Пример #1
0
func elfsetupplt() {
	plt := ld.Linklookup(ld.Ctxt, ".plt", 0)
	got := ld.Linklookup(ld.Ctxt, ".got.plt", 0)
	if plt.Size == 0 {
		// pushl got+4
		ld.Adduint8(ld.Ctxt, plt, 0xff)

		ld.Adduint8(ld.Ctxt, plt, 0x35)
		ld.Addaddrplus(ld.Ctxt, plt, got, 4)

		// jmp *got+8
		ld.Adduint8(ld.Ctxt, plt, 0xff)

		ld.Adduint8(ld.Ctxt, plt, 0x25)
		ld.Addaddrplus(ld.Ctxt, plt, got, 8)

		// zero pad
		ld.Adduint32(ld.Ctxt, plt, 0)

		// assume got->size == 0 too
		ld.Addaddrplus(ld.Ctxt, got, ld.Linklookup(ld.Ctxt, ".dynamic", 0), 0)

		ld.Adduint32(ld.Ctxt, got, 0)
		ld.Adduint32(ld.Ctxt, got, 0)
	}
}
Пример #2
0
Файл: asm.go Проект: achanda/go
func elfsetupplt(ctxt *ld.Link) {
	plt := ctxt.Syms.Lookup(".plt", 0)
	got := ctxt.Syms.Lookup(".got.plt", 0)
	if plt.Size == 0 {
		// pushl got+4
		ld.Adduint8(ctxt, plt, 0xff)

		ld.Adduint8(ctxt, plt, 0x35)
		ld.Addaddrplus(ctxt, plt, got, 4)

		// jmp *got+8
		ld.Adduint8(ctxt, plt, 0xff)

		ld.Adduint8(ctxt, plt, 0x25)
		ld.Addaddrplus(ctxt, plt, got, 8)

		// zero pad
		ld.Adduint32(ctxt, plt, 0)

		// assume got->size == 0 too
		ld.Addaddrplus(ctxt, got, ctxt.Syms.Lookup(".dynamic", 0), 0)

		ld.Adduint32(ctxt, got, 0)
		ld.Adduint32(ctxt, got, 0)
	}
}
Пример #3
0
func addpltsym(ctxt *ld.Link, s *ld.LSym) {
	if s.Plt >= 0 {
		return
	}

	ld.Adddynsym(ctxt, s)

	if ld.Iself {
		plt := ld.Linklookup(ctxt, ".plt", 0)
		got := ld.Linklookup(ctxt, ".got.plt", 0)
		rel := ld.Linklookup(ctxt, ".rel.plt", 0)
		if plt.Size == 0 {
			elfsetupplt()
		}

		// jmpq *got+size
		ld.Adduint8(ctxt, plt, 0xff)

		ld.Adduint8(ctxt, plt, 0x25)
		ld.Addaddrplus(ctxt, plt, got, got.Size)

		// add to got: pointer to current pos in plt
		ld.Addaddrplus(ctxt, got, plt, plt.Size)

		// pushl $x
		ld.Adduint8(ctxt, plt, 0x68)

		ld.Adduint32(ctxt, plt, uint32(rel.Size))

		// jmp .plt
		ld.Adduint8(ctxt, plt, 0xe9)

		ld.Adduint32(ctxt, plt, uint32(-(plt.Size + 4)))

		// rel
		ld.Addaddrplus(ctxt, rel, got, got.Size-4)

		ld.Adduint32(ctxt, rel, ld.ELF32_R_INFO(uint32(s.Dynid), ld.R_386_JMP_SLOT))

		s.Plt = int32(plt.Size - 16)
	} else if ld.HEADTYPE == obj.Hdarwin {
		// Same laziness as in 6l.

		plt := ld.Linklookup(ctxt, ".plt", 0)

		addgotsym(ctxt, s)

		ld.Adduint32(ctxt, ld.Linklookup(ctxt, ".linkedit.plt", 0), uint32(s.Dynid))

		// jmpq *got+size(IP)
		s.Plt = int32(plt.Size)

		ld.Adduint8(ctxt, plt, 0xff)
		ld.Adduint8(ctxt, plt, 0x25)
		ld.Addaddrplus(ctxt, plt, ld.Linklookup(ctxt, ".got", 0), int64(s.Got))
	} else {
		ld.Diag("addpltsym: unsupported binary format")
	}
}
Пример #4
0
Файл: asm.go Проект: sreis/go
func elfsetupplt() {
	plt := ld.Linklookup(ld.Ctxt, ".plt", 0)
	got := ld.Linklookup(ld.Ctxt, ".got.plt", 0)
	if plt.Size == 0 {
		// pushq got+8(IP)
		ld.Adduint8(ld.Ctxt, plt, 0xff)

		ld.Adduint8(ld.Ctxt, plt, 0x35)
		ld.Addpcrelplus(ld.Ctxt, plt, got, 8)

		// jmpq got+16(IP)
		ld.Adduint8(ld.Ctxt, plt, 0xff)

		ld.Adduint8(ld.Ctxt, plt, 0x25)
		ld.Addpcrelplus(ld.Ctxt, plt, got, 16)

		// nopl 0(AX)
		ld.Adduint32(ld.Ctxt, plt, 0x00401f0f)

		// assume got->size == 0 too
		ld.Addaddrplus(ld.Ctxt, got, ld.Linklookup(ld.Ctxt, ".dynamic", 0), 0)

		ld.Adduint64(ld.Ctxt, got, 0)
		ld.Adduint64(ld.Ctxt, got, 0)
	}
}
Пример #5
0
func addpltsym(ctxt *ld.Link, s *ld.Symbol) {
	if s.Plt >= 0 {
		return
	}

	ld.Adddynsym(ctxt, s)

	if ld.Iself {
		plt := ld.Linklookup(ctxt, ".plt", 0)
		got := ld.Linklookup(ctxt, ".got.plt", 0)
		rel := ld.Linklookup(ctxt, ".rel.plt", 0)
		if plt.Size == 0 {
			elfsetupplt(ctxt)
		}

		// .got entry
		s.Got = int32(got.Size)

		// In theory, all GOT should point to the first PLT entry,
		// Linux/ARM's dynamic linker will do that for us, but FreeBSD/ARM's
		// dynamic linker won't, so we'd better do it ourselves.
		ld.Addaddrplus(ctxt, got, plt, 0)

		// .plt entry, this depends on the .got entry
		s.Plt = int32(plt.Size)

		addpltreloc(ctxt, plt, got, s, obj.R_PLT0) // add lr, pc, #0xXX00000
		addpltreloc(ctxt, plt, got, s, obj.R_PLT1) // add lr, lr, #0xYY000
		addpltreloc(ctxt, plt, got, s, obj.R_PLT2) // ldr pc, [lr, #0xZZZ]!

