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-rw-r--r--src/cmd/link/elf_test.go424
1 files changed, 424 insertions, 0 deletions
diff --git a/src/cmd/link/elf_test.go b/src/cmd/link/elf_test.go
new file mode 100644
index 0000000..20754d0
--- /dev/null
+++ b/src/cmd/link/elf_test.go
@@ -0,0 +1,424 @@
+// Copyright 2019 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 dragonfly freebsd linux netbsd openbsd
+
+package main
+
+import (
+ "cmd/internal/sys"
+ "debug/elf"
+ "fmt"
+ "internal/testenv"
+ "io/ioutil"
+ "os"
+ "os/exec"
+ "path/filepath"
+ "runtime"
+ "strings"
+ "sync"
+ "testing"
+ "text/template"
+)
+
+func getCCAndCCFLAGS(t *testing.T, env []string) (string, []string) {
+ goTool := testenv.GoToolPath(t)
+ cmd := exec.Command(goTool, "env", "CC")
+ cmd.Env = env
+ ccb, err := cmd.Output()
+ if err != nil {
+ t.Fatal(err)
+ }
+ cc := strings.TrimSpace(string(ccb))
+
+ cmd = exec.Command(goTool, "env", "GOGCCFLAGS")
+ cmd.Env = env
+ cflagsb, err := cmd.Output()
+ if err != nil {
+ t.Fatal(err)
+ }
+ cflags := strings.Fields(string(cflagsb))
+
+ return cc, cflags
+}
+
+var asmSource = `
+ .section .text1,"ax"
+s1:
+ .byte 0
+ .section .text2,"ax"
+s2:
+ .byte 0
+`
+
+var goSource = `
+package main
+func main() {}
+`
+
+// The linker used to crash if an ELF input file had multiple text sections
+// with the same name.
+func TestSectionsWithSameName(t *testing.T) {
+ testenv.MustHaveGoBuild(t)
+ testenv.MustHaveCGO(t)
+ t.Parallel()
+
+ objcopy, err := exec.LookPath("objcopy")
+ if err != nil {
+ t.Skipf("can't find objcopy: %v", err)
+ }
+
+ dir, err := ioutil.TempDir("", "go-link-TestSectionsWithSameName")
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer os.RemoveAll(dir)
+
+ gopath := filepath.Join(dir, "GOPATH")
+ env := append(os.Environ(), "GOPATH="+gopath)
+
+ if err := ioutil.WriteFile(filepath.Join(dir, "go.mod"), []byte("module elf_test\n"), 0666); err != nil {
+ t.Fatal(err)
+ }
+
+ asmFile := filepath.Join(dir, "x.s")
+ if err := ioutil.WriteFile(asmFile, []byte(asmSource), 0444); err != nil {
+ t.Fatal(err)
+ }
+
+ goTool := testenv.GoToolPath(t)
+ cc, cflags := getCCAndCCFLAGS(t, env)
+
+ asmObj := filepath.Join(dir, "x.o")
+ t.Logf("%s %v -c -o %s %s", cc, cflags, asmObj, asmFile)
+ if out, err := exec.Command(cc, append(cflags, "-c", "-o", asmObj, asmFile)...).CombinedOutput(); err != nil {
+ t.Logf("%s", out)
+ t.Fatal(err)
+ }
+
+ asm2Obj := filepath.Join(dir, "x2.syso")
+ t.Logf("%s --rename-section .text2=.text1 %s %s", objcopy, asmObj, asm2Obj)
+ if out, err := exec.Command(objcopy, "--rename-section", ".text2=.text1", asmObj, asm2Obj).CombinedOutput(); err != nil {
+ t.Logf("%s", out)
+ t.Fatal(err)
+ }
+
+ for _, s := range []string{asmFile, asmObj} {
+ if err := os.Remove(s); err != nil {
+ t.Fatal(err)
+ }
+ }
+
+ goFile := filepath.Join(dir, "main.go")
+ if err := ioutil.WriteFile(goFile, []byte(goSource), 0444); err != nil {
+ t.Fatal(err)
+ }
+
+ cmd := exec.Command(goTool, "build")
+ cmd.Dir = dir
+ cmd.Env = env
+ t.Logf("%s build", goTool)
+ if out, err := cmd.CombinedOutput(); err != nil {
+ t.Logf("%s", out)
+ t.Fatal(err)
+ }
+}
+
+var cSources35779 = []string{`
+static int blah() { return 42; }
+int Cfunc1() { return blah(); }
+`, `
+static int blah() { return 42; }
+int Cfunc2() { return blah(); }
+`,
+}
+
+// TestMinusRSymsWithSameName tests a corner case in the new
+// loader. Prior to the fix this failed with the error 'loadelf:
+// $WORK/b001/_pkg_.a(ldr.syso): duplicate symbol reference: blah in
+// both main(.text) and main(.text)'. See issue #35779.
