-
Keith Randall authored
Generic function symbols sometimes have % in them, like: main.B2[%2eshape.string_0].m2·f Which confuses this code because it doesn't esacpe % when using this string as a format string, instead of a format argument. Or could we get rid of the . -> %2e rewrite somehow? I think it comes from LinkString. Change-Id: I3275501f44cf30485e9d4577e0dfa77996d4939e Reviewed-on: https://go-review.googlesource.com/c/go/+/357837 Trust: Keith Randall <khr@golang.org> Trust: Dan Scales <danscales@google.com> Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by:Dan Scales <danscales@google.com>
Keith Randall authoredGeneric function symbols sometimes have % in them, like: main.B2[%2eshape.string_0].m2·f Which confuses this code because it doesn't esacpe % when using this string as a format string, instead of a format argument. Or could we get rid of the . -> %2e rewrite somehow? I think it comes from LinkString. Change-Id: I3275501f44cf30485e9d4577e0dfa77996d4939e Reviewed-on: https://go-review.googlesource.com/c/go/+/357837 Trust: Keith Randall <khr@golang.org> Trust: Dan Scales <danscales@google.com> Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by:
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loader.go 78.87 KiB
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package loader
import (
"bytes"
"cmd/internal/bio"
"cmd/internal/goobj"
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/sys"
"cmd/link/internal/sym"
"debug/elf"
"fmt"
"log"
"math/bits"
"os"
"sort"
"strings"
)
var _ = fmt.Print
// Sym encapsulates a global symbol index, used to identify a specific
// Go symbol. The 0-valued Sym is corresponds to an invalid symbol.
type Sym int
// Relocs encapsulates the set of relocations on a given symbol; an
// instance of this type is returned by the Loader Relocs() method.
type Relocs struct {
rs []goobj.Reloc
li uint32 // local index of symbol whose relocs we're examining
r *oReader // object reader for containing package
l *Loader // loader
}
// ExtReloc contains the payload for an external relocation.
type ExtReloc struct {
Xsym Sym
Xadd int64
Type objabi.RelocType
Size uint8
}
// Reloc holds a "handle" to access a relocation record from an
// object file.
type Reloc struct {
*goobj.Reloc
r *oReader
l *Loader
}
func (rel Reloc) Type() objabi.RelocType { return objabi.RelocType(rel.Reloc.Type()) &^ objabi.R_WEAK }
func (rel Reloc) Weak() bool { return objabi.RelocType(rel.Reloc.Type())&objabi.R_WEAK != 0 }
func (rel Reloc) SetType(t objabi.RelocType) { rel.Reloc.SetType(uint16(t)) }
func (rel Reloc) Sym() Sym { return rel.l.resolve(rel.r, rel.Reloc.Sym()) }
func (rel Reloc) SetSym(s Sym) { rel.Reloc.SetSym(goobj.SymRef{PkgIdx: 0, SymIdx: uint32(s)}) }
func (rel Reloc) IsMarker() bool { return rel.Siz() == 0 }
// Aux holds a "handle" to access an aux symbol record from an
// object file.
type Aux struct {
*goobj.Aux
r *oReader
l *Loader
}
func (a Aux) Sym() Sym { return a.l.resolve(a.r, a.Aux.Sym()) }
// oReader is a wrapper type of obj.Reader, along with some
// extra information.
type oReader struct {
*goobj.Reader
unit *sym.CompilationUnit
version int // version of static symbol
flags uint32 // read from object file
pkgprefix string
syms []Sym // Sym's global index, indexed by local index
pkg []uint32 // indices of referenced package by PkgIdx (index into loader.objs array)
ndef int // cache goobj.Reader.NSym()
nhashed64def int // cache goobj.Reader.NHashed64Def()
nhasheddef int // cache goobj.Reader.NHashedDef()
objidx uint32 // index of this reader in the objs slice
}
// Total number of defined symbols (package symbols, hashed symbols, and
// non-package symbols).
func (r *oReader) NAlldef() int { return r.ndef + r.nhashed64def + r.nhasheddef + r.NNonpkgdef() }
type objIdx struct {
r *oReader
i Sym // start index
}
// objSym represents a symbol in an object file. It is a tuple of
// the object and the symbol's local index.
// For external symbols, objidx is the index of l.extReader (extObj),
// s is its index into the payload array.
// {0, 0} represents the nil symbol.
type objSym struct {
objidx uint32 // index of the object (in l.objs array)
s uint32 // local index
}
type nameVer struct {
name string
v int
}
type Bitmap []uint32
// set the i-th bit.
func (bm Bitmap) Set(i Sym) {
n, r := uint(i)/32, uint(i)%32
bm[n] |= 1 << r
}
// unset the i-th bit.
func (bm Bitmap) Unset(i Sym) {
n, r := uint(i)/32, uint(i)%32
bm[n] &^= (1 << r)
}
// whether the i-th bit is set.
func (bm Bitmap) Has(i Sym) bool {
n, r := uint(i)/32, uint(i)%32
return bm[n]&(1<<r) != 0
}
// return current length of bitmap in bits.
func (bm Bitmap) Len() int {
return len(bm) * 32
}
// return the number of bits set.
func (bm Bitmap) Count() int {
s := 0 for _, x := range bm {
s += bits.OnesCount32(x)
}
return s
}
func MakeBitmap(n int) Bitmap {
return make(Bitmap, (n+31)/32)
}
// growBitmap insures that the specified bitmap has enough capacity,
// reallocating (doubling the size) if needed.
func growBitmap(reqLen int, b Bitmap) Bitmap {
curLen := b.Len()
if reqLen > curLen {
b = append(b, MakeBitmap(reqLen+1-curLen)...)
}
return b
}
type symAndSize struct {
sym Sym
size uint32
}
// A Loader loads new object files and resolves indexed symbol references.
//
// Notes on the layout of global symbol index space:
//
// - Go object files are read before host object files; each Go object
// read adds its defined package symbols to the global index space.
// Nonpackage symbols are not yet added.
//
// - In loader.LoadNonpkgSyms, add non-package defined symbols and
// references in all object files to the global index space.
//
// - Host object file loading happens; the host object loader does a
// name/version lookup for each symbol it finds; this can wind up
// extending the external symbol index space range. The host object
// loader stores symbol payloads in loader.payloads using SymbolBuilder.
//
// - Each symbol gets a unique global index. For duplicated and
// overwriting/overwritten symbols, the second (or later) appearance
// of the symbol gets the same global index as the first appearance.
type Loader struct {
start map[*oReader]Sym // map from object file to its start index
objs []objIdx // sorted by start index (i.e. objIdx.i)
extStart Sym // from this index on, the symbols are externally defined
builtinSyms []Sym // global index of builtin symbols
objSyms []objSym // global index mapping to local index
symsByName [2]map[string]Sym // map symbol name to index, two maps are for ABI0 and ABIInternal
extStaticSyms map[nameVer]Sym // externally defined static symbols, keyed by name
extReader *oReader // a dummy oReader, for external symbols
payloadBatch []extSymPayload
payloads []*extSymPayload // contents of linker-materialized external syms
values []int64 // symbol values, indexed by global sym index
sects []*sym.Section // sections
symSects []uint16 // symbol's section, index to sects array
align []uint8 // symbol 2^N alignment, indexed by global index
deferReturnTramp map[Sym]bool // whether the symbol is a trampoline of a deferreturn call
objByPkg map[string]uint32 // map package path to the index of its Go object reader
anonVersion int // most recently assigned ext static sym pseudo-version
// Bitmaps and other side structures used to store data used to store
// symbol flags/attributes; these are to be accessed via the
// corresponding loader "AttrXXX" and "SetAttrXXX" methods. Please
// visit the comments on these methods for more details on the
// semantics / interpretation of the specific flags or attribute.
attrReachable Bitmap // reachable symbols, indexed by global index
attrOnList Bitmap // "on list" symbols, indexed by global index
attrLocal Bitmap // "local" symbols, indexed by global index
attrNotInSymbolTable Bitmap // "not in symtab" symbols, indexed by global idx
attrUsedInIface Bitmap // "used in interface" symbols, indexed by global idx
attrVisibilityHidden Bitmap // hidden symbols, indexed by ext sym index
attrDuplicateOK Bitmap // dupOK symbols, indexed by ext sym index
attrShared Bitmap // shared symbols, indexed by ext sym index
attrExternal Bitmap // external symbols, indexed by ext sym index
attrReadOnly map[Sym]bool // readonly data for this sym
attrSpecial map[Sym]struct{} // "special" frame symbols
attrCgoExportDynamic map[Sym]struct{} // "cgo_export_dynamic" symbols
attrCgoExportStatic map[Sym]struct{} // "cgo_export_static" symbols
generatedSyms map[Sym]struct{} // symbols that generate their content
// Outer and Sub relations for symbols.
// TODO: figure out whether it's more efficient to just have these
// as fields on extSymPayload (note that this won't be a viable
// strategy if somewhere in the linker we set sub/outer for a
// non-external sym).
outer map[Sym]Sym
sub map[Sym]Sym
dynimplib map[Sym]string // stores Dynimplib symbol attribute
dynimpvers map[Sym]string // stores Dynimpvers symbol attribute
localentry map[Sym]uint8 // stores Localentry symbol attribute
extname map[Sym]string // stores Extname symbol attribute
elfType map[Sym]elf.SymType // stores elf type symbol property
elfSym map[Sym]int32 // stores elf sym symbol property
localElfSym map[Sym]int32 // stores "local" elf sym symbol property
symPkg map[Sym]string // stores package for symbol, or library for shlib-derived syms
plt map[Sym]int32 // stores dynimport for pe objects
got map[Sym]int32 // stores got for pe objects
dynid map[Sym]int32 // stores Dynid for symbol
relocVariant map[relocId]sym.RelocVariant // stores variant relocs
// Used to implement field tracking; created during deadcode if
// field tracking is enabled. Reachparent[K] contains the index of
// the symbol that triggered the marking of symbol K as live.
Reachparent []Sym
// CgoExports records cgo-exported symbols by SymName.
