  28 static int my_id;
  29 static struct stree *vals;
  30
  31 static int save_rl(void *_rl, int argc, char **argv, char **azColName)
  32 {
  33         unsigned long *rl = _rl;
  34
  35         *rl = strtoul(argv[0], NULL, 10);
  36         return 0;
  37 }
  38
  39 static struct range_list *select_orig(mtag_t tag, int offset)
  40 {
  41         struct range_list *rl = NULL;
  42
  43         mem_sql(&save_rl, &rl, "select value from mtag_data where tag = %lld and offset = %d;",
  44                 tag, offset);
  45         return rl;
  46 }
  47
  48 static int is_kernel_param(const char *name)
  49 {
  50         struct sm_state *tmp;
  51         char buf[256];
  52
  53         /*
  54          * I'm ignoring these because otherwise Smatch thinks that kernel
  55          * parameters are always set to the default.
  56          *
  57          */
  58
  59         if (option_project != PROJ_KERNEL)
  60                 return 0;
  61
  62         snprintf(buf, sizeof(buf), "__param_%s.arg", name);
  63
  64         FOR_EACH_SM(vals, tmp) {
  65                 if (strcmp(tmp->name, buf) == 0)
  66                         return 1;
  67         } END_FOR_EACH_SM(tmp);
  68
  69         return 0;
  70 }
  71
  72 static bool is_ignored_macro(struct expression *expr)
  73 {
  74         char *macro;
  75
  76         macro = get_macro_name(expr->pos);
  77         if (!macro)
  78                 return false;
  79         if (strcmp(macro, "EXPORT_SYMBOL") == 0)
  80                 return true;
  81         return false;
  82 }
  83
  84 static bool is_head_next(struct expression *expr)
  85 {
  86         struct symbol *type;
  87
  88         /* Smatch thinks head->next == head is always true.  *sad face* */
  89
  90         if (option_project != PROJ_KERNEL)
  91                 return false;
  92
  93         if (expr->type != EXPR_DEREF)
  94                 return false;
  95         if (!expr->member || !expr->member->name ||
  96             strcmp(expr->member->name, "next") != 0)
  97                 return false;
  98
  99         type = get_type(expr->deref);
 100         if (!type)
 101                 return false;
 102         if (type->type == SYM_PTR)
 103                 type = get_real_base_type(type);
 104         if (type->type != SYM_STRUCT)
 105                 return false;
 106         if (!type->ident || !type->ident->name ||
 107             strcmp(type->ident->name, "list_head") != 0)
 108                 return false;
 109         return true;
 110 }
 111
 112 mtag_t ignored_mtag;
 113 static bool is_ignored_tag(mtag_t tag)
 114 {
 115         if (tag == ignored_mtag)
 116                 return true;
 117         return false;
 118 }
 119
 120 static void insert_mtag_data(mtag_t tag, int offset, struct range_list *rl)
 121 {
 122         if (in_fake_env)
 123                 return;
 124         if (is_ignored_tag(tag))
 125                 return;
 126
 127         rl = clone_rl_permanent(rl);
 128
 129         mem_sql(NULL, NULL, "delete from mtag_data where tag = %lld and offset = %d and type = %d",
 130                 tag, offset, DATA_VALUE);
 131         mem_sql(NULL, NULL, "insert into mtag_data values (%lld, %d, %d, '%lu');",
 132                 tag, offset, DATA_VALUE, (unsigned long)rl);
 133 }
 134
 135 static bool invalid_type(struct symbol *type)
 136 {
 137         if (!type)
 138                 return true;
 139         if (type == &void_ctype)
 140                 return true;
 141         if (type->type == SYM_STRUCT ||
 142             type->type == SYM_ARRAY ||
 143             type->type == SYM_UNION)
 144                 return true;
 145         return false;
 146 }
 147
 148 static bool parent_is_fresh_alloc(struct expression *expr)
 149 {
 150         struct symbol *sym;
 151
 152         sym = expr_to_sym(expr);
 153         if (!sym || !sym->ident)
 154                 return false;
 155         return is_fresh_alloc_var_sym(sym->ident->name, sym);
 156 }
 157
 158 void update_mtag_data(struct expression *expr, struct smatch_state *state)
 159 {
 160         struct range_list *orig, *new;
 161         struct symbol *type;
 162         char *name;
 163         mtag_t tag;
 164         int offset;
 165
 166         if (!expr)
 167                 return;
 168         if (is_ignored_macro(expr))
 169                 return;
 170         if (is_head_next(expr))
 171                 return;
 172         name = expr_to_var(expr);
 173         if (is_kernel_param(name)) {
 174                 free_string(name);
 175                 return;
 176         }
 177         free_string(name);
 178
 179         if (!expr_to_mtag_offset(expr, &tag, &offset))
 180                 return;
 181
 182         type = get_type(expr);
 183         if (offset == 0 && invalid_type(type))
 184                 return;
 185
 186         if (parent_is_fresh_alloc(expr))
 187                 orig = NULL;
 188         else
 189                 orig = select_orig(tag, offset);
