// Copyright 2013 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 ld
import (
"cmd/internal/objabi"
"cmd/internal/src"
"cmd/internal/sys"
"cmd/link/internal/sym"
"encoding/binary"
"log"
"os"
"path/filepath"
"strings"
)
// PCIter iterates over encoded pcdata tables.
type PCIter struct {
p []byte
pc uint32
nextpc uint32
pcscale uint32
value int32
start bool
done bool
}
// newPCIter creates a PCIter and configures it for ctxt's architecture.
func newPCIter(ctxt *Link) *PCIter {
it := new(PCIter)
it.pcscale = uint32(ctxt.Arch.MinLC)
return it
}
// next advances it to the next pc.
func (it *PCIter) next() {
it.pc = it.nextpc
if it.done {
return
}
if len(it.p) == 0 {
it.done = true
return
}
// value delta
val, n := binary.Varint(it.p)
if n <= 0 {
log.Fatalf("bad value varint in pciternext: read %v", n)
}
it.p = it.p[n:]
if val == 0 && !it.start {
it.done = true
return
}
it.start = false
it.value += int32(val)
// pc delta
pc, n := binary.Uvarint(it.p)
if n <= 0 {
log.Fatalf("bad pc varint in pciternext: read %v", n)
}
it.p = it.p[n:]
it.nextpc = it.pc + uint32(pc)*it.pcscale
}
// init prepares it to iterate over p,
// and advances it to the first pc.
func (it *PCIter) init(p []byte) {
it.p = p
it.pc = 0
it.nextpc = 0
it.value = -1
it.start = true
it.done = false
it.next()
}
func ftabaddstring(ftab *sym.Symbol, s string) int32 {
start := len(ftab.P)
ftab.Grow(int64(start + len(s) + 1)) // make room for s plus trailing NUL
copy(ftab.P[start:], s)
return int32(start)
}
// numberfile assigns a file number to the file if it hasn't been assigned already.
func numberfile(ctxt *Link, file *sym.Symbol) {
if file.Type != sym.SFILEPATH {
ctxt.Filesyms = append(ctxt.Filesyms, file)
file.Value = int64(len(ctxt.Filesyms))
file.Type = sym.SFILEPATH
path := file.Name[len(src.FileSymPrefix):]
file.Name = expandGoroot(path)
}
}
func renumberfiles(ctxt *Link, files []*sym.Symbol, d *sym.Pcdata) {
// Give files numbers.
for _, f := range files {
numberfile(ctxt, f)
}
buf := make([]byte, binary.MaxVarintLen32)
newval := int32(-1)
var out sym.Pcdata
it := newPCIter(ctxt)
for it.init(d.P); !it.done; it.next() {
// value delta
oldval := it.value
var val int32
if oldval == -1 {
val = -1
} else {
if oldval < 0 || oldval >= int32(len(files)) {
log.Fatalf("bad pcdata %d", oldval)
}
val = int32(files[oldval].Value)
}
dv := val - newval
newval = val
// value
n := binary.PutVarint(buf, int64(dv))
out.P = append(out.P, buf[:n]...)
// pc delta
pc := (it.nextpc - it.pc) / it.pcscale
n = binary.PutUvarint(buf, uint64(pc))
out.P = append(out.P, buf[:n]...)
}
// terminating value delta
// we want to write varint-encoded 0, which is just 0
out.P = append(out.P, 0)
*d = out
}
// onlycsymbol reports whether this is a symbol that is referenced by C code.
func onlycsymbol(s *sym.Symbol) bool {
switch s.Name {
case "_cgo_topofstack", "__cgo_topofstack", "_cgo_panic", "crosscall2":
return true
}
if strings.HasPrefix(s.Name, "_cgoexp_") {
return true
}
return false
}
func emitPcln(ctxt *Link, s *sym.Symbol) bool {
if s == nil {
return true
}
if ctxt.BuildMode == BuildModePlugin && ctxt.HeadType == objabi.Hdarwin && onlycsymbol(s) {
return false
}
// We want to generate func table entries only for the "lowest level" symbols,
// not containers of subsymbols.
