Merge from trunk revision 3089f5feef36810c625b5813370a97b4ecc841f8

63 files changed, 946 insertions, 425 deletions

diff --git a/libgo/MERGE b/libgo/MERGE
index ad239c9..b753907 100644
--- a/libgo/MERGE
+++ b/libgo/MERGE
@@ -1,4 +1,4 @@
-0e953add9656c32a788e06438cd7b533e968b7f8
+c53315d6cf1b4bfea6ff356b4a1524778c683bb9
 
 The first line of this file holds the git revision number of the
 last merge done from the master library sources.
diff --git a/libgo/Makefile.am b/libgo/Makefile.am
index f7a163e..4d3e54e 100644
--- a/libgo/Makefile.am
+++ b/libgo/Makefile.am
@@ -439,7 +439,6 @@ runtime_files = \
 	runtime/go-assert.c \
 	runtime/go-caller.c \
 	runtime/go-callers.c \
-	runtime/go-cdiv.c \
 	runtime/go-cgo.c \
 	runtime/go-construct-map.c \
 	runtime/go-ffi.c \
diff --git a/libgo/Makefile.in b/libgo/Makefile.in
index ba202a6..d6ac066 100644
--- a/libgo/Makefile.in
+++ b/libgo/Makefile.in
@@ -240,12 +240,11 @@ am__objects_2 = $(am__objects_1)
 @LIBGO_IS_RTEMS_TRUE@am__objects_3 =  \
 @LIBGO_IS_RTEMS_TRUE@	runtime/rtems-task-variable-add.lo
 am__objects_4 = runtime/aeshash.lo runtime/go-assert.lo \
-	runtime/go-caller.lo runtime/go-callers.lo runtime/go-cdiv.lo \
-	runtime/go-cgo.lo runtime/go-construct-map.lo \
-	runtime/go-ffi.lo runtime/go-fieldtrack.lo \
-	runtime/go-matherr.lo runtime/go-memclr.lo \
-	runtime/go-memequal.lo runtime/go-nanotime.lo \
-	runtime/go-now.lo runtime/go-nosys.lo \
+	runtime/go-caller.lo runtime/go-callers.lo runtime/go-cgo.lo \
+	runtime/go-construct-map.lo runtime/go-ffi.lo \
+	runtime/go-fieldtrack.lo runtime/go-matherr.lo \
+	runtime/go-memclr.lo runtime/go-memequal.lo \
+	runtime/go-nanotime.lo runtime/go-now.lo runtime/go-nosys.lo \
 	runtime/go-reflect-call.lo runtime/go-setenv.lo \
 	runtime/go-signal.lo runtime/go-unsafe-pointer.lo \
 	runtime/go-unsetenv.lo runtime/go-unwind.lo \
@@ -892,7 +891,6 @@ runtime_files = \
 	runtime/go-assert.c \
 	runtime/go-caller.c \
 	runtime/go-callers.c \
-	runtime/go-cdiv.c \
 	runtime/go-cgo.c \
 	runtime/go-construct-map.c \
 	runtime/go-ffi.c \
@@ -1343,8 +1341,6 @@ runtime/go-caller.lo: runtime/$(am__dirstamp) \
 	runtime/$(DEPDIR)/$(am__dirstamp)
 runtime/go-callers.lo: runtime/$(am__dirstamp) \
 	runtime/$(DEPDIR)/$(am__dirstamp)
-runtime/go-cdiv.lo: runtime/$(am__dirstamp) \
-	runtime/$(DEPDIR)/$(am__dirstamp)
 runtime/go-cgo.lo: runtime/$(am__dirstamp) \
 	runtime/$(DEPDIR)/$(am__dirstamp)
 runtime/go-construct-map.lo: runtime/$(am__dirstamp) \
@@ -1417,7 +1413,6 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-assert.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-caller.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-callers.Plo@am__quote@
-@AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-cdiv.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-cgo.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-construct-map.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@runtime/$(DEPDIR)/go-context.Plo@am__quote@
diff --git a/libgo/VERSION b/libgo/VERSION
index baff222..7014547 100644
--- a/libgo/VERSION
+++ b/libgo/VERSION
@@ -1 +1 @@
-go1.15.4
+go1.15.5
diff --git a/libgo/check-packages.txt b/libgo/check-packages.txt
index efa7d19..da77e84 100644
--- a/libgo/check-packages.txt
+++ b/libgo/check-packages.txt
@@ -22,6 +22,7 @@ cmd/go/internal/work
 cmd/internal/buildid
 cmd/internal/edit
 cmd/internal/objabi
+cmd/internal/pkgpath
 cmd/internal/test2json
 compress/bzip2
 compress/flate
diff --git a/libgo/configure b/libgo/configure
index e7379f8..1d7d007 100755
--- a/libgo/configure
+++ b/libgo/configure
@@ -2551,7 +2551,7 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 ac_config_headers="$ac_config_headers config.h"
 
 
-libtool_VERSION=17:0:0
+libtool_VERSION=18:0:0
 
 
 # Default to --enable-multilib
diff --git a/libgo/configure.ac b/libgo/configure.ac
index 80537f5..5013f41 100644
--- a/libgo/configure.ac
+++ b/libgo/configure.ac
@@ -10,7 +10,7 @@ AC_INIT(package-unused, version-unused,, libgo)
 AC_CONFIG_SRCDIR(Makefile.am)
 AC_CONFIG_HEADER(config.h)
 
-libtool_VERSION=17:0:0
+libtool_VERSION=18:0:0
 AC_SUBST(libtool_VERSION)
 
 AM_ENABLE_MULTILIB(, ..)
diff --git a/libgo/go/cmd/cgo/main.go b/libgo/go/cmd/cgo/main.go
index 7fc2508..4952118 100644
--- a/libgo/go/cmd/cgo/main.go
+++ b/libgo/go/cmd/cgo/main.go
@@ -244,8 +244,7 @@ var exportHeader = flag.String("exportheader", "", "where to write export header
 var gccgo = flag.Bool("gccgo", false, "generate files for use with gccgo")
 var gccgoprefix = flag.String("gccgoprefix", "", "-fgo-prefix option used with gccgo")
 var gccgopkgpath = flag.String("gccgopkgpath", "", "-fgo-pkgpath option used with gccgo")
-var gccgoMangleCheckDone bool
-var gccgoNewmanglingInEffect bool
+var gccgoMangler func(string) string
 var importRuntimeCgo = flag.Bool("import_runtime_cgo", true, "import runtime/cgo in generated code")
 var importSyscall = flag.Bool("import_syscall", true, "import syscall in generated code")
 var goarch, goos string
diff --git a/libgo/go/cmd/cgo/out.go b/libgo/go/cmd/cgo/out.go
index dd03f7d..1c143d7 100644
--- a/libgo/go/cmd/cgo/out.go
+++ b/libgo/go/cmd/cgo/out.go
@@ -6,6 +6,7 @@ package main
 
 import (
 	"bytes"
+	"cmd/internal/pkgpath"
 	"debug/elf"
 	"debug/macho"
 	"debug/pe"
@@ -15,7 +16,6 @@ import (
 	"go/token"
 	"internal/xcoff"
 	"io"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -191,7 +191,7 @@ func (p *Package) writeDefs() {
 			panic(fmt.Errorf("invalid var kind %q", n.Kind))
 		}
 		if *gccgo {
-			fmt.Fprintf(fc, `extern void *%s __asm__("%s.%s");`, n.Mangle, gccgoSymbolPrefix, n.Mangle)
+			fmt.Fprintf(fc, `extern void *%s __asm__("%s.%s");`, n.Mangle, gccgoSymbolPrefix, gccgoToSymbol(n.Mangle))
 			fmt.Fprintf(&gccgoInit, "\t%s = &%s;\n", n.Mangle, n.C)
 			fmt.Fprintf(fc, "\n")
 		}
@@ -341,6 +341,8 @@ func dynimport(obj string) {
 			if s.Version != "" {
 				targ += "#" + s.Version
 			}
+			checkImportSymName(s.Name)
+			checkImportSymName(targ)
 			fmt.Fprintf(stdout, "//go:cgo_import_dynamic %s %s %q\n", s.Name, targ, s.Library)
 		}
 		lib, _ := f.ImportedLibraries()
@@ -356,6 +358,7 @@ func dynimport(obj string) {
 			if len(s) > 0 && s[0] == '_' {
 				s = s[1:]
 			}
+			checkImportSymName(s)
 			fmt.Fprintf(stdout, "//go:cgo_import_dynamic %s %s %q\n", s, s, "")
 		}
 		lib, _ := f.ImportedLibraries()
@@ -370,6 +373,8 @@ func dynimport(obj string) {
 		for _, s := range sym {
 			ss := strings.Split(s, ":")
 			name := strings.Split(ss[0], "@")[0]
+			checkImportSymName(name)
+			checkImportSymName(ss[0])
 			fmt.Fprintf(stdout, "//go:cgo_import_dynamic %s %s %q\n", name, ss[0], strings.ToLower(ss[1]))
 		}
 		return
@@ -387,6 +392,7 @@ func dynimport(obj string) {
 				// Go symbols.
 				continue
 			}
+			checkImportSymName(s.Name)
 			fmt.Fprintf(stdout, "//go:cgo_import_dynamic %s %s %q\n", s.Name, s.Name, s.Library)
 		}
 		lib, err := f.ImportedLibraries()
@@ -402,6 +408,23 @@ func dynimport(obj string) {
 	fatalf("cannot parse %s as ELF, Mach-O, PE or XCOFF", obj)
 }
 
+// checkImportSymName checks a symbol name we are going to emit as part
+// of a //go:cgo_import_dynamic pragma. These names come from object
+// files, so they may be corrupt. We are going to emit them unquoted,
+// so while they don't need to be valid symbol names (and in some cases,
+// involving symbol versions, they won't be) they must contain only
+// graphic characters and must not contain Go comments.
+func checkImportSymName(s string) {
+	for _, c := range s {
+		if !unicode.IsGraphic(c) || unicode.IsSpace(c) {
+			fatalf("dynamic symbol %q contains unsupported character", s)
+		}
+	}
+	if strings.Index(s, "//") >= 0 || strings.Index(s, "/*") >= 0 {
+		fatalf("dynamic symbol %q contains Go comment")
+	}
+}
+
 // Construct a gcc struct matching the gc argument frame.
 // Assumes that in gcc, char is 1 byte, short 2 bytes, int 4 bytes, long long 8 bytes.
 // These assumptions are checked by the gccProlog.
@@ -1168,7 +1191,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 		// will not be able to link against it from the C
 		// code.
 		goName := "Cgoexp_" + exp.ExpName
-		fmt.Fprintf(fgcc, `extern %s %s %s __asm__("%s.%s");`, cRet, goName, cParams, gccgoSymbolPrefix, goName)
+		fmt.Fprintf(fgcc, `extern %s %s %s __asm__("%s.%s");`, cRet, goName, cParams, gccgoSymbolPrefix, gccgoToSymbol(goName))
 		fmt.Fprint(fgcc, "\n")
 
 		fmt.Fprint(fgcc, "\nCGO_NO_SANITIZE_THREAD\n")
@@ -1202,7 +1225,7 @@ func (p *Package) writeGccgoExports(fgo2, fm, fgcc, fgcch io.Writer) {
 		fmt.Fprint(fgcc, "}\n")
 
 		// Dummy declaration for _cgo_main.c
-		fmt.Fprintf(fm, `char %s[1] __asm__("%s.%s");`, goName, gccgoSymbolPrefix, goName)
+		fmt.Fprintf(fm, `char %s[1] __asm__("%s.%s");`, goName, gccgoSymbolPrefix, gccgoToSymbol(goName))
 		fmt.Fprint(fm, "\n")
 
 		// For gccgo we use a wrapper function in Go, in order
@@ -1286,112 +1309,23 @@ func (p *Package) writeExportHeader(fgcch io.Writer) {
 	fmt.Fprintf(fgcch, "%s\n", p.gccExportHeaderProlog())
 }
 
-// gccgoUsesNewMangling reports whether gccgo uses the new collision-free
-// packagepath mangling scheme (see determineGccgoManglingScheme for more
-// info).
-func gccgoUsesNewMangling() bool {
-	if !gccgoMangleCheckDone {
-		gccgoNewmanglingInEffect = determineGccgoManglingScheme()
-		gccgoMangleCheckDone = true
-	}
-	return gccgoNewmanglingInEffect
-}
-
-const mangleCheckCode = `
-package läufer
-func Run(x int) int {
-  return 1
-}
-`
-
-// determineGccgoManglingScheme performs a runtime test to see which
-// flavor of packagepath mangling gccgo is using. Older versions of
-// gccgo use a simple mangling scheme where there can be collisions
-// between packages whose paths are different but mangle to the same
-// string. More recent versions of gccgo use a new mangler that avoids
-// these collisions. Return value is whether gccgo uses the new mangling.
-func determineGccgoManglingScheme() bool {
-
-	// Emit a small Go file for gccgo to compile.
-	filepat := "*_gccgo_manglecheck.go"
-	var f *os.File
-	var err error
-	if f, err = ioutil.TempFile(*objDir, filepat); err != nil {
-		fatalf("%v", err)
-	}
-	gofilename := f.Name()
-	defer os.Remove(gofilename)
-
-	if err = ioutil.WriteFile(gofilename, []byte(mangleCheckCode), 0666); err != nil {
-		fatalf("%v", err)
-	}
-
-	// Compile with gccgo, capturing generated assembly.
-	gccgocmd := os.Getenv("GCCGO")
-	if gccgocmd == "" {
-		gpath, gerr := exec.LookPath("gccgo")
-		if gerr != nil {
-			fatalf("unable to locate gccgo: %v", gerr)
-		}
-		gccgocmd = gpath
-	}
-	cmd := exec.Command(gccgocmd, "-S", "-o", "-", gofilename)
-	buf, cerr := cmd.CombinedOutput()
-	if cerr != nil {
-		fatalf("%s", cerr)
-	}
-
-	// New mangling: expect go.l..u00e4ufer.Run
-	// Old mangling: expect go.l__ufer.Run
-	return regexp.MustCompile(`go\.l\.\.u00e4ufer\.Run`).Match(buf)
-}
-
-// gccgoPkgpathToSymbolNew converts a package path to a gccgo-style
-// package symbol.
-func gccgoPkgpathToSymbolNew(ppath string) string {
-	bsl := []byte{}
-	changed := false
-	for _, c := range []byte(ppath) {
-		switch {
-		case 'A' <= c && c <= 'Z', 'a' <= c && c <= 'z',
-			'0' <= c && c <= '9', c == '_':
-			bsl = append(bsl, c)
-		case c == '.':
-			bsl = append(bsl, ".x2e"...)
-		default:
-			changed = true
-			encbytes := []byte(fmt.Sprintf("..z%02x", c))
-			bsl = append(bsl, encbytes...)
+// gccgoToSymbol converts a name to a mangled symbol for gccgo.
+func gccgoToSymbol(ppath string) string {
+	if gccgoMangler == nil {
+		var err error
+		cmd := os.Getenv("GCCGO")
+		if cmd == "" {
+			cmd, err = exec.LookPath("gccgo")
+			if err != nil {
+				fatalf("unable to locate gccgo: %v", err)
+			}
 		}
-	}
-	if !changed {
-		return ppath
-	}
-	return string(bsl)
-}
-
-// gccgoPkgpathToSymbolOld converts a package path to a gccgo-style
-// package symbol using the older mangling scheme.
-func gccgoPkgpathToSymbolOld(ppath string) string {
-	clean := func(r rune) rune {
-		switch {
-		case 'A' <= r && r <= 'Z', 'a' <= r && r <= 'z',
-			'0' <= r && r <= '9':
-			return r
+		gccgoMangler, err = pkgpath.ToSymbolFunc(cmd, *objDir)
+		if err != nil {
+			fatalf("%v", err)
 		}
-		return '_'
-	}
-	return strings.Map(clean, ppath)
-}
-
-// gccgoPkgpathToSymbol converts a package path to a mangled packagepath
-// symbol.
-func gccgoPkgpathToSymbol(ppath string) string {
-	if gccgoUsesNewMangling() {
-		return gccgoPkgpathToSymbolNew(ppath)
-	} else {
-		return gccgoPkgpathToSymbolOld(ppath)
 	}
+	return gccgoMangler(ppath)
 }
 
