race_linux_test.go

     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  
     7  package race_test
     8  
     9  import (
    10  	"sync/atomic"
    11  	"syscall"
    12  	"testing"
    13  	"unsafe"
    14  )
    15  
    16  func 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  
    39  func 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
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