CgoExports map[string]Sym
flags uint32
hasUnknownPkgPath bool // if any Go object has unknown package path
strictDupMsgs int // number of strict-dup warning/errors, when FlagStrictDups is enabled
elfsetstring elfsetstringFunc
errorReporter *ErrorReporter
npkgsyms int // number of package symbols, for accounting
nhashedsyms int // number of hashed symbols, for accounting
}
const (
pkgDef = iota
hashed64Def
hashedDef nonPkgDef
nonPkgRef
)
// objidx
const (
nilObj = iota
extObj
goObjStart
)
type elfsetstringFunc func(str string, off int)
// extSymPayload holds the payload (data + relocations) for linker-synthesized
// external symbols (note that symbol value is stored in a separate slice).
type extSymPayload struct {
name string // TODO: would this be better as offset into str table?
size int64
ver int
kind sym.SymKind
objidx uint32 // index of original object if sym made by cloneToExternal
relocs []goobj.Reloc
data []byte
auxs []goobj.Aux
}
const (
// Loader.flags
FlagStrictDups = 1 << iota
)
func NewLoader(flags uint32, elfsetstring elfsetstringFunc, reporter *ErrorReporter) *Loader {
nbuiltin := goobj.NBuiltin()
extReader := &oReader{objidx: extObj}
ldr := &Loader{
start: make(map[*oReader]Sym),
objs: []objIdx{{}, {extReader, 0}}, // reserve index 0 for nil symbol, 1 for external symbols
objSyms: make([]objSym, 1, 1), // This will get overwritten later.
extReader: extReader,
symsByName: [2]map[string]Sym{make(map[string]Sym, 80000), make(map[string]Sym, 50000)}, // preallocate ~2MB for ABI0 and ~1MB for ABI1 symbols
objByPkg: make(map[string]uint32),
outer: make(map[Sym]Sym),
sub: make(map[Sym]Sym),
dynimplib: make(map[Sym]string),
dynimpvers: make(map[Sym]string),
localentry: make(map[Sym]uint8),
extname: make(map[Sym]string),
attrReadOnly: make(map[Sym]bool),
elfType: make(map[Sym]elf.SymType),
elfSym: make(map[Sym]int32),
localElfSym: make(map[Sym]int32),
symPkg: make(map[Sym]string),
plt: make(map[Sym]int32),
got: make(map[Sym]int32),
dynid: make(map[Sym]int32),
attrSpecial: make(map[Sym]struct{}),
attrCgoExportDynamic: make(map[Sym]struct{}),
attrCgoExportStatic: make(map[Sym]struct{}),
generatedSyms: make(map[Sym]struct{}),
deferReturnTramp: make(map[Sym]bool),
extStaticSyms: make(map[nameVer]Sym),
builtinSyms: make([]Sym, nbuiltin),
flags: flags,
elfsetstring: elfsetstring,
errorReporter: reporter,
sects: []*sym.Section{nil}, // reserve index 0 for nil section
}
reporter.ldr = ldr
return ldr
}
// Add object file r, return the start index.
func (l *Loader) addObj(pkg string, r *oReader) Sym {
if _, ok := l.start[r]; ok {
panic("already added")
}
pkg = objabi.PathToPrefix(pkg) // the object file contains escaped package path
if _, ok := l.objByPkg[pkg]; !ok {
l.objByPkg[pkg] = r.objidx
}
i := Sym(len(l.objSyms))
l.start[r] = i
l.objs = append(l.objs, objIdx{r, i})
if r.NeedNameExpansion() && !r.FromAssembly() {
l.hasUnknownPkgPath = true
}
return i
}
// Add a symbol from an object file, return the global index.
// If the symbol already exist, it returns the index of that symbol.
func (st *loadState) addSym(name string, ver int, r *oReader, li uint32, kind int, osym *goobj.Sym) Sym {
l := st.l
if l.extStart != 0 {
panic("addSym called after external symbol is created")
}
i := Sym(len(l.objSyms))
addToGlobal := func() {
l.objSyms = append(l.objSyms, objSym{r.objidx, li})
}
if name == "" && kind != hashed64Def && kind != hashedDef {
addToGlobal()
return i // unnamed aux symbol
}
if ver == r.version {
// Static symbol. Add its global index but don't
// add to name lookup table, as it cannot be
// referenced by name.
addToGlobal()
return i
}
switch kind {
case pkgDef:
// Defined package symbols cannot be dup to each other.
// We load all the package symbols first, so we don't need
// to check dup here.
// We still add it to the lookup table, as it may still be
// referenced by name (e.g. through linkname).
l.symsByName[ver][name] = i
addToGlobal()
return i
case hashed64Def, hashedDef:
// Hashed (content-addressable) symbol. Check the hash
// but don't add to name lookup table, as they are not
// referenced by name. Also no need to do overwriting
// check, as same hash indicates same content.
var checkHash func() (symAndSize, bool)
var addToHashMap func(symAndSize)
var h64 uint64 // only used for hashed64Def
var h *goobj.HashType // only used for hashedDef
if kind == hashed64Def {
checkHash = func() (symAndSize, bool) {
h64 = r.Hash64(li - uint32(r.ndef))
s, existed := st.hashed64Syms[h64]
return s, existed
}
addToHashMap = func(ss symAndSize) { st.hashed64Syms[h64] = ss }
} else {
checkHash = func() (symAndSize, bool) {
h = r.Hash(li - uint32(r.ndef+r.nhashed64def)) s, existed := st.hashedSyms[*h]
return s, existed
}
addToHashMap = func(ss symAndSize) { st.hashedSyms[*h] = ss }
}
siz := osym.Siz()
if s, existed := checkHash(); existed {
// The content hash is built from symbol data and relocations. In the
// object file, the symbol data may not always contain trailing zeros,
// e.g. for [5]int{1,2,3} and [100]int{1,2,3}, the data is same
// (although the size is different).
// Also, for short symbols, the content hash is the identity function of
// the 8 bytes, and trailing zeros doesn't change the hash value, e.g.
// hash("A") == hash("A\0\0\0").
// So when two symbols have the same hash, we need to use the one with
// larger size.
if siz > s.size {
// New symbol has larger size, use the new one. Rewrite the index mapping.
l.objSyms[s.sym] = objSym{r.objidx, li}
addToHashMap(symAndSize{s.sym, siz})
}
return s.sym
}
addToHashMap(symAndSize{i, siz})
addToGlobal()
return i
}
// Non-package (named) symbol. Check if it already exists.
oldi, existed := l.symsByName[ver][name]
if !existed {
l.symsByName[ver][name] = i
addToGlobal()
return i
}
// symbol already exists
if osym.Dupok() {
if l.flags&FlagStrictDups != 0 {
l.checkdup(name, r, li, oldi)
}
// Fix for issue #47185 -- given two dupok symbols with
// different sizes, favor symbol with larger size. See
// also issue #46653.
szdup := l.SymSize(oldi)
sz := int64(r.Sym(li).Siz())
if szdup < sz {
// new symbol overwrites old symbol.
l.objSyms[oldi] = objSym{r.objidx, li}
}
return oldi
}
oldr, oldli := l.toLocal(oldi)
oldsym := oldr.Sym(oldli)
if oldsym.Dupok() {
return oldi
}
overwrite := r.DataSize(li) != 0
if overwrite {
// new symbol overwrites old symbol.
oldtyp := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type())]
if !(oldtyp.IsData() && oldr.DataSize(oldli) == 0) {
log.Fatalf("duplicated definition of symbol %s, from %s and %s", name, r.unit.Lib.Pkg, oldr.unit.Lib.Pkg)
}
l.objSyms[oldi] = objSym{r.objidx, li}
} else {
// old symbol overwrites new symbol.
typ := sym.AbiSymKindToSymKind[objabi.SymKind(oldsym.Type())]
if !typ.IsData() { // only allow overwriting data symbol
log.Fatalf("duplicated definition of symbol %s, from %s and %s", name, r.unit.Lib.Pkg, oldr.unit.Lib.Pkg)
} }
return oldi
}
// newExtSym creates a new external sym with the specified
// name/version.
func (l *Loader) newExtSym(name string, ver int) Sym {
i := Sym(len(l.objSyms))
if l.extStart == 0 {
l.extStart = i
}
l.growValues(int(i) + 1)
l.growAttrBitmaps(int(i) + 1)
pi := l.newPayload(name, ver)
l.objSyms = append(l.objSyms, objSym{l.extReader.objidx, uint32(pi)})
l.extReader.syms = append(l.extReader.syms, i)
return i
}
// LookupOrCreateSym looks up the symbol with the specified name/version,
// returning its Sym index if found. If the lookup fails, a new external
// Sym will be created, entered into the lookup tables, and returned.
func (l *Loader) LookupOrCreateSym(name string, ver int) Sym {
i := l.Lookup(name, ver)
if i != 0 {
return i
}
i = l.newExtSym(name, ver)
static := ver >= sym.SymVerStatic || ver < 0
if static {
l.extStaticSyms[nameVer{name, ver}] = i
} else {
l.symsByName[ver][name] = i
}
return i
}
// AddCgoExport records a cgo-exported symbol in l.CgoExports.
// This table is used to identify the correct Go symbol ABI to use
// to resolve references from host objects (which don't have ABIs).
func (l *Loader) AddCgoExport(s Sym) {
if l.CgoExports == nil {
l.CgoExports = make(map[string]Sym)
}
l.CgoExports[l.SymName(s)] = s
}
// LookupOrCreateCgoExport is like LookupOrCreateSym, but if ver
// indicates a global symbol, it uses the CgoExport table to determine
// the appropriate symbol version (ABI) to use. ver must be either 0
// or a static symbol version.
func (l *Loader) LookupOrCreateCgoExport(name string, ver int) Sym {
if ver >= sym.SymVerStatic {
return l.LookupOrCreateSym(name, ver)
}
if ver != 0 {
panic("ver must be 0 or a static version")
}
// Look for a cgo-exported symbol from Go.
if s, ok := l.CgoExports[name]; ok {
return s
}
// Otherwise, this must just be a symbol in the host object.
// Create a version 0 symbol for it.
return l.LookupOrCreateSym(name, 0)
}
func (l *Loader) IsExternal(i Sym) bool {
r, _ := l.toLocal(i)
return l.isExtReader(r)}
func (l *Loader) isExtReader(r *oReader) bool {
return r == l.extReader
}
// For external symbol, return its index in the payloads array.
// XXX result is actually not a global index. We (ab)use the Sym type
// so we don't need conversion for accessing bitmaps.
func (l *Loader) extIndex(i Sym) Sym {
_, li := l.toLocal(i)
return Sym(li)
}
// Get a new payload for external symbol, return its index in
// the payloads array.
func (l *Loader) newPayload(name string, ver int) int {
pi := len(l.payloads)
pp := l.allocPayload()
pp.name = name
pp.ver = ver
l.payloads = append(l.payloads, pp)
l.growExtAttrBitmaps()
return pi
}
// getPayload returns a pointer to the extSymPayload struct for an
// external symbol if the symbol has a payload. Will panic if the
// symbol in question is bogus (zero or not an external sym).
func (l *Loader) getPayload(i Sym) *extSymPayload {
if !l.IsExternal(i) {
panic(fmt.Sprintf("bogus symbol index %d in getPayload", i))
}
pi := l.extIndex(i)
return l.payloads[pi]
}
// allocPayload allocates a new payload.
func (l *Loader) allocPayload() *extSymPayload {
batch := l.payloadBatch
if len(batch) == 0 {
batch = make([]extSymPayload, 1000)
}
p := &batch[0]
l.payloadBatch = batch[1:]
return p
}
func (ms *extSymPayload) Grow(siz int64) {
if int64(int(siz)) != siz {
log.Fatalf("symgrow size %d too long", siz)
}
if int64(len(ms.data)) >= siz {
return
}
if cap(ms.data) < int(siz) {
cl := len(ms.data)
ms.data = append(ms.data, make([]byte, int(siz)+1-cl)...)
ms.data = ms.data[0:cl]
}
ms.data = ms.data[:siz]
}
// Convert a local index to a global index.
func (l *Loader) toGlobal(r *oReader, i uint32) Sym {
return r.syms[i]
}
// Convert a global index to a local index.
func (l *Loader) toLocal(i Sym) (*oReader, uint32) { return l.objs[l.objSyms[i].objidx].r, l.objSyms[i].s
}
// Resolve a local symbol reference. Return global index.
func (l *Loader) resolve(r *oReader, s goobj.SymRef) Sym {
var rr *oReader
switch p := s.PkgIdx; p {
case goobj.PkgIdxInvalid:
// {0, X} with non-zero X is never a valid sym reference from a Go object.
