Example #1
0
func writeinfo(ctxt *Link, syms []*Symbol, funcs []*Symbol) []*Symbol {
	if infosec == nil {
		infosec = Linklookup(ctxt, ".debug_info", 0)
	}
	infosec.R = infosec.R[:0]
	infosec.Type = obj.SDWARFINFO
	infosec.Attr |= AttrReachable
	syms = append(syms, infosec)

	if arangessec == nil {
		arangessec = Linklookup(ctxt, ".dwarfaranges", 0)
	}
	arangessec.R = arangessec.R[:0]

	var dwarfctxt dwarf.Context = dwctxt{ctxt}

	for compunit := dwroot.Child; compunit != nil; compunit = compunit.Link {
		s := dtolsym(compunit.Sym)

		// Write .debug_info Compilation Unit Header (sec 7.5.1)
		// Fields marked with (*) must be changed for 64-bit dwarf
		// This must match COMPUNITHEADERSIZE above.
		Adduint32(ctxt, s, 0) // unit_length (*), will be filled in later.
		Adduint16(ctxt, s, 2) // dwarf version (appendix F)

		// debug_abbrev_offset (*)
		adddwarfref(ctxt, s, abbrevsym, 4)

		Adduint8(ctxt, s, uint8(SysArch.PtrSize)) // address_size

		dwarf.Uleb128put(dwarfctxt, s, int64(compunit.Abbrev))
		dwarf.PutAttrs(dwarfctxt, s, compunit.Abbrev, compunit.Attr)

		cu := []*Symbol{s}
		if funcs != nil {
			cu = append(cu, funcs...)
			funcs = nil
		}
		cu = putdies(ctxt, dwarfctxt, cu, compunit.Child)
		var cusize int64
		for _, child := range cu {
			cusize += child.Size
		}
		cusize -= 4 // exclude the length field.
		setuint32(ctxt, s, 0, uint32(cusize))
		newattr(compunit, dwarf.DW_AT_byte_size, dwarf.DW_CLS_CONSTANT, cusize, 0)
		syms = append(syms, cu...)
	}
	return syms
}
Example #2
0
func putdie(linkctxt *Link, ctxt dwarf.Context, syms []*Symbol, die *dwarf.DWDie) []*Symbol {
	s := dtolsym(die.Sym)
	if s == nil {
		s = syms[len(syms)-1]
	} else {
		if s.Attr.OnList() {
			log.Fatalf("symbol %s listed multiple times", s.Name)
		}
		s.Attr |= AttrOnList
		syms = append(syms, s)
	}
	dwarf.Uleb128put(ctxt, s, int64(die.Abbrev))
	dwarf.PutAttrs(ctxt, s, die.Abbrev, die.Attr)
	if dwarf.HasChildren(die) {
		return putdies(linkctxt, ctxt, syms, die.Child)
	}
	return syms
}
Example #3
0
func writelines(ctxt *Link, syms []*Symbol) ([]*Symbol, []*Symbol) {
	var dwarfctxt dwarf.Context = dwctxt{ctxt}
	if linesec == nil {
		linesec = Linklookup(ctxt, ".debug_line", 0)
	}
	linesec.Type = obj.SDWARFSECT
	linesec.R = linesec.R[:0]

	ls := linesec
	syms = append(syms, ls)
	var funcs []*Symbol

	unitstart := int64(-1)
	headerstart := int64(-1)
	headerend := int64(-1)
	epc := int64(0)
	var epcs *Symbol
	var dwinfo *dwarf.DWDie

	lang := dwarf.DW_LANG_Go

	s := ctxt.Textp[0]

	dwinfo = newdie(ctxt, &dwroot, dwarf.DW_ABRV_COMPUNIT, "go", 0)
	newattr(dwinfo, dwarf.DW_AT_language, dwarf.DW_CLS_CONSTANT, int64(lang), 0)
	newattr(dwinfo, dwarf.DW_AT_stmt_list, dwarf.DW_CLS_PTR, 0, linesec)
	newattr(dwinfo, dwarf.DW_AT_low_pc, dwarf.DW_CLS_ADDRESS, s.Value, s)
	// OS X linker requires compilation dir or absolute path in comp unit name to output debug info.
	compDir := getCompilationDir()
	newattr(dwinfo, dwarf.DW_AT_comp_dir, dwarf.DW_CLS_STRING, int64(len(compDir)), compDir)

