1 // target.h -- target support for gold -*- C++ -*-
3 // Copyright (C) 2006-2016 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
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.
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.
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.
23 // The abstract class Target is the interface for target specific
24 // support. It defines abstract methods which each target must
25 // implement. Typically there will be one target per processor, but
26 // in some cases it may be necessary to have subclasses.
28 // For speed and consistency we want to use inline functions to handle
29 // relocation processing. So besides implementations of the abstract
30 // methods, each target is expected to define a template
31 // specialization of the relocation functions.
38 #include "parameters.h"
39 #include "stringpool.h"
47 template<int size
, bool big_endian
>
49 template<int size
, bool big_endian
>
50 class Sized_relobj_file
;
51 class Relocatable_relocs
;
52 template<int size
, bool big_endian
>
54 class Reloc_symbol_changes
;
60 class Output_data_got_base
;
64 struct Symbol_location
;
67 // The abstract class for target specific handling.
75 // Return the bit size that this target implements. This should
79 { return this->pti_
->size
; }
81 // Return whether this target is big-endian.
84 { return this->pti_
->is_big_endian
; }
86 // Machine code to store in e_machine field of ELF header.
89 { return this->pti_
->machine_code
; }
91 // Processor specific flags to store in e_flags field of ELF header.
93 processor_specific_flags() const
94 { return this->processor_specific_flags_
; }
96 // Whether processor specific flags are set at least once.
98 are_processor_specific_flags_set() const
99 { return this->are_processor_specific_flags_set_
; }
101 // Whether this target has a specific make_symbol function.
103 has_make_symbol() const
104 { return this->pti_
->has_make_symbol
; }
106 // Whether this target has a specific resolve function.
109 { return this->pti_
->has_resolve
; }
111 // Whether this target has a specific code fill function.
113 has_code_fill() const
114 { return this->pti_
->has_code_fill
; }
116 // Return the default name of the dynamic linker.
118 dynamic_linker() const
119 { return this->pti_
->dynamic_linker
; }
121 // Return the default address to use for the text segment.
123 default_text_segment_address() const
124 { return this->pti_
->default_text_segment_address
; }
126 // Return the ABI specified page size.
130 if (parameters
->options().max_page_size() > 0)
131 return parameters
->options().max_page_size();
133 return this->pti_
->abi_pagesize
;
136 // Return the common page size used on actual systems.
138 common_pagesize() const
140 if (parameters
->options().common_page_size() > 0)
141 return std::min(parameters
->options().common_page_size(),
142 this->abi_pagesize());
144 return std::min(this->pti_
->common_pagesize
,
145 this->abi_pagesize());
148 // Return whether PF_X segments must contain nothing but the contents of
149 // SHF_EXECINSTR sections (no non-executable data, no headers).
151 isolate_execinstr() const
152 { return this->pti_
->isolate_execinstr
; }
155 rosegment_gap() const
156 { return this->pti_
->rosegment_gap
; }
158 // If we see some object files with .note.GNU-stack sections, and
159 // some objects files without them, this returns whether we should
160 // consider the object files without them to imply that the stack
161 // should be executable.
163 is_default_stack_executable() const
164 { return this->pti_
->is_default_stack_executable
; }
166 // Return a character which may appear as a prefix for a wrap
167 // symbol. If this character appears, we strip it when checking for
168 // wrapping and add it back when forming the final symbol name.
169 // This should be '\0' if not special prefix is required, which is
173 { return this->pti_
->wrap_char
; }
175 // Return the special section index which indicates a small common
176 // symbol. This will return SHN_UNDEF if there are no small common
179 small_common_shndx() const
180 { return this->pti_
->small_common_shndx
; }
182 // Return values to add to the section flags for the section holding
183 // small common symbols.
185 small_common_section_flags() const
187 gold_assert(this->pti_
->small_common_shndx
!= elfcpp::SHN_UNDEF
);
188 return this->pti_
->small_common_section_flags
;
191 // Return the special section index which indicates a large common
192 // symbol. This will return SHN_UNDEF if there are no large common
195 large_common_shndx() const
196 { return this->pti_
->large_common_shndx
; }
198 // Return values to add to the section flags for the section holding
199 // large common symbols.
201 large_common_section_flags() const
203 gold_assert(this->pti_
->large_common_shndx
!= elfcpp::SHN_UNDEF
);
204 return this->pti_
->large_common_section_flags
;
207 // This hook is called when an output section is created.
209 new_output_section(Output_section
* os
) const
210 { this->do_new_output_section(os
); }
212 // This is called to tell the target to complete any sections it is
213 // handling. After this all sections must have their final size.
