--- /dev/null
+// target.h -- target support for gold -*- C++ -*-
+
+// Copyright 2006, 2007, 2008, 2009 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.
+
+// The abstract class Target is the interface for target specific
+// support. It defines abstract methods which each target must
+// implement. Typically there will be one target per processor, but
+// in some cases it may be necessary to have subclasses.
+
+// For speed and consistency we want to use inline functions to handle
+// relocation processing. So besides implementations of the abstract
+// methods, each target is expected to define a template
+// specialization of the relocation functions.
+
+#ifndef GOLD_TARGET_H
+#define GOLD_TARGET_H
+
+#include "elfcpp.h"
+#include "options.h"
+#include "parameters.h"
+#include "debug.h"
+
+namespace gold
+{
+
+class General_options;
+class Object;
+class Relobj;
+template<int size, bool big_endian>
+class Sized_relobj;
+class Relocatable_relocs;
+template<int size, bool big_endian>
+class Relocate_info;
+class Reloc_symbol_changes;
+class Symbol;
+template<int size>
+class Sized_symbol;
+class Symbol_table;
+class Output_section;
+
+// The abstract class for target specific handling.
+
+class Target
+{
+ public:
+ virtual ~Target()
+ { }
+
+ // Return the bit size that this target implements. This should
+ // return 32 or 64.
+ int
+ get_size() const
+ { return this->pti_->size; }
+
+ // Return whether this target is big-endian.
+ bool
+ is_big_endian() const
+ { return this->pti_->is_big_endian; }
+
+ // Machine code to store in e_machine field of ELF header.
+ elfcpp::EM
+ machine_code() const
+ { return this->pti_->machine_code; }
+
+ // Whether this target has a specific make_symbol function.
+ bool
+ has_make_symbol() const
+ { return this->pti_->has_make_symbol; }
+
+ // Whether this target has a specific resolve function.
+ bool
+ has_resolve() const
+ { return this->pti_->has_resolve; }
+
+ // Whether this target has a specific code fill function.
+ bool
+ has_code_fill() const
+ { return this->pti_->has_code_fill; }
+
+ // Return the default name of the dynamic linker.
+ const char*
+ dynamic_linker() const
+ { return this->pti_->dynamic_linker; }
+
+ // Return the default address to use for the text segment.
+ uint64_t
+ default_text_segment_address() const
+ { return this->pti_->default_text_segment_address; }
+
+ // Return the ABI specified page size.
+ uint64_t
+ abi_pagesize() const
+ {
+ if (parameters->options().max_page_size() > 0)
+ return parameters->options().max_page_size();
+ else
+ return this->pti_->abi_pagesize;
+ }
+
+ // Return the common page size used on actual systems.
+ uint64_t
+ common_pagesize() const
+ {
+ if (parameters->options().common_page_size() > 0)
+ return std::min(parameters->options().common_page_size(),
+ this->abi_pagesize());
+ else
+ return std::min(this->pti_->common_pagesize,
+ this->abi_pagesize());
+ }
+
+ // If we see some object files with .note.GNU-stack sections, and
+ // some objects files without them, this returns whether we should
+ // consider the object files without them to imply that the stack
+ // should be executable.
+ bool
+ is_default_stack_executable() const
+ { return this->pti_->is_default_stack_executable; }
+
+ // Return a character which may appear as a prefix for a wrap
+ // symbol. If this character appears, we strip it when checking for
+ // wrapping and add it back when forming the final symbol name.
+ // This should be '\0' if not special prefix is required, which is
+ // the normal case.
+ char
+ wrap_char() const
+ { return this->pti_->wrap_char; }
+
+ // Return the special section index which indicates a small common
+ // symbol. This will return SHN_UNDEF if there are no small common
+ // symbols.
+ elfcpp::Elf_Half
+ small_common_shndx() const
+ { return this->pti_->small_common_shndx; }
+
+ // Return values to add to the section flags for the section holding
+ // small common symbols.
