runtime: add linux/mips64x cgo support

Change-Id: Id40dd05b7b264f3b779fdf9ccc2421ba4bc70589
Reviewed-on: https://go-review.googlesource.com/19806Reviewed-by: Minux Ma <minux@golang.org>

src/runtime/asm_mips64x.s

@@ -31,7 +31,15 @@ TEXT runtime·rt0_go(SB),NOSPLIT,$0
 	MOVV	R1, (g_stack+stack_lo)(g)
 	MOVV	R29, (g_stack+stack_hi)(g)
 
-	// no cgo yet
+	// if there is a _cgo_init, call it using the gcc ABI.
+	MOVV	_cgo_init(SB), R25
+	BEQ	R25, nocgo
+
+	MOVV	R0, R7	// arg 3: not used
+	MOVV	R0, R6	// arg 2: not used
+	MOVV	$setg_gcc<>(SB), R5	// arg 1: setg
+	MOVV	g, R4	// arg 0: G
+	JAL	(R25)
 
 nocgo:
 	// update stackguard after _cgo_init
@@ -81,7 +89,7 @@ TEXT runtime·asminit(SB),NOSPLIT,$-8-0
 	RET
 
 TEXT _cgo_reginit(SB),NOSPLIT,$-8-0
-	// crosscall_ppc64 and crosscall2 need to reginit, but can't
+	// crosscall1 needs to reginit, but can't
 	// get at the 'runtime.reginit' symbol.
 	JMP	runtime·reginit(SB)
 
@@ -453,26 +461,64 @@ TEXT gosave<>(SB),NOSPLIT,$-8
 // aligned appropriately for the gcc ABI.
 // See cgocall.go for more details.
 TEXT ·asmcgocall(SB),NOSPLIT,$0-20
-	UNDEF	// no cgo yet
+	MOVV	fn+0(FP), R25
+	MOVV	arg+8(FP), R4
+
+	MOVV	R29, R3	// save original stack pointer
+	MOVV	g, R2
+
+	// Figure out if we need to switch to m->g0 stack.
+	// We get called to create new OS threads too, and those
+	// come in on the m->g0 stack already.
+	MOVV	g_m(g), R5
+	MOVV	m_g0(R5), R6
+	BEQ	R6, g, g0
+
+	JAL	gosave<>(SB)
+	MOVV	R6, g
+	JAL	runtime·save_g(SB)
+	MOVV	(g_sched+gobuf_sp)(g), R29
+
+	// Now on a scheduling stack (a pthread-created stack).
+g0:
+	// Save room for two of our pointers.
+	ADDV	$-16, R29
+	MOVV	R2, 0(R29)	// save old g on stack
+	MOVV	(g_stack+stack_hi)(R2), R2
+	SUBVU	R3, R2
+	MOVV	R2, 8(R29)	// save depth in old g stack (can't just save SP, as stack might be copied during a callback)
+	JAL	(R25)
+
+	// Restore g, stack pointer. R2 is return value.
+	MOVV	0(R29), g
+	JAL	runtime·save_g(SB)
+	MOVV	(g_stack+stack_hi)(g), R5
+	MOVV	8(R29), R6
+	SUBVU	R6, R5
+	MOVV	R5, R29
+
+	MOVW	R2, ret+16(FP)
 	RET
 
-// cgocallback(void (*fn)(void*), void *frame, uintptr framesize)
+// cgocallback(void (*fn)(void*), void *frame, uintptr framesize, uintptr ctxt)
 // Turn the fn into a Go func (by taking its address) and call
 // cgocallback_gofunc.
-TEXT runtime·cgocallback(SB),NOSPLIT,$24-24
+TEXT runtime·cgocallback(SB),NOSPLIT,$32-32
 	MOVV	$fn+0(FP), R1
 	MOVV	R1, 8(R29)
 	MOVV	frame+8(FP), R1
 	MOVV	R1, 16(R29)
 	MOVV	framesize+16(FP), R1
 	MOVV	R1, 24(R29)
+	MOVV	ctxt+24(FP), R1
+	MOVV	R1, 32(R29)
 	MOVV	$runtime·cgocallback_gofunc(SB), R1
 	JAL	(R1)
 	RET
 
-// cgocallback_gofunc(FuncVal*, void *frame, uintptr framesize)
+// cgocallback_gofunc(FuncVal*, void *frame, uintptr framesize, uintptr ctxt)
 // See cgocall.go for more details.
-TEXT ·cgocallback_gofunc(SB),NOSPLIT,$16-24
+TEXT ·cgocallback_gofunc(SB),NOSPLIT,$16-32
 	NO_LOCAL_POINTERS
 
 	// Load m and g from thread-local storage.
@@ -508,8 +554,8 @@ needm:
 	// and then systemstack will try to use it. If we don't set it here,
 	// that restored SP will be uninitialized (typically 0) and
 	// will not be usable.
-	MOVV	g_m(g), R1
-	MOVV	m_g0(R1), R1
+	MOVV	g_m(g), R3
+	MOVV	m_g0(R3), R1
 	MOVV	R29, (g_sched+gobuf_sp)(R1)
 
 havem:
@@ -537,18 +583,21 @@ havem:
 	// so that the traceback will seamlessly trace back into
 	// the earlier calls.
 	//
-	// In the new goroutine, -16(SP) and -8(SP) are unused.
+	// In the new goroutine, -8(SP) is unused (where SP refers to
+	// m->curg's SP while we're setting it up, before we've adjusted it).
 	MOVV	m_curg(R3), g
 	JAL	runtime·save_g(SB)
 	MOVV	(g_sched+gobuf_sp)(g), R2 // prepare stack as R2
-	MOVV	(g_sched+gobuf_pc)(g), R3
-	MOVV	R3, -24(R2)
+	MOVV	(g_sched+gobuf_pc)(g), R4
+	MOVV	R4, -24(R2)
+	MOVV    ctxt+24(FP), R1
+	MOVV    R1, -16(R2)
 	MOVV	$-24(R2), R29
 	JAL	runtime·cgocallbackg(SB)
 
