1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
// Copyright 2022 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 runtime_test
import (
"go/ast"
"go/build"
"go/importer"
"go/parser"
"go/printer"
"go/token"
"go/types"
"internal/testenv"
"os"
"regexp"
"runtime"
"strings"
"testing"
)
// Check that 64-bit fields on which we apply atomic operations
// are aligned to 8 bytes. This can be a problem on 32-bit systems.
func TestAtomicAlignment(t *testing.T) {
testenv.MustHaveGoBuild(t) // go command needed to resolve std .a files for importer.Default().
// Read the code making the tables above, to see which fields and
// variables we are currently checking.
checked := map[string]bool{}
x, err := os.ReadFile("./align_runtime_test.go")
if err != nil {
t.Fatalf("read failed: %v", err)
}
fieldDesc := map[int]string{}
r := regexp.MustCompile(`unsafe[.]Offsetof[(](\w+){}[.](\w+)[)]`)
matches := r.FindAllStringSubmatch(string(x), -1)
for i, v := range matches {
checked["field runtime."+v[1]+"."+v[2]] = true
fieldDesc[i] = v[1] + "." + v[2]
}
varDesc := map[int]string{}
r = regexp.MustCompile(`unsafe[.]Pointer[(]&(\w+)[)]`)
matches = r.FindAllStringSubmatch(string(x), -1)
for i, v := range matches {
checked["var "+v[1]] = true
varDesc[i] = v[1]
}
// Check all of our alignemnts. This is the actual core of the test.
for i, d := range runtime.AtomicFields {
if d%8 != 0 {
t.Errorf("field alignment of %s failed: offset is %d", fieldDesc[i], d)
}
}
for i, p := range runtime.AtomicVariables {
if uintptr(p)%8 != 0 {
t.Errorf("variable alignment of %s failed: address is %x", varDesc[i], p)
}
}
// The code above is the actual test. The code below attempts to check
// that the tables used by the code above are exhaustive.
// Parse the whole runtime package, checking that arguments of
// appropriate atomic operations are in the list above.
fset := token.NewFileSet()
m, err := parser.ParseDir(fset, ".", nil, 0)
if err != nil {
t.Fatalf("parsing runtime failed: %v", err)
}
pkg := m["runtime"] // Note: ignore runtime_test and main packages
// Filter files by those for the current architecture/os being tested.
fileMap := map[string]bool{}
for _, f := range buildableFiles(t, ".") {
fileMap[f] = true
}
var files []*ast.File
for fname, f := range pkg.Files {
if fileMap[fname] {
files = append(files, f)
}
}
// Call go/types to analyze the runtime package.
var info types.Info
info.Types = map[ast.Expr]types.TypeAndValue{}
conf := types.Config{Importer: importer.Default()}
_, err = conf.Check("runtime", fset, files, &info)
if err != nil {
t.Fatalf("typechecking runtime failed: %v", err)
}
// Analyze all atomic.*64 callsites.
v := Visitor{t: t, fset: fset, types: info.Types, checked: checked}
ast.Walk(&v, pkg)
}
type Visitor struct {
fset *token.FileSet
types map[ast.Expr]types.TypeAndValue
checked map[string]bool
t *testing.T
}
func (v *Visitor) Visit(n ast.Node) ast.Visitor {
c, ok := n.(*ast.CallExpr)
if !ok {
return v
}
f, ok := c.Fun.(*ast.SelectorExpr)
if !ok {
return v
}
p, ok := f.X.(*ast.Ident)
if !ok {
return v
}
if p.Name != "atomic" {
return v
}
if !strings.HasSuffix(f.Sel.Name, "64") {
return v
}
a := c.Args[0]
// This is a call to atomic.XXX64(a, ...). Make sure a is aligned to 8 bytes.
// XXX = one of Load, Store, Cas, etc.
// The arg we care about the alignment of is always the first one.
if u, ok := a.(*ast.UnaryExpr); ok && u.Op == token.AND {
v.checkAddr(u.X)
return v
}
// Other cases there's nothing we can check. Assume we're ok.
v.t.Logf("unchecked atomic operation %s %v", v.fset.Position(n.Pos()), v.print(n))
return v
}
// checkAddr checks to make sure n is a properly aligned address for a 64-bit atomic operation.
func (v *Visitor) checkAddr(n ast.Node) {
switch n := n.(type) {
case *ast.IndexExpr:
// Alignment of an array element is the same as the whole array.
v.checkAddr(n.X)
return
case *ast.Ident:
key := "var " + v.print(n)
if !v.checked[key] {
v.t.Errorf("unchecked variable %s %s", v.fset.Position(n.Pos()), key)
}
return
case *ast.SelectorExpr:
t := v.types[n.X].Type
if t == nil {
// Not sure what is happening here, go/types fails to
// type the selector arg on some platforms.
return
}
if p, ok := t.(*types.Pointer); ok {
// Note: we assume here that the pointer p in p.foo is properly
// aligned. We just check that foo is at a properly aligned offset.
t = p.Elem()
} else {
v.checkAddr(n.X)
}
if t.Underlying() == t {
v.t.Errorf("analysis can't handle unnamed type %s %v", v.fset.Position(n.Pos()), t)
}
key := "field " + t.String() + "." + n.Sel.Name
if !v.checked[key] {
v.t.Errorf("unchecked field %s %s", v.fset.Position(n.Pos()), key)
}
default:
v.t.Errorf("unchecked atomic address %s %v", v.fset.Position(n.Pos()), v.print(n))
}
}
func (v *Visitor) print(n ast.Node) string {
var b strings.Builder
printer.Fprint(&b, v.fset, n)
return b.String()
}
// buildableFiles returns the list of files in the given directory
// that are actually used for the build, given GOOS/GOARCH restrictions.
func buildableFiles(t *testing.T, dir string) []string {
ctxt := build.Default
ctxt.CgoEnabled = true
pkg, err := ctxt.ImportDir(dir, 0)
if err != nil {
t.Fatalf("can't find buildable files: %v", err)
}
return pkg.GoFiles
}
|