 // Return the package prefix when using gccgo.
@@ -1401,12 +1335,12 @@ func (p *Package) gccgoSymbolPrefix() string {
 	}
 
 	if *gccgopkgpath != "" {
-		return gccgoPkgpathToSymbol(*gccgopkgpath)
+		return gccgoToSymbol(*gccgopkgpath)
 	}
 	if *gccgoprefix == "" && p.PackageName == "main" {
 		return "main"
 	}
-	prefix := gccgoPkgpathToSymbol(*gccgoprefix)
+	prefix := gccgoToSymbol(*gccgoprefix)
 	if prefix == "" {
 		prefix = "go"
 	}
@@ -1798,8 +1732,12 @@ void _cgoPREFIX_Cfunc__Cmalloc(void *v) {
 `
 
 func (p *Package) cPrologGccgo() string {
-	return strings.Replace(strings.Replace(cPrologGccgo, "PREFIX", cPrefix, -1),
-		"GCCGOSYMBOLPREF", p.gccgoSymbolPrefix(), -1)
+	r := strings.NewReplacer(
+		"PREFIX", cPrefix,
+		"GCCGOSYMBOLPREF", p.gccgoSymbolPrefix(),
+		"_cgoCheckPointer", gccgoToSymbol("_cgoCheckPointer"),
+		"_cgoCheckResult", gccgoToSymbol("_cgoCheckResult"))
+	return r.Replace(cPrologGccgo)
 }
 
 const cPrologGccgo = `
diff --git a/libgo/go/cmd/go/internal/work/exec.go b/libgo/go/cmd/go/internal/work/exec.go
index 65f3011..4f68943 100644
--- a/libgo/go/cmd/go/internal/work/exec.go
+++ b/libgo/go/cmd/go/internal/work/exec.go
@@ -2723,6 +2723,66 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 		noCompiler()
 	}
 
+	// Double check the //go:cgo_ldflag comments in the generated files.
+	// The compiler only permits such comments in files whose base name
+	// starts with "_cgo_". Make sure that the comments in those files
+	// are safe. This is a backstop against people somehow smuggling
+	// such a comment into a file generated by cgo.
+	if cfg.BuildToolchainName == "gc" && !cfg.BuildN {
+		var flags []string
+		for _, f := range outGo {
+			if !strings.HasPrefix(filepath.Base(f), "_cgo_") {
+				continue
+			}
+
+			src, err := ioutil.ReadFile(f)
+			if err != nil {
+				return nil, nil, err
+			}
+
+			const cgoLdflag = "//go:cgo_ldflag"
+			idx := bytes.Index(src, []byte(cgoLdflag))
+			for idx >= 0 {
+				// We are looking at //go:cgo_ldflag.
+				// Find start of line.
+				start := bytes.LastIndex(src[:idx], []byte("\n"))
+				if start == -1 {
+					start = 0
+				}
+
+				// Find end of line.
+				end := bytes.Index(src[idx:], []byte("\n"))
+				if end == -1 {
+					end = len(src)
+				} else {
+					end += idx
+				}
+
+				// Check for first line comment in line.
+				// We don't worry about /* */ comments,
+				// which normally won't appear in files
+				// generated by cgo.
+				commentStart := bytes.Index(src[start:], []byte("//"))
+				commentStart += start
+				// If that line comment is //go:cgo_ldflag,
+				// it's a match.
+				if bytes.HasPrefix(src[commentStart:], []byte(cgoLdflag)) {
+					// Pull out the flag, and unquote it.
+					// This is what the compiler does.
+					flag := string(src[idx+len(cgoLdflag) : end])
+					flag = strings.TrimSpace(flag)
+					flag = strings.Trim(flag, `"`)
+					flags = append(flags, flag)
+				}
+				src = src[end:]
+				idx = bytes.Index(src, []byte(cgoLdflag))
+			}
+		}
+		if err := checkLinkerFlags("LDFLAGS", "go:cgo_ldflag", flags); err != nil {
+			return nil, nil, err
+		}
+	}
+
 	return outGo, outObj, nil
 }
 
diff --git a/libgo/go/cmd/go/internal/work/gccgo.go b/libgo/go/cmd/go/internal/work/gccgo.go
index 63d5c62..dbaff70 100644
--- a/libgo/go/cmd/go/internal/work/gccgo.go
+++ b/libgo/go/cmd/go/internal/work/gccgo.go
@@ -11,11 +11,13 @@ import (
 	"os/exec"
 	"path/filepath"
 	"strings"
+	"sync"
 
 	"cmd/go/internal/base"
 	"cmd/go/internal/cfg"
 	"cmd/go/internal/load"
 	"cmd/go/internal/str"
+	"cmd/internal/pkgpath"
 )
 
 // The Gccgo toolchain.
@@ -174,7 +176,7 @@ func (tools gccgoToolchain) asm(b *Builder, a *Action, sfiles []string) ([]strin
 		ofiles = append(ofiles, ofile)
 		sfile = mkAbs(p.Dir, sfile)
 		defs := []string{"-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch}
-		if pkgpath := gccgoCleanPkgpath(p); pkgpath != "" {
+		if pkgpath := tools.gccgoCleanPkgpath(b, p); pkgpath != "" {
 			defs = append(defs, `-D`, `GOPKGPATH=`+pkgpath)
 		}
 		defs = tools.maybePIC(defs)
@@ -556,7 +558,7 @@ func (tools gccgoToolchain) cc(b *Builder, a *Action, ofile, cfile string) error
 	cfile = mkAbs(p.Dir, cfile)
 	defs := []string{"-D", "GOOS_" + cfg.Goos, "-D", "GOARCH_" + cfg.Goarch}
 	defs = append(defs, b.gccArchArgs()...)
-	if pkgpath := gccgoCleanPkgpath(p); pkgpath != "" {
+	if pkgpath := tools.gccgoCleanPkgpath(b, p); pkgpath != "" {
 		defs = append(defs, `-D`, `GOPKGPATH="`+pkgpath+`"`)
 	}
 	compiler := envList("CC", cfg.DefaultCC(cfg.Goos, cfg.Goarch))
@@ -596,28 +598,23 @@ func gccgoPkgpath(p *load.Package) string {
 	return p.ImportPath
 }
 
-// gccgoCleanPkgpath returns the form of p's pkgpath that gccgo uses
-// for symbol names. This is like gccgoPkgpathToSymbolNew in cmd/cgo/out.go.
-func gccgoCleanPkgpath(p *load.Package) string {
-	ppath := gccgoPkgpath(p)
-	bsl := []byte{}
-	changed := false
-	for _, c := range []byte(ppath) {
-		switch {
-		case 'A' <= c && c <= 'Z', 'a' <= c && c <= 'z',
-			'0' <= c && c <= '9', c == '_':
-			bsl = append(bsl, c)
-		case c == '.':
-			bsl = append(bsl, ".x2e"...)
-			changed = true
-		default:
-			encbytes := []byte(fmt.Sprintf("..z%02x", c))
-			bsl = append(bsl, encbytes...)
-			changed = true
+var gccgoToSymbolFuncOnce sync.Once
+var gccgoToSymbolFunc func(string) string
+
+func (tools gccgoToolchain) gccgoCleanPkgpath(b *Builder, p *load.Package) string {
+	gccgoToSymbolFuncOnce.Do(func() {
+		if cfg.BuildN {
+			gccgoToSymbolFunc = func(s string) string { return s }
+			return
 		}
-	}
-	if !changed {
-		return ppath
-	}
-	return string(bsl)
+		fn, err := pkgpath.ToSymbolFunc(tools.compiler(), b.WorkDir)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "cmd/go: %v\n", err)
+			base.SetExitStatus(2)
+			base.Exit()
+		}
+		gccgoToSymbolFunc = fn
+	})
+
+	return gccgoToSymbolFunc(gccgoPkgpath(p))
 }
diff --git a/libgo/go/cmd/go/internal/work/security.go b/libgo/go/cmd/go/internal/work/security.go
index 3ee68ac..0d96282 100644
--- a/libgo/go/cmd/go/internal/work/security.go
+++ b/libgo/go/cmd/go/internal/work/security.go
@@ -42,8 +42,8 @@ import (
 var re = lazyregexp.New
 
 var validCompilerFlags = []*lazyregexp.Regexp{
-	re(`-D([A-Za-z_].*)`),
-	re(`-U([A-Za-z_]*)`),
+	re(`-D([A-Za-z_][A-Za-z0-9_]*)(=[^@\-]*)?`),
+	re(`-U([A-Za-z_][A-Za-z0-9_]*)`),
 	re(`-F([^@\-].*)`),
 	re(`-I([^@\-].*)`),
 	re(`-O`),
@@ -51,8 +51,8 @@ var validCompilerFlags = []*lazyregexp.Regexp{
 	re(`-W`),
 	re(`-W([^@,]+)`), // -Wall but not -Wa,-foo.
 	re(`-Wa,-mbig-obj`),
-	re(`-Wp,-D([A-Za-z_].*)`),
-	re(`-Wp,-U([A-Za-z_]*)`),
+	re(`-Wp,-D([A-Za-z_][A-Za-z0-9_]*)(=[^@,\-]*)?`),
+	re(`-Wp,-U([A-Za-z_][A-Za-z0-9_]*)`),
 	re(`-ansi`),
 	re(`-f(no-)?asynchronous-unwind-tables`),
 	re(`-f(no-)?blocks`),
diff --git a/libgo/go/cmd/go/internal/work/security_test.go b/libgo/go/cmd/go/internal/work/security_test.go
index 11e74f2..aec9789 100644
--- a/libgo/go/cmd/go/internal/work/security_test.go
+++ b/libgo/go/cmd/go/internal/work/security_test.go
@@ -13,6 +13,7 @@ var goodCompilerFlags = [][]string{
 	{"-DFOO"},
 	{"-Dfoo=bar"},
 	{"-Ufoo"},
+	{"-Ufoo1"},
 	{"-F/Qt"},
 	{"-I/"},
 	{"-I/etc/passwd"},
@@ -24,6 +25,8 @@ var goodCompilerFlags = [][]string{
 	{"-Wall"},
 	{"-Wp,-Dfoo=bar"},
 	{"-Wp,-Ufoo"},
+	{"-Wp,-Dfoo1"},
+	{"-Wp,-Ufoo1"},
 	{"-fobjc-arc"},
 	{"-fno-objc-arc"},
 	{"-fomit-frame-pointer"},
@@ -78,6 +81,8 @@ var badCompilerFlags = [][]string{
 	{"-O@1"},
 	{"-Wa,-foo"},
 	{"-W@foo"},
+	{"-Wp,-DX,-D@X"},
+	{"-Wp,-UX,-U@X"},
 	{"-g@gdb"},
 	{"-g-gdb"},
 	{"-march=@dawn"},
diff --git a/libgo/go/cmd/internal/pkgpath/pkgpath.go b/libgo/go/cmd/internal/pkgpath/pkgpath.go
new file mode 100644
index 0000000..40a040a
--- /dev/null
+++ b/libgo/go/cmd/internal/pkgpath/pkgpath.go
@@ -0,0 +1,174 @@
+// Copyright 2020 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 pkgpath determines the package path used by gccgo/GoLLVM symbols.
+// This package is not used for the gc compiler.
+package pkgpath
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+// ToSymbolFunc returns a function that may be used to convert a
+// package path into a string suitable for use as a symbol.
+// cmd is the gccgo/GoLLVM compiler in use, and tmpdir is a temporary
+// directory to pass to ioutil.TempFile.
+// For example, this returns a function that converts "net/http"
+// into a string like "net..z2fhttp". The actual string varies for
+// different gccgo/GoLLVM versions, which is why this returns a function
+// that does the conversion appropriate for the compiler in use.
+func ToSymbolFunc(cmd, tmpdir string) (func(string) string, error) {
+	// To determine the scheme used by cmd, we compile a small
+	// file and examine the assembly code. Older versions of gccgo
+	// use a simple mangling scheme where there can be collisions
+	// between packages whose paths are different but mangle to
+	// the same string. More recent versions use a new mangler
+	// that avoids these collisions.
+	const filepat = "*_gccgo_manglechck.go"
+	f, err := ioutil.TempFile(tmpdir, filepat)
+	if err != nil {
+		return nil, err
+	}
+	gofilename := f.Name()
+	f.Close()
+	defer os.Remove(gofilename)
+
+	if err := ioutil.WriteFile(gofilename, []byte(mangleCheckCode), 0644); err != nil {
+		return nil, err
+	}
+
+	command := exec.Command(cmd, "-S", "-o", "-", gofilename)
+	buf, err := command.Output()
+	if err != nil {
+		return nil, err
+	}
+
+	// Original mangling: go.l__ufer.Run
+	// Mangling v2: go.l..u00e4ufer.Run
+	// Mangling v3: go_0l_u00e4ufer.Run
+	if bytes.Contains(buf, []byte("go_0l_u00e4ufer.Run")) {
+		return toSymbolV3, nil
+	} else if bytes.Contains(buf, []byte("go.l..u00e4ufer.Run")) {
+		return toSymbolV2, nil
+	} else if bytes.Contains(buf, []byte("go.l__ufer.Run")) {
+		return toSymbolV1, nil
+	} else {
+		return nil, errors.New(cmd + ": unrecognized mangling scheme")
+	}
+}
+
+// mangleCheckCode is the package we compile to determine the mangling scheme.
+const mangleCheckCode = `
+package läufer
+func Run(x int) int {
+  return 1
+}
+`
+
+// toSymbolV1 converts a package path using the original mangling scheme.
+func toSymbolV1(ppath string) string {
+	clean := func(r rune) rune {
+		switch {
+		case 'A' <= r && r <= 'Z', 'a' <= r && r <= 'z',
+			'0' <= r && r <= '9':
+			return r
+		}
+		return '_'
+	}
+	return strings.Map(clean, ppath)
+}
+
+// toSymbolV2 converts a package path using the second mangling scheme.
+func toSymbolV2(ppath string) string {
+	// This has to build at boostrap time, so it has to build
+	// with Go 1.4, so we don't use strings.Builder.
+	bsl := make([]byte, 0, len(ppath))
+	changed := false
+	for _, c := range ppath {
+		if ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z') || ('0' <= c && c <= '9') || c == '_' {
+			bsl = append(bsl, byte(c))
+			continue
+		}
+		var enc string
+		switch {
+		case c == '.':
+			enc = ".x2e"
+		case c < 0x80:
+			enc = fmt.Sprintf("..z%02x", c)
+		case c < 0x10000:
+			enc = fmt.Sprintf("..u%04x", c)
+		default:
+			enc = fmt.Sprintf("..U%08x", c)
+		}
+		bsl = append(bsl, enc...)
+		changed = true
+	}
+	if !changed {
+		return ppath
+	}
+	return string(bsl)
+}
+
+// v3UnderscoreCodes maps from a character that supports an underscore
+// encoding to the underscore encoding character.
+var v3UnderscoreCodes = map[byte]byte{
+	'_': '_',
+	'.': '0',
+	'/': '1',
+	'*': '2',
+	',': '3',
+	'{': '4',
+	'}': '5',
+	'[': '6',
+	']': '7',
+	'(': '8',
+	')': '9',
+	'"': 'a',
+	' ': 'b',
+	';': 'c',
+}
+
+// toSymbolV3 converts a package path using the third mangling scheme.
+func toSymbolV3(ppath string) string {
+	// This has to build at boostrap time, so it has to build
+	// with Go 1.4, so we don't use strings.Builder.
+	bsl := make([]byte, 0, len(ppath))
+	changed := false
+	for _, c := range ppath {
+		if ('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z') || ('0' <= c && c <= '9') {
+			bsl = append(bsl, byte(c))
+			continue
+		}
+
+		if c < 0x80 {
+			if u, ok := v3UnderscoreCodes[byte(c)]; ok {
+				bsl = append(bsl, '_', u)
+				changed = true
+				continue
+			}
+		}
+
+		var enc string
+		switch {
+		case c < 0x80:
+			enc = fmt.Sprintf("_x%02x", c)
+		case c < 0x10000:
+			enc = fmt.Sprintf("_u%04x", c)
+		default:
+			enc = fmt.Sprintf("_U%08x", c)
+		}
+		bsl = append(bsl, enc...)
+		changed = true
+	}
+	if !changed {
+		return ppath
+	}
+	return string(bsl)
+}
diff --git a/libgo/go/cmd/internal/pkgpath/pkgpath_test.go b/libgo/go/cmd/internal/pkgpath/pkgpath_test.go
new file mode 100644
index 0000000..232e803
--- /dev/null
+++ b/libgo/go/cmd/internal/pkgpath/pkgpath_test.go
@@ -0,0 +1,141 @@
+// Copyright 2020 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 pkgpath
+
+import (
+	"os"
+	"testing"
+)
+
+const testEnvName = "GO_PKGPATH_TEST_COMPILER"
+
+// This init function supports TestToSymbolFunc. For simplicity,
+// we use the test binary itself as a sample gccgo driver.
+// We set an environment variable to specify how it should behave.
+func init() {
+	switch os.Getenv(testEnvName) {
+	case "":
+		return
+	case "v1":
+		os.Stdout.WriteString(`.string	"go.l__ufer.Run"`)
+		os.Exit(0)
+	case "v2":
+		os.Stdout.WriteString(`.string	"go.l..u00e4ufer.Run"`)
+		os.Exit(0)
+	case "v3":
+		os.Stdout.WriteString(`.string	"go_0l_u00e4ufer.Run"`)
+		os.Exit(0)
+	case "error":
+		os.Stdout.WriteString(`unknown string`)
+		os.Exit(0)
+	}
+}
+
+func TestToSymbolFunc(t *testing.T) {
+	const input = "pä世🜃"
+	tests := []struct {
+		env     string
+		fail    bool
+		mangled string
+	}{
+		{
+			env:     "v1",
+			mangled: "p___",
+		},
+		{
+			env:     "v2",
+			mangled: "p..u00e4..u4e16..U0001f703",
+		},
+		{
+			env:     "v3",
+			mangled: "p_u00e4_u4e16_U0001f703",
+		},
+		{
+			env:  "error",
+			fail: true,
+		},
+	}
+
+	cmd := os.Args[0]
+	tmpdir := t.TempDir()
+
+	defer os.Unsetenv(testEnvName)
+
+	for _, test := range tests {
+		t.Run(test.env, func(t *testing.T) {
+			os.Setenv(testEnvName, test.env)
+
+			fn, err := ToSymbolFunc(cmd, tmpdir)
+			if err != nil {
+				if !test.fail {
+					t.Errorf("ToSymbolFunc(%q, %q): unexpected error %v", cmd, tmpdir, err)
+				}
+			} else if test.fail {
+				t.Errorf("ToSymbolFunc(%q, %q) succeeded but expected to fail", cmd, tmpdir)
+			} else if got, want := fn(input), test.mangled; got != want {
+				t.Errorf("ToSymbolFunc(%q, %q)(%q) = %q, want %q", cmd, tmpdir, input, got, want)
+			}
+		})
+	}
+}
+
+var symbolTests = []struct {
+	input, v1, v2, v3 string
+}{
+	{
+		"",
+		"",
+		"",
+		"",
+	},
+	{
+		"bytes",
+		"bytes",
+		"bytes",
+		"bytes",
+	},
+	{
+		"net/http",
+		"net_http",
+		"net..z2fhttp",
+		"net_1http",
+	},
+	{
+		"golang.org/x/net/http",
+		"golang_org_x_net_http",
+		"golang.x2eorg..z2fx..z2fnet..z2fhttp",
+		"golang_0org_1x_1net_1http",
+	},
+	{
+		"pä世.🜃",
+		"p____",
+		"p..u00e4..u4e16.x2e..U0001f703",
+		"p_u00e4_u4e16_0_U0001f703",
+	},
+}
+
+func TestV1(t *testing.T) {
+	for _, test := range symbolTests {
+		if got, want := toSymbolV1(test.input), test.v1; got != want {
+			t.Errorf("toSymbolV1(%q) = %q, want %q", test.input, got, want)
+		}
+	}
+}
+
+func TestV2(t *testing.T) {
+	for _, test := range symbolTests {
+		if got, want := toSymbolV2(test.input), test.v2; got != want {
+			t.Errorf("toSymbolV2(%q) = %q, want %q", test.input, got, want)
+		}
+	}
+}
+
+func TestV3(t *testing.T) {
+	for _, test := range symbolTests {
+		if got, want := toSymbolV3(test.input), test.v3; got != want {
+			t.Errorf("toSymbolV3(%q) = %q, want %q", test.input, got, want)
+		}
+	}
+}
diff --git a/libgo/go/go/internal/srcimporter/srcimporter.go b/libgo/go/go/internal/srcimporter/srcimporter.go
index 90bb3a9..3a2ca9a 100644
--- a/libgo/go/go/internal/srcimporter/srcimporter.go
+++ b/libgo/go/go/internal/srcimporter/srcimporter.go
@@ -262,5 +262,5 @@ func (p *Importer) joinPath(elem ...string) string {
 	return filepath.Join(elem...)
 }
 
