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Package sym

import "cmd/link/internal/sym"
Overview
Index

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Constants

const (
    SymVerABI0        = 0
    SymVerABIInternal = 1
    SymVerStatic      = 10 // Minimum version used by static (file-local) syms
)

Variables

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

var AbiSymKindToSymKind = [...]SymKind{
    Sxxx,
    STEXT,
    SRODATA,
    SNOPTRDATA,
    SDATA,
    SBSS,
    SNOPTRBSS,
    STLSBSS,
    SDWARFCUINFO,
    SDWARFCONST,
    SDWARFFCN,
    SDWARFABSFCN,
    SDWARFTYPE,
    SDWARFVAR,
    SDWARFRANGE,
    SDWARFLOC,
    SDWARFLINES,
    SABIALIAS,
    SLIBFUZZER_EXTRA_COUNTER,
}

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. 

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

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

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

func ABIToVersion 

func ABIToVersion(abi obj.ABI) int

func RelocName 

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

func VersionToABI 

func VersionToABI(v int) (obj.ABI, bool)

type CompilationUnit

A CompilationUnit represents a set of source files that are compiled together. Since all Go sources in a Go package are compiled together, there's one CompilationUnit per package that represents all Go sources in that package, plus one for each assembly file.

Equivalently, there's one CompilationUnit per object file in each Library loaded by the linker.

These are used for both DWARF and pclntab generation. 

type CompilationUnit struct {
    Lib       *Library      // Our library
    PclnIndex int           // Index of this CU in pclntab
    PCs       []dwarf.Range // PC ranges, relative to Textp[0]
    DWInfo    *dwarf.DWDie  // CU root DIE
    FileTable []string      // The file table used in this compilation unit.

    Consts    LoaderSym   // Package constants DIEs
    FuncDIEs  []LoaderSym // Function DIE subtrees
    VarDIEs   []LoaderSym // Global variable DIEs
    AbsFnDIEs []LoaderSym // Abstract function DIE subtrees
    RangeSyms []LoaderSym // Symbols for debug_range
    Textp     []LoaderSym // Text symbols in this CU
}

type Library 

type Library struct {
    Objref      string
    Srcref      string
    File        string
    Pkg         string
    Shlib       string
    Fingerprint goobj.FingerprintType
    Autolib     []goobj.ImportedPkg
    Imports     []*Library
    Main        bool
    Units       []*CompilationUnit

    Textp       []LoaderSym // text syms defined in this library
    DupTextSyms []LoaderSym // dupok text syms defined in this library
}

func (Library) String 

func (l Library) String() string

type LoaderSym

LoaderSym holds a loader.Sym value. We can't refer to this type from the sym package since loader imports sym. 

type LoaderSym int

type RelocVariant

RelocVariant is a linker-internal variation on a relocation. 

type RelocVariant uint8
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
    // Relcount is the number of *host* relocations applied to this section
    // (when external linking).
    // Incremented atomically on multiple goroutines.
    // Note: this may differ from number of Go relocations, as one Go relocation
    // may turn into multiple host relocations.
    Relcount uint32
    Sym      LoaderSym // symbol for the section, if any
    Index    uint16    // each section has a unique index, used internally
}

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

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

type SymKind uint8

Defined SymKind values.

TODO(rsc): Give idiomatic Go names. 

const (
    Sxxx SymKind = iota
    STEXT
    SELFRXSECT
    SMACHOPLT

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

    SELFROSECT

    // 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.
    SFirstWritable
    SBUILDINFO
    SELFSECT
    SMACHO
    SMACHOGOT
    SWINDOWS
    SELFGOT
    SNOPTRDATA
    SINITARR
    SDATA
    SXCOFFTOC
    SBSS
    SNOPTRBSS
    SLIBFUZZER_EXTRA_COUNTER
    STLSBSS
    SXREF
    SMACHOSYMSTR
    SMACHOSYMTAB
    SMACHOINDIRECTPLT
    SMACHOINDIRECTGOT
    SFILEPATH
    SDYNIMPORT
    SHOSTOBJ
    SUNDEFEXT // Undefined symbol for resolution by external linker

    // Sections for debugging information
    SDWARFSECT
    // DWARF symbol types
    SDWARFCUINFO
    SDWARFCONST
    SDWARFFCN
    SDWARFABSFCN
    SDWARFTYPE
    SDWARFVAR
    SDWARFRANGE
    SDWARFLOC
    SDWARFLINES

    // ABI aliases (these never appear in the output)
    SABIALIAS
)

func (SymKind) IsData 

func (t SymKind) IsData() bool

IsData returns true if the type is a data type.

func (SymKind) String 

func (i SymKind) String() string