gold/script-sections.h

   1 // script-sections.h -- linker script SECTIONS for gold   -*- C++ -*-
   2
   3 // Copyright 2008, 2009 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 // This is for the support of the SECTIONS clause in linker scripts.
  24
  25 #ifndef GOLD_SCRIPT_SECTIONS_H
  26 #define GOLD_SCRIPT_SECTIONS_H
  27
  28 #include <cstdio>
  29 #include <list>
  30 #include <vector>
  31
  32 namespace gold
  33 {
  34
  35 struct Parser_output_section_header;
  36 struct Parser_output_section_trailer;
  37 struct Input_section_spec;
  38 class Expression;
  39 class Sections_element;
  40 class Phdrs_element;
  41 class Output_data;
  42 class Output_section_definition;
  43 class Output_section;
  44 class Output_segment;
  45 class Orphan_section_placement;
  46
  47 class Script_sections
  48 {
  49  private:
  50   // This is a list, not a vector, because we insert orphan sections
  51   // in the middle.
  52   typedef std::list<Sections_element*> Sections_elements;
  53
  54  public:
  55
  56   // Logical script section types.  We map section types returned by the
  57   // parser into these since some section types have the same semantics.
  58   enum Section_type
  59   {
  60     // No section type specified.
  61     ST_NONE,
  62     // Section is NOLOAD.  We allocate space in the output but section
  63     // is not loaded in runtime.
  64     ST_NOLOAD,
  65     // No space is allocated to section.
  66     ST_NOALLOC
  67   };
  68
  69   Script_sections();
  70
  71   // Start a SECTIONS clause.
  72   void
  73   start_sections();
  74
  75   // Finish a SECTIONS clause.
  76   void
  77   finish_sections();
  78
  79   // Return whether we ever saw a SECTIONS clause.  If we did, then
  80   // all section layout needs to go through this class.
  81   bool
  82   saw_sections_clause() const
  83   { return this->saw_sections_clause_; }
  84
  85   // Return whether we are currently processing a SECTIONS clause.
  86   bool
  87   in_sections_clause() const
  88   { return this->in_sections_clause_; }
  89
  90   // Return whether we ever saw a PHDRS clause.  We ignore the PHDRS
  91   // clause unless we also saw a SECTIONS clause.
  92   bool
  93   saw_phdrs_clause() const
  94   { return this->saw_sections_clause_ && this->phdrs_elements_ != NULL; }
  95
  96   // Start processing entries for an output section.
  97   void
  98   start_output_section(const char* name, size_t namelen,
  99                        const Parser_output_section_header*);
 100
 101   // Finish processing entries for an output section.
 102   void
 103   finish_output_section(const Parser_output_section_trailer*);
 104
 105   // Add a data item to the current output section.
 106   void
 107   add_data(int size, bool is_signed, Expression* val);
 108
 109   // Add a symbol to be defined.
 110   void
 111   add_symbol_assignment(const char* name, size_t length, Expression* value,
 112                         bool provide, bool hidden);
 113
 114   // Add an assignment to the special dot symbol.
 115   void
 116   add_dot_assignment(Expression* value);
 117
 118   // Add an assertion.
 119   void
 120   add_assertion(Expression* check, const char* message, size_t messagelen);
 121
 122   // Add a setting for the fill value.
 123   void
 124   add_fill(Expression* val);
 125
 126   // Add an input section specification.
 127   void
 128   add_input_section(const Input_section_spec* spec, bool keep);
 129
 130   // Saw DATA_SEGMENT_ALIGN.
 131   void
 132   data_segment_align();
 133
 134   // Saw DATA_SEGMENT_RELRO_END.
 135   void
 136   data_segment_relro_end();
 137
 138   // Create any required sections.
 139   void
 140   create_sections(Layout*);
 141
 142   // Add any symbols we are defining to the symbol table.
 143   void
 144   add_symbols_to_table(Symbol_table*);
 145
 146   // Finalize symbol values and check assertions.
 147   void
 148   finalize_symbols(Symbol_table* symtab, const Layout* layout);
 149
 150   // Find the name of the output section to use for an input file name
 151   // and section name.  This returns a name, and sets
 152   // *OUTPUT_SECTION_SLOT to point to the address where the actual
 153   // output section may be stored.
 154   // 1) If the input section should be discarded, this returns NULL
 155   //    and sets *OUTPUT_SECTION_SLOT to NULL.
 156   // 2) If the input section is mapped by the SECTIONS clause, this
 157   //    returns the name to use for the output section (in permanent
 158   //    storage), and sets *OUTPUT_SECTION_SLOT to point to where the
 159   //    output section should be stored.  **OUTPUT_SECTION_SLOT will be
 160   //    non-NULL if we have seen this output section already.
 161   // 3) If the input section is not mapped by the SECTIONS clause,
 162   //    this returns SECTION_NAME, and sets *OUTPUT_SECTION_SLOT to
 163   //    NULL.