		// rel
		ld.Addaddrplus(ctxt, rel, got, int64(s.Got))

		ld.Adduint32(ctxt, rel, ld.ELF32_R_INFO(uint32(s.Dynid), ld.R_ARM_JUMP_SLOT))
	} else {
		ctxt.Diag("addpltsym: unsupported binary format")
	}
}
Пример #6
0
Файл: asm.go Проект: hurkgu/go
func elfsetupplt(ctxt *ld.Link) {
	plt := ld.Linklookup(ctxt, ".plt", 0)
	got := ld.Linklookup(ctxt, ".got", 0)
	if plt.Size == 0 {
		// stg     %r1,56(%r15)
		ld.Adduint8(ctxt, plt, 0xe3)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0xf0)
		ld.Adduint8(ctxt, plt, 0x38)
		ld.Adduint8(ctxt, plt, 0x00)
		ld.Adduint8(ctxt, plt, 0x24)
		// larl    %r1,_GLOBAL_OFFSET_TABLE_
		ld.Adduint8(ctxt, plt, 0xc0)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Addpcrelplus(ctxt, plt, got, 6)
		// mvc     48(8,%r15),8(%r1)
		ld.Adduint8(ctxt, plt, 0xd2)
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0xf0)
		ld.Adduint8(ctxt, plt, 0x30)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x08)
		// lg      %r1,16(%r1)
		ld.Adduint8(ctxt, plt, 0xe3)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x00)
		ld.Adduint8(ctxt, plt, 0x04)
		// br      %r1
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0xf1)
		// nopr    %r0
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0x00)
		// nopr    %r0
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0x00)
		// nopr    %r0
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0x00)

		// assume got->size == 0 too
		ld.Addaddrplus(ctxt, got, ld.Linklookup(ctxt, ".dynamic", 0), 0)

		ld.Adduint64(ctxt, got, 0)
		ld.Adduint64(ctxt, got, 0)
	}
}
Пример #7
0
func addgotsyminternal(ctxt *ld.Link, s *ld.Symbol) {
	if s.Got >= 0 {
		return
	}

	got := ld.Linklookup(ctxt, ".got", 0)
	s.Got = int32(got.Size)

	ld.Addaddrplus(ctxt, got, s, 0)

	if ld.Iself {
	} else {
		ctxt.Diag("addgotsyminternal: unsupported binary format")
	}
}
Пример #8
0
func addgotsym(ctxt *ld.Link, s *ld.Symbol) {
	if s.Got >= 0 {
		return
	}

	ld.Adddynsym(ctxt, s)
	got := ld.Linklookup(ctxt, ".got", 0)
	s.Got = int32(got.Size)
	ld.Adduint32(ctxt, got, 0)

	if ld.Iself {
		rel := ld.Linklookup(ctxt, ".rel", 0)
		ld.Addaddrplus(ctxt, rel, got, int64(s.Got))
		ld.Adduint32(ctxt, rel, ld.ELF32_R_INFO(uint32(s.Dynid), ld.R_ARM_GLOB_DAT))
	} else {
		ctxt.Diag("addgotsym: unsupported binary format")
	}
}
Пример #9
0
Файл: asm.go Проект: Mokolea/go
func addpltsym(ctxt *ld.Link, s *ld.Symbol) {
	if s.Plt >= 0 {
		return
	}

	ld.Adddynsym(ctxt, s)

	if ld.Iself {
		plt := ld.Linklookup(ctxt, ".plt", 0)
		rela := ld.Linklookup(ctxt, ".rela.plt", 0)
		if plt.Size == 0 {
			elfsetupplt()
		}

		// Create the glink resolver if necessary
		glink := ensureglinkresolver()

		// Write symbol resolver stub (just a branch to the
		// glink resolver stub)
		r := ld.Addrel(glink)

		r.Sym = glink
		r.Off = int32(glink.Size)
		r.Siz = 4
		r.Type = obj.R_CALLPOWER
		ld.Adduint32(ctxt, glink, 0x48000000) // b .glink

		// In the ppc64 ABI, the dynamic linker is responsible
		// for writing the entire PLT.  We just need to
		// reserve 8 bytes for each PLT entry and generate a
		// JMP_SLOT dynamic relocation for it.
		//
		// TODO(austin): ABI v1 is different
		s.Plt = int32(plt.Size)

		plt.Size += 8

		ld.Addaddrplus(ctxt, rela, plt, int64(s.Plt))
		ld.Adduint64(ctxt, rela, ld.ELF64_R_INFO(uint32(s.Dynid), ld.R_PPC64_JMP_SLOT))
		ld.Adduint64(ctxt, rela, 0)
	} else {
		ld.Diag("addpltsym: unsupported binary format")
	}
}
Пример #10
0
Файл: asm.go Проект: Mokolea/go
func addgotsym(s *ld.Symbol) {
	if s.Got >= 0 {
		return
	}

	ld.Adddynsym(ld.Ctxt, s)
	got := ld.Linklookup(ld.Ctxt, ".got", 0)
	s.Got = int32(got.Size)
	ld.Adduint64(ld.Ctxt, got, 0)

	if ld.Iself {
		rela := ld.Linklookup(ld.Ctxt, ".rela", 0)
		ld.Addaddrplus(ld.Ctxt, rela, got, int64(s.Got))
		ld.Adduint64(ld.Ctxt, rela, ld.ELF64_R_INFO(uint32(s.Dynid), ld.R_390_GLOB_DAT))
		ld.Adduint64(ld.Ctxt, rela, 0)
	} else {
		ld.Diag("addgotsym: unsupported binary format")
	}
}
Пример #11
0
Файл: asm.go Проект: achanda/go
func addgotsym(ctxt *ld.Link, s *ld.Symbol) {
	if s.Got >= 0 {
		return
	}

	ld.Adddynsym(ctxt, s)
	got := ctxt.Syms.Lookup(".got", 0)
	s.Got = int32(got.Size)
	ld.Adduint32(ctxt, got, 0)

	if ld.Iself {
		rel := ctxt.Syms.Lookup(".rel", 0)
		ld.Addaddrplus(ctxt, rel, got, int64(s.Got))
		ld.Adduint32(ctxt, rel, ld.ELF32_R_INFO(uint32(s.Dynid), ld.R_386_GLOB_DAT))
	} else if ld.Headtype == obj.Hdarwin {
		ld.Adduint32(ctxt, ctxt.Syms.Lookup(".linkedit.got", 0), uint32(s.Dynid))
	} else {
		ld.Errorf(s, "addgotsym: unsupported binary format")
	}
}
Пример #12
0
func addgotsym(ctxt *ld.Link, s *ld.LSym) {
	if s.Got >= 0 {
		return
	}

