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dbe717ef ILT |
1 | // script.h -- handle linker scripts for gold -*- C++ -*- |
2 | ||
e5756efb | 3 | // Copyright 2006, 2007, 2008 Free Software Foundation, Inc. |
6cb15b7f ILT |
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 | ||
dbe717ef ILT |
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 | ||
494e05f4 | 33 | #include <cstdio> |
04bf7072 | 34 | #include <string> |
e5756efb ILT |
35 | #include <vector> |
36 | ||
494e05f4 | 37 | #include "script-sections.h" |
09124467 | 38 | |
dbe717ef ILT |
39 | namespace gold |
40 | { | |
41 | ||
42 | class General_options; | |
3c2fafa5 | 43 | class Command_line; |
dbe717ef ILT |
44 | class Symbol_table; |
45 | class Layout; | |
7d9e3d98 | 46 | class Mapfile; |
3c2fafa5 | 47 | class Input_argument; |
dbe717ef ILT |
48 | class Input_objects; |
49 | class Input_group; | |
50 | class Input_file; | |
a445fddf | 51 | class Output_segment; |
dbe717ef | 52 | class Task_token; |
3c2fafa5 | 53 | class Workqueue; |
494e05f4 ILT |
54 | struct Version_dependency_list; |
55 | struct Version_expression_list; | |
56 | struct Version_tree; | |
dbe717ef | 57 | |
e5756efb ILT |
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 | ||
a445fddf | 71 | // Return the value of the expression which is not permitted to |
919ed24c ILT |
72 | // refer to the dot symbol. CHECK_ASSERTIONS is true if we should |
73 | // check whether assertions are true. | |
e5756efb | 74 | uint64_t |
919ed24c | 75 | eval(const Symbol_table*, const Layout*, bool check_assertions); |
e5756efb | 76 | |
a445fddf | 77 | // Return the value of an expression which is permitted to refer to |
77e65537 ILT |
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. | |
a445fddf | 87 | uint64_t |
919ed24c ILT |
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); | |
a445fddf ILT |
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 | |
919ed24c ILT |
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, | |
77e65537 | 99 | Output_section** result_section); |
a445fddf | 100 | |
494e05f4 ILT |
101 | // Print the expression to the FILE. This is for debugging. |
102 | virtual void | |
103 | print(FILE*) const = 0; | |
104 | ||
e5756efb ILT |
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 | ||
09124467 ILT |
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 | ||
494e05f4 ILT |
127 | class Version_script_info |
128 | { | |
09124467 ILT |
129 | public: |
130 | ~Version_script_info(); | |
131 | ||
1ef1f3d3 ILT |
132 | // Clear everything. |
133 | void | |
134 | clear(); | |
135 | ||
09124467 ILT |
136 | // Return whether any version were defined in the version script. |
137 | bool | |
138 | empty() const | |
139 | { return this->version_trees_.empty(); } | |
140 | ||
141 | // Return the version associated with the given symbol name. | |
142 | // Strings are allocated out of the stringpool given in the | |
143 | // constructor. Strings are allocated out of the stringpool given | |
144 | // in the constructor. | |
145 | const std::string& | |
146 | get_symbol_version(const char* symbol) const | |
147 | { return get_symbol_version_helper(symbol, true); } | |
148 | ||
149 | // Return whether this symbol matches the local: section of a | |
1dd940af | 150 | // version script (it doesn't matter which). |
09124467 ILT |
151 | bool |
152 | symbol_is_local(const char* symbol) const | |
1dd940af ILT |
153 | { |
154 | return (get_symbol_version(symbol).empty() | |
155 | && !get_symbol_version_helper(symbol, false).empty()); | |
156 | } | |
09124467 ILT |
157 | |
158 | // Return the names of versions defined in the version script. | |
159 | // Strings are allocated out of the stringpool given in the | |
160 | // constructor. | |
161 | std::vector<std::string> | |
162 | get_versions() const; | |
163 | ||
164 | // Return the list of dependencies for this version. | |
165 | std::vector<std::string> | |
166 | get_dependencies(const char* version) const; | |
167 | ||
168 | // The following functions should only be used by the bison helper | |
169 | // functions. They allocate new structs whose memory belongs to | |
170 | // Version_script_info. The bison functions copy the information | |
171 | // from the version script into these structs. | |
172 | struct Version_dependency_list* | |
173 | allocate_dependency_list(); | |
174 | ||
175 | struct Version_expression_list* | |
176 | allocate_expression_list(); | |
177 | ||
178 | struct Version_tree* | |
179 | allocate_version_tree(); | |
180 | ||
494e05f4 ILT |
181 | // Print contents to the FILE. This is for debugging. |
182 | void | |
183 | print(FILE*) const; | |
184 | ||
09124467 | 185 | private: |
494e05f4 ILT |
186 | void |
187 | print_expression_list(FILE* f, const Version_expression_list*) const; | |
188 | ||
09124467 ILT |