-//go:linkname setUsesCgo go/types.srcimporter_setUsesCgo
+//go:linkname setUsesCgo go_1types.srcimporter__setUsesCgo
 func setUsesCgo(conf *types.Config)
diff --git a/libgo/go/internal/bytealg/bytealg.c b/libgo/go/internal/bytealg/bytealg.c
index 969732d..6c08340 100644
--- a/libgo/go/internal/bytealg/bytealg.c
+++ b/libgo/go/internal/bytealg/bytealg.c
@@ -38,7 +38,7 @@ static const void *goMemmem(const void *in, size_t inl, const void *s, size_t sl
 #endif
 
 intgo Compare(struct __go_open_array, struct __go_open_array)
-  __asm__(GOSYM_PREFIX "internal..z2fbytealg.Compare")
+  __asm__(GOSYM_PREFIX "internal_1bytealg.Compare")
   __attribute__((no_split_stack));
 
 intgo Compare(struct __go_open_array a, struct __go_open_array b)
@@ -69,7 +69,7 @@ intgo Compare(struct __go_open_array a, struct __go_open_array b)
 }
 
 intgo IndexByte(struct __go_open_array, byte)
-  __asm__(GOSYM_PREFIX "internal..z2fbytealg.IndexByte")
+  __asm__(GOSYM_PREFIX "internal_1bytealg.IndexByte")
   __attribute__((no_split_stack));
 
 intgo IndexByte(struct __go_open_array b, byte c)
@@ -85,7 +85,7 @@ intgo IndexByte(struct __go_open_array b, byte c)
 
 
 intgo IndexByteString(String, byte)
-  __asm__(GOSYM_PREFIX "internal..z2fbytealg.IndexByteString")
+  __asm__(GOSYM_PREFIX "internal_1bytealg.IndexByteString")
   __attribute__((no_split_stack));
 
 intgo IndexByteString(String s, byte c)
@@ -100,7 +100,7 @@ intgo IndexByteString(String s, byte c)
 }
 
 intgo Index(struct __go_open_array, struct __go_open_array)
-  __asm__(GOSYM_PREFIX "internal..z2fbytealg.Index")
+  __asm__(GOSYM_PREFIX "internal_1bytealg.Index")
   __attribute__((no_split_stack));
 
 intgo Index(struct __go_open_array a, struct __go_open_array b)
@@ -115,7 +115,7 @@ intgo Index(struct __go_open_array a, struct __go_open_array b)
 }
 
 intgo IndexString(String, String)
-  __asm__(GOSYM_PREFIX "internal..z2fbytealg.IndexString")
+  __asm__(GOSYM_PREFIX "internal_1bytealg.IndexString")
   __attribute__((no_split_stack));
 
 intgo IndexString(String a, String b)
diff --git a/libgo/go/internal/cpu/cpu_gccgo.c b/libgo/go/internal/cpu/cpu_gccgo.c
index 6b40f01..da26f4d 100644
--- a/libgo/go/internal/cpu/cpu_gccgo.c
+++ b/libgo/go/internal/cpu/cpu_gccgo.c
@@ -21,7 +21,7 @@ struct cpuid_ret {
 };
 
 struct cpuid_ret cpuid(uint32_t, uint32_t)
-  __asm__(GOSYM_PREFIX "internal..z2fcpu.cpuid")
+  __asm__(GOSYM_PREFIX "internal_1cpu.cpuid")
   __attribute__((no_split_stack));
 
 struct cpuid_ret cpuid(uint32_t eaxArg, uint32_t ecxArg) {
@@ -45,7 +45,7 @@ struct xgetbv_ret {
 };
 
 struct xgetbv_ret xgetbv(void)
-  __asm__(GOSYM_PREFIX "internal..z2fcpu.xgetbv")
+  __asm__(GOSYM_PREFIX "internal_1cpu.xgetbv")
   __attribute__((no_split_stack));
 
 #pragma GCC push_options
@@ -82,7 +82,7 @@ struct queryResult {
 };
 
 struct facilityList stfle(void)
-  __asm__(GOSYM_PREFIX "internal..z2fcpu.stfle")
+  __asm__(GOSYM_PREFIX "internal_1cpu.stfle")
   __attribute__((no_split_stack));
 
 struct facilityList stfle(void) {
@@ -96,7 +96,7 @@ struct facilityList stfle(void) {
 }
 
 struct queryResult kmQuery(void)
-  __asm__(GOSYM_PREFIX "internal..z2fcpu.kmQuery")
+  __asm__(GOSYM_PREFIX "internal_1cpu.kmQuery")
   __attribute__((no_split_stack));
 
 struct queryResult kmQuery() {
@@ -110,7 +110,7 @@ struct queryResult kmQuery() {
 }
 
 struct queryResult kmcQuery(void)
-  __asm__(GOSYM_PREFIX "internal..z2fcpu.kmcQuery")
+  __asm__(GOSYM_PREFIX "internal_1cpu.kmcQuery")
   __attribute__((no_split_stack));
 
 struct queryResult kmcQuery() {
@@ -125,7 +125,7 @@ struct queryResult kmcQuery() {
 }
 
 struct queryResult kmctrQuery(void)
-  __asm__(GOSYM_PREFIX "internal..z2fcpu.kmctrQuery")
+  __asm__(GOSYM_PREFIX "internal_1cpu.kmctrQuery")
   __attribute__((no_split_stack));
 
 struct queryResult kmctrQuery() {
@@ -140,7 +140,7 @@ struct queryResult kmctrQuery() {
 }
 
 struct queryResult kmaQuery(void)
-  __asm__(GOSYM_PREFIX "internal..z2fcpu.kmaQuery")
+  __asm__(GOSYM_PREFIX "internal_1cpu.kmaQuery")
   __attribute__((no_split_stack));
 
 struct queryResult kmaQuery() {
@@ -155,7 +155,7 @@ struct queryResult kmaQuery() {
 }
 
 struct queryResult kimdQuery(void)
-  __asm__(GOSYM_PREFIX "internal..z2fcpu.kimdQuery")
+  __asm__(GOSYM_PREFIX "internal_1cpu.kimdQuery")
   __attribute__((no_split_stack));
 
 struct queryResult kimdQuery() {
@@ -170,7 +170,7 @@ struct queryResult kimdQuery() {
 }
 
 struct queryResult klmdQuery(void)
-  __asm__(GOSYM_PREFIX "internal..z2fcpu.klmdQuery")
+  __asm__(GOSYM_PREFIX "internal_1cpu.klmdQuery")
   __attribute__((no_split_stack));
 
 struct queryResult klmdQuery() {
@@ -185,7 +185,7 @@ struct queryResult klmdQuery() {
 }
 
 struct queryResult kdsaQuery(void)
-  __asm__(GOSYM_PREFIX "internal..z2fcpu.kdsaQuery")
+  __asm__(GOSYM_PREFIX "internal_1cpu.kdsaQuery")
   __attribute__((no_split_stack));
 
 struct queryResult kdsaQuery() {
diff --git a/libgo/go/internal/cpu/cpu_mips64x.go b/libgo/go/internal/cpu/cpu_mips64x.go
index 0c4794a..af10a50 100644
--- a/libgo/go/internal/cpu/cpu_mips64x.go
+++ b/libgo/go/internal/cpu/cpu_mips64x.go
@@ -6,8 +6,6 @@
 
 package cpu
 
-const CacheLinePadSize = 32
-
 // This is initialized by archauxv and should not be changed after it is
 // initialized.
 var HWCap uint
diff --git a/libgo/go/log/syslog/syslog_c.c b/libgo/go/log/syslog/syslog_c.c
index 36e7694..acfee6e 100644
--- a/libgo/go/log/syslog/syslog_c.c
+++ b/libgo/go/log/syslog/syslog_c.c
@@ -12,7 +12,7 @@
    can't represent a C varargs function in Go.  */
 
 void syslog_c(intgo, const char*)
-  __asm__ (GOSYM_PREFIX "log..z2fsyslog.syslog_c");
+  __asm__ (GOSYM_PREFIX "log_1syslog.syslog__c");
 
 void
 syslog_c (intgo priority, const char *msg)
diff --git a/libgo/go/math/big/nat.go b/libgo/go/math/big/nat.go
index 6a3989b..8c43de6 100644
--- a/libgo/go/math/big/nat.go
+++ b/libgo/go/math/big/nat.go
@@ -928,7 +928,7 @@ func (z nat) divRecursiveStep(u, v nat, depth int, tmp *nat, temps []*nat) {
 
 	// Now u < (v<<B), compute lower bits in the same way.
 	// Choose shift = B-1 again.
-	s := B
+	s := B - 1
 	qhat := *temps[depth]
 	qhat.clear()
 	qhat.divRecursiveStep(u[s:].norm(), v[s:], depth+1, tmp, temps)
diff --git a/libgo/go/runtime/atomic_pointer.go b/libgo/go/runtime/atomic_pointer.go
index 49b0f2b..0295913 100644
--- a/libgo/go/runtime/atomic_pointer.go
+++ b/libgo/go/runtime/atomic_pointer.go
@@ -39,10 +39,10 @@ func atomicstorep(ptr unsafe.Pointer, new unsafe.Pointer) {
 // We cannot just call the runtime routines, because the race detector expects
 // to be able to intercept the sync/atomic forms but not the runtime forms.
 