	ld.Adddynsym(ctxt, s)
	got := ld.Linklookup(ctxt, ".got", 0)
	s.Got = int32(got.Size)
	ld.Adduint32(ctxt, got, 0)

	if ld.Iself {
		rel := ld.Linklookup(ctxt, ".rel", 0)
		ld.Addaddrplus(ctxt, rel, got, int64(s.Got))
		ld.Adduint32(ctxt, rel, ld.ELF32_R_INFO(uint32(s.Dynid), ld.R_386_GLOB_DAT))
	} else if ld.HEADTYPE == obj.Hdarwin {
		ld.Adduint32(ctxt, ld.Linklookup(ctxt, ".linkedit.got", 0), uint32(s.Dynid))
	} else {
		ld.Diag("addgotsym: unsupported binary format")
	}
}
Пример #13
0
Файл: asm.go Проект: achanda/go
func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) bool {
	targ := r.Sym

	switch r.Type {
	default:
		if r.Type >= 256 {
			ld.Errorf(s, "unexpected relocation type %d", r.Type)
			return false
		}

		// Handle relocations found in ELF object files.
	case 256 + ld.R_X86_64_PC32:
		if targ.Type == obj.SDYNIMPORT {
			ld.Errorf(s, "unexpected R_X86_64_PC32 relocation for dynamic symbol %s", targ.Name)
		}
		if targ.Type == 0 || targ.Type == obj.SXREF {
			ld.Errorf(s, "unknown symbol %s in pcrel", targ.Name)
		}
		r.Type = obj.R_PCREL
		r.Add += 4
		return true

	case 256 + ld.R_X86_64_PLT32:
		r.Type = obj.R_PCREL
		r.Add += 4
		if targ.Type == obj.SDYNIMPORT {
			addpltsym(ctxt, targ)
			r.Sym = ctxt.Syms.Lookup(".plt", 0)
			r.Add += int64(targ.Plt)
		}

		return true

	case 256 + ld.R_X86_64_GOTPCREL, 256 + ld.R_X86_64_GOTPCRELX, 256 + ld.R_X86_64_REX_GOTPCRELX:
		if targ.Type != obj.SDYNIMPORT {
			// have symbol
			if r.Off >= 2 && s.P[r.Off-2] == 0x8b {
				// turn MOVQ of GOT entry into LEAQ of symbol itself
				s.P[r.Off-2] = 0x8d

				r.Type = obj.R_PCREL
				r.Add += 4
				return true
			}
		}

		// fall back to using GOT and hope for the best (CMOV*)
		// TODO: just needs relocation, no need to put in .dynsym
		addgotsym(ctxt, targ)

		r.Type = obj.R_PCREL
		r.Sym = ctxt.Syms.Lookup(".got", 0)
		r.Add += 4
		r.Add += int64(targ.Got)
		return true

	case 256 + ld.R_X86_64_64:
		if targ.Type == obj.SDYNIMPORT {
			ld.Errorf(s, "unexpected R_X86_64_64 relocation for dynamic symbol %s", targ.Name)
		}
		r.Type = obj.R_ADDR
		return true

	// Handle relocations found in Mach-O object files.
	case 512 + ld.MACHO_X86_64_RELOC_UNSIGNED*2 + 0,
		512 + ld.MACHO_X86_64_RELOC_SIGNED*2 + 0,
		512 + ld.MACHO_X86_64_RELOC_BRANCH*2 + 0:
		// TODO: What is the difference between all these?
		r.Type = obj.R_ADDR

		if targ.Type == obj.SDYNIMPORT {
			ld.Errorf(s, "unexpected reloc for dynamic symbol %s", targ.Name)
		}
		return true

	case 512 + ld.MACHO_X86_64_RELOC_BRANCH*2 + 1:
		if targ.Type == obj.SDYNIMPORT {
			addpltsym(ctxt, targ)
			r.Sym = ctxt.Syms.Lookup(".plt", 0)
			r.Add = int64(targ.Plt)
			r.Type = obj.R_PCREL
			return true
		}
		fallthrough

		// fall through
	case 512 + ld.MACHO_X86_64_RELOC_UNSIGNED*2 + 1,
		512 + ld.MACHO_X86_64_RELOC_SIGNED*2 + 1,
		512 + ld.MACHO_X86_64_RELOC_SIGNED_1*2 + 1,
		512 + ld.MACHO_X86_64_RELOC_SIGNED_2*2 + 1,
		512 + ld.MACHO_X86_64_RELOC_SIGNED_4*2 + 1:
		r.Type = obj.R_PCREL

		if targ.Type == obj.SDYNIMPORT {
			ld.Errorf(s, "unexpected pc-relative reloc for dynamic symbol %s", targ.Name)
		}
		return true

	case 512 + ld.MACHO_X86_64_RELOC_GOT_LOAD*2 + 1:
		if targ.Type != obj.SDYNIMPORT {
			// have symbol
			// turn MOVQ of GOT entry into LEAQ of symbol itself
			if r.Off < 2 || s.P[r.Off-2] != 0x8b {
				ld.Errorf(s, "unexpected GOT_LOAD reloc for non-dynamic symbol %s", targ.Name)
				return false
			}

			s.P[r.Off-2] = 0x8d
			r.Type = obj.R_PCREL
			return true
		}
		fallthrough

		// fall through
	case 512 + ld.MACHO_X86_64_RELOC_GOT*2 + 1:
		if targ.Type != obj.SDYNIMPORT {
			ld.Errorf(s, "unexpected GOT reloc for non-dynamic symbol %s", targ.Name)
		}
		addgotsym(ctxt, targ)
		r.Type = obj.R_PCREL
		r.Sym = ctxt.Syms.Lookup(".got", 0)
		r.Add += int64(targ.Got)
		return true
	}

	switch r.Type {
	case obj.R_CALL,
		obj.R_PCREL:
		if targ.Type != obj.SDYNIMPORT {
			// nothing to do, the relocation will be laid out in reloc
			return true
		}
		if ld.Headtype == obj.Hwindows || ld.Headtype == obj.Hwindowsgui {
			// nothing to do, the relocation will be laid out in pereloc1
			return true
		} else {
			// for both ELF and Mach-O
			addpltsym(ctxt, targ)
			r.Sym = ctxt.Syms.Lookup(".plt", 0)
			r.Add = int64(targ.Plt)
			return true
		}

	case obj.R_ADDR:
		if s.Type == obj.STEXT && ld.Iself {
			if ld.Headtype == obj.Hsolaris {
				addpltsym(ctxt, targ)
				r.Sym = ctxt.Syms.Lookup(".plt", 0)
				r.Add += int64(targ.Plt)
				return true
			}
			// The code is asking for the address of an external
			// function. We provide it with the address of the
			// correspondent GOT symbol.
			addgotsym(ctxt, targ)

			r.Sym = ctxt.Syms.Lookup(".got", 0)
			r.Add += int64(targ.Got)
			return true
		}

