1 // symtab.h -- the gold symbol table -*- C++ -*-
3 // Copyright 2006, 2007 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"
43 template<int size
, bool big_endian
>
46 template<int size
, bool big_endian
>
49 class Version_script_info
;
57 // The base class of an entry in the symbol table. The symbol table
58 // can have a lot of entries, so we don't want this class to big.
59 // Size dependent fields can be found in the template class
60 // Sized_symbol. Targets may support their own derived classes.
65 // Because we want the class to be small, we don't use any virtual
66 // functions. But because symbols can be defined in different
67 // places, we need to classify them. This enum is the different
68 // sources of symbols we support.
71 // Symbol defined in a relocatable or dynamic input file--this is
72 // the most common case.
74 // Symbol defined in an Output_data, a special section created by
77 // Symbol defined in an Output_segment, with no associated
80 // Symbol value is constant.
84 // When the source is IN_OUTPUT_SEGMENT, we need to describe what
86 enum Segment_offset_base
88 // From the start of the segment.
90 // From the end of the segment.
92 // From the filesz of the segment--i.e., after the loaded bytes
93 // but before the bytes which are allocated but zeroed.
97 // Return the symbol name.
100 { return this->name_
; }
102 // Return the (ANSI) demangled version of the name, if
103 // parameters.demangle() is true. Otherwise, return the name. This
104 // is intended to be used only for logging errors, so it's not
107 demangled_name() const;
109 // Return the symbol version. This will return NULL for an
110 // unversioned symbol.
113 { return this->version_
; }
115 // Return whether this version is the default for this symbol name
116 // (eg, "foo@@V2" is a default version; "foo@V1" is not). Only
117 // meaningful for versioned symbols.
121 gold_assert(this->version_
!= NULL
);
122 return this->is_def_
;
125 // Set whether this version is the default for this symbol name.
127 set_is_default(bool def
)
128 { this->is_def_
= def
; }
130 // Return the symbol source.
133 { return this->source_
; }
135 // Return the object with which this symbol is associated.
139 gold_assert(this->source_
== FROM_OBJECT
);
140 return this->u_
.from_object
.object
;
143 // Return the index of the section in the input relocatable or
144 // dynamic object file.
148 gold_assert(this->source_
== FROM_OBJECT
);
149 return this->u_
.from_object
.shndx
;
152 // Return the output data section with which this symbol is
153 // associated, if the symbol was specially defined with respect to
154 // an output data section.
158 gold_assert(this->source_
== IN_OUTPUT_DATA
);
159 return this->u_
.in_output_data
.output_data
;
162 // If this symbol was defined with respect to an output data
163 // section, return whether the value is an offset from end.
165 offset_is_from_end() const
167 gold_assert(this->source_
== IN_OUTPUT_DATA
);
168 return this->u_
.in_output_data
.offset_is_from_end
;
171 // Return the output segment with which this symbol is associated,
172 // if the symbol was specially defined with respect to an output
175 output_segment() const
177 gold_assert(this->source_
== IN_OUTPUT_SEGMENT
);
178 return this->u_
.in_output_segment
.output_segment
;
181 // If this symbol was defined with respect to an output segment,
182 // return the offset base.
186 gold_assert(this->source_
== IN_OUTPUT_SEGMENT
);
187 return this->u_
.in_output_segment
.offset_base
;
190 // Return the symbol binding.
193 { return this->binding_
; }
195 // Return the symbol type.
198 { return this->type_
; }
200 // Return the symbol visibility.
203 { return this->visibility_
; }
205 // Return the non-visibility part of the st_other field.
208 { return this->nonvis_
; }
210 // Return whether this symbol is a forwarder. This will never be
211 // true of a symbol found in the hash table, but may be true of
212 // symbol pointers attached to object files.
215 { return this->is_forwarder_
; }
217 // Mark this symbol as a forwarder.
220 { this->is_forwarder_
= true; }
222 // Return whether this symbol has an alias in the weak aliases table
226 { return this->has_alias_
; }
228 // Mark this symbol as having an alias.
231 { this->has_alias_
= true; }
233 // Return whether this symbol needs an entry in the dynamic symbol
236 needs_dynsym_entry() const
238 return (this->needs_dynsym_entry_
239 || (this->in_reg() && this->in_dyn()));
242 // Mark this symbol as needing an entry in the dynamic symbol table.
244 set_needs_dynsym_entry()
245 { this->needs_dynsym_entry_
= true; }
247 // Return whether this symbol should be added to the dynamic symbol
250 should_add_dynsym_entry() const;
252 // Return whether this symbol has been seen in a regular object.
255 { return this->in_reg_
; }
257 // Mark this symbol as having been seen in a regular object.
260 { this->in_reg_
= true; }
262 // Return whether this symbol has been seen in a dynamic object.
265 { return this->in_dyn_
; }
267 // Mark this symbol as having been seen in a dynamic object.
270 { this->in_dyn_
= true; }
272 // Return the index of this symbol in the output file symbol table.
273 // A value of -1U means that this symbol is not going into the
274 // output file. This starts out as zero, and is set to a non-zero
275 // value by Symbol_table::finalize. It is an error to ask for the
276 // symbol table index before it has been set.
280 gold_assert(this->symtab_index_
!= 0);
281 return this->symtab_index_
;
284 // Set the index of the symbol in the output file symbol table.
286 set_symtab_index(unsigned int index
)
288 gold_assert(index
!= 0);
289 this->symtab_index_
= index
;
292 // Return whether this symbol already has an index in the output
293 // file symbol table.
