cmd,runtime: enable race detector on arm64

Changes include:
1. enable compiler option -race for arm64
2. add runtime/race_arm64.s to manage the calls from Go to the compiler-rt runtime
3. change racewalk.go to call racefuncenterfp instead of racefuncenter on arm64 to
   allow the caller pc to be obtained in the asm code before calling the tsan version
4. race_linux_arm64.syso comes from compiler-rt which just supports 48bit VA, compiler-rt
   is fetched from master branch which latest commit is 3aa2b775d08f903f804246af10b

Fixes #25682

Change-Id: I04364c580b8157fd117deecae74a4656ba16e005
Reviewed-on: https://go-review.googlesource.com/c/138675
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/cmd/compile/internal/gc/racewalk.go

@@ -71,14 +71,14 @@ func instrument(fn *Node) {
 		lno := lineno
 		lineno = src.NoXPos
 
-		if thearch.LinkArch.Arch == sys.ArchPPC64LE {
+		if thearch.LinkArch.Arch.Family != sys.AMD64 {
 			fn.Func.Enter.Prepend(mkcall("racefuncenterfp", nil, nil))
 			fn.Func.Exit.Append(mkcall("racefuncexit", nil, nil))
 		} else {
 
 			// nodpc is the PC of the caller as extracted by
 			// getcallerpc. We use -widthptr(FP) for x86.
-			// BUG: This only works for amd64. This will not
+			// This only works for amd64. This will not
 			// work on arm or others that might support
 			// race in the future.
 			nodpc := nodfp.copy()

src/cmd/go/internal/work/init.go

@@ -49,7 +49,7 @@ func instrumentInit() {
 	}
 	if cfg.BuildRace {
 		if !sys.RaceDetectorSupported(cfg.Goos, cfg.Goarch) {
-			fmt.Fprintf(os.Stderr, "go %s: -race is only supported on linux/amd64, linux/ppc64le, freebsd/amd64, netbsd/amd64, darwin/amd64 and windows/amd64\n", flag.Args()[0])
+			fmt.Fprintf(os.Stderr, "go %s: -race is only supported on linux/amd64, linux/ppc64le, linux/arm64, freebsd/amd64, netbsd/amd64, darwin/amd64 and windows/amd64\n", flag.Args()[0])
 			os.Exit(2)
 		}
 	}

src/cmd/internal/sys/supported.go

@@ -9,7 +9,7 @@ package sys
 func RaceDetectorSupported(goos, goarch string) bool {
 	switch goos {
 	case "linux":
-		return goarch == "amd64" || goarch == "ppc64le"
+		return goarch == "amd64" || goarch == "ppc64le" || goarch == "arm64"
 	case "darwin", "freebsd", "netbsd", "windows":
 		return goarch == "amd64"
 	default:

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

@@ -199,8 +199,8 @@ func mustLinkExternal(ctxt *Link) (res bool, reason string) {
 	// When the race flag is set, the LLVM tsan relocatable file is linked
 	// into the final binary, which means external linking is required because
 	// internal linking does not support it.
-	if *flagRace && ctxt.Arch.InFamily(sys.PPC64) {
-		return true, "race on ppc64le"
+	if *flagRace && ctxt.Arch.InFamily(sys.PPC64, sys.ARM64) {
+		return true, "race on " + objabi.GOARCH
 	}
 
 	// Some build modes require work the internal linker cannot do (yet).

src/race.bash

@@ -9,7 +9,7 @@
 set -e
 
 function usage {
-	echo 'race detector is only supported on linux/amd64, linux/ppc64le, freebsd/amd64, netbsd/amd64 and darwin/amd64' 1>&2
+	echo 'race detector is only supported on linux/amd64, linux/ppc64le, linux/arm64, freebsd/amd64, netbsd/amd64 and darwin/amd64' 1>&2
 	exit 1
 }
 
@@ -21,7 +21,7 @@ case $(uname) in
 	fi
 	;;
 "Linux")
-	if [ $(uname -m) != "x86_64" ] && [ $(uname -m) != "ppc64le" ]; then
+	if [ $(uname -m) != "x86_64" ] && [ $(uname -m) != "ppc64le" ] && [ $(uname -m) != "aarch64" ]; then
 		usage
 	fi
 	;;

src/runtime/asm_arm64.s

@@ -18,6 +18,7 @@ TEXT runtime·rt0_go(SB),NOSPLIT,$0
 	// create istack out of the given (operating system) stack.
 	// _cgo_init may update stackguard.
 	MOVD	$runtime·g0(SB), g
+	BL	runtime·save_g(SB)
 	MOVD	RSP, R7
 	MOVD	$(-64*1024)(R7), R0
 	MOVD	R0, g_stackguard0(g)

src/runtime/race/README

@@ -10,3 +10,4 @@ race_linux_amd64.syso built with LLVM fe2c72c59aa7f4afa45e3f65a5d16a374b6cce26 a
 race_linux_ppc64le.syso built with LLVM fe2c72c59aa7f4afa45e3f65a5d16a374b6cce26 and Go 323c85862a7afbde66a3bba0776bf4ba6cd7c030.
 race_netbsd_amd64.syso built with LLVM fe2c72c59aa7f4afa45e3f65a5d16a374b6cce26 and Go 323c85862a7afbde66a3bba0776bf4ba6cd7c030.
 race_windows_amd64.syso built with LLVM ae08a22cc215448aa3ad5a6fb099f6df77e9fa01 and Go 323c85862a7afbde66a3bba0776bf4ba6cd7c030.
+race_linux_arm64.syso built with LLVM 3aa2b775d08f903f804246af10b80a439c16b436 and Go ef2c48659880c7e8a989e6721a21f018790f7793.

src/runtime/race/race.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build race,linux,amd64 race,freebsd,amd64 race,netbsd,amd64 race,darwin,amd64 race,windows,amd64 race,linux,ppc64le
+// +build race,linux,amd64 race,freebsd,amd64 race,netbsd,amd64 race,darwin,amd64 race,windows,amd64 race,linux,ppc64le race,linux,arm64
 
 package race