215 finalize_sections(Layout
* layout
, const Input_objects
* input_objects
,
216 Symbol_table
* symtab
)
217 { return this->do_finalize_sections(layout
, input_objects
, symtab
); }
219 // Return the value to use for a global symbol which needs a special
220 // value in the dynamic symbol table. This will only be called if
221 // the backend first calls symbol->set_needs_dynsym_value().
223 dynsym_value(const Symbol
* sym
) const
224 { return this->do_dynsym_value(sym
); }
226 // Return a string to use to fill out a code section. This is
227 // basically one or more NOPS which must fill out the specified
230 code_fill(section_size_type length
) const
231 { return this->do_code_fill(length
); }
233 // Return whether SYM is known to be defined by the ABI. This is
234 // used to avoid inappropriate warnings about undefined symbols.
236 is_defined_by_abi(const Symbol
* sym
) const
237 { return this->do_is_defined_by_abi(sym
); }
239 // Adjust the output file header before it is written out. VIEW
240 // points to the header in external form. LEN is the length.
242 adjust_elf_header(unsigned char* view
, int len
)
243 { return this->do_adjust_elf_header(view
, len
); }
245 // Return address and size to plug into eh_frame FDEs associated with a PLT.
247 plt_fde_location(const Output_data
* plt
, unsigned char* oview
,
248 uint64_t* address
, off_t
* len
) const
249 { return this->do_plt_fde_location(plt
, oview
, address
, len
); }
251 // Return whether NAME is a local label name. This is used to implement the
252 // --discard-locals options.
254 is_local_label_name(const char* name
) const
255 { return this->do_is_local_label_name(name
); }
257 // Get the symbol index to use for a target specific reloc.
259 reloc_symbol_index(void* arg
, unsigned int type
) const
260 { return this->do_reloc_symbol_index(arg
, type
); }
262 // Get the addend to use for a target specific reloc.
264 reloc_addend(void* arg
, unsigned int type
, uint64_t addend
) const
265 { return this->do_reloc_addend(arg
, type
, addend
); }
267 // Return the PLT address to use for a global symbol.
269 plt_address_for_global(const Symbol
* sym
) const
270 { return this->do_plt_address_for_global(sym
); }
272 // Return the PLT address to use for a local symbol.
274 plt_address_for_local(const Relobj
* object
, unsigned int symndx
) const
275 { return this->do_plt_address_for_local(object
, symndx
); }
277 // Return the offset to use for the GOT_INDX'th got entry which is
278 // for a local tls symbol specified by OBJECT, SYMNDX.
280 tls_offset_for_local(const Relobj
* object
,
282 unsigned int got_indx
) const
283 { return do_tls_offset_for_local(object
, symndx
, got_indx
); }
285 // Return the offset to use for the GOT_INDX'th got entry which is
286 // for global tls symbol GSYM.
288 tls_offset_for_global(Symbol
* gsym
, unsigned int got_indx
) const
289 { return do_tls_offset_for_global(gsym
, got_indx
); }
291 // For targets that use function descriptors, if LOC is the location
292 // of a function, modify it to point at the function entry location.
294 function_location(Symbol_location
* loc
) const
295 { return do_function_location(loc
); }
297 // Return whether this target can use relocation types to determine
298 // if a function's address is taken.
300 can_check_for_function_pointers() const
301 { return this->do_can_check_for_function_pointers(); }
303 // Return whether a relocation to a merged section can be processed
304 // to retrieve the contents.
306 can_icf_inline_merge_sections () const
307 { return this->pti_
->can_icf_inline_merge_sections
; }
309 // Whether a section called SECTION_NAME may have function pointers to
310 // sections not eligible for safe ICF folding.
312 section_may_have_icf_unsafe_pointers(const char* section_name
) const
313 { return this->do_section_may_have_icf_unsafe_pointers(section_name
); }
315 // Return the base to use for the PC value in an FDE when it is
316 // encoded using DW_EH_PE_datarel. This does not appear to be
317 // documented anywhere, but it is target specific. Any use of
318 // DW_EH_PE_datarel in gcc requires defining a special macro
319 // (ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX) to output the value.
321 ehframe_datarel_base() const
322 { return this->do_ehframe_datarel_base(); }
324 // Return true if a reference to SYM from a reloc at *PRELOC
325 // means that the current function may call an object compiled
326 // without -fsplit-stack. SYM is known to be defined in an object
327 // compiled without -fsplit-stack.