-//go:linkname sync_atomic_StoreUintptr sync..z2fatomic.StoreUintptr
+//go:linkname sync_atomic_StoreUintptr sync_1atomic.StoreUintptr
 func sync_atomic_StoreUintptr(ptr *uintptr, new uintptr)
 
-//go:linkname sync_atomic_StorePointer sync..z2fatomic.StorePointer
+//go:linkname sync_atomic_StorePointer sync_1atomic.StorePointer
 //go:nosplit
 func sync_atomic_StorePointer(ptr *unsafe.Pointer, new unsafe.Pointer) {
 	if writeBarrier.enabled {
@@ -51,10 +51,10 @@ func sync_atomic_StorePointer(ptr *unsafe.Pointer, new unsafe.Pointer) {
 	sync_atomic_StoreUintptr((*uintptr)(unsafe.Pointer(ptr)), uintptr(new))
 }
 
-//go:linkname sync_atomic_SwapUintptr sync..z2fatomic.SwapUintptr
+//go:linkname sync_atomic_SwapUintptr sync_1atomic.SwapUintptr
 func sync_atomic_SwapUintptr(ptr *uintptr, new uintptr) uintptr
 
-//go:linkname sync_atomic_SwapPointer sync..z2fatomic.SwapPointer
+//go:linkname sync_atomic_SwapPointer sync_1atomic.SwapPointer
 //go:nosplit
 func sync_atomic_SwapPointer(ptr *unsafe.Pointer, new unsafe.Pointer) unsafe.Pointer {
 	if writeBarrier.enabled {
@@ -64,10 +64,10 @@ func sync_atomic_SwapPointer(ptr *unsafe.Pointer, new unsafe.Pointer) unsafe.Poi
 	return old
 }
 
-//go:linkname sync_atomic_CompareAndSwapUintptr sync..z2fatomic.CompareAndSwapUintptr
+//go:linkname sync_atomic_CompareAndSwapUintptr sync_1atomic.CompareAndSwapUintptr
 func sync_atomic_CompareAndSwapUintptr(ptr *uintptr, old, new uintptr) bool
 
-//go:linkname sync_atomic_CompareAndSwapPointer sync..z2fatomic.CompareAndSwapPointer
+//go:linkname sync_atomic_CompareAndSwapPointer sync_1atomic.CompareAndSwapPointer
 //go:nosplit
 func sync_atomic_CompareAndSwapPointer(ptr *unsafe.Pointer, old, new unsafe.Pointer) bool {
 	if writeBarrier.enabled {
diff --git a/libgo/go/runtime/chan.go b/libgo/go/runtime/chan.go
index b909d47..8e104f1 100644
--- a/libgo/go/runtime/chan.go
+++ b/libgo/go/runtime/chan.go
@@ -774,7 +774,7 @@ func reflect_chanlen(c *hchan) int {
 	return int(c.qcount)
 }
 
-//go:linkname reflectlite_chanlen internal..z2freflectlite.chanlen
+//go:linkname reflectlite_chanlen internal_1reflectlite.chanlen
 func reflectlite_chanlen(c *hchan) int {
 	if c == nil {
 		return 0
diff --git a/libgo/go/runtime/cpuprof.go b/libgo/go/runtime/cpuprof.go
index d395210..43f0a67 100644
--- a/libgo/go/runtime/cpuprof.go
+++ b/libgo/go/runtime/cpuprof.go
@@ -189,7 +189,7 @@ func CPUProfile() []byte {
 	panic("CPUProfile no longer available")
 }
 
-//go:linkname runtime_pprof_runtime_cyclesPerSecond runtime..z2fpprof.runtime_cyclesPerSecond
+//go:linkname runtime_pprof_runtime_cyclesPerSecond runtime_1pprof.runtime__cyclesPerSecond
 func runtime_pprof_runtime_cyclesPerSecond() int64 {
 	return tickspersecond()
 }
@@ -200,7 +200,7 @@ func runtime_pprof_runtime_cyclesPerSecond() int64 {
 // on has been returned, readProfile returns eof=true.
 // The caller must save the returned data and tags before calling readProfile again.
 //
-//go:linkname runtime_pprof_readProfile runtime..z2fpprof.readProfile
+//go:linkname runtime_pprof_readProfile runtime_1pprof.readProfile
 func runtime_pprof_readProfile() ([]uint64, []unsafe.Pointer, bool) {
 	lock(&cpuprof.lock)
 	log := cpuprof.log
diff --git a/libgo/go/runtime/debug.go b/libgo/go/runtime/debug.go
index 1202e36..ff76580 100644
--- a/libgo/go/runtime/debug.go
+++ b/libgo/go/runtime/debug.go
@@ -66,7 +66,7 @@ func NumGoroutine() int {
 // added.
 func Fieldtrack(map[string]bool)
 
-//go:linkname debug_modinfo runtime..z2fdebug.modinfo
+//go:linkname debug_modinfo runtime_1debug.modinfo
 func debug_modinfo() string {
 	return modinfo
 }
diff --git a/libgo/go/runtime/heapdump.go b/libgo/go/runtime/heapdump.go
index e8f16e9..816d93c 100644
--- a/libgo/go/runtime/heapdump.go
+++ b/libgo/go/runtime/heapdump.go
@@ -16,7 +16,7 @@ import (
 	"unsafe"
 )
 
-//go:linkname runtime_debug_WriteHeapDump runtime..z2fdebug.WriteHeapDump
+//go:linkname runtime_debug_WriteHeapDump runtime_1debug.WriteHeapDump
 func runtime_debug_WriteHeapDump(fd uintptr) {
 	stopTheWorld("write heap dump")
 
diff --git a/libgo/go/runtime/iface.go b/libgo/go/runtime/iface.go
index 5667ddb..f9df1e0 100644
--- a/libgo/go/runtime/iface.go
+++ b/libgo/go/runtime/iface.go
@@ -505,7 +505,7 @@ func reflect_ifaceE2I(inter *interfacetype, e eface, dst *iface) {
 	dst.data = e.data
 }
 
-//go:linkname reflectlite_ifaceE2I internal..z2freflectlite.ifaceE2I
+//go:linkname reflectlite_ifaceE2I internal_1reflectlite.ifaceE2I
 func reflectlite_ifaceE2I(inter *interfacetype, e eface, dst *iface) {
 	t := e._type
 	if t == nil {
diff --git a/libgo/go/runtime/internal/atomic/atomic.c b/libgo/go/runtime/internal/atomic/atomic.c
index 8ae4d7b..9fed1a8 100644
--- a/libgo/go/runtime/internal/atomic/atomic.c
+++ b/libgo/go/runtime/internal/atomic/atomic.c
@@ -7,7 +7,7 @@
 #include "runtime.h"
 
 uint32_t Load (uint32_t *ptr)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Load")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Load")
   __attribute__ ((no_split_stack));
 
 uint32_t
@@ -17,7 +17,7 @@ Load (uint32_t *ptr)
 }
 
 void *Loadp (void *ptr)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Loadp")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Loadp")
   __attribute__ ((no_split_stack));
 
 void *
@@ -27,7 +27,7 @@ Loadp (void *ptr)
 }
 
 uint8_t Load8 (uint8_t *ptr)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Load8")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Load8")
   __attribute__ ((no_split_stack));
 
 uint8_t
@@ -37,7 +37,7 @@ Load8 (uint8_t *ptr)
 }
 
 uint64_t Load64 (uint64_t *ptr)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Load64")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Load64")
   __attribute__ ((no_split_stack));
 
 uint64_t
@@ -49,7 +49,7 @@ Load64 (uint64_t *ptr)
 }
 
 uint32_t LoadAcq (uint32_t *ptr)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.LoadAcq")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.LoadAcq")
   __attribute__ ((no_split_stack));
 
 uint32_t
@@ -59,7 +59,7 @@ LoadAcq (uint32_t *ptr)
 }
 
 uintptr_t Loaduintptr (uintptr_t *ptr)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Loaduintptr")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Loaduintptr")
   __attribute__ ((no_split_stack));
 
 uintptr_t
@@ -69,7 +69,7 @@ Loaduintptr (uintptr_t *ptr)
 }
 
 uintgo Loaduint (uintgo *ptr)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Loaduint")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Loaduint")
   __attribute__ ((no_split_stack));
 
 uintgo
@@ -79,7 +79,7 @@ Loaduint (uintgo *ptr)
 }
 
 int64_t Loadint64 (int64_t *ptr)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Loadint64")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Loadint64")
   __attribute__ ((no_split_stack));
 
 int64_t
@@ -91,7 +91,7 @@ Loadint64 (int64_t *ptr)
 }
 
 uint32_t Xadd (uint32_t *ptr, int32_t delta)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xadd")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Xadd")
   __attribute__ ((no_split_stack));
 
 uint32_t
@@ -101,7 +101,7 @@ Xadd (uint32_t *ptr, int32_t delta)
 }
 
 uint64_t Xadd64 (uint64_t *ptr, int64_t delta)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xadd64")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Xadd64")
   __attribute__ ((no_split_stack));
 
 uint64_t
@@ -113,7 +113,7 @@ Xadd64 (uint64_t *ptr, int64_t delta)
 }
 
 uintptr_t Xadduintptr (uintptr_t *ptr, uintptr_t delta)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xadduintptr")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Xadduintptr")
   __attribute__ ((no_split_stack));
 
 uintptr_t
@@ -123,7 +123,7 @@ Xadduintptr (uintptr_t *ptr, uintptr_t delta)
 }
 
 int64_t Xaddint64 (int64_t *ptr, int64_t delta)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xaddint64")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Xaddint64")
   __attribute__ ((no_split_stack));
 
 int64_t
@@ -135,7 +135,7 @@ Xaddint64 (int64_t *ptr, int64_t delta)
 }
 
 uint32_t Xchg (uint32_t *ptr, uint32_t new)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xchg")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Xchg")
   __attribute__ ((no_split_stack));
 
 uint32_t
@@ -145,7 +145,7 @@ Xchg (uint32_t *ptr, uint32_t new)
 }
 
 uint64_t Xchg64 (uint64_t *ptr, uint64_t new)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xchg64")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Xchg64")
   __attribute__ ((no_split_stack));
 
 uint64_t
@@ -157,7 +157,7 @@ Xchg64 (uint64_t *ptr, uint64_t new)
 }
 
 uintptr_t Xchguintptr (uintptr_t *ptr, uintptr_t new)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Xchguintptr")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Xchguintptr")
   __attribute__ ((no_split_stack));
 
 uintptr_t
@@ -167,7 +167,7 @@ Xchguintptr (uintptr_t *ptr, uintptr_t new)
 }
 
 void And8 (uint8_t *ptr, uint8_t val)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.And8")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.And8")
   __attribute__ ((no_split_stack));
 
 void
@@ -177,7 +177,7 @@ And8 (uint8_t *ptr, uint8_t val)
 }
 
 void Or8 (uint8_t *ptr, uint8_t val)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Or8")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Or8")
   __attribute__ ((no_split_stack));
 
 void
@@ -187,7 +187,7 @@ Or8 (uint8_t *ptr, uint8_t val)
 }
 
 _Bool Cas (uint32_t *ptr, uint32_t old, uint32_t new)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Cas")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Cas")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -197,7 +197,7 @@ Cas (uint32_t *ptr, uint32_t old, uint32_t new)
 }
 
 _Bool Cas64 (uint64_t *ptr, uint64_t old, uint64_t new)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Cas64")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Cas64")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -209,7 +209,7 @@ Cas64 (uint64_t *ptr, uint64_t old, uint64_t new)
 }
 
 _Bool CasRel (uint32_t *ptr, uint32_t old, uint32_t new)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.CasRel")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.CasRel")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -219,7 +219,7 @@ CasRel (uint32_t *ptr, uint32_t old, uint32_t new)
 }
 
 _Bool Casp1 (void **ptr, void *old, void *new)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Casp1")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Casp1")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -229,7 +229,7 @@ Casp1 (void **ptr, void *old, void *new)
 }
 
 _Bool Casuintptr (uintptr_t *ptr, uintptr_t old, uintptr_t new)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Casuintptr")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Casuintptr")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -239,7 +239,7 @@ Casuintptr (uintptr_t *ptr, uintptr_t old, uintptr_t new)
 }
 
 void Store (uint32_t *ptr, uint32_t val)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Store")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Store")
   __attribute__ ((no_split_stack));
 
 void
@@ -249,7 +249,7 @@ Store (uint32_t *ptr, uint32_t val)
 }
 
 void Store8 (uint8_t *ptr, uint8_t val)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Store8")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Store8")
   __attribute__ ((no_split_stack));
 
 void
@@ -259,7 +259,7 @@ Store8 (uint8_t *ptr, uint8_t val)
 }
 
 void Store64 (uint64_t *ptr, uint64_t val)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Store64")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Store64")
   __attribute__ ((no_split_stack));
 
 void
@@ -271,7 +271,7 @@ Store64 (uint64_t *ptr, uint64_t val)
 }
 
 void StoreRel (uint32_t *ptr, uint32_t val)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.StoreRel")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.StoreRel")
   __attribute__ ((no_split_stack));
 
 void
@@ -281,7 +281,7 @@ StoreRel (uint32_t *ptr, uint32_t val)
 }
 
 void Storeuintptr (uintptr_t *ptr, uintptr_t val)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.Storeuintptr")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.Storeuintptr")
   __attribute__ ((no_split_stack));
 
 void
@@ -291,7 +291,7 @@ Storeuintptr (uintptr_t *ptr, uintptr_t val)
 }
 
 void StorepNoWB (void *ptr, void *val)
-  __asm__ (GOSYM_PREFIX "runtime..z2finternal..z2fatomic.StorepNoWB")
+  __asm__ (GOSYM_PREFIX "runtime_1internal_1atomic.StorepNoWB")
   __attribute__ ((no_split_stack));
 
 void
diff --git a/libgo/go/runtime/malloc.go b/libgo/go/runtime/malloc.go
index 81351ee..feb043a 100644
--- a/libgo/go/runtime/malloc.go
+++ b/libgo/go/runtime/malloc.go
@@ -1220,12 +1220,12 @@ func newobject(typ *_type) unsafe.Pointer {
 	return mallocgc(typ.size, typ, true)
 }
 
-//go:linkname reflect_unsafe_New reflect.unsafe_New
+//go:linkname reflect_unsafe_New reflect.unsafe__New
 func reflect_unsafe_New(typ *_type) unsafe.Pointer {
 	return mallocgc(typ.size, typ, true)
 }
 
-//go:linkname reflectlite_unsafe_New internal..z2freflectlite.unsafe_New
+//go:linkname reflectlite_unsafe_New internal_1reflectlite.unsafe__New
 func reflectlite_unsafe_New(typ *_type) unsafe.Pointer {
 	return mallocgc(typ.size, typ, true)
 }
@@ -1242,7 +1242,7 @@ func newarray(typ *_type, n int) unsafe.Pointer {
 	return mallocgc(mem, typ, true)
 }
 
-//go:linkname reflect_unsafe_NewArray reflect.unsafe_NewArray
+//go:linkname reflect_unsafe_NewArray reflect.unsafe__NewArray
 func reflect_unsafe_NewArray(typ *_type, n int) unsafe.Pointer {
 	return newarray(typ, n)
 }
diff --git a/libgo/go/runtime/map.go b/libgo/go/runtime/map.go
index b829771..1155fee 100644
--- a/libgo/go/runtime/map.go
+++ b/libgo/go/runtime/map.go
@@ -1417,7 +1417,7 @@ func reflect_maplen(h *hmap) int {
 	return h.count
 }
 
-//go:linkname reflectlite_maplen internal..z2freflectlite.maplen
+//go:linkname reflectlite_maplen internal_1reflectlite.maplen
 func reflectlite_maplen(h *hmap) int {
 	if h == nil {
 		return 0
diff --git a/libgo/go/runtime/mbarrier.go b/libgo/go/runtime/mbarrier.go
index 836f85a..3bd8b34 100644
--- a/libgo/go/runtime/mbarrier.go
+++ b/libgo/go/runtime/mbarrier.go
@@ -192,7 +192,7 @@ func reflect_typedmemmove(typ *_type, dst, src unsafe.Pointer) {
 	typedmemmove(typ, dst, src)
 }
 
-//go:linkname reflectlite_typedmemmove internal..z2freflectlite.typedmemmove
+//go:linkname reflectlite_typedmemmove internal_1reflectlite.typedmemmove
 func reflectlite_typedmemmove(typ *_type, dst, src unsafe.Pointer) {
 	reflect_typedmemmove(typ, dst, src)
 }
diff --git a/libgo/go/runtime/mgc.go b/libgo/go/runtime/mgc.go
index 9dd7bff..72479c2 100644
--- a/libgo/go/runtime/mgc.go
+++ b/libgo/go/runtime/mgc.go
@@ -223,7 +223,7 @@ func gcenable() {
 	memstats.enablegc = true // now that runtime is initialized, GC is okay
 }
 
-//go:linkname setGCPercent runtime..z2fdebug.setGCPercent
+//go:linkname setGCPercent runtime_1debug.setGCPercent
 func setGCPercent(in int32) (out int32) {
 	// Run on the system stack since we grab the heap lock.
 	systemstack(func() {
@@ -2238,7 +2238,7 @@ func gcResetMarkState() {
 
 var poolcleanup func()
 
-//go:linkname sync_runtime_registerPoolCleanup sync.runtime_registerPoolCleanup
+//go:linkname sync_runtime_registerPoolCleanup sync.runtime__registerPoolCleanup
 func sync_runtime_registerPoolCleanup(f func()) {
 	poolcleanup = f
 }
diff --git a/libgo/go/runtime/mheap.go b/libgo/go/runtime/mheap.go
index e73ee32..755efd1 100644
--- a/libgo/go/runtime/mheap.go
+++ b/libgo/go/runtime/mheap.go
@@ -1502,7 +1502,7 @@ func (h *mheap) scavengeAll() {
 	}
 }
 
-//go:linkname runtime_debug_freeOSMemory runtime..z2fdebug.freeOSMemory
+//go:linkname runtime_debug_freeOSMemory runtime_1debug.freeOSMemory
 func runtime_debug_freeOSMemory() {
 	GC()
 	systemstack(func() { mheap_.scavengeAll() })
diff --git a/libgo/go/runtime/mprof.go b/libgo/go/runtime/mprof.go
index a4b135d..afacf8f 100644
--- a/libgo/go/runtime/mprof.go
+++ b/libgo/go/runtime/mprof.go
@@ -942,7 +942,7 @@ func ThreadCreateProfile(p []StackRecord) (n int, ok bool) {
 	return
 }
 
