diff --git a/src/runtime/defs_plan9_386.go b/src/runtime/defs_plan9_386.go
index 212ecdf14a..3574cb6654 100644
--- a/src/runtime/defs_plan9_386.go
+++ b/src/runtime/defs_plan9_386.go
@@ -23,3 +23,29 @@ type ureg struct {
 	sp    uint32
 	ss    uint32 /* old stack segment */
 }
+
+type sigctxt struct {
+	u *ureg
+}
+
+func (c *sigctxt) pc() uintptr { return uintptr(c.u.pc) }
+func (c *sigctxt) sp() uintptr { return uintptr(c.u.sp) }
+
+func (c *sigctxt) setpc(x uintptr) { c.u.pc = uint32(x) }
+func (c *sigctxt) setsp(x uintptr) { c.u.sp = uint32(x) }
+
+func dumpregs(u *ureg) {
+	print("ax    ", hex(u.ax), "\n")
+	print("bx    ", hex(u.bx), "\n")
+	print("cx    ", hex(u.cx), "\n")
+	print("dx    ", hex(u.dx), "\n")
+	print("di    ", hex(u.di), "\n")
+	print("si    ", hex(u.si), "\n")
+	print("bp    ", hex(u.bp), "\n")
+	print("sp    ", hex(u.sp), "\n")
+	print("pc    ", hex(u.pc), "\n")
+	print("flags ", hex(u.flags), "\n")
+	print("cs    ", hex(u.cs), "\n")
+	print("fs    ", hex(u.fs), "\n")
+	print("gs    ", hex(u.gs), "\n")
+}
diff --git a/src/runtime/defs_plan9_amd64.go b/src/runtime/defs_plan9_amd64.go
index 510da0e994..54b4d39076 100644
--- a/src/runtime/defs_plan9_amd64.go
+++ b/src/runtime/defs_plan9_amd64.go
@@ -32,3 +32,37 @@ type ureg struct {
 	sp    uint64 /* sp */
 	ss    uint64 /* old stack segment */
 }
+
+type sigctxt struct {
+	u *ureg
+}
+
+func (c *sigctxt) pc() uintptr { return uintptr(c.u.ip) }
+func (c *sigctxt) sp() uintptr { return uintptr(c.u.sp) }
+
+func (c *sigctxt) setpc(x uintptr) { c.u.ip = uint64(x) }
+func (c *sigctxt) setsp(x uintptr) { c.u.sp = uint64(x) }
+
+func dumpregs(u *ureg) {
+	print("ax    ", hex(u.ax), "\n")
+	print("bx    ", hex(u.bx), "\n")
+	print("cx    ", hex(u.cx), "\n")
+	print("dx    ", hex(u.dx), "\n")
+	print("di    ", hex(u.di), "\n")
+	print("si    ", hex(u.si), "\n")
+	print("bp    ", hex(u.bp), "\n")
+	print("sp    ", hex(u.sp), "\n")
+	print("r8    ", hex(u.r8), "\n")
+	print("r9    ", hex(u.r9), "\n")
+	print("r10   ", hex(u.r10), "\n")
+	print("r11   ", hex(u.r11), "\n")
+	print("r12   ", hex(u.r12), "\n")
+	print("r13   ", hex(u.r13), "\n")
+	print("r14   ", hex(u.r14), "\n")
+	print("r15   ", hex(u.r15), "\n")
+	print("ip    ", hex(u.ip), "\n")
+	print("flags ", hex(u.flags), "\n")
+	print("cs    ", hex(u.cs), "\n")
+	print("fs    ", hex(u.fs), "\n")
+	print("gs    ", hex(u.gs), "\n")
+}
diff --git a/src/runtime/os_plan9_386.go b/src/runtime/os3_plan9.go
similarity index 76%
rename from src/runtime/os_plan9_386.go
rename to src/runtime/os3_plan9.go
index 7dda13931e..58ca0e7b2f 100644
--- a/src/runtime/os_plan9_386.go
+++ b/src/runtime/os3_plan9.go
@@ -6,22 +6,6 @@ package runtime
 
 import "unsafe"
 
-func dumpregs(u *ureg) {
-	print("ax    ", hex(u.ax), "\n")
-	print("bx    ", hex(u.bx), "\n")
-	print("cx    ", hex(u.cx), "\n")
-	print("dx    ", hex(u.dx), "\n")
-	print("di    ", hex(u.di), "\n")
-	print("si    ", hex(u.si), "\n")
-	print("bp    ", hex(u.bp), "\n")
-	print("sp    ", hex(u.sp), "\n")
-	print("pc    ", hex(u.pc), "\n")
-	print("flags ", hex(u.flags), "\n")
-	print("cs    ", hex(u.cs), "\n")
-	print("fs    ", hex(u.fs), "\n")
-	print("gs    ", hex(u.gs), "\n")
-}
-
 func sighandler(_ureg *ureg, note *byte, gp *g) int {
 	_g_ := getg()
 	var t sigTabT
@@ -30,6 +14,8 @@ func sighandler(_ureg *ureg, note *byte, gp *g) int {
 	var sig int
 	var flags int
 
+	c := &sigctxt{_ureg}
+
 	// The kernel will never pass us a nil note or ureg so we probably
 	// made a mistake somewhere in sigtramp.