	// Write .debug_line Line Number Program Header (sec 6.2.4)
	// Fields marked with (*) must be changed for 64-bit dwarf
	unit_length_offset := ls.Size
	Adduint32(ctxt, ls, 0) // unit_length (*), filled in at end.
	unitstart = ls.Size
	Adduint16(ctxt, ls, 2) // dwarf version (appendix F)
	header_length_offset := ls.Size
	Adduint32(ctxt, ls, 0) // header_length (*), filled in at end.
	headerstart = ls.Size

	// cpos == unitstart + 4 + 2 + 4
	Adduint8(ctxt, ls, 1)              // minimum_instruction_length
	Adduint8(ctxt, ls, 1)              // default_is_stmt
	Adduint8(ctxt, ls, LINE_BASE&0xFF) // line_base
	Adduint8(ctxt, ls, LINE_RANGE)     // line_range
	Adduint8(ctxt, ls, OPCODE_BASE)    // opcode_base
	Adduint8(ctxt, ls, 0)              // standard_opcode_lengths[1]
	Adduint8(ctxt, ls, 1)              // standard_opcode_lengths[2]
	Adduint8(ctxt, ls, 1)              // standard_opcode_lengths[3]
	Adduint8(ctxt, ls, 1)              // standard_opcode_lengths[4]
	Adduint8(ctxt, ls, 1)              // standard_opcode_lengths[5]
	Adduint8(ctxt, ls, 0)              // standard_opcode_lengths[6]
	Adduint8(ctxt, ls, 0)              // standard_opcode_lengths[7]
	Adduint8(ctxt, ls, 0)              // standard_opcode_lengths[8]
	Adduint8(ctxt, ls, 1)              // standard_opcode_lengths[9]
	Adduint8(ctxt, ls, 0)              // include_directories  (empty)

	for _, f := range ctxt.Filesyms {
		Addstring(ctxt, ls, f.Name)
		Adduint8(ctxt, ls, 0)
		Adduint8(ctxt, ls, 0)
		Adduint8(ctxt, ls, 0)
	}

	// 4 zeros: the string termination + 3 fields.
	Adduint8(ctxt, ls, 0)
	// terminate file_names.
	headerend = ls.Size

	Adduint8(ctxt, ls, 0) // start extended opcode
	dwarf.Uleb128put(dwarfctxt, ls, 1+int64(SysArch.PtrSize))
	Adduint8(ctxt, ls, dwarf.DW_LNE_set_address)

	pc := s.Value
	line := 1
	file := 1
	Addaddr(ctxt, ls, s)

	var pcfile Pciter
	var pcline Pciter
	for _, ctxt.Cursym = range ctxt.Textp {
		s := ctxt.Cursym

		epc = s.Value + s.Size
		epcs = s

		dsym := Linklookup(ctxt, dwarf.InfoPrefix+s.Name, int(s.Version))
		dsym.Attr |= AttrHidden
		dsym.Type = obj.SDWARFINFO
		for _, r := range dsym.R {
			if r.Type == obj.R_DWARFREF && r.Sym.Size == 0 {
				if Buildmode == BuildmodeShared {
					// These type symbols may not be present in BuildmodeShared. Skip.
					continue
				}
				n := nameFromDIESym(r.Sym)
				defgotype(ctxt, Linklookup(ctxt, "type."+n, 0))
			}
		}
		funcs = append(funcs, dsym)

		if s.FuncInfo == nil {
			continue
		}

		finddebugruntimepath(s)

		pciterinit(ctxt, &pcfile, &s.FuncInfo.Pcfile)
		pciterinit(ctxt, &pcline, &s.FuncInfo.Pcline)
		epc = pc
		for pcfile.done == 0 && pcline.done == 0 {
			if epc-s.Value >= int64(pcfile.nextpc) {
				pciternext(&pcfile)
				continue
			}