return !s.Attr.Container()
}
// pclntab initializes the pclntab symbol with
// runtime function and file name information.
var pclntabZpcln sym.FuncInfo
// These variables are used to initialize runtime.firstmoduledata, see symtab.go:symtab.
var pclntabNfunc int32
var pclntabFiletabOffset int32
var pclntabPclntabOffset int32
var pclntabFirstFunc *sym.Symbol
var pclntabLastFunc *sym.Symbol
func (ctxt *Link) pclntab() {
funcdataBytes := int64(0)
ftab := ctxt.Syms.Lookup("runtime.pclntab", 0)
ftab.Type = sym.SPCLNTAB
ftab.Attr |= sym.AttrReachable
// See golang.org/s/go12symtab for the format. Briefly:
// 8-byte header
// nfunc [thearch.ptrsize bytes]
// function table, alternating PC and offset to func struct [each entry thearch.ptrsize bytes]
// end PC [thearch.ptrsize bytes]
// offset to file table [4 bytes]
// Find container symbols and mark them as such.
for _, s := range ctxt.Textp {
if s.Outer != nil {
s.Outer.Attr |= sym.AttrContainer
}
}
// Gather some basic stats and info.
var nfunc int32
for _, s := range ctxt.Textp {
if !emitPcln(ctxt, s) {
continue
}
nfunc++
if pclntabFirstFunc == nil {
pclntabFirstFunc = s
}
}
pclntabNfunc = nfunc
ftab.Grow(8 + int64(ctxt.Arch.PtrSize) + int64(nfunc)*2*int64(ctxt.Arch.PtrSize) + int64(ctxt.Arch.PtrSize) + 4)
ftab.SetUint32(ctxt.Arch, 0, 0xfffffffb)
ftab.SetUint8(ctxt.Arch, 6, uint8(ctxt.Arch.MinLC))
ftab.SetUint8(ctxt.Arch, 7, uint8(ctxt.Arch.PtrSize))
ftab.SetUint(ctxt.Arch, 8, uint64(nfunc))
pclntabPclntabOffset = int32(8 + ctxt.Arch.PtrSize)
funcnameoff := make(map[string]int32)
nameToOffset := func(name string) int32 {
nameoff, ok := funcnameoff[name]
if !ok {
nameoff = ftabaddstring(ftab, name)
funcnameoff[name] = nameoff
}
return nameoff
}
pctaboff := make(map[string]uint32)
writepctab := func(off int32, p []byte) int32 {
start, ok := pctaboff[string(p)]
if !ok {
if len(p) > 0 {
start = uint32(len(ftab.P))
ftab.AddBytes(p)
}
pctaboff[string(p)] = start
}
newoff := int32(ftab.SetUint32(ctxt.Arch, int64(off), start))
return newoff
}
nfunc = 0 // repurpose nfunc as a running index
for _, s := range ctxt.Textp {
if !emitPcln(ctxt, s) {
continue
}
pcln := s.FuncInfo
if pcln == nil {
pcln = &pclntabZpcln
}
if len(pcln.InlTree) > 0 {
if len(pcln.Pcdata) <= objabi.PCDATA_InlTreeIndex {
// Create inlining pcdata table.
pcdata := make([]sym.Pcdata, objabi.PCDATA_InlTreeIndex+1)
copy(pcdata, pcln.Pcdata)
pcln.Pcdata = pcdata
}
if len(pcln.Funcdataoff) <= objabi.FUNCDATA_InlTree {
// Create inline tree funcdata.
