cmd/dist, misc/cgo/testsanitizers: enable msan tests on freebsd/amd64

Adjust os/arch checks to enable msan tests on freebsd/amd64.

R=go1.20

For #53298

Change-Id: I3d0f5259db73d526d006a12de5ba6284528cf819
Reviewed-on: https://go-review.googlesource.com/c/go/+/411276
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

misc/cgo/testsanitizers/cc_test.go

@@ -540,6 +540,8 @@ func mSanSupported(goos, goarch string) bool {
 	switch goos {
 	case "linux":
 		return goarch == "amd64" || goarch == "arm64"
+	case "freebsd":
+		return goarch == "amd64"
 	default:
 		return false
 	}

misc/cgo/testsanitizers/msan_test.go

@@ -24,7 +24,11 @@ func TestMSAN(t *testing.T) {
 	}
 
 	t.Parallel()
-	requireOvercommit(t)
+	// Overcommit is enabled by default on FreeBSD (vm.overcommit=0, see tuning(7)).
+	// Do not skip tests with stricter overcommit settings unless testing shows that FreeBSD has similar issues.
+	if goos == "linux" {
+		requireOvercommit(t)
+	}
 	config := configure("memory")
 	config.skipIfCSanitizerBroken(t)
 

src/cmd/dist/test.go

@@ -832,8 +832,9 @@ func (t *tester) registerTests() {
 		if gohostos == "linux" && (goarch == "amd64" || goarch == "ppc64le") {
 			t.registerTest("testasan", "../misc/cgo/testasan", "go", "run", ".")
 		}
-		if goos == "linux" {
-			// because syscall.SysProcAttr struct used in misc/cgo/testsanitizers is only built on linux.
+		if goos == "linux" || (goos == "freebsd" && goarch == "amd64") {
+			// because Pdeathsig of syscall.SysProcAttr struct used in misc/cgo/testsanitizers is only
+			// supported on Linux and FreeBSD.
 			t.registerHostTest("testsanitizers", "../misc/cgo/testsanitizers", "misc/cgo/testsanitizers", ".")
 		}
 		if t.hasBash() && goos != "android" && !t.iOS() && gohostos != "windows" {