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Diffstat (limited to 'src/cmd/internal/objfile/disasm.go')
| -rw-r--r-- | src/cmd/internal/objfile/disasm.go | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/src/cmd/internal/objfile/disasm.go b/src/cmd/internal/objfile/disasm.go new file mode 100644 index 000000000..1a339c321 --- /dev/null +++ b/src/cmd/internal/objfile/disasm.go @@ -0,0 +1,248 @@ +// Copyright 2014 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 objfile + +import ( + "bufio" + "debug/gosym" + "encoding/binary" + "fmt" + "io" + "regexp" + "sort" + "strings" + "text/tabwriter" + + "cmd/internal/rsc.io/arm/armasm" + "cmd/internal/rsc.io/x86/x86asm" +) + +// Disasm is a disassembler for a given File. +type Disasm struct { + syms []Sym //symbols in file, sorted by address + pcln *gosym.Table // pcln table + text []byte // bytes of text segment (actual instructions) + textStart uint64 // start PC of text + textEnd uint64 // end PC of text + goarch string // GOARCH string + disasm disasmFunc // disassembler function for goarch + byteOrder binary.ByteOrder // byte order for goarch +} + +// Disasm returns a disassembler for the file f. +func (f *File) Disasm() (*Disasm, error) { + syms, err := f.Symbols() + if err != nil { + return nil, err + } + + pcln, err := f.PCLineTable() + if err != nil { + return nil, err + } + + textStart, textBytes, err := f.Text() + if err != nil { + return nil, err + } + + goarch := f.GOARCH() + disasm := disasms[goarch] + byteOrder := byteOrders[goarch] + if disasm == nil || byteOrder == nil { + return nil, fmt.Errorf("unsupported architecture") + } + + // Filter out section symbols, overwriting syms in place. + keep := syms[:0] + for _, sym := range syms { + switch sym.Name { + case "runtime.text", "text", "_text", "runtime.etext", "etext", "_etext": + // drop + default: + keep = append(keep, sym) + } + } + syms = keep + d := &Disasm{ + syms: syms, + pcln: pcln, + text: textBytes, + textStart: textStart, + textEnd: textStart + uint64(len(textBytes)), + goarch: goarch, + disasm: disasm, + byteOrder: byteOrder, + } + + return d, nil +} + +// lookup finds the symbol name containing addr. +func (d *Disasm) lookup(addr uint64) (name string, base uint64) { + i := sort.Search(len(d.syms), func(i int) bool { return addr < d.syms[i].Addr }) + if i > 0 { + s := d.syms[i-1] + if s.Addr != 0 && s.Addr <= addr && addr < s.Addr+uint64(s.Size) { + return s.Name, s.Addr + } + } + return "", 0 +} + +// base returns the final element in the path. +// It works on both Windows and Unix paths, +// regardless of host operating system. +func base(path string) string { + path = path[strings.LastIndex(path, "/")+1:] + path = path[strings.LastIndex(path, `\`)+1:] + return path +} + +// Print prints a disassembly of the file to w. +// If filter is non-nil, the disassembly only includes functions with names matching filter. +// The disassembly only includes functions that overlap the range [start, end). +func (d *Disasm) Print(w io.Writer, filter *regexp.Regexp, start, end uint64) { + if start < d.textStart { + start = d.textStart + } + if end > d.textEnd { + end = d.textEnd + } + printed := false + bw := bufio.NewWriter(w) + for _, sym := range d.syms { + symStart := sym.Addr + symEnd := sym.Addr + uint64(sym.Size) + if sym.Code != 'T' && sym.Code != 't' || + symStart < d.textStart || + symEnd <= start || end <= symStart || + filter != nil && !filter.MatchString(sym.Name) { + continue + } + if printed { + fmt.Fprintf(bw, "\n") + } + printed = true + + file, _, _ := d.pcln.PCToLine(sym.Addr) + fmt.Fprintf(bw, "TEXT %s(SB) %s\n", sym.Name, file) + + tw := tabwriter.NewWriter(bw, 1, 8, 1, '\t', 0) + if symEnd > end { + symEnd = end + } + code := d.text[:end-d.textStart] + d.Decode(symStart, symEnd, func(pc, size uint64, file string, line int, text string) { + i := pc - d.textStart + fmt.Fprintf(tw, "\t%s:%d\t%#x\t", base(file), line, pc) + if size%4 != 0 || d.goarch == "386" || d.goarch == "amd64" { + // Print instruction as bytes. + fmt.Fprintf(tw, "%x", code[i:i+size]) + } else { + // Print instruction as 32-bit words. + for j := uint64(0); j < size; j += 4 { + if j > 0 { + fmt.Fprintf(tw, " ") + } + fmt.Fprintf(tw, "%08x", d.byteOrder.Uint32(code[i+j:])) + } + } + fmt.Fprintf(tw, "\t%s\n", text) + }) + tw.Flush() + } + bw.Flush() +} + +// Decode disassembles the text segment range [start, end), calling f for each instruction. +func (d *Disasm) Decode(start, end uint64, f func(pc, size uint64, file string, line int, text string)) { + if start < d.textStart { + start = d.textStart + } + if end > d.textEnd { + end = d.textEnd + } + code := d.text[:end-d.textStart] + lookup := d.lookup + for pc := start; pc < end; { + i := pc - d.textStart + text, size := d.disasm(code[i:], pc, lookup) + file, line, _ := d.pcln.PCToLine(pc) + f(pc, uint64(size), file, line, text) + pc += uint64(size) + } +} + +type lookupFunc func(addr uint64) (sym string, base uint64) +type disasmFunc func(code []byte, pc uint64, lookup lookupFunc) (text string, size int) + +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 := x86asm.Decode(code, 64) + var text string + size := inst.Len + if err != nil || size == 0 || inst.Op == 0 { + size = 1 + text = "?" + } else { + text = x86asm.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 := armasm.Decode(code, armasm.ModeARM) + var text string + size := inst.Len + if err != nil || size == 0 || inst.Op == 0 { + size = 4 + text = "?" + } else { + text = armasm.Plan9Syntax(inst, pc, lookup, textReader{code, pc}) + } + return text, size +} + +var disasms = map[string]disasmFunc{ + "386": disasm_386, + "amd64": disasm_amd64, + "arm": disasm_arm, +} + +var byteOrders = map[string]binary.ByteOrder{ + "386": binary.LittleEndian, + "amd64": binary.LittleEndian, + "arm": binary.LittleEndian, + "power64": binary.BigEndian, + "power64le": binary.LittleEndian, +} |