-//go:linkname runtime_goroutineProfileWithLabels runtime..z2fpprof.runtime_goroutineProfileWithLabels
+//go:linkname runtime_goroutineProfileWithLabels runtime_1pprof.runtime__goroutineProfileWithLabels
 func runtime_goroutineProfileWithLabels(p []StackRecord, labels []unsafe.Pointer) (n int, ok bool) {
 	return goroutineProfileWithLabels(p, labels)
 }
diff --git a/libgo/go/runtime/mstats.go b/libgo/go/runtime/mstats.go
index 4e2c66ce..85a0861 100644
--- a/libgo/go/runtime/mstats.go
+++ b/libgo/go/runtime/mstats.go
@@ -468,7 +468,7 @@ func readmemstats_m(stats *MemStats) {
 	stats.StackSys += stats.StackInuse
 }
 
-//go:linkname readGCStats runtime..z2fdebug.readGCStats
+//go:linkname readGCStats runtime_1debug.readGCStats
 func readGCStats(pauses *[]uint64) {
 	systemstack(func() {
 		readGCStats_m(pauses)
diff --git a/libgo/go/runtime/net_plan9.go b/libgo/go/runtime/net_plan9.go
index 907c319..38ff5a4 100644
--- a/libgo/go/runtime/net_plan9.go
+++ b/libgo/go/runtime/net_plan9.go
@@ -8,12 +8,12 @@ import (
 	_ "unsafe"
 )
 
-//go:linkname runtime_ignoreHangup internal..z2fpoll.runtime_ignoreHangup
+//go:linkname runtime_ignoreHangup internal_1poll.runtime__ignoreHangup
 func runtime_ignoreHangup() {
 	getg().m.ignoreHangup = true
 }
 
-//go:linkname runtime_unignoreHangup internal..z2fpoll.runtime_unignoreHangup
+//go:linkname runtime_unignoreHangup internal_1poll.runtime__unignoreHangup
 func runtime_unignoreHangup(sig string) {
 	getg().m.ignoreHangup = false
 }
diff --git a/libgo/go/runtime/netpoll.go b/libgo/go/runtime/netpoll.go
index 72a136d..da00b57 100644
--- a/libgo/go/runtime/netpoll.go
+++ b/libgo/go/runtime/netpoll.go
@@ -113,7 +113,7 @@ var (
 	netpollWaiters uint32
 )
 
-//go:linkname poll_runtime_pollServerInit internal..z2fpoll.runtime_pollServerInit
+//go:linkname poll_runtime_pollServerInit internal_1poll.runtime__pollServerInit
 func poll_runtime_pollServerInit() {
 	netpollGenericInit()
 }
@@ -134,7 +134,7 @@ func netpollinited() bool {
 	return atomic.Load(&netpollInited) != 0
 }
 
-//go:linkname poll_runtime_isPollServerDescriptor internal..z2fpoll.runtime_isPollServerDescriptor
+//go:linkname poll_runtime_isPollServerDescriptor internal_1poll.runtime__isPollServerDescriptor
 
 // poll_runtime_isPollServerDescriptor reports whether fd is a
 // descriptor being used by netpoll.
@@ -142,7 +142,7 @@ func poll_runtime_isPollServerDescriptor(fd uintptr) bool {
 	return netpollIsPollDescriptor(fd)
 }
 
-//go:linkname poll_runtime_pollOpen internal..z2fpoll.runtime_pollOpen
+//go:linkname poll_runtime_pollOpen internal_1poll.runtime__pollOpen
 func poll_runtime_pollOpen(fd uintptr) (uintptr, int) {
 	pd := pollcache.alloc()
 	lock(&pd.lock)
@@ -169,7 +169,7 @@ func poll_runtime_pollOpen(fd uintptr) (uintptr, int) {
 	return uintptr(unsafe.Pointer(pd)), int(errno)
 }
 
-//go:linkname poll_runtime_pollClose internal..z2fpoll.runtime_pollClose
+//go:linkname poll_runtime_pollClose internal_1poll.runtime__pollClose
 func poll_runtime_pollClose(ctx uintptr) {
 	pd := (*pollDesc)(unsafe.Pointer(ctx))
 	if !pd.closing {
@@ -195,7 +195,7 @@ func (c *pollCache) free(pd *pollDesc) {
 // poll_runtime_pollReset, which is internal/poll.runtime_pollReset,
 // prepares a descriptor for polling in mode, which is 'r' or 'w'.
 // This returns an error code; the codes are defined above.
-//go:linkname poll_runtime_pollReset internal..z2fpoll.runtime_pollReset
+//go:linkname poll_runtime_pollReset internal_1poll.runtime__pollReset
 func poll_runtime_pollReset(ctx uintptr, mode int) int {
 	pd := (*pollDesc)(unsafe.Pointer(ctx))
 	errcode := netpollcheckerr(pd, int32(mode))
@@ -214,7 +214,7 @@ func poll_runtime_pollReset(ctx uintptr, mode int) int {
 // waits for a descriptor to be ready for reading or writing,
 // according to mode, which is 'r' or 'w'.
 // This returns an error code; the codes are defined above.
-//go:linkname poll_runtime_pollWait internal..z2fpoll.runtime_pollWait
+//go:linkname poll_runtime_pollWait internal_1poll.runtime__pollWait
 func poll_runtime_pollWait(ctx uintptr, mode int) int {
 	pd := (*pollDesc)(unsafe.Pointer(ctx))
 	errcode := netpollcheckerr(pd, int32(mode))
@@ -237,7 +237,7 @@ func poll_runtime_pollWait(ctx uintptr, mode int) int {
 	return pollNoError
 }
 
-//go:linkname poll_runtime_pollWaitCanceled internal..z2fpoll.runtime_pollWaitCanceled
+//go:linkname poll_runtime_pollWaitCanceled internal_1poll.runtime__pollWaitCanceled
 func poll_runtime_pollWaitCanceled(ctx uintptr, mode int) {
 	pd := (*pollDesc)(unsafe.Pointer(ctx))
 	// This function is used only on windows after a failed attempt to cancel
@@ -246,7 +246,7 @@ func poll_runtime_pollWaitCanceled(ctx uintptr, mode int) {
 	}
 }
 
-//go:linkname poll_runtime_pollSetDeadline internal..z2fpoll.runtime_pollSetDeadline
+//go:linkname poll_runtime_pollSetDeadline internal_1poll.runtime__pollSetDeadline
 func poll_runtime_pollSetDeadline(ctx uintptr, d int64, mode int) {
 	pd := (*pollDesc)(unsafe.Pointer(ctx))
 	lock(&pd.lock)
@@ -330,7 +330,7 @@ func poll_runtime_pollSetDeadline(ctx uintptr, d int64, mode int) {
 	}
 }
 
-//go:linkname poll_runtime_pollUnblock internal..z2fpoll.runtime_pollUnblock
+//go:linkname poll_runtime_pollUnblock internal_1poll.runtime__pollUnblock
 func poll_runtime_pollUnblock(ctx uintptr) {
 	pd := (*pollDesc)(unsafe.Pointer(ctx))
 	lock(&pd.lock)
diff --git a/libgo/go/runtime/pprof/mprof_test.go b/libgo/go/runtime/pprof/mprof_test.go
index 625ab7de..83bf572 100644
--- a/libgo/go/runtime/pprof/mprof_test.go
+++ b/libgo/go/runtime/pprof/mprof_test.go
@@ -91,35 +91,35 @@ func TestMemoryProfiler(t *testing.T) {
 		stk    []string
 		legacy string
 	}{{
-		stk: []string{"pprof.allocatePersistent1K", "runtime/pprof.TestMemoryProfiler"},
+		stk: []string{"runtime/pprof.allocatePersistent1K", "runtime/pprof.TestMemoryProfiler"},
 		legacy: fmt.Sprintf(`%v: %v \[%v: %v\] @ 0x[0-9,a-f x]+
-#	0x[0-9,a-f]+	pprof\.allocatePersistent1K\+0x[0-9,a-f]+	.*/mprof_test\.go:47
+#	0x[0-9,a-f]+	runtime/pprof\.allocatePersistent1K\+0x[0-9,a-f]+	.*/mprof_test\.go:47
 #	0x[0-9,a-f]+	runtime/pprof\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test\.go:82
 `, 32*memoryProfilerRun, 1024*memoryProfilerRun, 32*memoryProfilerRun, 1024*memoryProfilerRun),
 	}, {
-		stk: []string{"pprof.allocateTransient1M", "runtime/pprof.TestMemoryProfiler"},
+		stk: []string{"runtime/pprof.allocateTransient1M", "runtime/pprof.TestMemoryProfiler"},
 		legacy: fmt.Sprintf(`(0|%v): (0|%v) \[%v: %v\] @ 0x[0-9,a-f x]+
-#	0x[0-9,a-f]+	pprof\.allocateTransient1M\+0x[0-9,a-f]+	.*/mprof_test.go:24
+#	0x[0-9,a-f]+	runtime/pprof\.allocateTransient1M\+0x[0-9,a-f]+	.*/mprof_test.go:24
 #	0x[0-9,a-f]+	runtime/pprof\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:79
 `, (1<<10)*memoryProfilerRun, (1<<20)*memoryProfilerRun, (1<<10)*memoryProfilerRun, (1<<20)*memoryProfilerRun),
 	}, {
-		stk: []string{"pprof.allocateTransient2M", "runtime/pprof.TestMemoryProfiler"},
+		stk: []string{"runtime/pprof.allocateTransient2M", "runtime/pprof.TestMemoryProfiler"},
 		// This should start with "0: 0" but gccgo's imprecise
 		// GC means that sometimes the value is not collected.
 		legacy: fmt.Sprintf(`(0|%v): (0|%v) \[%v: %v\] @ 0x[0-9,a-f x]+
-#	0x[0-9,a-f]+	pprof\.allocateTransient2M\+0x[0-9,a-f]+	.*/mprof_test.go:30
+#	0x[0-9,a-f]+	runtime/pprof\.allocateTransient2M\+0x[0-9,a-f]+	.*/mprof_test.go:30
 #	0x[0-9,a-f]+	runtime/pprof\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:80
 `, memoryProfilerRun, (2<<20)*memoryProfilerRun, memoryProfilerRun, (2<<20)*memoryProfilerRun),
 	}, {
-		stk: []string{"pprof.allocateTransient2MInline", "runtime/pprof.TestMemoryProfiler"},
+		stk: []string{"runtime/pprof.allocateTransient2MInline", "runtime/pprof.TestMemoryProfiler"},
 		legacy: fmt.Sprintf(`(0|%v): (0|%v) \[%v: %v\] @ 0x[0-9,a-f x]+
-#	0x[0-9,a-f]+	pprof\.allocateTransient2MInline\+0x[0-9,a-f]+	.*/mprof_test.go:34
+#	0x[0-9,a-f]+	runtime/pprof\.allocateTransient2MInline\+0x[0-9,a-f]+	.*/mprof_test.go:34
 #	0x[0-9,a-f]+	runtime/pprof\.TestMemoryProfiler\+0x[0-9,a-f]+	.*/mprof_test.go:81
 `, memoryProfilerRun, (4<<20)*memoryProfilerRun, memoryProfilerRun, (4<<20)*memoryProfilerRun),
 	}, {
-		stk: []string{"pprof.allocateReflectTransient"},
+		stk: []string{"runtime/pprof.allocateReflectTransient"},
 		legacy: fmt.Sprintf(`(0|%v): (0|%v) \[%v: %v\] @( 0x[0-9,a-f]+)+
-#	0x[0-9,a-f]+	pprof\.allocateReflectTransient\+0x[0-9,a-f]+	.*/mprof_test.go:55
+#	0x[0-9,a-f]+	runtime/pprof\.allocateReflectTransient\+0x[0-9,a-f]+	.*/mprof_test.go:55
 `, memoryProfilerRun, (3<<20)*memoryProfilerRun, memoryProfilerRun, (3<<20)*memoryProfilerRun),
 	}}
 
diff --git a/libgo/go/runtime/pprof/pprof_test.go b/libgo/go/runtime/pprof/pprof_test.go
index ff86bce..7adf891 100644
--- a/libgo/go/runtime/pprof/pprof_test.go
+++ b/libgo/go/runtime/pprof/pprof_test.go
@@ -958,8 +958,8 @@ func TestMutexProfile(t *testing.T) {
 
 		stks := stacks(p)
 		for _, want := range [][]string{
-			// {"sync.(*Mutex).Unlock", "pprof.blockMutex.func1"},
-			{"sync.Mutex.Unlock", "pprof.blockMutex..func1"},
+			// {"sync.(*Mutex).Unlock", "runtime/pprof.blockMutex.func1"},
+			{"sync.Mutex.Unlock", "runtime/pprof.blockMutex..func1"},
 		} {
 			if !containsStack(stks, want) {
 				t.Errorf("No matching stack entry for %+v", want)
diff --git a/libgo/go/runtime/preempt.go b/libgo/go/runtime/preempt.go
index 9a78bcf..8452076 100644
--- a/libgo/go/runtime/preempt.go
+++ b/libgo/go/runtime/preempt.go
@@ -360,7 +360,7 @@ func isAsyncSafePoint(gp *g, pc uintptr) (bool, uintptr) {
 	}
 	name := f.Name()
 	if hasPrefix(name, "runtime.") ||
-		hasPrefix(name, "runtime..z2finternal..z2f") ||
+		hasPrefix(name, "runtime_1internal_1") ||
 		hasPrefix(name, "reflect.") {
 		// For now we never async preempt the runtime or
 		// anything closely tied to the runtime. Known issues
diff --git a/libgo/go/runtime/proc.go b/libgo/go/runtime/proc.go
index 0ca6c02..6c72050 100644
--- a/libgo/go/runtime/proc.go
+++ b/libgo/go/runtime/proc.go
@@ -263,7 +263,7 @@ func main(unsafe.Pointer) {
 }
 
 // os_beforeExit is called from os.Exit(0).
-//go:linkname os_beforeExit os.runtime_beforeExit
+//go:linkname os_beforeExit os.runtime__beforeExit
 func os_beforeExit() {
 	if raceenabled {
 		racefini()
@@ -3305,7 +3305,7 @@ func beforefork() {
 }
 
 // Called from syscall package before fork.
-//go:linkname syscall_runtime_BeforeFork syscall.runtime_BeforeFork
+//go:linkname syscall_runtime_BeforeFork syscall.runtime__BeforeFork
 //go:nosplit
 func syscall_runtime_BeforeFork() {
 	systemstack(beforefork)
@@ -3320,7 +3320,7 @@ func afterfork() {
 }
 
 // Called from syscall package after fork in parent.
-//go:linkname syscall_runtime_AfterFork syscall.runtime_AfterFork
+//go:linkname syscall_runtime_AfterFork syscall.runtime__AfterFork
 //go:nosplit
 func syscall_runtime_AfterFork() {
 	systemstack(afterfork)
@@ -3338,7 +3338,7 @@ var inForkedChild bool
 // temporarily sharing address space with the parent process, this must
 // not change any global variables or calling into C code that may do so.
 //
-//go:linkname syscall_runtime_AfterForkInChild syscall.runtime_AfterForkInChild
+//go:linkname syscall_runtime_AfterForkInChild syscall.runtime__AfterForkInChild
 //go:nosplit
 //go:nowritebarrierrec
 func syscall_runtime_AfterForkInChild() {
@@ -3363,7 +3363,7 @@ func syscall_runtime_AfterForkInChild() {
 var pendingPreemptSignals uint32
 
 // Called from syscall package before Exec.
-//go:linkname syscall_runtime_BeforeExec syscall.runtime_BeforeExec
+//go:linkname syscall_runtime_BeforeExec syscall.runtime__BeforeExec
 func syscall_runtime_BeforeExec() {
 	// Prevent thread creation during exec.
 	execLock.lock()
@@ -3378,7 +3378,7 @@ func syscall_runtime_BeforeExec() {
 }
 
 // Called from syscall package after Exec.
-//go:linkname syscall_runtime_AfterExec syscall.runtime_AfterExec
+//go:linkname syscall_runtime_AfterExec syscall.runtime__AfterExec
 func syscall_runtime_AfterExec() {
 	execLock.unlock()
 }
@@ -5165,7 +5165,7 @@ func (l *gList) pop() *g {
 	return gp
 }
 