		// Process dynamic relocations for the data sections.
		if ld.Buildmode == ld.BuildmodePIE && ld.Linkmode == ld.LinkInternal {
			// When internally linking, generate dynamic relocations
			// for all typical R_ADDR relocations. The exception
			// are those R_ADDR that are created as part of generating
			// the dynamic relocations and must be resolved statically.
			//
			// There are three phases relevant to understanding this:
			//
			//	dodata()  // we are here
			//	address() // symbol address assignment
			//	reloc()   // resolution of static R_ADDR relocs
			//
			// At this point symbol addresses have not been
			// assigned yet (as the final size of the .rela section
			// will affect the addresses), and so we cannot write
			// the Elf64_Rela.r_offset now. Instead we delay it
			// until after the 'address' phase of the linker is
			// complete. We do this via Addaddrplus, which creates
			// a new R_ADDR relocation which will be resolved in
			// the 'reloc' phase.
			//
			// These synthetic static R_ADDR relocs must be skipped
			// now, or else we will be caught in an infinite loop
			// of generating synthetic relocs for our synthetic
			// relocs.
			switch s.Name {
			case ".dynsym", ".rela", ".got.plt", ".dynamic":
				return false
			}
		} else {
			// Either internally linking a static executable,
			// in which case we can resolve these relocations
			// statically in the 'reloc' phase, or externally
			// linking, in which case the relocation will be
			// prepared in the 'reloc' phase and passed to the
			// external linker in the 'asmb' phase.
			if s.Type != obj.SDATA && s.Type != obj.SRODATA {
				break
			}
		}

		if ld.Iself {
			// TODO: We generate a R_X86_64_64 relocation for every R_ADDR, even
			// though it would be more efficient (for the dynamic linker) if we
			// generated R_X86_RELATIVE instead.
			ld.Adddynsym(ctxt, targ)
			rela := ctxt.Syms.Lookup(".rela", 0)
			ld.Addaddrplus(ctxt, rela, s, int64(r.Off))
			if r.Siz == 8 {
				ld.Adduint64(ctxt, rela, ld.ELF64_R_INFO(uint32(targ.Dynid), ld.R_X86_64_64))
			} else {
				// TODO: never happens, remove.
				ld.Adduint64(ctxt, rela, ld.ELF64_R_INFO(uint32(targ.Dynid), ld.R_X86_64_32))
			}
			ld.Adduint64(ctxt, rela, uint64(r.Add))
			r.Type = 256 // ignore during relocsym
			return true
		}

		if ld.Headtype == obj.Hdarwin && s.Size == int64(ld.SysArch.PtrSize) && r.Off == 0 {
			// Mach-O relocations are a royal pain to lay out.
			// They use a compact stateful bytecode representation
			// that is too much bother to deal with.
			// Instead, interpret the C declaration
			//	void *_Cvar_stderr = &stderr;
			// as making _Cvar_stderr the name of a GOT entry
			// for stderr. This is separate from the usual GOT entry,
			// just in case the C code assigns to the variable,
			// and of course it only works for single pointers,
			// but we only need to support cgo and that's all it needs.
			ld.Adddynsym(ctxt, targ)

			got := ctxt.Syms.Lookup(".got", 0)
			s.Type = got.Type | obj.SSUB
			s.Outer = got
			s.Sub = got.Sub
			got.Sub = s
			s.Value = got.Size
			ld.Adduint64(ctxt, got, 0)
			ld.Adduint32(ctxt, ctxt.Syms.Lookup(".linkedit.got", 0), uint32(targ.Dynid))
			r.Type = 256 // ignore during relocsym
			return true
		}

		if ld.Headtype == obj.Hwindows || ld.Headtype == obj.Hwindowsgui {
			// nothing to do, the relocation will be laid out in pereloc1
			return true
		}
	}

	return false
}
Пример #14
0
Файл: asm.go Проект: Mokolea/go
func adddynrel(s *ld.Symbol, r *ld.Reloc) {
	targ := r.Sym
	ld.Ctxt.Cursym = s

	switch r.Type {
	default:
		if r.Type >= 256 {
			ld.Diag("unexpected relocation type %d", r.Type)
			return
		}

		// Handle relocations found in ELF object files.
	case 256 + ld.R_PPC64_REL24:
		r.Type = obj.R_CALLPOWER

		// This is a local call, so the caller isn't setting
		// up r12 and r2 is the same for the caller and
		// callee. Hence, we need to go to the local entry
		// point.  (If we don't do this, the callee will try
		// to use r12 to compute r2.)
		r.Add += int64(r.Sym.Localentry) * 4

		if targ.Type == obj.SDYNIMPORT {
			// Should have been handled in elfsetupplt
			ld.Diag("unexpected R_PPC64_REL24 for dyn import")
		}

		return

	case 256 + ld.R_PPC_REL32:
		r.Type = obj.R_PCREL
		r.Add += 4

		if targ.Type == obj.SDYNIMPORT {
			ld.Diag("unexpected R_PPC_REL32 for dyn import")
		}

		return

	case 256 + ld.R_PPC64_ADDR64:
		r.Type = obj.R_ADDR
		if targ.Type == obj.SDYNIMPORT {
			// These happen in .toc sections
			ld.Adddynsym(ld.Ctxt, targ)

			rela := ld.Linklookup(ld.Ctxt, ".rela", 0)
			ld.Addaddrplus(ld.Ctxt, rela, s, int64(r.Off))
			ld.Adduint64(ld.Ctxt, rela, ld.ELF64_R_INFO(uint32(targ.Dynid), ld.R_PPC64_ADDR64))
			ld.Adduint64(ld.Ctxt, rela, uint64(r.Add))
			r.Type = 256 // ignore during relocsym
		}

		return

	case 256 + ld.R_PPC64_TOC16:
		r.Type = obj.R_POWER_TOC
		r.Variant = ld.RV_POWER_LO | ld.RV_CHECK_OVERFLOW
		return

	case 256 + ld.R_PPC64_TOC16_LO:
		r.Type = obj.R_POWER_TOC
		r.Variant = ld.RV_POWER_LO
		return

	case 256 + ld.R_PPC64_TOC16_HA:
		r.Type = obj.R_POWER_TOC
		r.Variant = ld.RV_POWER_HA | ld.RV_CHECK_OVERFLOW
		return