			if epc-s.Value >= int64(pcline.nextpc) {
				pciternext(&pcline)
				continue
			}

			if int32(file) != pcfile.value {
				Adduint8(ctxt, ls, dwarf.DW_LNS_set_file)
				dwarf.Uleb128put(dwarfctxt, ls, int64(pcfile.value))
				file = int(pcfile.value)
			}

			putpclcdelta(ctxt, dwarfctxt, ls, s.Value+int64(pcline.pc)-pc, int64(pcline.value)-int64(line))

			pc = s.Value + int64(pcline.pc)
			line = int(pcline.value)
			if pcfile.nextpc < pcline.nextpc {
				epc = int64(pcfile.nextpc)
			} else {
				epc = int64(pcline.nextpc)
			}
			epc += s.Value
		}
	}

	Adduint8(ctxt, ls, 0) // start extended opcode
	dwarf.Uleb128put(dwarfctxt, ls, 1)
	Adduint8(ctxt, ls, dwarf.DW_LNE_end_sequence)

	newattr(dwinfo, dwarf.DW_AT_high_pc, dwarf.DW_CLS_ADDRESS, epc+1, epcs)

	setuint32(ctxt, ls, unit_length_offset, uint32(ls.Size-unitstart))
	setuint32(ctxt, ls, header_length_offset, uint32(headerend-headerstart))

	return syms, funcs
}
Example #4
0
func writeframes(ctxt *Link, syms []*Symbol) []*Symbol {
	var dwarfctxt dwarf.Context = dwctxt{ctxt}
	if framesec == nil {
		framesec = Linklookup(ctxt, ".debug_frame", 0)
	}
	framesec.Type = obj.SDWARFSECT
	framesec.R = framesec.R[:0]
	fs := framesec
	syms = append(syms, fs)

	// Emit the CIE, Section 6.4.1
	cieReserve := uint32(16)
	if haslinkregister(ctxt) {
		cieReserve = 32
	}
	Adduint32(ctxt, fs, cieReserve)                            // initial length, must be multiple of thearch.ptrsize
	Adduint32(ctxt, fs, 0xffffffff)                            // cid.
	Adduint8(ctxt, fs, 3)                                      // dwarf version (appendix F)
	Adduint8(ctxt, fs, 0)                                      // augmentation ""
	dwarf.Uleb128put(dwarfctxt, fs, 1)                         // code_alignment_factor
	dwarf.Sleb128put(dwarfctxt, fs, dataAlignmentFactor)       // all CFI offset calculations include multiplication with this factor
	dwarf.Uleb128put(dwarfctxt, fs, int64(Thearch.Dwarfreglr)) // return_address_register

	Adduint8(ctxt, fs, dwarf.DW_CFA_def_cfa)                   // Set the current frame address..
	dwarf.Uleb128put(dwarfctxt, fs, int64(Thearch.Dwarfregsp)) // ...to use the value in the platform's SP register (defined in l.go)...
	if haslinkregister(ctxt) {
		dwarf.Uleb128put(dwarfctxt, fs, int64(0)) // ...plus a 0 offset.

		Adduint8(ctxt, fs, dwarf.DW_CFA_same_value) // The platform's link register is unchanged during the prologue.
		dwarf.Uleb128put(dwarfctxt, fs, int64(Thearch.Dwarfreglr))

		Adduint8(ctxt, fs, dwarf.DW_CFA_val_offset)                // The previous value...
		dwarf.Uleb128put(dwarfctxt, fs, int64(Thearch.Dwarfregsp)) // ...of the platform's SP register...
		dwarf.Uleb128put(dwarfctxt, fs, int64(0))                  // ...is CFA+0.
	} else {
		dwarf.Uleb128put(dwarfctxt, fs, int64(SysArch.PtrSize)) // ...plus the word size (because the call instruction implicitly adds one word to the frame).