+func TestMinusRSymsWithSameName(t *testing.T) {
+ testenv.MustHaveGoBuild(t)
+ testenv.MustHaveCGO(t)
+ t.Parallel()
+
+ dir, err := ioutil.TempDir("", "go-link-TestMinusRSymsWithSameName")
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer os.RemoveAll(dir)
+
+ gopath := filepath.Join(dir, "GOPATH")
+ env := append(os.Environ(), "GOPATH="+gopath)
+
+ if err := ioutil.WriteFile(filepath.Join(dir, "go.mod"), []byte("module elf_test\n"), 0666); err != nil {
+ t.Fatal(err)
+ }
+
+ goTool := testenv.GoToolPath(t)
+ cc, cflags := getCCAndCCFLAGS(t, env)
+
+ objs := []string{}
+ csrcs := []string{}
+ for i, content := range cSources35779 {
+ csrcFile := filepath.Join(dir, fmt.Sprintf("x%d.c", i))
+ csrcs = append(csrcs, csrcFile)
+ if err := ioutil.WriteFile(csrcFile, []byte(content), 0444); err != nil {
+ t.Fatal(err)
+ }
+
+ obj := filepath.Join(dir, fmt.Sprintf("x%d.o", i))
+ objs = append(objs, obj)
+ t.Logf("%s %v -c -o %s %s", cc, cflags, obj, csrcFile)
+ if out, err := exec.Command(cc, append(cflags, "-c", "-o", obj, csrcFile)...).CombinedOutput(); err != nil {
+ t.Logf("%s", out)
+ t.Fatal(err)
+ }
+ }
+
+ sysoObj := filepath.Join(dir, "ldr.syso")
+ t.Logf("%s %v -nostdlib -r -o %s %v", cc, cflags, sysoObj, objs)
+ if out, err := exec.Command(cc, append(cflags, "-nostdlib", "-r", "-o", sysoObj, objs[0], objs[1])...).CombinedOutput(); err != nil {
+ t.Logf("%s", out)
+ t.Fatal(err)
+ }
+
+ cruft := [][]string{objs, csrcs}
+ for _, sl := range cruft {
+ for _, s := range sl {
+ if err := os.Remove(s); err != nil {
+ t.Fatal(err)
+ }
+ }
+ }
+
+ goFile := filepath.Join(dir, "main.go")
+ if err := ioutil.WriteFile(goFile, []byte(goSource), 0444); err != nil {
+ t.Fatal(err)
+ }
+
+ t.Logf("%s build", goTool)
+ cmd := exec.Command(goTool, "build")
+ cmd.Dir = dir
+ cmd.Env = env
+ if out, err := cmd.CombinedOutput(); err != nil {
+ t.Logf("%s", out)
+ t.Fatal(err)
+ }
+}
+
+const pieSourceTemplate = `
+package main
+
+import "fmt"
+
+// Force the creation of a lot of type descriptors that will go into
+// the .data.rel.ro section.
+{{range $index, $element := .}}var V{{$index}} interface{} = [{{$index}}]int{}
+{{end}}
+
+func main() {
+{{range $index, $element := .}} fmt.Println(V{{$index}})
+{{end}}
+}
+`
+
+func TestPIESize(t *testing.T) {
+ testenv.MustHaveGoBuild(t)
+
+ // We don't want to test -linkmode=external if cgo is not supported.
+ // On some systems -buildmode=pie implies -linkmode=external, so just
+ // always skip the test if cgo is not supported.
+ testenv.MustHaveCGO(t)
+
+ if !sys.BuildModeSupported(runtime.Compiler, "pie", runtime.GOOS, runtime.GOARCH) {
+ t.Skip("-buildmode=pie not supported")
+ }
+
+ t.Parallel()
+
+ tmpl := template.Must(template.New("pie").Parse(pieSourceTemplate))
+
+ writeGo := func(t *testing.T, dir string) {
+ f, err := os.Create(filepath.Join(dir, "pie.go"))
+ if err != nil {
+ t.Fatal(err)
+ }
+
+ // Passing a 100-element slice here will cause
+ // pieSourceTemplate to create 100 variables with
+ // different types.