189 | const std::string& get_symbol_version_helper(const char* symbol, |
190 | bool check_global) const; | |
191 | ||
192 | std::vector<struct Version_dependency_list*> dependency_lists_; | |
193 | std::vector<struct Version_expression_list*> expression_lists_; | |
194 | std::vector<struct Version_tree*> version_trees_; | |
195 | }; | |
196 | ||
494e05f4 ILT |
197 | // This class manages assignments to symbols. These can appear in |
198 | // three different locations in scripts: outside of a SECTIONS clause, | |
199 | // within a SECTIONS clause, and within an output section definition | |
200 | // within a SECTIONS clause. This can also appear on the command line | |
201 | // via the --defsym command line option. | |
202 | ||
203 | class Symbol_assignment | |
204 | { | |
205 | public: | |
206 | Symbol_assignment(const char* name, size_t namelen, Expression* val, | |
207 | bool provide, bool hidden) | |
208 | : name_(name, namelen), val_(val), provide_(provide), hidden_(hidden), | |
209 | sym_(NULL) | |
210 | { } | |
211 | ||
212 | // Add the symbol to the symbol table. | |
213 | void | |
9b07f471 | 214 | add_to_table(Symbol_table*); |
494e05f4 ILT |
215 | |
216 | // Finalize the symbol value. | |
a445fddf ILT |
217 | void |
218 | finalize(Symbol_table*, const Layout*); | |
219 | ||
220 | // Finalize the symbol value when it can refer to the dot symbol. | |
221 | void | |
77e65537 ILT |
222 | finalize_with_dot(Symbol_table*, const Layout*, uint64_t dot_value, |
223 | Output_section* dot_section); | |
a445fddf ILT |
224 | |
225 | // Set the symbol value, but only if the value is absolute. This is | |
77e65537 | 226 | // used while processing a SECTIONS clause. We assume that dot is |
919ed24c | 227 | // an absolute value here. We do not check assertions. |
a445fddf ILT |
228 | void |
229 | set_if_absolute(Symbol_table*, const Layout*, bool is_dot_available, | |
77e65537 | 230 | uint64_t dot_value); |
494e05f4 ILT |
231 | |
232 | // Print the assignment to the FILE. This is for debugging. | |
233 | void | |
234 | print(FILE*) const; | |
235 | ||
236 | private: | |
a445fddf ILT |
237 | // Shared by finalize and finalize_with_dot. |
238 | void | |
239 | finalize_maybe_dot(Symbol_table*, const Layout*, bool is_dot_available, | |
77e65537 | 240 | uint64_t dot_value, Output_section* dot_section); |
a445fddf | 241 | |
494e05f4 ILT |
242 | // Sized version of finalize. |
243 | template<int size> | |
244 | void | |
a445fddf | 245 | sized_finalize(Symbol_table*, const Layout*, bool is_dot_available, |
77e65537 | 246 | uint64_t dot_value, Output_section*); |
494e05f4 ILT |
247 | |
248 | // Symbol name. | |
249 | std::string name_; | |
250 | // Expression to assign to symbol. | |
251 | Expression* val_; | |
252 | // Whether the assignment should be provided (only set if there is | |
253 | // an undefined reference to the symbol. | |
254 | bool provide_; | |
255 | // Whether the assignment should be hidden. | |
256 | bool hidden_; | |
257 | // The entry in the symbol table. | |
258 | Symbol* sym_; | |
259 | }; | |
260 | ||
261 | // This class manages assertions in linker scripts. These can appear | |
262 | // in all the places where a Symbol_assignment can appear. | |
263 | ||
264 | class Script_assertion | |
265 | { | |
266 | public: | |
267 | Script_assertion(Expression* check, const char* message, | |
268 | size_t messagelen) | |
269 | : check_(check), message_(message, messagelen) | |
270 | { } | |
271 | ||
272 | // Check the assertion. | |
273 | void | |
274 | check(const Symbol_table*, const Layout*); | |
275 | ||
276 | // Print the assertion to the FILE. This is for debugging. | |
277 | void | |
278 | print(FILE*) const; | |
279 | ||
280 | private: | |
281 | // The expression to check. | |
282 | Expression* check_; | |
283 | // The message to issue if the expression fails. | |
284 | std::string message_; | |
285 | }; | |
286 | ||
e5756efb ILT |
287 | // We can read a linker script in two different contexts: when |
288 | // initially parsing the command line, and when we find an input file | |
289 | // which is actually a linker script. Also some of the data which can | |
290 | // be set by a linker script can also be set via command line options | |
291 | // like -e and --defsym. This means that we have a type of data which | |
292 | // can be set both during command line option parsing and while | |
293 | // reading input files. We store that data in an instance of this | |
294 | // object. We will keep pointers to that instance in both the | |
295 | // Command_line and Layout objects. | |
296 | ||
297 | class Script_options | |
298 | { | |
299 | public: | |
300 | Script_options(); | |
301 | ||
494e05f4 | 302 | // Add a symbol to be defined. |
e5756efb ILT |
303 | void |
304 | add_symbol_assignment(const char* name, size_t length, Expression* value, | |