		Adduint8(ctxt, fs, dwarf.DW_CFA_offset_extended)                             // The previous value...
		dwarf.Uleb128put(dwarfctxt, fs, int64(Thearch.Dwarfreglr))                   // ...of the return address...
		dwarf.Uleb128put(dwarfctxt, fs, int64(-SysArch.PtrSize)/dataAlignmentFactor) // ...is saved at [CFA - (PtrSize/4)].
	}

	// 4 is to exclude the length field.
	pad := int64(cieReserve) + 4 - fs.Size

	if pad < 0 {
		Exitf("dwarf: cieReserve too small by %d bytes.", -pad)
	}

	Addbytes(ctxt, fs, zeros[:pad])

	var deltaBuf []byte
	var pcsp Pciter
	for _, ctxt.Cursym = range ctxt.Textp {
		s := ctxt.Cursym
		if s.FuncInfo == nil {
			continue
		}

		// Emit a FDE, Section 6.4.1.
		// First build the section contents into a byte buffer.
		deltaBuf = deltaBuf[:0]
		for pciterinit(ctxt, &pcsp, &s.FuncInfo.Pcsp); pcsp.done == 0; pciternext(&pcsp) {
			nextpc := pcsp.nextpc

			// pciterinit goes up to the end of the function,
			// but DWARF expects us to stop just before the end.
			if int64(nextpc) == s.Size {
				nextpc--
				if nextpc < pcsp.pc {
					continue
				}
			}

			if haslinkregister(ctxt) {
				// TODO(bryanpkc): This is imprecise. In general, the instruction
				// that stores the return address to the stack frame is not the
				// same one that allocates the frame.
				if pcsp.value > 0 {
					// The return address is preserved at (CFA-frame_size)
					// after a stack frame has been allocated.
					deltaBuf = append(deltaBuf, dwarf.DW_CFA_offset_extended_sf)
					deltaBuf = dwarf.AppendUleb128(deltaBuf, uint64(Thearch.Dwarfreglr))
					deltaBuf = dwarf.AppendSleb128(deltaBuf, -int64(pcsp.value)/dataAlignmentFactor)
				} else {
					// The return address is restored into the link register
					// when a stack frame has been de-allocated.
					deltaBuf = append(deltaBuf, dwarf.DW_CFA_same_value)
					deltaBuf = dwarf.AppendUleb128(deltaBuf, uint64(Thearch.Dwarfreglr))
				}
				deltaBuf = appendPCDeltaCFA(deltaBuf, int64(nextpc)-int64(pcsp.pc), int64(pcsp.value))
			} else {
				deltaBuf = appendPCDeltaCFA(deltaBuf, int64(nextpc)-int64(pcsp.pc), int64(SysArch.PtrSize)+int64(pcsp.value))
			}
		}
		pad := int(Rnd(int64(len(deltaBuf)), int64(SysArch.PtrSize))) - len(deltaBuf)
		deltaBuf = append(deltaBuf, zeros[:pad]...)

