gold/script-sections.h

   1 // script-sections.h -- linker script SECTIONS for gold   -*- C++ -*-
   2
   3 // Copyright 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 // 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 <vector>
  30
  31 namespace gold
  32 {
  33
  34 struct Parser_output_section_header;
  35 struct Parser_output_section_trailer;
  36 struct Input_section_spec;
  37 class Expression;
  38 class Sections_element;
  39 class Phdrs_element;
  40 class Output_data;
  41 class Output_section_definition;
  42 class Output_section;
  43 class Output_segment;
  44
  45 class Script_sections
  46 {
  47  public:
  48   Script_sections();
  49
  50   // Start a SECTIONS clause.
  51   void
  52   start_sections();
  53
  54   // Finish a SECTIONS clause.
  55   void
  56   finish_sections();
  57
  58   // Return whether we ever saw a SECTIONS clause.  If we did, then
  59   // all section layout needs to go through this class.
  60   bool
  61   saw_sections_clause() const
  62   { return this->saw_sections_clause_; }
  63
  64   // Return whether we are currently processing a SECTIONS clause.
  65   bool
  66   in_sections_clause() const
  67   { return this->in_sections_clause_; }
  68
  69   // Return whether we ever saw a PHDRS clause.  We ignore the PHDRS
  70   // clause unless we also saw a SECTIONS clause.
  71   bool
  72   saw_phdrs_clause() const
  73   { return this->saw_sections_clause_ && this->phdrs_elements_ != NULL; }
  74
  75   // Start processing entries for an output section.
  76   void
  77   start_output_section(const char* name, size_t namelen,
  78                        const Parser_output_section_header*);
  79
  80   // Finish processing entries for an output section.
  81   void
  82   finish_output_section(const Parser_output_section_trailer*);
  83
  84   // Add a data item to the current output section.
  85   void
  86   add_data(int size, bool is_signed, Expression* val);
  87
  88   // Add a symbol to be defined.
  89   void
  90   add_symbol_assignment(const char* name, size_t length, Expression* value,
  91                         bool provide, bool hidden);
  92
  93   // Add an assignment to the special dot symbol.
  94   void
  95   add_dot_assignment(Expression* value);
  96
  97   // Add an assertion.
  98   void
  99   add_assertion(Expression* check, const char* message, size_t messagelen);
 100
 101   // Add a setting for the fill value.
 102   void
 103   add_fill(Expression* val);
 104
 105   // Add an input section specification.
 106   void
 107   add_input_section(const Input_section_spec* spec, bool keep);
 108
 109   // Saw DATA_SEGMENT_ALIGN.
 110   void
 111   data_segment_align();
 112
 113   // Saw DATA_SEGMENT_RELRO_END.
 114   void
 115   data_segment_relro_end();
 116
 117   // Create any required sections.
 118   void
 119   create_sections(Layout*);
 120
 121   // Add any symbols we are defining to the symbol table.
 122   void
 123   add_symbols_to_table(Symbol_table*);
 124
 125   // Finalize symbol values and check assertions.
 126   void
 127   finalize_symbols(Symbol_table* symtab, const Layout* layout);
 128
 129   // Find the name of the output section to use for an input file name
 130   // and section name.  This returns a name, and sets
 131   // *OUTPUT_SECTION_SLOT to point to the address where the actual
 132   // output section may be stored.
 133   // 1) If the input section should be discarded, this returns NULL
 134   //    and sets *OUTPUT_SECTION_SLOT to NULL.
 135   // 2) If the input section is mapped by the SECTIONS clause, this
 136   //    returns the name to use for the output section (in permanent
 137   //    storage), and sets *OUTPUT_SECTION_SLOT to point to where the
 138   //    output section should be stored.  **OUTPUT_SECTION_SLOT will be
 139   //    non-NULL if we have seen this output section already.