// We steal this space for symbol references from external objects.
// In this case, X is just the global index.
if l.isExtReader(r) {
return Sym(s.SymIdx)
}
if s.SymIdx != 0 {
panic("bad sym ref")
}
return 0
case goobj.PkgIdxHashed64:
i := int(s.SymIdx) + r.ndef
return r.syms[i]
case goobj.PkgIdxHashed:
i := int(s.SymIdx) + r.ndef + r.nhashed64def
return r.syms[i]
case goobj.PkgIdxNone:
i := int(s.SymIdx) + r.ndef + r.nhashed64def + r.nhasheddef
return r.syms[i]
case goobj.PkgIdxBuiltin:
if bi := l.builtinSyms[s.SymIdx]; bi != 0 {
return bi
}
l.reportMissingBuiltin(int(s.SymIdx), r.unit.Lib.Pkg)
return 0
case goobj.PkgIdxSelf:
rr = r
default:
rr = l.objs[r.pkg[p]].r
}
return l.toGlobal(rr, s.SymIdx)
}
// reportMissingBuiltin issues an error in the case where we have a
// relocation against a runtime builtin whose definition is not found
// when the runtime package is built. The canonical example is
// "runtime.racefuncenter" -- currently if you do something like
//
// go build -gcflags=-race myprogram.go
//
// the compiler will insert calls to the builtin runtime.racefuncenter,
// but the version of the runtime used for linkage won't actually contain
// definitions of that symbol. See issue #42396 for details.
//
// As currently implemented, this is a fatal error. This has drawbacks
// in that if there are multiple missing builtins, the error will only
// cite the first one. On the plus side, terminating the link here has
// advantages in that we won't run the risk of panics or crashes later
// on in the linker due to R_CALL relocations with 0-valued target
// symbols.
func (l *Loader) reportMissingBuiltin(bsym int, reflib string) {
bname, _ := goobj.BuiltinName(bsym)
log.Fatalf("reference to undefined builtin %q from package %q",
bname, reflib)
}
// Look up a symbol by name, return global index, or 0 if not found.
// This is more like Syms.ROLookup than Lookup -- it doesn't create
// new symbol.
func (l *Loader) Lookup(name string, ver int) Sym {
if ver >= sym.SymVerStatic || ver < 0 {
return l.extStaticSyms[nameVer{name, ver}] }
return l.symsByName[ver][name]
}
// Check that duplicate symbols have same contents.
func (l *Loader) checkdup(name string, r *oReader, li uint32, dup Sym) {
p := r.Data(li)
rdup, ldup := l.toLocal(dup)
pdup := rdup.Data(ldup)
reason := "same length but different contents"
if len(p) != len(pdup) {
reason = fmt.Sprintf("new length %d != old length %d", len(p), len(pdup))
} else if bytes.Equal(p, pdup) {
// For BSS symbols, we need to check size as well, see issue 46653.
szdup := l.SymSize(dup)
sz := int64(r.Sym(li).Siz())
if szdup == sz {
return
}
reason = fmt.Sprintf("different sizes: new size %d != old size %d",
sz, szdup)
}
fmt.Fprintf(os.Stderr, "cmd/link: while reading object for '%v': duplicate symbol '%s', previous def at '%v', with mismatched payload: %s\n", r.unit.Lib, name, rdup.unit.Lib, reason)
// For the moment, allow DWARF subprogram DIEs for
// auto-generated wrapper functions. What seems to happen
// here is that we get different line numbers on formal
// params; I am guessing that the pos is being inherited
// from the spot where the wrapper is needed.
allowed := strings.HasPrefix(name, "go.info.go.interface") ||
strings.HasPrefix(name, "go.info.go.builtin") ||
strings.HasPrefix(name, "go.debuglines")
if !allowed {
l.strictDupMsgs++
}
}
func (l *Loader) NStrictDupMsgs() int { return l.strictDupMsgs }
// Number of total symbols.
func (l *Loader) NSym() int {
return len(l.objSyms)
}
// Number of defined Go symbols.
func (l *Loader) NDef() int {
return int(l.extStart)
}
// Number of reachable symbols.
func (l *Loader) NReachableSym() int {
return l.attrReachable.Count()
}
// Returns the raw (unpatched) name of the i-th symbol.
func (l *Loader) RawSymName(i Sym) string {
if l.IsExternal(i) {
pp := l.getPayload(i)
return pp.name
}
r, li := l.toLocal(i)
return r.Sym(li).Name(r.Reader)
}
// Returns the (patched) name of the i-th symbol.
func (l *Loader) SymName(i Sym) string {
if l.IsExternal(i) {
pp := l.getPayload(i)
return pp.name
} r, li := l.toLocal(i)
if r == nil {
return "?"
}
name := r.Sym(li).Name(r.Reader)
if !r.NeedNameExpansion() {
return name
}
return strings.Replace(name, "\"\".", r.pkgprefix, -1)
}
// Returns the version of the i-th symbol.
func (l *Loader) SymVersion(i Sym) int {
if l.IsExternal(i) {
pp := l.getPayload(i)
return pp.ver
}
r, li := l.toLocal(i)
return int(abiToVer(r.Sym(li).ABI(), r.version))
}
func (l *Loader) IsFileLocal(i Sym) bool {
return l.SymVersion(i) >= sym.SymVerStatic
}
// IsFromAssembly returns true if this symbol is derived from an
// object file generated by the Go assembler.
func (l *Loader) IsFromAssembly(i Sym) bool {
if l.IsExternal(i) {
return false
}
r, _ := l.toLocal(i)
return r.FromAssembly()
}
// Returns the type of the i-th symbol.
func (l *Loader) SymType(i Sym) sym.SymKind {
if l.IsExternal(i) {
pp := l.getPayload(i)
if pp != nil {
return pp.kind
}
return 0
}
r, li := l.toLocal(i)
return sym.AbiSymKindToSymKind[objabi.SymKind(r.Sym(li).Type())]
}
// Returns the attributes of the i-th symbol.
func (l *Loader) SymAttr(i Sym) uint8 {
if l.IsExternal(i) {
// TODO: do something? External symbols have different representation of attributes.
// For now, ReflectMethod, NoSplit, GoType, and Typelink are used and they cannot be
// set by external symbol.
return 0
}
r, li := l.toLocal(i)
return r.Sym(li).Flag()
}
// Returns the size of the i-th symbol.
func (l *Loader) SymSize(i Sym) int64 {
if l.IsExternal(i) {
pp := l.getPayload(i)
return pp.size
}
r, li := l.toLocal(i)
return int64(r.Sym(li).Siz())
}
// AttrReachable returns true for symbols that are transitively
// referenced from the entry points. Unreachable symbols are not
// written to the output.
func (l *Loader) AttrReachable(i Sym) bool {
return l.attrReachable.Has(i)
}
// SetAttrReachable sets the reachability property for a symbol (see
// AttrReachable).
func (l *Loader) SetAttrReachable(i Sym, v bool) {
if v {
l.attrReachable.Set(i)
} else {
l.attrReachable.Unset(i)
}
}
// AttrOnList returns true for 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.
func (l *Loader) AttrOnList(i Sym) bool {
return l.attrOnList.Has(i)
}
// SetAttrOnList sets the "on list" property for a symbol (see
// AttrOnList).
func (l *Loader) SetAttrOnList(i Sym, v bool) {
if v {
l.attrOnList.Set(i)
} else {
l.attrOnList.Unset(i)
}
}
// AttrLocal returns true for symbols that are only visible within the
// module (executable or shared library) being linked. This attribute
// is applied to thunks and certain other linker-generated symbols.
func (l *Loader) AttrLocal(i Sym) bool {
return l.attrLocal.Has(i)
}
// SetAttrLocal the "local" property for a symbol (see AttrLocal above).
func (l *Loader) SetAttrLocal(i Sym, v bool) {
if v {
l.attrLocal.Set(i)
} else {
l.attrLocal.Unset(i)
}
}
// AttrUsedInIface returns true for a type symbol that is used in
// an interface.
func (l *Loader) AttrUsedInIface(i Sym) bool {
return l.attrUsedInIface.Has(i)
}
func (l *Loader) SetAttrUsedInIface(i Sym, v bool) {
if v {
l.attrUsedInIface.Set(i)
} else {
l.attrUsedInIface.Unset(i)
}
}
// SymAddr checks that a symbol is reachable, and returns its value.
func (l *Loader) SymAddr(i Sym) int64 {
if !l.AttrReachable(i) {
panic("unreachable symbol in symaddr")
} return l.values[i]
}
// AttrNotInSymbolTable returns true for symbols that should not be
// added to the symbol table of the final generated load module.
func (l *Loader) AttrNotInSymbolTable(i Sym) bool {
return l.attrNotInSymbolTable.Has(i)
}
// SetAttrNotInSymbolTable the "not in symtab" property for a symbol
// (see AttrNotInSymbolTable above).
func (l *Loader) SetAttrNotInSymbolTable(i Sym, v bool) {
if v {
l.attrNotInSymbolTable.Set(i)
} else {
l.attrNotInSymbolTable.Unset(i)
}
}
// AttrVisibilityHidden symbols returns true for 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.
func (l *Loader) AttrVisibilityHidden(i Sym) bool {
if !l.IsExternal(i) {
return false
}
return l.attrVisibilityHidden.Has(l.extIndex(i))
}
// SetAttrVisibilityHidden sets the "hidden visibility" property for a
// symbol (see AttrVisibilityHidden).
func (l *Loader) SetAttrVisibilityHidden(i Sym, v bool) {
if !l.IsExternal(i) {
panic("tried to set visibility attr on non-external symbol")
}
if v {
l.attrVisibilityHidden.Set(l.extIndex(i))
} else {
l.attrVisibilityHidden.Unset(l.extIndex(i))
}
}
// AttrDuplicateOK returns true for a symbol that can be present in
// multiple object files.
func (l *Loader) AttrDuplicateOK(i Sym) bool {
if !l.IsExternal(i) {
// TODO: if this path winds up being taken frequently, it
// might make more sense to copy the flag value out of the object
// into a larger bitmap during preload.
r, li := l.toLocal(i)
return r.Sym(li).Dupok()
}
return l.attrDuplicateOK.Has(l.extIndex(i))
}
// SetAttrDuplicateOK sets the "duplicate OK" property for an external
// symbol (see AttrDuplicateOK).
func (l *Loader) SetAttrDuplicateOK(i Sym, v bool) {
if !l.IsExternal(i) {
panic("tried to set dupok attr on non-external symbol")
}
if v {
l.attrDuplicateOK.Set(l.extIndex(i))
} else {
l.attrDuplicateOK.Unset(l.extIndex(i))
}
}
// AttrShared returns true for symbols compiled with the -shared option.func (l *Loader) AttrShared(i Sym) bool {
if !l.IsExternal(i) {
// TODO: if this path winds up being taken frequently, it
// might make more sense to copy the flag value out of the
// object into a larger bitmap during preload.
