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2720 lines (2445 loc) · 79.6 KB
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// 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/goobj2"
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/sys"
"cmd/link/internal/sym"
"debug/elf"
"fmt"
"log"
"math/bits"
"os"
"sort"
"strconv"
"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 []goobj2.Reloc2
li int // local index of symbol whose relocs we're examining
r *oReader // object reader for containing package
l *Loader // loader
}
// Reloc contains the payload for a specific relocation.
// TODO: replace this with sym.Reloc, once we change the
// relocation target from "*sym.Symbol" to "loader.Sym" in sym.Reloc.
type Reloc struct {
Off int32 // offset to rewrite
Size uint8 // number of bytes to rewrite: 0, 1, 2, or 4
Type objabi.RelocType // the relocation type
Add int64 // addend
Sym Sym // global index of symbol the reloc addresses
}
// Reloc2 holds a "handle" to access a relocation record from an
// object file.
type Reloc2 struct {
*goobj2.Reloc2
r *oReader
l *Loader
// External reloc types may not fit into a uint8 which the Go object file uses.
// Store it here, instead of in the byte of goobj2.Reloc2.
// For Go symbols this will always be 0.
// goobj2.Reloc2.Type() + typ is always the right type, for both Go and external
// symbols.
typ objabi.RelocType
}
func (rel Reloc2) Type() objabi.RelocType { return objabi.RelocType(rel.Reloc2.Type()) + rel.typ }
func (rel Reloc2) Sym() Sym { return rel.l.resolve(rel.r, rel.Reloc2.Sym()) }
func (rel Reloc2) SetSym(s Sym) { rel.Reloc2.SetSym(goobj2.SymRef{PkgIdx: 0, SymIdx: uint32(s)}) }
func (rel Reloc2) SetType(t objabi.RelocType) {
if t != objabi.RelocType(uint8(t)) {
panic("SetType: type doesn't fit into Reloc2")
}
rel.Reloc2.SetType(uint8(t))
}
// Aux2 holds a "handle" to access an aux symbol record from an
// object file.
type Aux2 struct {
*goobj2.Aux2
r *oReader
l *Loader
}
func (a Aux2) Sym() Sym { return a.l.resolve(a.r, a.Aux2.Sym()) }
// oReader is a wrapper type of obj.Reader, along with some
// extra information.
// TODO: rename to objReader once the old one is gone?
type oReader struct {
*goobj2.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
ndef int // cache goobj2.Reader.NSym()
objidx uint32 // index of this reader in the objs slice
}
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, r is l.extReader, s is its index into the
// payload array.
// {nil, 0} represents the nil symbol.
type objSym struct {
r *oReader
s int // 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
}
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
}
// 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.
//
// - For now, in loader.LoadFull we convert all symbols (Go + external)
// to sym.Symbols.
//
// - At some point (when the wayfront is pushed through all of the
// linker), all external symbols will be payload-based, and we can
// get rid of the loader.Syms array.
//
// - 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
itablink map[Sym]struct{} // itablink[j] defined if j is go.itablink.*
objByPkg map[string]*oReader // map package path to its Go object reader
Syms []*sym.Symbol // indexed symbols. XXX we still make sym.Symbol for now.
symBatch []sym.Symbol // batch of symbols.
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 glob 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
attrTopFrame map[Sym]struct{} // top frame symbols
attrSpecial map[Sym]struct{} // "special" frame symbols
attrCgoExportDynamic map[Sym]struct{} // "cgo_export_dynamic" symbols
attrCgoExportStatic map[Sym]struct{} // "cgo_export_static" symbols
// 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
align map[Sym]int32 // stores alignment for symbols
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
symFile map[Sym]string // stores file 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
// 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
relocBatch []sym.Reloc // for bulk allocation of relocations
flags uint32
strictDupMsgs int // number of strict-dup warning/errors, when FlagStrictDups is enabled
elfsetstring elfsetstringFunc
SymLookup func(name string, ver int) *sym.Symbol
}
const (
pkgDef = iota
nonPkgDef
nonPkgRef
)
type elfsetstringFunc func(s *sym.Symbol, 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
gotype Sym // Gotype (0 if not present)
relocs []goobj2.Reloc2
reltypes []objabi.RelocType // relocation types
data []byte
}
const (
// Loader.flags
FlagStrictDups = 1 << iota
)
func NewLoader(flags uint32, elfsetstring elfsetstringFunc) *Loader {
nbuiltin := goobj2.NBuiltin()
return &Loader{
start: make(map[*oReader]Sym),
objs: []objIdx{{}}, // reserve index 0 for nil symbol
objSyms: []objSym{{}}, // reserve index 0 for nil symbol
extReader: &oReader{},
symsByName: [2]map[string]Sym{make(map[string]Sym, 100000), make(map[string]Sym, 50000)}, // preallocate ~2MB for ABI0 and ~1MB for ABI1 symbols
objByPkg: make(map[string]*oReader),
outer: make(map[Sym]Sym),
sub: make(map[Sym]Sym),
align: make(map[Sym]int32),
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),
symFile: make(map[Sym]string),
plt: make(map[Sym]int32),
got: make(map[Sym]int32),
dynid: make(map[Sym]int32),
attrTopFrame: make(map[Sym]struct{}),
attrSpecial: make(map[Sym]struct{}),
attrCgoExportDynamic: make(map[Sym]struct{}),
attrCgoExportStatic: make(map[Sym]struct{}),
itablink: make(map[Sym]struct{}),
extStaticSyms: make(map[nameVer]Sym),
builtinSyms: make([]Sym, nbuiltin),
flags: flags,
elfsetstring: elfsetstring,
}
}
// 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
}
i := Sym(len(l.objSyms))
l.start[r] = i
l.objs = append(l.objs, objIdx{r, i})
return i
}
// Add a symbol from an object file, return the global index and whether it is added.