		// Emit the FDE header, Section 6.4.1.
		//	4 bytes: length, must be multiple of thearch.ptrsize
		//	4 bytes: Pointer to the CIE above, at offset 0
		//	ptrsize: initial location
		//	ptrsize: address range
		Adduint32(ctxt, fs, uint32(4+2*SysArch.PtrSize+len(deltaBuf))) // length (excludes itself)
		if Linkmode == LinkExternal {
			adddwarfref(ctxt, fs, framesec, 4)
		} else {
			Adduint32(ctxt, fs, 0) // CIE offset
		}
		Addaddr(ctxt, fs, s)
		adduintxx(ctxt, fs, uint64(s.Size), SysArch.PtrSize) // address range
		Addbytes(ctxt, fs, deltaBuf)
	}
	return syms
}
Example #5
0
File: dwarf.go Project: achanda/go
func putpclcdelta(linkctxt *Link, ctxt dwarf.Context, s *Symbol, deltaPC uint64, deltaLC int64) {
	// Choose a special opcode that minimizes the number of bytes needed to
	// encode the remaining PC delta and LC delta.
	var opcode int64
	if deltaLC < LINE_BASE {
		if deltaPC >= PC_RANGE {
			opcode = OPCODE_BASE + (LINE_RANGE * PC_RANGE)
		} else {
			opcode = OPCODE_BASE + (LINE_RANGE * int64(deltaPC))
		}
	} else if deltaLC < LINE_BASE+LINE_RANGE {
		if deltaPC >= PC_RANGE {
			opcode = OPCODE_BASE + (deltaLC - LINE_BASE) + (LINE_RANGE * PC_RANGE)
			if opcode > 255 {
				opcode -= LINE_RANGE
			}
		} else {
			opcode = OPCODE_BASE + (deltaLC - LINE_BASE) + (LINE_RANGE * int64(deltaPC))
		}
	} else {
		if deltaPC <= PC_RANGE {
			opcode = OPCODE_BASE + (LINE_RANGE - 1) + (LINE_RANGE * int64(deltaPC))
			if opcode > 255 {
				opcode = 255
			}
		} else {
			// Use opcode 249 (pc+=23, lc+=5) or 255 (pc+=24, lc+=1).
			//
			// Let x=deltaPC-PC_RANGE.  If we use opcode 255, x will be the remaining
			// deltaPC that we need to encode separately before emitting 255.  If we
			// use opcode 249, we will need to encode x+1.  If x+1 takes one more
			// byte to encode than x, then we use opcode 255.
			//
			// In all other cases x and x+1 take the same number of bytes to encode,
			// so we use opcode 249, which may save us a byte in encoding deltaLC,
			// for similar reasons.
			switch deltaPC - PC_RANGE {
			// PC_RANGE is the largest deltaPC we can encode in one byte, using
			// DW_LNS_const_add_pc.
			//
			// (1<<16)-1 is the largest deltaPC we can encode in three bytes, using
			// DW_LNS_fixed_advance_pc.
			//
			// (1<<(7n))-1 is the largest deltaPC we can encode in n+1 bytes for
			// n=1,3,4,5,..., using DW_LNS_advance_pc.
			case PC_RANGE, (1 << 7) - 1, (1 << 16) - 1, (1 << 21) - 1, (1 << 28) - 1,
				(1 << 35) - 1, (1 << 42) - 1, (1 << 49) - 1, (1 << 56) - 1, (1 << 63) - 1:
				opcode = 255
			default:
				opcode = OPCODE_BASE + LINE_RANGE*PC_RANGE - 1 // 249
			}
		}
	}
	if opcode < OPCODE_BASE || opcode > 255 {
		panic(fmt.Sprintf("produced invalid special opcode %d", opcode))
	}

	// Subtract from deltaPC and deltaLC the amounts that the opcode will add.
	deltaPC -= uint64((opcode - OPCODE_BASE) / LINE_RANGE)
	deltaLC -= int64((opcode-OPCODE_BASE)%LINE_RANGE + LINE_BASE)

	// Encode deltaPC.
	if deltaPC != 0 {
		if deltaPC <= PC_RANGE {
			// Adjust the opcode so that we can use the 1-byte DW_LNS_const_add_pc
			// instruction.
			opcode -= LINE_RANGE * int64(PC_RANGE-deltaPC)
			if opcode < OPCODE_BASE {
				panic(fmt.Sprintf("produced invalid special opcode %d", opcode))
			}
			Adduint8(linkctxt, s, dwarf.DW_LNS_const_add_pc)
		} else if (1<<14) <= deltaPC && deltaPC < (1<<16) {
			Adduint8(linkctxt, s, dwarf.DW_LNS_fixed_advance_pc)
			Adduint16(linkctxt, s, uint16(deltaPC))
		} else {
			Adduint8(linkctxt, s, dwarf.DW_LNS_advance_pc)
			dwarf.Uleb128put(ctxt, s, int64(deltaPC))
		}
	}

	// Encode deltaLC.
	if deltaLC != 0 {
		Adduint8(linkctxt, s, dwarf.DW_LNS_advance_line)
		dwarf.Sleb128put(ctxt, s, deltaLC)
	}

	// Output the special opcode.
	Adduint8(linkctxt, s, uint8(opcode))
}