r, _ := l.toLocal(i)
return r.Shared()
}
return l.attrShared.Has(l.extIndex(i))
}
// SetAttrShared sets the "shared" property for an external
// symbol (see AttrShared).
func (l *Loader) SetAttrShared(i Sym, v bool) {
if !l.IsExternal(i) {
panic(fmt.Sprintf("tried to set shared attr on non-external symbol %d %s", i, l.SymName(i)))
}
if v {
l.attrShared.Set(l.extIndex(i))
} else {
l.attrShared.Unset(l.extIndex(i))
}
}
// AttrExternal returns true for function symbols loaded from host
// object files.
func (l *Loader) AttrExternal(i Sym) bool {
if !l.IsExternal(i) {
return false
}
return l.attrExternal.Has(l.extIndex(i))
}
// SetAttrExternal sets the "external" property for an host object
// symbol (see AttrExternal).
func (l *Loader) SetAttrExternal(i Sym, v bool) {
if !l.IsExternal(i) {
panic(fmt.Sprintf("tried to set external attr on non-external symbol %q", l.RawSymName(i)))
}
if v {
l.attrExternal.Set(l.extIndex(i))
} else {
l.attrExternal.Unset(l.extIndex(i))
}
}
// AttrSpecial returns true for a symbols that do not have their
// address (i.e. Value) computed by the usual mechanism of
// data.go:dodata() & data.go:address().
func (l *Loader) AttrSpecial(i Sym) bool {
_, ok := l.attrSpecial[i]
return ok
}
// SetAttrSpecial sets the "special" property for a symbol (see
// AttrSpecial).
func (l *Loader) SetAttrSpecial(i Sym, v bool) {
if v {
l.attrSpecial[i] = struct{}{}
} else {
delete(l.attrSpecial, i)
}
}
// AttrCgoExportDynamic returns true for a symbol that has been
// specially marked via the "cgo_export_dynamic" compiler directive
// written by cgo (in response to //export directives in the source).
func (l *Loader) AttrCgoExportDynamic(i Sym) bool {
_, ok := l.attrCgoExportDynamic[i]
return ok}
// SetAttrCgoExportDynamic sets the "cgo_export_dynamic" for a symbol
// (see AttrCgoExportDynamic).
func (l *Loader) SetAttrCgoExportDynamic(i Sym, v bool) {
if v {
l.attrCgoExportDynamic[i] = struct{}{}
} else {
delete(l.attrCgoExportDynamic, i)
}
}
// AttrCgoExportStatic returns true for a symbol that has been
// specially marked via the "cgo_export_static" directive
// written by cgo.
func (l *Loader) AttrCgoExportStatic(i Sym) bool {
_, ok := l.attrCgoExportStatic[i]
return ok
}
// SetAttrCgoExportStatic sets the "cgo_export_static" for a symbol
// (see AttrCgoExportStatic).
func (l *Loader) SetAttrCgoExportStatic(i Sym, v bool) {
if v {
l.attrCgoExportStatic[i] = struct{}{}
} else {
delete(l.attrCgoExportStatic, i)
}
}
// IsGeneratedSym returns true if a symbol's been previously marked as a
// generator symbol through the SetIsGeneratedSym. The functions for generator
// symbols are kept in the Link context.
func (l *Loader) IsGeneratedSym(i Sym) bool {
_, ok := l.generatedSyms[i]
return ok
}
// SetIsGeneratedSym marks symbols as generated symbols. Data shouldn't be
// stored in generated symbols, and a function is registered and called for
// each of these symbols.
func (l *Loader) SetIsGeneratedSym(i Sym, v bool) {
if !l.IsExternal(i) {
panic("only external symbols can be generated")
}
if v {
l.generatedSyms[i] = struct{}{}
} else {
delete(l.generatedSyms, i)
}
}
func (l *Loader) AttrCgoExport(i Sym) bool {
return l.AttrCgoExportDynamic(i) || l.AttrCgoExportStatic(i)
}
// AttrReadOnly returns true for a symbol whose underlying data
// is stored via a read-only mmap.
func (l *Loader) AttrReadOnly(i Sym) bool {
if v, ok := l.attrReadOnly[i]; ok {
return v
}
if l.IsExternal(i) {
pp := l.getPayload(i)
if pp.objidx != 0 {
return l.objs[pp.objidx].r.ReadOnly()
}
return false
}
r, _ := l.toLocal(i) return r.ReadOnly()
}
// SetAttrReadOnly sets the "data is read only" property for a symbol
// (see AttrReadOnly).
func (l *Loader) SetAttrReadOnly(i Sym, v bool) {
l.attrReadOnly[i] = v
}
// AttrSubSymbol returns true for symbols that are listed as a
// sub-symbol of some other outer symbol. The sub/outer mechanism is
// 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.
//
// Note that in later stages of the linker, we set Outer(S) to some
// container symbol C, but don't set Sub(C). Thus we have two
// distinct scenarios:
//
// - Outer symbol covers the address ranges of its sub-symbols.
// Outer.Sub is set in this case.
// - Outer symbol doesn't conver the address ranges. It is zero-sized
// and doesn't have sub-symbols. In the case, the inner symbol is
// not actually a "SubSymbol". (Tricky!)
//
// This method returns TRUE only for sub-symbols in the first scenario.
//
// FIXME: would be better to do away with this and have a better way
// to represent container symbols.
func (l *Loader) AttrSubSymbol(i Sym) bool {
// we don't explicitly store this attribute any more -- return
// a value based on the sub-symbol setting.
o := l.OuterSym(i)
if o == 0 {
return false
}
return l.SubSym(o) != 0
}
// Note that we don't have a 'SetAttrSubSymbol' method in the loader;
// clients should instead use the AddInteriorSym method to establish
// containment relationships for host object symbols.
// Returns whether the i-th symbol has ReflectMethod attribute set.
func (l *Loader) IsReflectMethod(i Sym) bool {
return l.SymAttr(i)&goobj.SymFlagReflectMethod != 0
}
// Returns whether the i-th symbol is nosplit.
func (l *Loader) IsNoSplit(i Sym) bool {
return l.SymAttr(i)&goobj.SymFlagNoSplit != 0
}
// Returns whether this is a Go type symbol.
func (l *Loader) IsGoType(i Sym) bool {
return l.SymAttr(i)&goobj.SymFlagGoType != 0
}
// Returns whether this symbol should be included in typelink.
func (l *Loader) IsTypelink(i Sym) bool {
return l.SymAttr(i)&goobj.SymFlagTypelink != 0
}
// Returns whether this symbol is an itab symbol.
func (l *Loader) IsItab(i Sym) bool {
if l.IsExternal(i) {
return false
} r, li := l.toLocal(i)
return r.Sym(li).IsItab()
}
// Returns whether this symbol is a dictionary symbol.
func (l *Loader) IsDict(i Sym) bool {
if l.IsExternal(i) {
return false
}
r, li := l.toLocal(i)
return r.Sym(li).IsDict()
}
// Return whether this is a trampoline of a deferreturn call.
func (l *Loader) IsDeferReturnTramp(i Sym) bool {
return l.deferReturnTramp[i]
}
// Set that i is a trampoline of a deferreturn call.
func (l *Loader) SetIsDeferReturnTramp(i Sym, v bool) {
l.deferReturnTramp[i] = v
}
// growValues grows the slice used to store symbol values.
func (l *Loader) growValues(reqLen int) {
curLen := len(l.values)
if reqLen > curLen {
l.values = append(l.values, make([]int64, reqLen+1-curLen)...)
}
}
// SymValue returns the value of the i-th symbol. i is global index.
func (l *Loader) SymValue(i Sym) int64 {
return l.values[i]
}
// SetSymValue sets the value of the i-th symbol. i is global index.
func (l *Loader) SetSymValue(i Sym, val int64) {
l.values[i] = val
}
// AddToSymValue adds to the value of the i-th symbol. i is the global index.
func (l *Loader) AddToSymValue(i Sym, val int64) {
l.values[i] += val
}
// Returns the symbol content of the i-th symbol. i is global index.
func (l *Loader) Data(i Sym) []byte {
if l.IsExternal(i) {
pp := l.getPayload(i)
if pp != nil {
return pp.data
}
return nil
}
r, li := l.toLocal(i)
return r.Data(li)
}
// FreeData clears the symbol data of an external symbol, allowing the memory
// to be freed earlier. No-op for non-external symbols.
// i is global index.
func (l *Loader) FreeData(i Sym) {
if l.IsExternal(i) {
pp := l.getPayload(i)
if pp != nil {
pp.data = nil
}
}
}
// SymAlign returns the alignment for a symbol.
func (l *Loader) SymAlign(i Sym) int32 {
if int(i) >= len(l.align) {
// align is extended lazily -- it the sym in question is
// outside the range of the existing slice, then we assume its
// alignment has not yet been set.
return 0
}
// TODO: would it make sense to return an arch-specific
// alignment depending on section type? E.g. STEXT => 32,
// SDATA => 1, etc?
abits := l.align[i]
if abits == 0 {
return 0
}
return int32(1 << (abits - 1))
}
// SetSymAlign sets the alignment for a symbol.
func (l *Loader) SetSymAlign(i Sym, align int32) {
// Reject nonsense alignments.
if align < 0 || align&(align-1) != 0 {
panic("bad alignment value")
}
if int(i) >= len(l.align) {
l.align = append(l.align, make([]uint8, l.NSym()-len(l.align))...)
}
if align == 0 {
l.align[i] = 0
}
l.align[i] = uint8(bits.Len32(uint32(align)))
}
// SymValue returns the section of the i-th symbol. i is global index.
func (l *Loader) SymSect(i Sym) *sym.Section {
if int(i) >= len(l.symSects) {
// symSects is extended lazily -- it the sym in question is
// outside the range of the existing slice, then we assume its
// section has not yet been set.
return nil
}
return l.sects[l.symSects[i]]
}
// SetSymSect sets the section of the i-th symbol. i is global index.
func (l *Loader) SetSymSect(i Sym, sect *sym.Section) {
if int(i) >= len(l.symSects) {
l.symSects = append(l.symSects, make([]uint16, l.NSym()-len(l.symSects))...)
}
l.symSects[i] = sect.Index
}
// growSects grows the slice used to store symbol sections.
func (l *Loader) growSects(reqLen int) {
curLen := len(l.symSects)
if reqLen > curLen {
l.symSects = append(l.symSects, make([]uint16, reqLen+1-curLen)...)