 	// Restore g->sched (== m->curg->sched) from saved values.
-	MOVV	0(R29), R3
-	MOVV	R3, (g_sched+gobuf_pc)(g)
+	MOVV	0(R29), R4
+	MOVV	R4, (g_sched+gobuf_pc)(g)
 	MOVV	$24(R29), R2
 	MOVV	R2, (g_sched+gobuf_sp)(g)
 
@@ -580,10 +629,10 @@ TEXT runtime·setg(SB), NOSPLIT, $0-8
 	JAL	runtime·save_g(SB)
 	RET
 
-// void setg_gcc(G*); set g in C TLS.
-// Must obey the gcc calling convention.
-TEXT setg_gcc<>(SB),NOSPLIT,$-8-0
-	UNDEF	// no cgo yet
+// void setg_gcc(G*); set g called from gcc with g in R1
+TEXT setg_gcc<>(SB),NOSPLIT,$0-0
+	MOVV	R1, g
+	JAL	runtime·save_g(SB)
 	RET
 
 TEXT runtime·getcallerpc(SB),NOSPLIT,$8-16
@@ -805,8 +854,19 @@ TEXT runtime·return0(SB), NOSPLIT, $0
 
 // Called from cgo wrappers, this function returns g->m->curg.stack.hi.
 // Must obey the gcc calling convention.
-TEXT _cgo_topofstack(SB),NOSPLIT,$-8
-	UNDEF	// no cgo yet
+TEXT _cgo_topofstack(SB),NOSPLIT,$16
+	// g (R30) and REGTMP (R23)  might be clobbered by load_g. They
+	// are callee-save in the gcc calling convention, so save them.
+	MOVV	R23, savedR23-16(SP)
+	MOVV	g, savedG-8(SP)
+
+	JAL	runtime·load_g(SB)
+	MOVV	g_m(g), R1
+	MOVV	m_curg(R1), R1
+	MOVV	(g_stack+stack_hi)(R1), R2 // return value in R2
+
+	MOVV	savedG-8(SP), g
+	MOVV	savedR23-16(SP), R23
 	RET
 
 // The top-most function running on a goroutine

src/runtime/cgo_mips64x.go

+// Copyright 2016 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
+
+// crosscall1 calls into the runtime to set up the registers the
+// Go runtime expects and so the symbol it calls needs to be exported
+// for external linking to work.
+//go:cgo_export_static _cgo_reginit

src/runtime/cgocall.go

@@ -286,6 +286,10 @@ func cgocallbackg1(ctxt uintptr) {
 		// |                    | fixed frame area             |
 		// +--------------------+------------------------------+ <- sp
 		cb = (*args)(unsafe.Pointer(sp + 2*sys.MinFrameSize + 2*sys.PtrSize))
+	case "mips64", "mips64le":
+		// On mips64x, stack frame is two words and there's a saved LR between
+		// SP and the stack frame and between the stack frame and the arguments.
+		cb = (*args)(unsafe.Pointer(sp + 4*sys.PtrSize))
 	}
 
 	// Invoke callback.
@@ -323,7 +327,7 @@ func unwindm(restore *bool) {
 	switch GOARCH {
 	default:
 		throw("unwindm not implemented")
-	case "386", "amd64", "arm", "ppc64", "ppc64le", "s390x":
+	case "386", "amd64", "arm", "ppc64", "ppc64le", "mips64", "mips64le", "s390x":
 		sched.sp = *(*uintptr)(unsafe.Pointer(sched.sp + sys.MinFrameSize))
 	case "arm64":
 		sched.sp = *(*uintptr)(unsafe.Pointer(sched.sp + 16))

src/runtime/sys_linux_mips64x.s

@@ -228,8 +228,8 @@ TEXT runtime·sigfwd(SB),NOSPLIT,$0-32
 	MOVW	sig+8(FP), R4
 	MOVV	info+16(FP), R5
 	MOVV	ctx+24(FP), R6
-	MOVV	fn+0(FP), R1
-	JAL	(R1)
+	MOVV	fn+0(FP), R25
+	JAL	(R25)
 	RET
 
 TEXT runtime·sigtramp(SB),NOSPLIT,$64

src/runtime/tls_mips64x.s

@@ -16,8 +16,15 @@ TEXT runtime·save_g(SB),NOSPLIT,$-8-0
 	MOVB	runtime·iscgo(SB), R23
 	BEQ	R23, nocgo
 
+	MOVV	R3, R23	// save R3
+	MOVV	g, runtime·tls_g(SB) // TLS relocation clobbers R3
+	MOVV	R23, R3	// restore R3
+
 nocgo:
 	RET
 
 TEXT runtime·load_g(SB),NOSPLIT,$-8-0
+	MOVV	runtime·tls_g(SB), g // TLS relocation clobbers R3
 	RET
+
+GLOBL runtime·tls_g(SB), TLSBSS, $8