 190         new = rl_union(orig, estate_rl(state));
 191         insert_mtag_data(tag, offset, new);
 192 }
 193
 194 static void match_global_assign(struct expression *expr)
 195 {
 196         struct range_list *rl;
 197         mtag_t tag;
 198         int offset;
 199         char *name;
 200
 201         if (is_ignored_macro(expr))
 202                 return;
 203         if (is_head_next(expr->left))
 204                 return;
 205         name = expr_to_var(expr->left);
 206         if (is_kernel_param(name)) {
 207                 free_string(name);
 208                 return;
 209         }
 210         free_string(name);
 211
 212         if (!expr_to_mtag_offset(expr->left, &tag, &offset))
 213                 return;
 214
 215         get_absolute_rl(expr->right, &rl);
 216         insert_mtag_data(tag, offset, rl);
 217 }
 218
 219 static int save_mtag_data(void *_unused, int argc, char **argv, char **azColName)
 220 {
 221         struct range_list *rl;
 222
 223         if (argc != 4) {
 224                 sm_msg("Error saving mtag data");
 225                 return 0;
 226         }
 227         if (!option_info)
 228                 return 0;
 229
 230         rl = (struct range_list *)strtoul(argv[3], NULL, 10);
 231         sm_msg("SQL: insert or ignore into mtag_data values ('%s', '%s', '%s', '%s');",
 232                argv[0], argv[1], argv[2], show_rl(rl));
 233
 234         return 0;
 235 }
 236
 237 static void match_end_file(struct symbol_list *sym_list)
 238 {
 239         mem_sql(&save_mtag_data, NULL, "select * from mtag_data where type = %d;",
 240                 DATA_VALUE);
 241 }
 242
 243 struct db_info {
 244         struct symbol *type;
 245         struct range_list *rl;
 246 };
 247
 248 static int get_vals(void *_db_info, int argc, char **argv, char **azColName)
 249 {
 250         struct db_info *db_info = _db_info;
 251         struct range_list *tmp;
 252
 253         str_to_rl(db_info->type, argv[0], &tmp);
 254         if (db_info->rl)
 255                 db_info->rl = rl_union(db_info->rl, tmp);
 256         else
 257                 db_info->rl = tmp;
 258
 259         return 0;
 260 }
 261
 262 struct db_cache_results {
 263         mtag_t tag;
 264         struct range_list *rl;
 265 };
 266 static struct db_cache_results cached_results[8];
 267
 268 static int get_rl_from_mtag_offset(mtag_t tag, int offset, struct symbol *type, struct range_list **rl)
 269 {
 270         struct db_info db_info = {};
 271         mtag_t merged = tag | offset;
 272         struct range_list *mem_rl;
 273         static int idx;
 274         int i;
 275
 276         *rl = NULL;
 277
 278         for (i = 0; i < ARRAY_SIZE(cached_results); i++) {
 279                 if (merged == cached_results[i].tag) {
 280                         if (cached_results[i].rl) {
 281                                 *rl = cached_results[i].rl;
 282                                 return 1;
 283                         }
 284                         return 0;
 285                 }
 286         }
 287
 288         mem_rl = select_orig(tag, offset);
 289         if (is_whole_rl(mem_rl))
 290                 goto update_cache;
 291
 292         db_info.type = type;
 293         run_sql(get_vals, &db_info,
 294                 "select value from mtag_data where tag = %lld and offset = %d and type = %d;",
 295                 tag, offset, DATA_VALUE);
 296         if (!db_info.rl)
 297                 goto update_cache;
 298         db_info.rl = rl_union(mem_rl, db_info.rl);
 299         if (is_whole_rl(db_info.rl))
 300                 goto update_cache;
 301
 302         *rl = db_info.rl;
 303
 304 update_cache:
 305         cached_results[idx].tag = merged;
 306         cached_results[idx].rl = *rl;
 307         idx = (idx + 1) % ARRAY_SIZE(cached_results);
 308
 309         return !!*rl;
 310 }
 311
 312 static void clear_cache(struct symbol *sym)
 313 {
 314         memset(cached_results, 0, sizeof(cached_results));
 315 }
 316
 317 int get_mtag_rl(struct expression *expr, struct range_list **rl)
 318 {
 319         struct symbol *type;
 320         mtag_t tag;
 321         int offset;
 322
 323         if (is_local_variable(expr))
 324                 return 0;
 325         if (!expr_to_mtag_offset(expr, &tag, &offset))
 326                 return 0;
 327         if (offset >= MTAG_OFFSET_MASK)
 328                 return 0;
 329
 330         type = get_type(expr);
 331         if (invalid_type(type))
 332                 return 0;
 333
 334         return get_rl_from_mtag_offset(tag, offset, type, rl);
 335 }
 336
 337 void register_mtag_data(int id)
 338 {
 339         my_id = id;
 340
 341         ignored_mtag = str_to_mtag("extern boot_params");
 342         add_hook(&clear_cache, FUNC_DEF_HOOK);
 343
 344         if (!option_info)
 345                 return;
 346         add_hook(&match_global_assign, GLOBAL_ASSIGNMENT_HOOK);
 347         add_hook(&match_end_file, END_FILE_HOOK);
 348 }
 349