1 // symtab.h -- the gold symbol table -*- C++ -*-
3 // Copyright 2006, 2007, 2008 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.
31 #include "parameters.h"
32 #include "stringpool.h"
44 template<int size
, bool big_endian
>
47 template<int size
, bool big_endian
>
50 class Version_script_info
;
56 class Output_symtab_xindex
;
58 // The base class of an entry in the symbol table. The symbol table
59 // can have a lot of entries, so we don't want this class to big.
60 // Size dependent fields can be found in the template class
61 // Sized_symbol. Targets may support their own derived classes.
66 // Because we want the class to be small, we don't use any virtual
67 // functions. But because symbols can be defined in different
68 // places, we need to classify them. This enum is the different
69 // sources of symbols we support.
72 // Symbol defined in a relocatable or dynamic input file--this is
73 // the most common case.
75 // Symbol defined in an Output_data, a special section created by
78 // Symbol defined in an Output_segment, with no associated
81 // Symbol value is constant.
83 // Symbol is undefined.
87 // When the source is IN_OUTPUT_SEGMENT, we need to describe what
89 enum Segment_offset_base
91 // From the start of the segment.
93 // From the end of the segment.
95 // From the filesz of the segment--i.e., after the loaded bytes
96 // but before the bytes which are allocated but zeroed.
100 // Return the symbol name.
103 { return this->name_
; }
105 // Return the (ANSI) demangled version of the name, if
106 // parameters.demangle() is true. Otherwise, return the name. This
107 // is intended to be used only for logging errors, so it's not
110 demangled_name() const;
112 // Return the symbol version. This will return NULL for an
113 // unversioned symbol.
116 { return this->version_
; }
118 // Return whether this version is the default for this symbol name
119 // (eg, "foo@@V2" is a default version; "foo@V1" is not). Only
120 // meaningful for versioned symbols.
124 gold_assert(this->version_
!= NULL
);
125 return this->is_def_
;
128 // Set that this version is the default for this symbol name.
131 { this->is_def_
= true; }
133 // Return the symbol source.
136 { return this->source_
; }
138 // Return the object with which this symbol is associated.
142 gold_assert(this->source_
== FROM_OBJECT
);
143 return this->u_
.from_object
.object
;
146 // Return the index of the section in the input relocatable or
147 // dynamic object file.
149 shndx(bool* is_ordinary
) const
151 gold_assert(this->source_
== FROM_OBJECT
);
152 *is_ordinary
= this->is_ordinary_shndx_
;
153 return this->u_
.from_object
.shndx
;
156 // Return the output data section with which this symbol is
157 // associated, if the symbol was specially defined with respect to
158 // an output data section.
162 gold_assert(this->source_
== IN_OUTPUT_DATA
);
163 return this->u_
.in_output_data
.output_data
;
166 // If this symbol was defined with respect to an output data
167 // section, return whether the value is an offset from end.
169 offset_is_from_end() const
171 gold_assert(this->source_
== IN_OUTPUT_DATA
);
172 return this->u_
.in_output_data
.offset_is_from_end
;
175 // Return the output segment with which this symbol is associated,
176 // if the symbol was specially defined with respect to an output
179 output_segment() const
181 gold_assert(this->source_
== IN_OUTPUT_SEGMENT
);
182 return this->u_
.in_output_segment
.output_segment
;
185 // If this symbol was defined with respect to an output segment,
186 // return the offset base.
190 gold_assert(this->source_
== IN_OUTPUT_SEGMENT
);
191 return this->u_
.in_output_segment
.offset_base
;
194 // Return the symbol binding.
197 { return this->binding_
; }
199 // Return the symbol type.
202 { return this->type_
; }
204 // Return the symbol visibility.
207 { return this->visibility_
; }
209 // Return the non-visibility part of the st_other field.
212 { return this->nonvis_
; }
214 // Return whether this symbol is a forwarder. This will never be
215 // true of a symbol found in the hash table, but may be true of
216 // symbol pointers attached to object files.
219 { return this->is_forwarder_
; }
221 // Mark this symbol as a forwarder.
224 { this->is_forwarder_
= true; }
226 // Return whether this symbol has an alias in the weak aliases table
230 { return this->has_alias_
; }
232 // Mark this symbol as having an alias.
235 { this->has_alias_
= true; }
237 // Return whether this symbol needs an entry in the dynamic symbol
240 needs_dynsym_entry() const
242 return (this->needs_dynsym_entry_
243 || (this->in_reg() && this->in_dyn()));
246 // Mark this symbol as needing an entry in the dynamic symbol table.
248 set_needs_dynsym_entry()
249 { this->needs_dynsym_entry_
= true; }
251 // Return whether this symbol should be added to the dynamic symbol
254 should_add_dynsym_entry() const;
256 // Return whether this symbol has been seen in a regular object.
259 { return this->in_reg_
; }
261 // Mark this symbol as having been seen in a regular object.
264 { this->in_reg_
= true; }
266 // Return whether this symbol has been seen in a dynamic object.
269 { return this->in_dyn_
; }
271 // Mark this symbol as having been seen in a dynamic object.
274 { this->in_dyn_
= true; }
276 // Return the index of this symbol in the output file symbol table.
277 // A value of -1U means that this symbol is not going into the
278 // output file. This starts out as zero, and is set to a non-zero
279 // value by Symbol_table::finalize. It is an error to ask for the
280 // symbol table index before it has been set.
284 gold_assert(this->symtab_index_
!= 0);
285 return this->symtab_index_
;
288 // Set the index of the symbol in the output file symbol table.
290 set_symtab_index(unsigned int index
)
292 gold_assert(index
!= 0);
293 this->symtab_index_
= index
;
296 // Return whether this symbol already has an index in the output
297 // file symbol table.
299 has_symtab_index() const
300 { return this->symtab_index_
!= 0; }
302 // Return the index of this symbol in the dynamic symbol table. A
303 // value of -1U means that this symbol is not going into the dynamic
304 // symbol table. This starts out as zero, and is set to a non-zero
305 // during Layout::finalize. It is an error to ask for the dynamic
306 // symbol table index before it has been set.