 140   // 3) If the input section is not mapped by the SECTIONS clause,
 141   //    this returns SECTION_NAME, and sets *OUTPUT_SECTION_SLOT to
 142   //    NULL.
 143   const char*
 144   output_section_name(const char* file_name, const char* section_name,
 145                       Output_section*** output_section_slot);
 146
 147   // Place a marker for an orphan output section into the SECTIONS
 148   // clause.
 149   void
 150   place_orphan(Output_section* os);
 151
 152   // Set the addresses of all the output sections.  Return the segment
 153   // which holds the file header and segment headers, if any.
 154   Output_segment*
 155   set_section_addresses(Symbol_table*, Layout*);
 156
 157   // Add a program header definition.
 158   void
 159   add_phdr(const char* name, size_t namelen, unsigned int type,
 160            bool filehdr, bool phdrs, bool is_flags_valid, unsigned int flags,
 161            Expression* load_address);
 162
 163   // Return the number of segments we expect to create based on the
 164   // SECTIONS clause.
 165   size_t
 166   expected_segment_count(const Layout*) const;
 167
 168   // Add the file header and segment header to non-load segments as
 169   // specified by the PHDRS clause.
 170   void
 171   put_headers_in_phdrs(Output_data* file_header, Output_data* segment_headers);
 172
 173   // Look for an output section by name and return the address, the
 174   // load address, the alignment, and the size.  This is used when an
 175   // expression refers to an output section which was not actually
 176   // created.  This returns true if the section was found, false
 177   // otherwise.
 178   bool
 179   get_output_section_info(const char* name, uint64_t* address,
 180                           uint64_t* load_address, uint64_t* addralign,
 181                           uint64_t* size) const;
 182
 183   // Print the contents to the FILE.  This is for debugging.
 184   void
 185   print(FILE*) const;
 186
 187  private:
 188   typedef std::vector<Sections_element*> Sections_elements;
 189
 190   typedef std::vector<Phdrs_element*> Phdrs_elements;
 191
 192   // Create segments.
 193   Output_segment*
 194   create_segments(Layout*);
 195
 196   // Create PT_NOTE and PT_TLS segments.
 197   void
 198   create_note_and_tls_segments(Layout*, const std::vector<Output_section*>*);
 199
 200   // Return whether the section is a BSS section.
 201   static bool
 202   is_bss_section(const Output_section*);
 203
 204   // Return the total size of the headers.
 205   size_t
 206   total_header_size(Layout* layout) const;
 207
 208   // Return the amount we have to subtract from the LMA to accomodate
 209   // headers of the given size.
 210   uint64_t
 211   header_size_adjustment(uint64_t lma, size_t sizeof_headers) const;
 212
 213   // Create the segments from a PHDRS clause.
 214   Output_segment*
 215   create_segments_from_phdrs_clause(Layout* layout);
 216
 217   // Attach sections to segments from a PHDRS clause.
 218   void
 219   attach_sections_using_phdrs_clause(Layout*);
 220
 221   // Set addresses of segments from a PHDRS clause.
 222   Output_segment*
 223   set_phdrs_clause_addresses(Layout*);
 224
 225   // True if we ever saw a SECTIONS clause.
 226   bool saw_sections_clause_;
 227   // True if we are currently processing a SECTIONS clause.
 228   bool in_sections_clause_;
 229   // The list of elements in the SECTIONS clause.
 230   Sections_elements* sections_elements_;
 231   // The current output section, if there is one.
 232   Output_section_definition* output_section_;
 233   // The list of program headers in the PHDRS clause.
 234   Phdrs_elements* phdrs_elements_;
 235   // The index of the next Sections_element when we see
 236   // DATA_SEGMENT_ALIGN.
 237   size_t data_segment_align_index_;
 238   // Whether we have seen DATA_SEGMENT_RELRO_END.
 239   bool saw_relro_end_;
 240 };
 241
 242 } // End namespace gold.
 243
 244 #endif // !defined(GOLD_SCRIPT_SECTIONS_H