295 has_symtab_index() const
296 { return this->symtab_index_
!= 0; }
298 // Return the index of this symbol in the dynamic symbol table. A
299 // value of -1U means that this symbol is not going into the dynamic
300 // symbol table. This starts out as zero, and is set to a non-zero
301 // during Layout::finalize. It is an error to ask for the dynamic
302 // symbol table index before it has been set.
306 gold_assert(this->dynsym_index_
!= 0);
307 return this->dynsym_index_
;
310 // Set the index of the symbol in the dynamic symbol table.
312 set_dynsym_index(unsigned int index
)
314 gold_assert(index
!= 0);
315 this->dynsym_index_
= index
;
318 // Return whether this symbol already has an index in the dynamic
321 has_dynsym_index() const
322 { return this->dynsym_index_
!= 0; }
324 // Return whether this symbol has an entry in the GOT section.
325 // For a TLS symbol, this GOT entry will hold its tp-relative offset.
327 has_got_offset() const
328 { return this->has_got_offset_
; }
330 // Return the offset into the GOT section of this symbol.
334 gold_assert(this->has_got_offset());
335 return this->got_offset_
;
338 // Set the GOT offset of this symbol.
340 set_got_offset(unsigned int got_offset
)
342 this->has_got_offset_
= true;
343 this->got_offset_
= got_offset
;
346 // Return whether this TLS symbol has an entry in the GOT section for
347 // its module index or, if NEED_PAIR is true, has a pair of entries
348 // for its module index and dtv-relative offset.
350 has_tls_got_offset(bool need_pair
) const
352 return (this->has_tls_mod_got_offset_
353 && (!need_pair
|| this->has_tls_pair_got_offset_
));
356 // Return the offset into the GOT section for this symbol's TLS module
357 // index or, if NEED_PAIR is true, for the pair of entries for the
358 // module index and dtv-relative offset.
360 tls_got_offset(bool need_pair
) const
362 gold_assert(this->has_tls_got_offset(need_pair
));
363 return this->tls_mod_got_offset_
;
366 // Set the GOT offset of this symbol.
368 set_tls_got_offset(unsigned int got_offset
, bool have_pair
)
370 this->has_tls_mod_got_offset_
= true;
371 this->has_tls_pair_got_offset_
= have_pair
;
372 this->tls_mod_got_offset_
= got_offset
;
375 // Return whether this symbol has an entry in the PLT section.
377 has_plt_offset() const
378 { return this->has_plt_offset_
; }
380 // Return the offset into the PLT section of this symbol.
384 gold_assert(this->has_plt_offset());
385 return this->plt_offset_
;
388 // Set the PLT offset of this symbol.
390 set_plt_offset(unsigned int plt_offset
)
392 this->has_plt_offset_
= true;
393 this->plt_offset_
= plt_offset
;
396 // Return whether this dynamic symbol needs a special value in the
397 // dynamic symbol table.
399 needs_dynsym_value() const
400 { return this->needs_dynsym_value_
; }
402 // Set that this dynamic symbol needs a special value in the dynamic
405 set_needs_dynsym_value()
407 gold_assert(this->object()->is_dynamic());
408 this->needs_dynsym_value_
= true;
411 // Return true if the final value of this symbol is known at link
414 final_value_is_known() const;
416 // Return whether this is a defined symbol (not undefined or
421 return (this->source_
!= FROM_OBJECT
422 || (this->shndx() != elfcpp::SHN_UNDEF
423 && this->shndx() != elfcpp::SHN_COMMON
));
426 // Return true if this symbol is from a dynamic object.
428 is_from_dynobj() const
430 return this->source_
== FROM_OBJECT
&& this->object()->is_dynamic();
433 // Return whether this is an undefined symbol.
437 return this->source_
== FROM_OBJECT
&& this->shndx() == elfcpp::SHN_UNDEF
;
440 // Return whether this is a common symbol.
444 return (this->source_
== FROM_OBJECT
445 && (this->shndx() == elfcpp::SHN_COMMON
446 || this->type_
== elfcpp::STT_COMMON
));
449 // Return whether this symbol can be seen outside this object.
451 is_externally_visible() const
453 return (this->visibility_
== elfcpp::STV_DEFAULT
454 || this->visibility_
== elfcpp::STV_PROTECTED
);
457 // Return true if this symbol can be preempted by a definition in
458 // another link unit.
460 is_preemptible() const
462 // It doesn't make sense to ask whether a symbol defined in
463 // another object is preemptible.
464 gold_assert(!this->is_from_dynobj());
466 return (this->visibility_
!= elfcpp::STV_INTERNAL
467 && this->visibility_
!= elfcpp::STV_HIDDEN
468 && this->visibility_
!= elfcpp::STV_PROTECTED
469 && !this->is_forced_local_
470 && parameters
->output_is_shared()
471 && !parameters
->symbolic());
474 // Return true if this symbol is a function that needs a PLT entry.
475 // If the symbol is defined in a dynamic object or if it is subject
476 // to pre-emption, we need to make a PLT entry.
478 needs_plt_entry() const
480 return (this->type() == elfcpp::STT_FUNC
481 && (this->is_from_dynobj() || this->is_preemptible()));
484 // When determining whether a reference to a symbol needs a dynamic
485 // relocation, we need to know several things about the reference.
486 // These flags may be or'ed together.
489 // Reference to the symbol's absolute address.
491 // A non-PIC reference.
