sym

package
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 Go to latest Published: Feb 10, 2020 License: BSD-3-Clause Imports: 6 Imported by: 0

Documentation

Index

Constants

This section is empty.

Variables

View Source 
var AbiSymKindToSymKind = [...]SymKind{
	Sxxx,
	STEXT,
	SRODATA,
	SNOPTRDATA,
	SDATA,
	SBSS,
	SNOPTRBSS,
	STLSBSS,
	SDWARFINFO,
	SDWARFRANGE,
	SDWARFLOC,
	SDWARFMISC,
}

AbiSymKindToSymKind maps values read from object files (which are of type cmd/internal/objabi.SymKind) to values of type SymKind.

View Source 
var ReadOnly = []SymKind{
	STYPE,
	SSTRING,
	SGOSTRING,
	SGOFUNC,
	SGCBITS,
	SRODATA,
	SFUNCTAB,
}

ReadOnly are the symbol kinds that form read-only sections. In some cases, if they will require relocations, they are transformed into rel-ro sections using relROMap.

View Source 
var RelROMap = map[SymKind]SymKind{
	STYPE:     STYPERELRO,
	SSTRING:   SSTRINGRELRO,
	SGOSTRING: SGOSTRINGRELRO,
	SGOFUNC:   SGOFUNCRELRO,
	SGCBITS:   SGCBITSRELRO,
	SRODATA:   SRODATARELRO,
	SFUNCTAB:  SFUNCTABRELRO,
}

RelROMap describes the transformation of read-only symbols to rel-ro symbols.

Functions

func RelocName 

func RelocName(arch *sys.Arch, r objabi.RelocType) string

Types

type Attribute 

type Attribute int32

Attribute is a set of common symbol attributes. 

const (
	// AttrDuplicateOK marks a symbol that can be present in multiple object
	// files.
	AttrDuplicateOK Attribute = 1 << iota
	// AttrExternal marks function symbols loaded from host object files.
	AttrExternal
	// AttrNoSplit marks functions that cannot split the stack; the linker
	// cares because it checks that there are no call chains of nosplit
	// functions that require more than StackLimit bytes (see
	// lib.go:dostkcheck)
	AttrNoSplit
	// AttrReachable marks symbols that are transitively referenced from the
	// entry points. Unreachable symbols are not written to the output.
	AttrReachable
	// AttrCgoExportDynamic and AttrCgoExportStatic mark symbols referenced
	// by directives written by cgo (in response to //export directives in
	// the source).
	AttrCgoExportDynamic
	AttrCgoExportStatic
	// AttrSpecial marks symbols that do not have their address (i.e. Value)
	// computed by the usual mechanism of data.go:dodata() &
	// data.go:address().
	AttrSpecial
	// AttrStackCheck is used by dostkcheck to only check each NoSplit
	// function's stack usage once.
	AttrStackCheck
	// AttrNotInSymbolTable marks symbols that are not written to the symbol table.
	AttrNotInSymbolTable
	// AttrOnList marks symbols that are on some list (such as the list of
	// all text symbols, or one of the lists of data symbols) and is
	// consulted to avoid bugs where a symbol is put on a list twice.
	AttrOnList
	// AttrLocal marks symbols that are only visible within the module
	// (executable or shared library) being linked. Only relevant when
	// dynamically linking Go code.
	AttrLocal
	// AttrReflectMethod marks certain methods from the reflect package that
	// can be used to call arbitrary methods. If no symbol with this bit set
	// is marked as reachable, more dead code elimination can be done.
	AttrReflectMethod
	// AttrMakeTypelink Amarks types that should be added to the typelink
	// table. See typelinks.go:typelinks().
	AttrMakeTypelink
	// AttrShared marks symbols compiled with the -shared option.
	AttrShared
	// AttrVisibilityHidden symbols are ELF symbols with
	// visibility set to STV_HIDDEN. They become local symbols in
	// the final executable. Only relevant when internally linking
	// on an ELF platform.
	AttrVisibilityHidden
	// AttrSubSymbol mostly means that the symbol appears on the Sub list of some
	// other symbol.  Unfortunately, it's not 100% reliable; at least, it's not set
	// correctly for the .TOC. symbol in Link.dodata.  Usually the Outer field of the
	// symbol points to the symbol whose list it is on, but that it is not set for the
	// symbols added to .windynamic in initdynimport in pe.go.
	//
	// TODO(mwhudson): fix the inconsistencies noticed above.
	//
	// Sub lists are used when loading host objects (sections from the host object
	// become regular linker symbols and symbols go on the Sub list of their section)
	// and for constructing the global offset table when internally linking a dynamic
	// executable.
	//
	// TODO(mwhudson): perhaps a better name for this is AttrNonGoSymbol.
	AttrSubSymbol
	// AttrContainer is set on text symbols that are present as the .Outer for some
	// other symbol.
	AttrContainer
)

