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// 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.
//go: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)
}
}
func TestAtomicPageBoundary(t *testing.T) {
// Test that atomic access near (but not cross) a page boundary
// doesn't fault. See issue 60825.
// Mmap two pages of memory, and make the second page inaccessible,
// so we have an address at the end of a page.
pagesize := syscall.Getpagesize()
b, err := syscall.Mmap(0, 0, 2*pagesize, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
if err != nil {
t.Fatalf("mmap failed %s", err)
}
defer syscall.Munmap(b)
err = syscall.Mprotect(b[pagesize:], syscall.PROT_NONE)
if err != nil {
t.Fatalf("mprotect high failed %s\n", err)
}
// This should not fault.
a := (*uint32)(unsafe.Pointer(&b[pagesize-4]))
atomic.StoreUint32(a, 1)
if x := atomic.LoadUint32(a); x != 1 {
t.Fatalf("bad atomic value: %v, want 1", x)
}
if x := atomic.AddUint32(a, 1); x != 2 {
t.Fatalf("bad atomic value: %v, want 2", x)
}
}
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