funcdata := make([]*sym.Symbol, objabi.FUNCDATA_InlTree+1)
funcdataoff := make([]int64, objabi.FUNCDATA_InlTree+1)
copy(funcdata, pcln.Funcdata)
copy(funcdataoff, pcln.Funcdataoff)
pcln.Funcdata = funcdata
pcln.Funcdataoff = funcdataoff
}
}
funcstart := int32(len(ftab.P))
funcstart += int32(-len(ftab.P)) & (int32(ctxt.Arch.PtrSize) - 1) // align to ptrsize
ftab.SetAddr(ctxt.Arch, 8+int64(ctxt.Arch.PtrSize)+int64(nfunc)*2*int64(ctxt.Arch.PtrSize), s)
ftab.SetUint(ctxt.Arch, 8+int64(ctxt.Arch.PtrSize)+int64(nfunc)*2*int64(ctxt.Arch.PtrSize)+int64(ctxt.Arch.PtrSize), uint64(funcstart))
// Write runtime._func. Keep in sync with ../../../../runtime/runtime2.go:/_func
// and package debug/gosym.
// fixed size of struct, checked below
off := funcstart
end := funcstart + int32(ctxt.Arch.PtrSize) + 3*4 + 5*4 + int32(len(pcln.Pcdata))*4 + int32(len(pcln.Funcdata))*int32(ctxt.Arch.PtrSize)
if len(pcln.Funcdata) > 0 && (end&int32(ctxt.Arch.PtrSize-1) != 0) {
end += 4
}
ftab.Grow(int64(end))
// entry uintptr
off = int32(ftab.SetAddr(ctxt.Arch, int64(off), s))
// name int32
nameoff := nameToOffset(s.Name)
off = int32(ftab.SetUint32(ctxt.Arch, int64(off), uint32(nameoff)))
// args int32
// TODO: Move into funcinfo.
args := uint32(0)
if s.FuncInfo != nil {
args = uint32(s.FuncInfo.Args)
}
off = int32(ftab.SetUint32(ctxt.Arch, int64(off), args))
// deferreturn
deferreturn := uint32(0)
lastWasmAddr := uint32(0)
for _, r := range s.R {
if ctxt.Arch.Family == sys.Wasm && r.Type == objabi.R_ADDR {
// Wasm does not have a live variable set at the deferreturn
// call itself. Instead it has one identified by the
// resumption point immediately preceding the deferreturn.
// The wasm code has a R_ADDR relocation which is used to
// set the resumption point to PC_B.
lastWasmAddr = uint32(r.Add)
}
if r.Type.IsDirectJump() && r.Sym != nil && r.Sym.Name == "runtime.deferreturn" {
if ctxt.Arch.Family == sys.Wasm {
deferreturn = lastWasmAddr
} else {
// Note: the relocation target is in the call instruction, but
// is not necessarily the whole instruction (for instance, on
// x86 the relocation applies to bytes [1:5] of the 5 byte call
// instruction).
deferreturn = uint32(r.Off)
}
break // only need one
}
}
off = int32(ftab.SetUint32(ctxt.Arch, int64(off), deferreturn))
if pcln != &pclntabZpcln {
renumberfiles(ctxt, pcln.File, &pcln.Pcfile)
if false {
// Sanity check the new numbering
it := newPCIter(ctxt)
for it.init(pcln.Pcfile.P); !it.done; it.next() {
if it.value < 1 || it.value > int32(len(ctxt.Filesyms)) {
Errorf(s, "bad file number in pcfile: %d not in range [1, %d]\n", it.value, len(ctxt.Filesyms))
errorexit()
}
}
}
}
if len(pcln.InlTree) > 0 {
inlTreeSym := ctxt.Syms.Lookup("inltree."+s.Name, 0)
inlTreeSym.Type = sym.SRODATA
inlTreeSym.Attr |= sym.AttrReachable | sym.AttrDuplicateOK
for i, call := range pcln.InlTree {
// Usually, call.File is already numbered since the file
// shows up in the Pcfile table. However, two inlined calls
// might overlap exactly so that only the innermost file
// appears in the Pcfile table. In that case, this assigns
// the outer file a number.
