Subversion Repositories openrisc_2011-10-31

// script.h -- handle linker scripts for gold   -*- C++ -*-

// Copyright 2006, 2007, 2008 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.

// We implement a subset of the original GNU ld linker script language

// for compatibility.  The goal is not to implement the entire

// language.  It is merely to implement enough to handle common uses.

// In particular we need to handle /usr/lib/libc.so on a typical

// GNU/Linux system, and we want to handle linker scripts used by the

// Linux kernel build.

#ifndef GOLD_SCRIPT_H

#define GOLD_SCRIPT_H

#include <cstdio>

#include <string>

#include <vector>

#include "script-sections.h"

namespace gold

{

class General_options;

class Command_line;

class Symbol_table;

class Layout;

class Mapfile;

class Input_argument;

class Input_arguments;

class Input_objects;

class Input_group;

class Input_file;

class Output_segment;

class Task_token;

class Workqueue;

struct Version_dependency_list;

struct Version_expression_list;

struct Version_tree;

// This class represents an expression in a linker script.

class Expression

{

 protected:

  // These should only be created by child classes.

  Expression()

  { }

 public:

  virtual ~Expression()

  { }

  // Return the value of the expression which is not permitted to

  // refer to the dot symbol.  CHECK_ASSERTIONS is true if we should

  // check whether assertions are true.

  uint64_t

  eval(const Symbol_table*, const Layout*, bool check_assertions);

  // Return the value of an expression which is permitted to refer to

  // the dot symbol.  DOT_VALUE is the absolute value of the dot

  // symbol.  DOT_SECTION is the section in which dot is defined; it

  // should be NULL if the dot symbol has an absolute value (e.g., is

  // defined in a SECTIONS clause outside of any output section

  // definition).  This sets *RESULT_SECTION to indicate where the

  // value is defined.  If the value is absolute *RESULT_SECTION will

  // be NULL.  Note that the returned value is still an absolute

  // value; to get a section relative value the caller must subtract

  // the section address.

  uint64_t

  eval_with_dot(const Symbol_table*, const Layout*, bool check_assertions,

                uint64_t dot_value, Output_section* dot_section,

                Output_section** result_section);

  // Return the value of an expression which may or may not be

  // permitted to refer to the dot symbol, depending on

  // is_dot_available.

  uint64_t

  eval_maybe_dot(const Symbol_table*, const Layout*, bool check_assertions,

                 bool is_dot_available, uint64_t dot_value,

                 Output_section* dot_section,

                 Output_section** result_section);

  // Print the expression to the FILE.  This is for debugging.

  virtual void

  print(FILE*) const = 0;

 protected:

  struct Expression_eval_info;

 public:

  // Compute the value of the expression (implemented by child class).

  // This is public rather than protected because it is called

  // directly by children of Expression on other Expression objects.

  virtual uint64_t

  value(const Expression_eval_info*) = 0;

 private:

  // May not be copied.

  Expression(const Expression&);

  Expression& operator=(const Expression&);

};

// Version_script_info stores information parsed from the version

// script, either provided by --version-script or as part of a linker

// script.  A single Version_script_info object per target is owned by

// Script_options.

class Version_script_info

{

 public:

  ~Version_script_info();

  // Clear everything.

  void

  clear();

  // Return whether any version were defined in the version script.

  bool

  empty() const

  { return this->version_trees_.empty(); }

  // If there is a version associated with SYMBOL, return true, and

  // set *VERSION to the version.  Otherwise, return false.

  bool

  get_symbol_version(const char* symbol, std::string* version) const

  { return this->get_symbol_version_helper(symbol, true, version); }

  // Return whether this symbol matches the local: section of some

  // version.

  bool

  symbol_is_local(const char* symbol) const

  { return this->get_symbol_version_helper(symbol, false, NULL); }

  // Return the names of versions defined in the version script.

