runtime: handle windows exceptions, even in cgo programs

Fixes #3543.

R=golang-dev, kardianos, rsc
CC=golang-dev, hectorchu, vcc.163
https://golang.org/cl/6245063

src/cmd/dist/buildruntime.c

@@ -227,6 +227,8 @@ ok:
 				aggr = "gobuf";
 			else if(streq(fields.p[1], "WinCall"))
 				aggr = "wincall";
+			else if(streq(fields.p[1], "SEH"))
+				aggr = "seh";
 		}
 		if(hasprefix(lines.p[i], "}"))
 			aggr = nil;

src/pkg/runtime/crash_cgo_test.go

+// Copyright 2012 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.
+
+// +build cgo
+
+package runtime_test
+
+import (
+	"testing"
+)
+
+func TestCgoCrashHandler(t *testing.T) {
+	testCrashHandler(t, &crashTest{Cgo: true})
+}

src/pkg/runtime/crash_test.go

+// Copyright 2012 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 runtime_test
+
+import (
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+	"text/template"
+)
+
+type crashTest struct {
+	Cgo bool
+}
+
+// This test is a separate program, because it is testing
+// both main (m0) and non-main threads (m).
+
+func testCrashHandler(t *testing.T, ct *crashTest) {
+	st := template.Must(template.New("crashSource").Parse(crashSource))
+
+	dir, err := ioutil.TempDir("", "go-build")
+	if err != nil {
+		t.Fatalf("failed to create temp directory: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	src := filepath.Join(dir, "main.go")
+	f, err := os.Create(src)
+	if err != nil {
+		t.Fatalf("failed to create %v: %v", src, err)
+	}
+	err = st.Execute(f, ct)
+	if err != nil {
+		f.Close()
+		t.Fatalf("failed to execute template: %v", err)
+	}
+	f.Close()
+
+	got, err := exec.Command("go", "run", src).CombinedOutput()
+	if err != nil {
+		t.Fatalf("program exited with error: %v\n%v", err, string(got))
+	}
+	want := "main: recovered done\nnew-thread: recovered done\nsecond-new-thread: recovered done\nmain-again: recovered done\n"
+	if string(got) != string(want) {
+		t.Fatalf("expected %q, but got %q", string(want), string(got))
+	}
+}
+
+func TestCrashHandler(t *testing.T) {
+	testCrashHandler(t, &crashTest{Cgo: false})
+}
+
+const crashSource = `
+package main
+
+import (
+	"fmt"
+	"runtime"
+)
+
+{{if .Cgo}}
+import "C"
+{{end}}
+
+func test(name string) {
+	defer func() {
+		if x := recover(); x != nil {
+			fmt.Printf(" recovered")
+		}
+		fmt.Printf(" done\n")
+	}()
+	fmt.Printf("%s:", name)
+	var s *string
+	_ = *s
+	fmt.Print("SHOULD NOT BE HERE")
+}
+
+func testInNewThread(name string) {
+	c := make(chan bool)
+	go func() {
+		runtime.LockOSThread()
+		test(name)
+		c <- true
+	}()
+	<-c
+}
+
+func main() {
+	runtime.LockOSThread()
+	test("main")
+	testInNewThread("new-thread")
+	testInNewThread("second-new-thread")
+	test("main-again")
+}
+`

src/pkg/runtime/os_windows.h

@@ -28,5 +28,7 @@ uint32 runtime·ctrlhandler(uint32 type);
 byte *runtime·compilecallback(Eface fn, bool cleanstack);
 void *runtime·callbackasm(void);
 
+void runtime·install_exception_handler(void);
+
 // TODO(brainman): should not need those
 #define	NSIG	65

src/pkg/runtime/proc.c

@@ -758,6 +758,11 @@ runtime·starttheworld(void)
 void
 runtime·mstart(void)
 {
+	// It is used by windows-386 only. Unfortunately, seh needs
+	// to be located on os stack, and mstart runs on os stack
+	// for both m0 and m.
+	SEH seh;
+
 	if(g != m->g0)
 		runtime·throw("bad runtime·mstart");
 
@@ -766,6 +771,7 @@ runtime·mstart(void)
 	// so other calls can reuse this stack space.
 	runtime·gosave(&m->g0->sched);
 	m->g0->sched.pc = (void*)-1;  // make sure it is never used
+	m->seh = &seh;
 	runtime·asminit();
 	runtime·minit();
 
@@ -775,6 +781,10 @@ runtime·mstart(void)
 		runtime·initsig();
 
 	schedule(nil);
+
+	// TODO(brainman): This point is never reached, because scheduler
+	// does not release os threads at the moment. But once this path
+	// is enabled, we must remove our seh here.
 }
 
 // When running with cgo, we call libcgo_thread_start

src/pkg/runtime/rt0_windows_386.s

@@ -3,11 +3,6 @@
 // license that can be found in the LICENSE file.
 
