runtime: crash on SI_USER SigPanic signal

Clean up the code a little bit to make it clearer:

Don't check throwsplit for a SI_USER signal.

If throwsplit is set for a SigPanic signal, always throw;
discard any other flags.

Fixes #36420

Change-Id: Ic9dcd1108603d241f71c040504dfdc6e528f9767
Reviewed-on: https://go-review.googlesource.com/c/go/+/228900
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/runtime/crash_cgo_test.go b/src/runtime/crash_cgo_test.go
index a09ecd8e42..a4d0ebfcd6 100644
--- a/src/runtime/crash_cgo_test.go
+++ b/src/runtime/crash_cgo_test.go
@@ -555,3 +555,21 @@ func findTrace(text, top string) []string {
 	}
 	return nil
 }
+
+func TestSegv(t *testing.T) {
+	switch runtime.GOOS {
+	case "plan9", "windows":
+		t.Skipf("no signals on %s", runtime.GOOS)
+	}
+
+	for _, test := range []string{"Segv", "SegvInCgo"} {
+		t.Run(test, func(t *testing.T) {
+			t.Parallel()
+			got := runTestProg(t, "testprogcgo", test)
+			t.Log(got)
+			if !strings.Contains(got, "SIGSEGV") {
+				t.Errorf("expected crash from signal")
+			}
+		})
+	}
+}