}
}
// NewSection creates a new (output) section.
func (l *Loader) NewSection() *sym.Section {
sect := new(sym.Section)
idx := len(l.sects)
if idx != int(uint16(idx)) {
panic("too many sections created")
}
sect.Index = uint16(idx)
l.sects = append(l.sects, sect) return sect
}
// SymDynImplib returns the "dynimplib" attribute for the specified
// symbol, making up a portion of the info for a symbol specified
// on a "cgo_import_dynamic" compiler directive.
func (l *Loader) SymDynimplib(i Sym) string {
return l.dynimplib[i]
}
// SetSymDynimplib sets the "dynimplib" attribute for a symbol.
func (l *Loader) SetSymDynimplib(i Sym, value string) {
// reject bad symbols
if i >= Sym(len(l.objSyms)) || i == 0 {
panic("bad symbol index in SetDynimplib")
}
if value == "" {
delete(l.dynimplib, i)
} else {
l.dynimplib[i] = value
}
}
// SymDynimpvers returns the "dynimpvers" attribute for the specified
// symbol, making up a portion of the info for a symbol specified
// on a "cgo_import_dynamic" compiler directive.
func (l *Loader) SymDynimpvers(i Sym) string {
return l.dynimpvers[i]
}
// SetSymDynimpvers sets the "dynimpvers" attribute for a symbol.
func (l *Loader) SetSymDynimpvers(i Sym, value string) {
// reject bad symbols
if i >= Sym(len(l.objSyms)) || i == 0 {
panic("bad symbol index in SetDynimpvers")
}
if value == "" {
delete(l.dynimpvers, i)
} else {
l.dynimpvers[i] = value
}
}
// SymExtname returns the "extname" value for the specified
// symbol.
func (l *Loader) SymExtname(i Sym) string {
if s, ok := l.extname[i]; ok {
return s
}
return l.SymName(i)
}
// SetSymExtname sets the "extname" attribute for a symbol.
func (l *Loader) SetSymExtname(i Sym, value string) {
// reject bad symbols
if i >= Sym(len(l.objSyms)) || i == 0 {
panic("bad symbol index in SetExtname")
}
if value == "" {
delete(l.extname, i)
} else {
l.extname[i] = value
}
}
// SymElfType returns the previously recorded ELF type for a symbol
// (used only 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).
func (l *Loader) SymElfType(i Sym) elf.SymType { if et, ok := l.elfType[i]; ok {
return et
}
return elf.STT_NOTYPE
}
// SetSymElfType sets the elf type attribute for a symbol.
func (l *Loader) SetSymElfType(i Sym, et elf.SymType) {
// reject bad symbols
if i >= Sym(len(l.objSyms)) || i == 0 {
panic("bad symbol index in SetSymElfType")
}
if et == elf.STT_NOTYPE {
delete(l.elfType, i)
} else {
l.elfType[i] = et
}
}
// SymElfSym returns the ELF symbol index for a given loader
// symbol, assigned during ELF symtab generation.
func (l *Loader) SymElfSym(i Sym) int32 {
return l.elfSym[i]
}
// SetSymElfSym sets the elf symbol index for a symbol.
func (l *Loader) SetSymElfSym(i Sym, es int32) {
if i == 0 {
panic("bad sym index")
}
if es == 0 {
delete(l.elfSym, i)
} else {
l.elfSym[i] = es
}
}
// SymLocalElfSym returns the "local" ELF symbol index for a given loader
// symbol, assigned during ELF symtab generation.
func (l *Loader) SymLocalElfSym(i Sym) int32 {
return l.localElfSym[i]
}
// SetSymLocalElfSym sets the "local" elf symbol index for a symbol.
func (l *Loader) SetSymLocalElfSym(i Sym, es int32) {
if i == 0 {
panic("bad sym index")
}
if es == 0 {
delete(l.localElfSym, i)
} else {
l.localElfSym[i] = es
}
}
// SymPlt returns the PLT offset of symbol s.
func (l *Loader) SymPlt(s Sym) int32 {
if v, ok := l.plt[s]; ok {
return v
}
return -1
}
// SetPlt sets the PLT offset of symbol i.
func (l *Loader) SetPlt(i Sym, v int32) {
if i >= Sym(len(l.objSyms)) || i == 0 {
panic("bad symbol for SetPlt")
}
if v == -1 {
delete(l.plt, i) } else {
l.plt[i] = v
}
}
// SymGot returns the GOT offset of symbol s.
func (l *Loader) SymGot(s Sym) int32 {
if v, ok := l.got[s]; ok {
return v
}
return -1
}
// SetGot sets the GOT offset of symbol i.
func (l *Loader) SetGot(i Sym, v int32) {
if i >= Sym(len(l.objSyms)) || i == 0 {
panic("bad symbol for SetGot")
}
if v == -1 {
delete(l.got, i)
} else {
l.got[i] = v
}
}
// SymDynid returns the "dynid" property for the specified symbol.
func (l *Loader) SymDynid(i Sym) int32 {
if s, ok := l.dynid[i]; ok {
return s
}
return -1
}
// SetSymDynid sets the "dynid" property for a symbol.
func (l *Loader) SetSymDynid(i Sym, val int32) {
// reject bad symbols
if i >= Sym(len(l.objSyms)) || i == 0 {
panic("bad symbol index in SetSymDynid")
}
if val == -1 {
delete(l.dynid, i)
} else {
l.dynid[i] = val
}
}
// DynIdSyms returns the set of symbols for which dynID is set to an
// interesting (non-default) value. This is expected to be a fairly
// small set.
func (l *Loader) DynidSyms() []Sym {
sl := make([]Sym, 0, len(l.dynid))
for s := range l.dynid {
sl = append(sl, s)
}
sort.Slice(sl, func(i, j int) bool { return sl[i] < sl[j] })
return sl
}
// SymGoType returns the 'Gotype' property for a given symbol (set by
// the Go compiler for variable symbols). This version relies on
// reading aux symbols for the target sym -- it could be that a faster
// approach would be to check for gotype during preload and copy the
// results in to a map (might want to try this at some point and see
// if it helps speed things up).
func (l *Loader) SymGoType(i Sym) Sym { return l.aux1(i, goobj.AuxGotype) }
// SymUnit returns the compilation unit for a given symbol (which will
// typically be nil for external or linker-manufactured symbols).
func (l *Loader) SymUnit(i Sym) *sym.CompilationUnit {
if l.IsExternal(i) { pp := l.getPayload(i)
if pp.objidx != 0 {
r := l.objs[pp.objidx].r
return r.unit
}
return nil
}
r, _ := l.toLocal(i)
return r.unit
}
// SymPkg returns the package where the symbol came from (for
// regular compiler-generated Go symbols), but in the case of
// building with "-linkshared" (when a symbol is read from a
// shared library), will hold the library name.
// NOTE: this corresponds to sym.Symbol.File field.
func (l *Loader) SymPkg(i Sym) string {
if f, ok := l.symPkg[i]; ok {
return f
}
if l.IsExternal(i) {
pp := l.getPayload(i)
if pp.objidx != 0 {
r := l.objs[pp.objidx].r
return r.unit.Lib.Pkg
}
return ""
}
r, _ := l.toLocal(i)
return r.unit.Lib.Pkg
}
// SetSymPkg sets the package/library for a symbol. This is
// needed mainly for external symbols, specifically those imported
// from shared libraries.
func (l *Loader) SetSymPkg(i Sym, pkg string) {
// reject bad symbols
if i >= Sym(len(l.objSyms)) || i == 0 {
panic("bad symbol index in SetSymPkg")
}
l.symPkg[i] = pkg
}
// SymLocalentry returns the "local entry" value for the specified
// symbol.
func (l *Loader) SymLocalentry(i Sym) uint8 {
return l.localentry[i]
}
// SetSymLocalentry sets the "local entry" attribute for a symbol.
func (l *Loader) SetSymLocalentry(i Sym, value uint8) {
// reject bad symbols
if i >= Sym(len(l.objSyms)) || i == 0 {
panic("bad symbol index in SetSymLocalentry")
}
if value == 0 {
delete(l.localentry, i)
} else {
l.localentry[i] = value
}
}
// Returns the number of aux symbols given a global index.
func (l *Loader) NAux(i Sym) int {
if l.IsExternal(i) {
return 0
}
r, li := l.toLocal(i)
return r.NAux(li)
}
// Returns the "handle" to the j-th aux symbol of the i-th symbol.
func (l *Loader) Aux(i Sym, j int) Aux {
if l.IsExternal(i) {
return Aux{}
}
r, li := l.toLocal(i)
if j >= r.NAux(li) {
return Aux{}
}
return Aux{r.Aux(li, j), r, l}
}
// GetFuncDwarfAuxSyms collects and returns the auxiliary DWARF
// symbols associated with a given function symbol. Prior to the
// introduction of the loader, this was done purely using name
// lookups, e.f. for function with name XYZ we would then look up
// go.info.XYZ, etc.
func (l *Loader) GetFuncDwarfAuxSyms(fnSymIdx Sym) (auxDwarfInfo, auxDwarfLoc, auxDwarfRanges, auxDwarfLines Sym) {
if l.SymType(fnSymIdx) != sym.STEXT {
log.Fatalf("error: non-function sym %d/%s t=%s passed to GetFuncDwarfAuxSyms", fnSymIdx, l.SymName(fnSymIdx), l.SymType(fnSymIdx).String())
}
if l.IsExternal(fnSymIdx) {
// Current expectation is that any external function will
// not have auxsyms.
return
}
r, li := l.toLocal(fnSymIdx)
auxs := r.Auxs(li)
for i := range auxs {
a := &auxs[i]
switch a.Type() {
case goobj.AuxDwarfInfo:
auxDwarfInfo = l.resolve(r, a.Sym())
if l.SymType(auxDwarfInfo) != sym.SDWARFFCN {
panic("aux dwarf info sym with wrong type")
}
case goobj.AuxDwarfLoc:
auxDwarfLoc = l.resolve(r, a.Sym())
if l.SymType(auxDwarfLoc) != sym.SDWARFLOC {
panic("aux dwarf loc sym with wrong type")
}
case goobj.AuxDwarfRanges:
auxDwarfRanges = l.resolve(r, a.Sym())
if l.SymType(auxDwarfRanges) != sym.SDWARFRANGE {
panic("aux dwarf ranges sym with wrong type")
}
case goobj.AuxDwarfLines:
auxDwarfLines = l.resolve(r, a.Sym())
if l.SymType(auxDwarfLines) != sym.SDWARFLINES {
panic("aux dwarf lines sym with wrong type")
}
}
}
return
}
// AddInteriorSym sets up 'interior' as an interior symbol of
// container/payload symbol 'container'. An interior symbol does not
// itself have data, but gives a name to a subrange of the data in its
// container symbol. The container itself may or may not have a name.
// This method is intended primarily for use in the host object
// loaders, to capture the semantics of symbols and sections in an
// object file. When reading a host object file, we'll typically
// encounter a static section symbol (ex: ".text") containing content
// for a collection of functions, then a series of ELF (or macho, etc)
// symbol table entries each of which points into a sub-section
// (offset and length) of its corresponding container symbol. Within
// the go linker we create a loader.Sym for the container (which is
// expected to have the actual content/payload) and then a set of// interior loader.Sym's that point into a portion of the container.
func (l *Loader) AddInteriorSym(container Sym, interior Sym) {
// Container symbols are expected to have content/data.