310 gold_assert(this->dynsym_index_
!= 0);
311 return this->dynsym_index_
;
314 // Set the index of the symbol in the dynamic symbol table.
316 set_dynsym_index(unsigned int index
)
318 gold_assert(index
!= 0);
319 this->dynsym_index_
= index
;
322 // Return whether this symbol already has an index in the dynamic
325 has_dynsym_index() const
326 { return this->dynsym_index_
!= 0; }
328 // Return whether this symbol has an entry in the GOT section.
329 // For a TLS symbol, this GOT entry will hold its tp-relative offset.
331 has_got_offset(unsigned int got_type
) const
332 { return this->got_offsets_
.get_offset(got_type
) != -1U; }
334 // Return the offset into the GOT section of this symbol.
336 got_offset(unsigned int got_type
) const
338 unsigned int got_offset
= this->got_offsets_
.get_offset(got_type
);
339 gold_assert(got_offset
!= -1U);
343 // Set the GOT offset of this symbol.
345 set_got_offset(unsigned int got_type
, unsigned int got_offset
)
346 { this->got_offsets_
.set_offset(got_type
, got_offset
); }
348 // Return whether this symbol has an entry in the PLT section.
350 has_plt_offset() const
351 { return this->has_plt_offset_
; }
353 // Return the offset into the PLT section of this symbol.
357 gold_assert(this->has_plt_offset());
358 return this->plt_offset_
;
361 // Set the PLT offset of this symbol.
363 set_plt_offset(unsigned int plt_offset
)
365 this->has_plt_offset_
= true;
366 this->plt_offset_
= plt_offset
;
369 // Return whether this dynamic symbol needs a special value in the
370 // dynamic symbol table.
372 needs_dynsym_value() const
373 { return this->needs_dynsym_value_
; }
375 // Set that this dynamic symbol needs a special value in the dynamic
378 set_needs_dynsym_value()
380 gold_assert(this->object()->is_dynamic());
381 this->needs_dynsym_value_
= true;
384 // Return true if the final value of this symbol is known at link
387 final_value_is_known() const;
389 // Return whether this is a defined symbol (not undefined or
395 if (this->source_
!= FROM_OBJECT
)
396 return this->source_
!= IS_UNDEFINED
;
397 unsigned int shndx
= this->shndx(&is_ordinary
);
399 ? shndx
!= elfcpp::SHN_UNDEF
400 : shndx
!= elfcpp::SHN_COMMON
);
403 // Return true if this symbol is from a dynamic object.
405 is_from_dynobj() const
407 return this->source_
== FROM_OBJECT
&& this->object()->is_dynamic();
410 // Return whether this is an undefined symbol.
415 return ((this->source_
== FROM_OBJECT
416 && this->shndx(&is_ordinary
) == elfcpp::SHN_UNDEF
418 || this->source_
== IS_UNDEFINED
);
421 // Return whether this is a weak undefined symbol.
423 is_weak_undefined() const
424 { return this->is_undefined() && this->binding() == elfcpp::STB_WEAK
; }
426 // Return whether this is an absolute symbol.
431 return ((this->source_
== FROM_OBJECT
432 && this->shndx(&is_ordinary
) == elfcpp::SHN_ABS
434 || this->source_
== IS_CONSTANT
);
437 // Return whether this is a common symbol.
442 return (this->source_
== FROM_OBJECT
443 && ((this->shndx(&is_ordinary
) == elfcpp::SHN_COMMON
445 || this->type_
== elfcpp::STT_COMMON
));
448 // Return whether this symbol can be seen outside this object.
450 is_externally_visible() const
452 return (this->visibility_
== elfcpp::STV_DEFAULT
453 || this->visibility_
== elfcpp::STV_PROTECTED
);
456 // Return true if this symbol can be preempted by a definition in
457 // another link unit.
459 is_preemptible() const
461 // It doesn't make sense to ask whether a symbol defined in
462 // another object is preemptible.
463 gold_assert(!this->is_from_dynobj());
465 // It doesn't make sense to ask whether an undefined symbol
467 gold_assert(!this->is_undefined());
469 // If a symbol does not have default visibility, it can not be
470 // seen outside this link unit and therefore is not preemptible.
471 if (this->visibility_
!= elfcpp::STV_DEFAULT
)
474 // If this symbol has been forced to be a local symbol by a
475 // version script, then it is not visible outside this link unit
476 // and is not preemptible.
477 if (this->is_forced_local_
)
480 // If we are not producing a shared library, then nothing is
482 if (!parameters
->options().shared())
485 // If the user used -Bsymbolic, then nothing is preemptible.
486 if (parameters
->options().Bsymbolic())
489 // If the user used -Bsymbolic-functions, then functions are not
490 // preemptible. We explicitly check for not being STT_OBJECT,
491 // rather than for being STT_FUNC, because that is what the GNU
493 if (this->type() != elfcpp::STT_OBJECT
494 && parameters
->options().Bsymbolic_functions())
497 // Otherwise the symbol is preemptible.
501 // Return true if this symbol is a function that needs a PLT entry.
502 // If the symbol is defined in a dynamic object or if it is subject
503 // to pre-emption, we need to make a PLT entry. If we're doing a
504 // static link, we don't create PLT entries.
506 needs_plt_entry() const
508 return (!parameters
->doing_static_link()
509 && this->type() == elfcpp::STT_FUNC
510 && (this->is_from_dynobj()
511 || this->is_undefined()
512 || this->is_preemptible()));
515 // When determining whether a reference to a symbol needs a dynamic
516 // relocation, we need to know several things about the reference.
517 // These flags may be or'ed together.
520 // Reference to the symbol's absolute address.
522 // A non-PIC reference.
528 // Given a direct absolute or pc-relative static relocation against
529 // the global symbol, this function returns whether a dynamic relocation
533 needs_dynamic_reloc(int flags
) const
535 // No dynamic relocations in a static link!
536 if (parameters
->doing_static_link())
539 // A reference to a weak undefined symbol from an executable should be
540 // statically resolved to 0, and does not need a dynamic relocation.