329 is_call_to_non_split(const Symbol
* sym
, const unsigned char* preloc
,
330 const unsigned char* view
,
331 section_size_type view_size
) const
332 { return this->do_is_call_to_non_split(sym
, preloc
, view
, view_size
); }
334 // A function starts at OFFSET in section SHNDX in OBJECT. That
335 // function was compiled with -fsplit-stack, but it refers to a
336 // function which was compiled without -fsplit-stack. VIEW is a
337 // modifiable view of the section; VIEW_SIZE is the size of the
338 // view. The target has to adjust the function so that it allocates
341 calls_non_split(Relobj
* object
, unsigned int shndx
,
342 section_offset_type fnoffset
, section_size_type fnsize
,
343 const unsigned char* prelocs
, size_t reloc_count
,
344 unsigned char* view
, section_size_type view_size
,
345 std::string
* from
, std::string
* to
) const
347 this->do_calls_non_split(object
, shndx
, fnoffset
, fnsize
,
348 prelocs
, reloc_count
, view
, view_size
,
352 // Make an ELF object.
353 template<int size
, bool big_endian
>
355 make_elf_object(const std::string
& name
, Input_file
* input_file
,
356 off_t offset
, const elfcpp::Ehdr
<size
, big_endian
>& ehdr
)
357 { return this->do_make_elf_object(name
, input_file
, offset
, ehdr
); }
359 // Make an output section.
361 make_output_section(const char* name
, elfcpp::Elf_Word type
,
362 elfcpp::Elf_Xword flags
)
363 { return this->do_make_output_section(name
, type
, flags
); }
365 // Return true if target wants to perform relaxation.
369 // Run the dummy relaxation pass twice if relaxation debugging is enabled.
370 if (is_debugging_enabled(DEBUG_RELAXATION
))
373 return this->do_may_relax();
376 // Perform a relaxation pass. Return true if layout may be changed.
378 relax(int pass
, const Input_objects
* input_objects
, Symbol_table
* symtab
,
379 Layout
* layout
, const Task
* task
)
381 // Run the dummy relaxation pass twice if relaxation debugging is enabled.
382 if (is_debugging_enabled(DEBUG_RELAXATION
))
385 return this->do_relax(pass
, input_objects
, symtab
, layout
, task
);
388 // Return the target-specific name of attributes section. This is
389 // NULL if a target does not use attributes section or if it uses
390 // the default section name ".gnu.attributes".
392 attributes_section() const
393 { return this->pti_
->attributes_section
; }
395 // Return the vendor name of vendor attributes.
397 attributes_vendor() const
398 { return this->pti_
->attributes_vendor
; }
400 // Whether a section called NAME is an attribute section.
402 is_attributes_section(const char* name
) const
404 return ((this->pti_
->attributes_section
!= NULL
405 && strcmp(name
, this->pti_
->attributes_section
) == 0)
406 || strcmp(name
, ".gnu.attributes") == 0);
409 // Return a bit mask of argument types for attribute with TAG.
411 attribute_arg_type(int tag
) const
412 { return this->do_attribute_arg_type(tag
); }
414 // Return the attribute tag of the position NUM in the list of fixed
415 // attributes. Normally there is no reordering and
416 // attributes_order(NUM) == NUM.
418 attributes_order(int num
) const
419 { return this->do_attributes_order(num
); }
421 // When a target is selected as the default target, we call this method,
422 // which may be used for expensive, target-specific initialization.
424 select_as_default_target()
425 { this->do_select_as_default_target(); }
427 // Return the value to store in the EI_OSABI field in the ELF
431 { return this->osabi_
; }
433 // Set the value to store in the EI_OSABI field in the ELF header.
435 set_osabi(elfcpp::ELFOSABI osabi
)
436 { this->osabi_
= osabi
; }
438 // Define target-specific standard symbols.
440 define_standard_symbols(Symbol_table
* symtab
, Layout
* layout
)
441 { this->do_define_standard_symbols(symtab
, layout
); }
443 // Return the output section name to use given an input section
444 // name, or NULL if no target specific name mapping is required.
445 // Set *PLEN to the length of the name if returning non-NULL.
447 output_section_name(const Relobj
* relobj
,
450 { return this->do_output_section_name(relobj
, name
, plen
); }
452 // Add any special sections for this symbol to the gc work list.
454 gc_mark_symbol(Symbol_table
* symtab
, Symbol
* sym
) const
455 { this->do_gc_mark_symbol(symtab
, sym
); }
457 // Return the name of the entry point symbol.
459 entry_symbol_name() const
460 { return this->pti_
->entry_symbol_name
; }
462 // Return the size in bits of SHT_HASH entry.
464 hash_entry_size() const
465 { return this->pti_
->hash_entry_size
; }
467 // Whether the target has a custom set_dynsym_indexes method.
469 has_custom_set_dynsym_indexes() const
470 { return this->do_has_custom_set_dynsym_indexes(); }
472 // Custom set_dynsym_indexes method for a target.
