runtime: ignore exceptions from non-Go threads on windows arm/arm64

If there is no current G while handling an exception it means
the exception was originated in a non-Go thread.

The best we can do is ignore the exception and let it flow
through other vectored and structured error handlers.

I've removed badsignal2 from sigtramp because we can't really know
if the signal is bad or not, it might be handled later in the chain.

Fixes #50877
Updates #56082

Change-Id: Ica159eb843629986d1fb5482f0b59a9c1ed91698
Reviewed-on: https://go-review.googlesource.com/c/go/+/442896
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
Reviewed-by: David Chase <drchase@google.com>

src/runtime/signal_windows_test.go

@@ -17,6 +17,61 @@ import (
 	"testing"
 )
 
+func TestVectoredHandlerExceptionInNonGoThread(t *testing.T) {
+	if *flagQuick {
+		t.Skip("-quick")
+	}
+	testenv.MustHaveGoBuild(t)
+	testenv.MustHaveCGO(t)
+	testenv.MustHaveExecPath(t, "g++")
+	testprog.Lock()
+	defer testprog.Unlock()
+	dir := t.TempDir()
+
+	// build c program
+	dll := filepath.Join(dir, "veh.dll")
+	cmd := exec.Command("g++", "-shared", "-o", dll, "testdata/testwinlibthrow/veh.cpp", "-static", "-lstdc++")
+	out, err := testenv.CleanCmdEnv(cmd).CombinedOutput()
+	if err != nil {
+		t.Fatalf("failed to build c exe: %s\n%s", err, out)
+	}
+
+	// build go exe
+	exe := filepath.Join(dir, "test.exe")
+	cmd = exec.Command(testenv.GoToolPath(t), "build", "-o", exe, "testdata/testwinlibthrow/main.go")
+	out, err = testenv.CleanCmdEnv(cmd).CombinedOutput()
+	if err != nil {
+		t.Fatalf("failed to build go library: %s\n%s", err, out)
+	}
+
+	// run test program in same thread
+	cmd = exec.Command(exe)
+	out, err = testenv.CleanCmdEnv(cmd).CombinedOutput()
+	if err == nil {
+		t.Fatal("error expected")
+	}
+	if _, ok := err.(*exec.ExitError); ok && len(out) > 0 {
+		if !bytes.Contains(out, []byte("Exception 0x2a")) {
+			t.Fatalf("unexpected failure while running executable: %s\n%s", err, out)
+		}
+	} else {
+		t.Fatalf("unexpected error while running executable: %s\n%s", err, out)
+	}
+	// run test program in a new thread
+	cmd = exec.Command(exe, "thread")
+	out, err = testenv.CleanCmdEnv(cmd).CombinedOutput()
+	if err == nil {
+		t.Fatal("error expected")
+	}
+	if err, ok := err.(*exec.ExitError); ok {
+		if err.ExitCode() != 42 {
+			t.Fatalf("unexpected failure while running executable: %s\n%s", err, out)
+		}
+	} else {
+		t.Fatalf("unexpected error while running executable: %s\n%s", err, out)
+	}
+}
+
 func TestVectoredHandlerDontCrashOnLibrary(t *testing.T) {
 	if *flagQuick {
 		t.Skip("-quick")

src/runtime/sys_windows_arm.s

@@ -123,8 +123,14 @@ TEXT sigtramp<>(SB),NOSPLIT|NOFRAME,$0
 	MOVW	R1, R7			// Save param1
 
 	BL      runtime·load_g(SB)
-	CMP	$0, g			// is there a current g?
-	BL.EQ	runtime·badsignal2(SB)
+	CMP	$0,	g		// is there a current g?
+	BNE	g_ok
+	ADD	$(8+20), R13	// free locals
+	MOVM.IA.W (R13), [R3, R4-R11, R14]	// pop {r3, r4-r11, lr}
+	MOVW	$0, R0		// continue 
+	BEQ	return
+
+g_ok:
 
 	// save g and SP in case of stack switch
 	MOVW	R13, 24(R13)

src/runtime/sys_windows_arm64.s

@@ -147,10 +147,15 @@ TEXT sigtramp<>(SB),NOSPLIT|NOFRAME,$0
 	MOVD	g, R17 			// saved R28 (callee-save from Windows, not really g)
 
 	BL      runtime·load_g(SB)	// smashes R0, R27, R28 (g)
-	CMP	$0, g			// is there a current g?
-	BNE	2(PC)
-	BL	runtime·badsignal2(SB)
+	CMP	$0,	g		// is there a current g?
+	BNE	g_ok
+	MOVD	R7, LR
+	MOVD	R16, R27	// restore R27
+	MOVD	R17, g		// restore R28
+	MOVD	$0, R0		// continue 
+	RET
 
+g_ok:
 	// Do we need to switch to the g0 stack?
 	MOVD	g, R3			// R3 = oldg (for sigtramp_g0)
 	MOVD	g_m(g), R2		// R2 = m

src/runtime/testdata/testwinlibthrow/main.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"os"
+	"syscall"
+)
+
+func main() {
+	dll := syscall.MustLoadDLL("veh.dll")
+	RaiseExcept := dll.MustFindProc("RaiseExcept")
+	RaiseNoExcept := dll.MustFindProc("RaiseNoExcept")
+	ThreadRaiseExcept := dll.MustFindProc("ThreadRaiseExcept")
+	ThreadRaiseNoExcept := dll.MustFindProc("ThreadRaiseNoExcept")
+
+	thread := len(os.Args) > 1 && os.Args[1] == "thread"
+	if !thread {
+		RaiseExcept.Call()
+		RaiseNoExcept.Call()
+	} else {
+		ThreadRaiseExcept.Call()
+		ThreadRaiseNoExcept.Call()
+	}
+}

src/runtime/testdata/testwinlibthrow/veh.cpp

@@ -0,0 +1,53 @@
+//go:build ignore
+
+#include <windows.h>
+
+extern "C" __declspec(dllexport)
+void RaiseExcept(void)
+{
+    try
+    {
+        RaiseException(42, 0, 0, 0);
+    }
+    catch (...)
+    {
+    }
+}
+
+extern "C" __declspec(dllexport)
+void RaiseNoExcept(void)
+{
+    RaiseException(42, 0, 0, 0);
+}
+
+static DWORD WINAPI ThreadRaiser(void* Context)
+{
+    if (Context)
+        RaiseExcept();
+    else
+        RaiseNoExcept();
+    return 0;
+}
+
+static void ThreadRaiseXxx(int except)
+{
+    static int dummy;
+    HANDLE thread = CreateThread(0, 0, ThreadRaiser, except ? &dummy : 0, 0, 0);
+    if (0 != thread)
+    {
+        WaitForSingleObject(thread, INFINITE);
+        CloseHandle(thread);
+    }
+}
+
+extern "C" __declspec(dllexport)
+void ThreadRaiseExcept(void)
+{
+    ThreadRaiseXxx(1);
+}
+
+extern "C" __declspec(dllexport)
+void ThreadRaiseNoExcept(void)
+{
+    ThreadRaiseXxx(0);
+}