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-rw-r--r--src/cmd/objdump/main.go519
1 files changed, 519 insertions, 0 deletions
diff --git a/src/cmd/objdump/main.go b/src/cmd/objdump/main.go
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+++ b/src/cmd/objdump/main.go
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+// Copyright 2012 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.
+
+// Objdump disassembles executable files.
+//
+// Usage:
+//
+// go tool objdump [-s symregexp] binary
+//
+// Objdump prints a disassembly of all text symbols (code) in the binary.
+// If the -s option is present, objdump only disassembles
+// symbols with names matching the regular expression.
+//
+// Alternate usage:
+//
+// go tool objdump binary start end
+//
+// In this mode, objdump disassembles the binary starting at the start address and
+// stopping at the end address. The start and end addresses are program
+// counters written in hexadecimal with optional leading 0x prefix.
+// In this mode, objdump prints a sequence of stanzas of the form:
+//
+// file:line
+// address: assembly
+// address: assembly
+// ...
+//
+// Each stanza gives the disassembly for a contiguous range of addresses
+// all mapped to the same original source file and line number.
+// This mode is intended for use by pprof.
+//
+// The ARM disassembler is missing (golang.org/issue/7452) but will be added
+// before the Go 1.3 release.
+package main
+
+import (
+ "bufio"
+ "bytes"
+ "debug/elf"
+ "debug/gosym"
+ "debug/macho"
+ "debug/pe"
+ "debug/plan9obj"
+ "encoding/binary"
+ "flag"
+ "fmt"
+ "io"
+ "log"
+ "os"
+ "regexp"
+ "sort"
+ "strconv"
+ "strings"
+ "text/tabwriter"
+)
+
+var symregexp = flag.String("s", "", "only dump symbols matching this regexp")
+var symRE *regexp.Regexp
+
+func usage() {
+ fmt.Fprintf(os.Stderr, "usage: go tool objdump [-s symregexp] binary [start end]\n\n")
+ flag.PrintDefaults()
+ os.Exit(2)
+}
+
+type lookupFunc func(addr uint64) (sym string, base uint64)
+type disasmFunc func(code []byte, pc uint64, lookup lookupFunc) (text string, size int)
+
+func main() {
+ log.SetFlags(0)
+ log.SetPrefix("objdump: ")
+
+ flag.Usage = usage
+ flag.Parse()
+ if flag.NArg() != 1 && flag.NArg() != 3 {
+ usage()
+ }
+
+ if *symregexp != "" {
+ re, err := regexp.Compile(*symregexp)
+ if err != nil {
+ log.Fatalf("invalid -s regexp: %v", err)
+ }
+ symRE = re
+ }
+
+ f, err := os.Open(flag.Arg(0))
+ if err != nil {
+ log.Fatal(err)
+ }
+
+ textStart, textData, symtab, pclntab, err := loadTables(f)
+ if err != nil {
+ log.Fatalf("reading %s: %v", flag.Arg(0), err)
+ }
+
+ syms, goarch, err := loadSymbols(f)
+ if err != nil {
+ log.Fatalf("reading %s: %v", flag.Arg(0), err)
+ }
+
+ // Filter out section symbols, overwriting syms in place.
+ keep := syms[:0]
+ for _, sym := range syms {
+ switch sym.Name {
+ case "text", "_text", "etext", "_etext":
+ // drop
+ default:
+ keep = append(keep, sym)
+ }
+ }
+ syms = keep
+
+ disasm := disasms[goarch]
+ if disasm == nil {
+ log.Fatalf("reading %s: unknown architecture", flag.Arg(0))
+ }
+
+ lookup := func(addr uint64) (string, uint64) {
+ i := sort.Search(len(syms), func(i int) bool { return syms[i].Addr > addr })
+ if i > 0 {
+ s := syms[i-1]
+ if s.Addr <= addr && addr < s.Addr+uint64(s.Size) && s.Name != "etext" && s.Name != "_etext" {
+ return s.Name, s.Addr
+ }
+ }
+ return "", 0
+ }
+
+ pcln := gosym.NewLineTable(pclntab, textStart)
+ tab, err := gosym.NewTable(symtab, pcln)
+ if err != nil {
+ log.Fatalf("reading %s: %v", flag.Arg(0), err)
+ }
+
+ if flag.NArg() == 1 {
+ // disassembly of entire object - our format
+ dump(tab, lookup, disasm, goarch, syms, textData, textStart)
+ os.Exit(exitCode)
+ }
+
+ // disassembly of specific piece of object - gnu objdump format for pprof
+ gnuDump(tab, lookup, disasm, textData, textStart)
+ os.Exit(exitCode)
+}
+
+// base returns the final element in the path.