-//go:linkname setMaxThreads runtime..z2fdebug.setMaxThreads
+//go:linkname setMaxThreads runtime_1debug.setMaxThreads
 func setMaxThreads(in int) (out int) {
 	lock(&sched.lock)
 	out = int(sched.maxmcount)
@@ -5199,32 +5199,32 @@ func procUnpin() {
 	_g_.m.locks--
 }
 
-//go:linkname sync_runtime_procPin sync.runtime_procPin
+//go:linkname sync_runtime_procPin sync.runtime__procPin
 //go:nosplit
 func sync_runtime_procPin() int {
 	return procPin()
 }
 
-//go:linkname sync_runtime_procUnpin sync.runtime_procUnpin
+//go:linkname sync_runtime_procUnpin sync.runtime__procUnpin
 //go:nosplit
 func sync_runtime_procUnpin() {
 	procUnpin()
 }
 
-//go:linkname sync_atomic_runtime_procPin sync..z2fatomic.runtime_procPin
+//go:linkname sync_atomic_runtime_procPin sync_1atomic.runtime__procPin
 //go:nosplit
 func sync_atomic_runtime_procPin() int {
 	return procPin()
 }
 
-//go:linkname sync_atomic_runtime_procUnpin sync..z2fatomic.runtime_procUnpin
+//go:linkname sync_atomic_runtime_procUnpin sync_1atomic.runtime__procUnpin
 //go:nosplit
 func sync_atomic_runtime_procUnpin() {
 	procUnpin()
 }
 
 // Active spinning for sync.Mutex.
-//go:linkname sync_runtime_canSpin sync.runtime_canSpin
+//go:linkname sync_runtime_canSpin sync.runtime__canSpin
 //go:nosplit
 func sync_runtime_canSpin(i int) bool {
 	// sync.Mutex is cooperative, so we are conservative with spinning.
@@ -5241,7 +5241,7 @@ func sync_runtime_canSpin(i int) bool {
 	return true
 }
 
-//go:linkname sync_runtime_doSpin sync.runtime_doSpin
+//go:linkname sync_runtime_doSpin sync.runtime__doSpin
 //go:nosplit
 func sync_runtime_doSpin() {
 	procyield(active_spin_cnt)
diff --git a/libgo/go/runtime/proflabel.go b/libgo/go/runtime/proflabel.go
index fc655cc..1e1f3bf 100644
--- a/libgo/go/runtime/proflabel.go
+++ b/libgo/go/runtime/proflabel.go
@@ -8,7 +8,7 @@ import "unsafe"
 
 var labelSync uintptr
 
-//go:linkname runtime_setProfLabel runtime..z2fpprof.runtime_setProfLabel
+//go:linkname runtime_setProfLabel runtime_1pprof.runtime__setProfLabel
 func runtime_setProfLabel(labels unsafe.Pointer) {
 	// Introduce race edge for read-back via profile.
 	// This would more properly use &getg().labels as the sync address,
@@ -34,7 +34,7 @@ func runtime_setProfLabel(labels unsafe.Pointer) {
 	getg().labels = labels
 }
 
-//go:linkname runtime_getProfLabel runtime..z2fpprof.runtime_getProfLabel
+//go:linkname runtime_getProfLabel runtime_1pprof.runtime__getProfLabel
 func runtime_getProfLabel() unsafe.Pointer {
 	return getg().labels
 }
diff --git a/libgo/go/runtime/rdebug.go b/libgo/go/runtime/rdebug.go
index 358df11..9c43ce5 100644
--- a/libgo/go/runtime/rdebug.go
+++ b/libgo/go/runtime/rdebug.go
@@ -11,14 +11,14 @@ import _ "unsafe" // for go:linkname
 // maxstacksize.
 var maxstacksize uintptr = 1 << 20 // enough until runtime.main sets it for real
 
-//go:linkname setMaxStack runtime..z2fdebug.setMaxStack
+//go:linkname setMaxStack runtime_1debug.setMaxStack
 func setMaxStack(in int) (out int) {
 	out = int(maxstacksize)
 	maxstacksize = uintptr(in)
 	return out
 }
 
-//go:linkname setPanicOnFault runtime..z2fdebug.setPanicOnFault
+//go:linkname setPanicOnFault runtime_1debug.setPanicOnFault
 func setPanicOnFault(new bool) (old bool) {
 	_g_ := getg()
 	old = _g_.paniconfault
diff --git a/libgo/go/runtime/runtime.go b/libgo/go/runtime/runtime.go
index abc5eab..5af28ae 100644
--- a/libgo/go/runtime/runtime.go
+++ b/libgo/go/runtime/runtime.go
@@ -51,13 +51,13 @@ func tickspersecond() int64 {
 var envs []string
 var argslice []string
 
-//go:linkname syscall_runtime_envs syscall.runtime_envs
+//go:linkname syscall_runtime_envs syscall.runtime__envs
 func syscall_runtime_envs() []string { return append([]string{}, envs...) }
 
 //go:linkname syscall_Getpagesize syscall.Getpagesize
 func syscall_Getpagesize() int { return int(physPageSize) }
 
-//go:linkname os_runtime_args os.runtime_args
+//go:linkname os_runtime_args os.runtime__args
 func os_runtime_args() []string { return append([]string{}, argslice...) }
 
 //go:linkname syscall_Exit syscall.Exit
diff --git a/libgo/go/runtime/runtime1.go b/libgo/go/runtime/runtime1.go
index a8a53d3..39969d1 100644
--- a/libgo/go/runtime/runtime1.go
+++ b/libgo/go/runtime/runtime1.go
@@ -398,7 +398,7 @@ func parsedebugvars() {
 	traceback_env = traceback_cache
 }
 
-//go:linkname setTraceback runtime..z2fdebug.SetTraceback
+//go:linkname setTraceback runtime_1debug.SetTraceback
 func setTraceback(level string) {
 	var t uint32
 	switch level {
diff --git a/libgo/go/runtime/sema.go b/libgo/go/runtime/sema.go
index c1418b3..9a28880 100644
--- a/libgo/go/runtime/sema.go
+++ b/libgo/go/runtime/sema.go
@@ -51,27 +51,27 @@ var semtable [semTabSize]struct {
 	pad  [cpu.CacheLinePadSize - unsafe.Sizeof(semaRoot{})]byte
 }
 
-//go:linkname sync_runtime_Semacquire sync.runtime_Semacquire
+//go:linkname sync_runtime_Semacquire sync.runtime__Semacquire
 func sync_runtime_Semacquire(addr *uint32) {
 	semacquire1(addr, false, semaBlockProfile, 0)
 }
 
-//go:linkname poll_runtime_Semacquire internal..z2fpoll.runtime_Semacquire
+//go:linkname poll_runtime_Semacquire internal_1poll.runtime__Semacquire
 func poll_runtime_Semacquire(addr *uint32) {
 	semacquire1(addr, false, semaBlockProfile, 0)
 }
 
-//go:linkname sync_runtime_Semrelease sync.runtime_Semrelease
+//go:linkname sync_runtime_Semrelease sync.runtime__Semrelease
 func sync_runtime_Semrelease(addr *uint32, handoff bool, skipframes int) {
 	semrelease1(addr, handoff, skipframes)
 }
 
-//go:linkname sync_runtime_SemacquireMutex sync.runtime_SemacquireMutex
+//go:linkname sync_runtime_SemacquireMutex sync.runtime__SemacquireMutex
 func sync_runtime_SemacquireMutex(addr *uint32, lifo bool, skipframes int) {
 	semacquire1(addr, lifo, semaBlockProfile|semaMutexProfile, skipframes)
 }
 
-//go:linkname poll_runtime_Semrelease internal..z2fpoll.runtime_Semrelease
+//go:linkname poll_runtime_Semrelease internal_1poll.runtime__Semrelease
 func poll_runtime_Semrelease(addr *uint32) {
 	semrelease(addr)
 }
@@ -475,7 +475,7 @@ func less(a, b uint32) bool {
 // notifyListAdd adds the caller to a notify list such that it can receive
 // notifications. The caller must eventually call notifyListWait to wait for
 // such a notification, passing the returned ticket number.
-//go:linkname notifyListAdd sync.runtime_notifyListAdd
+//go:linkname notifyListAdd sync.runtime__notifyListAdd
 func notifyListAdd(l *notifyList) uint32 {
 	// This may be called concurrently, for example, when called from
 	// sync.Cond.Wait while holding a RWMutex in read mode.
@@ -484,7 +484,7 @@ func notifyListAdd(l *notifyList) uint32 {
 
 // notifyListWait waits for a notification. If one has been sent since
 // notifyListAdd was called, it returns immediately. Otherwise, it blocks.
-//go:linkname notifyListWait sync.runtime_notifyListWait
+//go:linkname notifyListWait sync.runtime__notifyListWait
 func notifyListWait(l *notifyList, t uint32) {
 	lockWithRank(&l.lock, lockRankNotifyList)
 
@@ -518,7 +518,7 @@ func notifyListWait(l *notifyList, t uint32) {
 }
 
 // notifyListNotifyAll notifies all entries in the list.
-//go:linkname notifyListNotifyAll sync.runtime_notifyListNotifyAll
+//go:linkname notifyListNotifyAll sync.runtime__notifyListNotifyAll
 func notifyListNotifyAll(l *notifyList) {
 	// Fast-path: if there are no new waiters since the last notification
 	// we don't need to acquire the lock.
@@ -550,7 +550,7 @@ func notifyListNotifyAll(l *notifyList) {
 }
 
 // notifyListNotifyOne notifies one entry in the list.
-//go:linkname notifyListNotifyOne sync.runtime_notifyListNotifyOne
+//go:linkname notifyListNotifyOne sync.runtime__notifyListNotifyOne
 func notifyListNotifyOne(l *notifyList) {
 	// Fast-path: if there are no new waiters since the last notification
 	// we don't need to acquire the lock at all.
@@ -603,7 +603,7 @@ func notifyListNotifyOne(l *notifyList) {
 	unlock(&l.lock)
 }
 
-//go:linkname notifyListCheck sync.runtime_notifyListCheck
+//go:linkname notifyListCheck sync.runtime__notifyListCheck
 func notifyListCheck(sz uintptr) {
 	if sz != unsafe.Sizeof(notifyList{}) {
 		print("runtime: bad notifyList size - sync=", sz, " runtime=", unsafe.Sizeof(notifyList{}), "\n")
@@ -611,7 +611,7 @@ func notifyListCheck(sz uintptr) {
 	}
 }
 
-//go:linkname sync_nanotime sync.runtime_nanotime
+//go:linkname sync_nanotime sync.runtime__nanotime
 func sync_nanotime() int64 {
 	return nanotime()
 }
diff --git a/libgo/go/runtime/sigqueue.go b/libgo/go/runtime/sigqueue.go
index 7d1028e..ed024e1 100644
--- a/libgo/go/runtime/sigqueue.go
+++ b/libgo/go/runtime/sigqueue.go
@@ -121,7 +121,7 @@ Send:
 
 // Called to receive the next queued signal.
 // Must only be called from a single goroutine at a time.
-//go:linkname signal_recv os..z2fsignal.signal_recv
+//go:linkname signal_recv os_1signal.signal__recv
 func signal_recv() uint32 {
 	for {
 		// Serve any signals from local copy.
@@ -169,7 +169,7 @@ func signal_recv() uint32 {
 // the signal(s) in question, and here we are just waiting to make sure
 // that all the signals have been delivered to the user channels
 // by the os/signal package.
-//go:linkname signalWaitUntilIdle os..z2fsignal.signalWaitUntilIdle
+//go:linkname signalWaitUntilIdle os_1signal.signalWaitUntilIdle
 func signalWaitUntilIdle() {
 	// Although the signals we care about have been removed from
 	// sig.wanted, it is possible that another thread has received
@@ -189,7 +189,7 @@ func signalWaitUntilIdle() {
 }
 
 // Must only be called from a single goroutine at a time.
-//go:linkname signal_enable os..z2fsignal.signal_enable
+//go:linkname signal_enable os_1signal.signal__enable
 func signal_enable(s uint32) {
 	if !sig.inuse {
 		// This is the first call to signal_enable. Initialize.
@@ -217,7 +217,7 @@ func signal_enable(s uint32) {
 }
 
 // Must only be called from a single goroutine at a time.
-//go:linkname signal_disable os..z2fsignal.signal_disable
+//go:linkname signal_disable os_1signal.signal__disable
 func signal_disable(s uint32) {
 	if s >= uint32(len(sig.wanted)*32) {
 		return
@@ -230,7 +230,7 @@ func signal_disable(s uint32) {
 }
 
 // Must only be called from a single goroutine at a time.
-//go:linkname signal_ignore os..z2fsignal.signal_ignore
+//go:linkname signal_ignore os_1signal.signal__ignore
 func signal_ignore(s uint32) {
 	if s >= uint32(len(sig.wanted)*32) {
 		return
@@ -257,7 +257,7 @@ func sigInitIgnored(s uint32) {
 }
 
 // Checked by signal handlers.
-//go:linkname signal_ignored os..z2fsignal.signal_ignored
+//go:linkname signal_ignored os_1signal.signal__ignored
 func signal_ignored(s uint32) bool {
 	i := atomic.Load(&sig.ignored[s/32])
 	return i&(1<<(s&31)) != 0
diff --git a/libgo/go/runtime/slice.go b/libgo/go/runtime/slice.go
index 97b2659..ddd588e 100644
--- a/libgo/go/runtime/slice.go
+++ b/libgo/go/runtime/slice.go
@@ -15,6 +15,7 @@ import (
 //go:linkname panicmakeslicelen
 //go:linkname panicmakeslicecap
 //go:linkname makeslice
+//go:linkname checkMakeSlice
 //go:linkname makeslice64
 //go:linkname growslice
 //go:linkname slicecopy
@@ -91,6 +92,13 @@ func makeslicecopy(et *_type, tolen int, fromlen int, from unsafe.Pointer) unsaf
 }
 
 func makeslice(et *_type, len, cap int) unsafe.Pointer {
+	mem := checkMakeSlice(et, len, cap)
+	return mallocgc(mem, et, true)
+}
+
+// checkMakeSlice is called for append(s, make([]T, len, cap)...) to check
+// the values of len and cap.
+func checkMakeSlice(et *_type, len, cap int) uintptr {
 	mem, overflow := math.MulUintptr(et.size, uintptr(cap))
 	if overflow || mem > maxAlloc || len < 0 || len > cap {
 		// NOTE: Produce a 'len out of range' error instead of a
@@ -104,8 +112,7 @@ func makeslice(et *_type, len, cap int) unsafe.Pointer {
 		}
 		panicmakeslicecap()
 	}
-
-	return mallocgc(mem, et, true)
+	return mem
 }
 
 func makeslice64(et *_type, len64, cap64 int64) unsafe.Pointer {
diff --git a/libgo/go/runtime/symtab.go b/libgo/go/runtime/symtab.go
index bb0b61d..22a2b13 100644
--- a/libgo/go/runtime/symtab.go
+++ b/libgo/go/runtime/symtab.go
@@ -5,6 +5,7 @@
 package runtime
 
 import (
+	"internal/bytealg"
 	_ "unsafe" // for go:linkname
 )
 
@@ -119,7 +120,7 @@ func pcInlineCallers(pc uintptr, locbuf *location, max int32) int32
 // runtime_expandFinalInlineFrame expands the final pc in stk to include all
 // "callers" if pc is inline.
 //
-//go:linkname runtime_expandFinalInlineFrame runtime..z2fpprof.runtime_expandFinalInlineFrame
+//go:linkname runtime_expandFinalInlineFrame runtime_1pprof.runtime__expandFinalInlineFrame
 func runtime_expandFinalInlineFrame(stk []uintptr) []uintptr {
 	if len(stk) == 0 {
 		return stk
@@ -210,42 +211,62 @@ func hexDigitsToRune(digits []byte, ndig int) rune {
 	return rune(result)
 }
 