497 // Given a direct absolute or pc-relative static relocation against
498 // the global symbol, this function returns whether a dynamic relocation
502 needs_dynamic_reloc(int flags
) const
504 // An absolute reference within a position-independent output file
505 // will need a dynamic relocation.
506 if ((flags
& ABSOLUTE_REF
)
507 && parameters
->output_is_position_independent())
510 // A function call that can branch to a local PLT entry does not need
511 // a dynamic relocation.
512 if ((flags
& FUNCTION_CALL
) && this->has_plt_offset())
515 // A non-pic pc-relative function call in a shared library whose target
516 // is defined in the same load module does not need a dynamic relocation.
517 // Even if the target is preemptible, we will bind directly, since we
518 // cannot use a PLT entry in this case.
519 if ((flags
& FUNCTION_CALL
)
520 && (flags
& NON_PIC_REF
)
521 && this->is_defined()
522 && parameters
->output_is_shared())
525 // A reference to any PLT entry in a non-position-independent executable
526 // does not need a dynamic relocation.
527 if (!parameters
->output_is_position_independent()
528 && this->has_plt_offset())
531 // A reference to a symbol defined in a dynamic object or to a
532 // symbol that is preemptible will need a dynamic relocation.
533 if (this->is_from_dynobj() || this->is_preemptible())
536 // For all other cases, return FALSE.
540 // Given a direct absolute static relocation against
541 // the global symbol, where a dynamic relocation is needed, this
542 // function returns whether a relative dynamic relocation can be used.
543 // The caller must determine separately whether the static relocation
544 // is compatible with a relative relocation.
547 can_use_relative_reloc(bool is_function_call
) const
549 // A function call that can branch to a local PLT entry can
550 // use a RELATIVE relocation.
551 if (is_function_call
&& this->has_plt_offset())
554 // A reference to a symbol defined in a dynamic object or to a
555 // symbol that is preemptible can not use a RELATIVE relocaiton.
556 if (this->is_from_dynobj() || this->is_preemptible())
559 // For all other cases, return TRUE.
563 // Return whether there should be a warning for references to this
567 { return this->has_warning_
; }
569 // Mark this symbol as having a warning.
572 { this->has_warning_
= true; }
574 // Return whether this symbol is defined by a COPY reloc from a
577 is_copied_from_dynobj() const
578 { return this->is_copied_from_dynobj_
; }
580 // Mark this symbol as defined by a COPY reloc.
582 set_is_copied_from_dynobj()
583 { this->is_copied_from_dynobj_
= true; }
585 // Return whether this symbol is forced to visibility STB_LOCAL
586 // by a "local:" entry in a version script.
588 is_forced_local() const
589 { return this->is_forced_local_
; }
591 // Mark this symbol as forced to STB_LOCAL visibility.
593 set_is_forced_local()
594 { this->is_forced_local_
= true; }
597 // Instances of this class should always be created at a specific
600 { memset(this, 0, sizeof *this); }
602 // Initialize the general fields.
604 init_fields(const char* name
, const char* version
,
605 elfcpp::STT type
, elfcpp::STB binding
,
606 elfcpp::STV visibility
, unsigned char nonvis
);
608 // Initialize fields from an ELF symbol in OBJECT.
609 template<int size
, bool big_endian
>
611 init_base(const char *name
, const char* version
, Object
* object
,
612 const elfcpp::Sym
<size
, big_endian
>&);
614 // Initialize fields for an Output_data.
616 init_base(const char* name
, Output_data
*, elfcpp::STT
, elfcpp::STB
,
617 elfcpp::STV
, unsigned char nonvis
, bool offset_is_from_end
);
619 // Initialize fields for an Output_segment.
621 init_base(const char* name
, Output_segment
* os
, elfcpp::STT type
,
622 elfcpp::STB binding
, elfcpp::STV visibility
,
623 unsigned char nonvis
, Segment_offset_base offset_base
);
625 // Initialize fields for a constant.
627 init_base(const char* name
, elfcpp::STT type
, elfcpp::STB binding
,
628 elfcpp::STV visibility
, unsigned char nonvis
);
630 // Override existing symbol.
631 template<int size
, bool big_endian
>
633 override_base(const elfcpp::Sym
<size
, big_endian
>&, Object
* object
,
634 const char* version
);
636 // Override existing symbol with a special symbol.
638 override_base_with_special(const Symbol
* from
);
640 // Allocate a common symbol by giving it a location in the output
643 allocate_base_common(Output_data
*);
646 Symbol(const Symbol
&);
647 Symbol
& operator=(const Symbol
&);
649 // Symbol name (expected to point into a Stringpool).
651 // Symbol version (expected to point into a Stringpool). This may
653 const char* version_
;
657 // This struct is used if SOURCE_ == FROM_OBJECT.
660 // Object in which symbol is defined, or in which it was first
663 // Section number in object_ in which symbol is defined.
667 // This struct is used if SOURCE_ == IN_OUTPUT_DATA.
670 // Output_data in which symbol is defined. Before
671 // Layout::finalize the symbol's value is an offset within the
673 Output_data
* output_data
;
674 // True if the offset is from the end, false if the offset is
675 // from the beginning.
676 bool offset_is_from_end
;
679 // This struct is used if SOURCE_ == IN_OUTPUT_SEGMENT.
682 // Output_segment in which the symbol is defined. Before
683 // Layout::finalize the symbol's value is an offset.
684 Output_segment
* output_segment
;
685 // The base to use for the offset before Layout::finalize.
