| 1 | // script.h -- handle linker scripts for gold -*- C++ -*- |
| 2 | |
| 3 | // Copyright 2006, 2007, 2008 Free Software Foundation, Inc. |
| 4 | // Written by Ian Lance Taylor <iant@google.com>. |
| 5 | |
| 6 | // This file is part of gold. |
| 7 | |
| 8 | // This program is free software; you can redistribute it and/or modify |
| 9 | // it under the terms of the GNU General Public License as published by |
| 10 | // the Free Software Foundation; either version 3 of the License, or |
| 11 | // (at your option) any later version. |
| 12 | |
| 13 | // This program is distributed in the hope that it will be useful, |
| 14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | // GNU General Public License for more details. |
| 17 | |
| 18 | // You should have received a copy of the GNU General Public License |
| 19 | // along with this program; if not, write to the Free Software |
| 20 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, |
| 21 | // MA 02110-1301, USA. |
| 22 | |
| 23 | // We implement a subset of the original GNU ld linker script language |
| 24 | // for compatibility. The goal is not to implement the entire |
| 25 | // language. It is merely to implement enough to handle common uses. |
| 26 | // In particular we need to handle /usr/lib/libc.so on a typical |
| 27 | // GNU/Linux system, and we want to handle linker scripts used by the |
| 28 | // Linux kernel build. |
| 29 | |
| 30 | #ifndef GOLD_SCRIPT_H |
| 31 | #define GOLD_SCRIPT_H |
| 32 | |
| 33 | #include <cstdio> |
| 34 | #include <string> |
| 35 | #include <vector> |
| 36 | |
| 37 | #include "script-sections.h" |
| 38 | |
| 39 | namespace gold |
| 40 | { |
| 41 | |
| 42 | class General_options; |
| 43 | class Command_line; |
| 44 | class Symbol_table; |
| 45 | class Layout; |
| 46 | class Mapfile; |
| 47 | class Input_argument; |
| 48 | class Input_objects; |
| 49 | class Input_group; |
| 50 | class Input_file; |
| 51 | class Output_segment; |
| 52 | class Task_token; |
| 53 | class Workqueue; |
| 54 | struct Version_dependency_list; |
| 55 | struct Version_expression_list; |
| 56 | struct Version_tree; |
| 57 | |
| 58 | // This class represents an expression in a linker script. |
| 59 | |
| 60 | class Expression |
| 61 | { |
| 62 | protected: |
| 63 | // These should only be created by child classes. |
| 64 | Expression() |
| 65 | { } |
| 66 | |
| 67 | public: |
| 68 | virtual ~Expression() |
| 69 | { } |
| 70 | |
| 71 | // Return the value of the expression which is not permitted to |
| 72 | // refer to the dot symbol. CHECK_ASSERTIONS is true if we should |
| 73 | // check whether assertions are true. |
| 74 | uint64_t |
| 75 | eval(const Symbol_table*, const Layout*, bool check_assertions); |
| 76 | |
| 77 | // Return the value of an expression which is permitted to refer to |
| 78 | // the dot symbol. DOT_VALUE is the absolute value of the dot |
| 79 | // symbol. DOT_SECTION is the section in which dot is defined; it |
| 80 | // should be NULL if the dot symbol has an absolute value (e.g., is |
| 81 | // defined in a SECTIONS clause outside of any output section |
| 82 | // definition). This sets *RESULT_SECTION to indicate where the |
| 83 | // value is defined. If the value is absolute *RESULT_SECTION will |
| 84 | // be NULL. Note that the returned value is still an absolute |
| 85 | // value; to get a section relative value the caller must subtract |
| 86 | // the section address. |
| 87 | uint64_t |
| 88 | eval_with_dot(const Symbol_table*, const Layout*, bool check_assertions, |
| 89 | uint64_t dot_value, Output_section* dot_section, |
| 90 | Output_section** result_section); |
| 91 | |
| 92 | // Return the value of an expression which may or may not be |
| 93 | // permitted to refer to the dot symbol, depending on |
| 94 | // is_dot_available. |
| 95 | uint64_t |
| 96 | eval_maybe_dot(const Symbol_table*, const Layout*, bool check_assertions, |
| 97 | bool is_dot_available, uint64_t dot_value, |
| 98 | Output_section* dot_section, |
| 99 | Output_section** result_section); |
| 100 | |
| 101 | // Print the expression to the FILE. This is for debugging. |
| 102 | virtual void |