// NB: this restriction may turn out to be too strict (it's possible
// to imagine a zero-sized container with an interior symbol pointing
// into it); it's ok to relax or remove it if we counter an
// oddball host object that triggers this.
if l.SymSize(container) == 0 && len(l.Data(container)) == 0 {
panic("unexpected empty container symbol")
}
// The interior symbols for a container are not expected to have
// content/data or relocations.
if len(l.Data(interior)) != 0 {
panic("unexpected non-empty interior symbol")
}
// Interior symbol is expected to be in the symbol table.
if l.AttrNotInSymbolTable(interior) {
panic("interior symbol must be in symtab")
}
// Only a single level of containment is allowed.
if l.OuterSym(container) != 0 {
panic("outer has outer itself")
}
// Interior sym should not already have a sibling.
if l.SubSym(interior) != 0 {
panic("sub set for subsym")
}
// Interior sym should not already point at a container.
if l.OuterSym(interior) != 0 {
panic("outer already set for subsym")
}
l.sub[interior] = l.sub[container]
l.sub[container] = interior
l.outer[interior] = container
}
// OuterSym gets the outer symbol for host object loaded symbols.
func (l *Loader) OuterSym(i Sym) Sym {
// FIXME: add check for isExternal?
return l.outer[i]
}
// SubSym gets the subsymbol for host object loaded symbols.
func (l *Loader) SubSym(i Sym) Sym {
// NB: note -- no check for l.isExternal(), since I am pretty sure
// that later phases in the linker set subsym for "type." syms
return l.sub[i]
}
// SetCarrierSym declares that 'c' is the carrier or container symbol
// for 's'. Carrier symbols are used in the linker to as a container
// for a collection of sub-symbols where the content of the
// sub-symbols is effectively concatenated to form the content of the
// carrier. The carrier is given a name in the output symbol table
// while the sub-symbol names are not. For example, the Go compiler
// emits named string symbols (type SGOSTRING) when compiling a
// package; after being deduplicated, these symbols are collected into
// a single unit by assigning them a new carrier symbol named
// "go.string.*" (which appears in the final symbol table for the
// output load module).
func (l *Loader) SetCarrierSym(s Sym, c Sym) {
if c == 0 {
panic("invalid carrier in SetCarrierSym")
}
if s == 0 {
panic("invalid sub-symbol in SetCarrierSym")
}
// Carrier symbols are not expected to have content/data. It is
// ok for them to have non-zero size (to allow for use of generator
// symbols). if len(l.Data(c)) != 0 {
panic("unexpected non-empty carrier symbol")
}
l.outer[s] = c
// relocsym's foldSubSymbolOffset requires that we only
// have a single level of containment-- enforce here.
if l.outer[c] != 0 {
panic("invalid nested carrier sym")
}
}
// Initialize Reachable bitmap and its siblings for running deadcode pass.
func (l *Loader) InitReachable() {
l.growAttrBitmaps(l.NSym() + 1)
}
type symWithVal struct {
s Sym
v int64
}
type bySymValue []symWithVal
func (s bySymValue) Len() int { return len(s) }
func (s bySymValue) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func (s bySymValue) Less(i, j int) bool { return s[i].v < s[j].v }
// SortSub walks through the sub-symbols for 's' and sorts them
// in place by increasing value. Return value is the new
// sub symbol for the specified outer symbol.
func (l *Loader) SortSub(s Sym) Sym {
if s == 0 || l.sub[s] == 0 {
return s
}
// Sort symbols using a slice first. Use a stable sort on the off
// chance that there's more than once symbol with the same value,
// so as to preserve reproducible builds.
sl := []symWithVal{}
for ss := l.sub[s]; ss != 0; ss = l.sub[ss] {
sl = append(sl, symWithVal{s: ss, v: l.SymValue(ss)})
}
sort.Stable(bySymValue(sl))
// Then apply any changes needed to the sub map.
ns := Sym(0)
for i := len(sl) - 1; i >= 0; i-- {
s := sl[i].s
l.sub[s] = ns
ns = s
}
// Update sub for outer symbol, then return
l.sub[s] = sl[0].s
return sl[0].s
}
// SortSyms sorts a list of symbols by their value.
func (l *Loader) SortSyms(ss []Sym) {
sort.SliceStable(ss, func(i, j int) bool { return l.SymValue(ss[i]) < l.SymValue(ss[j]) })
}
// Insure that reachable bitmap and its siblings have enough size.
func (l *Loader) growAttrBitmaps(reqLen int) {
if reqLen > l.attrReachable.Len() {
// These are indexed by global symbol
l.attrReachable = growBitmap(reqLen, l.attrReachable)
l.attrOnList = growBitmap(reqLen, l.attrOnList)
l.attrLocal = growBitmap(reqLen, l.attrLocal)
l.attrNotInSymbolTable = growBitmap(reqLen, l.attrNotInSymbolTable) l.attrUsedInIface = growBitmap(reqLen, l.attrUsedInIface)
}
l.growExtAttrBitmaps()
}
func (l *Loader) growExtAttrBitmaps() {
// These are indexed by external symbol index (e.g. l.extIndex(i))
extReqLen := len(l.payloads)
if extReqLen > l.attrVisibilityHidden.Len() {
l.attrVisibilityHidden = growBitmap(extReqLen, l.attrVisibilityHidden)
l.attrDuplicateOK = growBitmap(extReqLen, l.attrDuplicateOK)
l.attrShared = growBitmap(extReqLen, l.attrShared)
l.attrExternal = growBitmap(extReqLen, l.attrExternal)
}
}
func (relocs *Relocs) Count() int { return len(relocs.rs) }
// At returns the j-th reloc for a global symbol.
func (relocs *Relocs) At(j int) Reloc {
if relocs.l.isExtReader(relocs.r) {
return Reloc{&relocs.rs[j], relocs.r, relocs.l}
}
return Reloc{&relocs.rs[j], relocs.r, relocs.l}
}
// Relocs returns a Relocs object for the given global sym.
func (l *Loader) Relocs(i Sym) Relocs {
r, li := l.toLocal(i)
if r == nil {
panic(fmt.Sprintf("trying to get oreader for invalid sym %d\n\n", i))
}
return l.relocs(r, li)
}
// Relocs returns a Relocs object given a local sym index and reader.
func (l *Loader) relocs(r *oReader, li uint32) Relocs {
var rs []goobj.Reloc
if l.isExtReader(r) {
pp := l.payloads[li]
rs = pp.relocs
} else {
rs = r.Relocs(li)
}
return Relocs{
rs: rs,
li: li,
r: r,
l: l,
}
}
func (l *Loader) auxs(i Sym) (*oReader, []goobj.Aux) {
if l.IsExternal(i) {
pp := l.getPayload(i)
return l.objs[pp.objidx].r, pp.auxs
} else {
r, li := l.toLocal(i)
return r, r.Auxs(li)
}
}
// Returns a specific aux symbol of type t for symbol i.
func (l *Loader) aux1(i Sym, t uint8) Sym {
r, auxs := l.auxs(i)
for j := range auxs {
a := &auxs[j]
if a.Type() == t {
return l.resolve(r, a.Sym())
} }
return 0
}
func (l *Loader) Pcsp(i Sym) Sym { return l.aux1(i, goobj.AuxPcsp) }
// Returns all aux symbols of per-PC data for symbol i.
// tmp is a scratch space for the pcdata slice.
func (l *Loader) PcdataAuxs(i Sym, tmp []Sym) (pcsp, pcfile, pcline, pcinline Sym, pcdata []Sym) {
pcdata = tmp[:0]
r, auxs := l.auxs(i)
for j := range auxs {
a := &auxs[j]
switch a.Type() {
case goobj.AuxPcsp:
pcsp = l.resolve(r, a.Sym())
case goobj.AuxPcline:
pcline = l.resolve(r, a.Sym())
case goobj.AuxPcfile:
pcfile = l.resolve(r, a.Sym())
case goobj.AuxPcinline:
pcinline = l.resolve(r, a.Sym())
case goobj.AuxPcdata:
pcdata = append(pcdata, l.resolve(r, a.Sym()))
}
}
return
}
// Returns the number of pcdata for symbol i.
func (l *Loader) NumPcdata(i Sym) int {
n := 0
_, auxs := l.auxs(i)
for j := range auxs {
a := &auxs[j]
if a.Type() == goobj.AuxPcdata {
n++
}
}
return n
}
// Returns all funcdata symbols of symbol i.
// tmp is a scratch space.
func (l *Loader) Funcdata(i Sym, tmp []Sym) []Sym {
fd := tmp[:0]
r, auxs := l.auxs(i)
for j := range auxs {
a := &auxs[j]
if a.Type() == goobj.AuxFuncdata {
fd = append(fd, l.resolve(r, a.Sym()))
}
}
return fd
}
// Returns the number of funcdata for symbol i.
func (l *Loader) NumFuncdata(i Sym) int {
n := 0
_, auxs := l.auxs(i)
for j := range auxs {
a := &auxs[j]
if a.Type() == goobj.AuxFuncdata {
n++
}
}
return n
}
// FuncInfo provides hooks to access goobj.FuncInfo in the objects.type FuncInfo struct {
l *Loader
r *oReader
data []byte
lengths goobj.FuncInfoLengths
}
func (fi *FuncInfo) Valid() bool { return fi.r != nil }
func (fi *FuncInfo) Args() int {
return int((*goobj.FuncInfo)(nil).ReadArgs(fi.data))
}
func (fi *FuncInfo) Locals() int {
return int((*goobj.FuncInfo)(nil).ReadLocals(fi.data))
}
func (fi *FuncInfo) FuncID() objabi.FuncID {
return (*goobj.FuncInfo)(nil).ReadFuncID(fi.data)
}
func (fi *FuncInfo) FuncFlag() objabi.FuncFlag {
return (*goobj.FuncInfo)(nil).ReadFuncFlag(fi.data)
}
// Preload has to be called prior to invoking the various methods
// below related to pcdata, funcdataoff, files, and inltree nodes.
func (fi *FuncInfo) Preload() {
fi.lengths = (*goobj.FuncInfo)(nil).ReadFuncInfoLengths(fi.data)
}
func (fi *FuncInfo) NumFile() uint32 {
if !fi.lengths.Initialized {
panic("need to call Preload first")
}
return fi.lengths.NumFile
}
func (fi *FuncInfo) File(k int) goobj.CUFileIndex {
if !fi.lengths.Initialized {
panic("need to call Preload first")
}
return (*goobj.FuncInfo)(nil).ReadFile(fi.data, fi.lengths.FileOff, uint32(k))
}
// TopFrame returns true if the function associated with this FuncInfo
// is an entry point, meaning that unwinders should stop when they hit
// this function.
func (fi *FuncInfo) TopFrame() bool {
return (fi.FuncFlag() & objabi.FuncFlag_TOPFRAME) != 0
}
type InlTreeNode struct {
Parent int32
File goobj.CUFileIndex
Line int32
Func Sym
ParentPC int32
}
func (fi *FuncInfo) NumInlTree() uint32 {
if !fi.lengths.Initialized {
panic("need to call Preload first")
}
return fi.lengths.NumInlTree
}
func (fi *FuncInfo) InlTree(k int) InlTreeNode {
if !fi.lengths.Initialized {
panic("need to call Preload first") }
node := (*goobj.FuncInfo)(nil).ReadInlTree(fi.data, fi.lengths.InlTreeOff, uint32(k))
return InlTreeNode{
Parent: node.Parent,
File: node.File,
Line: node.Line,
Func: fi.l.resolve(fi.r, node.Func),
ParentPC: node.ParentPC,
}
}
func (l *Loader) FuncInfo(i Sym) FuncInfo {
r, auxs := l.auxs(i)
for j := range auxs {
a := &auxs[j]
if a.Type() == goobj.AuxFuncInfo {
b := r.Data(a.Sym().SymIdx)
return FuncInfo{l, r, b, goobj.FuncInfoLengths{}}
}
}
return FuncInfo{}
}
// Preload a package: adds autolib.
