runtime/race: adding support for the race detector on other platforms

[owenwaller]

Hi Everyone,

Following on from this discussion on the golang-nuts list, about supporting the race detector on ARM hardware, I'm opening this issue to track the suggestion.

The ThreadSanitizer that the Go race detector is based on supports x86_64, aarch64 (i.e.Arm8 64-bit), mips64 and powerpc64. Currently Go only supports the race detector on x86_64 hardware.

Would it be possible for a future release of Go to support the race detector on the other platforms - aarch64, mips64 and powerpc64.

Thanks

Owen

[ianlancetaylor]

CC @dvyukov

[bradfitz]

No objections, if somebody does the work.

[krytarowski]

I've added NetBSD/amd64 support in LLVM TSan. This could be integrated with golang CI infrastructure.

https://blog.netbsd.org/tnf/entry/the_llvm_thread_sanitizer_has

[bradfitz]

Note that we check in binary blobs to the Go repo:

bradfitz@gdev:~/go$ find . | grep syso$
./src/runtime/race/race_linux_amd64.syso
./src/runtime/race/race_darwin_amd64.syso
./src/runtime/race/race_windows_amd64.syso
./src/runtime/race/race_freebsd_amd64.syso

They are built using:

https://github.com/golang/build/tree/master/cmd/racebuild

[krytarowski]

I've repeated the steps for building race_netbsd_amd64.syso.

$ file ./src/runtime/race/race_netbsd_amd64.syso
./src/runtime/race/race_netbsd_amd64.syso: ELF 64-bit LSB relocatable, x86-64, version 1 (SYSV), not stripped

My golang patch:

diff --git a/src/cmd/go/internal/work/init.go b/src/cmd/go/internal/work/init.go
index 7f894f5c6d..1df9963521 100644
--- a/src/cmd/go/internal/work/init.go
+++ b/src/cmd/go/internal/work/init.go
@@ -43,8 +43,8 @@ func instrumentInit() {
 		fmt.Fprintf(os.Stderr, "-msan is not supported on %s/%s\n", cfg.Goos, cfg.Goarch)
 		os.Exit(2)
 	}
-	if cfg.Goarch != "amd64" || cfg.Goos != "linux" && cfg.Goos != "freebsd" && cfg.Goos != "darwin" && cfg.Goos != "windows" {
-		fmt.Fprintf(os.Stderr, "go %s: -race and -msan are only supported on linux/amd64, freebsd/amd64, darwin/amd64 and windows/amd64\n", flag.Args()[0])
+	if cfg.Goarch != "amd64" || cfg.Goos != "linux" && cfg.Goos != "freebsd" && cfg.Goos != "netbsd" && cfg.Goos != "darwin" && cfg.Goos != "windows" {
+		fmt.Fprintf(os.Stderr, "go %s: -race and -msan are only supported on linux/amd64, freebsd/amd64, netbsd/amd64, darwin/amd64 and windows/amd64\n", flag.Args()[0])
 		os.Exit(2)
 	}
 
diff --git a/src/race.bash b/src/race.bash
index adf2297c2f..84b8df24c7 100755
--- a/src/race.bash
+++ b/src/race.bash
@@ -9,7 +9,7 @@
 set -e
 
 function usage {
-	echo 'race detector is only supported on linux/amd64, freebsd/amd64 and darwin/amd64' 1>&2
+	echo 'race detector is only supported on linux/amd64, freebsd/amd64, netbsd/amd64 and darwin/amd64' 1>&2
 	exit 1
 }
 
@@ -30,6 +30,11 @@ case $(uname) in
 		usage
 	fi
 	;;
+"NetBSD")
+	if [ $(uname -m) != "amd64" ]; then
+		usage
+	fi
+	;;
 *)
 	usage
 	;;

But I'm getting the following error when attempting to use it:

##### Testing packages.
# compress/bzip2 (testmain)
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target free not defined
runtime/race(.text): relocation target free not defined
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target environ not defined
runtime/race(.text): relocation target malloc not defined
runtime/race(.text): relocation target setrlimit not defined
runtime/race(.text): relocation target syscall not defined
runtime/race(.text): relocation target _lwp_self not defined
runtime/race(.text): relocation target syscall not defined
runtime/race(.text): relocation target __errno not defined
runtime/race(.text): relocation target exit not defined
runtime/race(.text): relocation target __libc_thr_yield not defined
/tmp/test/go/pkg/tool/netbsd_amd64/link: too many errors

Investigating.

[krytarowski]

@bradfitz other .syso files seem to have similar symbols undefined. Are there suggestions how to address it?

[bradfitz]

I have no clue. I've never built these binaries before, nor have I worked on the race detector.

Maybe @ianlancetaylor or @dvyukov know.

[ianlancetaylor]

Most likely you need to edit the build constraints in the flie runtime/race/race.go so that your system is recognized.

[krytarowski]

This has improved the situation. I'm now down to unrecognized __ps_strings.

runtime/race(.text): relocation target __ps_strings not defined
runtime/race(.text): relocation target __ps_strings not defined
runtime/race(.text): relocation target __ps_strings not defined
runtime/race(.text): undefined: "__ps_strings"
runtime/race(.text): undefined: "__ps_strings"
runtime/race(.text): undefined: "__ps_strings"

I'm researching how to fix it.

[krytarowski]

http://www.netbsd.org/~kamil/llvm/go-tsan-2017-12-06.txt

Passed 340 of 347 tests (97.98%, 0+, 7-)
0 expected failures (0 has not fail)

[krytarowski]

http://www.netbsd.org/~kamil/llvm/0001-Add-initial-TSan-NetBSD-support.patch

@bradfitz feel free to merge this with HEAD. (my CLA is signed for Google projects)

My .syso file: http://www.netbsd.org/~kamil/llvm/race_netbsd_amd64.syso

Feel free to regenerate it from scratch or take this one as is and commit to the golang repository.

I cannot focus on the racy tests soon, as I'm burdened with MSan now.

[bradfitz]

@krytarowski, the tree is closed right now for release. Only bug fixes can go in, not features.
See https://golang.org/wiki/Go-Release-Cycle (Unlike NetBSD, we intentionally do not have a development branch open during release freezes to encourage people to do boring stuff instead of just hacking on fun stuff)

We can merge fun things in February.

Also, we'd need to generate the syso ourselves (not shipping a random binary off the network), so you'd first need to send a change to x/build/cmd/racebuild

See https://golang.org/doc/contribute.html for how to submit a git patch to Gerrit. We only do it for people in very rare circumstance.

[krytarowski]

OK, thanks. In February hopefully there will be an option to get MSan aboard.

[ceseo]

FYI, I'm working on adding the necessary changes in LLVM TSan so we can get the race detectors on ppc64le.

(edit: sorry, little endian only)

[krytarowski]

Great to see ppc64le development around. FreeBSD is improving their POWER8 support lately.. I would love to see it with NetBSD as well (but hw price isn't easily reachable for a hobbyist).

[ceseo]

@krytarowski if you need machine access, you may try a POWER8 VM in one of our OpenPOWER Mini Clouds, like this.

[krytarowski]

Personally I prefer to use a real hardware when porting the kernel and userland. But thanks!

[gopherbot]

Change https://golang.org/cl/112881 mentions this issue: cmd/racebuild: add linux/ppc64le

[gopherbot]

Change https://golang.org/cl/112880 mentions this issue: cmd/racebuild: add netbsd/amd64

[gopherbot]

Change https://golang.org/cl/99835 mentions this issue: runtime/cgo: Add initial NetBSD Thread Sanitizer support