commit b066b0e7a6fb9c6925a89fa68222a5322099f4f7
Author: Clément Chigot <clement.chigot@atos.net>
Date:   Mon Jan 7 10:22:42 2019 +0100

    cmd/link: fix debug_frame generation for Dwarf64
    
    This commit fixes the dwarf section .debug_frame when Dwarf 64 bits is
    used.
    TestGdbAutotmpTypes is disabled in short mode on aix/ppc64 because it takes
    more than 1 minute.
    
    Fixes #28558
    
    Change-Id: I0ecd9c47fb017cf4bd44725a83a0016c7bb94633

diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go
index a150306df9..c226886557 100644
--- a/src/cmd/link/internal/ld/dwarf.go
+++ b/src/cmd/link/internal/ld/dwarf.go
@@ -1391,13 +1391,22 @@ func writeframes(ctxt *Link, syms []*sym.Symbol) []*sym.Symbol {
 	fs.Type = sym.SDWARFSECT
 	syms = append(syms, fs)
 
+	// Length field is 4 bytes on Dwarf32 and 12 bytes on Dwarf64
+	lengthFieldSize := int64(4)
+	if isDwarf64(ctxt) {
+		lengthFieldSize += 8
+	}
+
 	// Emit the CIE, Section 6.4.1
 	cieReserve := uint32(16)
 	if haslinkregister(ctxt) {
 		cieReserve = 32
 	}
+	if isDwarf64(ctxt) {
+		cieReserve += 4 // 4 bytes added for cid
+	}
 	createUnitLength(ctxt, fs, uint64(cieReserve))             // initial length, must be multiple of thearch.ptrsize
-	addDwarfAddrField(ctxt, fs, 0xffffffff)                    // cid.
+	addDwarfAddrField(ctxt, fs, ^uint64(0))                    // cid
 	fs.AddUint8(3)                                             // dwarf version (appendix F)
 	fs.AddUint8(0)                                             // augmentation ""
 	dwarf.Uleb128put(dwarfctxt, fs, 1)                         // code_alignment_factor
@@ -1423,8 +1432,7 @@ func writeframes(ctxt *Link, syms []*sym.Symbol) []*sym.Symbol {
 		dwarf.Uleb128put(dwarfctxt, fs, int64(-ctxt.Arch.PtrSize)/dataAlignmentFactor) // ...is saved at [CFA - (PtrSize/4)].
 	}
 
-	// 4 is to exclude the length field.
-	pad := int64(cieReserve) + 4 - fs.Size
+	pad := int64(cieReserve) + lengthFieldSize - fs.Size
 
 	if pad < 0 {
 		Exitf("dwarf: cieReserve too small by %d bytes.", -pad)
@@ -1480,10 +1488,16 @@ func writeframes(ctxt *Link, syms []*sym.Symbol) []*sym.Symbol {
 
 		// 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
+		//	4/8 bytes: Pointer to the CIE above, at offset 0
 		//	ptrsize: initial location
 		//	ptrsize: address range
-		fs.AddUint32(ctxt.Arch, uint32(4+2*ctxt.Arch.PtrSize+len(deltaBuf))) // length (excludes itself)
+
+		fdeLength := uint64(4 + 2*ctxt.Arch.PtrSize + len(deltaBuf))
+		if isDwarf64(ctxt) {
+			fdeLength += 4 // 4 bytes added for CIE pointer
+		}
+		createUnitLength(ctxt, fs, fdeLength)
+
 		if ctxt.LinkMode == LinkExternal {
 			addDwarfAddrRef(ctxt, fs, fs)
 		} else {
diff --git a/src/runtime/runtime-gdb_test.go b/src/runtime/runtime-gdb_test.go
index d0f905e4d7..d47c7c2262 100644
--- a/src/runtime/runtime-gdb_test.go
+++ b/src/runtime/runtime-gdb_test.go
@@ -36,8 +36,6 @@ func checkGdbEnvironment(t *testing.T) {
 		if runtime.GOARCH == "mips" {
 			t.Skip("skipping gdb tests on linux/mips; see https://golang.org/issue/25939")
 		}
-	case "aix":
-		t.Skip("gdb does not work on AIX; see https://golang.org/issue/28558")
 	case "freebsd":
 		t.Skip("skipping gdb tests on FreeBSD; see https://golang.org/issue/29508")
 	}
@@ -396,6 +394,10 @@ func TestGdbAutotmpTypes(t *testing.T) {
 	t.Parallel()
 	checkGdbVersion(t)
 
+	if runtime.GOOS == "aix" && testing.Short() {
+		t.Skip("TestGdbAutotmpTypes is too slow on aix/ppc64")
+	}
+
 	dir, err := ioutil.TempDir("", "go-build")
 	if err != nil {
 		t.Fatalf("failed to create temp directory: %v", err)