541 // This matches gnu ld behavior.
542 if (this->is_weak_undefined() && !parameters
->options().shared())
545 // A reference to an absolute symbol does not need a dynamic relocation.
546 if (this->is_absolute())
549 // An absolute reference within a position-independent output file
550 // will need a dynamic relocation.
551 if ((flags
& ABSOLUTE_REF
)
552 && parameters
->options().output_is_position_independent())
555 // A function call that can branch to a local PLT entry does not need
556 // a dynamic relocation. A non-pic pc-relative function call in a
557 // shared library cannot use a PLT entry.
558 if ((flags
& FUNCTION_CALL
)
559 && this->has_plt_offset()
560 && !((flags
& NON_PIC_REF
) && parameters
->options().shared()))
563 // A reference to any PLT entry in a non-position-independent executable
564 // does not need a dynamic relocation.
565 if (!parameters
->options().output_is_position_independent()
566 && this->has_plt_offset())
569 // A reference to a symbol defined in a dynamic object or to a
570 // symbol that is preemptible will need a dynamic relocation.
571 if (this->is_from_dynobj()
572 || this->is_undefined()
573 || this->is_preemptible())
576 // For all other cases, return FALSE.
580 // Whether we should use the PLT offset associated with a symbol for
581 // a relocation. IS_NON_PIC_REFERENCE is true if this is a non-PIC
582 // reloc--the same set of relocs for which we would pass NON_PIC_REF
583 // to the needs_dynamic_reloc function.
586 use_plt_offset(bool is_non_pic_reference
) const
588 // If the symbol doesn't have a PLT offset, then naturally we
589 // don't want to use it.
590 if (!this->has_plt_offset())
593 // If we are going to generate a dynamic relocation, then we will
594 // wind up using that, so no need to use the PLT entry.
595 if (this->needs_dynamic_reloc(FUNCTION_CALL
596 | (is_non_pic_reference
601 // If the symbol is from a dynamic object, we need to use the PLT
603 if (this->is_from_dynobj())
606 // If we are generating a shared object, and this symbol is
607 // undefined or preemptible, we need to use the PLT entry.
608 if (parameters
->options().shared()
609 && (this->is_undefined() || this->is_preemptible()))
612 // If this is a weak undefined symbol, we need to use the PLT
613 // entry; the symbol may be defined by a library loaded at
615 if (this->is_weak_undefined())
618 // Otherwise we can use the regular definition.
622 // Given a direct absolute static relocation against
623 // the global symbol, where a dynamic relocation is needed, this
624 // function returns whether a relative dynamic relocation can be used.
625 // The caller must determine separately whether the static relocation
626 // is compatible with a relative relocation.
629 can_use_relative_reloc(bool is_function_call
) const
631 // A function call that can branch to a local PLT entry can
632 // use a RELATIVE relocation.
633 if (is_function_call
&& this->has_plt_offset())
636 // A reference to a symbol defined in a dynamic object or to a
637 // symbol that is preemptible can not use a RELATIVE relocaiton.
638 if (this->is_from_dynobj()
639 || this->is_undefined()
640 || this->is_preemptible())
643 // For all other cases, return TRUE.
647 // Return the output section where this symbol is defined. Return
648 // NULL if the symbol has an absolute value.
650 output_section() const;
652 // Set the symbol's output section. This is used for symbols
653 // defined in scripts. This should only be called after the symbol
654 // table has been finalized.
656 set_output_section(Output_section
*);
658 // Return whether there should be a warning for references to this
662 { return this->has_warning_
; }
664 // Mark this symbol as having a warning.
667 { this->has_warning_
= true; }
669 // Return whether this symbol is defined by a COPY reloc from a
672 is_copied_from_dynobj() const
673 { return this->is_copied_from_dynobj_
; }
675 // Mark this symbol as defined by a COPY reloc.
677 set_is_copied_from_dynobj()
678 { this->is_copied_from_dynobj_
= true; }
680 // Return whether this symbol is forced to visibility STB_LOCAL
681 // by a "local:" entry in a version script.
683 is_forced_local() const
684 { return this->is_forced_local_
; }
686 // Mark this symbol as forced to STB_LOCAL visibility.
688 set_is_forced_local()
689 { this->is_forced_local_
= true; }
692 // Instances of this class should always be created at a specific
695 { memset(this, 0, sizeof *this); }
697 // Initialize the general fields.
699 init_fields(const char* name
, const char* version
,
700 elfcpp::STT type
, elfcpp::STB binding
,
701 elfcpp::STV visibility
, unsigned char nonvis
);
703 // Initialize fields from an ELF symbol in OBJECT. ST_SHNDX is the
704 // section index, IS_ORDINARY is whether it is a normal section
705 // index rather than a special code.
706 template<int size
, bool big_endian
>
708 init_base_object(const char *name
, const char* version
, Object
* object
,
709 const elfcpp::Sym
<size
, big_endian
>&, unsigned int st_shndx
,
712 // Initialize fields for an Output_data.
714 init_base_output_data(const char* name
, const char* version
, Output_data
*,
715 elfcpp::STT
, elfcpp::STB
, elfcpp::STV
,
716 unsigned char nonvis
, bool offset_is_from_end
);
718 // Initialize fields for an Output_segment.
720 init_base_output_segment(const char* name
, const char* version
,
721 Output_segment
* os
, elfcpp::STT type
,
722 elfcpp::STB binding
, elfcpp::STV visibility
,
723 unsigned char nonvis
,
724 Segment_offset_base offset_base
);
726 // Initialize fields for a constant.
728 init_base_constant(const char* name
, const char* version
, elfcpp::STT type
,
729 elfcpp::STB binding
, elfcpp::STV visibility
,
730 unsigned char nonvis
);
732 // Initialize fields for an undefined symbol.
734 init_base_undefined(const char* name
, const char* version
, elfcpp::STT type
,
735 elfcpp::STB binding
, elfcpp::STV visibility
,
736 unsigned char nonvis
);
738 // Override existing symbol.
