runtime: added go files for mips64 architecture support

Change-Id: Ia496470e48b3c5d39fb9fef99fac356dfb73a949
Reviewed-on: https://go-review.googlesource.com/14927Reviewed-by: Minux Ma <minux@golang.org>

src/runtime/arch_mips64.go

+// Copyright 2015 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
+
+const (
+	thechar        = '0'
+	_BigEndian     = 1
+	_CacheLineSize = 32
+	_PhysPageSize  = 16384
+	_PCQuantum     = 4
+	_Int64Align    = 8
+	hugePageSize   = 0
+	minFrameSize   = 8
+)
+
+type uintreg uint64
+type intptr int64 // TODO(rsc): remove

src/runtime/arch_mips64le.go

+// Copyright 2015 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
+
+const (
+	thechar        = '0'
+	_BigEndian     = 0
+	_CacheLineSize = 32
+	_PhysPageSize  = 16384
+	_PCQuantum     = 4
+	_Int64Align    = 8
+	hugePageSize   = 0
+	minFrameSize   = 8
+)
+
+type uintreg uint64
+type intptr int64 // TODO(rsc): remove

src/runtime/sys_mips64x.go

+// Copyright 2015 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 mips64 mips64le
+
+package runtime
+
+import "unsafe"
+
+// adjust Gobuf as if it executed a call to fn with context ctxt
+// and then did an immediate Gosave.
+func gostartcall(buf *gobuf, fn, ctxt unsafe.Pointer) {
+	if buf.lr != 0 {
+		throw("invalid use of gostartcall")
+	}
+	buf.lr = buf.pc
+	buf.pc = uintptr(fn)
+	buf.ctxt = ctxt
+}
+
+// Called to rewind context saved during morestack back to beginning of function.
+// To help us, the linker emits a jmp back to the beginning right after the
+// call to morestack. We just have to decode and apply that jump.
+func rewindmorestack(buf *gobuf) {
+	var inst uint32
+	if buf.pc&3 == 0 && buf.pc != 0 {
+		inst = *(*uint32)(unsafe.Pointer(buf.pc))
+		if inst>>26 == 2 { // JMP addr
+			//print("runtime: rewind pc=", hex(buf.pc), " to pc=", hex(buf.pc &^ uintptr(1<<28-1) | uintptr((inst&^0xfc000000)<<2)), "\n");
+			buf.pc &^= 1<<28 - 1
+			buf.pc |= uintptr((inst &^ 0xfc000000) << 2)
+			return
+		}
+		if inst>>16 == 0x1000 { // BEQ	R0, R0, offset
+			//print("runtime: rewind pc=", hex(buf.pc), " to pc=", hex(buf.pc + uintptr(int32(int16(inst&0xffff))<<2 + 4)), "\n");
+			buf.pc += uintptr(int32(int16(inst&0xffff))<<2 + 4)
+			return
+		}
+	}
+	print("runtime: pc=", hex(buf.pc), " ", hex(inst), "\n")
+	throw("runtime: misuse of rewindmorestack")
+}