cmd/link: generate dynamic relocs for internal PIE

This reuses the machinery built for dynamic loading of shared
libraries. The significant difference with PIE is we generate
dynamic relocations for known internal symbols, not just
dynamic external symbols.

Part of adding PIE internal linking on linux/amd64.

Change-Id: I4afa24070bfb61f94f8d3648f2433d5343bac3fe
Reviewed-on: https://go-review.googlesource.com/28539Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/link/internal/amd64/asm.go

@@ -93,7 +93,7 @@ func gentext(ctxt *ld.Link) {
 	ld.Addaddr(ctxt, initarray_entry, initfunc)
 }
 
-func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
+func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) bool {
 	targ := r.Sym
 	ctxt.Cursym = s
 
@@ -101,7 +101,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 	default:
 		if r.Type >= 256 {
 			ctxt.Diag("unexpected relocation type %d", r.Type)
-			return
+			return false
 		}
 
 		// Handle relocations found in ELF object files.
@@ -114,7 +114,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		}
 		r.Type = obj.R_PCREL
 		r.Add += 4
-		return
+		return true
 
 	case 256 + ld.R_X86_64_PLT32:
 		r.Type = obj.R_PCREL
@@ -125,7 +125,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			r.Add += int64(targ.Plt)
 		}
 
-		return
+		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 {
@@ -136,7 +136,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 
 				r.Type = obj.R_PCREL
 				r.Add += 4
-				return
+				return true
 			}
 		}
 
@@ -148,14 +148,14 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		r.Sym = ld.Linklookup(ctxt, ".got", 0)
 		r.Add += 4
 		r.Add += int64(targ.Got)
-		return
+		return true
 
 	case 256 + ld.R_X86_64_64:
 		if targ.Type == obj.SDYNIMPORT {
 			ctxt.Diag("unexpected R_X86_64_64 relocation for dynamic symbol %s", targ.Name)
 		}
 		r.Type = obj.R_ADDR
-		return
+		return true
 
 	// Handle relocations found in Mach-O object files.
 	case 512 + ld.MACHO_X86_64_RELOC_UNSIGNED*2 + 0,
@@ -167,7 +167,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		if targ.Type == obj.SDYNIMPORT {
 			ctxt.Diag("unexpected reloc for dynamic symbol %s", targ.Name)
 		}
-		return
+		return true
 
 	case 512 + ld.MACHO_X86_64_RELOC_BRANCH*2 + 1:
 		if targ.Type == obj.SDYNIMPORT {
@@ -175,7 +175,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			r.Sym = ld.Linklookup(ctxt, ".plt", 0)
 			r.Add = int64(targ.Plt)
 			r.Type = obj.R_PCREL
-			return
+			return true
 		}
 		fallthrough
 
@@ -190,7 +190,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		if targ.Type == obj.SDYNIMPORT {
 			ctxt.Diag("unexpected pc-relative reloc for dynamic symbol %s", targ.Name)
 		}
-		return
+		return true
 
 	case 512 + ld.MACHO_X86_64_RELOC_GOT_LOAD*2 + 1:
 		if targ.Type != obj.SDYNIMPORT {
@@ -198,12 +198,12 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			// turn MOVQ of GOT entry into LEAQ of symbol itself
 			if r.Off < 2 || s.P[r.Off-2] != 0x8b {
 				ctxt.Diag("unexpected GOT_LOAD reloc for non-dynamic symbol %s", targ.Name)
-				return
+				return false
 			}
 
 			s.P[r.Off-2] = 0x8d
 			r.Type = obj.R_PCREL
-			return
+			return true
 		}
 		fallthrough
 
@@ -216,26 +216,25 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		r.Type = obj.R_PCREL
 		r.Sym = ld.Linklookup(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
+		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
+			return true
 		} else {
 			// for both ELF and Mach-O
 			addpltsym(ctxt, targ)
 			r.Sym = ld.Linklookup(ctxt, ".plt", 0)
 			r.Add = int64(targ.Plt)
-			return
+			return true
 		}
 
 	case obj.R_ADDR:
@@ -244,7 +243,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 				addpltsym(ctxt, targ)
 				r.Sym = ld.Linklookup(ctxt, ".plt", 0)
 				r.Add += int64(targ.Plt)
-				return
+				return true
 			}
 			// The code is asking for the address of an external
 			// function. We provide it with the address of the
@@ -253,10 +252,10 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 
 			r.Sym = ld.Linklookup(ctxt, ".got", 0)
 			r.Add += int64(targ.Got)
-			return
+			return true
 		}
 