+ elfcpp::Elf_Xword
+ small_common_section_flags() const
+ {
+ gold_assert(this->pti_->small_common_shndx != elfcpp::SHN_UNDEF);
+ return this->pti_->small_common_section_flags;
+ }
+
+ // Return the special section index which indicates a large common
+ // symbol. This will return SHN_UNDEF if there are no large common
+ // symbols.
+ elfcpp::Elf_Half
+ large_common_shndx() const
+ { return this->pti_->large_common_shndx; }
+
+ // Return values to add to the section flags for the section holding
+ // large common symbols.
+ elfcpp::Elf_Xword
+ large_common_section_flags() const
+ {
+ gold_assert(this->pti_->large_common_shndx != elfcpp::SHN_UNDEF);
+ return this->pti_->large_common_section_flags;
+ }
+
+ // This hook is called when an output section is created.
+ void
+ new_output_section(Output_section* os) const
+ { this->do_new_output_section(os); }
+
+ // This is called to tell the target to complete any sections it is
+ // handling. After this all sections must have their final size.
+ void
+ finalize_sections(Layout* layout)
+ { return this->do_finalize_sections(layout); }
+
+ // Return the value to use for a global symbol which needs a special
+ // value in the dynamic symbol table. This will only be called if
+ // the backend first calls symbol->set_needs_dynsym_value().
+ uint64_t
+ dynsym_value(const Symbol* sym) const
+ { return this->do_dynsym_value(sym); }
+
+ // Return a string to use to fill out a code section. This is
+ // basically one or more NOPS which must fill out the specified
+ // length in bytes.
+ std::string
+ code_fill(section_size_type length) const
+ { return this->do_code_fill(length); }
+
+ // Return whether SYM is known to be defined by the ABI. This is
+ // used to avoid inappropriate warnings about undefined symbols.
+ bool
+ is_defined_by_abi(const Symbol* sym) const
+ { return this->do_is_defined_by_abi(sym); }
+
+ // Adjust the output file header before it is written out. VIEW
+ // points to the header in external form. LEN is the length.
+ void
+ adjust_elf_header(unsigned char* view, int len) const
+ { return this->do_adjust_elf_header(view, len); }
+
+ // Return whether NAME is a local label name. This is used to implement the
+ // --discard-locals options.
+ bool
+ is_local_label_name(const char* name) const
+ { return this->do_is_local_label_name(name); }
+
+ // A function starts at OFFSET in section SHNDX in OBJECT. That
+ // function was compiled with -fsplit-stack, but it refers to a
+ // function which was compiled without -fsplit-stack. VIEW is a
+ // modifiable view of the section; VIEW_SIZE is the size of the
+ // view. The target has to adjust the function so that it allocates
+ // enough stack.
+ void
+ calls_non_split(Relobj* object, unsigned int shndx,
+ section_offset_type fnoffset, section_size_type fnsize,
+ unsigned char* view, section_size_type view_size,
+ std::string* from, std::string* to) const
+ {
+ this->do_calls_non_split(object, shndx, fnoffset, fnsize, view, view_size,
+ from, to);
+ }
+
+ // Make an ELF object.
+ template<int size, bool big_endian>
+ Object*
+ make_elf_object(const std::string& name, Input_file* input_file,
+ off_t offset, const elfcpp::Ehdr<size, big_endian>& ehdr)
+ { return this->do_make_elf_object(name, input_file, offset, ehdr); }
+
+ // Make an output section.
+ Output_section*
+ make_output_section(const char* name, elfcpp::Elf_Word type,
+ elfcpp::Elf_Xword flags)
+ { return this->do_make_output_section(name, type, flags); }
+
+ // Return true if target wants to perform relaxation.
+ bool
+ may_relax() const
+ {
+ // Run the dummy relaxation pass twice if relaxation debugging is enabled.
+ if (is_debugging_enabled(DEBUG_RELAXATION))
+ return true;
+
+ return this->do_may_relax();
+ }
+
+ // Perform a relaxation pass. Return true if layout may be changed.