739 template<int size
, bool big_endian
>
741 override_base(const elfcpp::Sym
<size
, big_endian
>&, unsigned int st_shndx
,
742 bool is_ordinary
, Object
* object
, const char* version
);
744 // Override existing symbol with a special symbol.
746 override_base_with_special(const Symbol
* from
);
748 // Override symbol version.
750 override_version(const char* version
);
752 // Allocate a common symbol by giving it a location in the output
755 allocate_base_common(Output_data
*);
758 Symbol(const Symbol
&);
759 Symbol
& operator=(const Symbol
&);
761 // Symbol name (expected to point into a Stringpool).
763 // Symbol version (expected to point into a Stringpool). This may
765 const char* version_
;
769 // This struct is used if SOURCE_ == FROM_OBJECT.
772 // Object in which symbol is defined, or in which it was first
775 // Section number in object_ in which symbol is defined.
779 // This struct is used if SOURCE_ == IN_OUTPUT_DATA.
782 // Output_data in which symbol is defined. Before
783 // Layout::finalize the symbol's value is an offset within the
785 Output_data
* output_data
;
786 // True if the offset is from the end, false if the offset is
787 // from the beginning.
788 bool offset_is_from_end
;
791 // This struct is used if SOURCE_ == IN_OUTPUT_SEGMENT.
794 // Output_segment in which the symbol is defined. Before
795 // Layout::finalize the symbol's value is an offset.
796 Output_segment
* output_segment
;
797 // The base to use for the offset before Layout::finalize.
798 Segment_offset_base offset_base
;
802 // The index of this symbol in the output file. If the symbol is
803 // not going into the output file, this value is -1U. This field
804 // starts as always holding zero. It is set to a non-zero value by
805 // Symbol_table::finalize.
806 unsigned int symtab_index_
;
808 // The index of this symbol in the dynamic symbol table. If the
809 // symbol is not going into the dynamic symbol table, this value is
810 // -1U. This field starts as always holding zero. It is set to a
811 // non-zero value during Layout::finalize.
812 unsigned int dynsym_index_
;
814 // If this symbol has an entry in the GOT section (has_got_offset_
815 // is true), this holds the offset from the start of the GOT section.
816 // A symbol may have more than one GOT offset (e.g., when mixing
817 // modules compiled with two different TLS models), but will usually
819 Got_offset_list got_offsets_
;
821 // If this symbol has an entry in the PLT section (has_plt_offset_
822 // is true), then this is the offset from the start of the PLT
824 unsigned int plt_offset_
;
826 // Symbol type (bits 0 to 3).
827 elfcpp::STT type_
: 4;
828 // Symbol binding (bits 4 to 7).
829 elfcpp::STB binding_
: 4;
830 // Symbol visibility (bits 8 to 9).
831 elfcpp::STV visibility_
: 2;
832 // Rest of symbol st_other field (bits 10 to 15).
833 unsigned int nonvis_
: 6;
834 // The type of symbol (bits 16 to 18).
836 // True if this symbol always requires special target-specific
837 // handling (bit 19).
838 bool is_target_special_
: 1;
839 // True if this is the default version of the symbol (bit 20).
841 // True if this symbol really forwards to another symbol. This is
842 // used when we discover after the fact that two different entries
843 // in the hash table really refer to the same symbol. This will
844 // never be set for a symbol found in the hash table, but may be set
845 // for a symbol found in the list of symbols attached to an Object.
846 // It forwards to the symbol found in the forwarders_ map of
847 // Symbol_table (bit 21).
848 bool is_forwarder_
: 1;
849 // True if the symbol has an alias in the weak_aliases table in
850 // Symbol_table (bit 22).
852 // True if this symbol needs to be in the dynamic symbol table (bit
854 bool needs_dynsym_entry_
: 1;
855 // True if we've seen this symbol in a regular object (bit 24).
857 // True if we've seen this symbol in a dynamic object (bit 25).
859 // True if the symbol has an entry in the PLT section (bit 26).
860 bool has_plt_offset_
: 1;
861 // True if this is a dynamic symbol which needs a special value in
862 // the dynamic symbol table (bit 27).
863 bool needs_dynsym_value_
: 1;
864 // True if there is a warning for this symbol (bit 28).
865 bool has_warning_
: 1;
866 // True if we are using a COPY reloc for this symbol, so that the
867 // real definition lives in a dynamic object (bit 29).
868 bool is_copied_from_dynobj_
: 1;
869 // True if this symbol was forced to local visibility by a version
871 bool is_forced_local_
: 1;
872 // True if the field u_.from_object.shndx is an ordinary section
873 // index, not one of the special codes from SHN_LORESERVE to
875 bool is_ordinary_shndx_
: 1;
878 // The parts of a symbol which are size specific. Using a template
879 // derived class like this helps us use less space on a 32-bit system.
882 class Sized_symbol
: public Symbol
885 typedef typename
elfcpp::Elf_types
<size
>::Elf_Addr Value_type
;
886 typedef typename
elfcpp::Elf_types
<size
>::Elf_WXword Size_type
;
891 // Initialize fields from an ELF symbol in OBJECT. ST_SHNDX is the
892 // section index, IS_ORDINARY is whether it is a normal section
893 // index rather than a special code.
894 template<bool big_endian
>
896 init_object(const char *name
, const char* version
, Object
* object
,
897 const elfcpp::Sym
<size
, big_endian
>&, unsigned int st_shndx
,
900 // Initialize fields for an Output_data.
902 init_output_data(const char* name
, const char* version
, Output_data
*,
903 Value_type value
, Size_type symsize
, elfcpp::STT
,
904 elfcpp::STB
, elfcpp::STV
, unsigned char nonvis
,
905 bool offset_is_from_end
);
907 // Initialize fields for an Output_segment.
909 init_output_segment(const char* name
, const char* version
, Output_segment
*,
910 Value_type value
, Size_type symsize
, elfcpp::STT
,
911 elfcpp::STB
, elfcpp::STV
, unsigned char nonvis
,
912 Segment_offset_base offset_base
);
914 // Initialize fields for a constant.