 	if _ureg == nil || note == nil {
@@ -65,24 +51,24 @@ func sighandler(_ureg *ureg, note *byte, gp *g) int {
 		// we can reliably access it from the panic routines.
 		memmove(unsafe.Pointer(_g_.m.notesig), unsafe.Pointer(note), uintptr(length+1))
 		gp.sig = uint32(sig)
-		gp.sigpc = uintptr(_ureg.pc)
+		gp.sigpc = c.pc()
 		// Only push sigpanic if PC != 0.
 		//
 		// If PC == 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 sigpanic instead. (Otherwise the trace will end at
 		// sigpanic and we won't get to see who faulted).
-		if _ureg.pc != 0 {
-			sp := _ureg.sp
+		if c.pc() != 0 {
+			sp := c.sp()
 			if regSize > ptrSize {
 				sp -= ptrSize
-				*(*uintptr)(unsafe.Pointer(uintptr(sp))) = 0
+				*(*uintptr)(unsafe.Pointer(sp)) = 0
 			}
 			sp -= ptrSize
-			*(*uintptr)(unsafe.Pointer(uintptr(sp))) = uintptr(_ureg.pc)
-			_ureg.sp = sp
+			*(*uintptr)(unsafe.Pointer(sp)) = c.pc()
+			c.setsp(sp)
 		}
-		_ureg.pc = uint32(funcPC(sigpanic))
+		c.setpc(funcPC(sigpanic))
 		return _NCONT
 	}
 	if flags&_SigNotify != 0 {
@@ -101,11 +87,11 @@ Throw:
 	_g_.m.caughtsig = gp
 	startpanic()
 	print(gostringnocopy(note), "\n")
-	print("PC=", hex(_ureg.pc), "\n")
+	print("PC=", hex(c.pc()), "\n")
 	print("\n")
 	if gotraceback(&docrash) > 0 {
 		goroutineheader(gp)
-		tracebacktrap(uintptr(_ureg.pc), uintptr(_ureg.sp), 0, gp)
+		tracebacktrap(c.pc(), c.sp(), 0, gp)
 		tracebackothers(gp)
 		print("\n")
 		dumpregs(_ureg)
diff --git a/src/runtime/os_plan9_amd64.go b/src/runtime/os_plan9_amd64.go
deleted file mode 100644
index 8727dcc20f..0000000000
--- a/src/runtime/os_plan9_amd64.go
+++ /dev/null
@@ -1,139 +0,0 @@
-// Copyright 2010 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 dumpregs(u *ureg) {
-	print("ax    ", hex(u.ax), "\n")
-	print("bx    ", hex(u.bx), "\n")
-	print("cx    ", hex(u.cx), "\n")
-	print("dx    ", hex(u.dx), "\n")
-	print("di    ", hex(u.di), "\n")
-	print("si    ", hex(u.si), "\n")
-	print("bp    ", hex(u.bp), "\n")
-	print("sp    ", hex(u.sp), "\n")
-	print("r8    ", hex(u.r8), "\n")
-	print("r9    ", hex(u.r9), "\n")
-	print("r10   ", hex(u.r10), "\n")
-	print("r11   ", hex(u.r11), "\n")
-	print("r12   ", hex(u.r12), "\n")
-	print("r13   ", hex(u.r13), "\n")
-	print("r14   ", hex(u.r14), "\n")
-	print("r15   ", hex(u.r15), "\n")
-	print("ip    ", hex(u.ip), "\n")
-	print("flags ", hex(u.flags), "\n")
-	print("cs    ", hex(uint64(u.cs)), "\n")
-	print("fs    ", hex(uint64(u.fs)), "\n")
-	print("gs    ", hex(uint64(u.gs)), "\n")
-}
-
-func sighandler(_ureg *ureg, note *byte, gp *g) int {
-	_g_ := getg()
-	var t sigTabT
-	var docrash bool
-	var length int
-	var sig int
-	var flags int
-
-	// The kernel will never pass us a nil note or ureg so we probably
-	// made a mistake somewhere in sigtramp.