  // Strings are allocated out of the stringpool given in the

  // constructor.

  std::vector<std::string>

  get_versions() const;

  // Return the list of dependencies for this version.

  std::vector<std::string>

  get_dependencies(const char* version) const;

  // The following functions should only be used by the bison helper

  // functions.  They allocate new structs whose memory belongs to

  // Version_script_info.  The bison functions copy the information

  // from the version script into these structs.

  struct Version_dependency_list*

  allocate_dependency_list();

  struct Version_expression_list*

  allocate_expression_list();

  struct Version_tree*

  allocate_version_tree();

  // Print contents to the FILE.  This is for debugging.

  void

  print(FILE*) const;

 private:

  void

  print_expression_list(FILE* f, const Version_expression_list*) const;

  bool get_symbol_version_helper(const char* symbol,

                                 bool check_global,

                                 std::string* pversion) const;

  std::vector<struct Version_dependency_list*> dependency_lists_;

  std::vector<struct Version_expression_list*> expression_lists_;

  std::vector<struct Version_tree*> version_trees_;

};

// This class manages assignments to symbols.  These can appear in

// three different locations in scripts: outside of a SECTIONS clause,

// within a SECTIONS clause, and within an output section definition

// within a SECTIONS clause.  This can also appear on the command line

// via the --defsym command line option.

class Symbol_assignment

{

 public:

  Symbol_assignment(const char* name, size_t namelen, Expression* val,

                    bool provide, bool hidden)

    : name_(name, namelen), val_(val), provide_(provide), hidden_(hidden),

      sym_(NULL)

  { }

  // Add the symbol to the symbol table.

  void

  add_to_table(Symbol_table*);

  // Finalize the symbol value.

  void

  finalize(Symbol_table*, const Layout*);

  // Finalize the symbol value when it can refer to the dot symbol.

  void

  finalize_with_dot(Symbol_table*, const Layout*, uint64_t dot_value,

                    Output_section* dot_section);

  // Set the symbol value, but only if the value is absolute.  This is

  // used while processing a SECTIONS clause.  We assume that dot is

  // an absolute value here.  We do not check assertions.

  void

  set_if_absolute(Symbol_table*, const Layout*, bool is_dot_available,

                  uint64_t dot_value);

  // Print the assignment to the FILE.  This is for debugging.

  void

  print(FILE*) const;

 private:

  // Shared by finalize and finalize_with_dot.

  void

  finalize_maybe_dot(Symbol_table*, const Layout*, bool is_dot_available,

                     uint64_t dot_value, Output_section* dot_section);

  // Sized version of finalize.

  template<int size>

  void

  sized_finalize(Symbol_table*, const Layout*, bool is_dot_available,

                 uint64_t dot_value, Output_section*);

  // Symbol name.

  std::string name_;

  // Expression to assign to symbol.

  Expression* val_;

  // Whether the assignment should be provided (only set if there is

  // an undefined reference to the symbol.

  bool provide_;

  // Whether the assignment should be hidden.

  bool hidden_;

  // The entry in the symbol table.

  Symbol* sym_;

};

// This class manages assertions in linker scripts.  These can appear

// in all the places where a Symbol_assignment can appear.

class Script_assertion

{

 public:

  Script_assertion(Expression* check, const char* message,

                   size_t messagelen)

    : check_(check), message_(message, messagelen)

  { }

  // Check the assertion.

  void

  check(const Symbol_table*, const Layout*);

  // Print the assertion to the FILE.  This is for debugging.

  void

  print(FILE*) const;

 private:

  // The expression to check.

  Expression* check_;

  // The message to issue if the expression fails.

  std::string message_;

};

// We can read a linker script in two different contexts: when

// initially parsing the command line, and when we find an input file

// which is actually a linker script.  Also some of the data which can

// be set by a linker script can also be set via command line options

// like -e and --defsym.  This means that we have a type of data which

// can be set both during command line option parsing and while

// reading input files.  We store that data in an instance of this

// object.  We will keep pointers to that instance in both the

// Command_line and Layout objects.

class Script_options

{

 public:

  Script_options();

  // Add a symbol to be defined.

  void

  add_symbol_assignment(const char* name, size_t length, Expression* value,

                        bool provide, bool hidden);