916 init_constant(const char* name
, const char* version
, Value_type value
,
917 Size_type symsize
, elfcpp::STT
, elfcpp::STB
, elfcpp::STV
,
918 unsigned char nonvis
);
920 // Initialize fields for an undefined symbol.
922 init_undefined(const char* name
, const char* version
, elfcpp::STT
,
923 elfcpp::STB
, elfcpp::STV
, unsigned char nonvis
);
925 // Override existing symbol.
926 template<bool big_endian
>
928 override(const elfcpp::Sym
<size
, big_endian
>&, unsigned int st_shndx
,
929 bool is_ordinary
, Object
* object
, const char* version
);
931 // Override existing symbol with a special symbol.
933 override_with_special(const Sized_symbol
<size
>*);
935 // Return the symbol's value.
938 { return this->value_
; }
940 // Return the symbol's size (we can't call this 'size' because that
941 // is a template parameter).
944 { return this->symsize_
; }
946 // Set the symbol size. This is used when resolving common symbols.
948 set_symsize(Size_type symsize
)
949 { this->symsize_
= symsize
; }
951 // Set the symbol value. This is called when we store the final
952 // values of the symbols into the symbol table.
954 set_value(Value_type value
)
955 { this->value_
= value
; }
957 // Allocate a common symbol by giving it a location in the output
960 allocate_common(Output_data
*, Value_type value
);
963 Sized_symbol(const Sized_symbol
&);
964 Sized_symbol
& operator=(const Sized_symbol
&);
966 // Symbol value. Before Layout::finalize this is the offset in the
967 // input section. This is set to the final value during
974 // A struct describing a symbol defined by the linker, where the value
975 // of the symbol is defined based on an output section. This is used
976 // for symbols defined by the linker, like "_init_array_start".
978 struct Define_symbol_in_section
982 // The name of the output section with which this symbol should be
983 // associated. If there is no output section with that name, the
984 // symbol will be defined as zero.
985 const char* output_section
;
986 // The offset of the symbol within the output section. This is an
987 // offset from the start of the output section, unless start_at_end
988 // is true, in which case this is an offset from the end of the
991 // The size of the symbol.
995 // The symbol binding.
997 // The symbol visibility.
998 elfcpp::STV visibility
;
999 // The rest of the st_other field.
1000 unsigned char nonvis
;
1001 // If true, the value field is an offset from the end of the output
1003 bool offset_is_from_end
;
1004 // If true, this symbol is defined only if we see a reference to it.
1008 // A struct describing a symbol defined by the linker, where the value
1009 // of the symbol is defined based on a segment. This is used for
1010 // symbols defined by the linker, like "_end". We describe the
1011 // segment with which the symbol should be associated by its
1012 // characteristics. If no segment meets these characteristics, the
1013 // symbol will be defined as zero. If there is more than one segment
1014 // which meets these characteristics, we will use the first one.
1016 struct Define_symbol_in_segment
1020 // The segment type where the symbol should be defined, typically
1022 elfcpp::PT segment_type
;
1023 // Bitmask of segment flags which must be set.
1024 elfcpp::PF segment_flags_set
;
1025 // Bitmask of segment flags which must be clear.
1026 elfcpp::PF segment_flags_clear
;
1027 // The offset of the symbol within the segment. The offset is
1028 // calculated from the position set by offset_base.
1030 // The size of the symbol.
1034 // The symbol binding.
1035 elfcpp::STB binding
;
1036 // The symbol visibility.
1037 elfcpp::STV visibility
;
1038 // The rest of the st_other field.
1039 unsigned char nonvis
;
1040 // The base from which we compute the offset.
1041 Symbol::Segment_offset_base offset_base
;
1042 // If true, this symbol is defined only if we see a reference to it.
1046 // This class manages warnings. Warnings are a GNU extension. When
1047 // we see a section named .gnu.warning.SYM in an object file, and if
1048 // we wind using the definition of SYM from that object file, then we
1049 // will issue a warning for any relocation against SYM from a
1050 // different object file. The text of the warning is the contents of
1051 // the section. This is not precisely the definition used by the old
1052 // GNU linker; the old GNU linker treated an occurrence of
1053 // .gnu.warning.SYM as defining a warning symbol. A warning symbol
1054 // would trigger a warning on any reference. However, it was
1055 // inconsistent in that a warning in a dynamic object only triggered
1056 // if there was no definition in a regular object. This linker is
1057 // different in that we only issue a warning if we use the symbol
1058 // definition from the same object file as the warning section.
1067 // Add a warning for symbol NAME in object OBJ. WARNING is the text
1070 add_warning(Symbol_table
* symtab
, const char* name
, Object
* obj
,
1071 const std::string
& warning
);
1073 // For each symbol for which we should give a warning, make a note
1076 note_warnings(Symbol_table
* symtab
);
1078 // Issue a warning for a reference to SYM at RELINFO's location.
1079 template<int size
, bool big_endian
>
1081 issue_warning(const Symbol
* sym
, const Relocate_info
<size
, big_endian
>*,
1082 size_t relnum
, off_t reloffset
) const;
1085 Warnings(const Warnings
&);
1086 Warnings
& operator=(const Warnings
&);
1088 // What we need to know to get the warning text.
1089 struct Warning_location
1091 // The object the warning is in.
1093 // The warning text.
1097 : object(NULL
), text()
1101 set(Object
* o
, const std::string
& t
)
1108 // A mapping from warning symbol names (canonicalized in
1109 // Symbol_table's namepool_ field) to warning information.
1110 typedef Unordered_map
<const char*, Warning_location
> Warning_table
;
1112 Warning_table warnings_
;
1115 // The main linker symbol table.
1120 // COUNT is an estimate of how many symbosl will be inserted in the
1121 // symbol table. It's ok to put 0 if you don't know; a correct
1122 // guess will just save some CPU by reducing hashtable resizes.
