runtime: fix cgo signals detection

CL 64070 removed lockOSThread from the cgocall path, but didn't update
the signal-in-cgo detection in sighandler. As a result, signals that
arrive during a cgo call are treated like they arrived during Go
execution, breaking the traceback.

Update the cgo detection to fix the backtrace.

Fixes #47522

Change-Id: I61d77ba6465f55e3e6187246d79675ba8467ec23
Reviewed-on: https://go-review.googlesource.com/c/go/+/339989
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

2 files changed, 49 insertions, 0 deletions

diff --git a/src/runtime/testdata/testprogcgo/panic.go b/src/runtime/testdata/testprogcgo/panic.go
new file mode 100644
index 0000000000..4ddef3abcd
--- /dev/null
+++ b/src/runtime/testdata/testprogcgo/panic.go
@@ -0,0 +1,29 @@
+package main
+
+import "C"
+
+// This program will crash.
+// We want to test unwinding from a cgo callback.
+
+/*
+void panic_callback();
+
+static void call_callback(void) {
+	panic_callback();
+}
+*/
+import "C"
+
+func init() {
+	register("PanicCallback", PanicCallback)
+}
+
+//export panic_callback
+func panic_callback() {
+	var i *int
+	*i = 42
+}
+
+func PanicCallback() {
+	C.call_callback()
+}
diff --git a/src/runtime/testdata/testprogcgo/sigthrow.go b/src/runtime/testdata/testprogcgo/sigthrow.go
new file mode 100644
index 0000000000..665e3b02df
--- /dev/null
+++ b/src/runtime/testdata/testprogcgo/sigthrow.go
@@ -0,0 +1,20 @@
+// Copyright 2021 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 main
+
+// This program will abort.
+
+/*
+#include <stdlib.h>
+*/
+import "C"
+
+func init() {
+	register("Abort", Abort)
+}
+
+func Abort() {
+	C.abort()
+}