-		if s.Type != obj.SDATA {
+		if s.Type != obj.SDATA && s.Type != obj.SRODATA {
 			break
 		}
 		if ld.Iself {
@@ -270,7 +269,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			}
 			ld.Adduint64(ctxt, rela, uint64(r.Add))
 			r.Type = 256 // ignore during relocsym
-			return
+			return true
 		}
 
 		if ld.Headtype == obj.Hdarwin && s.Size == int64(ld.SysArch.PtrSize) && r.Off == 0 {
@@ -295,17 +294,16 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			ld.Adduint64(ctxt, got, 0)
 			ld.Adduint32(ctxt, ld.Linklookup(ctxt, ".linkedit.got", 0), uint32(targ.Dynid))
 			r.Type = 256 // ignore during relocsym
-			return
+			return true
 		}
 
 		if ld.Headtype == obj.Hwindows || ld.Headtype == obj.Hwindowsgui {
 			// nothing to do, the relocation will be laid out in pereloc1
-			return
+			return true
 		}
 	}
 
-	ctxt.Cursym = s
-	ctxt.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ.Name, r.Type, targ.Type)
+	return false
 }
 
 func elfreloc1(ctxt *ld.Link, r *ld.Reloc, sectoff int64) int {

src/cmd/link/internal/arm/asm.go

@@ -109,7 +109,7 @@ func braddoff(a int32, b int32) int32 {
 	return int32((uint32(a))&0xff000000 | 0x00ffffff&uint32(a+b))
 }
 
-func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
+func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) bool {
 	targ := r.Sym
 	ctxt.Cursym = s
 
@@ -117,7 +117,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 	default:
 		if r.Type >= 256 {
 			ctxt.Diag("unexpected relocation type %d", r.Type)
-			return
+			return false
 		}
 
 		// Handle relocations found in ELF object files.
@@ -130,11 +130,11 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			r.Add = int64(braddoff(int32(r.Add), targ.Plt/4))
 		}
 
-		return
+		return true
 
 	case 256 + ld.R_ARM_THM_PC22: // R_ARM_THM_CALL
 		ld.Exitf("R_ARM_THM_CALL, are you using -marm?")
-		return
+		return false
 
 	case 256 + ld.R_ARM_GOT32: // R_ARM_GOT_BREL
 		if targ.Type != obj.SDYNIMPORT {
@@ -146,7 +146,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		r.Type = obj.R_CONST // write r->add during relocsym
 		r.Sym = nil
 		r.Add += int64(targ.Got)
-		return
+		return true
 
 	case 256 + ld.R_ARM_GOT_PREL: // GOT(nil) + A - nil
 		if targ.Type != obj.SDYNIMPORT {
@@ -158,19 +158,19 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		r.Type = obj.R_PCREL
 		r.Sym = ld.Linklookup(ctxt, ".got", 0)
 		r.Add += int64(targ.Got) + 4
-		return
+		return true
 
 	case 256 + ld.R_ARM_GOTOFF: // R_ARM_GOTOFF32
 		r.Type = obj.R_GOTOFF
 
-		return
+		return true
 
 	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
+		return true
 
 	case 256 + ld.R_ARM_CALL:
 		r.Type = obj.R_CALLARM
@@ -180,20 +180,20 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			r.Add = int64(braddoff(int32(r.Add), targ.Plt/4))
 		}
 
-		return
+		return true
 
 	case 256 + ld.R_ARM_REL32: // R_ARM_REL32
 		r.Type = obj.R_PCREL
 
 		r.Add += 4
-		return
+		return true
 
 	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
+		return true
 
 		// we can just ignore this, because we are targeting ARM V5+ anyway
 	case 256 + ld.R_ARM_V4BX:
@@ -203,7 +203,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		}
 
 		r.Sym = nil
-		return
+		return true
 
 	case 256 + ld.R_ARM_PC24,
 		256 + ld.R_ARM_JUMP24:
@@ -214,12 +214,12 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			r.Add = int64(braddoff(int32(r.Add), targ.Plt/4))
 		}
 