numberfile(ctxt, call.File)
nameoff := nameToOffset(call.Func.Name)
inlTreeSym.SetUint16(ctxt.Arch, int64(i*20+0), uint16(call.Parent))
inlTreeSym.SetUint8(ctxt.Arch, int64(i*20+2), uint8(objabi.GetFuncID(call.Func.Name, call.Func.File)))
// byte 3 is unused
inlTreeSym.SetUint32(ctxt.Arch, int64(i*20+4), uint32(call.File.Value))
inlTreeSym.SetUint32(ctxt.Arch, int64(i*20+8), uint32(call.Line))
inlTreeSym.SetUint32(ctxt.Arch, int64(i*20+12), uint32(nameoff))
inlTreeSym.SetUint32(ctxt.Arch, int64(i*20+16), uint32(call.ParentPC))
}
pcln.Funcdata[objabi.FUNCDATA_InlTree] = inlTreeSym
pcln.Pcdata[objabi.PCDATA_InlTreeIndex] = pcln.Pcinline
}
// pcdata
off = writepctab(off, pcln.Pcsp.P)
off = writepctab(off, pcln.Pcfile.P)
off = writepctab(off, pcln.Pcline.P)
off = int32(ftab.SetUint32(ctxt.Arch, int64(off), uint32(len(pcln.Pcdata))))
// funcID uint8
var file string
if s.FuncInfo != nil && len(s.FuncInfo.File) > 0 {
file = s.FuncInfo.File[0].Name
}
funcID := objabi.GetFuncID(s.Name, file)
off = int32(ftab.SetUint8(ctxt.Arch, int64(off), uint8(funcID)))
// unused
off += 2
// nfuncdata must be the final entry.
off = int32(ftab.SetUint8(ctxt.Arch, int64(off), uint8(len(pcln.Funcdata))))
for i := range pcln.Pcdata {
off = writepctab(off, pcln.Pcdata[i].P)
}
// funcdata, must be pointer-aligned and we're only int32-aligned.
// Missing funcdata will be 0 (nil pointer).
if len(pcln.Funcdata) > 0 {
if off&int32(ctxt.Arch.PtrSize-1) != 0 {
off += 4
}
for i := range pcln.Funcdata {
dataoff := int64(off) + int64(ctxt.Arch.PtrSize)*int64(i)
if pcln.Funcdata[i] == nil {
ftab.SetUint(ctxt.Arch, dataoff, uint64(pcln.Funcdataoff[i]))
continue
}
// TODO: Dedup.
funcdataBytes += pcln.Funcdata[i].Size
ftab.SetAddrPlus(ctxt.Arch, dataoff, pcln.Funcdata[i], pcln.Funcdataoff[i])
}
off += int32(len(pcln.Funcdata)) * int32(ctxt.Arch.PtrSize)
}
if off != end {
Errorf(s, "bad math in functab: funcstart=%d off=%d but end=%d (npcdata=%d nfuncdata=%d ptrsize=%d)", funcstart, off, end, len(pcln.Pcdata), len(pcln.Funcdata), ctxt.Arch.PtrSize)
errorexit()
}
nfunc++
}
last := ctxt.Textp[len(ctxt.Textp)-1]
pclntabLastFunc = last
// Final entry of table is just end pc.
ftab.SetAddrPlus(ctxt.Arch, 8+int64(ctxt.Arch.PtrSize)+int64(nfunc)*2*int64(ctxt.Arch.PtrSize), last, last.Size)
// Start file table.