686 Segment_offset_base offset_base
;
690 // The index of this symbol in the output file. If the symbol is
691 // not going into the output file, this value is -1U. This field
692 // starts as always holding zero. It is set to a non-zero value by
693 // Symbol_table::finalize.
694 unsigned int symtab_index_
;
696 // The index of this symbol in the dynamic symbol table. If the
697 // symbol is not going into the dynamic symbol table, this value is
698 // -1U. This field starts as always holding zero. It is set to a
699 // non-zero value during Layout::finalize.
700 unsigned int dynsym_index_
;
702 // If this symbol has an entry in the GOT section (has_got_offset_
703 // is true), this is the offset from the start of the GOT section.
704 // For a TLS symbol, if has_tls_tpoff_got_offset_ is true, this
705 // serves as the GOT offset for the GOT entry that holds its
706 // TP-relative offset.
707 unsigned int got_offset_
;
709 // If this is a TLS symbol and has an entry in the GOT section
710 // for a module index or a pair of entries (module index,
711 // dtv-relative offset), these are the offsets from the start
712 // of the GOT section.
713 unsigned int tls_mod_got_offset_
;
714 unsigned int tls_pair_got_offset_
;
716 // If this symbol has an entry in the PLT section (has_plt_offset_
717 // is true), then this is the offset from the start of the PLT
719 unsigned int plt_offset_
;
722 elfcpp::STT type_
: 4;
724 elfcpp::STB binding_
: 4;
725 // Symbol visibility.
726 elfcpp::STV visibility_
: 2;
727 // Rest of symbol st_other field.
728 unsigned int nonvis_
: 6;
729 // The type of symbol.
731 // True if this symbol always requires special target-specific
733 bool is_target_special_
: 1;
734 // True if this is the default version of the symbol.
736 // True if this symbol really forwards to another symbol. This is
737 // used when we discover after the fact that two different entries
738 // in the hash table really refer to the same symbol. This will
739 // never be set for a symbol found in the hash table, but may be set
740 // for a symbol found in the list of symbols attached to an Object.
741 // It forwards to the symbol found in the forwarders_ map of
743 bool is_forwarder_
: 1;
744 // True if the symbol has an alias in the weak_aliases table in
747 // True if this symbol needs to be in the dynamic symbol table.
748 bool needs_dynsym_entry_
: 1;
749 // True if we've seen this symbol in a regular object.
751 // True if we've seen this symbol in a dynamic object.
753 // True if the symbol has an entry in the GOT section.
754 // For a TLS symbol, this GOT entry will hold its tp-relative offset.
755 bool has_got_offset_
: 1;
756 // True if the symbol has an entry in the GOT section for its
758 bool has_tls_mod_got_offset_
: 1;
759 // True if the symbol has a pair of entries in the GOT section for its
760 // module index and dtv-relative offset.
761 bool has_tls_pair_got_offset_
: 1;
762 // True if the symbol has an entry in the PLT section.
763 bool has_plt_offset_
: 1;
764 // True if this is a dynamic symbol which needs a special value in
765 // the dynamic symbol table.
766 bool needs_dynsym_value_
: 1;
767 // True if there is a warning for this symbol.
768 bool has_warning_
: 1;
769 // True if we are using a COPY reloc for this symbol, so that the
770 // real definition lives in a dynamic object.
771 bool is_copied_from_dynobj_
: 1;
772 // True if this symbol was forced to local visibility by a version
774 bool is_forced_local_
: 1;
777 // The parts of a symbol which are size specific. Using a template
778 // derived class like this helps us use less space on a 32-bit system.
781 class Sized_symbol
: public Symbol
784 typedef typename
elfcpp::Elf_types
<size
>::Elf_Addr Value_type
;
785 typedef typename
elfcpp::Elf_types
<size
>::Elf_WXword Size_type
;
790 // Initialize fields from an ELF symbol in OBJECT.
791 template<bool big_endian
>
793 init(const char *name
, const char* version
, Object
* object
,
794 const elfcpp::Sym
<size
, big_endian
>&);
796 // Initialize fields for an Output_data.
798 init(const char* name
, Output_data
*, Value_type value
, Size_type symsize
,
799 elfcpp::STT
, elfcpp::STB
, elfcpp::STV
, unsigned char nonvis
,
800 bool offset_is_from_end
);
802 // Initialize fields for an Output_segment.
804 init(const char* name
, Output_segment
*, Value_type value
, Size_type symsize
,
805 elfcpp::STT
, elfcpp::STB
, elfcpp::STV
, unsigned char nonvis
,
806 Segment_offset_base offset_base
);
808 // Initialize fields for a constant.
810 init(const char* name
, Value_type value
, Size_type symsize
,
811 elfcpp::STT
, elfcpp::STB
, elfcpp::STV
, unsigned char nonvis
);
813 // Override existing symbol.
814 template<bool big_endian
>
816 override(const elfcpp::Sym
<size
, big_endian
>&, Object
* object
,
817 const char* version
);
819 // Override existing symbol with a special symbol.
821 override_with_special(const Sized_symbol
<size
>*);
823 // Return the symbol's value.
826 { return this->value_
; }
828 // Return the symbol's size (we can't call this 'size' because that
829 // is a template parameter).
832 { return this->symsize_
; }
834 // Set the symbol size. This is used when resolving common symbols.
836 set_symsize(Size_type symsize
)
837 { this->symsize_
= symsize
; }
839 // Set the symbol value. This is called when we store the final
840 // values of the symbols into the symbol table.