func (Attribute) CgoExport 

func (a Attribute) CgoExport() bool

func (Attribute) CgoExportDynamic 

func (a Attribute) CgoExportDynamic() bool

func (Attribute) CgoExportStatic 

func (a Attribute) CgoExportStatic() bool

func (Attribute) Container 

func (a Attribute) Container() bool

func (Attribute) DuplicateOK 

func (a Attribute) DuplicateOK() bool

func (Attribute) External 

func (a Attribute) External() bool

func (Attribute) Local 

func (a Attribute) Local() bool
func (a Attribute) MakeTypelink() bool

func (Attribute) NoSplit 

func (a Attribute) NoSplit() bool

func (Attribute) NotInSymbolTable 

func (a Attribute) NotInSymbolTable() bool

func (Attribute) OnList 

func (a Attribute) OnList() bool

func (Attribute) Reachable 

func (a Attribute) Reachable() bool

func (Attribute) ReflectMethod 

func (a Attribute) ReflectMethod() bool

func (*Attribute) Set 

func (a *Attribute) Set(flag Attribute, value bool)

func (Attribute) Shared 

func (a Attribute) Shared() bool

func (Attribute) Special 

func (a Attribute) Special() bool

func (Attribute) StackCheck 

func (a Attribute) StackCheck() bool

func (Attribute) SubSymbol 

func (a Attribute) SubSymbol() bool

func (Attribute) VisibilityHidden 

func (a Attribute) VisibilityHidden() bool

type Auto 

type Auto struct {
	Asym    *Symbol
	Gotype  *Symbol
	Aoffset int32
	Name    int16
}

type FuncInfo 

type FuncInfo struct {
	Args        int32
	Locals      int32
	Autom       []Auto
	Pcsp        Pcdata
	Pcfile      Pcdata
	Pcline      Pcdata
	Pcinline    Pcdata
	Pcdata      []Pcdata
	Funcdata    []*Symbol
	Funcdataoff []int64
	File        []*Symbol
	InlTree     []InlinedCall
}

type InlinedCall 

type InlinedCall struct {
	Parent int32   // index of parent in InlTree
	File   *Symbol // file of the inlined call
	Line   int32   // line number of the inlined call
	Func   *Symbol // function that was inlined
}

InlinedCall is a node in a local inlining tree (FuncInfo.InlTree).

type Library 

type Library struct {
	Objref        string
	Srcref        string
	File          string
	Pkg           string
	Shlib         string
	Hash          string
	ImportStrings []string
	Imports       []*Library
	Textp         []*Symbol // text symbols defined in this library
	DupTextSyms   []*Symbol // dupok text symbols defined in this library
	Main          bool
	Safe          bool
}

func (Library) String 

func (l Library) String() string

type Pcdata 

type Pcdata struct {
	P []byte
}

type Reloc 

type Reloc struct {
	Off     int32            // offset to rewrite
	Siz     uint8            // number of bytes to rewrite, 1, 2, or 4
	Done    bool             // set to true when relocation is complete
	Variant RelocVariant     // variation on Type
	Type    objabi.RelocType // the relocation type
	Add     int64            // addend
	Xadd    int64            // addend passed to external linker
	Sym     *Symbol          // symbol the relocation addresses
	Xsym    *Symbol          // symbol passed to external linker
}

Reloc is a relocation.

The typical Reloc rewrites part of a symbol at offset Off to address Sym. A Reloc is stored in a slice on the Symbol it rewrites.

Relocations are generated by the compiler as the type cmd/internal/obj.Reloc, which is encoded into the object file wire format and decoded by the linker into this type. A separate type is used to hold linker-specific state about the relocation.