+ bool
+ relax(int pass, const Input_objects* input_objects, Symbol_table* symtab,
+ Layout* layout)
+ {
+ // Run the dummy relaxation pass twice if relaxation debugging is enabled.
+ if (is_debugging_enabled(DEBUG_RELAXATION))
+ return pass < 2;
+
+ return this->do_relax(pass, input_objects, symtab, layout);
+ }
+
+ protected:
+ // This struct holds the constant information for a child class. We
+ // use a struct to avoid the overhead of virtual function calls for
+ // simple information.
+ struct Target_info
+ {
+ // Address size (32 or 64).
+ int size;
+ // Whether the target is big endian.
+ bool is_big_endian;
+ // The code to store in the e_machine field of the ELF header.
+ elfcpp::EM machine_code;
+ // Whether this target has a specific make_symbol function.
+ bool has_make_symbol;
+ // Whether this target has a specific resolve function.
+ bool has_resolve;
+ // Whether this target has a specific code fill function.
+ bool has_code_fill;
+ // Whether an object file with no .note.GNU-stack sections implies
+ // that the stack should be executable.
+ bool is_default_stack_executable;
+ // Prefix character to strip when checking for wrapping.
+ char wrap_char;
+ // The default dynamic linker name.
+ const char* dynamic_linker;
+ // The default text segment address.
+ uint64_t default_text_segment_address;
+ // The ABI specified page size.
+ uint64_t abi_pagesize;
+ // The common page size used by actual implementations.
+ uint64_t common_pagesize;
+ // The special section index for small common symbols; SHN_UNDEF
+ // if none.
+ elfcpp::Elf_Half small_common_shndx;
+ // The special section index for large common symbols; SHN_UNDEF
+ // if none.
+ elfcpp::Elf_Half large_common_shndx;
+ // Section flags for small common section.
+ elfcpp::Elf_Xword small_common_section_flags;
+ // Section flags for large common section.
+ elfcpp::Elf_Xword large_common_section_flags;
+ };
+
+ Target(const Target_info* pti)
+ : pti_(pti)
+ { }
+
+ // Virtual function which may be implemented by the child class.
+ virtual void
+ do_new_output_section(Output_section*) const
+ { }
+
+ // Virtual function which may be implemented by the child class.
+ virtual void
+ do_finalize_sections(Layout*)
+ { }
+
+ // Virtual function which may be implemented by the child class.
+ virtual uint64_t
+ do_dynsym_value(const Symbol*) const
+ { gold_unreachable(); }
+
+ // Virtual function which must be implemented by the child class if
+ // needed.
+ virtual std::string
+ do_code_fill(section_size_type) const
+ { gold_unreachable(); }
+
+ // Virtual function which may be implemented by the child class.
+ virtual bool
+ do_is_defined_by_abi(const Symbol*) const
+ { return false; }
+
+ // Adjust the output file header before it is written out. VIEW
+ // points to the header in external form. LEN is the length, and
+ // will be one of the values of elfcpp::Elf_sizes<size>::ehdr_size.
+ // By default, we do nothing.
+ virtual void
+ do_adjust_elf_header(unsigned char*, int) const
+ { }
+
+ // Virtual function which may be overriden by the child class.
+ virtual bool
+ do_is_local_label_name(const char*) const;
+
+ // Virtual function which may be overridden by the child class.
+ virtual void
+ do_calls_non_split(Relobj* object, unsigned int, section_offset_type,
+ section_size_type, unsigned char*, section_size_type,
+ std::string*, std::string*) const;
+
+ // make_elf_object hooks. There are four versions of these for
+ // different address sizes and endianities.
+
+#ifdef HAVE_TARGET_32_LITTLE
+ // Virtual functions which may be overriden by the child class.
+ virtual Object*
+ do_make_elf_object(const std::string&, Input_file*, off_t,
+ const elfcpp::Ehdr<32, false>&);
+#endif
+
+#ifdef HAVE_TARGET_32_BIG
+ // Virtual functions which may be overriden by the child class.
