aboutsummaryrefslogtreecommitdiff
path: root/gold/script-sections.h
blob: 475e833459a7e34d8fee3b5d71a388880929e97c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
// script-sections.h -- linker script SECTIONS for gold   -*- C++ -*-

// Copyright (C) 2008-2023 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.

// This is for the support of the SECTIONS clause in linker scripts.

#ifndef GOLD_SCRIPT_SECTIONS_H
#define GOLD_SCRIPT_SECTIONS_H

#include <cstdio>
#include <list>
#include <vector>

namespace gold
{

struct Parser_output_section_header;
struct Parser_output_section_trailer;
struct Input_section_spec;
class Expression;
class Sections_element;
class Memory_region;
class Phdrs_element;
class Output_data;
class Output_section_definition;
class Output_section;
class Output_segment;
class Orphan_section_placement;

class Script_sections
{
 public:
  // This is a list, not a vector, because we insert orphan sections
  // in the middle.
  typedef std::list<Sections_element*> Sections_elements;

  // Logical script section types.  We map section types returned by the
  // parser into these since some section types have the same semantics.
  enum Section_type
  {
    // No section type specified.
    ST_NONE,
    // Section is NOLOAD.  We allocate space in the output but section
    // is not loaded in runtime.
    ST_NOLOAD,
    // No space is allocated to section.
    ST_NOALLOC
  };

  Script_sections();

  // Start a SECTIONS clause.
  void
  start_sections();

  // Finish a SECTIONS clause.
  void
  finish_sections();

  // Return whether we ever saw a SECTIONS clause.  If we did, then
  // all section layout needs to go through this class.
  bool
  saw_sections_clause() const
  { return this->saw_sections_clause_; }

  // Return whether we are currently processing a SECTIONS clause.
  bool
  in_sections_clause() const
  { return this->in_sections_clause_; }

  // Return whether we ever saw a PHDRS clause.  We ignore the PHDRS
  // clause unless we also saw a SECTIONS clause.
  bool
  saw_phdrs_clause() const
  { return this->saw_sections_clause_ && this->phdrs_elements_ != NULL; }

  // Start processing entries for an output section.
  void
  start_output_section(const char* name, size_t namelen,
		       const Parser_output_section_header*);

  // Finish processing entries for an output section.
  void
  finish_output_section(const Parser_output_section_trailer*);

  // Add a data item to the current output section.
  void
  add_data(int size, bool is_signed, Expression* val);

  // Add a symbol to be defined.
  void
  add_symbol_assignment(const char* name, size_t length, Expression* value,
			bool provide, bool hidden);

  // Add an assignment to the special dot symbol.
  void
  add_dot_assignment(Expression* value);

  // Add an assertion.
  void
  add_assertion(Expression* check, const char* message, size_t messagelen);

  // Add a setting for the fill value.
  void
  add_fill(Expression* val);

  // Add an input section specification.
  void
  add_input_section(const Input_section_spec* spec, bool keep);

  // Saw DATA_SEGMENT_ALIGN.
  void
  data_segment_align();

  // Saw DATA_SEGMENT_RELRO_END.
  void
  data_segment_relro_end();

  // Create any required sections.
  void
  create_sections(Layout*);

  // Add any symbols we are defining to the symbol table.
  void
  add_symbols_to_table(Symbol_table*);

  // Finalize symbol values and check assertions.
  void
  finalize_symbols(Symbol_table* symtab, const Layout* layout);

  // Find the name of the output section to use for an input file name
  // and section name.  This returns a name, and sets
  // *OUTPUT_SECTION_SLOT to point to the address where the actual
  // output section may be stored.
  // 1) If the input section should be discarded, this returns NULL
  //    and sets *OUTPUT_SECTION_SLOT to NULL.
  // 2) If the input section is mapped by the SECTIONS clause, this
  //    returns the name to use for the output section (in permanent
  //    storage), and sets *OUTPUT_SECTION_SLOT to point to where the
  //    output section should be stored.  **OUTPUT_SECTION_SLOT will be
  //    non-NULL if we have seen this output section already.
  // 3) If the input section is not mapped by the SECTIONS clause,
  //    this returns SECTION_NAME, and sets *OUTPUT_SECTION_SLOT to
  //    NULL.
  // PSCRIPT_SECTION_TYPE points to a location for returning the section
  // type specified in script.  This can be SCRIPT_SECTION_TYPE_NONE if
  // no type is specified.
  // *KEEP indicates whether the section should survive garbage collection.
  // MATCH_INPUT_SPEC indicates whether the section should be matched
  // with input section specs or simply against the output section name
  // (i.e., for linker-created sections like .dynamic).
  const char*
  output_section_name(const char* file_name, const char* section_name,
		      Output_section*** output_section_slot,
		      Section_type* pscript_section_type,
		      bool* keep, bool match_input_spec);

  // Place a marker for an orphan output section into the SECTIONS
  // clause.
  void
  place_orphan(Output_section* os);

  // Set the addresses of all the output sections.  Return the segment
  // which holds the file header and segment headers, if any.
  Output_segment*
  set_section_addresses(Symbol_table*, Layout*);