+// It works on both Windows and Unix paths.
+func base(path string) string {
+ path = path[strings.LastIndex(path, "/")+1:]
+ path = path[strings.LastIndex(path, `\`)+1:]
+ return path
+}
+
+func dump(tab *gosym.Table, lookup lookupFunc, disasm disasmFunc, goarch string, syms []Sym, textData []byte, textStart uint64) {
+ stdout := bufio.NewWriter(os.Stdout)
+ defer stdout.Flush()
+
+ printed := false
+ for _, sym := range syms {
+ if sym.Code != 'T' || sym.Size == 0 || sym.Name == "_text" || sym.Name == "text" || sym.Addr < textStart || symRE != nil && !symRE.MatchString(sym.Name) {
+ continue
+ }
+ if sym.Addr >= textStart+uint64(len(textData)) || sym.Addr+uint64(sym.Size) > textStart+uint64(len(textData)) {
+ break
+ }
+ if printed {
+ fmt.Fprintf(stdout, "\n")
+ } else {
+ printed = true
+ }
+ file, _, _ := tab.PCToLine(sym.Addr)
+ fmt.Fprintf(stdout, "TEXT %s(SB) %s\n", sym.Name, file)
+ tw := tabwriter.NewWriter(stdout, 1, 8, 1, '\t', 0)
+ start := sym.Addr
+ end := sym.Addr + uint64(sym.Size)
+ for pc := start; pc < end; {
+ i := pc - textStart
+ text, size := disasm(textData[i:end-textStart], pc, lookup)
+ file, line, _ := tab.PCToLine(pc)
+
+ // ARM is word-based, so show actual word hex, not byte hex.
+ // Since ARM is little endian, they're different.
+ if goarch == "arm" && size == 4 {
+ fmt.Fprintf(tw, "\t%s:%d\t%#x\t%08x\t%s\n", base(file), line, pc, binary.LittleEndian.Uint32(textData[i:i+uint64(size)]), text)
+ } else {
+ fmt.Fprintf(tw, "\t%s:%d\t%#x\t%x\t%s\n", base(file), line, pc, textData[i:i+uint64(size)], text)
+ }
+ pc += uint64(size)
+ }
+ tw.Flush()
+ }
+}
+
+func disasm_386(code []byte, pc uint64, lookup lookupFunc) (string, int) {
+ return disasm_x86(code, pc, lookup, 32)
+}
+
+func disasm_amd64(code []byte, pc uint64, lookup lookupFunc) (string, int) {
+ return disasm_x86(code, pc, lookup, 64)
+}
+
+func disasm_x86(code []byte, pc uint64, lookup lookupFunc, arch int) (string, int) {
+ inst, err := x86_Decode(code, 64)
+ var text string
+ size := inst.Len
+ if err != nil || size == 0 || inst.Op == 0 {
+ size = 1
+ text = "?"
+ } else {
+ text = x86_plan9Syntax(inst, pc, lookup)
+ }
+ return text, size
+}
+
+type textReader struct {
+ code []byte
+ pc uint64
+}
+
+func (r textReader) ReadAt(data []byte, off int64) (n int, err error) {
+ if off < 0 || uint64(off) < r.pc {
+ return 0, io.EOF
+ }
+ d := uint64(off) - r.pc
+ if d >= uint64(len(r.code)) {
+ return 0, io.EOF
+ }
+ n = copy(data, r.code[d:])
+ if n < len(data) {
+ err = io.ErrUnexpectedEOF
+ }
+ return
+}
+
+func disasm_arm(code []byte, pc uint64, lookup lookupFunc) (string, int) {
+ inst, err := arm_Decode(code, arm_ModeARM)
+ var text string
+ size := inst.Len
+ if err != nil || size == 0 || inst.Op == 0 {
+ size = 4
+ text = "?"
+ } else {
+ text = arm_plan9Syntax(inst, pc, lookup, textReader{code, pc})
+ }
+ return text, size
+}
+
+var disasms = map[string]disasmFunc{
+ "386": disasm_386,
+ "amd64": disasm_amd64,
+ "arm": disasm_arm,
+}
+
+func gnuDump(tab *gosym.Table, lookup lookupFunc, disasm disasmFunc, textData []byte, textStart uint64) {
+ start, err := strconv.ParseUint(strings.TrimPrefix(flag.Arg(1), "0x"), 16, 64)
+ if err != nil {
+ log.Fatalf("invalid start PC: %v", err)
+ }
+ end, err := strconv.ParseUint(strings.TrimPrefix(flag.Arg(2), "0x"), 16, 64)
+ if err != nil {
+ log.Fatalf("invalid end PC: %v", err)
+ }
+ if start < textStart {
+ start = textStart
+ }
+ if end < start {
+ end = start
+ }
+ if end > textStart+uint64(len(textData)) {
+ end = textStart + uint64(len(textData))
+ }
+
+ stdout := bufio.NewWriter(os.Stdout)
+ defer stdout.Flush()
+
+ // For now, find spans of same PC/line/fn and
+ // emit them as having dummy instructions.