-	if _ureg == nil || note == nil {
-		print("sighandler: ureg ", _ureg, " note ", note, "\n")
-		goto Throw
-	}
-	// Check that the note is no more than ERRMAX bytes (including
-	// the trailing NUL). We should never receive a longer note.
-	length = findnull(note)
-	if length > _ERRMAX-1 {
-		print("sighandler: note is longer than ERRMAX\n")
-		goto Throw
-	}
-	// See if the note matches one of the patterns in sigtab.
-	// Notes that do not match any pattern can be handled at a higher
-	// level by the program but will otherwise be ignored.
-	flags = _SigNotify
-	for sig, t = range sigtable {
-		n := len(t.name)
-		if length < n {
-			continue
-		}
-		if strncmp(note, &t.name[0], uintptr(n)) == 0 {
-			flags = t.flags
-			break
-		}
-	}
-	if flags&_SigGoExit != 0 {
-		exits((*byte)(add(unsafe.Pointer(note), 9))) // Strip "go: exit " prefix.
-	}
-	if flags&_SigPanic != 0 {
-		// Copy the error string from sigtramp's stack into m->notesig so
-		// we can reliably access it from the panic routines.
-		memmove(unsafe.Pointer(_g_.m.notesig), unsafe.Pointer(note), uintptr(length+1))
-		gp.sig = uint32(sig)
-		gp.sigpc = uintptr(_ureg.ip)
-		// Only push sigpanic if PC != 0.
-		//
-		// If PC == 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 sigpanic instead. (Otherwise the trace will end at
-		// sigpanic and we won't get to see who faulted).
-		if _ureg.ip != 0 {
-			sp := _ureg.sp
-			if regSize > ptrSize {
-				sp -= ptrSize
-				*(*uintptr)(unsafe.Pointer(uintptr(sp))) = 0
-			}
-			sp -= ptrSize
-			*(*uintptr)(unsafe.Pointer(uintptr(sp))) = uintptr(_ureg.ip)
-			_ureg.sp = sp
-		}
-		_ureg.ip = uint64(funcPC(sigpanic))
-		return _NCONT
-	}
-	if flags&_SigNotify != 0 {
-		// TODO(ality): See if os/signal wants it.
-		//if(sigsend(...))
-		//	return _NCONT;
-	}
-	if flags&_SigKill != 0 {
-		goto Exit
-	}
-	if flags&_SigThrow == 0 {
-		return _NCONT
-	}
-Throw:
-	_g_.m.throwing = 1
-	_g_.m.caughtsig = gp
-	startpanic()
-	print(gostringnocopy(note), "\n")
-	print("PC=", hex(_ureg.ip), "\n")
-	print("\n")
-	if gotraceback(&docrash) > 0 {
-		goroutineheader(gp)
-		tracebacktrap(uintptr(_ureg.ip), uintptr(_ureg.sp), 0, gp)
-		tracebackothers(gp)
-		print("\n")
-		dumpregs(_ureg)
-	}
-	if docrash {
-		crash()
-	}
-Exit:
-	goexitsall(note)
-	exits(note)
-	return _NDFLT // not reached
-}
-
-func sigenable(sig uint32) {
-}
-
-func sigdisable(sig uint32) {
-}
-
-func resetcpuprofiler(hz int32) {
-	// TODO: Enable profiling interrupts.
-	getg().m.profilehz = hz
-}