1// Copyright 2016 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5//go:build linux && race
6
7package race_test
8
9import (
10	"sync/atomic"
11	"syscall"
12	"testing"
13	"unsafe"
14)
15
16func TestAtomicMmap(t *testing.T) {
17	// Test that atomic operations work on "external" memory. Previously they crashed (#16206).
18	// Also do a sanity correctness check: under race detector atomic operations
19	// are implemented inside of race runtime.
20	mem, err := syscall.Mmap(-1, 0, 1<<20, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
21	if err != nil {
22		t.Fatalf("mmap failed: %v", err)
23	}
24	defer syscall.Munmap(mem)
25	a := (*uint64)(unsafe.Pointer(&mem[0]))
26	if *a != 0 {
27		t.Fatalf("bad atomic value: %v, want 0", *a)
28	}
29	atomic.AddUint64(a, 1)
30	if *a != 1 {
31		t.Fatalf("bad atomic value: %v, want 1", *a)
32	}
33	atomic.AddUint64(a, 1)
34	if *a != 2 {
35		t.Fatalf("bad atomic value: %v, want 2", *a)
36	}
37}
38
39func TestAtomicPageBoundary(t *testing.T) {
40	// Test that atomic access near (but not cross) a page boundary
41	// doesn't fault. See issue 60825.
42
43	// Mmap two pages of memory, and make the second page inaccessible,
44	// so we have an address at the end of a page.
45	pagesize := syscall.Getpagesize()
46	b, err := syscall.Mmap(0, 0, 2*pagesize, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
47	if err != nil {
48		t.Fatalf("mmap failed %s", err)
49	}
50	defer syscall.Munmap(b)
51	err = syscall.Mprotect(b[pagesize:], syscall.PROT_NONE)
52	if err != nil {
53		t.Fatalf("mprotect high failed %s\n", err)
54	}
55
56	// This should not fault.
57	a := (*uint32)(unsafe.Pointer(&b[pagesize-4]))
58	atomic.StoreUint32(a, 1)
59	if x := atomic.LoadUint32(a); x != 1 {
60		t.Fatalf("bad atomic value: %v, want 1", x)
61	}
62	if x := atomic.AddUint32(a, 1); x != 2 {
63		t.Fatalf("bad atomic value: %v, want 2", x)
64	}
65}
66