	case 256 + ld.R_PPC64_TOC16_HI:
		r.Type = obj.R_POWER_TOC
		r.Variant = ld.RV_POWER_HI | ld.RV_CHECK_OVERFLOW
		return

	case 256 + ld.R_PPC64_TOC16_DS:
		r.Type = obj.R_POWER_TOC
		r.Variant = ld.RV_POWER_DS | ld.RV_CHECK_OVERFLOW
		return

	case 256 + ld.R_PPC64_TOC16_LO_DS:
		r.Type = obj.R_POWER_TOC
		r.Variant = ld.RV_POWER_DS
		return

	case 256 + ld.R_PPC64_REL16_LO:
		r.Type = obj.R_PCREL
		r.Variant = ld.RV_POWER_LO
		r.Add += 2 // Compensate for relocation size of 2
		return

	case 256 + ld.R_PPC64_REL16_HI:
		r.Type = obj.R_PCREL
		r.Variant = ld.RV_POWER_HI | ld.RV_CHECK_OVERFLOW
		r.Add += 2
		return

	case 256 + ld.R_PPC64_REL16_HA:
		r.Type = obj.R_PCREL
		r.Variant = ld.RV_POWER_HA | ld.RV_CHECK_OVERFLOW
		r.Add += 2
		return
	}

	// Handle references to ELF symbols from our own object files.
	if targ.Type != obj.SDYNIMPORT {
		return
	}

	// TODO(austin): Translate our relocations to ELF

	ld.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ.Name, r.Type, targ.Type)
}
Пример #15
0
func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
	targ := r.Sym
	ctxt.Cursym = s

	switch r.Type {
	default:
		if r.Type >= 256 {
			ctxt.Diag("unexpected relocation type %d", r.Type)
			return
		}

		// Handle relocations found in ELF object files.
	case 256 + ld.R_ARM_PLT32:
		r.Type = obj.R_CALLARM

		if targ.Type == obj.SDYNIMPORT {
			addpltsym(ctxt, targ)
			r.Sym = ld.Linklookup(ctxt, ".plt", 0)
			r.Add = int64(braddoff(int32(r.Add), targ.Plt/4))
		}

		return

	case 256 + ld.R_ARM_THM_PC22: // R_ARM_THM_CALL
		ld.Exitf("R_ARM_THM_CALL, are you using -marm?")
		return

	case 256 + ld.R_ARM_GOT32: // R_ARM_GOT_BREL
		if targ.Type != obj.SDYNIMPORT {
			addgotsyminternal(ctxt, targ)
		} else {
			addgotsym(ctxt, targ)
		}

		r.Type = obj.R_CONST // write r->add during relocsym
		r.Sym = nil
		r.Add += int64(targ.Got)
		return

	case 256 + ld.R_ARM_GOT_PREL: // GOT(nil) + A - nil
		if targ.Type != obj.SDYNIMPORT {
			addgotsyminternal(ctxt, targ)
		} else {
			addgotsym(ctxt, targ)
		}

		r.Type = obj.R_PCREL
		r.Sym = ld.Linklookup(ctxt, ".got", 0)
		r.Add += int64(targ.Got) + 4
		return

	case 256 + ld.R_ARM_GOTOFF: // R_ARM_GOTOFF32
		r.Type = obj.R_GOTOFF

		return

	case 256 + ld.R_ARM_GOTPC: // R_ARM_BASE_PREL
		r.Type = obj.R_PCREL

		r.Sym = ld.Linklookup(ctxt, ".got", 0)
		r.Add += 4
		return

	case 256 + ld.R_ARM_CALL:
		r.Type = obj.R_CALLARM
		if targ.Type == obj.SDYNIMPORT {
			addpltsym(ctxt, targ)
			r.Sym = ld.Linklookup(ctxt, ".plt", 0)
			r.Add = int64(braddoff(int32(r.Add), targ.Plt/4))
		}

		return

	case 256 + ld.R_ARM_REL32: // R_ARM_REL32
		r.Type = obj.R_PCREL

		r.Add += 4
		return

	case 256 + ld.R_ARM_ABS32:
		if targ.Type == obj.SDYNIMPORT {
			ctxt.Diag("unexpected R_ARM_ABS32 relocation for dynamic symbol %s", targ.Name)
		}
		r.Type = obj.R_ADDR
		return

		// we can just ignore this, because we are targeting ARM V5+ anyway
	case 256 + ld.R_ARM_V4BX:
		if r.Sym != nil {
			// R_ARM_V4BX is ABS relocation, so this symbol is a dummy symbol, ignore it
			r.Sym.Type = 0
		}

		r.Sym = nil
		return

	case 256 + ld.R_ARM_PC24,
		256 + ld.R_ARM_JUMP24:
		r.Type = obj.R_CALLARM
		if targ.Type == obj.SDYNIMPORT {
			addpltsym(ctxt, targ)
			r.Sym = ld.Linklookup(ctxt, ".plt", 0)
			r.Add = int64(braddoff(int32(r.Add), targ.Plt/4))
		}

		return
	}

	// Handle references to ELF symbols from our own object files.
	if targ.Type != obj.SDYNIMPORT {
		return
	}

	switch r.Type {
	case obj.R_CALLARM:
		addpltsym(ctxt, targ)
		r.Sym = ld.Linklookup(ctxt, ".plt", 0)
		r.Add = int64(targ.Plt)
		return

	case obj.R_ADDR:
		if s.Type != obj.SDATA {
			break
		}
		if ld.Iself {
			ld.Adddynsym(ctxt, targ)
			rel := ld.Linklookup(ctxt, ".rel", 0)
			ld.Addaddrplus(ctxt, rel, s, int64(r.Off))
			ld.Adduint32(ctxt, rel, ld.ELF32_R_INFO(uint32(targ.Dynid), ld.R_ARM_GLOB_DAT)) // we need a nil + A dynamic reloc
			r.Type = obj.R_CONST                                                            // write r->add during relocsym
			r.Sym = nil
			return
		}
	}

	ctxt.Cursym = s
	ctxt.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ.Name, r.Type, targ.Type)
}
Пример #16
0
Файл: asm.go Проект: sreis/go
func adddynrel(s *ld.LSym, r *ld.Reloc) {
	targ := r.Sym
	ld.Ctxt.Cursym = s

	switch r.Type {
	default:
		if r.Type >= 256 {
			ld.Diag("unexpected relocation type %d", r.Type)
			return
		}