| 103 | print(FILE*) const = 0; |
| 104 | |
| 105 | protected: |
| 106 | struct Expression_eval_info; |
| 107 | |
| 108 | public: |
| 109 | // Compute the value of the expression (implemented by child class). |
| 110 | // This is public rather than protected because it is called |
| 111 | // directly by children of Expression on other Expression objects. |
| 112 | virtual uint64_t |
| 113 | value(const Expression_eval_info*) = 0; |
| 114 | |
| 115 | private: |
| 116 | // May not be copied. |
| 117 | Expression(const Expression&); |
| 118 | Expression& operator=(const Expression&); |
| 119 | }; |
| 120 | |
| 121 | |
| 122 | // Version_script_info stores information parsed from the version |
| 123 | // script, either provided by --version-script or as part of a linker |
| 124 | // script. A single Version_script_info object per target is owned by |
| 125 | // Script_options. |
| 126 | |
| 127 | class Version_script_info |
| 128 | { |
| 129 | public: |
| 130 | ~Version_script_info(); |
| 131 | |
| 132 | // Clear everything. |
| 133 | void |
| 134 | clear(); |
| 135 | |
| 136 | // Return whether any version were defined in the version script. |
| 137 | bool |
| 138 | empty() const |
| 139 | { return this->version_trees_.empty(); } |
| 140 | |
| 141 | // If there is a version associated with SYMBOL, return true, and |
| 142 | // set *VERSION to the version. Otherwise, return false. |
| 143 | bool |
| 144 | get_symbol_version(const char* symbol, std::string* version) const |
| 145 | { return this->get_symbol_version_helper(symbol, true, version); } |
| 146 | |
| 147 | // Return whether this symbol matches the local: section of some |
| 148 | // version. |
| 149 | bool |
| 150 | symbol_is_local(const char* symbol) const |
| 151 | { return this->get_symbol_version_helper(symbol, false, NULL); } |
| 152 | |
| 153 | // Return the names of versions defined in the version script. |
| 154 | // Strings are allocated out of the stringpool given in the |
| 155 | // constructor. |
| 156 | std::vector<std::string> |
| 157 | get_versions() const; |
| 158 | |
| 159 | // Return the list of dependencies for this version. |
| 160 | std::vector<std::string> |
| 161 | get_dependencies(const char* version) const; |
| 162 | |
| 163 | // The following functions should only be used by the bison helper |
| 164 | // functions. They allocate new structs whose memory belongs to |
| 165 | // Version_script_info. The bison functions copy the information |
| 166 | // from the version script into these structs. |
| 167 | struct Version_dependency_list* |
| 168 | allocate_dependency_list(); |
| 169 | |
| 170 | struct Version_expression_list* |
| 171 | allocate_expression_list(); |
| 172 | |
| 173 | struct Version_tree* |
| 174 | allocate_version_tree(); |
| 175 | |
| 176 | // Print contents to the FILE. This is for debugging. |
| 177 | void |
| 178 | print(FILE*) const; |
| 179 | |
| 180 | private: |
| 181 | void |
| 182 | print_expression_list(FILE* f, const Version_expression_list*) const; |
| 183 | |
| 184 | bool get_symbol_version_helper(const char* symbol, |
| 185 | bool check_global, |
| 186 | std::string* pversion) const; |
| 187 | |
| 188 | std::vector<struct Version_dependency_list*> dependency_lists_; |
| 189 | std::vector<struct Version_expression_list*> expression_lists_; |
| 190 | std::vector<struct Version_tree*> version_trees_; |
| 191 | }; |
| 192 | |
| 193 | // This class manages assignments to symbols. These can appear in |
| 194 | // three different locations in scripts: outside of a SECTIONS clause, |
| 195 | // within a SECTIONS clause, and within an output section definition |
| 196 | // within a SECTIONS clause. This can also appear on the command line |
| 197 | // via the --defsym command line option. |
| 198 | |
| 199 | class Symbol_assignment |
| 200 | { |
| 201 | public: |
| 202 | Symbol_assignment(const char* name, size_t namelen, Expression* val, |
| 203 | bool provide, bool hidden) |
| 204 | : name_(name, namelen), val_(val), provide_(provide), hidden_(hidden), |
| 205 | sym_(NULL) |
| 206 | { } |
| 207 | |
| 208 | // Add the symbol to the symbol table. |
| 209 | void |