474 set_dynsym_indexes(std::vector
<Symbol
*>* dyn_symbols
, unsigned int index
,
475 std::vector
<Symbol
*>* syms
, Stringpool
* dynpool
,
476 Versions
* versions
, Symbol_table
* symtab
) const
478 return this->do_set_dynsym_indexes(dyn_symbols
, index
, syms
, dynpool
,
482 // Get the custom dynamic tag value.
484 dynamic_tag_custom_value(elfcpp::DT tag
) const
485 { return this->do_dynamic_tag_custom_value(tag
); }
487 // Adjust the value written to the dynamic symbol table.
489 adjust_dyn_symbol(const Symbol
* sym
, unsigned char* view
) const
490 { this->do_adjust_dyn_symbol(sym
, view
); }
492 // Return whether to include the section in the link.
494 should_include_section(elfcpp::Elf_Word sh_type
) const
495 { return this->do_should_include_section(sh_type
); }
498 // This struct holds the constant information for a child class. We
499 // use a struct to avoid the overhead of virtual function calls for
500 // simple information.
503 // Address size (32 or 64).
505 // Whether the target is big endian.
507 // The code to store in the e_machine field of the ELF header.
508 elfcpp::EM machine_code
;
509 // Whether this target has a specific make_symbol function.
510 bool has_make_symbol
;
511 // Whether this target has a specific resolve function.
513 // Whether this target has a specific code fill function.
515 // Whether an object file with no .note.GNU-stack sections implies
516 // that the stack should be executable.
517 bool is_default_stack_executable
;
518 // Whether a relocation to a merged section can be processed to
519 // retrieve the contents.
520 bool can_icf_inline_merge_sections
;
521 // Prefix character to strip when checking for wrapping.
523 // The default dynamic linker name.
524 const char* dynamic_linker
;
525 // The default text segment address.
526 uint64_t default_text_segment_address
;
527 // The ABI specified page size.
528 uint64_t abi_pagesize
;
529 // The common page size used by actual implementations.
530 uint64_t common_pagesize
;
531 // Whether PF_X segments must contain nothing but the contents of
532 // SHF_EXECINSTR sections (no non-executable data, no headers).
533 bool isolate_execinstr
;
534 // If nonzero, distance from the text segment to the read-only segment.
535 uint64_t rosegment_gap
;
536 // The special section index for small common symbols; SHN_UNDEF
538 elfcpp::Elf_Half small_common_shndx
;
539 // The special section index for large common symbols; SHN_UNDEF
541 elfcpp::Elf_Half large_common_shndx
;
542 // Section flags for small common section.
543 elfcpp::Elf_Xword small_common_section_flags
;
544 // Section flags for large common section.
545 elfcpp::Elf_Xword large_common_section_flags
;
546 // Name of attributes section if it is not ".gnu.attributes".
547 const char* attributes_section
;
548 // Vendor name of vendor attributes.
549 const char* attributes_vendor
;
550 // Name of the main entry point to the program.
551 const char* entry_symbol_name
;
552 // Size (in bits) of SHT_HASH entry. Always equal to 32, except for
554 const int hash_entry_size
;
557 Target(const Target_info
* pti
)
558 : pti_(pti
), processor_specific_flags_(0),
559 are_processor_specific_flags_set_(false), osabi_(elfcpp::ELFOSABI_NONE
)
562 // Virtual function which may be implemented by the child class.
564 do_new_output_section(Output_section
*) const
567 // Virtual function which may be implemented by the child class.
569 do_finalize_sections(Layout
*, const Input_objects
*, Symbol_table
*)
572 // Virtual function which may be implemented by the child class.
574 do_dynsym_value(const Symbol
*) const
575 { gold_unreachable(); }
577 // Virtual function which must be implemented by the child class if
580 do_code_fill(section_size_type
) const
581 { gold_unreachable(); }
583 // Virtual function which may be implemented by the child class.
585 do_is_defined_by_abi(const Symbol
*) const
588 // Adjust the output file header before it is written out. VIEW
589 // points to the header in external form. LEN is the length, and
590 // will be one of the values of elfcpp::Elf_sizes<size>::ehdr_size.
591 // By default, we set the EI_OSABI field if requested (in
594 do_adjust_elf_header(unsigned char*, int) = 0;
596 // Return address and size to plug into eh_frame FDEs associated with a PLT.
598 do_plt_fde_location(const Output_data
* plt
, unsigned char* oview
,
599 uint64_t* address
, off_t
* len
) const;
601 // Virtual function which may be overridden by the child class.
603 do_is_local_label_name(const char*) const;
605 // Virtual function that must be overridden by a target which uses
606 // target specific relocations.
608 do_reloc_symbol_index(void*, unsigned int) const
609 { gold_unreachable(); }
611 // Virtual function that must be overridden by a target which uses
612 // target specific relocations.