1123 Symbol_table(unsigned int count
, const Version_script_info
& version_script
);
1127 // Add COUNT external symbols from the relocatable object RELOBJ to
1128 // the symbol table. SYMS is the symbols, SYMNDX_OFFSET is the
1129 // offset in the symbol table of the first symbol, SYM_NAMES is
1130 // their names, SYM_NAME_SIZE is the size of SYM_NAMES. This sets
1131 // SYMPOINTERS to point to the symbols in the symbol table. It sets
1132 // *DEFINED to the number of defined symbols.
1133 template<int size
, bool big_endian
>
1135 add_from_relobj(Sized_relobj
<size
, big_endian
>* relobj
,
1136 const unsigned char* syms
, size_t count
,
1137 size_t symndx_offset
, const char* sym_names
,
1138 size_t sym_name_size
,
1139 typename Sized_relobj
<size
, big_endian
>::Symbols
*,
1142 // Add COUNT dynamic symbols from the dynamic object DYNOBJ to the
1143 // symbol table. SYMS is the symbols. SYM_NAMES is their names.
1144 // SYM_NAME_SIZE is the size of SYM_NAMES. The other parameters are
1145 // symbol version data.
1146 template<int size
, bool big_endian
>
1148 add_from_dynobj(Sized_dynobj
<size
, big_endian
>* dynobj
,
1149 const unsigned char* syms
, size_t count
,
1150 const char* sym_names
, size_t sym_name_size
,
1151 const unsigned char* versym
, size_t versym_size
,
1152 const std::vector
<const char*>*,
1153 typename Sized_relobj
<size
, big_endian
>::Symbols
*,
1156 // Define a special symbol based on an Output_data. It is a
1157 // multiple definition error if this symbol is already defined.
1159 define_in_output_data(const char* name
, const char* version
,
1160 Output_data
*, uint64_t value
, uint64_t symsize
,
1161 elfcpp::STT type
, elfcpp::STB binding
,
1162 elfcpp::STV visibility
, unsigned char nonvis
,
1163 bool offset_is_from_end
, bool only_if_ref
);
1165 // Define a special symbol based on an Output_segment. It is a
1166 // multiple definition error if this symbol is already defined.
1168 define_in_output_segment(const char* name
, const char* version
,
1169 Output_segment
*, uint64_t value
, uint64_t symsize
,
1170 elfcpp::STT type
, elfcpp::STB binding
,
1171 elfcpp::STV visibility
, unsigned char nonvis
,
1172 Symbol::Segment_offset_base
, bool only_if_ref
);
1174 // Define a special symbol with a constant value. It is a multiple
1175 // definition error if this symbol is already defined.
1177 define_as_constant(const char* name
, const char* version
,
1178 uint64_t value
, uint64_t symsize
, elfcpp::STT type
,
1179 elfcpp::STB binding
, elfcpp::STV visibility
,
1180 unsigned char nonvis
, bool only_if_ref
,
1181 bool force_override
);
1183 // Define a set of symbols in output sections. If ONLY_IF_REF is
1184 // true, only define them if they are referenced.
1186 define_symbols(const Layout
*, int count
, const Define_symbol_in_section
*,
1189 // Define a set of symbols in output segments. If ONLY_IF_REF is
1190 // true, only defined them if they are referenced.
1192 define_symbols(const Layout
*, int count
, const Define_symbol_in_segment
*,
1195 // Define SYM using a COPY reloc. POSD is the Output_data where the
1196 // symbol should be defined--typically a .dyn.bss section. VALUE is
1197 // the offset within POSD.
1200 define_with_copy_reloc(Sized_symbol
<size
>* sym
, Output_data
* posd
,
1201 typename
elfcpp::Elf_types
<size
>::Elf_Addr
);
1203 // Look up a symbol.
1205 lookup(const char*, const char* version
= NULL
) const;
1207 // Return the real symbol associated with the forwarder symbol FROM.
1209 resolve_forwards(const Symbol
* from
) const;
1211 // Return the sized version of a symbol in this table.
1214 get_sized_symbol(Symbol
*) const;
1217 const Sized_symbol
<size
>*
1218 get_sized_symbol(const Symbol
*) const;
1220 // Return the count of undefined symbols seen.
1222 saw_undefined() const
1223 { return this->saw_undefined_
; }
1225 // Allocate the common symbols
1227 allocate_commons(Layout
*, Mapfile
*);
1229 // Add a warning for symbol NAME in object OBJ. WARNING is the text
1232 add_warning(const char* name
, Object
* obj
, const std::string
& warning
)
1233 { this->warnings_
.add_warning(this, name
, obj
, warning
); }
1235 // Canonicalize a symbol name for use in the hash table.
1237 canonicalize_name(const char* name
)
1238 { return this->namepool_
.add(name
, true, NULL
); }
1240 // Possibly issue a warning for a reference to SYM at LOCATION which
1242 template<int size
, bool big_endian
>
1244 issue_warning(const Symbol
* sym
,
1245 const Relocate_info
<size
, big_endian
>* relinfo
,
1246 size_t relnum
, off_t reloffset
) const
1247 { this->warnings_
.issue_warning(sym
, relinfo
, relnum
, reloffset
); }
1249 // Check candidate_odr_violations_ to find symbols with the same name
1250 // but apparently different definitions (different source-file/line-no).
1252 detect_odr_violations(const Task
*, const char* output_file_name
) const;
1254 // Add any undefined symbols named on the command line to the symbol
1257 add_undefined_symbols_from_command_line();
1259 // SYM is defined using a COPY reloc. Return the dynamic object
1260 // where the original definition was found.
1262 get_copy_source(const Symbol
* sym
) const;
1264 // Set the dynamic symbol indexes. INDEX is the index of the first
1265 // global dynamic symbol. Pointers to the symbols are stored into
1266 // the vector. The names are stored into the Stringpool. This
1267 // returns an updated dynamic symbol index.