Some relocations are created by cmd/link.

type RelocByOff 

type RelocByOff []Reloc

RelocByOff implements sort.Interface for sorting relocations by offset.

func (RelocByOff) Len 

func (x RelocByOff) Len() int

func (RelocByOff) Less 

func (x RelocByOff) Less(i, j int) bool

func (RelocByOff) Swap 

func (x RelocByOff) Swap(i, j int)

type RelocVariant 

type RelocVariant uint8

RelocVariant is a linker-internal variation on a relocation. 

const (
	RV_NONE RelocVariant = iota
	RV_POWER_LO
	RV_POWER_HI
	RV_POWER_HA
	RV_POWER_DS

	// RV_390_DBL is a s390x-specific relocation variant that indicates that
	// the value to be placed into the relocatable field should first be
	// divided by 2.
	RV_390_DBL

	RV_CHECK_OVERFLOW RelocVariant = 1 << 7
	RV_TYPE_MASK      RelocVariant = RV_CHECK_OVERFLOW - 1
)

type Section 

type Section struct {
	Rwx     uint8
	Extnum  int16
	Align   int32
	Name    string
	Vaddr   uint64
	Length  uint64
	Seg     *Segment
	Elfsect interface{} // an *ld.ElfShdr
	Reloff  uint64
	Rellen  uint64
}

type Segment 

type Segment struct {
	Rwx      uint8  // permission as usual unix bits (5 = r-x etc)
	Vaddr    uint64 // virtual address
	Length   uint64 // length in memory
	Fileoff  uint64 // file offset
	Filelen  uint64 // length on disk
	Sections []*Section
}

type SymKind 

type SymKind uint8

A SymKind describes the kind of memory represented by a symbol. 

const (
	Sxxx SymKind = iota
	STEXT
	SELFRXSECT

	// Read-only sections.
	STYPE
	SSTRING
	SGOSTRING
	SGOFUNC
	SGCBITS
	SRODATA
	SFUNCTAB

	SELFROSECT
	SMACHOPLT

	// Read-only sections with relocations.
	//
	// Types STYPE-SFUNCTAB above are written to the .rodata section by default.
	// When linking a shared object, some conceptually "read only" types need to
	// be written to by relocations and putting them in a section called
	// ".rodata" interacts poorly with the system linkers. The GNU linkers
	// support this situation by arranging for sections of the name
	// ".data.rel.ro.XXX" to be mprotected read only by the dynamic linker after
	// relocations have applied, so when the Go linker is creating a shared
	// object it checks all objects of the above types and bumps any object that
	// has a relocation to it to the corresponding type below, which are then
	// written to sections with appropriate magic names.
	STYPERELRO
	SSTRINGRELRO
	SGOSTRINGRELRO
	SGOFUNCRELRO
	SGCBITSRELRO
	SRODATARELRO
	SFUNCTABRELRO

	// Part of .data.rel.ro if it exists, otherwise part of .rodata.
	STYPELINK
	SITABLINK
	SSYMTAB
	SPCLNTAB

	// Writable sections.
	SELFSECT
	SMACHO
	SMACHOGOT
	SWINDOWS
	SELFGOT
	SNOPTRDATA
	SINITARR
	SDATA
	SBSS
	SNOPTRBSS
	STLSBSS
	SXREF
	SMACHOSYMSTR
	SMACHOSYMTAB
	SMACHOINDIRECTPLT
	SMACHOINDIRECTGOT
	SFILEPATH
	SCONST
	SDYNIMPORT
	SHOSTOBJ

	// Sections for debugging information
	SDWARFSECT
	SDWARFINFO
	SDWARFRANGE
	SDWARFLOC
	SDWARFMISC // Not really a section; informs/affects other DWARF section generation
)

Defined SymKind values.

TODO(rsc): Give idiomatic Go names.

func (SymKind) String 

func (i SymKind) String() string

type Symbol 

type Symbol struct {
	Name        string
	Extname     string
	Type        SymKind
	Version     int16
	Attr        Attribute
	Localentry  uint8
	Dynid       int32
	Plt         int32
	Got         int32
	Align       int32
	Elfsym      int32
	LocalElfsym int32
	Value       int64
	Size        int64
	// ElfType is set for symbols read from shared libraries by ldshlibsyms. It
	// is not set for symbols defined by the packages being linked or by symbols
	// read by ldelf (and so is left as elf.STT_NOTYPE).
	ElfType elf.SymType
	Sub     *Symbol
	Outer   *Symbol
	Gotype  *Symbol
	File    string

