runtime: make windows exception handler code arch independent

Mainly it is simple copy. But I had to change amd64
lastcontinuehandler return value from uint32 to int32.
I don't remember how it happened to be uint32, but new
int32 is matching better with Windows documentation (LONG).
I don't think it matters one way or the others.

Change-Id: I6935224a2470ad6301e27590f2baa86c13bbe8d5
Reviewed-on: https://go-review.googlesource.com/8686
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

1 files changed, 117 insertions, 0 deletions

diff --git a/src/runtime/signal_windows.go b/src/runtime/signal_windows.go
new file mode 100644
index 0000000000..ab8fe206c7
--- /dev/null
+++ b/src/runtime/signal_windows.go
@@ -0,0 +1,117 @@
+// Copyright 2011 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
+
+import (
+	"unsafe"
+)
+
+func isgoexception(info *exceptionrecord, r *context) bool {
+	// Only handle exception if executing instructions in Go binary
+	// (not Windows library code).
+	if r.ip() < themoduledata.text || themoduledata.etext < r.ip() {
+		return false
+	}
+
+	if issigpanic(info.exceptioncode) == 0 {
+		return false
+	}
+
+	return true
+}
+
+// Called by sigtramp from Windows VEH handler.
+// Return value signals whether the exception has been handled (EXCEPTION_CONTINUE_EXECUTION)
+// or should be made available to other handlers in the chain (EXCEPTION_CONTINUE_SEARCH).
+
+func exceptionhandler(info *exceptionrecord, r *context, gp *g) int32 {
+	if !isgoexception(info, r) {
+		return _EXCEPTION_CONTINUE_SEARCH
+	}
+
+	// Make it look like a call to the signal func.
+	// Have to pass arguments out of band since
+	// augmenting the stack frame would break
+	// the unwinding code.
+	gp.sig = info.exceptioncode
+	gp.sigcode0 = uintptr(info.exceptioninformation[0])
+	gp.sigcode1 = uintptr(info.exceptioninformation[1])
+	gp.sigpc = r.ip()
+
+	// Only push runtime·sigpanic if r.ip() != 0.
+	// If r.ip() == 0, probably panicked because of a
+	// call to a nil func.  Not pushing that onto sp will
+	// make the trace look like a call to runtime·sigpanic instead.
+	// (Otherwise the trace will end at runtime·sigpanic and we
+	// won't get to see who faulted.)
+	if r.ip() != 0 {
+		sp := unsafe.Pointer(r.sp())
+		sp = add(sp, ^uintptr(unsafe.Sizeof(uintptr(0))-1)) // sp--
+		*((*uintptr)(sp)) = r.ip()
+		r.setsp(uintptr(sp))
+	}
+	r.setip(funcPC(sigpanic))
+	return _EXCEPTION_CONTINUE_EXECUTION
+}
+
+// It seems Windows searches ContinueHandler's list even
+// if ExceptionHandler returns EXCEPTION_CONTINUE_EXECUTION.
+// firstcontinuehandler will stop that search,
+// if exceptionhandler did the same earlier.
+func firstcontinuehandler(info *exceptionrecord, r *context, gp *g) int32 {
+	if !isgoexception(info, r) {
+		return _EXCEPTION_CONTINUE_SEARCH
+	}
+	return _EXCEPTION_CONTINUE_EXECUTION
+}
+
+var testingWER bool
+
+// lastcontinuehandler is reached, because runtime cannot handle
+// current exception. lastcontinuehandler will print crash info and exit.
+func lastcontinuehandler(info *exceptionrecord, r *context, gp *g) int32 {
+	if testingWER {
+		return _EXCEPTION_CONTINUE_SEARCH
+	}
+
+	_g_ := getg()
+
+	if panicking != 0 { // traceback already printed
+		exit(2)
+	}
+	panicking = 1
+
+	print("Exception ", hex(info.exceptioncode), " ", hex(info.exceptioninformation[0]), " ", hex(info.exceptioninformation[1]), " ", hex(r.ip()), "\n")
+
+	print("PC=", hex(r.ip()), "\n")
+	if _g_.m.lockedg != nil && _g_.m.ncgo > 0 && gp == _g_.m.g0 {
+		print("signal arrived during cgo execution\n")
+		gp = _g_.m.lockedg
+	}
+	print("\n")
+
+	var docrash bool
+	if gotraceback(&docrash) > 0 {
+		tracebacktrap(r.ip(), r.sp(), 0, gp)
+		tracebackothers(gp)
+		dumpregs(r)
+	}
+
+	if docrash {
+		crash()
+	}
+
+	exit(2)
+	return 0 // not reached
+}
+
+func sigenable(sig uint32) {
+}
+
+func sigdisable(sig uint32) {
+}
+
+func sigignore(sig uint32) {
+}