842 set_value(Value_type value
)
843 { this->value_
= value
; }
845 // Allocate a common symbol by giving it a location in the output
848 allocate_common(Output_data
*, Value_type value
);
851 Sized_symbol(const Sized_symbol
&);
852 Sized_symbol
& operator=(const Sized_symbol
&);
854 // Symbol value. Before Layout::finalize this is the offset in the
855 // input section. This is set to the final value during
862 // A struct describing a symbol defined by the linker, where the value
863 // of the symbol is defined based on an output section. This is used
864 // for symbols defined by the linker, like "_init_array_start".
866 struct Define_symbol_in_section
870 // The name of the output section with which this symbol should be
871 // associated. If there is no output section with that name, the
872 // symbol will be defined as zero.
873 const char* output_section
;
874 // The offset of the symbol within the output section. This is an
875 // offset from the start of the output section, unless start_at_end
876 // is true, in which case this is an offset from the end of the
879 // The size of the symbol.
883 // The symbol binding.
885 // The symbol visibility.
886 elfcpp::STV visibility
;
887 // The rest of the st_other field.
888 unsigned char nonvis
;
889 // If true, the value field is an offset from the end of the output
891 bool offset_is_from_end
;
892 // If true, this symbol is defined only if we see a reference to it.
896 // A struct describing a symbol defined by the linker, where the value
897 // of the symbol is defined based on a segment. This is used for
898 // symbols defined by the linker, like "_end". We describe the
899 // segment with which the symbol should be associated by its
900 // characteristics. If no segment meets these characteristics, the
901 // symbol will be defined as zero. If there is more than one segment
902 // which meets these characteristics, we will use the first one.
904 struct Define_symbol_in_segment
908 // The segment type where the symbol should be defined, typically
910 elfcpp::PT segment_type
;
911 // Bitmask of segment flags which must be set.
912 elfcpp::PF segment_flags_set
;
913 // Bitmask of segment flags which must be clear.
914 elfcpp::PF segment_flags_clear
;
915 // The offset of the symbol within the segment. The offset is
916 // calculated from the position set by offset_base.
918 // The size of the symbol.
922 // The symbol binding.
924 // The symbol visibility.
925 elfcpp::STV visibility
;
926 // The rest of the st_other field.
927 unsigned char nonvis
;
928 // The base from which we compute the offset.
929 Symbol::Segment_offset_base offset_base
;
930 // If true, this symbol is defined only if we see a reference to it.
934 // This class manages warnings. Warnings are a GNU extension. When
935 // we see a section named .gnu.warning.SYM in an object file, and if
936 // we wind using the definition of SYM from that object file, then we
937 // will issue a warning for any relocation against SYM from a
938 // different object file. The text of the warning is the contents of
939 // the section. This is not precisely the definition used by the old
940 // GNU linker; the old GNU linker treated an occurrence of
941 // .gnu.warning.SYM as defining a warning symbol. A warning symbol
942 // would trigger a warning on any reference. However, it was
943 // inconsistent in that a warning in a dynamic object only triggered
944 // if there was no definition in a regular object. This linker is
945 // different in that we only issue a warning if we use the symbol
946 // definition from the same object file as the warning section.
955 // Add a warning for symbol NAME in object OBJ. WARNING is the text
958 add_warning(Symbol_table
* symtab
, const char* name
, Object
* obj
,
959 const std::string
& warning
);
961 // For each symbol for which we should give a warning, make a note
964 note_warnings(Symbol_table
* symtab
);
966 // Issue a warning for a reference to SYM at RELINFO's location.
967 template<int size
, bool big_endian
>
969 issue_warning(const Symbol
* sym
, const Relocate_info
<size
, big_endian
>*,
970 size_t relnum
, off_t reloffset
) const;
973 Warnings(const Warnings
&);
974 Warnings
& operator=(const Warnings
&);
976 // What we need to know to get the warning text.
977 struct Warning_location
979 // The object the warning is in.
985 : object(NULL
), text()
989 set(Object
* o
, const std::string
& t
)
996 // A mapping from warning symbol names (canonicalized in
997 // Symbol_table's namepool_ field) to warning information.
998 typedef Unordered_map
<const char*, Warning_location
> Warning_table
;
1000 Warning_table warnings_
;
1003 // The main linker symbol table.
1008 // COUNT is an estimate of how many symbosl will be inserted in the
1009 // symbol table. It's ok to put 0 if you don't know; a correct
1010 // guess will just save some CPU by reducing hashtable resizes.
1011 Symbol_table(unsigned int count
, const Version_script_info
& version_script
);
1015 // Add COUNT external symbols from the relocatable object RELOBJ to
1016 // the symbol table. SYMS is the symbols, SYM_NAMES is their names,
1017 // SYM_NAME_SIZE is the size of SYM_NAMES. This sets SYMPOINTERS to
1018 // point to the symbols in the symbol table.
1019 template<int size
, bool big_endian
>
1021 add_from_relobj(Sized_relobj
<size
, big_endian
>* relobj
,
1022 const unsigned char* syms
, size_t count
,
1023 const char* sym_names
, size_t sym_name_size
,
1024 typename Sized_relobj
<size
, big_endian
>::Symbols
*);
1026 // Add COUNT dynamic symbols from the dynamic object DYNOBJ to the
1027 // symbol table. SYMS is the symbols. SYM_NAMES is their names.
1028 // SYM_NAME_SIZE is the size of SYM_NAMES. The other parameters are
1029 // symbol version data.