// Does not add defined package or non-packaged symbols to the symbol table.
// These are done in LoadSyms.
// Does not read symbol data.
// Returns the fingerprint of the object.
func (l *Loader) Preload(localSymVersion int, f *bio.Reader, lib *sym.Library, unit *sym.CompilationUnit, length int64) goobj.FingerprintType {
roObject, readonly, err := f.Slice(uint64(length)) // TODO: no need to map blocks that are for tools only (e.g. RefName)
if err != nil {
log.Fatal("cannot read object file:", err)
}
r := goobj.NewReaderFromBytes(roObject, readonly)
if r == nil {
if len(roObject) >= 8 && bytes.Equal(roObject[:8], []byte("\x00go114ld")) {
log.Fatalf("found object file %s in old format", f.File().Name())
}
panic("cannot read object file")
}
pkgprefix := objabi.PathToPrefix(lib.Pkg) + "."
ndef := r.NSym()
nhashed64def := r.NHashed64def()
nhasheddef := r.NHasheddef()
or := &oReader{
Reader: r,
unit: unit,
version: localSymVersion,
flags: r.Flags(),
pkgprefix: pkgprefix,
syms: make([]Sym, ndef+nhashed64def+nhasheddef+r.NNonpkgdef()+r.NNonpkgref()),
ndef: ndef,
nhasheddef: nhasheddef,
nhashed64def: nhashed64def,
objidx: uint32(len(l.objs)),
}
// Autolib
lib.Autolib = append(lib.Autolib, r.Autolib()...)
// DWARF file table
nfile := r.NFile()
unit.FileTable = make([]string, nfile)
for i := range unit.FileTable {
unit.FileTable[i] = r.File(i)
}
l.addObj(lib.Pkg, or)
// The caller expects us consuming all the data f.MustSeek(length, os.SEEK_CUR)
return r.Fingerprint()
}
// Holds the loader along with temporary states for loading symbols.
type loadState struct {
l *Loader
hashed64Syms map[uint64]symAndSize // short hashed (content-addressable) symbols, keyed by content hash
hashedSyms map[goobj.HashType]symAndSize // hashed (content-addressable) symbols, keyed by content hash
}
// Preload symbols of given kind from an object.
func (st *loadState) preloadSyms(r *oReader, kind int) {
l := st.l
var start, end uint32
switch kind {
case pkgDef:
start = 0
end = uint32(r.ndef)
case hashed64Def:
start = uint32(r.ndef)
end = uint32(r.ndef + r.nhashed64def)
case hashedDef:
start = uint32(r.ndef + r.nhashed64def)
end = uint32(r.ndef + r.nhashed64def + r.nhasheddef)
if l.hasUnknownPkgPath {
// The content hash depends on symbol name expansion. If any package is
// built without fully expanded names, the content hash is unreliable.
// Treat them as named symbols.
// This is rare.
// (We don't need to do this for hashed64Def case, as there the hash
// function is simply the identity function, which doesn't depend on
// name expansion.)
kind = nonPkgDef
}
case nonPkgDef:
start = uint32(r.ndef + r.nhashed64def + r.nhasheddef)
end = uint32(r.ndef + r.nhashed64def + r.nhasheddef + r.NNonpkgdef())
default:
panic("preloadSyms: bad kind")
}
l.growAttrBitmaps(len(l.objSyms) + int(end-start))
needNameExpansion := r.NeedNameExpansion()
loadingRuntimePkg := r.unit.Lib.Pkg == "runtime"
for i := start; i < end; i++ {
osym := r.Sym(i)
var name string
var v int
if kind != hashed64Def && kind != hashedDef { // we don't need the name, etc. for hashed symbols
name = osym.Name(r.Reader)
if needNameExpansion {
name = strings.Replace(name, "\"\".", r.pkgprefix, -1)
}
v = abiToVer(osym.ABI(), r.version)
}
gi := st.addSym(name, v, r, i, kind, osym)
r.syms[i] = gi
if osym.Local() {
l.SetAttrLocal(gi, true)
}
if osym.UsedInIface() {
l.SetAttrUsedInIface(gi, true)
}
if strings.HasPrefix(name, "runtime.") ||
(loadingRuntimePkg && strings.HasPrefix(name, "type.")) {
if bi := goobj.BuiltinIdx(name, int(osym.ABI())); bi != -1 {
// This is a definition of a builtin symbol. Record where it is.
l.builtinSyms[bi] = gi
} }
if a := int32(osym.Align()); a != 0 && a > l.SymAlign(gi) {
l.SetSymAlign(gi, a)
}
}
}
// Add syms, hashed (content-addressable) symbols, non-package symbols, and
// references to external symbols (which are always named).
func (l *Loader) LoadSyms(arch *sys.Arch) {
// Allocate space for symbols, making a guess as to how much space we need.
// This function was determined empirically by looking at the cmd/compile on
// Darwin, and picking factors for hashed and hashed64 syms.
var symSize, hashedSize, hashed64Size int
for _, o := range l.objs[goObjStart:] {
symSize += o.r.ndef + o.r.nhasheddef/2 + o.r.nhashed64def/2 + o.r.NNonpkgdef()
hashedSize += o.r.nhasheddef / 2
hashed64Size += o.r.nhashed64def / 2
}
// Index 0 is invalid for symbols.
l.objSyms = make([]objSym, 1, symSize)
st := loadState{
l: l,
hashed64Syms: make(map[uint64]symAndSize, hashed64Size),
hashedSyms: make(map[goobj.HashType]symAndSize, hashedSize),
}
for _, o := range l.objs[goObjStart:] {
st.preloadSyms(o.r, pkgDef)
}
l.npkgsyms = l.NSym()
for _, o := range l.objs[goObjStart:] {
st.preloadSyms(o.r, hashed64Def)
st.preloadSyms(o.r, hashedDef)
st.preloadSyms(o.r, nonPkgDef)
}
l.nhashedsyms = len(st.hashed64Syms) + len(st.hashedSyms)
for _, o := range l.objs[goObjStart:] {
loadObjRefs(l, o.r, arch)
}
l.values = make([]int64, l.NSym(), l.NSym()+1000) // +1000 make some room for external symbols
}
func loadObjRefs(l *Loader, r *oReader, arch *sys.Arch) {
// load non-package refs
ndef := uint32(r.NAlldef())
needNameExpansion := r.NeedNameExpansion()
for i, n := uint32(0), uint32(r.NNonpkgref()); i < n; i++ {
osym := r.Sym(ndef + i)
name := osym.Name(r.Reader)
if needNameExpansion {
name = strings.Replace(name, "\"\".", r.pkgprefix, -1)
}
v := abiToVer(osym.ABI(), r.version)
r.syms[ndef+i] = l.LookupOrCreateSym(name, v)
gi := r.syms[ndef+i]
if osym.Local() {
l.SetAttrLocal(gi, true)
}
if osym.UsedInIface() {
l.SetAttrUsedInIface(gi, true)
}
}
// referenced packages
npkg := r.NPkg()
r.pkg = make([]uint32, npkg)
for i := 1; i < npkg; i++ { // PkgIdx 0 is a dummy invalid package
pkg := r.Pkg(i) objidx, ok := l.objByPkg[pkg]
if !ok {
log.Fatalf("%v: reference to nonexistent package %s", r.unit.Lib, pkg)
}
r.pkg[i] = objidx
}
// load flags of package refs
for i, n := 0, r.NRefFlags(); i < n; i++ {
rf := r.RefFlags(i)
gi := l.resolve(r, rf.Sym())
if rf.Flag2()&goobj.SymFlagUsedInIface != 0 {
l.SetAttrUsedInIface(gi, true)
}
}
}
func abiToVer(abi uint16, localSymVersion int) int {
var v int
if abi == goobj.SymABIstatic {
// Static
v = localSymVersion
} else if abiver := sym.ABIToVersion(obj.ABI(abi)); abiver != -1 {
// Note that data symbols are "ABI0", which maps to version 0.
v = abiver
} else {
log.Fatalf("invalid symbol ABI: %d", abi)
}
return v
}
// TopLevelSym tests a symbol (by name and kind) to determine whether
// the symbol first class sym (participating in the link) or is an
// anonymous aux or sub-symbol containing some sub-part or payload of
// another symbol.
func (l *Loader) TopLevelSym(s Sym) bool {
return topLevelSym(l.RawSymName(s), l.SymType(s))
}
// topLevelSym tests a symbol name and kind to determine whether
// the symbol first class sym (participating in the link) or is an
// anonymous aux or sub-symbol containing some sub-part or payload of
// another symbol.
func topLevelSym(sname string, skind sym.SymKind) bool {
if sname != "" {
return true
}
switch skind {
case sym.SDWARFFCN, sym.SDWARFABSFCN, sym.SDWARFTYPE, sym.SDWARFCONST, sym.SDWARFCUINFO, sym.SDWARFRANGE, sym.SDWARFLOC, sym.SDWARFLINES, sym.SGOFUNC:
return true
default:
return false
}
}
// cloneToExternal takes the existing object file symbol (symIdx)
// and creates a new external symbol payload that is a clone with
// respect to name, version, type, relocations, etc. The idea here
// is that if the linker decides it wants to update the contents of
// a symbol originally discovered as part of an object file, it's
// easier to do this if we make the updates to an external symbol
// payload.
func (l *Loader) cloneToExternal(symIdx Sym) {
if l.IsExternal(symIdx) {
panic("sym is already external, no need for clone")
}
// Read the particulars from object.
r, li := l.toLocal(symIdx)
osym := r.Sym(li) sname := osym.Name(r.Reader)
if r.NeedNameExpansion() {
sname = strings.Replace(sname, "\"\".", r.pkgprefix, -1)
}
sver := abiToVer(osym.ABI(), r.version)
skind := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())]
// Create new symbol, update version and kind.
pi := l.newPayload(sname, sver)
pp := l.payloads[pi]
pp.kind = skind
pp.ver = sver
pp.size = int64(osym.Siz())
pp.objidx = r.objidx
// If this is a def, then copy the guts. We expect this case
// to be very rare (one case it may come up is with -X).
if li < uint32(r.NAlldef()) {
// Copy relocations
relocs := l.Relocs(symIdx)
pp.relocs = make([]goobj.Reloc, relocs.Count())
for i := range pp.relocs {
// Copy the relocs slice.
// Convert local reference to global reference.
rel := relocs.At(i)
pp.relocs[i].Set(rel.Off(), rel.Siz(), uint16(rel.Type()), rel.Add(), goobj.SymRef{PkgIdx: 0, SymIdx: uint32(rel.Sym())})
}
// Copy data
pp.data = r.Data(li)
}
// If we're overriding a data symbol, collect the associated
// Gotype, so as to propagate it to the new symbol.
auxs := r.Auxs(li)
pp.auxs = auxs
// Install new payload to global index space.