494e05f4 ILT |
305 | bool provide, bool hidden); |
306 | ||
307 | // Add an assertion. | |
308 | void | |
309 | add_assertion(Expression* check, const char* message, size_t messagelen); | |
e5756efb ILT |
310 | |
311 | // Define a symbol from the command line. | |
312 | bool | |
313 | define_symbol(const char* definition); | |
314 | ||
919ed24c ILT |
315 | // Create sections required by any linker scripts. |
316 | void | |
317 | create_script_sections(Layout*); | |
318 | ||
e5756efb ILT |
319 | // Add all symbol definitions to the symbol table. |
320 | void | |
9b07f471 | 321 | add_symbols_to_table(Symbol_table*); |
e5756efb | 322 | |
a445fddf | 323 | // Finalize the symbol values. Also check assertions. |
e5756efb ILT |
324 | void |
325 | finalize_symbols(Symbol_table*, const Layout*); | |
326 | ||
09124467 ILT |
327 | // Version information parsed from a version script. Everything |
328 | // else has a pointer to this object. | |
329 | Version_script_info* | |
330 | version_script_info() | |
494e05f4 | 331 | { return &this->version_script_info_; } |
09124467 | 332 | |
a5dc0706 ILT |
333 | const Version_script_info* |
334 | version_script_info() const | |
335 | { return &this->version_script_info_; } | |
336 | ||
494e05f4 ILT |
337 | // A SECTIONS clause parsed from a linker script. Everything else |
338 | // has a pointer to this object. | |
339 | Script_sections* | |
340 | script_sections() | |
341 | { return &this->script_sections_; } | |
e5756efb | 342 | |
8f2eb564 ILT |
343 | const Script_sections* |
344 | script_sections() const | |
345 | { return &this->script_sections_; } | |
346 | ||
a445fddf ILT |
347 | // Whether we saw a SECTIONS clause. |
348 | bool | |
349 | saw_sections_clause() const | |
350 | { return this->script_sections_.saw_sections_clause(); } | |
351 | ||
1c4f3631 ILT |
352 | // Whether we saw a PHDRS clause. |
353 | bool | |
354 | saw_phdrs_clause() const | |
355 | { return this->script_sections_.saw_phdrs_clause(); } | |
356 | ||
a445fddf ILT |
357 | // Set section addresses using a SECTIONS clause. Return the |
358 | // segment which should hold the file header and segment headers; | |
359 | // this may return NULL, in which case the headers are not in a | |
360 | // loadable segment. | |
361 | Output_segment* | |
362 | set_section_addresses(Symbol_table*, Layout*); | |
363 | ||
494e05f4 | 364 | // Print the script to the FILE. This is for debugging. |
e5756efb | 365 | void |
494e05f4 ILT |
366 | print(FILE*) const; |
367 | ||
368 | private: | |
369 | // We keep a list of symbol assignments which occur outside of a | |
370 | // SECTIONS clause. | |
371 | typedef std::vector<Symbol_assignment*> Symbol_assignments; | |
372 | ||
373 | // We keep a list of all assertions whcih occur outside of a | |
374 | // SECTIONS clause. | |
375 | typedef std::vector<Script_assertion*> Assertions; | |
e5756efb ILT |
376 | |
377 | // The entry address. This will be empty if not set. | |
378 | std::string entry_; | |
379 | // Symbols to set. | |
380 | Symbol_assignments symbol_assignments_; | |
494e05f4 ILT |
381 | // Assertions to check. |
382 | Assertions assertions_; | |
09124467 ILT |
383 | // Version information parsed from a version script. |
384 | Version_script_info version_script_info_; | |
494e05f4 ILT |
385 | // Information from any SECTIONS clauses. |
386 | Script_sections script_sections_; | |
e5756efb ILT |
387 | }; |
388 | ||
dbe717ef | 389 | // FILE was found as an argument on the command line, but was not |
da769d56 ILT |
390 | // recognized as an ELF file. Try to read it as a script. Return |
391 | // true if the file was handled. This has to handle /usr/lib/libc.so | |
392 | // on a GNU/Linux system. *USED_NEXT_BLOCKER is set to indicate | |
393 | // whether the function took over NEXT_BLOCKER. | |
dbe717ef ILT |
394 | |
395 | bool | |
396 | read_input_script(Workqueue*, const General_options&, Symbol_table*, Layout*, | |
7d9e3d98 | 397 | Dirsearch*, Input_objects*, Mapfile*, Input_group*, |
da769d56 ILT |
398 | const Input_argument*, Input_file*, |
399 | Task_token* next_blocker, bool* used_next_blocker); | |
dbe717ef | 400 | |
3c2fafa5 ILT |
401 | // FILE was found as an argument to --script (-T). |
402 | // Read it as a script, and execute its contents immediately. | |
403 | ||
404 | bool | |
405 | read_commandline_script(const char* filename, Command_line*); | |
406 | ||
09124467 ILT |
407 | // FILE was found as an argument to --version-script. Read it as a |
408 | // version script, and store its contents in | |
409 | // cmdline->script_options()->version_script_info(). | |
410 | ||
411 | bool | |
412 | read_version_script(const char* filename, Command_line* cmdline); | |
413 | ||
414 | ||
dbe717ef ILT |
415 | } // End namespace gold. |
416 | ||
417 | #endif // !defined(GOLD_SCRIPT_H) |