1030 template<int size
, bool big_endian
>
1032 add_from_dynobj(Sized_dynobj
<size
, big_endian
>* dynobj
,
1033 const unsigned char* syms
, size_t count
,
1034 const char* sym_names
, size_t sym_name_size
,
1035 const unsigned char* versym
, size_t versym_size
,
1036 const std::vector
<const char*>*);
1038 // Define a special symbol based on an Output_data. It is a
1039 // multiple definition error if this symbol is already defined.
1041 define_in_output_data(const Target
*, const char* name
, const char* version
,
1042 Output_data
*, uint64_t value
, uint64_t symsize
,
1043 elfcpp::STT type
, elfcpp::STB binding
,
1044 elfcpp::STV visibility
, unsigned char nonvis
,
1045 bool offset_is_from_end
, bool only_if_ref
);
1047 // Define a special symbol based on an Output_segment. It is a
1048 // multiple definition error if this symbol is already defined.
1050 define_in_output_segment(const Target
*, const char* name
,
1051 const char* version
, Output_segment
*,
1052 uint64_t value
, uint64_t symsize
,
1053 elfcpp::STT type
, elfcpp::STB binding
,
1054 elfcpp::STV visibility
, unsigned char nonvis
,
1055 Symbol::Segment_offset_base
, bool only_if_ref
);
1057 // Define a special symbol with a constant value. It is a multiple
1058 // definition error if this symbol is already defined.
1060 define_as_constant(const Target
*, const char* name
, const char* version
,
1061 uint64_t value
, uint64_t symsize
, elfcpp::STT type
,
1062 elfcpp::STB binding
, elfcpp::STV visibility
,
1063 unsigned char nonvis
, bool only_if_ref
);
1065 // Define a set of symbols in output sections.
1067 define_symbols(const Layout
*, const Target
*, int count
,
1068 const Define_symbol_in_section
*);
1070 // Define a set of symbols in output segments.
1072 define_symbols(const Layout
*, const Target
*, int count
,
1073 const Define_symbol_in_segment
*);
1075 // Define SYM using a COPY reloc. POSD is the Output_data where the
1076 // symbol should be defined--typically a .dyn.bss section. VALUE is
1077 // the offset within POSD.
1080 define_with_copy_reloc(const Target
*, Sized_symbol
<size
>* sym
,
1082 typename
elfcpp::Elf_types
<size
>::Elf_Addr
);
1084 // Look up a symbol.
1086 lookup(const char*, const char* version
= NULL
) const;
1088 // Return the real symbol associated with the forwarder symbol FROM.
1090 resolve_forwards(const Symbol
* from
) const;
1092 // Return the sized version of a symbol in this table.
1095 get_sized_symbol(Symbol
* ACCEPT_SIZE
) const;
1098 const Sized_symbol
<size
>*
1099 get_sized_symbol(const Symbol
* ACCEPT_SIZE
) const;
1101 // Return the count of undefined symbols seen.
1103 saw_undefined() const
1104 { return this->saw_undefined_
; }
1106 // Allocate the common symbols
1108 allocate_commons(const General_options
&, Layout
*);
1110 // Add a warning for symbol NAME in object OBJ. WARNING is the text
1113 add_warning(const char* name
, Object
* obj
, const std::string
& warning
)
1114 { this->warnings_
.add_warning(this, name
, obj
, warning
); }
1116 // Canonicalize a symbol name for use in the hash table.
1118 canonicalize_name(const char* name
)
1119 { return this->namepool_
.add(name
, true, NULL
); }
1121 // Possibly issue a warning for a reference to SYM at LOCATION which
1123 template<int size
, bool big_endian
>
1125 issue_warning(const Symbol
* sym
,
1126 const Relocate_info
<size
, big_endian
>* relinfo
,
1127 size_t relnum
, off_t reloffset
) const
1128 { this->warnings_
.issue_warning(sym
, relinfo
, relnum
, reloffset
); }
1130 // Check candidate_odr_violations_ to find symbols with the same name
1131 // but apparently different definitions (different source-file/line-no).
1133 detect_odr_violations(const Task
*, const char* output_file_name
) const;
1135 // SYM is defined using a COPY reloc. Return the dynamic object
1136 // where the original definition was found.
1138 get_copy_source(const Symbol
* sym
) const;
1140 // Set the dynamic symbol indexes. INDEX is the index of the first
1141 // global dynamic symbol. Pointers to the symbols are stored into
1142 // the vector. The names are stored into the Stringpool. This
1143 // returns an updated dynamic symbol index.
1145 set_dynsym_indexes(const Target
*, unsigned int index
,
1146 std::vector
<Symbol
*>*, Stringpool
*, Versions
*);
1148 // Finalize the symbol table after we have set the final addresses
1149 // of all the input sections. This sets the final symbol indexes,
1150 // values and adds the names to *POOL. *PLOCAL_SYMCOUNT is the
1151 // index of the first global symbol. OFF is the file offset of the
1152 // global symbol table, DYNOFF is the offset of the globals in the
1153 // dynamic symbol table, DYN_GLOBAL_INDEX is the index of the first
1154 // global dynamic symbol, and DYNCOUNT is the number of global
1155 // dynamic symbols. This records the parameters, and returns the
1156 // new file offset. It updates *PLOCAL_SYMCOUNT if it created any
1159 finalize(off_t off
, off_t dynoff
, size_t dyn_global_index
, size_t dyncount
,
1160 Stringpool
* pool
, unsigned int *plocal_symcount
);
1162 // Write out the global symbols.