 164   // PSCRIPT_SECTION_TYPE points to a location for returning the section
 165   // type specified in script.  This can be SCRIPT_SECTION_TYPE_NONE if
 166   // no type is specified.
 167   const char*
 168   output_section_name(const char* file_name, const char* section_name,
 169                       Output_section*** output_section_slot,
 170                       Section_type* pscript_section_type);
 171
 172   // Place a marker for an orphan output section into the SECTIONS
 173   // clause.
 174   void
 175   place_orphan(Output_section* os);
 176
 177   // Set the addresses of all the output sections.  Return the segment
 178   // which holds the file header and segment headers, if any.
 179   Output_segment*
 180   set_section_addresses(Symbol_table*, Layout*);
 181
 182   // Add a program header definition.
 183   void
 184   add_phdr(const char* name, size_t namelen, unsigned int type,
 185            bool filehdr, bool phdrs, bool is_flags_valid, unsigned int flags,
 186            Expression* load_address);
 187
 188   // Return the number of segments we expect to create based on the
 189   // SECTIONS clause.
 190   size_t
 191   expected_segment_count(const Layout*) const;
 192
 193   // Add the file header and segment header to non-load segments as
 194   // specified by the PHDRS clause.
 195   void
 196   put_headers_in_phdrs(Output_data* file_header, Output_data* segment_headers);
 197
 198   // Look for an output section by name and return the address, the
 199   // load address, the alignment, and the size.  This is used when an
 200   // expression refers to an output section which was not actually
 201   // created.  This returns true if the section was found, false
 202   // otherwise.
 203   bool
 204   get_output_section_info(const char* name, uint64_t* address,
 205                           uint64_t* load_address, uint64_t* addralign,
 206                           uint64_t* size) const;
 207
 208   // Release all Output_segments.  This is used in relaxation.
 209   void
 210   release_segments();
 211
 212   // Whether we ever saw a SEGMENT_START expression, the presence of which
 213   // changes the behaviour of -Ttext, -Tdata and -Tbss options.
 214   bool
 215   saw_segment_start_expression() const
 216   { return this->saw_segment_start_expression_; }
 217
 218   // Set the flag which indicates whether we saw a SEGMENT_START expression.
 219   void
 220   set_saw_segment_start_expression(bool value)
 221   { this->saw_segment_start_expression_ = value; }
 222
 223   // Print the contents to the FILE.  This is for debugging.
 224   void
 225   print(FILE*) const;
 226
 227   // Used for orphan sections.
 228   typedef Sections_elements::iterator Elements_iterator;
 229
 230  private:
 231   typedef std::vector<Phdrs_element*> Phdrs_elements;
 232
 233   // Create segments.
 234   Output_segment*
 235   create_segments(Layout*);
 236
 237   // Create PT_NOTE and PT_TLS segments.
 238   void
 239   create_note_and_tls_segments(Layout*, const std::vector<Output_section*>*);
 240
 241   // Return whether the section is a BSS section.
 242   static bool
 243   is_bss_section(const Output_section*);
 244
 245   // Return the total size of the headers.
 246   size_t
 247   total_header_size(Layout* layout) const;
 248
 249   // Return the amount we have to subtract from the LMA to accomodate
 250   // headers of the given size.
 251   uint64_t
 252   header_size_adjustment(uint64_t lma, size_t sizeof_headers) const;
 253
 254   // Create the segments from a PHDRS clause.
 255   Output_segment*
 256   create_segments_from_phdrs_clause(Layout* layout);
 257
 258   // Attach sections to segments from a PHDRS clause.
 259   void
 260   attach_sections_using_phdrs_clause(Layout*);
 261
 262   // Set addresses of segments from a PHDRS clause.
 263   Output_segment*
 264   set_phdrs_clause_addresses(Layout*);
 265
 266   // True if we ever saw a SECTIONS clause.
 267   bool saw_sections_clause_;
 268   // True if we are currently processing a SECTIONS clause.
 269   bool in_sections_clause_;
 270   // The list of elements in the SECTIONS clause.
 271   Sections_elements* sections_elements_;
 272   // The current output section, if there is one.
 273   Output_section_definition* output_section_;
 274   // The list of program headers in the PHDRS clause.
 275   Phdrs_elements* phdrs_elements_;
 276   // Where to put orphan sections.
 277   Orphan_section_placement* orphan_section_placement_;
 278   // A pointer to the last Sections_element when we see
 279   // DATA_SEGMENT_ALIGN.
 280   Sections_elements::iterator data_segment_align_start_;
 281   // Whether we have seen DATA_SEGMENT_ALIGN.
 282   bool saw_data_segment_align_;
 283   // Whether we have seen DATA_SEGMENT_RELRO_END.
 284   bool saw_relro_end_;
 285   // Whether we have seen SEGMENT_START.
 286   bool saw_segment_start_expression_;
 287 };
 288
 289 } // End namespace gold.
 290
 291 #endif // !defined(GOLD_SCRIPT_SECTIONS_H