-// Perform an in-place decoding on the input byte slice. This looks
-// for "..z<hex 2 >", "..u<hex x 4>" and "..U<hex x 8>" and overwrites
-// with the encoded bytes corresponding to the unicode in question.
-// Return value is the number of bytes taken by the result.
-
+// decodeIdentifier performs an in-place decoding on the input byte slice.
+// This undoes the compiler underscore mangling.
+// Returns the number of bytes used by the result.
 func decodeIdentifier(bsl []byte) int {
+	underscoreCodes := map[byte]byte{
+		'_': '_',
+		'0': '.',
+		'1': '/',
+		'2': '*',
+		'3': ',',
+		'4': '{',
+		'5': '}',
+		'6': '[',
+		'7': ']',
+		'8': '(',
+		'9': ')',
+		'a': '"',
+		'b': ' ',
+		'c': ';',
+	}
+
 	j := 0
 	for i := 0; i < len(bsl); i++ {
 		b := bsl[i]
+		if b != '_' || i+1 >= len(bsl) {
+			bsl[j] = b
+			j++
+			continue
+		}
+
+		if d, ok := underscoreCodes[bsl[i+1]]; ok {
+			i++
+			bsl[j] = d
+			j++
+			continue
+		}
+
+		rlen := 0
+		switch bsl[i+1] {
+		case 'x':
+			rlen = 2
+		case 'u':
+			rlen = 4
+		case 'U':
+			rlen = 8
+		}
 
-		if i+1 < len(bsl) && bsl[i] == '.' && bsl[i+1] == '.' {
-			if i+4 < len(bsl) && bsl[i+2] == 'z' {
-				digits := bsl[i+3:]
-				r := hexDigitsToRune(digits, 2)
-				nc := encoderune(bsl[j:], r)
-				j += nc
-				i += 4
-				continue
-			} else if i+6 < len(bsl) && bsl[i+2] == 'u' {
-				digits := bsl[i+3:]
-				r := hexDigitsToRune(digits, 4)
-				nc := encoderune(bsl[j:], r)
-				j += nc
-				i += 6
-				continue
-			} else if i+10 < len(bsl) && bsl[i+2] == 'U' {
-				digits := bsl[i+3:]
-				r := hexDigitsToRune(digits, 8)
-				nc := encoderune(bsl[j:], r)
-				j += nc
-				i += 10
-				continue
-			}
+		if rlen > 0 && i+1+rlen < len(bsl) {
+			r := hexDigitsToRune(bsl[i+2:], rlen)
+			nc := encoderune(bsl[j:], r)
+			j += nc
+			i += rlen + 1
+		} else {
+			bsl[j] = b
+			j++
 		}
-		bsl[j] = b
-		j += 1
 	}
 	return j
 }
@@ -254,6 +275,11 @@ func decodeIdentifier(bsl []byte) int {
 // as used in the compiler.
 
 func demangleSymbol(s string) string {
+	if bytealg.IndexByteString(s, '.') < 0 {
+		// A symbol with no '.' is not a Go symbol.
+		return s
+	}
+
 	bsl := []byte(s)
 	nchars := decodeIdentifier(bsl)
 	bsl = bsl[:nchars]
diff --git a/libgo/go/runtime/trace.go b/libgo/go/runtime/trace.go
index ce185fc..b05f30a 100644
--- a/libgo/go/runtime/trace.go
+++ b/libgo/go/runtime/trace.go
@@ -1152,7 +1152,7 @@ func traceNextGC() {
 // To access runtime functions from runtime/trace.
 // See runtime/trace/annotation.go
 
-//go:linkname trace_userTaskCreate runtime..z2ftrace.userTaskCreate
+//go:linkname trace_userTaskCreate runtime_1trace.userTaskCreate
 func trace_userTaskCreate(id, parentID uint64, taskType string) {
 	if !trace.enabled {
 		return
@@ -1170,12 +1170,12 @@ func trace_userTaskCreate(id, parentID uint64, taskType string) {
 	traceReleaseBuffer(pid)
 }
 
-//go:linkname trace_userTaskEnd runtime..z2ftrace.userTaskEnd
+//go:linkname trace_userTaskEnd runtime_1trace.userTaskEnd
 func trace_userTaskEnd(id uint64) {
 	traceEvent(traceEvUserTaskEnd, 2, id)
 }
 
-//go:linkname trace_userRegion runtime..z2ftrace.userRegion
+//go:linkname trace_userRegion runtime_1trace.userRegion
 func trace_userRegion(id, mode uint64, name string) {
 	if !trace.enabled {
 		return
@@ -1192,7 +1192,7 @@ func trace_userRegion(id, mode uint64, name string) {
 	traceReleaseBuffer(pid)
 }
 
-//go:linkname trace_userLog runtime..z2ftrace.userLog
+//go:linkname trace_userLog runtime_1trace.userLog
 func trace_userLog(id uint64, category, message string) {
 	if !trace.enabled {
 		return
diff --git a/libgo/go/runtime/traceback_gccgo.go b/libgo/go/runtime/traceback_gccgo.go
index 1ba91af..ebdbefc 100644
--- a/libgo/go/runtime/traceback_gccgo.go
+++ b/libgo/go/runtime/traceback_gccgo.go
@@ -184,10 +184,10 @@ func showfuncinfo(name string, firstFrame bool) bool {
 // isExportedRuntime reports whether name is an exported runtime function.
 // It is only for runtime functions, so ASCII A-Z is fine. Here also check
 // for mangled functions from runtime/<...>, which will be prefixed with
-// "runtime..z2f".
+// "runtime_1".
 func isExportedRuntime(name string) bool {
 	const n = len("runtime.")
-	if hasPrefix(name, "runtime..z2f") {
+	if hasPrefix(name, "runtime_1") {
 		return true
 	}
 	return len(name) > n && name[:n] == "runtime." && 'A' <= name[n] && name[n] <= 'Z'
diff --git a/libgo/go/sync/atomic/atomic.c b/libgo/go/sync/atomic/atomic.c
index 90a4ff3..71d51aa 100644
--- a/libgo/go/sync/atomic/atomic.c
+++ b/libgo/go/sync/atomic/atomic.c
@@ -9,7 +9,7 @@
 #include "runtime.h"
 
 int32_t SwapInt32 (int32_t *, int32_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.SwapInt32")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.SwapInt32")
   __attribute__ ((no_split_stack));
 
 int32_t
@@ -19,7 +19,7 @@ SwapInt32 (int32_t *addr, int32_t new)
 }
 
 int64_t SwapInt64 (int64_t *, int64_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.SwapInt64")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.SwapInt64")
   __attribute__ ((no_split_stack));
 
 int64_t
@@ -31,7 +31,7 @@ SwapInt64 (int64_t *addr, int64_t new)
 }
 
 uint32_t SwapUint32 (uint32_t *, uint32_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.SwapUint32")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.SwapUint32")
   __attribute__ ((no_split_stack));
 
 uint32_t
@@ -41,7 +41,7 @@ SwapUint32 (uint32_t *addr, uint32_t new)
 }
 
 uint64_t SwapUint64 (uint64_t *, uint64_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.SwapUint64")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.SwapUint64")
   __attribute__ ((no_split_stack));
 
 uint64_t
@@ -53,7 +53,7 @@ SwapUint64 (uint64_t *addr, uint64_t new)
 }
 
 uintptr_t SwapUintptr (uintptr_t *, uintptr_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.SwapUintptr")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.SwapUintptr")
   __attribute__ ((no_split_stack));
 
 uintptr_t
@@ -63,7 +63,7 @@ SwapUintptr (uintptr_t *addr, uintptr_t new)
 }
 
 _Bool CompareAndSwapInt32 (int32_t *, int32_t, int32_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.CompareAndSwapInt32")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.CompareAndSwapInt32")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -74,7 +74,7 @@ CompareAndSwapInt32 (int32_t *val, int32_t old, int32_t new)
 }
 
 _Bool CompareAndSwapInt64 (int64_t *, int64_t, int64_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.CompareAndSwapInt64")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.CompareAndSwapInt64")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -87,7 +87,7 @@ CompareAndSwapInt64 (int64_t *val, int64_t old, int64_t new)
 }
 
 _Bool CompareAndSwapUint32 (uint32_t *, uint32_t, uint32_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.CompareAndSwapUint32")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.CompareAndSwapUint32")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -98,7 +98,7 @@ CompareAndSwapUint32 (uint32_t *val, uint32_t old, uint32_t new)
 }
 
 _Bool CompareAndSwapUint64 (uint64_t *, uint64_t, uint64_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.CompareAndSwapUint64")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.CompareAndSwapUint64")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -111,7 +111,7 @@ CompareAndSwapUint64 (uint64_t *val, uint64_t old, uint64_t new)
 }
 
 _Bool CompareAndSwapUintptr (uintptr_t *, uintptr_t, uintptr_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.CompareAndSwapUintptr")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.CompareAndSwapUintptr")
   __attribute__ ((no_split_stack));
 
 _Bool
@@ -122,7 +122,7 @@ CompareAndSwapUintptr (uintptr_t *val, uintptr_t old, uintptr_t new)
 }
 
 int32_t AddInt32 (int32_t *, int32_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.AddInt32")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.AddInt32")
   __attribute__ ((no_split_stack));
 
 int32_t
@@ -132,7 +132,7 @@ AddInt32 (int32_t *val, int32_t delta)
 }
 
 uint32_t AddUint32 (uint32_t *, uint32_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.AddUint32")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.AddUint32")
   __attribute__ ((no_split_stack));
 
 uint32_t
@@ -142,7 +142,7 @@ AddUint32 (uint32_t *val, uint32_t delta)
 }
 
 int64_t AddInt64 (int64_t *, int64_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.AddInt64")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.AddInt64")
   __attribute__ ((no_split_stack));
 
 int64_t
@@ -154,7 +154,7 @@ AddInt64 (int64_t *val, int64_t delta)
 }
 
 uint64_t AddUint64 (uint64_t *, uint64_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.AddUint64")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.AddUint64")
   __attribute__ ((no_split_stack));
 
 uint64_t
@@ -166,7 +166,7 @@ AddUint64 (uint64_t *val, uint64_t delta)
 }
 
 uintptr_t AddUintptr (uintptr_t *, uintptr_t)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.AddUintptr")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.AddUintptr")
   __attribute__ ((no_split_stack));
 
 uintptr_t
@@ -176,7 +176,7 @@ AddUintptr (uintptr_t *val, uintptr_t delta)
 }
 
 int32_t LoadInt32 (int32_t *addr)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.LoadInt32")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.LoadInt32")
   __attribute__ ((no_split_stack));
 
 int32_t
@@ -186,7 +186,7 @@ LoadInt32 (int32_t *addr)
 }
 
 int64_t LoadInt64 (int64_t *addr)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.LoadInt64")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.LoadInt64")
   __attribute__ ((no_split_stack));
 
 int64_t
@@ -198,7 +198,7 @@ LoadInt64 (int64_t *addr)
 }
 
 uint32_t LoadUint32 (uint32_t *addr)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.LoadUint32")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.LoadUint32")
   __attribute__ ((no_split_stack));
 
 uint32_t
@@ -208,7 +208,7 @@ LoadUint32 (uint32_t *addr)
 }
 
 uint64_t LoadUint64 (uint64_t *addr)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.LoadUint64")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.LoadUint64")
   __attribute__ ((no_split_stack));
 
 uint64_t
@@ -220,7 +220,7 @@ LoadUint64 (uint64_t *addr)
 }
 
 uintptr_t LoadUintptr (uintptr_t *addr)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.LoadUintptr")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.LoadUintptr")
   __attribute__ ((no_split_stack));
 
 uintptr_t
@@ -230,7 +230,7 @@ LoadUintptr (uintptr_t *addr)
 }
 
 void *LoadPointer (void **addr)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.LoadPointer")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.LoadPointer")
   __attribute__ ((no_split_stack));
 
 void *
@@ -240,7 +240,7 @@ LoadPointer (void **addr)
 }
 
 void StoreInt32 (int32_t *addr, int32_t val)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.StoreInt32")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.StoreInt32")
   __attribute__ ((no_split_stack));
 
 void
@@ -250,7 +250,7 @@ StoreInt32 (int32_t *addr, int32_t val)
 }
 
 void StoreInt64 (int64_t *addr, int64_t val)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.StoreInt64")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.StoreInt64")
   __attribute__ ((no_split_stack));
 
 void
@@ -262,7 +262,7 @@ StoreInt64 (int64_t *addr, int64_t val)
 }
 
 void StoreUint32 (uint32_t *addr, uint32_t val)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.StoreUint32")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.StoreUint32")
   __attribute__ ((no_split_stack));
 
 void
@@ -272,7 +272,7 @@ StoreUint32 (uint32_t *addr, uint32_t val)
 }
 
 void StoreUint64 (uint64_t *addr, uint64_t val)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.StoreUint64")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.StoreUint64")
   __attribute__ ((no_split_stack));
 
 void
@@ -284,7 +284,7 @@ StoreUint64 (uint64_t *addr, uint64_t val)
 }
 
 void StoreUintptr (uintptr_t *addr, uintptr_t val)
-  __asm__ (GOSYM_PREFIX "sync..z2fatomic.StoreUintptr")
+  __asm__ (GOSYM_PREFIX "sync_1atomic.StoreUintptr")
   __attribute__ ((no_split_stack));
 