1164 write_globals(const Input_objects
*, const Stringpool
*, const Stringpool
*,
1165 Output_file
*) const;
1167 // Write out a section symbol. Return the updated offset.
1169 write_section_symbol(const Output_section
*, Output_file
*, off_t
) const;
1171 // Dump statistical information to stderr.
1173 print_stats() const;
1175 // Return the version script information.
1176 const Version_script_info
&
1177 version_script() const
1178 { return version_script_
; }
1181 Symbol_table(const Symbol_table
&);
1182 Symbol_table
& operator=(const Symbol_table
&);
1184 // Make FROM a forwarder symbol to TO.
1186 make_forwarder(Symbol
* from
, Symbol
* to
);
1189 template<int size
, bool big_endian
>
1191 add_from_object(Object
*, const char *name
, Stringpool::Key name_key
,
1192 const char *version
, Stringpool::Key version_key
,
1193 bool def
, const elfcpp::Sym
<size
, big_endian
>& sym
,
1194 const elfcpp::Sym
<size
, big_endian
>& orig_sym
);
1197 template<int size
, bool big_endian
>
1199 resolve(Sized_symbol
<size
>* to
,
1200 const elfcpp::Sym
<size
, big_endian
>& sym
,
1201 const elfcpp::Sym
<size
, big_endian
>& orig_sym
,
1202 Object
*, const char* version
);
1204 template<int size
, bool big_endian
>
1206 resolve(Sized_symbol
<size
>* to
, const Sized_symbol
<size
>* from
,
1207 const char* version ACCEPT_SIZE_ENDIAN
);
1209 // Record that a symbol is forced to be local by a version script.
1211 force_local(Symbol
*);
1213 // Whether we should override a symbol, based on flags in
1216 should_override(const Symbol
*, unsigned int, Object
*, bool*);
1218 // Override a symbol.
1219 template<int size
, bool big_endian
>
1221 override(Sized_symbol
<size
>* tosym
,
1222 const elfcpp::Sym
<size
, big_endian
>& fromsym
,
1223 Object
* object
, const char* version
);
1225 // Whether we should override a symbol with a special symbol which
1226 // is automatically defined by the linker.
1228 should_override_with_special(const Symbol
*);
1230 // Override a symbol with a special symbol.
1233 override_with_special(Sized_symbol
<size
>* tosym
,
1234 const Sized_symbol
<size
>* fromsym
);
1236 // Record all weak alias sets for a dynamic object.
1239 record_weak_aliases(std::vector
<Sized_symbol
<size
>*>*);
1241 // Define a special symbol.
1242 template<int size
, bool big_endian
>
1244 define_special_symbol(const Target
* target
, const char** pname
,
1245 const char** pversion
, bool only_if_ref
,
1246 Sized_symbol
<size
>** poldsym ACCEPT_SIZE_ENDIAN
);
1248 // Define a symbol in an Output_data, sized version.
1251 do_define_in_output_data(const Target
*, const char* name
,
1252 const char* version
, Output_data
*,
1253 typename
elfcpp::Elf_types
<size
>::Elf_Addr value
,
1254 typename
elfcpp::Elf_types
<size
>::Elf_WXword ssize
,
1255 elfcpp::STT type
, elfcpp::STB binding
,
1256 elfcpp::STV visibility
, unsigned char nonvis
,
1257 bool offset_is_from_end
, bool only_if_ref
);
1259 // Define a symbol in an Output_segment, sized version.
1262 do_define_in_output_segment(
1263 const Target
*, const char* name
, const char* version
, Output_segment
* os
,
1264 typename
elfcpp::Elf_types
<size
>::Elf_Addr value
,
1265 typename
elfcpp::Elf_types
<size
>::Elf_WXword ssize
,
1266 elfcpp::STT type
, elfcpp::STB binding
,
1267 elfcpp::STV visibility
, unsigned char nonvis
,
1268 Symbol::Segment_offset_base offset_base
, bool only_if_ref
);
1270 // Define a symbol as a constant, sized version.
1273 do_define_as_constant(
1274 const Target
*, const char* name
, const char* version
,
1275 typename
elfcpp::Elf_types
<size
>::Elf_Addr value
,
1276 typename
elfcpp::Elf_types
<size
>::Elf_WXword ssize
,
1277 elfcpp::STT type
, elfcpp::STB binding
,
1278 elfcpp::STV visibility
, unsigned char nonvis
,
1281 // Allocate the common symbols, sized version.
1284 do_allocate_commons(const General_options
&, Layout
*);
1286 // Implement detect_odr_violations.
1287 template<int size
, bool big_endian
>
1289 sized_detect_odr_violations() const;
1291 // Finalize symbols specialized for size.
1294 sized_finalize(off_t
, Stringpool
*, unsigned int*);
1296 // Finalize a symbol. Return whether it should be added to the
1300 sized_finalize_symbol(Symbol
*);
1302 // Add a symbol the final symtab by setting its index.
1305 add_to_final_symtab(Symbol
*, Stringpool
*, unsigned int* pindex
, off_t
* poff
);
1307 // Write globals specialized for size and endianness.
1308 template<int size
, bool big_endian
>
1310 sized_write_globals(const Input_objects
*, const Stringpool
*,
1311 const Stringpool
*, Output_file
*) const;
1313 // Write out a symbol to P.