		// Handle relocations found in ELF object files.
	case 256 + ld.R_X86_64_PC32:
		if targ.Type == obj.SDYNIMPORT {
			ld.Diag("unexpected R_X86_64_PC32 relocation for dynamic symbol %s", targ.Name)
		}
		if targ.Type == 0 || targ.Type == obj.SXREF {
			ld.Diag("unknown symbol %s in pcrel", targ.Name)
		}
		r.Type = obj.R_PCREL
		r.Add += 4
		return

	case 256 + ld.R_X86_64_PLT32:
		r.Type = obj.R_PCREL
		r.Add += 4
		if targ.Type == obj.SDYNIMPORT {
			addpltsym(targ)
			r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
			r.Add += int64(targ.Plt)
		}

		return

	case 256 + ld.R_X86_64_GOTPCREL, 256 + ld.R_X86_64_GOTPCRELX, 256 + ld.R_X86_64_REX_GOTPCRELX:
		if targ.Type != obj.SDYNIMPORT {
			// have symbol
			if r.Off >= 2 && s.P[r.Off-2] == 0x8b {
				// turn MOVQ of GOT entry into LEAQ of symbol itself
				s.P[r.Off-2] = 0x8d

				r.Type = obj.R_PCREL
				r.Add += 4
				return
			}
		}

		// fall back to using GOT and hope for the best (CMOV*)
		// TODO: just needs relocation, no need to put in .dynsym
		addgotsym(targ)

		r.Type = obj.R_PCREL
		r.Sym = ld.Linklookup(ld.Ctxt, ".got", 0)
		r.Add += 4
		r.Add += int64(targ.Got)
		return

	case 256 + ld.R_X86_64_64:
		if targ.Type == obj.SDYNIMPORT {
			ld.Diag("unexpected R_X86_64_64 relocation for dynamic symbol %s", targ.Name)
		}
		r.Type = obj.R_ADDR
		return

	// Handle relocations found in Mach-O object files.
	case 512 + ld.MACHO_X86_64_RELOC_UNSIGNED*2 + 0,
		512 + ld.MACHO_X86_64_RELOC_SIGNED*2 + 0,
		512 + ld.MACHO_X86_64_RELOC_BRANCH*2 + 0:
		// TODO: What is the difference between all these?
		r.Type = obj.R_ADDR

		if targ.Type == obj.SDYNIMPORT {
			ld.Diag("unexpected reloc for dynamic symbol %s", targ.Name)
		}
		return

	case 512 + ld.MACHO_X86_64_RELOC_BRANCH*2 + 1:
		if targ.Type == obj.SDYNIMPORT {
			addpltsym(targ)
			r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
			r.Add = int64(targ.Plt)
			r.Type = obj.R_PCREL
			return
		}
		fallthrough

		// fall through
	case 512 + ld.MACHO_X86_64_RELOC_UNSIGNED*2 + 1,
		512 + ld.MACHO_X86_64_RELOC_SIGNED*2 + 1,
		512 + ld.MACHO_X86_64_RELOC_SIGNED_1*2 + 1,
		512 + ld.MACHO_X86_64_RELOC_SIGNED_2*2 + 1,
		512 + ld.MACHO_X86_64_RELOC_SIGNED_4*2 + 1:
		r.Type = obj.R_PCREL

		if targ.Type == obj.SDYNIMPORT {
			ld.Diag("unexpected pc-relative reloc for dynamic symbol %s", targ.Name)
		}
		return

	case 512 + ld.MACHO_X86_64_RELOC_GOT_LOAD*2 + 1:
		if targ.Type != obj.SDYNIMPORT {
			// have symbol
			// turn MOVQ of GOT entry into LEAQ of symbol itself
			if r.Off < 2 || s.P[r.Off-2] != 0x8b {
				ld.Diag("unexpected GOT_LOAD reloc for non-dynamic symbol %s", targ.Name)
				return
			}

			s.P[r.Off-2] = 0x8d
			r.Type = obj.R_PCREL
			return
		}
		fallthrough

		// fall through
	case 512 + ld.MACHO_X86_64_RELOC_GOT*2 + 1:
		if targ.Type != obj.SDYNIMPORT {
			ld.Diag("unexpected GOT reloc for non-dynamic symbol %s", targ.Name)
		}
		addgotsym(targ)
		r.Type = obj.R_PCREL
		r.Sym = ld.Linklookup(ld.Ctxt, ".got", 0)
		r.Add += int64(targ.Got)
		return
	}

	// Handle references to ELF symbols from our own object files.
	if targ.Type != obj.SDYNIMPORT {
		return
	}

	switch r.Type {
	case obj.R_CALL,
		obj.R_PCREL:
		if ld.HEADTYPE == obj.Hwindows {
			// nothing to do, the relocation will be laid out in pereloc1
			return
		} else {
			// for both ELF and Mach-O
			addpltsym(targ)
			r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
			r.Add = int64(targ.Plt)
			return
		}

	case obj.R_ADDR:
		if s.Type == obj.STEXT && ld.Iself {
			if ld.HEADTYPE == obj.Hsolaris {
				addpltsym(targ)
				r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
				r.Add += int64(targ.Plt)
				return
			}
			// The code is asking for the address of an external
			// function. We provide it with the address of the
			// correspondent GOT symbol.
			addgotsym(targ)

			r.Sym = ld.Linklookup(ld.Ctxt, ".got", 0)
			r.Add += int64(targ.Got)
			return
		}

		if s.Type != obj.SDATA {
			break
		}
		if ld.Iself {
			ld.Adddynsym(ld.Ctxt, targ)
			rela := ld.Linklookup(ld.Ctxt, ".rela", 0)
			ld.Addaddrplus(ld.Ctxt, rela, s, int64(r.Off))
			if r.Siz == 8 {
				ld.Adduint64(ld.Ctxt, rela, ld.ELF64_R_INFO(uint32(targ.Dynid), ld.R_X86_64_64))
			} else {
				ld.Adduint64(ld.Ctxt, rela, ld.ELF64_R_INFO(uint32(targ.Dynid), ld.R_X86_64_32))
			}
			ld.Adduint64(ld.Ctxt, rela, uint64(r.Add))
			r.Type = 256 // ignore during relocsym
			return
		}

		if ld.HEADTYPE == obj.Hdarwin && s.Size == int64(ld.Thearch.Ptrsize) && r.Off == 0 {
			// Mach-O relocations are a royal pain to lay out.
			// They use a compact stateful bytecode representation
			// that is too much bother to deal with.
			// Instead, interpret the C declaration
			//	void *_Cvar_stderr = &stderr;
			// as making _Cvar_stderr the name of a GOT entry
			// for stderr. This is separate from the usual GOT entry,
			// just in case the C code assigns to the variable,
			// and of course it only works for single pointers,
			// but we only need to support cgo and that's all it needs.
			ld.Adddynsym(ld.Ctxt, targ)