+ if err := tmpl.Execute(f, make([]byte, 100)); err != nil {
+ t.Fatal(err)
+ }
+
+ if err := f.Close(); err != nil {
+ t.Fatal(err)
+ }
+ }
+
+ for _, external := range []bool{false, true} {
+ external := external
+
+ name := "TestPieSize-"
+ if external {
+ name += "external"
+ } else {
+ name += "internal"
+ }
+ t.Run(name, func(t *testing.T) {
+ t.Parallel()
+
+ dir, err := ioutil.TempDir("", "go-link-"+name)
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer os.RemoveAll(dir)
+
+ writeGo(t, dir)
+
+ binexe := filepath.Join(dir, "exe")
+ binpie := filepath.Join(dir, "pie")
+ if external {
+ binexe += "external"
+ binpie += "external"
+ }
+
+ build := func(bin, mode string) error {
+ cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", bin, "-buildmode="+mode)
+ if external {
+ cmd.Args = append(cmd.Args, "-ldflags=-linkmode=external")
+ }
+ cmd.Args = append(cmd.Args, "pie.go")
+ cmd.Dir = dir
+ t.Logf("%v", cmd.Args)
+ out, err := cmd.CombinedOutput()
+ if len(out) > 0 {
+ t.Logf("%s", out)
+ }
+ if err != nil {
+ t.Error(err)
+ }
+ return err
+ }
+
+ var errexe, errpie error
+ var wg sync.WaitGroup
+ wg.Add(2)
+ go func() {
+ defer wg.Done()
+ errexe = build(binexe, "exe")
+ }()
+ go func() {
+ defer wg.Done()
+ errpie = build(binpie, "pie")
+ }()
+ wg.Wait()
+ if errexe != nil || errpie != nil {
+ t.Fatal("link failed")
+ }
+
+ var sizeexe, sizepie uint64
+ if fi, err := os.Stat(binexe); err != nil {
+ t.Fatal(err)
+ } else {
+ sizeexe = uint64(fi.Size())
+ }
+ if fi, err := os.Stat(binpie); err != nil {
+ t.Fatal(err)
+ } else {
+ sizepie = uint64(fi.Size())
+ }
+
+ elfexe, err := elf.Open(binexe)
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer elfexe.Close()
+
+ elfpie, err := elf.Open(binpie)
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer elfpie.Close()
+
+ // The difference in size between exe and PIE
+ // should be approximately the difference in
+ // size of the .text section plus the size of
+ // the PIE dynamic data sections plus the
+ // difference in size of the .got and .plt
+ // sections if they exist.
+ // We ignore unallocated sections.
+ // There may be gaps between non-writeable and
+ // writable PT_LOAD segments. We also skip those
+ // gaps (see issue #36023).
+
+ textsize := func(ef *elf.File, name string) uint64 {
+ for _, s := range ef.Sections {
+ if s.Name == ".text" {
+ return s.Size
+ }
+ }
+ t.Fatalf("%s: no .text section", name)
+ return 0
+ }
+ textexe := textsize(elfexe, binexe)
+ textpie := textsize(elfpie, binpie)
+
+ dynsize := func(ef *elf.File) uint64 {
+ var ret uint64
+ for _, s := range ef.Sections {
+ if s.Flags&elf.SHF_ALLOC == 0 {
+ continue
+ }
+ switch s.Type {
+ case elf.SHT_DYNSYM, elf.SHT_STRTAB, elf.SHT_REL, elf.SHT_RELA, elf.SHT_HASH, elf.SHT_GNU_HASH, elf.SHT_GNU_VERDEF, elf.SHT_GNU_VERNEED, elf.SHT_GNU_VERSYM:
+ ret += s.Size
+ }
+ if s.Flags&elf.SHF_WRITE != 0 && (strings.Contains(s.Name, ".got") || strings.Contains(s.Name, ".plt")) {
+ ret += s.Size
+ }
+ }
+ return ret
+ }
+
+ dynexe := dynsize(elfexe)
+ dynpie := dynsize(elfpie)
+
+ extrasize := func(ef *elf.File) uint64 {
+ var ret uint64
+ // skip unallocated sections
+ for _, s := range ef.Sections {
+ if s.Flags&elf.SHF_ALLOC == 0 {
+ ret += s.Size
+ }
+ }
+ // also skip gaps between PT_LOAD segments
+ var prev *elf.Prog
+ for _, seg := range ef.Progs {
+ if seg.Type != elf.PT_LOAD {
+ continue
+ }
+ if prev != nil {
+ ret += seg.Off - prev.Off - prev.Filesz
+ }
+ prev = seg
+ }
+ return ret
+ }
+
+ extraexe := extrasize(elfexe)
+ extrapie := extrasize(elfpie)
+
+ diffReal := (sizepie - extrapie) - (sizeexe - extraexe)
+ diffExpected := (textpie + dynpie) - (textexe + dynexe)
+
+ t.Logf("real size difference %#x, expected %#x", diffReal, diffExpected)
+
+ if diffReal > (diffExpected + diffExpected/10) {
+ t.Errorf("PIE unexpectedly large: got difference of %d (%d - %d), expected difference %d", diffReal, sizepie, sizeexe, diffExpected)
+ }
+ })
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-15 11:08:08 +0000