614 do_reloc_addend(void*, unsigned int, uint64_t) const
615 { gold_unreachable(); }
617 // Virtual functions that must be overridden by a target that uses
618 // STT_GNU_IFUNC symbols.
620 do_plt_address_for_global(const Symbol
*) const
621 { gold_unreachable(); }
624 do_plt_address_for_local(const Relobj
*, unsigned int) const
625 { gold_unreachable(); }
628 do_tls_offset_for_local(const Relobj
*, unsigned int, unsigned int) const
629 { gold_unreachable(); }
632 do_tls_offset_for_global(Symbol
*, unsigned int) const
633 { gold_unreachable(); }
636 do_function_location(Symbol_location
*) const = 0;
638 // Virtual function which may be overriden by the child class.
640 do_can_check_for_function_pointers() const
643 // Virtual function which may be overridden by the child class. We
644 // recognize some default sections for which we don't care whether
645 // they have function pointers.
647 do_section_may_have_icf_unsafe_pointers(const char* section_name
) const
649 // We recognize sections for normal vtables, construction vtables and
651 return (!is_prefix_of(".rodata._ZTV", section_name
)
652 && !is_prefix_of(".data.rel.ro._ZTV", section_name
)
653 && !is_prefix_of(".rodata._ZTC", section_name
)
654 && !is_prefix_of(".data.rel.ro._ZTC", section_name
)
655 && !is_prefix_of(".eh_frame", section_name
));
659 do_ehframe_datarel_base() const
660 { gold_unreachable(); }
662 // Virtual function which may be overridden by the child class. The
663 // default implementation is that any function not defined by the
664 // ABI is a call to a non-split function.
666 do_is_call_to_non_split(const Symbol
* sym
, const unsigned char*,
667 const unsigned char*, section_size_type
) const;
669 // Virtual function which may be overridden by the child class.
671 do_calls_non_split(Relobj
* object
, unsigned int, section_offset_type
,
672 section_size_type
, const unsigned char*, size_t,
673 unsigned char*, section_size_type
,
674 std::string
*, std::string
*) const;
676 // make_elf_object hooks. There are four versions of these for
677 // different address sizes and endianness.
679 // Set processor specific flags.
681 set_processor_specific_flags(elfcpp::Elf_Word flags
)
683 this->processor_specific_flags_
= flags
;
684 this->are_processor_specific_flags_set_
= true;
687 #ifdef HAVE_TARGET_32_LITTLE
688 // Virtual functions which may be overridden by the child class.
690 do_make_elf_object(const std::string
&, Input_file
*, off_t
,
691 const elfcpp::Ehdr
<32, false>&);
694 #ifdef HAVE_TARGET_32_BIG
695 // Virtual functions which may be overridden by the child class.
697 do_make_elf_object(const std::string
&, Input_file
*, off_t
,
698 const elfcpp::Ehdr
<32, true>&);
701 #ifdef HAVE_TARGET_64_LITTLE
702 // Virtual functions which may be overridden by the child class.
704 do_make_elf_object(const std::string
&, Input_file
*, off_t
,
705 const elfcpp::Ehdr
<64, false>& ehdr
);
708 #ifdef HAVE_TARGET_64_BIG
709 // Virtual functions which may be overridden by the child class.
711 do_make_elf_object(const std::string
& name
, Input_file
* input_file
,
712 off_t offset
, const elfcpp::Ehdr
<64, true>& ehdr
);
715 // Virtual functions which may be overridden by the child class.
716 virtual Output_section
*
717 do_make_output_section(const char* name
, elfcpp::Elf_Word type
,
718 elfcpp::Elf_Xword flags
);
720 // Virtual function which may be overridden by the child class.
723 { return parameters
->options().relax(); }
725 // Virtual function which may be overridden by the child class.
727 do_relax(int, const Input_objects
*, Symbol_table
*, Layout
*, const Task
*)
730 // A function for targets to call. Return whether BYTES/LEN matches
731 // VIEW/VIEW_SIZE at OFFSET.
733 match_view(const unsigned char* view
, section_size_type view_size
,
734 section_offset_type offset
, const char* bytes
, size_t len
) const;
736 // Set the contents of a VIEW/VIEW_SIZE to nops starting at OFFSET
739 set_view_to_nop(unsigned char* view
, section_size_type view_size
,
740 section_offset_type offset
, size_t len
) const;
742 // This must be overridden by the child class if it has target-specific
743 // attributes subsection in the attribute section.
745 do_attribute_arg_type(int) const
746 { gold_unreachable(); }
748 // This may be overridden by the child class.
750 do_attributes_order(int num
) const
753 // This may be overridden by the child class.
755 do_select_as_default_target()
758 // This may be overridden by the child class.