			got := ld.Linklookup(ld.Ctxt, ".got", 0)
			s.Type = got.Type | obj.SSUB
			s.Outer = got
			s.Sub = got.Sub
			got.Sub = s
			s.Value = got.Size
			ld.Adduint64(ld.Ctxt, got, 0)
			ld.Adduint32(ld.Ctxt, ld.Linklookup(ld.Ctxt, ".linkedit.got", 0), uint32(targ.Dynid))
			r.Type = 256 // ignore during relocsym
			return
		}

		if ld.HEADTYPE == obj.Hwindows {
			// nothing to do, the relocation will be laid out in pereloc1
			return
		}
	}

	ld.Ctxt.Cursym = s
	ld.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ.Name, r.Type, targ.Type)
}
Пример #17
0
Файл: asm.go Проект: sreis/go
func adddynrela(rela *ld.LSym, s *ld.LSym, r *ld.Reloc) {
	ld.Addaddrplus(ld.Ctxt, rela, s, int64(r.Off))
	ld.Adduint64(ld.Ctxt, rela, ld.R_X86_64_RELATIVE)
	ld.Addaddrplus(ld.Ctxt, rela, r.Sym, r.Add) // Addend
}
Пример #18
0
func adddynrela(rel *ld.LSym, s *ld.LSym, r *ld.Reloc) {
	ld.Addaddrplus(ld.Ctxt, rel, s, int64(r.Off))
	ld.Adduint32(ld.Ctxt, rel, ld.R_ARM_RELATIVE)
}
Пример #19
0
Файл: asm.go Проект: hurkgu/go
func addpltsym(ctxt *ld.Link, s *ld.Symbol) {
	if s.Plt >= 0 {
		return
	}

	ld.Adddynsym(ctxt, s)

	if ld.Iself {
		plt := ld.Linklookup(ctxt, ".plt", 0)
		got := ld.Linklookup(ctxt, ".got", 0)
		rela := ld.Linklookup(ctxt, ".rela.plt", 0)
		if plt.Size == 0 {
			elfsetupplt(ctxt)
		}
		// larl    %r1,_GLOBAL_OFFSET_TABLE_+index

		ld.Adduint8(ctxt, plt, 0xc0)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Addpcrelplus(ctxt, plt, got, got.Size+6) // need variant?

		// add to got: pointer to current pos in plt
		ld.Addaddrplus(ctxt, got, plt, plt.Size+8) // weird but correct
		// lg      %r1,0(%r1)
		ld.Adduint8(ctxt, plt, 0xe3)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x00)
		ld.Adduint8(ctxt, plt, 0x00)
		ld.Adduint8(ctxt, plt, 0x04)
		// br      %r1
		ld.Adduint8(ctxt, plt, 0x07)
		ld.Adduint8(ctxt, plt, 0xf1)
		// basr    %r1,%r0
		ld.Adduint8(ctxt, plt, 0x0d)
		ld.Adduint8(ctxt, plt, 0x10)
		// lgf     %r1,12(%r1)
		ld.Adduint8(ctxt, plt, 0xe3)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x10)
		ld.Adduint8(ctxt, plt, 0x0c)
		ld.Adduint8(ctxt, plt, 0x00)
		ld.Adduint8(ctxt, plt, 0x14)
		// jg .plt
		ld.Adduint8(ctxt, plt, 0xc0)
		ld.Adduint8(ctxt, plt, 0xf4)

		ld.Adduint32(ctxt, plt, uint32(-((plt.Size - 2) >> 1))) // roll-your-own relocation
		//.plt index
		ld.Adduint32(ctxt, plt, uint32(rela.Size)) // rela size before current entry

		// rela
		ld.Addaddrplus(ctxt, rela, got, got.Size-8)

		ld.Adduint64(ctxt, rela, ld.ELF64_R_INFO(uint32(s.Dynid), ld.R_390_JMP_SLOT))
		ld.Adduint64(ctxt, rela, 0)

		s.Plt = int32(plt.Size - 32)

	} else {
		ctxt.Diag("addpltsym: unsupported binary format")
	}
}
Пример #20
0
func adddynrel(s *ld.LSym, r *ld.Reloc) {
	targ := r.Sym
	ld.Ctxt.Cursym = s

	switch r.Type {
	default:
		if r.Type >= 256 {
			ld.Diag("unexpected relocation type %d", r.Type)
			return
		}

		// Handle relocations found in ELF object files.
	case 256 + ld.R_386_PC32:
		if targ.Type == obj.SDYNIMPORT {
			ld.Diag("unexpected R_386_PC32 relocation for dynamic symbol %s", targ.Name)
		}
		if targ.Type == 0 || targ.Type == obj.SXREF {
			ld.Diag("unknown symbol %s in pcrel", targ.Name)
		}
		r.Type = obj.R_PCREL
		r.Add += 4
		return

	case 256 + ld.R_386_PLT32:
		r.Type = obj.R_PCREL
		r.Add += 4
		if targ.Type == obj.SDYNIMPORT {
			addpltsym(ld.Ctxt, targ)
			r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
			r.Add += int64(targ.Plt)
		}

		return

	case 256 + ld.R_386_GOT32, 256 + ld.R_386_GOT32X:
		if targ.Type != obj.SDYNIMPORT {
			// have symbol
			if r.Off >= 2 && s.P[r.Off-2] == 0x8b {
				// turn MOVL of GOT entry into LEAL of symbol address, relative to GOT.
				s.P[r.Off-2] = 0x8d

				r.Type = obj.R_GOTOFF
				return
			}

			if r.Off >= 2 && s.P[r.Off-2] == 0xff && s.P[r.Off-1] == 0xb3 {
				// turn PUSHL of GOT entry into PUSHL of symbol itself.
				// use unnecessary SS prefix to keep instruction same length.
				s.P[r.Off-2] = 0x36

				s.P[r.Off-1] = 0x68
				r.Type = obj.R_ADDR
				return
			}

			ld.Diag("unexpected GOT reloc for non-dynamic symbol %s", targ.Name)
			return
		}

		addgotsym(ld.Ctxt, targ)
		r.Type = obj.R_CONST // write r->add during relocsym
		r.Sym = nil
		r.Add += int64(targ.Got)
		return

	case 256 + ld.R_386_GOTOFF:
		r.Type = obj.R_GOTOFF
		return

	case 256 + ld.R_386_GOTPC:
		r.Type = obj.R_PCREL
		r.Sym = ld.Linklookup(ld.Ctxt, ".got", 0)
		r.Add += 4
		return

	case 256 + ld.R_386_32:
		if targ.Type == obj.SDYNIMPORT {
			ld.Diag("unexpected R_386_32 relocation for dynamic symbol %s", targ.Name)
		}
		r.Type = obj.R_ADDR
		return