-		return
+		return true
 	}
 
 	// Handle references to ELF symbols from our own object files.
 	if targ.Type != obj.SDYNIMPORT {
-		return
+		return true
 	}
 
 	switch r.Type {
@@ -227,7 +227,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		addpltsym(ctxt, targ)
 		r.Sym = ld.Linklookup(ctxt, ".plt", 0)
 		r.Add = int64(targ.Plt)
-		return
+		return true
 
 	case obj.R_ADDR:
 		if s.Type != obj.SDATA {
@@ -240,12 +240,11 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			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
+			return true
 		}
 	}
 
-	ctxt.Cursym = s
-	ctxt.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ.Name, r.Type, targ.Type)
+	return false
 }
 
 func elfreloc1(ctxt *ld.Link, r *ld.Reloc, sectoff int64) int {

src/cmd/link/internal/arm64/asm.go

@@ -86,8 +86,9 @@ func gentext(ctxt *ld.Link) {
 	ld.Addaddr(ctxt, initarray_entry, initfunc)
 }
 
-func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
+func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) bool {
 	log.Fatalf("adddynrel not implemented")
+	return false
 }
 
 func elfreloc1(ctxt *ld.Link, r *ld.Reloc, sectoff int64) int {

src/cmd/link/internal/ld/data.go

@@ -701,11 +701,21 @@ func dynrelocsym(ctxt *Link, s *Symbol) {
 
 	for ri := 0; ri < len(s.R); ri++ {
 		r := &s.R[ri]
+		if Buildmode == BuildmodePIE && Linkmode == LinkInternal {
+			// It's expected that some relocations will be done
+			// later by relocsym (R_TLS_LE, R_ADDROFF), so
+			// don't worry if Adddynrel returns false.
+			Thearch.Adddynrel(ctxt, s, r)
+			continue
+		}
 		if r.Sym != nil && r.Sym.Type == obj.SDYNIMPORT || r.Type >= 256 {
 			if r.Sym != nil && !r.Sym.Attr.Reachable() {
 				ctxt.Diag("internal inconsistency: dynamic symbol %s is not reachable.", r.Sym.Name)
 			}
-			Thearch.Adddynrel(ctxt, s, r)
+			if !Thearch.Adddynrel(ctxt, s, r) {
+				ctxt.Cursym = s
+				ctxt.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", r.Sym.Name, r.Type, r.Sym.Type)
+			}
 		}
 	}
 }

src/cmd/link/internal/ld/lib.go

@@ -95,7 +95,7 @@ type Arch struct {
 	Openbsddynld     string
 	Dragonflydynld   string
 	Solarisdynld     string
-	Adddynrel        func(*Link, *Symbol, *Reloc)
+	Adddynrel        func(*Link, *Symbol, *Reloc) bool
 	Archinit         func(*Link)
 	Archreloc        func(*Link, *Reloc, *Symbol, *int64) int
 	Archrelocvariant func(*Link, *Reloc, *Symbol, int64) int64

src/cmd/link/internal/mips64/asm.go

@@ -40,8 +40,9 @@ import (
 
 func gentext(ctxt *ld.Link) {}
 
-func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
+func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) bool {
 	log.Fatalf("adddynrel not implemented")
+	return false
 }
 
 func elfreloc1(ctxt *ld.Link, r *ld.Reloc, sectoff int64) int {

src/cmd/link/internal/ppc64/asm.go

@@ -240,7 +240,7 @@ func gencallstub(ctxt *ld.Link, abicase int, stub *ld.Symbol, targ *ld.Symbol) {
 	ld.Adduint32(ctxt, stub, 0x4e800420) // bctr
 }
 
-func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
+func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) bool {
 	targ := r.Sym
 	ctxt.Cursym = s
 
@@ -248,7 +248,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 	default:
 		if r.Type >= 256 {
 			ctxt.Diag("unexpected relocation type %d", r.Type)
-			return
+			return false
 		}
 
 		// Handle relocations found in ELF object files.
@@ -267,7 +267,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			ctxt.Diag("unexpected R_PPC64_REL24 for dyn import")
 		}
 