  // Add a program header definition.
  void
  add_phdr(const char* name, size_t namelen, unsigned int type,
	   bool filehdr, bool phdrs, bool is_flags_valid, unsigned int flags,
	   Expression* load_address);

  // Return the number of segments we expect to create based on the
  // SECTIONS clause.
  size_t
  expected_segment_count(const Layout*) const;

  // Add the file header and segment header to non-load segments as
  // specified by the PHDRS clause.
  void
  put_headers_in_phdrs(Output_data* file_header, Output_data* segment_headers);

  // Look for an output section by name and return the address, the
  // load address, the alignment, and the size.  This is used when an
  // expression refers to an output section which was not actually
  // created.  This returns true if the section was found, false
  // otherwise.
  bool
  get_output_section_info(const char* name, uint64_t* address,
                          uint64_t* load_address, uint64_t* addralign,
                          uint64_t* size) const;

  // Release all Output_segments.  This is used in relaxation.
  void
  release_segments();

  // Whether we ever saw a SEGMENT_START expression, the presence of which
  // changes the behaviour of -Ttext, -Tdata and -Tbss options.
  bool
  saw_segment_start_expression() const
  { return this->saw_segment_start_expression_; }

  // Set the flag which indicates whether we saw a SEGMENT_START expression.
  void
  set_saw_segment_start_expression(bool value)
  { this->saw_segment_start_expression_ = value; }

  // Add a memory region.
  void
  add_memory_region(const char*, size_t, unsigned int,
		    Expression*, Expression*);

  // Find a memory region's origin.
  Expression*
  find_memory_region_origin(const char*, size_t);

  // Find a memory region's length.
  Expression*
  find_memory_region_length(const char*, size_t);

  // Find a memory region by name.
  Memory_region*
  find_memory_region(const char*, size_t);

  // Find a memory region that should be used by a given output section.
  Memory_region*
  find_memory_region(Output_section_definition*, bool, bool,
		     Output_section_definition**);

  // Returns true if the provide block of memory is contained
  // within a memory region.
  bool
  block_in_region(Symbol_table*, Layout*, uint64_t, uint64_t) const;
    
  // Set the memory region of the section.
  void
  set_memory_region(Memory_region*, bool);

  // Print the contents to the FILE.  This is for debugging.
  void
  print(FILE*) const;

  // Used for orphan sections.
  typedef Sections_elements::iterator Elements_iterator;

 private:
  typedef std::vector<Memory_region*> Memory_regions;
  typedef std::vector<Phdrs_element*> Phdrs_elements;

  // Create segments.
  Output_segment*
  create_segments(Layout*, uint64_t);

  // Create PT_NOTE and PT_TLS segments.
  void
  create_note_and_tls_segments(Layout*, const std::vector<Output_section*>*);

  // Return whether the section is a BSS section.
  static bool
  is_bss_section(const Output_section*);

  // Return the total size of the headers.
  size_t
  total_header_size(Layout* layout) const;

  // Return the amount we have to subtract from the LMA to accommodate
  // headers of the given size.
  uint64_t
  header_size_adjustment(uint64_t lma, size_t sizeof_headers) const;

  // Create the segments from a PHDRS clause.
  Output_segment*
  create_segments_from_phdrs_clause(Layout* layout, uint64_t);

  // Attach sections to segments from a PHDRS clause.
  void
  attach_sections_using_phdrs_clause(Layout*);

  // Set addresses of segments from a PHDRS clause.
  Output_segment*
  set_phdrs_clause_addresses(Layout*, uint64_t);

  // True if we ever saw a SECTIONS clause.
  bool saw_sections_clause_;
  // True if we are currently processing a SECTIONS clause.
  bool in_sections_clause_;
  // The list of elements in the SECTIONS clause.
  Sections_elements* sections_elements_;
  // The current output section, if there is one.
  Output_section_definition* output_section_;
  // The list of memory regions in the MEMORY clause.
  Memory_regions* memory_regions_;
  // The list of program headers in the PHDRS clause.
  Phdrs_elements* phdrs_elements_;
  // Where to put orphan sections.
  Orphan_section_placement* orphan_section_placement_;
  // A pointer to the last Sections_element when we see
  // DATA_SEGMENT_ALIGN.
  Sections_elements::iterator data_segment_align_start_;
  // Whether we have seen DATA_SEGMENT_ALIGN.
  bool saw_data_segment_align_;
  // Whether we have seen DATA_SEGMENT_RELRO_END.
  bool saw_relro_end_;
  // Whether we have seen SEGMENT_START.
  bool saw_segment_start_expression_;
  // Whether we have created all necessary segments.
  bool segments_created_;
};

// Attributes for memory regions.
enum
{
  MEM_EXECUTABLE   = (1 << 0),
  MEM_WRITEABLE    = (1 << 1),
  MEM_READABLE     = (1 << 2),
  MEM_ALLOCATABLE  = (1 << 3),
  MEM_INITIALIZED  = (1 << 4),
  MEM_ATTR_MASK    = (1 << 5) - 1
};

} // End namespace gold.

#endif // !defined(GOLD_SCRIPT_SECTIONS_H