1314 template<int size
, bool big_endian
>
1316 sized_write_symbol(Sized_symbol
<size
>*,
1317 typename
elfcpp::Elf_types
<size
>::Elf_Addr value
,
1319 const Stringpool
*, unsigned char* p
1320 ACCEPT_SIZE_ENDIAN
) const;
1322 // Possibly warn about an undefined symbol from a dynamic object.
1324 warn_about_undefined_dynobj_symbol(const Input_objects
*, Symbol
*) const;
1326 // Write out a section symbol, specialized for size and endianness.
1327 template<int size
, bool big_endian
>
1329 sized_write_section_symbol(const Output_section
*, Output_file
*, off_t
) const;
1331 // The type of the symbol hash table.
1333 typedef std::pair
<Stringpool::Key
, Stringpool::Key
> Symbol_table_key
;
1335 struct Symbol_table_hash
1338 operator()(const Symbol_table_key
&) const;
1341 struct Symbol_table_eq
1344 operator()(const Symbol_table_key
&, const Symbol_table_key
&) const;
1347 typedef Unordered_map
<Symbol_table_key
, Symbol
*, Symbol_table_hash
,
1348 Symbol_table_eq
> Symbol_table_type
;
1350 // The type of the list of common symbols.
1351 typedef std::vector
<Symbol
*> Commons_type
;
1353 // The type of the list of symbols which have been forced local.
1354 typedef std::vector
<Symbol
*> Forced_locals
;
1356 // A map from symbols with COPY relocs to the dynamic objects where
1357 // they are defined.
1358 typedef Unordered_map
<const Symbol
*, Dynobj
*> Copied_symbol_dynobjs
;
1360 // A map from symbol name (as a pointer into the namepool) to all
1361 // the locations the symbols is (weakly) defined (and certain other
1362 // conditions are met). This map will be used later to detect
1363 // possible One Definition Rule (ODR) violations.
1364 struct Symbol_location
1366 Object
* object
; // Object where the symbol is defined.
1367 unsigned int shndx
; // Section-in-object where the symbol is defined.
1368 off_t offset
; // Offset-in-section where the symbol is defined.
1369 bool operator==(const Symbol_location
& that
) const
1371 return (this->object
== that
.object
1372 && this->shndx
== that
.shndx
1373 && this->offset
== that
.offset
);
1377 struct Symbol_location_hash
1379 size_t operator()(const Symbol_location
& loc
) const
1380 { return reinterpret_cast<uintptr_t>(loc
.object
) ^ loc
.offset
^ loc
.shndx
; }
1383 typedef Unordered_map
<const char*,
1384 Unordered_set
<Symbol_location
, Symbol_location_hash
> >
1387 // We increment this every time we see a new undefined symbol, for
1388 // use in archive groups.
1390 // The index of the first global symbol in the output file.
1391 unsigned int first_global_index_
;
1392 // The file offset within the output symtab section where we should
1395 // The number of global symbols we want to write out.
1396 unsigned int output_count_
;
1397 // The file offset of the global dynamic symbols, or 0 if none.
1398 off_t dynamic_offset_
;
1399 // The index of the first global dynamic symbol.
1400 unsigned int first_dynamic_global_index_
;
1401 // The number of global dynamic symbols, or 0 if none.
1402 unsigned int dynamic_count_
;
1403 // The symbol hash table.
1404 Symbol_table_type table_
;
1405 // A pool of symbol names. This is used for all global symbols.
1406 // Entries in the hash table point into this pool.
1407 Stringpool namepool_
;
1408 // Forwarding symbols.
1409 Unordered_map
<const Symbol
*, Symbol
*> forwarders_
;
1410 // Weak aliases. A symbol in this list points to the next alias.
1411 // The aliases point to each other in a circular list.
1412 Unordered_map
<Symbol
*, Symbol
*> weak_aliases_
;
1413 // We don't expect there to be very many common symbols, so we keep
1414 // a list of them. When we find a common symbol we add it to this
1415 // list. It is possible that by the time we process the list the
1416 // symbol is no longer a common symbol. It may also have become a
1418 Commons_type commons_
;
1419 // A list of symbols which have been forced to be local. We don't
1420 // expect there to be very many of them, so we keep a list of them
1421 // rather than walking the whole table to find them.
1422 Forced_locals forced_locals_
;
1423 // Manage symbol warnings.
1425 // Manage potential One Definition Rule (ODR) violations.
1426 Odr_map candidate_odr_violations_
;
1428 // When we emit a COPY reloc for a symbol, we define it in an
1429 // Output_data. When it's time to emit version information for it,
1430 // we need to know the dynamic object in which we found the original
1431 // definition. This maps symbols with COPY relocs to the dynamic
1432 // object where they were defined.
1433 Copied_symbol_dynobjs copied_symbol_dynobjs_
;
1434 // Information parsed from the version script, if any.
1435 const Version_script_info
& version_script_
;
1438 // We inline get_sized_symbol for efficiency.
1442 Symbol_table::get_sized_symbol(Symbol
* sym ACCEPT_SIZE
) const
1444 gold_assert(size
== parameters
->get_size());
1445 return static_cast<Sized_symbol
<size
>*>(sym
);
1449 const Sized_symbol
<size
>*
1450 Symbol_table::get_sized_symbol(const Symbol
* sym ACCEPT_SIZE
) const
1452 gold_assert(size
== parameters
->get_size());
1453 return static_cast<const Sized_symbol
<size
>*>(sym
);
1456 } // End namespace gold.
1458 #endif // !defined(GOLD_SYMTAB_H)