	case 512 + ld.MACHO_GENERIC_RELOC_VANILLA*2 + 0:
		r.Type = obj.R_ADDR
		if targ.Type == obj.SDYNIMPORT {
			ld.Diag("unexpected reloc for dynamic symbol %s", targ.Name)
		}
		return

	case 512 + ld.MACHO_GENERIC_RELOC_VANILLA*2 + 1:
		if targ.Type == obj.SDYNIMPORT {
			addpltsym(ld.Ctxt, targ)
			r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
			r.Add = int64(targ.Plt)
			r.Type = obj.R_PCREL
			return
		}

		r.Type = obj.R_PCREL
		return

	case 512 + ld.MACHO_FAKE_GOTPCREL:
		if targ.Type != obj.SDYNIMPORT {
			// have symbol
			// turn MOVL of GOT entry into LEAL of symbol itself
			if r.Off < 2 || s.P[r.Off-2] != 0x8b {
				ld.Diag("unexpected GOT reloc for non-dynamic symbol %s", targ.Name)
				return
			}

			s.P[r.Off-2] = 0x8d
			r.Type = obj.R_PCREL
			return
		}

		addgotsym(ld.Ctxt, targ)
		r.Sym = ld.Linklookup(ld.Ctxt, ".got", 0)
		r.Add += int64(targ.Got)
		r.Type = obj.R_PCREL
		return
	}

	// Handle references to ELF symbols from our own object files.
	if targ.Type != obj.SDYNIMPORT {
		return
	}

	switch r.Type {
	case obj.R_CALL,
		obj.R_PCREL:
		addpltsym(ld.Ctxt, targ)
		r.Sym = ld.Linklookup(ld.Ctxt, ".plt", 0)
		r.Add = int64(targ.Plt)
		return

	case obj.R_ADDR:
		if s.Type != obj.SDATA {
			break
		}
		if ld.Iself {
			ld.Adddynsym(ld.Ctxt, targ)
			rel := ld.Linklookup(ld.Ctxt, ".rel", 0)
			ld.Addaddrplus(ld.Ctxt, rel, s, int64(r.Off))
			ld.Adduint32(ld.Ctxt, rel, ld.ELF32_R_INFO(uint32(targ.Dynid), ld.R_386_32))
			r.Type = obj.R_CONST // write r->add during relocsym
			r.Sym = nil
			return
		}

		if ld.HEADTYPE == obj.Hdarwin && s.Size == PtrSize && r.Off == 0 {
			// Mach-O relocations are a royal pain to lay out.
			// They use a compact stateful bytecode representation
			// that is too much bother to deal with.
			// Instead, interpret the C declaration
			//	void *_Cvar_stderr = &stderr;
			// as making _Cvar_stderr the name of a GOT entry
			// for stderr.  This is separate from the usual GOT entry,
			// just in case the C code assigns to the variable,
			// and of course it only works for single pointers,
			// but we only need to support cgo and that's all it needs.
			ld.Adddynsym(ld.Ctxt, targ)

			got := ld.Linklookup(ld.Ctxt, ".got", 0)
			s.Type = got.Type | obj.SSUB
			s.Outer = got
			s.Sub = got.Sub
			got.Sub = s
			s.Value = got.Size
			ld.Adduint32(ld.Ctxt, got, 0)
			ld.Adduint32(ld.Ctxt, ld.Linklookup(ld.Ctxt, ".linkedit.got", 0), uint32(targ.Dynid))
			r.Type = 256 // ignore during relocsym
			return
		}

		if ld.HEADTYPE == obj.Hwindows && s.Size == PtrSize {
			// nothing to do, the relocation will be laid out in pereloc1
			return
		}
	}

	ld.Ctxt.Cursym = s
	ld.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ.Name, r.Type, targ.Type)
}
Пример #21
0
Файл: asm.go Проект: sreis/go
func addpltsym(s *ld.LSym) {
	if s.Plt >= 0 {
		return
	}

	ld.Adddynsym(ld.Ctxt, s)

	if ld.Iself {
		plt := ld.Linklookup(ld.Ctxt, ".plt", 0)
		got := ld.Linklookup(ld.Ctxt, ".got.plt", 0)
		rela := ld.Linklookup(ld.Ctxt, ".rela.plt", 0)
		if plt.Size == 0 {
			elfsetupplt()
		}

		// jmpq *got+size(IP)
		ld.Adduint8(ld.Ctxt, plt, 0xff)

		ld.Adduint8(ld.Ctxt, plt, 0x25)
		ld.Addpcrelplus(ld.Ctxt, plt, got, got.Size)

		// add to got: pointer to current pos in plt
		ld.Addaddrplus(ld.Ctxt, got, plt, plt.Size)

		// pushq $x
		ld.Adduint8(ld.Ctxt, plt, 0x68)

		ld.Adduint32(ld.Ctxt, plt, uint32((got.Size-24-8)/8))

		// jmpq .plt
		ld.Adduint8(ld.Ctxt, plt, 0xe9)

		ld.Adduint32(ld.Ctxt, plt, uint32(-(plt.Size + 4)))

		// rela
		ld.Addaddrplus(ld.Ctxt, rela, got, got.Size-8)

		ld.Adduint64(ld.Ctxt, rela, ld.ELF64_R_INFO(uint32(s.Dynid), ld.R_X86_64_JMP_SLOT))
		ld.Adduint64(ld.Ctxt, rela, 0)

		s.Plt = int32(plt.Size - 16)
	} else if ld.HEADTYPE == obj.Hdarwin {
		// To do lazy symbol lookup right, we're supposed
		// to tell the dynamic loader which library each
		// symbol comes from and format the link info
		// section just so. I'm too lazy (ha!) to do that
		// so for now we'll just use non-lazy pointers,
		// which don't need to be told which library to use.
		//
		// http://networkpx.blogspot.com/2009/09/about-lcdyldinfoonly-command.html
		// has details about what we're avoiding.

		addgotsym(s)
		plt := ld.Linklookup(ld.Ctxt, ".plt", 0)

		ld.Adduint32(ld.Ctxt, ld.Linklookup(ld.Ctxt, ".linkedit.plt", 0), uint32(s.Dynid))

		// jmpq *got+size(IP)
		s.Plt = int32(plt.Size)

		ld.Adduint8(ld.Ctxt, plt, 0xff)
		ld.Adduint8(ld.Ctxt, plt, 0x25)
		ld.Addpcrelplus(ld.Ctxt, plt, ld.Linklookup(ld.Ctxt, ".got", 0), int64(s.Got))
	} else {
		ld.Diag("addpltsym: unsupported binary format")
	}
}