// (This needs to happen at the end, as the accessors above
// need to access the old symbol content.)
l.objSyms[symIdx] = objSym{l.extReader.objidx, uint32(pi)}
l.extReader.syms = append(l.extReader.syms, symIdx)
}
// Copy the payload of symbol src to dst. Both src and dst must be external
// symbols.
// The intended use case is that when building/linking against a shared library,
// where we do symbol name mangling, the Go object file may have reference to
// the original symbol name whereas the shared library provides a symbol with
// the mangled name. When we do mangling, we copy payload of mangled to original.
func (l *Loader) CopySym(src, dst Sym) {
if !l.IsExternal(dst) {
panic("dst is not external") //l.newExtSym(l.SymName(dst), l.SymVersion(dst))
}
if !l.IsExternal(src) {
panic("src is not external") //l.cloneToExternal(src)
}
l.payloads[l.extIndex(dst)] = l.payloads[l.extIndex(src)]
l.SetSymPkg(dst, l.SymPkg(src))
// TODO: other attributes?
}
// CopyAttributes copies over all of the attributes of symbol 'src' to
// symbol 'dst'.
func (l *Loader) CopyAttributes(src Sym, dst Sym) {
l.SetAttrReachable(dst, l.AttrReachable(src))
l.SetAttrOnList(dst, l.AttrOnList(src))
l.SetAttrLocal(dst, l.AttrLocal(src))
l.SetAttrNotInSymbolTable(dst, l.AttrNotInSymbolTable(src)) if l.IsExternal(dst) {
l.SetAttrVisibilityHidden(dst, l.AttrVisibilityHidden(src))
l.SetAttrDuplicateOK(dst, l.AttrDuplicateOK(src))
l.SetAttrShared(dst, l.AttrShared(src))
l.SetAttrExternal(dst, l.AttrExternal(src))
} else {
// Some attributes are modifiable only for external symbols.
// In such cases, don't try to transfer over the attribute
// from the source even if there is a clash. This comes up
// when copying attributes from a dupOK ABI wrapper symbol to
// the real target symbol (which may not be marked dupOK).
}
l.SetAttrSpecial(dst, l.AttrSpecial(src))
l.SetAttrCgoExportDynamic(dst, l.AttrCgoExportDynamic(src))
l.SetAttrCgoExportStatic(dst, l.AttrCgoExportStatic(src))
l.SetAttrReadOnly(dst, l.AttrReadOnly(src))
}
// CreateExtSym creates a new external symbol with the specified name
// without adding it to any lookup tables, returning a Sym index for it.
func (l *Loader) CreateExtSym(name string, ver int) Sym {
return l.newExtSym(name, ver)
}
// CreateStaticSym creates a new static symbol with the specified name
// without adding it to any lookup tables, returning a Sym index for it.
func (l *Loader) CreateStaticSym(name string) Sym {
// Assign a new unique negative version -- this is to mark the
// symbol so that it is not included in the name lookup table.
l.anonVersion--
return l.newExtSym(name, l.anonVersion)
}
func (l *Loader) FreeSym(i Sym) {
if l.IsExternal(i) {
pp := l.getPayload(i)
*pp = extSymPayload{}
}
}
// relocId is essentially a <S,R> tuple identifying the Rth
// relocation of symbol S.
type relocId struct {
sym Sym
ridx int
}
// SetRelocVariant sets the 'variant' property of a relocation on
// some specific symbol.
func (l *Loader) SetRelocVariant(s Sym, ri int, v sym.RelocVariant) {
// sanity check
if relocs := l.Relocs(s); ri >= relocs.Count() {
panic("invalid relocation ID")
}
if l.relocVariant == nil {
l.relocVariant = make(map[relocId]sym.RelocVariant)
}
if v != 0 {
l.relocVariant[relocId{s, ri}] = v
} else {
delete(l.relocVariant, relocId{s, ri})
}
}
// RelocVariant returns the 'variant' property of a relocation on
// some specific symbol.
func (l *Loader) RelocVariant(s Sym, ri int) sym.RelocVariant {
return l.relocVariant[relocId{s, ri}]
}
// UndefinedRelocTargets iterates through the global symbol index
// space, looking for symbols with relocations targeting undefined
// references. The linker's loadlib method uses this to determine if
// there are unresolved references to functions in system libraries
// (for example, libgcc.a), presumably due to CGO code. Return
// value is a list of loader.Sym's corresponding to the undefined
// cross-refs. The "limit" param controls the maximum number of
// results returned; if "limit" is -1, then all undefs are returned.
func (l *Loader) UndefinedRelocTargets(limit int) []Sym {
result := []Sym{}
for si := Sym(1); si < Sym(len(l.objSyms)); si++ {
relocs := l.Relocs(si)
for ri := 0; ri < relocs.Count(); ri++ {
r := relocs.At(ri)
rs := r.Sym()
if rs != 0 && l.SymType(rs) == sym.SXREF && l.RawSymName(rs) != ".got" {
result = append(result, rs)
if limit != -1 && len(result) >= limit {
break
}
}
}
}
return result
}
// AssignTextSymbolOrder populates the Textp slices within each
// library and compilation unit, insuring that packages are laid down
// in dependency order (internal first, then everything else). Return value
// is a slice of all text syms.
func (l *Loader) AssignTextSymbolOrder(libs []*sym.Library, intlibs []bool, extsyms []Sym) []Sym {
// Library Textp lists should be empty at this point.
for _, lib := range libs {
if len(lib.Textp) != 0 {
panic("expected empty Textp slice for library")
}
if len(lib.DupTextSyms) != 0 {
panic("expected empty DupTextSyms slice for library")
}
}
// Used to record which dupok symbol we've assigned to a unit.
// Can't use the onlist attribute here because it will need to
// clear for the later assignment of the sym.Symbol to a unit.
// NB: we can convert to using onList once we no longer have to
// call the regular addToTextp.
assignedToUnit := MakeBitmap(l.NSym() + 1)
// Start off textp with reachable external syms.
textp := []Sym{}
for _, sym := range extsyms {
if !l.attrReachable.Has(sym) {
continue
}
textp = append(textp, sym)
}
// Walk through all text symbols from Go object files and append
// them to their corresponding library's textp list.
for _, o := range l.objs[goObjStart:] {
r := o.r
lib := r.unit.Lib
for i, n := uint32(0), uint32(r.NAlldef()); i < n; i++ {
gi := l.toGlobal(r, i)
if !l.attrReachable.Has(gi) {
continue
}
osym := r.Sym(i)
st := sym.AbiSymKindToSymKind[objabi.SymKind(osym.Type())] if st != sym.STEXT {
continue
}
dupok := osym.Dupok()
if r2, i2 := l.toLocal(gi); r2 != r || i2 != i {
// A dupok text symbol is resolved to another package.
// We still need to record its presence in the current
// package, as the trampoline pass expects packages
// are laid out in dependency order.
lib.DupTextSyms = append(lib.DupTextSyms, sym.LoaderSym(gi))
continue // symbol in different object
}
if dupok {
lib.DupTextSyms = append(lib.DupTextSyms, sym.LoaderSym(gi))
continue
}
lib.Textp = append(lib.Textp, sym.LoaderSym(gi))
}
}
// Now assemble global textp, and assign text symbols to units.
for _, doInternal := range [2]bool{true, false} {
for idx, lib := range libs {
if intlibs[idx] != doInternal {
continue
}
lists := [2][]sym.LoaderSym{lib.Textp, lib.DupTextSyms}
for i, list := range lists {
for _, s := range list {
sym := Sym(s)
if !assignedToUnit.Has(sym) {
textp = append(textp, sym)
unit := l.SymUnit(sym)
if unit != nil {
unit.Textp = append(unit.Textp, s)
assignedToUnit.Set(sym)
}
// Dupok symbols may be defined in multiple packages; the
// associated package for a dupok sym is chosen sort of
// arbitrarily (the first containing package that the linker
// loads). Canonicalizes its Pkg to the package with which
// it will be laid down in text.
if i == 1 /* DupTextSyms2 */ && l.SymPkg(sym) != lib.Pkg {
l.SetSymPkg(sym, lib.Pkg)
}
}
}
}
lib.Textp = nil
lib.DupTextSyms = nil
}
}
return textp
}
// ErrorReporter is a helper class for reporting errors.
type ErrorReporter struct {
ldr *Loader
AfterErrorAction func()
}
// Errorf method logs an error message.
//
// After each error, the error actions function will be invoked; this
// will either terminate the link immediately (if -h option given)
// or it will keep a count and exit if more than 20 errors have been printed.
//
// Logging an error means that on exit cmd/link will delete any// output file and return a non-zero error code.
//
func (reporter *ErrorReporter) Errorf(s Sym, format string, args ...interface{}) {
if s != 0 && reporter.ldr.SymName(s) != "" {
// Note: Replace is needed here because symbol names might have % in them,
// due to the use of LinkString for names of instantiating types.
format = strings.Replace(reporter.ldr.SymName(s), "%", "%%", -1) + ": " + format
} else {
format = fmt.Sprintf("sym %d: %s", s, format)
}
format += "\n"
fmt.Fprintf(os.Stderr, format, args...)
reporter.AfterErrorAction()
}
// GetErrorReporter returns the loader's associated error reporter.
func (l *Loader) GetErrorReporter() *ErrorReporter {
return l.errorReporter
}
// Errorf method logs an error message. See ErrorReporter.Errorf for details.
func (l *Loader) Errorf(s Sym, format string, args ...interface{}) {
l.errorReporter.Errorf(s, format, args...)
}
// Symbol statistics.
func (l *Loader) Stat() string {
s := fmt.Sprintf("%d symbols, %d reachable\n", l.NSym(), l.NReachableSym())
s += fmt.Sprintf("\t%d package symbols, %d hashed symbols, %d non-package symbols, %d external symbols\n",
l.npkgsyms, l.nhashedsyms, int(l.extStart)-l.npkgsyms-l.nhashedsyms, l.NSym()-int(l.extStart))
return s
}
// For debugging.
func (l *Loader) Dump() {
fmt.Println("objs")
for _, obj := range l.objs[goObjStart:] {
if obj.r != nil {
fmt.Println(obj.i, obj.r.unit.Lib)
}
}
fmt.Println("extStart:", l.extStart)
fmt.Println("Nsyms:", len(l.objSyms))
fmt.Println("syms")
for i := Sym(1); i < Sym(len(l.objSyms)); i++ {
pi := ""
if l.IsExternal(i) {
pi = fmt.Sprintf("<ext %d>", l.extIndex(i))
}
sect := ""
if l.SymSect(i) != nil {
sect = l.SymSect(i).Name
}
fmt.Printf("%v %v %v %v %x %v\n", i, l.SymName(i), l.SymType(i), pi, l.SymValue(i), sect)
}
fmt.Println("symsByName")
for name, i := range l.symsByName[0] {
fmt.Println(i, name, 0)
}
for name, i := range l.symsByName[1] {
fmt.Println(i, name, 1)
}
fmt.Println("payloads:")
for i := range l.payloads {
pp := l.payloads[i]
fmt.Println(i, pp.name, pp.ver, pp.kind)
}
}