760 do_define_standard_symbols(Symbol_table
*, Layout
*)
763 // This may be overridden by the child class.
765 do_output_section_name(const Relobj
*, const char*, size_t*) const
768 // This may be overridden by the child class.
770 do_gc_mark_symbol(Symbol_table
*, Symbol
*) const
773 // This may be overridden by the child class.
775 do_has_custom_set_dynsym_indexes() const
778 // This may be overridden by the child class.
780 do_set_dynsym_indexes(std::vector
<Symbol
*>*, unsigned int,
781 std::vector
<Symbol
*>*, Stringpool
*, Versions
*,
783 { gold_unreachable(); }
785 // This may be overridden by the child class.
787 do_dynamic_tag_custom_value(elfcpp::DT
) const
788 { gold_unreachable(); }
790 // This may be overridden by the child class.
792 do_adjust_dyn_symbol(const Symbol
*, unsigned char*) const
795 // This may be overridden by the child class.
797 do_should_include_section(elfcpp::Elf_Word
) const
801 // The implementations of the four do_make_elf_object virtual functions are
802 // almost identical except for their sizes and endianness. We use a template.
803 // for their implementations.
804 template<int size
, bool big_endian
>
806 do_make_elf_object_implementation(const std::string
&, Input_file
*, off_t
,
807 const elfcpp::Ehdr
<size
, big_endian
>&);
809 Target(const Target
&);
810 Target
& operator=(const Target
&);
812 // The target information.
813 const Target_info
* pti_
;
814 // Processor-specific flags.
815 elfcpp::Elf_Word processor_specific_flags_
;
816 // Whether the processor-specific flags are set at least once.
817 bool are_processor_specific_flags_set_
;
818 // If not ELFOSABI_NONE, the value to put in the EI_OSABI field of
819 // the ELF header. This is handled at this level because it is
820 // OS-specific rather than processor-specific.
821 elfcpp::ELFOSABI osabi_
;
824 // The abstract class for a specific size and endianness of target.
825 // Each actual target implementation class should derive from an
826 // instantiation of Sized_target.
828 template<int size
, bool big_endian
>
829 class Sized_target
: public Target
832 // Make a new symbol table entry for the target. This should be
833 // overridden by a target which needs additional information in the
834 // symbol table. This will only be called if has_make_symbol()
836 virtual Sized_symbol
<size
>*
838 { gold_unreachable(); }
840 // Resolve a symbol for the target. This should be overridden by a
841 // target which needs to take special action. TO is the
842 // pre-existing symbol. SYM is the new symbol, seen in OBJECT.
843 // VERSION is the version of SYM. This will only be called if
844 // has_resolve() returns true.
846 resolve(Symbol
*, const elfcpp::Sym
<size
, big_endian
>&, Object
*,
848 { gold_unreachable(); }
850 // Process the relocs for a section, and record information of the
851 // mapping from source to destination sections. This mapping is later
852 // used to determine unreferenced garbage sections. This procedure is
853 // only called during garbage collection.
855 gc_process_relocs(Symbol_table
* symtab
,
857 Sized_relobj_file
<size
, big_endian
>* object
,
858 unsigned int data_shndx
,
859 unsigned int sh_type
,
860 const unsigned char* prelocs
,
862 Output_section
* output_section
,
863 bool needs_special_offset_handling
,
864 size_t local_symbol_count
,
865 const unsigned char* plocal_symbols
) = 0;
867 // Scan the relocs for a section, and record any information
868 // required for the symbol. SYMTAB is the symbol table. OBJECT is
869 // the object in which the section appears. DATA_SHNDX is the
870 // section index that these relocs apply to. SH_TYPE is the type of
871 // the relocation section, SHT_REL or SHT_RELA. PRELOCS points to
872 // the relocation data. RELOC_COUNT is the number of relocs.
873 // LOCAL_SYMBOL_COUNT is the number of local symbols.
874 // OUTPUT_SECTION is the output section.
875 // NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets to the output
876 // sections are not mapped as usual. PLOCAL_SYMBOLS points to the
877 // local symbol data from OBJECT. GLOBAL_SYMBOLS is the array of
878 // pointers to the global symbol table from OBJECT.
880 scan_relocs(Symbol_table
* symtab
,
882 Sized_relobj_file
<size
, big_endian
>* object
,
883 unsigned int data_shndx
,
884 unsigned int sh_type
,
885 const unsigned char* prelocs
,
887 Output_section
* output_section
,
888 bool needs_special_offset_handling
,
889 size_t local_symbol_count
,
890 const unsigned char* plocal_symbols
) = 0;
892 // Relocate section data. SH_TYPE is the type of the relocation
893 // section, SHT_REL or SHT_RELA. PRELOCS points to the relocation
894 // information. RELOC_COUNT is the number of relocs.
