// target.h -- target support for gold -*- C++ -*-
-// Copyright 2006, 2007 Free Software Foundation, Inc.
+// Copyright 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
#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_data;
class Output_section;
+class Input_objects;
+class Task;
// The abstract class for target specific handling.
virtual ~Target()
{ }
+ // Virtual function which is set to return true by a target if
+ // it can use relocation types to determine if a function's
+ // pointer is taken.
+ virtual bool
+ can_check_for_function_pointers() const
+ { return false; }
+
+ // This function is used in ICF (icf.cc). This is set to true by
+ // the target if a relocation to a merged section can be processed
+ // to retrieve the contents of the merged section.
+ virtual bool
+ can_icf_inline_merge_sections () const
+ { return false; }
+
+ // Whether a section called SECTION_NAME may have function pointers to
+ // sections not eligible for safe ICF folding.
+ virtual bool
+ section_may_have_icf_unsafe_pointers(const char* section_name) const
+ {
+ // We recognize sections for normal vtables, construction vtables and
+ // EH frames.
+ return (!is_prefix_of(".rodata._ZTV", section_name)
+ && !is_prefix_of(".data.rel.ro._ZTV", section_name)
+ && !is_prefix_of(".rodata._ZTC", section_name)
+ && !is_prefix_of(".data.rel.ro._ZTC", section_name)
+ && !is_prefix_of(".eh_frame", section_name));
+ }
+
// Return the bit size that this target implements. This should
// return 32 or 64.
int
machine_code() const
{ return this->pti_->machine_code; }
+ // Processor specific flags to store in e_flags field of ELF header.
+ elfcpp::Elf_Word
+ processor_specific_flags() const
+ { return this->processor_specific_flags_; }
+
+ // Whether processor specific flags are set at least once.
+ bool
+ are_processor_specific_flags_set() const
+ { return this->are_processor_specific_flags_set_; }
+
// Whether this target has a specific make_symbol function.
bool
has_make_symbol() const
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); }
+ finalize_sections(Layout* layout, const Input_objects* input_objects,
+ Symbol_table* symtab)
+ { return this->do_finalize_sections(layout, input_objects, symtab); }
// 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
// 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(Symbol* sym) const
+ 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); }
+
+ // Get the symbol index to use for a target specific reloc.
+ unsigned int
+ reloc_symbol_index(void* arg, unsigned int type) const
+ { return this->do_reloc_symbol_index(arg, type); }
+
+ // Get the addend to use for a target specific reloc.
+ uint64_t
+ reloc_addend(void* arg, unsigned int type, uint64_t addend) const
+ { return this->do_reloc_addend(arg, type, addend); }
+
+ // Return the PLT section to use for a global symbol. This is used
+ // for STT_GNU_IFUNC symbols.
+ Output_data*
+ plt_section_for_global(const Symbol* sym) const
+ { return this->do_plt_section_for_global(sym); }
+
+ // Return the PLT section to use for a local symbol. This is used
+ // for STT_GNU_IFUNC symbols.
+ Output_data*
+ plt_section_for_local(const Relobj* object, unsigned int symndx) const
+ { return this->do_plt_section_for_local(object, symndx); }
+
+ // Return true if a reference to SYM from a reloc of type R_TYPE
+ // means that the current function may call an object compiled
+ // without -fsplit-stack. SYM is known to be defined in an object
+ // compiled without -fsplit-stack.
+ bool
+ is_call_to_non_split(const Symbol* sym, unsigned int r_type) const
+ { return this->do_is_call_to_non_split(sym, r_type); }
+
+ // 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, const Task* task)
+ {
+ // 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, task);
+ }
+
+ // Return the target-specific name of attributes section. This is
+ // NULL if a target does not use attributes section or if it uses
+ // the default section name ".gnu.attributes".
+ const char*
+ attributes_section() const
+ { return this->pti_->attributes_section; }
+
+ // Return the vendor name of vendor attributes.
+ const char*
+ attributes_vendor() const
+ { return this->pti_->attributes_vendor; }
+
+ // Whether a section called NAME is an attribute section.
+ bool
+ is_attributes_section(const char* name) const
+ {
+ return ((this->pti_->attributes_section != NULL
+ && strcmp(name, this->pti_->attributes_section) == 0)
+ || strcmp(name, ".gnu.attributes") == 0);
+ }
+
+ // Return a bit mask of argument types for attribute with TAG.
+ int
+ attribute_arg_type(int tag) const
+ { return this->do_attribute_arg_type(tag); }
+
+ // Return the attribute tag of the position NUM in the list of fixed
+ // attributes. Normally there is no reordering and
+ // attributes_order(NUM) == NUM.
+ int
+ attributes_order(int num) const
+ { return this->do_attributes_order(num); }
+
+ // When a target is selected as the default target, we call this method,
+ // which may be used for expensive, target-specific initialization.
+ void
+ select_as_default_target()
+ { this->do_select_as_default_target(); }
+
protected:
// This struct holds the constant information for a child class. We
// use a struct to avoid the overhead of virtual function calls for
// 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 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;
+ // Name of attributes section if it is not ".gnu.attributes".
+ const char* attributes_section;
+ // Vendor name of vendor attributes.
+ const char* attributes_vendor;
};
Target(const Target_info* pti)
- : pti_(pti)
+ : pti_(pti), processor_specific_flags_(0),
+ are_processor_specific_flags_set_(false)
+ { }
+
+ // 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*)
+ do_finalize_sections(Layout*, const Input_objects*, Symbol_table*)
{ }
// Virtual function which may be implemented by the child class.
// Virtual function which may be implemented by the child class.
virtual bool
- do_is_defined_by_abi(Symbol*) const
+ 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 overridden by the child class.