start := int32(len(ftab.P))
start += int32(-len(ftab.P)) & (int32(ctxt.Arch.PtrSize) - 1)
pclntabFiletabOffset = start
ftab.SetUint32(ctxt.Arch, 8+int64(ctxt.Arch.PtrSize)+int64(nfunc)*2*int64(ctxt.Arch.PtrSize)+int64(ctxt.Arch.PtrSize), uint32(start))
ftab.Grow(int64(start) + (int64(len(ctxt.Filesyms))+1)*4)
ftab.SetUint32(ctxt.Arch, int64(start), uint32(len(ctxt.Filesyms)+1))
for i := len(ctxt.Filesyms) - 1; i >= 0; i-- {
s := ctxt.Filesyms[i]
ftab.SetUint32(ctxt.Arch, int64(start)+s.Value*4, uint32(ftabaddstring(ftab, s.Name)))
}
ftab.Size = int64(len(ftab.P))
if ctxt.Debugvlog != 0 {
ctxt.Logf("%5.2f pclntab=%d bytes, funcdata total %d bytes\n", Cputime(), ftab.Size, funcdataBytes)
}
}
func gorootFinal() string {
root := objabi.GOROOT
if final := os.Getenv("GOROOT_FINAL"); final != "" {
root = final
}
return root
}
func expandGoroot(s string) string {
const n = len("$GOROOT")
if len(s) >= n+1 && s[:n] == "$GOROOT" && (s[n] == '/' || s[n] == '\\') {
return filepath.ToSlash(filepath.Join(gorootFinal(), s[n:]))
}
return s
}
const (
BUCKETSIZE = 256 * MINFUNC
SUBBUCKETS = 16
SUBBUCKETSIZE = BUCKETSIZE / SUBBUCKETS
NOIDX = 0x7fffffff
)
// findfunctab generates a lookup table to quickly find the containing
// function for a pc. See src/runtime/symtab.go:findfunc for details.
func (ctxt *Link) findfunctab() {
t := ctxt.Syms.Lookup("runtime.findfunctab", 0)
t.Type = sym.SRODATA
t.Attr |= sym.AttrReachable
t.Attr |= sym.AttrLocal
// find min and max address
min := ctxt.Textp[0].Value
lastp := ctxt.Textp[len(ctxt.Textp)-1]
max := lastp.Value + lastp.Size
// for each subbucket, compute the minimum of all symbol indexes
// that map to that subbucket.
n := int32((max - min + SUBBUCKETSIZE - 1) / SUBBUCKETSIZE)
indexes := make([]int32, n)
for i := int32(0); i < n; i++ {
indexes[i] = NOIDX
}
idx := int32(0)
for i, s := range ctxt.Textp {
if !emitPcln(ctxt, s) {
continue
}
p := s.Value
var e *sym.Symbol
i++
if i < len(ctxt.Textp) {
e = ctxt.Textp[i]
}
for !emitPcln(ctxt, e) && i < len(ctxt.Textp) {
e = ctxt.Textp[i]
i++
}
q := max
if e != nil {
q = e.Value
}
//print("%d: [%lld %lld] %s\n", idx, p, q, s->name);
for ; p < q; p += SUBBUCKETSIZE {
i = int((p - min) / SUBBUCKETSIZE)
if indexes[i] > idx {
indexes[i] = idx
}
}
i = int((q - 1 - min) / SUBBUCKETSIZE)
if indexes[i] > idx {
indexes[i] = idx
}
idx++
}
// allocate table
nbuckets := int32((max - min + BUCKETSIZE - 1) / BUCKETSIZE)
t.Grow(4*int64(nbuckets) + int64(n))
// fill in table
for i := int32(0); i < nbuckets; i++ {
base := indexes[i*SUBBUCKETS]
if base == NOIDX {
Errorf(nil, "hole in findfunctab")
}
t.SetUint32(ctxt.Arch, int64(i)*(4+SUBBUCKETS), uint32(base))
for j := int32(0); j < SUBBUCKETS && i*SUBBUCKETS+j < n; j++ {
idx = indexes[i*SUBBUCKETS+j]
if idx == NOIDX {
Errorf(nil, "hole in findfunctab")
}
if idx-base >= 256 {
Errorf(nil, "too many functions in a findfunc bucket! %d/%d %d %d", i, nbuckets, j, idx-base)
}
t.SetUint8(ctxt.Arch, int64(i)*(4+SUBBUCKETS)+4+int64(j), uint8(idx-base))
}
}
}
|