 TEXT _rt0_386_windows(SB),7,$0
-	// Set up SEH frame for bootstrap m
-	PUSHL	$runtime·sigtramp(SB)
-	PUSHL	0(FS)
-	MOVL	SP, 0(FS)
-
 	JMP	_rt0_386(SB)
 
 DATA  runtime·iswindows(SB)/4, $1

src/pkg/runtime/runtime.h

@@ -69,6 +69,7 @@ typedef	struct	Hchan		Hchan;
 typedef	struct	Complex64	Complex64;
 typedef	struct	Complex128	Complex128;
 typedef	struct	WinCall		WinCall;
+typedef	struct	SEH		SEH;
 typedef	struct	Timers		Timers;
 typedef	struct	Timer		Timer;
 typedef struct	GCStats		GCStats;
@@ -262,6 +263,7 @@ struct	M
 #ifdef GOOS_windows
 	void*	thread;		// thread handle
 #endif
+	SEH*	seh;
 	uintptr	end[];
 };
 
@@ -316,6 +318,11 @@ struct	WinCall
 	uintptr	r2;
 	uintptr	err;	// error number
 };
+struct	SEH
+{
+	void*	prev;
+	void*	handler;
+};
 
 #ifdef GOOS_windows
 enum {

src/pkg/runtime/sys_windows_386.s

@@ -243,11 +243,6 @@ TEXT runtime·tstart(SB),7,$0
 	MOVL	newm+4(SP), CX		// m
 	MOVL	m_g0(CX), DX		// g
 
-	// Set up SEH frame
-	PUSHL	$runtime·sigtramp(SB)
-	PUSHL	0(FS)
-	MOVL	SP, 0(FS)
-
 	// Layout new m scheduler stack on os stack.
 	MOVL	SP, AX
 	MOVL	AX, g_stackbase(DX)
@@ -267,11 +262,6 @@ TEXT runtime·tstart(SB),7,$0
 
 	CALL	runtime·mstart(SB)
 
-	// Pop SEH frame
-	MOVL	0(FS), SP
-	POPL	0(FS)
-	POPL	CX
-
 	RET
 
 // uint32 tstart_stdcall(M *newm);
@@ -296,3 +286,20 @@ TEXT runtime·setldt(SB),7,$0
 	MOVL	address+4(FP), CX
 	MOVL	CX, 0x14(FS)
 	RET
+
+// void install_exception_handler()
+TEXT runtime·install_exception_handler(SB),7,$0
+	get_tls(CX)
+	MOVL	m(CX), CX		// m
+
+	// Set up SEH frame
+	MOVL	m_seh(CX), DX
+	MOVL	$runtime·sigtramp(SB), AX
+	MOVL	AX, seh_handler(DX)
+	MOVL	0(FS), AX
+	MOVL	AX, seh_prev(DX)
+
+	// Install it
+	MOVL	DX, 0(FS)
+
+	RET

src/pkg/runtime/sys_windows_amd64.s

@@ -328,7 +328,6 @@ TEXT runtime·tstart_stdcall(SB),7,$0
 	// Someday the convention will be D is always cleared.
 	CLD
 
-	CALL	runtime·setstacklimits(SB)
 	CALL	runtime·stackcheck(SB)	// clobbers AX,CX
 	CALL	runtime·mstart(SB)
 
@@ -337,6 +336,10 @@ TEXT runtime·tstart_stdcall(SB),7,$0
 
 // set tls base to DI
 TEXT runtime·settls(SB),7,$0
-	CALL	runtime·setstacklimits(SB)
 	MOVQ	DI, 0x28(GS)
 	RET
+
+// void install_exception_handler()
+TEXT runtime·install_exception_handler(SB),7,$0
+	CALL	runtime·setstacklimits(SB)
+	RET

src/pkg/runtime/thread_windows.c

@@ -208,6 +208,7 @@ runtime·newosproc(M *m, G *g, void *stk, void (*fn)(void))
 void
 runtime·minit(void)
 {
+	runtime·install_exception_handler();
 }
 
 int64