 void
diff --git a/libgo/gotool-packages.txt b/libgo/gotool-packages.txt
index 745c34c..c11df02 100644
--- a/libgo/gotool-packages.txt
+++ b/libgo/gotool-packages.txt
@@ -43,6 +43,7 @@ cmd/internal/buildid
 cmd/internal/diff
 cmd/internal/edit
 cmd/internal/objabi
+cmd/internal/pkgpath
 cmd/internal/sys
 cmd/internal/test2json
 golang.org/x/crypto/ed25519
diff --git a/libgo/misc/cgo/errors/badsym_test.go b/libgo/misc/cgo/errors/badsym_test.go
new file mode 100644
index 0000000..b2701bf9
--- /dev/null
+++ b/libgo/misc/cgo/errors/badsym_test.go
@@ -0,0 +1,216 @@
+// Copyright 2020 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 errorstest
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+	"unicode"
+)
+
+// A manually modified object file could pass unexpected characters
+// into the files generated by cgo.
+
+const magicInput = "abcdefghijklmnopqrstuvwxyz0123"
+const magicReplace = "\n//go:cgo_ldflag \"-badflag\"\n//"
+
+const cSymbol = "BadSymbol" + magicInput + "Name"
+const cDefSource = "int " + cSymbol + " = 1;"
+const cRefSource = "extern int " + cSymbol + "; int F() { return " + cSymbol + "; }"
+
+// goSource is the source code for the trivial Go file we use.
+// We will replace TMPDIR with the temporary directory name.
+const goSource = `
+package main
+
+// #cgo LDFLAGS: TMPDIR/cbad.o TMPDIR/cbad.so
+// extern int F();
+import "C"
+
+func main() {
+	println(C.F())
+}
+`
+
+func TestBadSymbol(t *testing.T) {
+	dir := t.TempDir()
+
+	mkdir := func(base string) string {
+		ret := filepath.Join(dir, base)
+		if err := os.Mkdir(ret, 0755); err != nil {
+			t.Fatal(err)
+		}
+		return ret
+	}
+
+	cdir := mkdir("c")
+	godir := mkdir("go")
+
+	makeFile := func(mdir, base, source string) string {
+		ret := filepath.Join(mdir, base)
+		if err := ioutil.WriteFile(ret, []byte(source), 0644); err != nil {
+			t.Fatal(err)
+		}
+		return ret
+	}
+
+	cDefFile := makeFile(cdir, "cdef.c", cDefSource)
+	cRefFile := makeFile(cdir, "cref.c", cRefSource)
+
+	ccCmd := cCompilerCmd(t)
+
+	cCompile := func(arg, base, src string) string {
+		out := filepath.Join(cdir, base)
+		run := append(ccCmd, arg, "-o", out, src)
+		output, err := exec.Command(run[0], run[1:]...).CombinedOutput()
+		if err != nil {
+			t.Log(run)
+			t.Logf("%s", output)
+			t.Fatal(err)
+		}
+		if err := os.Remove(src); err != nil {
+			t.Fatal(err)
+		}
+		return out
+	}
+
+	// Build a shared library that defines a symbol whose name
+	// contains magicInput.
+
+	cShared := cCompile("-shared", "c.so", cDefFile)
+
+	// Build an object file that refers to the symbol whose name
+	// contains magicInput.
+
+	cObj := cCompile("-c", "c.o", cRefFile)
+
+	// Rewrite the shared library and the object file, replacing
+	// magicInput with magicReplace. This will have the effect of
+	// introducing a symbol whose name looks like a cgo command.
+	// The cgo tool will use that name when it generates the
+	// _cgo_import.go file, thus smuggling a magic //go:cgo_ldflag
+	// pragma into a Go file. We used to not check the pragmas in
+	// _cgo_import.go.
+
+	rewrite := func(from, to string) {
+		obj, err := ioutil.ReadFile(from)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if bytes.Count(obj, []byte(magicInput)) == 0 {
+			t.Fatalf("%s: did not find magic string", from)
+		}
+
+		if len(magicInput) != len(magicReplace) {
+			t.Fatalf("internal test error: different magic lengths: %d != %d", len(magicInput), len(magicReplace))
+		}
+
+		obj = bytes.ReplaceAll(obj, []byte(magicInput), []byte(magicReplace))
+
+		if err := ioutil.WriteFile(to, obj, 0644); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	cBadShared := filepath.Join(godir, "cbad.so")
+	rewrite(cShared, cBadShared)
+
+	cBadObj := filepath.Join(godir, "cbad.o")
+	rewrite(cObj, cBadObj)
+
+	goSourceBadObject := strings.ReplaceAll(goSource, "TMPDIR", godir)
+	makeFile(godir, "go.go", goSourceBadObject)
+
+	makeFile(godir, "go.mod", "module badsym")
+
+	// Try to build our little package.
+	cmd := exec.Command("go", "build", "-ldflags=-v")
+	cmd.Dir = godir
+	output, err := cmd.CombinedOutput()
+
+	// The build should fail, but we want it to fail because we
+	// detected the error, not because we passed a bad flag to the
+	// C linker.
+
+	if err == nil {
+		t.Errorf("go build succeeded unexpectedly")
+	}
+
+	t.Logf("%s", output)
+
+	for _, line := range bytes.Split(output, []byte("\n")) {
+		if bytes.Contains(line, []byte("dynamic symbol")) && bytes.Contains(line, []byte("contains unsupported character")) {
+			// This is the error from cgo.
+			continue
+		}
+
+		// We passed -ldflags=-v to see the external linker invocation,
+		// which should not include -badflag.
+		if bytes.Contains(line, []byte("-badflag")) {
+			t.Error("output should not mention -badflag")
+		}
+
+		// Also check for compiler errors, just in case.
+		// GCC says "unrecognized command line option".
+		// clang says "unknown argument".
+		if bytes.Contains(line, []byte("unrecognized")) || bytes.Contains(output, []byte("unknown")) {
+			t.Error("problem should have been caught before invoking C linker")
+		}
+	}
+}
+
+func cCompilerCmd(t *testing.T) []string {
+	cc := []string{goEnv(t, "CC")}
+
+	out := goEnv(t, "GOGCCFLAGS")
+	quote := '\000'
+	start := 0
+	lastSpace := true
+	backslash := false
+	s := string(out)
+	for i, c := range s {
+		if quote == '\000' && unicode.IsSpace(c) {
+			if !lastSpace {
+				cc = append(cc, s[start:i])
+				lastSpace = true
+			}
+		} else {
+			if lastSpace {
+				start = i
+				lastSpace = false
+			}
+			if quote == '\000' && !backslash && (c == '"' || c == '\'') {
+				quote = c
+				backslash = false
+			} else if !backslash && quote == c {
+				quote = '\000'
+			} else if (quote == '\000' || quote == '"') && !backslash && c == '\\' {
+				backslash = true
+			} else {
+				backslash = false
+			}
+		}
+	}
+	if !lastSpace {
+		cc = append(cc, s[start:])
+	}
+	return cc
+}
+
+func goEnv(t *testing.T, key string) string {
+	out, err := exec.Command("go", "env", key).CombinedOutput()
+	if err != nil {
+		t.Logf("go env %s\n", key)
+		t.Logf("%s", out)
+		t.Fatal(err)
+	}
+	return strings.TrimSpace(string(out))
+}
diff --git a/libgo/mksysinfo.sh b/libgo/mksysinfo.sh
index deac5ce..b32a026 100755
--- a/libgo/mksysinfo.sh
+++ b/libgo/mksysinfo.sh
@@ -194,6 +194,7 @@ fi
 
 # Networking constants.
 egrep '^const _(AF|ARPHRD|ETH|IN|SOCK|SOL|SO|IPPROTO|TCP|IP|IPV6)_' gen-sysinfo.go |
+  grep -v '_val =' |
   sed -e 's/^\(const \)_\([^= ]*\)\(.*\)$/\1\2 = _\2/' >> ${OUT}
 grep '^const _SOMAXCONN' gen-sysinfo.go |
   sed -e 's/^\(const \)_\(SOMAXCONN[^= ]*\)\(.*\)$/\1\2 = _\2/' \
@@ -213,6 +214,14 @@ for m in SOCK_CLOEXEC SOCK_NONBLOCK; do
   fi
 done
 
+# On 32-bit GNU/Linux the expression for SO_RCVTIMEO is too complicated
+# for -fdump-go-spec.
+if ! grep '^const SO_RCVTIMEO ' ${OUT} >/dev/null 2>&1; then
+  if grep '^const _SO_RCVTIMEO_val' ${OUT} >/dev/null 2>&1; then
+    echo 'const SO_RCVTIMEO = _SO_RCVTIMEO_val' >> ${OUT}
+  fi
+fi
+
 # The syscall package requires AF_LOCAL.
 if ! grep '^const AF_LOCAL ' ${OUT} >/dev/null 2>&1; then
   if grep '^const AF_UNIX ' ${OUT} >/dev/null 2>&1; then
diff --git a/libgo/runtime/go-cdiv.c b/libgo/runtime/go-cdiv.c
deleted file mode 100644
index 0355e26..0000000
--- a/libgo/runtime/go-cdiv.c
+++ /dev/null
@@ -1,49 +0,0 @@
-/* go-cdiv.c -- complex division routines
-
-   Copyright 2013 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.  */
-
-#include <complex.h>
-#include <math.h>
-
-/* Calls to these functions are generated by the Go frontend for
-   division of complex64 or complex128.  We use these because Go's
-   complex division expects slightly different results from the GCC
-   default.  When dividing NaN+1.0i / 0+0i, Go expects NaN+NaNi but
-   GCC generates NaN+Infi.  NaN+Infi seems wrong seems the rules of
-   C99 Annex G specify that if either side of a complex number is Inf,
-   the the whole number is Inf, but an operation involving NaN ought
-   to result in NaN, not Inf.  */
-
-complex float
-__go_complex64_div (complex float a, complex float b)
-{
-  if (__builtin_expect (b == 0, 0))
-    {
-      if (!isinf (crealf (a))
-	  && !isinf (cimagf (a))
-	  && (isnan (crealf (a)) || isnan (cimagf (a))))
-	{
-	  /* Pass "1" to nanf to match math/bits.go.  */
-	  return nanf("1") + nanf("1")*I;
-	}
-    }
-  return a / b;
-}
-
-complex double
-__go_complex128_div (complex double a, complex double b)
-{
-  if (__builtin_expect (b == 0, 0))
-    {
-      if (!isinf (creal (a))
-	  && !isinf (cimag (a))
-	  && (isnan (creal (a)) || isnan (cimag (a))))
-	{
-	  /* Pass "1" to nan to match math/bits.go.  */
-	  return nan("1") + nan("1")*I;
-	}
-    }
-  return a / b;
-}
diff --git a/libgo/runtime/go-ffi.c b/libgo/runtime/go-ffi.c
index b030f5e..1ec5f87 100644
--- a/libgo/runtime/go-ffi.c
+++ b/libgo/runtime/go-ffi.c
@@ -16,36 +16,36 @@
    the libffi type values.  */
 
 ffi_type *go_ffi_type_pointer(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_pointer(void) __asm__ ("runtime.ffi_type_pointer");
+ffi_type *go_ffi_type_pointer(void) __asm__ ("runtime.ffi__type__pointer");
 ffi_type *go_ffi_type_sint8(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_sint8(void) __asm__ ("runtime.ffi_type_sint8");
+ffi_type *go_ffi_type_sint8(void) __asm__ ("runtime.ffi__type__sint8");
 ffi_type *go_ffi_type_sint16(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_sint16(void) __asm__ ("runtime.ffi_type_sint16");
+ffi_type *go_ffi_type_sint16(void) __asm__ ("runtime.ffi__type__sint16");
 ffi_type *go_ffi_type_sint32(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_sint32(void) __asm__ ("runtime.ffi_type_sint32");
+ffi_type *go_ffi_type_sint32(void) __asm__ ("runtime.ffi__type__sint32");
 ffi_type *go_ffi_type_sint64(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_sint64(void) __asm__ ("runtime.ffi_type_sint64");
+ffi_type *go_ffi_type_sint64(void) __asm__ ("runtime.ffi__type__sint64");
 ffi_type *go_ffi_type_uint8(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_uint8(void) __asm__ ("runtime.ffi_type_uint8");
+ffi_type *go_ffi_type_uint8(void) __asm__ ("runtime.ffi__type__uint8");
 ffi_type *go_ffi_type_uint16(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_uint16(void) __asm__ ("runtime.ffi_type_uint16");
+ffi_type *go_ffi_type_uint16(void) __asm__ ("runtime.ffi__type__uint16");
 ffi_type *go_ffi_type_uint32(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_uint32(void) __asm__ ("runtime.ffi_type_uint32");
+ffi_type *go_ffi_type_uint32(void) __asm__ ("runtime.ffi__type__uint32");
 ffi_type *go_ffi_type_uint64(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_uint64(void) __asm__ ("runtime.ffi_type_uint64");
+ffi_type *go_ffi_type_uint64(void) __asm__ ("runtime.ffi__type__uint64");
 ffi_type *go_ffi_type_float(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_float(void) __asm__ ("runtime.ffi_type_float");
+ffi_type *go_ffi_type_float(void) __asm__ ("runtime.ffi__type__float");
 ffi_type *go_ffi_type_double(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_double(void) __asm__ ("runtime.ffi_type_double");
+ffi_type *go_ffi_type_double(void) __asm__ ("runtime.ffi__type__double");
 ffi_type *go_ffi_type_complex_float(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_complex_float(void) __asm__ ("runtime.ffi_type_complex_float");
+ffi_type *go_ffi_type_complex_float(void) __asm__ ("runtime.ffi__type__complex__float");
 ffi_type *go_ffi_type_complex_double(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_complex_double(void) __asm__ ("runtime.ffi_type_complex_double");
+ffi_type *go_ffi_type_complex_double(void) __asm__ ("runtime.ffi__type__complex__double");
 ffi_type *go_ffi_type_void(void) __attribute__ ((no_split_stack));
-ffi_type *go_ffi_type_void(void) __asm__ ("runtime.ffi_type_void");
+ffi_type *go_ffi_type_void(void) __asm__ ("runtime.ffi__type__void");
 
 _Bool go_ffi_supports_complex(void) __attribute__ ((no_split_stack));
-_Bool go_ffi_supports_complex(void) __asm__ ("runtime.ffi_supports_complex");
+_Bool go_ffi_supports_complex(void) __asm__ ("runtime.ffi__supports__complex");
 
 ffi_type *
 go_ffi_type_pointer(void)
diff --git a/libgo/runtime/go-setenv.c b/libgo/runtime/go-setenv.c
index 81b1775..08987de 100644
--- a/libgo/runtime/go-setenv.c
+++ b/libgo/runtime/go-setenv.c
@@ -13,7 +13,7 @@
 
 /* Set the C environment from Go.  This is called by syscall.Setenv.  */
 
-void setenv_c (String, String) __asm__ (GOSYM_PREFIX "syscall.setenv_c");
+void setenv_c (String, String) __asm__ (GOSYM_PREFIX "syscall.setenv__c");
 
 void
 setenv_c (String k, String v)
diff --git a/libgo/runtime/go-unsafe-pointer.c b/libgo/runtime/go-unsafe-pointer.c
index 364878e..e24bfb2 100644
--- a/libgo/runtime/go-unsafe-pointer.c
+++ b/libgo/runtime/go-unsafe-pointer.c
@@ -72,7 +72,7 @@ const struct _type unsafe_Pointer =
    it to be defined elsewhere.  */
 
 extern const struct ptrtype pointer_unsafe_Pointer
-  __asm__ (GOSYM_PREFIX "type...1unsafe.Pointer");
+  __asm__ (GOSYM_PREFIX "unsafe.Pointer..p");
 
 /* The reflection string.  */
 #define PREFLECTION "*unsafe.Pointer"
@@ -83,7 +83,7 @@ static const String preflection_string =
 };
 
 extern const byte pointer_unsafe_Pointer_gc[]
-  __asm__ (GOSYM_PREFIX "type...1unsafe.Pointer..g");
+  __asm__ (GOSYM_PREFIX "unsafe.Pointer..p..g");
 
 const byte pointer_unsafe_Pointer_gc[] = { 1 };
 
diff --git a/libgo/runtime/go-unsetenv.c b/libgo/runtime/go-unsetenv.c
index 2135997..4b5058a 100644
--- a/libgo/runtime/go-unsetenv.c
+++ b/libgo/runtime/go-unsetenv.c
@@ -14,7 +14,7 @@
 /* Unset an environment variable from Go.  This is called by
    syscall.Unsetenv.  */
 
-void unsetenv_c (String) __asm__ (GOSYM_PREFIX "syscall.unsetenv_c");
+void unsetenv_c (String) __asm__ (GOSYM_PREFIX "syscall.unsetenv__c");
 
 void
 unsetenv_c (String k)
diff --git a/libgo/runtime/runtime.h b/libgo/runtime/runtime.h
index f46eaea..3a65d44 100644
--- a/libgo/runtime/runtime.h
+++ b/libgo/runtime/runtime.h
@@ -440,7 +440,7 @@ void	runtime_freedefer(Defer*);
 
 extern void _cgo_wait_runtime_init_done (void);
 extern void _cgo_notify_runtime_init_done (void)
-  __asm__ (GOSYM_PREFIX "runtime._cgo_notify_runtime_init_done");
+  __asm__ (GOSYM_PREFIX "runtime.__cgo__notify__runtime__init__done");
 extern _Bool runtime_iscgo;
 extern uintptr __go_end __attribute__ ((weak));
 extern void *getitab(const struct _type *, const struct _type *, _Bool)
diff --git a/libgo/sysinfo.c b/libgo/sysinfo.c
index 7086381..a060ea8 100644
--- a/libgo/sysinfo.c
+++ b/libgo/sysinfo.c
@@ -337,6 +337,9 @@ enum {
 #ifdef BIOCVERSION
   BIOCVERSION_val = BIOCVERSION,
 #endif
+#ifdef SO_RCVTIMEO
+  SO_RCVTIMEO_val = SO_RCVTIMEO,
+#endif
 };
 
 // SIOCGIFMTU can't be added in the above enum as it might
diff --git a/libgo/testsuite/gotest b/libgo/testsuite/gotest
index 0fd6419..8c3c5ca 100755
--- a/libgo/testsuite/gotest
+++ b/libgo/testsuite/gotest
@@ -496,7 +496,8 @@ testname() {
 localname() {
 	# The package main has been renamed to __main__ when imported.
 	# Adjust its uses.
-	echo $1 | sed 's/^main\./__main__./'
+	# Also demangle underscores.
+	echo $1 | sed 's/^main\./__main__./' | sed 's/__/_/'
 }
 
 # Takes a list of tests derived from 'nm' output (whose symbols are mangled)
@@ -504,7 +505,7 @@ localname() {
 # Example:
 #
 #    Original symbol:   foo/bar/leaf.Mumble
-#    Mangled symbol:    foo..z2fbar..z2fleaf.Mumble
+#    Mangled symbol:    foo_1fbar_1leaf.Mumble
 #    Returned:          leaf.Mumble
 #
 symtogo() {
@@ -522,7 +523,7 @@ symtogo() {
     if expr "$tp" : '^type\.\.' >/dev/null 2>&1; then
       continue
     fi
-    s=$(echo "$tp" | sed -e 's/\.\.z2f/%/g' | sed -e 's/.*%//')
+    s=$(echo "$tp" | sed -e 's/_1/%/g' | sed -e 's/.*%//')
     # Screen out methods (X.Y.Z).
     if ! expr "$s" : '^[^.]*\.[^.]*$' >/dev/null 2>&1; then
       continue