	Sect     *Section
	FuncInfo *FuncInfo
	Lib      *Library // Package defining this symbol
	// P contains the raw symbol data.
	P []byte
	R []Reloc
	// contains filtered or unexported fields
}

Symbol is an entry in the symbol table.

func SortSub 

func SortSub(l *Symbol) *Symbol

SortSub sorts a linked-list (by Sub) of *Symbol by Value. Used for sub-symbols when loading host objects (see e.g. ldelf.go).

func (*Symbol) AddAddr 

func (s *Symbol) AddAddr(arch *sys.Arch, t *Symbol) int64

func (*Symbol) AddAddrPlus 

func (s *Symbol) AddAddrPlus(arch *sys.Arch, t *Symbol, add int64) int64

func (*Symbol) AddAddrPlus4 

func (s *Symbol) AddAddrPlus4(t *Symbol, add int64) int64

func (*Symbol) AddBytes 

func (s *Symbol) AddBytes(bytes []byte) int64

func (*Symbol) AddPCRelPlus 

func (s *Symbol) AddPCRelPlus(arch *sys.Arch, t *Symbol, add int64) int64

func (*Symbol) AddRel 

func (s *Symbol) AddRel() *Reloc

func (*Symbol) AddSize 

func (s *Symbol) AddSize(arch *sys.Arch, t *Symbol) int64

func (*Symbol) AddUint 

func (s *Symbol) AddUint(arch *sys.Arch, v uint64) int64

func (*Symbol) AddUint16 

func (s *Symbol) AddUint16(arch *sys.Arch, v uint16) int64

func (*Symbol) AddUint32 

func (s *Symbol) AddUint32(arch *sys.Arch, v uint32) int64

func (*Symbol) AddUint64 

func (s *Symbol) AddUint64(arch *sys.Arch, v uint64) int64

func (*Symbol) AddUint8 

func (s *Symbol) AddUint8(v uint8) int64

func (*Symbol) AddUintXX 

func (s *Symbol) AddUintXX(arch *sys.Arch, v uint64, wid int) int64

func (*Symbol) Dynimplib 

func (s *Symbol) Dynimplib() string

func (*Symbol) Dynimpvers 

func (s *Symbol) Dynimpvers() string

func (*Symbol) ElfsymForReloc 

func (s *Symbol) ElfsymForReloc() int32

func (*Symbol) Grow 

func (s *Symbol) Grow(siz int64)

func (*Symbol) Len 

func (s *Symbol) Len() int64

func (*Symbol) ResetDyninfo 

func (s *Symbol) ResetDyninfo()

func (*Symbol) SetAddr 

func (s *Symbol) SetAddr(arch *sys.Arch, off int64, t *Symbol) int64

func (*Symbol) SetAddrPlus 

func (s *Symbol) SetAddrPlus(arch *sys.Arch, off int64, t *Symbol, add int64) int64

func (*Symbol) SetDynimplib 

func (s *Symbol) SetDynimplib(lib string)

func (*Symbol) SetDynimpvers 

func (s *Symbol) SetDynimpvers(vers string)

func (*Symbol) SetUint 

func (s *Symbol) SetUint(arch *sys.Arch, r int64, v uint64) int64

func (*Symbol) SetUint32 

func (s *Symbol) SetUint32(arch *sys.Arch, r int64, v uint32) int64

func (*Symbol) SetUint8 

func (s *Symbol) SetUint8(arch *sys.Arch, r int64, v uint8) int64

func (*Symbol) String 

func (s *Symbol) String() string

type Symbols 

type Symbols struct {
	Allsym []*Symbol
	// contains filtered or unexported fields
}

func NewSymbols 

func NewSymbols() *Symbols

func (*Symbols) IncVersion 

func (syms *Symbols) IncVersion() int

Allocate a new version (i.e. symbol namespace).

func (*Symbols) Lookup 

func (syms *Symbols) Lookup(name string, v int) *Symbol

Look up the symbol with the given name and version, creating the symbol if it is not found.

func (*Symbols) Newsym 

func (syms *Symbols) Newsym(name string, v int) *Symbol

func (*Symbols) ROLookup 

func (syms *Symbols) ROLookup(name string, v int) *Symbol

Look up the symbol with the given name and version, returning nil if it is not found.

func (*Symbols) Rename 

func (syms *Symbols) Rename(old, new string, v int)

Rename renames a symbol.

Source Files

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