-		return
+		return true
 
 	case 256 + ld.R_PPC_REL32:
 		r.Type = obj.R_PCREL
@@ -277,7 +277,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			ctxt.Diag("unexpected R_PPC_REL32 for dyn import")
 		}
 
-		return
+		return true
 
 	case 256 + ld.R_PPC64_ADDR64:
 		r.Type = obj.R_ADDR
@@ -292,65 +292,65 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			r.Type = 256 // ignore during relocsym
 		}
 
-		return
+		return true
 
 	case 256 + ld.R_PPC64_TOC16:
 		r.Type = obj.R_POWER_TOC
 		r.Variant = ld.RV_POWER_LO | ld.RV_CHECK_OVERFLOW
-		return
+		return true
 
 	case 256 + ld.R_PPC64_TOC16_LO:
 		r.Type = obj.R_POWER_TOC
 		r.Variant = ld.RV_POWER_LO
-		return
+		return true
 
 	case 256 + ld.R_PPC64_TOC16_HA:
 		r.Type = obj.R_POWER_TOC
 		r.Variant = ld.RV_POWER_HA | ld.RV_CHECK_OVERFLOW
-		return
+		return true
 
 	case 256 + ld.R_PPC64_TOC16_HI:
 		r.Type = obj.R_POWER_TOC
 		r.Variant = ld.RV_POWER_HI | ld.RV_CHECK_OVERFLOW
-		return
+		return true
 
 	case 256 + ld.R_PPC64_TOC16_DS:
 		r.Type = obj.R_POWER_TOC
 		r.Variant = ld.RV_POWER_DS | ld.RV_CHECK_OVERFLOW
-		return
+		return true
 
 	case 256 + ld.R_PPC64_TOC16_LO_DS:
 		r.Type = obj.R_POWER_TOC
 		r.Variant = ld.RV_POWER_DS
-		return
+		return true
 
 	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
+		return true
 
 	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
+		return true
 
 	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
+		return true
 	}
 
 	// Handle references to ELF symbols from our own object files.
 	if targ.Type != obj.SDYNIMPORT {
-		return
+		return true
 	}
 
 	// TODO(austin): Translate our relocations to ELF
 
-	ctxt.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ.Name, r.Type, targ.Type)
+	return false
 }
 
 func elfreloc1(ctxt *ld.Link, r *ld.Reloc, sectoff int64) int {

src/cmd/link/internal/s390x/asm.go

@@ -98,7 +98,7 @@ func gentext(ctxt *ld.Link) {
 	ld.Addaddr(ctxt, initarray_entry, initfunc)
 }
 
-func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
+func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) bool {
 	targ := r.Sym
 	ctxt.Cursym = s
 
@@ -106,14 +106,14 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 	default:
 		if r.Type >= 256 {
 			ctxt.Diag("unexpected relocation type %d", r.Type)
-			return
+			return false
 		}
 
 		// Handle relocations found in ELF object files.
 	case 256 + ld.R_390_12,
 		256 + ld.R_390_GOT12:
 		ctxt.Diag("s390x 12-bit relocations have not been implemented (relocation type %d)", r.Type-256)
-		return
+		return false
 
 	case 256 + ld.R_390_8,
 		256 + ld.R_390_16,
@@ -123,7 +123,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			ctxt.Diag("unexpected R_390_nn relocation for dynamic symbol %s", targ.Name)
 		}
 		r.Type = obj.R_ADDR
-		return
+		return true
 
 	case 256 + ld.R_390_PC16,
 		256 + ld.R_390_PC32,
@@ -136,13 +136,13 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		}
 		r.Type = obj.R_PCREL
 		r.Add += int64(r.Siz)
-		return
+		return true
 
 	case 256 + ld.R_390_GOT16,
 		256 + ld.R_390_GOT32,
 		256 + ld.R_390_GOT64:
 		ctxt.Diag("unimplemented S390x relocation: %v", r.Type-256)
-		return
+		return true
 
 	case 256 + ld.R_390_PLT16DBL,
 		256 + ld.R_390_PLT32DBL:
@@ -154,7 +154,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			r.Sym = ld.Linklookup(ctxt, ".plt", 0)
 			r.Add += int64(targ.Plt)
 		}
-		return
+		return true
 