895 // OUTPUT_SECTION is the output section.
896 // NEEDS_SPECIAL_OFFSET_HANDLING is true if offsets must be mapped
897 // to correspond to the output section. VIEW is a view into the
898 // output file holding the section contents, VIEW_ADDRESS is the
899 // virtual address of the view, and VIEW_SIZE is the size of the
900 // view. If NEEDS_SPECIAL_OFFSET_HANDLING is true, the VIEW_xx
901 // parameters refer to the complete output section data, not just
902 // the input section data.
904 relocate_section(const Relocate_info
<size
, big_endian
>*,
905 unsigned int sh_type
,
906 const unsigned char* prelocs
,
908 Output_section
* output_section
,
909 bool needs_special_offset_handling
,
911 typename
elfcpp::Elf_types
<size
>::Elf_Addr view_address
,
912 section_size_type view_size
,
913 const Reloc_symbol_changes
*) = 0;
915 // Scan the relocs during a relocatable link. The parameters are
916 // like scan_relocs, with an additional Relocatable_relocs
917 // parameter, used to record the disposition of the relocs.
919 scan_relocatable_relocs(Symbol_table
* symtab
,
921 Sized_relobj_file
<size
, big_endian
>* object
,
922 unsigned int data_shndx
,
923 unsigned int sh_type
,
924 const unsigned char* prelocs
,
926 Output_section
* output_section
,
927 bool needs_special_offset_handling
,
928 size_t local_symbol_count
,
929 const unsigned char* plocal_symbols
,
930 Relocatable_relocs
*) = 0;
932 // Scan the relocs for --emit-relocs. The parameters are
933 // like scan_relocatable_relocs.
935 emit_relocs_scan(Symbol_table
* symtab
,
937 Sized_relobj_file
<size
, big_endian
>* object
,
938 unsigned int data_shndx
,
939 unsigned int sh_type
,
940 const unsigned char* prelocs
,
942 Output_section
* output_section
,
943 bool needs_special_offset_handling
,
944 size_t local_symbol_count
,
945 const unsigned char* plocal_syms
,
946 Relocatable_relocs
* rr
) = 0;
948 // Emit relocations for a section during a relocatable link, and for
949 // --emit-relocs. The parameters are like relocate_section, with
950 // additional parameters for the view of the output reloc section.
952 relocate_relocs(const Relocate_info
<size
, big_endian
>*,
953 unsigned int sh_type
,
954 const unsigned char* prelocs
,
956 Output_section
* output_section
,
957 typename
elfcpp::Elf_types
<size
>::Elf_Off
958 offset_in_output_section
,
960 typename
elfcpp::Elf_types
<size
>::Elf_Addr view_address
,
961 section_size_type view_size
,
962 unsigned char* reloc_view
,
963 section_size_type reloc_view_size
) = 0;
965 // Perform target-specific processing in a relocatable link. This is
966 // only used if we use the relocation strategy RELOC_SPECIAL.
967 // RELINFO points to a Relocation_info structure. SH_TYPE is the relocation
968 // section type. PRELOC_IN points to the original relocation. RELNUM is
969 // the index number of the relocation in the relocation section.
970 // OUTPUT_SECTION is the output section to which the relocation is applied.
971 // OFFSET_IN_OUTPUT_SECTION is the offset of the relocation input section
972 // within the output section. VIEW points to the output view of the
973 // output section. VIEW_ADDRESS is output address of the view. VIEW_SIZE
974 // is the size of the output view and PRELOC_OUT points to the new
975 // relocation in the output object.
977 // A target only needs to override this if the generic code in
978 // target-reloc.h cannot handle some relocation types.
981 relocate_special_relocatable(const Relocate_info
<size
, big_endian
>*
983 unsigned int /* sh_type */,
984 const unsigned char* /* preloc_in */,
986 Output_section
* /* output_section */,
987 typename
elfcpp::Elf_types
<size
>::Elf_Off
988 /* offset_in_output_section */,
989 unsigned char* /* view */,
990 typename
elfcpp::Elf_types
<size
>::Elf_Addr
992 section_size_type
/* view_size */,
993 unsigned char* /* preloc_out*/)
994 { gold_unreachable(); }
996 // Return the number of entries in the GOT. This is only used for
997 // laying out the incremental link info sections. A target needs
998 // to implement this to support incremental linking.
1000 virtual unsigned int
1001 got_entry_count() const
1002 { gold_unreachable(); }
1004 // Return the number of entries in the PLT. This is only used for
1005 // laying out the incremental link info sections. A target needs
1006 // to implement this to support incremental linking.
1008 virtual unsigned int
1009 plt_entry_count() const
1010 { gold_unreachable(); }
1012 // Return the offset of the first non-reserved PLT entry. This is
1013 // only used for laying out the incremental link info sections.
