runtime: fix race atomic operations on external memory

The assembly is broken: it does `MOVQ g(R12), R14` expecting that
R12 contains tls address, but it does not do get_tls(R12) before.
This magically works on linux: `MOVQ g(R12), R14` is compiled to
`mov %fs:0xfffffffffffffff8,%r14` which does not use R12.
But it crashes on windows.

Add explicit `get_tls(R12)`.

Fixes #16206

Change-Id: Ic1f21a6fef2473bcf9147de6646929781c9c1e98
Reviewed-on: https://go-review.googlesource.com/24590
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

3 files changed, 84 insertions, 0 deletions

diff --git a/src/runtime/race/race_linux_test.go b/src/runtime/race/race_linux_test.go
new file mode 100644
index 0000000000..c00ce4d3df
--- /dev/null
+++ b/src/runtime/race/race_linux_test.go
@@ -0,0 +1,37 @@
+// 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 linux,race
+
+package race_test
+
+import (
+	"sync/atomic"
+	"syscall"
+	"testing"
+	"unsafe"
+)
+
+func TestAtomicMmap(t *testing.T) {
+	// Test that atomic operations work on "external" memory. Previously they crashed (#16206).
+	// Also do a sanity correctness check: under race detector atomic operations
+	// are implemented inside of race runtime.
+	mem, err := syscall.Mmap(-1, 0, 1<<20, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
+	if err != nil {
+		t.Fatalf("mmap failed: %v", err)
+	}
+	defer syscall.Munmap(mem)
+	a := (*uint64)(unsafe.Pointer(&mem[0]))
+	if *a != 0 {
+		t.Fatalf("bad atomic value: %v, want 0", *a)
+	}
+	atomic.AddUint64(a, 1)
+	if *a != 1 {
+		t.Fatalf("bad atomic value: %v, want 1", *a)
+	}
+	atomic.AddUint64(a, 1)
+	if *a != 2 {
+		t.Fatalf("bad atomic value: %v, want 2", *a)
+	}
+}
diff --git a/src/runtime/race/race_windows_test.go b/src/runtime/race/race_windows_test.go
new file mode 100644
index 0000000000..307a1ea6c0
--- /dev/null
+++ b/src/runtime/race/race_windows_test.go
@@ -0,0 +1,46 @@
+// 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 windows,race
+
+package race_test
+
+import (
+	"sync/atomic"
+	"syscall"
+	"testing"
+	"unsafe"
+)
+
+func TestAtomicMmap(t *testing.T) {
+	// Test that atomic operations work on "external" memory. Previously they crashed (#16206).
+	// Also do a sanity correctness check: under race detector atomic operations
+	// are implemented inside of race runtime.
+	kernel32 := syscall.NewLazyDLL("kernel32.dll")
+	VirtualAlloc := kernel32.NewProc("VirtualAlloc")
+	VirtualFree := kernel32.NewProc("VirtualFree")
+	const (
+		MEM_COMMIT     = 0x00001000
+		MEM_RESERVE    = 0x00002000
+		MEM_RELEASE    = 0x8000
+		PAGE_READWRITE = 0x04
+	)
+	mem, _, err := syscall.Syscall6(VirtualAlloc.Addr(), 4, 0, 1<<20, MEM_COMMIT|MEM_RESERVE, PAGE_READWRITE, 0, 0)
+	if err != 0 {
+		t.Fatalf("VirtualAlloc failed: %v", err)
+	}
+	defer syscall.Syscall(VirtualFree.Addr(), 3, mem, 1<<20, MEM_RELEASE)
+	a := (*uint64)(unsafe.Pointer(mem))
+	if *a != 0 {
+		t.Fatalf("bad atomic value: %v, want 0", *a)
+	}
+	atomic.AddUint64(a, 1)
+	if *a != 1 {
+		t.Fatalf("bad atomic value: %v, want 1", *a)
+	}
+	atomic.AddUint64(a, 1)
+	if *a != 2 {
+		t.Fatalf("bad atomic value: %v, want 2", *a)
+	}
+}
diff --git a/src/runtime/race_amd64.s b/src/runtime/race_amd64.s
index 94ca76da27..cc1d92f437 100644
--- a/src/runtime/race_amd64.s
+++ b/src/runtime/race_amd64.s
@@ -338,6 +338,7 @@ racecallatomic_ignore:
 	// An attempt to synchronize on the address would cause crash.
 	MOVQ	AX, R15	// remember the original function
 	MOVQ	$__tsan_go_ignore_sync_begin(SB), AX
+	get_tls(R12)
 	MOVQ	g(R12), R14
 	MOVQ	g_racectx(R14), RARG0	// goroutine context
 	CALL	racecall<>(SB)