| 210 | add_to_table(Symbol_table*); |
| 211 | |
| 212 | // Finalize the symbol value. |
| 213 | void |
| 214 | finalize(Symbol_table*, const Layout*); |
| 215 | |
| 216 | // Finalize the symbol value when it can refer to the dot symbol. |
| 217 | void |
| 218 | finalize_with_dot(Symbol_table*, const Layout*, uint64_t dot_value, |
| 219 | Output_section* dot_section); |
| 220 | |
| 221 | // Set the symbol value, but only if the value is absolute. This is |
| 222 | // used while processing a SECTIONS clause. We assume that dot is |
| 223 | // an absolute value here. We do not check assertions. |
| 224 | void |
| 225 | set_if_absolute(Symbol_table*, const Layout*, bool is_dot_available, |
| 226 | uint64_t dot_value); |
| 227 | |
| 228 | // Print the assignment to the FILE. This is for debugging. |
| 229 | void |
| 230 | print(FILE*) const; |
| 231 | |
| 232 | private: |
| 233 | // Shared by finalize and finalize_with_dot. |
| 234 | void |
| 235 | finalize_maybe_dot(Symbol_table*, const Layout*, bool is_dot_available, |
| 236 | uint64_t dot_value, Output_section* dot_section); |
| 237 | |
| 238 | // Sized version of finalize. |
| 239 | template<int size> |
| 240 | void |
| 241 | sized_finalize(Symbol_table*, const Layout*, bool is_dot_available, |
| 242 | uint64_t dot_value, Output_section*); |
| 243 | |
| 244 | // Symbol name. |
| 245 | std::string name_; |
| 246 | // Expression to assign to symbol. |
| 247 | Expression* val_; |
| 248 | // Whether the assignment should be provided (only set if there is |
| 249 | // an undefined reference to the symbol. |
| 250 | bool provide_; |
| 251 | // Whether the assignment should be hidden. |
| 252 | bool hidden_; |
| 253 | // The entry in the symbol table. |
| 254 | Symbol* sym_; |
| 255 | }; |
| 256 | |
| 257 | // This class manages assertions in linker scripts. These can appear |
| 258 | // in all the places where a Symbol_assignment can appear. |
| 259 | |
| 260 | class Script_assertion |
| 261 | { |
| 262 | public: |
| 263 | Script_assertion(Expression* check, const char* message, |
| 264 | size_t messagelen) |
| 265 | : check_(check), message_(message, messagelen) |
| 266 | { } |
| 267 | |
| 268 | // Check the assertion. |
| 269 | void |
| 270 | check(const Symbol_table*, const Layout*); |
| 271 | |
| 272 | // Print the assertion to the FILE. This is for debugging. |
| 273 | void |
| 274 | print(FILE*) const; |
| 275 | |
| 276 | private: |
| 277 | // The expression to check. |
| 278 | Expression* check_; |
| 279 | // The message to issue if the expression fails. |
| 280 | std::string message_; |
| 281 | }; |
| 282 | |
| 283 | // We can read a linker script in two different contexts: when |
| 284 | // initially parsing the command line, and when we find an input file |
| 285 | // which is actually a linker script. Also some of the data which can |
| 286 | // be set by a linker script can also be set via command line options |
| 287 | // like -e and --defsym. This means that we have a type of data which |
| 288 | // can be set both during command line option parsing and while |
| 289 | // reading input files. We store that data in an instance of this |
| 290 | // object. We will keep pointers to that instance in both the |
| 291 | // Command_line and Layout objects. |
| 292 | |
| 293 | class Script_options |
| 294 | { |
| 295 | public: |
| 296 | Script_options(); |
| 297 | |
| 298 | // Add a symbol to be defined. |
| 299 | void |
| 300 | add_symbol_assignment(const char* name, size_t length, Expression* value, |
| 301 | bool provide, bool hidden); |
| 302 | |
| 303 | // Add an assertion. |
| 304 | void |
| 305 | add_assertion(Expression* check, const char* message, size_t messagelen); |
| 306 | |
| 307 | // Define a symbol from the command line. |
| 308 | bool |
| 309 | define_symbol(const char* definition); |
| 310 | |
| 311 | // Create sections required by any linker scripts. |
| 312 | void |
| 313 | create_script_sections(Layout*); |
| 314 | |
| 315 | // Add all symbol definitions to the symbol table. |
| 316 | void |
| 317 | add_symbols_to_table(Symbol_table*); |
| 318 | |
| 319 | // Finalize the symbol values. Also check assertions. |
