sync/atomic: adjust for new runtime.cas64 prototype

R=golang-dev, minux.ma, josharian
CC=golang-dev
https://golang.org/cl/13859043

src/pkg/sync/atomic/asm_linux_arm.s

@@ -121,27 +121,32 @@ TEXT kernelCAS64<>(SB),NOSPLIT,$0-21
 	MOVW	R0, 20(FP)
 	RET
 
-TEXT generalCAS64<>(SB),NOSPLIT,$20-21
+TEXT ·generalCAS64(SB),NOSPLIT,$20-21
-	// bool runtime·cas64(uint64 volatile *addr, uint64 *old, uint64 new)
+	// bool runtime·cas64(uint64 volatile *addr, uint64 old, uint64 new)
 	MOVW	addr+0(FP), R0
+	// trigger potential paging fault here,
+	// because a fault in runtime.cas64 will hang.
+	MOVW	(R0), R2
 	// make unaligned atomic access panic
 	AND.S	$7, R0, R1
 	BEQ 	2(PC)
 	MOVW	R1, (R1)
 	MOVW	R0, 4(R13)
-	MOVW	$4(FP), R1 // oldval
+	MOVW	oldlo+4(FP), R1
 	MOVW	R1, 8(R13)
+	MOVW	oldhi+8(FP), R1
+	MOVW	R1, 12(R13)
 	MOVW	newlo+12(FP), R2
-	MOVW	R2, 12(R13)
+	MOVW	R2, 16(R13)
 	MOVW	newhi+16(FP), R3
-	MOVW	R3, 16(R13)
+	MOVW	R3, 20(R13)
 	BL  	runtime·cas64(SB)
-	MOVW	R0, 20(FP)
+	MOVB	R0, ret+20(FP)
 	RET
 
 GLOBL armCAS64(SB), $4
 
-TEXT setupAndCallCAS64<>(SB),NOSPLIT,$-21
+TEXT setupAndCallCAS64<>(SB),NOSPLIT,$-4-21
 	MOVW	$0xffff0ffc, R0 // __kuser_helper_version
 	MOVW	(R0), R0
 	// __kuser_cmpxchg64 only present if helper version >= 5
@@ -156,14 +161,14 @@ TEXT setupAndCallCAS64<>(SB),NOSPLIT,$-21
 	MOVW.CS	R1, armCAS64(SB)
 	MOVW.CS	R1, PC
 	// we are out of luck, can only use runtime's emulated 64-bit cas
-	MOVW	$generalCAS64<>(SB), R1
+	MOVW	$·generalCAS64(SB), R1
 	MOVW	R1, armCAS64(SB)
 	MOVW	R1, PC
 
 TEXT ·CompareAndSwapInt64(SB),NOSPLIT,$0
 	B   	·CompareAndSwapUint64(SB)
 
-TEXT ·CompareAndSwapUint64(SB),NOSPLIT,$-21
+TEXT ·CompareAndSwapUint64(SB),NOSPLIT,$-4-21
 	MOVW	armCAS64(SB), R0
 	CMP 	$0, R0
 	MOVW.NE	R0, PC

src/pkg/sync/atomic/atomic_linux_arm_test.go

@@ -0,0 +1,14 @@
+// Copyright 2013 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 atomic_test
+
+import (
+	. "sync/atomic"
+	"testing"
+)
+
+func TestGeneralCAS64(t *testing.T) {
+	testCompareAndSwapUint64(t, GeneralCAS64)
+}

src/pkg/sync/atomic/atomic_test.go

@@ -379,7 +379,7 @@ func TestCompareAndSwapInt64(t *testing.T) {
 	}
 }
 
-func TestCompareAndSwapUint64(t *testing.T) {
+func testCompareAndSwapUint64(t *testing.T, cas func(*uint64, uint64, uint64) bool) {
 	if test64err != nil {
 		t.Skipf("Skipping 64-bit tests: %v", test64err)
 	}
@@ -392,14 +392,14 @@ func TestCompareAndSwapUint64(t *testing.T) {
 	x.after = magic64
 	for val := uint64(1); val+val > val; val += val {
 		x.i = val
-		if !CompareAndSwapUint64(&x.i, val, val+1) {
+		if !cas(&x.i, val, val+1) {
 			t.Fatalf("should have swapped %#x %#x", val, val+1)
 		}
 		if x.i != val+1 {
 			t.Fatalf("wrong x.i after swap: x.i=%#x val+1=%#x", x.i, val+1)
 		}
 		x.i = val + 1
-		if CompareAndSwapUint64(&x.i, val, val+2) {
+		if cas(&x.i, val, val+2) {
 			t.Fatalf("should not have swapped %#x %#x", val, val+2)
 		}
 		if x.i != val+1 {
@@ -411,6 +411,10 @@ func TestCompareAndSwapUint64(t *testing.T) {
 	}
 }
 
+func TestCompareAndSwapUint64(t *testing.T) {
+	testCompareAndSwapUint64(t, CompareAndSwapUint64)
+}
+
 func TestCompareAndSwapUintptr(t *testing.T) {
 	var x struct {
 		before uintptr

src/pkg/sync/atomic/export_linux_arm_test.go

@@ -0,0 +1,9 @@
+// Copyright 2013 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 atomic
+
+func generalCAS64(*uint64, uint64, uint64) bool
+
+var GeneralCAS64 = generalCAS64