+ virtual Object*
+ do_make_elf_object(const std::string&, Input_file*, off_t,
+ const elfcpp::Ehdr<32, true>&);
+#endif
+
+#ifdef HAVE_TARGET_64_LITTLE
+ // Virtual functions which may be overriden by the child class.
+ virtual Object*
+ do_make_elf_object(const std::string&, Input_file*, off_t,
+ const elfcpp::Ehdr<64, false>& ehdr);
+#endif
+
+#ifdef HAVE_TARGET_64_BIG
+ // Virtual functions which may be overriden by the child class.
+ virtual Object*
+ do_make_elf_object(const std::string& name, Input_file* input_file,
+ off_t offset, const elfcpp::Ehdr<64, true>& ehdr);
+#endif
+
+ // Virtual functions which may be overriden by the child class.
+ virtual Output_section*
+ do_make_output_section(const char* name, elfcpp::Elf_Word type,
+ elfcpp::Elf_Xword flags);
+
+ // Virtual function which may be overriden by the child class.
+ virtual bool
+ do_may_relax() const
+ { return parameters->options().relax(); }
+
+ // Virtual function which may be overriden by the child class.
+ virtual bool
+ do_relax(int, const Input_objects*, Symbol_table*, Layout*)
+ { return false; }
+
+ // A function for targets to call. Return whether BYTES/LEN matches
+ // VIEW/VIEW_SIZE at OFFSET.
+ bool
+ match_view(const unsigned char* view, section_size_type view_size,
+ section_offset_type offset, const char* bytes, size_t len) const;
+
+ // Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET
+ // for LEN bytes.
+ void
+ set_view_to_nop(unsigned char* view, section_size_type view_size,
+ section_offset_type offset, size_t len) const;
+
+ private:
+ // The implementations of the four do_make_elf_object virtual functions are
+ // almost identical except for their sizes and endianity. We use a template.
+ // for their implementations.
+ template<int size, bool big_endian>
+ inline Object*
+ do_make_elf_object_implementation(const std::string&, Input_file*, off_t,
+ const elfcpp::Ehdr<size, big_endian>&);
+
+ Target(const Target&);
+ Target& operator=(const Target&);
+
+ // The target information.
+ const Target_info* pti_;
+};
+
+// The abstract class for a specific size and endianness of target.
+// Each actual target implementation class should derive from an
+// instantiation of Sized_target.
+
+template<int size, bool big_endian>
+class Sized_target : public Target
+{
+ public:
+ // Make a new symbol table entry for the target. This should be
+ // overridden by a target which needs additional information in the
+ // symbol table. This will only be called if has_make_symbol()
+ // returns true.
+ virtual Sized_symbol<size>*
+ make_symbol() const
+ { gold_unreachable(); }
+
+ // Resolve a symbol for the target. This should be overridden by a
+ // target which needs to take special action. TO is the
+ // pre-existing symbol. SYM is the new symbol, seen in OBJECT.
+ // VERSION is the version of SYM. This will only be called if
+ // has_resolve() returns true.
+ virtual void
+ resolve(Symbol*, const elfcpp::Sym<size, big_endian>&, Object*,
+ const char*)
+ { gold_unreachable(); }
+
+ // Process the relocs for a section, and record information of the
+ // mapping from source to destination sections. This mapping is later
+ // used to determine unreferenced garbage sections. This procedure is
+ // only called during garbage collection.
+ virtual void
+ gc_process_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Sized_relobj<size, big_endian>* object,
+ unsigned int data_shndx,
+ unsigned int sh_type,
+ const unsigned char* prelocs,
+ size_t reloc_count,
+ Output_section* output_section,
+ bool needs_special_offset_handling,
+ size_t local_symbol_count,
+ const unsigned char* plocal_symbols) = 0;
+
+ // Scan the relocs for a section, and record any information
+ // required for the symbol. OPTIONS is the command line options.