1269 set_dynsym_indexes(unsigned int index
, std::vector
<Symbol
*>*,
1270 Stringpool
*, Versions
*);
1272 // Finalize the symbol table after we have set the final addresses
1273 // of all the input sections. This sets the final symbol indexes,
1274 // values and adds the names to *POOL. *PLOCAL_SYMCOUNT is the
1275 // index of the first global symbol. OFF is the file offset of the
1276 // global symbol table, DYNOFF is the offset of the globals in the
1277 // dynamic symbol table, DYN_GLOBAL_INDEX is the index of the first
1278 // global dynamic symbol, and DYNCOUNT is the number of global
1279 // dynamic symbols. This records the parameters, and returns the
1280 // new file offset. It updates *PLOCAL_SYMCOUNT if it created any
1283 finalize(off_t off
, off_t dynoff
, size_t dyn_global_index
, size_t dyncount
,
1284 Stringpool
* pool
, unsigned int *plocal_symcount
);
1286 // Write out the global symbols.
1288 write_globals(const Input_objects
*, const Stringpool
*, const Stringpool
*,
1289 Output_symtab_xindex
*, Output_symtab_xindex
*,
1290 Output_file
*) const;
1292 // Write out a section symbol. Return the updated offset.
1294 write_section_symbol(const Output_section
*, Output_symtab_xindex
*,
1295 Output_file
*, off_t
) const;
1297 // Dump statistical information to stderr.
1299 print_stats() const;
1301 // Return the version script information.
1302 const Version_script_info
&
1303 version_script() const
1304 { return version_script_
; }
1307 Symbol_table(const Symbol_table
&);
1308 Symbol_table
& operator=(const Symbol_table
&);
1310 // The type of the list of common symbols.
1311 typedef std::vector
<Symbol
*> Commons_type
;
1313 // Make FROM a forwarder symbol to TO.
1315 make_forwarder(Symbol
* from
, Symbol
* to
);
1318 template<int size
, bool big_endian
>
1320 add_from_object(Object
*, const char *name
, Stringpool::Key name_key
,
1321 const char *version
, Stringpool::Key version_key
,
1322 bool def
, const elfcpp::Sym
<size
, big_endian
>& sym
,
1323 unsigned int st_shndx
, bool is_ordinary
,
1324 unsigned int orig_st_shndx
);
1327 template<int size
, bool big_endian
>
1329 resolve(Sized_symbol
<size
>* to
,
1330 const elfcpp::Sym
<size
, big_endian
>& sym
,
1331 unsigned int st_shndx
, bool is_ordinary
,
1332 unsigned int orig_st_shndx
,
1333 Object
*, const char* version
);
1335 template<int size
, bool big_endian
>
1337 resolve(Sized_symbol
<size
>* to
, const Sized_symbol
<size
>* from
);
1339 // Record that a symbol is forced to be local by a version script.
1341 force_local(Symbol
*);
1343 // Adjust NAME and *NAME_KEY for wrapping.
1345 wrap_symbol(Object
* object
, const char*, Stringpool::Key
* name_key
);
1347 // Whether we should override a symbol, based on flags in
1350 should_override(const Symbol
*, unsigned int, Object
*, bool*);
1352 // Override a symbol.
1353 template<int size
, bool big_endian
>
1355 override(Sized_symbol
<size
>* tosym
,
1356 const elfcpp::Sym
<size
, big_endian
>& fromsym
,
1357 unsigned int st_shndx
, bool is_ordinary
,
1358 Object
* object
, const char* version
);
1360 // Whether we should override a symbol with a special symbol which
1361 // is automatically defined by the linker.
1363 should_override_with_special(const Symbol
*);
1365 // Override a symbol with a special symbol.
1368 override_with_special(Sized_symbol
<size
>* tosym
,
1369 const Sized_symbol
<size
>* fromsym
);
1371 // Record all weak alias sets for a dynamic object.
1374 record_weak_aliases(std::vector
<Sized_symbol
<size
>*>*);
1376 // Define a special symbol.
1377 template<int size
, bool big_endian
>
1379 define_special_symbol(const char** pname
, const char** pversion
,
1380 bool only_if_ref
, Sized_symbol
<size
>** poldsym
);
1382 // Define a symbol in an Output_data, sized version.
1385 do_define_in_output_data(const char* name
, const char* version
, Output_data
*,
1386 typename
elfcpp::Elf_types
<size
>::Elf_Addr value
,
1387 typename
elfcpp::Elf_types
<size
>::Elf_WXword ssize
,
1388 elfcpp::STT type
, elfcpp::STB binding
,
1389 elfcpp::STV visibility
, unsigned char nonvis
,
1390 bool offset_is_from_end
, bool only_if_ref
);
1392 // Define a symbol in an Output_segment, sized version.
1395 do_define_in_output_segment(
1396 const char* name
, const char* version
, Output_segment
* os
,
1397 typename
elfcpp::Elf_types
<size
>::Elf_Addr value
,
1398 typename
elfcpp::Elf_types
<size
>::Elf_WXword ssize
,
1399 elfcpp::STT type
, elfcpp::STB binding
,
1400 elfcpp::STV visibility
, unsigned char nonvis
,
1401 Symbol::Segment_offset_base offset_base
, bool only_if_ref
);
1403 // Define a symbol as a constant, sized version.
1406 do_define_as_constant(
1407 const char* name
, const char* version
,
1408 typename
elfcpp::Elf_types
<size
>::Elf_Addr value
,
1409 typename
elfcpp::Elf_types
<size
>::Elf_WXword ssize
,
1410 elfcpp::STT type
, elfcpp::STB binding
,
1411 elfcpp::STV visibility
, unsigned char nonvis
,
1412 bool only_if_ref
, bool force_override
);
1414 // Add any undefined symbols named on the command line to the symbol
1415 // table, sized version.
1418 do_add_undefined_symbols_from_command_line();
1420 // Allocate the common symbols, sized version.
1423 do_allocate_commons(Layout
*, Mapfile
*);
1425 // Allocate the common symbols from one list.
1428 do_allocate_commons_list(Layout
*, bool is_tls
, Commons_type
*, Mapfile
*);
1430 // Implement detect_odr_violations.
1431 template<int size
, bool big_endian
>
1433 sized_detect_odr_violations() const;
1435 // Finalize symbols specialized for size.
1438 sized_finalize(off_t
, Stringpool
*, unsigned int*);
1440 // Finalize a symbol. Return whether it should be added to the
1444 sized_finalize_symbol(Symbol
*);
1446 // Add a symbol the final symtab by setting its index.