 	case 256 + ld.R_390_PLT32,
 		256 + ld.R_390_PLT64:
@@ -165,32 +165,36 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			r.Sym = ld.Linklookup(ctxt, ".plt", 0)
 			r.Add += int64(targ.Plt)
 		}
-		return
+		return true
 
 	case 256 + ld.R_390_COPY:
 		ctxt.Diag("unimplemented S390x relocation: %v", r.Type-256)
+		return false
 
 	case 256 + ld.R_390_GLOB_DAT:
 		ctxt.Diag("unimplemented S390x relocation: %v", r.Type-256)
+		return false
 
 	case 256 + ld.R_390_JMP_SLOT:
 		ctxt.Diag("unimplemented S390x relocation: %v", r.Type-256)
+		return false
 
 	case 256 + ld.R_390_RELATIVE:
 		ctxt.Diag("unimplemented S390x relocation: %v", r.Type-256)
+		return false
 
 	case 256 + ld.R_390_GOTOFF:
 		if targ.Type == obj.SDYNIMPORT {
 			ctxt.Diag("unexpected R_390_GOTOFF relocation for dynamic symbol %s", targ.Name)
 		}
 		r.Type = obj.R_GOTOFF
-		return
+		return true
 
 	case 256 + ld.R_390_GOTPC:
 		r.Type = obj.R_PCREL
 		r.Sym = ld.Linklookup(ctxt, ".got", 0)
 		r.Add += int64(r.Siz)
-		return
+		return true
 
 	case 256 + ld.R_390_PC16DBL,
 		256 + ld.R_390_PC32DBL:
@@ -200,14 +204,14 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		if targ.Type == obj.SDYNIMPORT {
 			ctxt.Diag("unexpected R_390_PCnnDBL relocation for dynamic symbol %s", targ.Name)
 		}
-		return
+		return true
 
 	case 256 + ld.R_390_GOTPCDBL:
 		r.Type = obj.R_PCREL
 		r.Variant = ld.RV_390_DBL
 		r.Sym = ld.Linklookup(ctxt, ".got", 0)
 		r.Add += int64(r.Siz)
-		return
+		return true
 
 	case 256 + ld.R_390_GOTENT:
 		addgotsym(ctxt, targ)
@@ -217,14 +221,14 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		r.Sym = ld.Linklookup(ctxt, ".got", 0)
 		r.Add += int64(targ.Got)
 		r.Add += int64(r.Siz)
-		return
+		return true
 	}
 	// Handle references to ELF symbols from our own object files.
 	if targ.Type != obj.SDYNIMPORT {
-		return
+		return true
 	}
 
-	ctxt.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ.Name, r.Type, targ.Type)
+	return false
 }
 
 func elfreloc1(ctxt *ld.Link, r *ld.Reloc, sectoff int64) int {

src/cmd/link/internal/x86/asm.go

@@ -159,7 +159,7 @@ func gentext(ctxt *ld.Link) {
 	ld.Addaddr(ctxt, initarray_entry, initfunc)
 }
 
-func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
+func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) bool {
 	targ := r.Sym
 	ctxt.Cursym = s
 
@@ -167,7 +167,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 	default:
 		if r.Type >= 256 {
 			ctxt.Diag("unexpected relocation type %d", r.Type)
-			return
+			return false
 		}
 
 		// Handle relocations found in ELF object files.
@@ -180,7 +180,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 		}
 		r.Type = obj.R_PCREL
 		r.Add += 4
-		return
+		return true
 
 	case 256 + ld.R_386_PLT32:
 		r.Type = obj.R_PCREL
@@ -191,7 +191,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			r.Add += int64(targ.Plt)
 		}
 
-		return
+		return true
 
 	case 256 + ld.R_386_GOT32, 256 + ld.R_386_GOT32X:
 		if targ.Type != obj.SDYNIMPORT {
@@ -201,7 +201,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 				s.P[r.Off-2] = 0x8d
 
 				r.Type = obj.R_GOTOFF
-				return
+				return true
 			}
 
 			if r.Off >= 2 && s.P[r.Off-2] == 0xff && s.P[r.Off-1] == 0xb3 {
@@ -211,42 +211,42 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 
 				s.P[r.Off-1] = 0x68
 				r.Type = obj.R_ADDR
-				return
+				return true
 			}
 
 			ctxt.Diag("unexpected GOT reloc for non-dynamic symbol %s", targ.Name)
-			return
+			return false
 		}
 