// If the symbol already exist, it returns the index of that symbol.
func (l *Loader) AddSym(name string, ver int, r *oReader, li int, kind int, dupok bool, typ sym.SymKind) (Sym, bool) {
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, li})
}
if name == "" {
addToGlobal()
return i, true // 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, true
}
if kind == 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, true
}
// 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, true
}
// symbol already exists
if dupok {
if l.flags&FlagStrictDups != 0 {
l.checkdup(name, r, li, oldi)
}
return oldi, false
}
oldr, oldli := l.toLocal(oldi)
oldsym := oldr.Sym2(oldli)
if oldsym.Dupok() {
return oldi, false
}
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 " + name)
}
l.objSyms[oldi] = objSym{r, li}
} else {
// old symbol overwrites new symbol.
if !typ.IsData() { // only allow overwriting data symbol
log.Fatalf("duplicated definition of symbol " + name)
}
}
return oldi, true
}
// 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.growSyms(int(i))
pi := l.newPayload(name, ver)
l.objSyms = append(l.objSyms, objSym{l.extReader, int(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
}
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]
}
// Ensure Syms slice has enough space.
func (l *Loader) growSyms(i int) {
n := len(l.Syms)
if n > i {
return
}
l.Syms = append(l.Syms, make([]*sym.Symbol, i+1-n)...)
l.growValues(int(i) + 1)
l.growAttrBitmaps(int(i) + 1)
}
// Convert a local index to a global index.
func (l *Loader) toGlobal(r *oReader, i int) Sym {
return r.syms[i]
}
// Convert a global index to a local index.
func (l *Loader) toLocal(i Sym) (*oReader, int) {
return l.objSyms[i].r, int(l.objSyms[i].s)
}
// Resolve a local symbol reference. Return global index.
func (l *Loader) resolve(r *oReader, s goobj2.SymRef) Sym {
var rr *oReader
switch p := s.PkgIdx; p {
case goobj2.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 goobj2.PkgIdxNone:
i := int(s.SymIdx) + r.ndef
return r.syms[i]
case goobj2.PkgIdxBuiltin:
return l.builtinSyms[s.SymIdx]
case goobj2.PkgIdxSelf:
rr = r
default:
pkg := r.Pkg(int(p))
var ok bool
rr, ok = l.objByPkg[pkg]
if !ok {
log.Fatalf("reference of nonexisted package %s, from %v", pkg, r.unit.Lib)
}
}
return l.toGlobal(rr, int(s.SymIdx))
}
// 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 int, dup Sym) {
p := r.Data(li)
rdup, ldup := l.toLocal(dup)
pdup := rdup.Data(ldup)
if bytes.Equal(p, pdup) {
return
}
reason := "same length but different contents"
if len(p) != len(pdup) {
reason = fmt.Sprintf("new length %d != old length %d", len(p), len(pdup))
}
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, whitelist 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.
whitelist := strings.HasPrefix(name, "go.info.go.interface") ||
strings.HasPrefix(name, "go.info.go.builtin") ||
strings.HasPrefix(name, "go.debuglines")
if !whitelist {
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)
}
// 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.Sym2(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)
return strings.Replace(r.Sym2(li).Name(r.Reader), "\"\".", 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.Sym2(li).ABI(), r.version))
}
// 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.Sym2(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 is the only thing matters and it cannot be set by external symbol.
return 0
}
r, li := l.toLocal(i)
return r.Sym2(li).Flag()
}
// 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)
}
}
// 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.Sym2(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.Flags() & goobj2.ObjFlagShared) != 0
}
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))
}
}
// AttrTopFrame returns true for a function symbol that is an entry
// point, meaning that unwinders should stop when they hit this
// function.
func (l *Loader) AttrTopFrame(i Sym) bool {
_, ok := l.attrTopFrame[i]
return ok
}
// SetAttrTopFrame sets the "top frame" property for a symbol (see
// AttrTopFrame).
func (l *Loader) SetAttrTopFrame(i Sym, v bool) {
if v {
l.attrTopFrame[i] = struct{}{}
} else {
delete(l.attrTopFrame, 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)
}
}
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.
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.
return l.OuterSym(i) != 0
}
// AttrContainer 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.
func (l *Loader) AttrContainer(i Sym) bool {
// we don't explicitly store this attribute any more -- return
// a value based on the sub-symbol setting.
return l.SubSym(i) != 0
}
// Note that we don't have SetAttrSubSymbol' or 'SetAttrContainer' methods
// in the loader; clients should just use methods like PrependSub
// to establish these relationships
// Returns whether the i-th symbol has ReflectMethod attribute set.
func (l *Loader) IsReflectMethod(i Sym) bool {
return l.SymAttr(i)&goobj2.SymFlagReflectMethod != 0
}
// Returns whether the i-th symbol is nosplit.
func (l *Loader) IsNoSplit(i Sym) bool {
return l.SymAttr(i)&goobj2.SymFlagNoSplit != 0
}
// Returns whether this is a Go type symbol.
func (l *Loader) IsGoType(i Sym) bool {
return l.SymAttr(i)&goobj2.SymFlagGoType != 0
}
// Returns whether this is a "go.itablink.*" symbol.
func (l *Loader) IsItabLink(i Sym) bool {
if _, ok := l.itablink[i]; ok {
return true
}
return false
}
// 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
}
// 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)