1014 // A target needs to implement this to support incremental linking.
1016 virtual unsigned int
1017 first_plt_entry_offset() const
1018 { gold_unreachable(); }
1020 // Return the size of each PLT entry. This is only used for
1021 // laying out the incremental link info sections. A target needs
1022 // to implement this to support incremental linking.
1024 virtual unsigned int
1025 plt_entry_size() const
1026 { gold_unreachable(); }
1028 // Return the size of each GOT entry. This is only used for
1029 // laying out the incremental link info sections. A target needs
1030 // to implement this if its GOT size is different.
1032 virtual unsigned int
1033 got_entry_size() const
1034 { return size
/ 8; }
1036 // Create the GOT and PLT sections for an incremental update.
1037 // A target needs to implement this to support incremental linking.
1039 virtual Output_data_got_base
*
1040 init_got_plt_for_update(Symbol_table
*,
1042 unsigned int /* got_count */,
1043 unsigned int /* plt_count */)
1044 { gold_unreachable(); }
1046 // Reserve a GOT entry for a local symbol, and regenerate any
1047 // necessary dynamic relocations.
1049 reserve_local_got_entry(unsigned int /* got_index */,
1050 Sized_relobj
<size
, big_endian
>* /* obj */,
1051 unsigned int /* r_sym */,
1052 unsigned int /* got_type */)
1053 { gold_unreachable(); }
1055 // Reserve a GOT entry for a global symbol, and regenerate any
1056 // necessary dynamic relocations.
1058 reserve_global_got_entry(unsigned int /* got_index */, Symbol
* /* gsym */,
1059 unsigned int /* got_type */)
1060 { gold_unreachable(); }
1062 // Register an existing PLT entry for a global symbol.
1063 // A target needs to implement this to support incremental linking.
1066 register_global_plt_entry(Symbol_table
*, Layout
*,
1067 unsigned int /* plt_index */,
1069 { gold_unreachable(); }
1071 // Force a COPY relocation for a given symbol.
1072 // A target needs to implement this to support incremental linking.
1075 emit_copy_reloc(Symbol_table
*, Symbol
*, Output_section
*, off_t
)
1076 { gold_unreachable(); }
1078 // Apply an incremental relocation.
1081 apply_relocation(const Relocate_info
<size
, big_endian
>* /* relinfo */,
1082 typename
elfcpp::Elf_types
<size
>::Elf_Addr
/* r_offset */,
1083 unsigned int /* r_type */,
1084 typename
elfcpp::Elf_types
<size
>::Elf_Swxword
/* r_addend */,
1085 const Symbol
* /* gsym */,
1086 unsigned char* /* view */,
1087 typename
elfcpp::Elf_types
<size
>::Elf_Addr
/* address */,
1088 section_size_type
/* view_size */)
1089 { gold_unreachable(); }
1091 // Handle target specific gc actions when adding a gc reference from
1092 // SRC_OBJ, SRC_SHNDX to a location specified by DST_OBJ, DST_SHNDX
1095 gc_add_reference(Symbol_table
* symtab
,
1097 unsigned int src_shndx
,
1099 unsigned int dst_shndx
,
1100 typename
elfcpp::Elf_types
<size
>::Elf_Addr dst_off
) const
1102 this->do_gc_add_reference(symtab
, src_obj
, src_shndx
,
1103 dst_obj
, dst_shndx
, dst_off
);
1106 // Return the r_sym field from a relocation.
1107 // Most targets can use the default version of this routine,
1108 // but some targets have a non-standard r_info field, and will
1109 // need to provide a target-specific version.
1110 virtual unsigned int
1111 get_r_sym(const unsigned char* preloc
) const
1113 // Since REL and RELA relocs share the same structure through
1114 // the r_info field, we can just use REL here.
1115 elfcpp::Rel
<size
, big_endian
> rel(preloc
);
1116 return elfcpp::elf_r_sym
<size
>(rel
.get_r_info());
1120 Sized_target(const Target::Target_info
* pti
)
1123 gold_assert(pti
->size
== size
);
1124 gold_assert(pti
->is_big_endian
? big_endian
: !big_endian
);
1127 // Set the EI_OSABI field if requested.
1129 do_adjust_elf_header(unsigned char*, int);
1131 // Handle target specific gc actions when adding a gc reference.
1133 do_gc_add_reference(Symbol_table
*, Relobj
*, unsigned int,
1134 Relobj
*, unsigned int,
1135 typename
elfcpp::Elf_types
<size
>::Elf_Addr
) const
1139 do_function_location(Symbol_location
*) const
1143 } // End namespace gold.
1145 #endif // !defined(GOLD_TARGET_H)