1449 add_to_final_symtab(Symbol
*, Stringpool
*, unsigned int* pindex
, off_t
* poff
);
1451 // Write globals specialized for size and endianness.
1452 template<int size
, bool big_endian
>
1454 sized_write_globals(const Input_objects
*, const Stringpool
*,
1455 const Stringpool
*, Output_symtab_xindex
*,
1456 Output_symtab_xindex
*, Output_file
*) const;
1458 // Write out a symbol to P.
1459 template<int size
, bool big_endian
>
1461 sized_write_symbol(Sized_symbol
<size
>*,
1462 typename
elfcpp::Elf_types
<size
>::Elf_Addr value
,
1464 const Stringpool
*, unsigned char* p
) const;
1466 // Possibly warn about an undefined symbol from a dynamic object.
1468 warn_about_undefined_dynobj_symbol(const Input_objects
*, Symbol
*) const;
1470 // Write out a section symbol, specialized for size and endianness.
1471 template<int size
, bool big_endian
>
1473 sized_write_section_symbol(const Output_section
*, Output_symtab_xindex
*,
1474 Output_file
*, off_t
) const;
1476 // The type of the symbol hash table.
1478 typedef std::pair
<Stringpool::Key
, Stringpool::Key
> Symbol_table_key
;
1480 struct Symbol_table_hash
1483 operator()(const Symbol_table_key
&) const;
1486 struct Symbol_table_eq
1489 operator()(const Symbol_table_key
&, const Symbol_table_key
&) const;
1492 typedef Unordered_map
<Symbol_table_key
, Symbol
*, Symbol_table_hash
,
1493 Symbol_table_eq
> Symbol_table_type
;
1495 // The type of the list of symbols which have been forced local.
1496 typedef std::vector
<Symbol
*> Forced_locals
;
1498 // A map from symbols with COPY relocs to the dynamic objects where
1499 // they are defined.
1500 typedef Unordered_map
<const Symbol
*, Dynobj
*> Copied_symbol_dynobjs
;
1502 // A map from symbol name (as a pointer into the namepool) to all
1503 // the locations the symbols is (weakly) defined (and certain other
1504 // conditions are met). This map will be used later to detect
1505 // possible One Definition Rule (ODR) violations.
1506 struct Symbol_location
1508 Object
* object
; // Object where the symbol is defined.
1509 unsigned int shndx
; // Section-in-object where the symbol is defined.
1510 off_t offset
; // Offset-in-section where the symbol is defined.
1511 bool operator==(const Symbol_location
& that
) const
1513 return (this->object
== that
.object
1514 && this->shndx
== that
.shndx
1515 && this->offset
== that
.offset
);
1519 struct Symbol_location_hash
1521 size_t operator()(const Symbol_location
& loc
) const
1522 { return reinterpret_cast<uintptr_t>(loc
.object
) ^ loc
.offset
^ loc
.shndx
; }
1525 typedef Unordered_map
<const char*,
1526 Unordered_set
<Symbol_location
, Symbol_location_hash
> >
1529 // We increment this every time we see a new undefined symbol, for
1530 // use in archive groups.
1532 // The index of the first global symbol in the output file.
1533 unsigned int first_global_index_
;
1534 // The file offset within the output symtab section where we should
1537 // The number of global symbols we want to write out.
1538 unsigned int output_count_
;
1539 // The file offset of the global dynamic symbols, or 0 if none.
1540 off_t dynamic_offset_
;
1541 // The index of the first global dynamic symbol.
1542 unsigned int first_dynamic_global_index_
;
1543 // The number of global dynamic symbols, or 0 if none.
1544 unsigned int dynamic_count_
;
1545 // The symbol hash table.
1546 Symbol_table_type table_
;
1547 // A pool of symbol names. This is used for all global symbols.
1548 // Entries in the hash table point into this pool.
1549 Stringpool namepool_
;
1550 // Forwarding symbols.
1551 Unordered_map
<const Symbol
*, Symbol
*> forwarders_
;
1552 // Weak aliases. A symbol in this list points to the next alias.
1553 // The aliases point to each other in a circular list.
1554 Unordered_map
<Symbol
*, Symbol
*> weak_aliases_
;
1555 // We don't expect there to be very many common symbols, so we keep
1556 // a list of them. When we find a common symbol we add it to this
1557 // list. It is possible that by the time we process the list the
1558 // symbol is no longer a common symbol. It may also have become a
1560 Commons_type commons_
;
1561 // This is like the commons_ field, except that it holds TLS common
1563 Commons_type tls_commons_
;
1564 // A list of symbols which have been forced to be local. We don't
1565 // expect there to be very many of them, so we keep a list of them
1566 // rather than walking the whole table to find them.
1567 Forced_locals forced_locals_
;
1568 // Manage symbol warnings.
1570 // Manage potential One Definition Rule (ODR) violations.
1571 Odr_map candidate_odr_violations_
;
1573 // When we emit a COPY reloc for a symbol, we define it in an
1574 // Output_data. When it's time to emit version information for it,
1575 // we need to know the dynamic object in which we found the original
1576 // definition. This maps symbols with COPY relocs to the dynamic
1577 // object where they were defined.
1578 Copied_symbol_dynobjs copied_symbol_dynobjs_
;
1579 // Information parsed from the version script, if any.
1580 const Version_script_info
& version_script_
;
1583 // We inline get_sized_symbol for efficiency.
1587 Symbol_table::get_sized_symbol(Symbol
* sym
) const
1589 gold_assert(size
== parameters
->target().get_size());
1590 return static_cast<Sized_symbol
<size
>*>(sym
);
1594 const Sized_symbol
<size
>*
1595 Symbol_table::get_sized_symbol(const Symbol
* sym
) const
1597 gold_assert(size
== parameters
->target().get_size());
1598 return static_cast<const Sized_symbol
<size
>*>(sym
);
1601 } // End namespace gold.
1603 #endif // !defined(GOLD_SYMTAB_H)