+ virtual bool
+ do_is_local_label_name(const char*) const;
+
+ // Virtual function that must be overridden by a target which uses
+ // target specific relocations.
+ virtual unsigned int
+ do_reloc_symbol_index(void*, unsigned int) const
+ { gold_unreachable(); }
+
+ // Virtual function that must be overridden by a target which uses
+ // target specific relocations.
+ virtual uint64_t
+ do_reloc_addend(void*, unsigned int, uint64_t) const
+ { gold_unreachable(); }
+
+ // Virtual functions that must be overridden by a target that uses
+ // STT_GNU_IFUNC symbols.
+ virtual Output_data*
+ do_plt_section_for_global(const Symbol*) const
+ { gold_unreachable(); }
+
+ virtual Output_data*
+ do_plt_section_for_local(const Relobj*, unsigned int) const
+ { gold_unreachable(); }
+
+ // Virtual function which may be overridden by the child class. The
+ // default implementation is that any function not defined by the
+ // ABI is a call to a non-split function.
+ virtual bool
+ do_is_call_to_non_split(const Symbol* sym, unsigned int) 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 endianness.
+
+ // Set processor specific flags.
+ void
+ set_processor_specific_flags(elfcpp::Elf_Word flags)
+ {
+ this->processor_specific_flags_ = flags;
+ this->are_processor_specific_flags_set_ = true;
+ }
+
+#ifdef HAVE_TARGET_32_LITTLE
+ // Virtual functions which may be overridden 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 overridden 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 overridden 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 overridden 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 overridden 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 overridden by the child class.
+ virtual bool
+ do_may_relax() const
+ { return parameters->options().relax(); }
+
+ // Virtual function which may be overridden by the child class.
+ virtual bool
+ do_relax(int, const Input_objects*, Symbol_table*, Layout*, const Task*)
{ 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;
+
+ // This must be overridden by the child class if it has target-specific
+ // attributes subsection in the attribute section.
+ virtual int
+ do_attribute_arg_type(int) const
+ { gold_unreachable(); }
+
+ // This may be overridden by the child class.
+ virtual int
+ do_attributes_order(int num) const
+ { return num; }
+
+ // This may be overridden by the child class.
+ virtual void
+ do_select_as_default_target()
+ { }
+
private:
+ // The implementations of the four do_make_elf_object virtual functions are
+ // almost identical except for their sizes and endianness. 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_;
+ // Processor-specific flags.
+ elfcpp::Elf_Word processor_specific_flags_;
+ // Whether the processor-specific flags are set at least once.
+ bool are_processor_specific_flags_set_;
};
// The abstract class for a specific size and endianness of target.
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(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.
+ // required for the symbol. 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,
+ scan_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj<size, big_endian>* object,
unsigned int data_shndx,
bool needs_special_offset_handling,
unsigned char* view,
typename elfcpp::Elf_types<size>::Elf_Addr view_address,
- section_size_type view_size) = 0;
+ 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,
+ scan_relocatable_relocs(Symbol_table* symtab,
Layout* layout,
Sized_relobj<size, big_endian>* object,
unsigned int data_shndx,
section_size_type view_size,
unsigned char* reloc_view,
section_size_type reloc_view_size) = 0;
+
+ // Perform target-specific processing in a relocatable link. This is
+ // only used if we use the relocation strategy RELOC_SPECIAL.
+ // RELINFO points to a Relocation_info structure. SH_TYPE is the relocation
+ // section type. PRELOC_IN points to the original relocation. RELNUM is
+ // the index number of the relocation in the relocation section.
+ // OUTPUT_SECTION is the output section to which the relocation is applied.
+ // OFFSET_IN_OUTPUT_SECTION is the offset of the relocation input section
+ // within the output section. VIEW points to the output view of the
+ // output section. VIEW_ADDRESS is output address of the view. VIEW_SIZE
+ // is the size of the output view and PRELOC_OUT points to the new
+ // relocation in the output object.
+ //
+ // A target only needs to override this if the generic code in
+ // target-reloc.h cannot handle some relocation types.
+
+ virtual void
+ relocate_special_relocatable(const Relocate_info<size, big_endian>*
+ /*relinfo */,
+ unsigned int /* sh_type */,
+ const unsigned char* /* preloc_in */,
+ size_t /* relnum */,
+ Output_section* /* output_section */,
+ off_t /* offset_in_output_section */,
+ unsigned char* /* view */,
+ typename elfcpp::Elf_types<size>::Elf_Addr
+ /* view_address */,
+ section_size_type /* view_size */,
+ unsigned char* /* preloc_out*/)
+ { gold_unreachable(); }
+
+ // Return the number of entries in the GOT. This is only used for
+ // laying out the incremental link info sections. A target needs
+ // to implement this to support incremental linking.
+
+ virtual unsigned int
+ got_entry_count() const
+ { gold_unreachable(); }
+
+ // Return the number of entries in the PLT. This is only used for
+ // laying out the incremental link info sections. A target needs
+ // to implement this to support incremental linking.
+
+ virtual unsigned int
+ plt_entry_count() const
+ { gold_unreachable(); }
+
+ // Return the offset of the first non-reserved PLT entry. This is
+ // only used for laying out the incremental link info sections.
+ // A target needs to implement this to support incremental linking.
+
+ virtual unsigned int
+ first_plt_entry_offset() const
+ { gold_unreachable(); }
+
+ // Return the size of each PLT entry. This is only used for
+ // laying out the incremental link info sections. A target needs
+ // to implement this to support incremental linking.
+
+ virtual unsigned int
+ plt_entry_size() const
+ { gold_unreachable(); }
protected:
Sized_target(const Target::Target_info* pti)
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