  // Add an assertion.

  void

  add_assertion(Expression* check, const char* message, size_t messagelen);

  // Define a symbol from the command line.

  bool

  define_symbol(const char* definition);

  // Create sections required by any linker scripts.

  void

  create_script_sections(Layout*);

  // Add all symbol definitions to the symbol table.

  void

  add_symbols_to_table(Symbol_table*);

  // Finalize the symbol values.  Also check assertions.

  void

  finalize_symbols(Symbol_table*, const Layout*);

  // Version information parsed from a version script.  Everything

  // else has a pointer to this object.

  Version_script_info*

  version_script_info()

  { return &this->version_script_info_; }

  const Version_script_info*

  version_script_info() const

  { return &this->version_script_info_; }

  // A SECTIONS clause parsed from a linker script.  Everything else

  // has a pointer to this object.

  Script_sections*

  script_sections()

  { return &this->script_sections_; }

  const Script_sections*

  script_sections() const

  { return &this->script_sections_; }

  // Whether we saw a SECTIONS clause.

  bool

  saw_sections_clause() const

  { return this->script_sections_.saw_sections_clause(); }

  // Whether we saw a PHDRS clause.

  bool

  saw_phdrs_clause() const

  { return this->script_sections_.saw_phdrs_clause(); }

  // Set section addresses using a SECTIONS clause.  Return the

  // segment which should hold the file header and segment headers;

  // this may return NULL, in which case the headers are not in a

  // loadable segment.

  Output_segment*

  set_section_addresses(Symbol_table*, Layout*);

  // Print the script to the FILE.  This is for debugging.

  void

  print(FILE*) const;

 private:

  // We keep a list of symbol assignments which occur outside of a

  // SECTIONS clause.

  typedef std::vector<Symbol_assignment*> Symbol_assignments;

  // We keep a list of all assertions whcih occur outside of a

  // SECTIONS clause.

  typedef std::vector<Script_assertion*> Assertions;

  // The entry address.  This will be empty if not set.

  std::string entry_;

  // Symbols to set.

  Symbol_assignments symbol_assignments_;

  // Assertions to check.

  Assertions assertions_;

  // Version information parsed from a version script.

  Version_script_info version_script_info_;

  // Information from any SECTIONS clauses.

  Script_sections script_sections_;

};

// Information about a script input that will persist during the whole linker

// run. Needed only during an incremental build to retrieve the input files

// added by this script.

class Script_info

{

 public:

  Script_info(Input_arguments* inputs)

    : inputs_(inputs)

  { }

  // Returns the input files included because of this script.

  Input_arguments*

  inputs()

  { return this->inputs_; }

 private:

  Input_arguments* inputs_;

};

// FILE was found as an argument on the command line, but was not

// recognized as an ELF file.  Try to read it as a script.  Return

// true if the file was handled.  This has to handle /usr/lib/libc.so

// on a GNU/Linux system.  *USED_NEXT_BLOCKER is set to indicate

// whether the function took over NEXT_BLOCKER.

bool

read_input_script(Workqueue*, Symbol_table*, Layout*, Dirsearch*, int,

                  Input_objects*, Mapfile*, Input_group*,

                  const Input_argument*, Input_file*,

                  Task_token* next_blocker, bool* used_next_blocker);

// FILE was found as an argument to --script (-T).

// Read it as a script, and execute its contents immediately.

bool

read_commandline_script(const char* filename, Command_line* cmdline);

// FILE was found as an argument to --version-script.  Read it as a

// version script, and store its contents in

// cmdline->script_options()->version_script_info().

bool

read_version_script(const char* filename, Command_line* cmdline);

// FILENAME was found as an argument to --dynamic-list.  Read it as a

// version script (actually, a versym_node from a version script), and

// store its contents in DYNAMIC_LIST.

bool

read_dynamic_list(const char* filename, Command_line* cmdline,

                  Script_options* dynamic_list);

} // End namespace gold.

#endif // !defined(GOLD_SCRIPT_H)