+ // SYMTAB is the symbol table. OBJECT is the object in which the
+ // section appears. DATA_SHNDX is the section index that these
+ // relocs apply to. SH_TYPE is the type of the relocation section,
+ // SHT_REL or SHT_RELA. PRELOCS points to the relocation data.
+ // RELOC_COUNT is the number of relocs. LOCAL_SYMBOL_COUNT is the
+ // number of local symbols. OUTPUT_SECTION is the output section.
+ // NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets to the output
+ // sections are not mapped as usual. PLOCAL_SYMBOLS points to the
+ // local symbol data from OBJECT. GLOBAL_SYMBOLS is the array of
+ // pointers to the global symbol table from OBJECT.
+ virtual void
+ scan_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Sized_relobj<size, big_endian>* object,
+ unsigned int data_shndx,
+ unsigned int sh_type,
+ const unsigned char* prelocs,
+ size_t reloc_count,
+ Output_section* output_section,
+ bool needs_special_offset_handling,
+ size_t local_symbol_count,
+ const unsigned char* plocal_symbols) = 0;
+
+ // Relocate section data. SH_TYPE is the type of the relocation
+ // section, SHT_REL or SHT_RELA. PRELOCS points to the relocation
+ // information. RELOC_COUNT is the number of relocs.
+ // OUTPUT_SECTION is the output section.
+ // NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets must be mapped
+ // to correspond to the output section. VIEW is a view into the
+ // output file holding the section contents, VIEW_ADDRESS is the
+ // virtual address of the view, and VIEW_SIZE is the size of the
+ // view. If NEEDS_SPECIAL_OFFSET_HANDLING is true, the VIEW_xx
+ // parameters refer to the complete output section data, not just
+ // the input section data.
+ virtual void
+ relocate_section(const Relocate_info<size, big_endian>*,
+ unsigned int sh_type,
+ const unsigned char* prelocs,
+ size_t reloc_count,
+ Output_section* output_section,
+ bool needs_special_offset_handling,
+ unsigned char* view,
+ typename elfcpp::Elf_types<size>::Elf_Addr view_address,
+ section_size_type view_size,
+ const Reloc_symbol_changes*) = 0;
+
+ // Scan the relocs during a relocatable link. The parameters are
+ // like scan_relocs, with an additional Relocatable_relocs
+ // parameter, used to record the disposition of the relocs.
+ virtual void
+ scan_relocatable_relocs(const General_options& options,
+ Symbol_table* symtab,
+ Layout* layout,
+ Sized_relobj<size, big_endian>* object,
+ unsigned int data_shndx,
+ unsigned int sh_type,
+ const unsigned char* prelocs,
+ size_t reloc_count,
+ Output_section* output_section,
+ bool needs_special_offset_handling,
+ size_t local_symbol_count,
+ const unsigned char* plocal_symbols,
+ Relocatable_relocs*) = 0;
+
+ // Relocate a section during a relocatable link. The parameters are
+ // like relocate_section, with additional parameters for the view of
+ // the output reloc section.
+ virtual void
+ relocate_for_relocatable(const Relocate_info<size, big_endian>*,
+ unsigned int sh_type,
+ const unsigned char* prelocs,
+ size_t reloc_count,
+ Output_section* output_section,
+ off_t offset_in_output_section,
+ const Relocatable_relocs*,
+ unsigned char* view,
+ typename elfcpp::Elf_types<size>::Elf_Addr
+ view_address,
+ section_size_type view_size,
+ unsigned char* reloc_view,
+ section_size_type reloc_view_size) = 0;
+
+ protected:
+ Sized_target(const Target::Target_info* pti)
+ : Target(pti)
+ {
+ gold_assert(pti->size == size);
+ gold_assert(pti->is_big_endian ? big_endian : !big_endian);
+ }
+};
+
+} // End namespace gold.
+
+#endif // !defined(GOLD_TARGET_H)
projects / msp430-binutils.git / blobdiff