| 320 | void |
| 321 | finalize_symbols(Symbol_table*, const Layout*); |
| 322 | |
| 323 | // Version information parsed from a version script. Everything |
| 324 | // else has a pointer to this object. |
| 325 | Version_script_info* |
| 326 | version_script_info() |
| 327 | { return &this->version_script_info_; } |
| 328 | |
| 329 | const Version_script_info* |
| 330 | version_script_info() const |
| 331 | { return &this->version_script_info_; } |
| 332 | |
| 333 | // A SECTIONS clause parsed from a linker script. Everything else |
| 334 | // has a pointer to this object. |
| 335 | Script_sections* |
| 336 | script_sections() |
| 337 | { return &this->script_sections_; } |
| 338 | |
| 339 | const Script_sections* |
| 340 | script_sections() const |
| 341 | { return &this->script_sections_; } |
| 342 | |
| 343 | // Whether we saw a SECTIONS clause. |
| 344 | bool |
| 345 | saw_sections_clause() const |
| 346 | { return this->script_sections_.saw_sections_clause(); } |
| 347 | |
| 348 | // Whether we saw a PHDRS clause. |
| 349 | bool |
| 350 | saw_phdrs_clause() const |
| 351 | { return this->script_sections_.saw_phdrs_clause(); } |
| 352 | |
| 353 | // Set section addresses using a SECTIONS clause. Return the |
| 354 | // segment which should hold the file header and segment headers; |
| 355 | // this may return NULL, in which case the headers are not in a |
| 356 | // loadable segment. |
| 357 | Output_segment* |
| 358 | set_section_addresses(Symbol_table*, Layout*); |
| 359 | |
| 360 | // Print the script to the FILE. This is for debugging. |
| 361 | void |
| 362 | print(FILE*) const; |
| 363 | |
| 364 | private: |
| 365 | // We keep a list of symbol assignments which occur outside of a |
| 366 | // SECTIONS clause. |
| 367 | typedef std::vector<Symbol_assignment*> Symbol_assignments; |
| 368 | |
| 369 | // We keep a list of all assertions whcih occur outside of a |
| 370 | // SECTIONS clause. |
| 371 | typedef std::vector<Script_assertion*> Assertions; |
| 372 | |
| 373 | // The entry address. This will be empty if not set. |
| 374 | std::string entry_; |
| 375 | // Symbols to set. |
| 376 | Symbol_assignments symbol_assignments_; |
| 377 | // Assertions to check. |
| 378 | Assertions assertions_; |
| 379 | // Version information parsed from a version script. |
| 380 | Version_script_info version_script_info_; |
| 381 | // Information from any SECTIONS clauses. |
| 382 | Script_sections script_sections_; |
| 383 | }; |
| 384 | |
| 385 | // FILE was found as an argument on the command line, but was not |
| 386 | // recognized as an ELF file. Try to read it as a script. Return |
| 387 | // true if the file was handled. This has to handle /usr/lib/libc.so |
| 388 | // on a GNU/Linux system. *USED_NEXT_BLOCKER is set to indicate |
| 389 | // whether the function took over NEXT_BLOCKER. |
| 390 | |
| 391 | bool |
| 392 | read_input_script(Workqueue*, const General_options&, Symbol_table*, Layout*, |
| 393 | Dirsearch*, Input_objects*, Mapfile*, Input_group*, |
| 394 | const Input_argument*, Input_file*, |
| 395 | Task_token* next_blocker, bool* used_next_blocker); |
| 396 | |
| 397 | // FILE was found as an argument to --script (-T). |
| 398 | // Read it as a script, and execute its contents immediately. |
| 399 | |
| 400 | bool |
| 401 | read_commandline_script(const char* filename, Command_line* cmdline); |
| 402 | |
| 403 | // FILE was found as an argument to --version-script. Read it as a |
| 404 | // version script, and store its contents in |
| 405 | // cmdline->script_options()->version_script_info(). |
| 406 | |
| 407 | bool |
| 408 | read_version_script(const char* filename, Command_line* cmdline); |
| 409 | |
| 410 | // FILENAME was found as an argument to --dynamic-list. Read it as a |
| 411 | // version script (actually, a versym_node from a version script), and |
| 412 | // store its contents in DYNAMIC_LIST. |
| 413 | |
| 414 | bool |
| 415 | read_dynamic_list(const char* filename, Command_line* cmdline, |
| 416 | Script_options* dynamic_list); |
| 417 | |
| 418 | } // End namespace gold. |
| 419 | |
| 420 | #endif // !defined(GOLD_SCRIPT_H) |