link.go

// Derived from Inferno utils/6l/l.h and related files.
// http://code.google.com/p/inferno-os/source/browse/utils/6l/l.h
//
//	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
//	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
//	Portions Copyright © 1997-1999 Vita Nuova Limited
//	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
//	Portions Copyright © 2004,2006 Bruce Ellis
//	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
//	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
//	Portions Copyright © 2009 The Go Authors.  All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package ld

import (
	"cmd/internal/obj"
	"debug/elf"
	"encoding/binary"
	"fmt"
)

type LSym struct {
	Name        string
	Extname     string
	Type        int16
	Version     int16
	Attr        Attribute
	Localentry  uint8
	Dynid       int32
	Plt         int32
	Got         int32
	Align       int32
	Elfsym      int32
	LocalElfsym int32
	Args        int32
	Locals      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
	Next        *LSym
	Sub         *LSym
	Outer       *LSym
	Gotype      *LSym
	Reachparent *LSym
	File        string
	Dynimplib   string
	Dynimpvers  string
	Sect        *Section
	Autom       []Auto
	Pcln        *Pcln
	P           []byte
	R           []Reloc
}

func (s *LSym) String() string {
	if s.Version == 0 {
		return s.Name
	}
	return fmt.Sprintf("%s<%d>", s.Name, s.Version)
}

func (s *LSym) ElfsymForReloc() int32 {
	// If putelfsym created a local version of this symbol, use that in all
	// relocations.
	if s.LocalElfsym != 0 {
		return s.LocalElfsym
	} else {
		return s.Elfsym
	}
}

// Attribute is a set of common symbol attributes.
type Attribute int16

const (
	AttrDuplicateOK Attribute = 1 << iota
	AttrExternal
	AttrNoSplit
	AttrReachable
	AttrCgoExportDynamic
	AttrCgoExportStatic
	AttrSpecial
	AttrStackCheck
	AttrHidden
	AttrOnList
	AttrLocal
	AttrReflectMethod
)

func (a Attribute) DuplicateOK() bool      { return a&AttrDuplicateOK != 0 }
func (a Attribute) External() bool         { return a&AttrExternal != 0 }
func (a Attribute) NoSplit() bool          { return a&AttrNoSplit != 0 }
func (a Attribute) Reachable() bool        { return a&AttrReachable != 0 }
func (a Attribute) CgoExportDynamic() bool { return a&AttrCgoExportDynamic != 0 }
func (a Attribute) CgoExportStatic() bool  { return a&AttrCgoExportStatic != 0 }
func (a Attribute) Special() bool          { return a&AttrSpecial != 0 }
func (a Attribute) StackCheck() bool       { return a&AttrStackCheck != 0 }
func (a Attribute) Hidden() bool           { return a&AttrHidden != 0 }
func (a Attribute) OnList() bool           { return a&AttrOnList != 0 }
func (a Attribute) Local() bool            { return a&AttrLocal != 0 }
func (a Attribute) ReflectMethod() bool    { return a&AttrReflectMethod != 0 }

func (a Attribute) CgoExport() bool {
	return a.CgoExportDynamic() || a.CgoExportStatic()
}

func (a *Attribute) Set(flag Attribute, value bool) {
	if value {
		*a |= flag
	} else {
		*a &^= flag
	}
}

type Reloc struct {
	Off     int32
	Siz     uint8
	Done    uint8
	Type    int32
	Variant int32
	Add     int64
	Xadd    int64
	Sym     *LSym
	Xsym    *LSym
}

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

type Shlib struct {
	Path             string
	Hash             []byte
	Deps             []string
	File             *elf.File
	gcdata_addresses map[*LSym]uint64
}

type Link struct {
	Thechar   int32
	Thestring string
	Goarm     int32
	Headtype  int
	Arch      *LinkArch
	Debugvlog int32
	Bso       *obj.Biobuf
	Windows   int32
	Goroot    string

	// Symbol lookup based on name and indexed by version.
	Hash []map[string]*LSym

	Allsym     []*LSym
	Tlsg       *LSym
	Libdir     []string
	Library    []*Library
	Shlibs     []Shlib
	Tlsoffset  int
	Diag       func(string, ...interface{})
	Cursym     *LSym
	Version    int
	Textp      *LSym
	Etextp     *LSym
	Nhistfile  int32
	Filesyms   *LSym
	Moduledata *LSym
	LSymBatch  []LSym
}

// The smallest possible offset from the hardware stack pointer to a local
// variable on the stack. Architectures that use a link register save its value
// on the stack in the function prologue and so always have a pointer between
// the hardware stack pointer and the local variable area.
func (ctxt *Link) FixedFrameSize() int64 {
	switch ctxt.Arch.Thechar {
	case '6', '8':
		return 0
	case '9':
		// PIC code on ppc64le requires 32 bytes of stack, and it's easier to
		// just use that much stack always on ppc64x.
		return int64(4 * ctxt.Arch.Ptrsize)
	default:
		return int64(ctxt.Arch.Ptrsize)
	}
}

func (l *Link) IncVersion() {
	l.Version++
	l.Hash = append(l.Hash, make(map[string]*LSym))
}

type LinkArch struct {
	ByteOrder binary.ByteOrder
	Name      string
	Thechar   int
	Minlc     int
	Ptrsize   int
	Regsize   int
}

type Library struct {
	Objref string
	Srcref string
	File   string
	Pkg    string
	Shlib  string
	hash   []byte
}

type Pcln struct {
	Pcsp        Pcdata
	Pcfile      Pcdata
	Pcline      Pcdata
	Pcdata      []Pcdata
	Funcdata    []*LSym
	Funcdataoff []int64
	File        []*LSym
}

type Pcdata struct {
	P []byte
}

type Pciter struct {
	d       Pcdata
	p       []byte
	pc      uint32
	nextpc  uint32
	pcscale uint32
	value   int32
	start   int
	done    int
}

// Reloc.variant
const (
	RV_NONE = 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 = 1 << 8
	RV_TYPE_MASK      = RV_CHECK_OVERFLOW - 1
)

// Pcdata iterator.
//	for(pciterinit(ctxt, &it, &pcd); !it.done; pciternext(&it)) { it.value holds in [it.pc, it.nextpc) }

// Link holds the context for writing object code from a compiler
// to be linker input or for reading that input into the linker.

// LinkArch is the definition of a single architecture.

const (
	LinkAuto = 0 + iota
	LinkInternal
	LinkExternal
)