+ var (
+ spanPC uint64
+ spanFile string
+ spanLine int
+ spanFn *gosym.Func
+ )
+
+ flush := func(endPC uint64) {
+ if spanPC == 0 {
+ return
+ }
+ fmt.Fprintf(stdout, "%s:%d\n", spanFile, spanLine)
+ for pc := spanPC; pc < endPC; {
+ text, size := disasm(textData[pc-textStart:], pc, lookup)
+ fmt.Fprintf(stdout, " %x: %s\n", pc, text)
+ pc += uint64(size)
+ }
+ spanPC = 0
+ }
+
+ for pc := start; pc < end; pc++ {
+ file, line, fn := tab.PCToLine(pc)
+ if file != spanFile || line != spanLine || fn != spanFn {
+ flush(pc)
+ spanPC, spanFile, spanLine, spanFn = pc, file, line, fn
+ }
+ }
+ flush(end)
+}
+
+func loadTables(f *os.File) (textStart uint64, textData, symtab, pclntab []byte, err error) {
+ if obj, err := elf.NewFile(f); err == nil {
+ if sect := obj.Section(".text"); sect != nil {
+ textStart = sect.Addr
+ textData, _ = sect.Data()
+ }
+ if sect := obj.Section(".gosymtab"); sect != nil {
+ if symtab, err = sect.Data(); err != nil {
+ return 0, nil, nil, nil, err
+ }
+ }
+ if sect := obj.Section(".gopclntab"); sect != nil {
+ if pclntab, err = sect.Data(); err != nil {
+ return 0, nil, nil, nil, err
+ }
+ }
+ return textStart, textData, symtab, pclntab, nil
+ }
+
+ if obj, err := macho.NewFile(f); err == nil {
+ if sect := obj.Section("__text"); sect != nil {
+ textStart = sect.Addr
+ textData, _ = sect.Data()
+ }
+ if sect := obj.Section("__gosymtab"); sect != nil {
+ if symtab, err = sect.Data(); err != nil {
+ return 0, nil, nil, nil, err
+ }
+ }
+ if sect := obj.Section("__gopclntab"); sect != nil {
+ if pclntab, err = sect.Data(); err != nil {
+ return 0, nil, nil, nil, err
+ }
+ }
+ return textStart, textData, symtab, pclntab, nil
+ }
+
+ if obj, err := pe.NewFile(f); err == nil {
+ var imageBase uint64
+ switch oh := obj.OptionalHeader.(type) {
+ case *pe.OptionalHeader32:
+ imageBase = uint64(oh.ImageBase)
+ case *pe.OptionalHeader64:
+ imageBase = oh.ImageBase
+ default:
+ return 0, nil, nil, nil, fmt.Errorf("pe file format not recognized")
+ }
+ if sect := obj.Section(".text"); sect != nil {
+ textStart = imageBase + uint64(sect.VirtualAddress)
+ textData, _ = sect.Data()
+ }
+ if pclntab, err = loadPETable(obj, "pclntab", "epclntab"); err != nil {
+ return 0, nil, nil, nil, err
+ }
+ if symtab, err = loadPETable(obj, "symtab", "esymtab"); err != nil {
+ return 0, nil, nil, nil, err
+ }
+ return textStart, textData, symtab, pclntab, nil
+ }
+
+ if obj, err := plan9obj.NewFile(f); err == nil {
+ sym, err := findPlan9Symbol(obj, "text")
+ if err != nil {
+ return 0, nil, nil, nil, err
+ }
+ textStart = sym.Value
+ if sect := obj.Section("text"); sect != nil {
+ textData, _ = sect.Data()
+ }
+ if pclntab, err = loadPlan9Table(obj, "pclntab", "epclntab"); err != nil {
+ return 0, nil, nil, nil, err
+ }
+ if symtab, err = loadPlan9Table(obj, "symtab", "esymtab"); err != nil {
+ return 0, nil, nil, nil, err
+ }
+ return textStart, textData, symtab, pclntab, nil
+ }
+
+ return 0, nil, nil, nil, fmt.Errorf("unrecognized binary format")
+}
+
+func findPESymbol(f *pe.File, name string) (*pe.Symbol, error) {
+ for _, s := range f.Symbols {
+ if s.Name != name {
+ continue
+ }