 		addgotsym(ctxt, targ)
 		r.Type = obj.R_CONST // write r->add during relocsym
 		r.Sym = nil
 		r.Add += int64(targ.Got)
-		return
+		return true
 
 	case 256 + ld.R_386_GOTOFF:
 		r.Type = obj.R_GOTOFF
-		return
+		return true
 
 	case 256 + ld.R_386_GOTPC:
 		r.Type = obj.R_PCREL
 		r.Sym = ld.Linklookup(ctxt, ".got", 0)
 		r.Add += 4
-		return
+		return true
 
 	case 256 + ld.R_386_32:
 		if targ.Type == obj.SDYNIMPORT {
 			ctxt.Diag("unexpected R_386_32 relocation for dynamic symbol %s", targ.Name)
 		}
 		r.Type = obj.R_ADDR
-		return
+		return true
 
 	case 512 + ld.MACHO_GENERIC_RELOC_VANILLA*2 + 0:
 		r.Type = obj.R_ADDR
 		if targ.Type == obj.SDYNIMPORT {
 			ctxt.Diag("unexpected reloc for dynamic symbol %s", targ.Name)
 		}
-		return
+		return true
 
 	case 512 + ld.MACHO_GENERIC_RELOC_VANILLA*2 + 1:
 		if targ.Type == obj.SDYNIMPORT {
@@ -254,11 +254,11 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			r.Sym = ld.Linklookup(ctxt, ".plt", 0)
 			r.Add = int64(targ.Plt)
 			r.Type = obj.R_PCREL
-			return
+			return true
 		}
 
 		r.Type = obj.R_PCREL
-		return
+		return true
 
 	case 512 + ld.MACHO_FAKE_GOTPCREL:
 		if targ.Type != obj.SDYNIMPORT {
@@ -266,33 +266,32 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			// turn MOVL of GOT entry into LEAL of symbol itself
 			if r.Off < 2 || s.P[r.Off-2] != 0x8b {
 				ctxt.Diag("unexpected GOT reloc for non-dynamic symbol %s", targ.Name)
-				return
+				return false
 			}
 
 			s.P[r.Off-2] = 0x8d
 			r.Type = obj.R_PCREL
-			return
+			return true
 		}
 
 		addgotsym(ctxt, targ)
 		r.Sym = ld.Linklookup(ctxt, ".got", 0)
 		r.Add += int64(targ.Got)
 		r.Type = obj.R_PCREL
-		return
+		return true
 	}
 
 	// Handle references to ELF symbols from our own object files.
 	if targ.Type != obj.SDYNIMPORT {
-		return
+		return true
 	}
-
 	switch r.Type {
 	case obj.R_CALL,
 		obj.R_PCREL:
 		addpltsym(ctxt, targ)
 		r.Sym = ld.Linklookup(ctxt, ".plt", 0)
 		r.Add = int64(targ.Plt)
-		return
+		return true
 
 	case obj.R_ADDR:
 		if s.Type != obj.SDATA {
@@ -305,7 +304,7 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			ld.Adduint32(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
+			return true
 		}
 
 		if ld.Headtype == obj.Hdarwin && s.Size == int64(ld.SysArch.PtrSize) && r.Off == 0 {
@@ -330,17 +329,16 @@ func adddynrel(ctxt *ld.Link, s *ld.Symbol, r *ld.Reloc) {
 			ld.Adduint32(ctxt, got, 0)
 			ld.Adduint32(ctxt, ld.Linklookup(ctxt, ".linkedit.got", 0), uint32(targ.Dynid))
 			r.Type = 256 // ignore during relocsym
-			return
+			return true
 		}
 
 		if (ld.Headtype == obj.Hwindows || ld.Headtype == obj.Hwindowsgui) && s.Size == int64(ld.SysArch.PtrSize) {
 			// nothing to do, the relocation will be laid out in pereloc1
-			return
+			return true
 		}
 	}
 
-	ctxt.Cursym = s
-	ctxt.Diag("unsupported relocation for dynamic symbol %s (type=%d stype=%d)", targ.Name, r.Type, targ.Type)
+	return false
 }
 
 func elfreloc1(ctxt *ld.Link, r *ld.Reloc, sectoff int64) int {