+ if s.SectionNumber <= 0 {
+ return nil, fmt.Errorf("symbol %s: invalid section number %d", name, s.SectionNumber)
+ }
+ if len(f.Sections) < int(s.SectionNumber) {
+ return nil, fmt.Errorf("symbol %s: section number %d is larger than max %d", name, s.SectionNumber, len(f.Sections))
+ }
+ return s, nil
+ }
+ return nil, fmt.Errorf("no %s symbol found", name)
+}
+
+func loadPETable(f *pe.File, sname, ename string) ([]byte, error) {
+ ssym, err := findPESymbol(f, sname)
+ if err != nil {
+ return nil, err
+ }
+ esym, err := findPESymbol(f, ename)
+ if err != nil {
+ return nil, err
+ }
+ if ssym.SectionNumber != esym.SectionNumber {
+ return nil, fmt.Errorf("%s and %s symbols must be in the same section", sname, ename)
+ }
+ sect := f.Sections[ssym.SectionNumber-1]
+ data, err := sect.Data()
+ if err != nil {
+ return nil, err
+ }
+ return data[ssym.Value:esym.Value], nil
+}
+
+func findPlan9Symbol(f *plan9obj.File, name string) (*plan9obj.Sym, error) {
+ syms, err := f.Symbols()
+ if err != nil {
+ return nil, err
+ }
+ for _, s := range syms {
+ if s.Name != name {
+ continue
+ }
+ return &s, nil
+ }
+ return nil, fmt.Errorf("no %s symbol found", name)
+}
+
+func loadPlan9Table(f *plan9obj.File, sname, ename string) ([]byte, error) {
+ ssym, err := findPlan9Symbol(f, sname)
+ if err != nil {
+ return nil, err
+ }
+ esym, err := findPlan9Symbol(f, ename)
+ if err != nil {
+ return nil, err
+ }
+ text, err := findPlan9Symbol(f, "text")
+ if err != nil {
+ return nil, err
+ }
+ sect := f.Section("text")
+ if sect == nil {
+ return nil, err
+ }
+ data, err := sect.Data()
+ if err != nil {
+ return nil, err
+ }
+ return data[ssym.Value-text.Value : esym.Value-text.Value], nil
+}
+
+// TODO(rsc): This code is taken from cmd/nm. Arrange some way to share the code.
+
+var exitCode = 0
+
+func errorf(format string, args ...interface{}) {
+ log.Printf(format, args...)
+ exitCode = 1
+}
+
+func loadSymbols(f *os.File) (syms []Sym, goarch string, err error) {
+ f.Seek(0, 0)
+ buf := make([]byte, 16)
+ io.ReadFull(f, buf)
+ f.Seek(0, 0)
+
+ for _, p := range parsers {
+ if bytes.HasPrefix(buf, p.prefix) {
+ syms, goarch = p.parse(f)
+ sort.Sort(byAddr(syms))
+ return
+ }
+ }
+ err = fmt.Errorf("unknown file format")
+ return
+}
+
+type Sym struct {
+ Addr uint64
+ Size int64
+ Code rune
+ Name string
+ Type string
+}
+
+var parsers = []struct {
+ prefix []byte
+ parse func(*os.File) ([]Sym, string)
+}{
+ {[]byte("\x7FELF"), elfSymbols},
+ {[]byte("\xFE\xED\xFA\xCE"), machoSymbols},
+ {[]byte("\xFE\xED\xFA\xCF"), machoSymbols},
+ {[]byte("\xCE\xFA\xED\xFE"), machoSymbols},
+ {[]byte("\xCF\xFA\xED\xFE"), machoSymbols},
+ {[]byte("MZ"), peSymbols},
+ {[]byte("\x00\x00\x01\xEB"), plan9Symbols}, // 386
+ {[]byte("\x00\x00\x04\x07"), plan9Symbols}, // mips
+ {[]byte("\x00\x00\x06\x47"), plan9Symbols}, // arm
+ {[]byte("\x00\x00\x8A\x97"), plan9Symbols}, // amd64
+}
+
+type byAddr []Sym
+
+func (x byAddr) Len() int { return len(x) }
+func (x byAddr) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
+func (x byAddr) Less(i, j int) bool { return x[i].Addr < x[j].Addr }
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