cmd/link: test that moduledata is in its own section

This is a test for CL 720660.

For #76038

Change-Id: I2f630b738ddb5a9c48e3c5d4374c1e995910541a
Reviewed-on: https://go-review.googlesource.com/c/go/+/721480
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Chase <drchase@google.com>

diff --git a/src/cmd/link/link_test.go b/src/cmd/link/link_test.go
index 77bbc3c1f8a08975d55d51328140d1b12c1736ed..0c4cde0399fbd5457b1410735bee06163b1ee04a 100644 (file)
--- a/src/cmd/link/link_test.go
+++ b/src/cmd/link/link_test.go
@@ -2114,3 +2114,100 @@ func TestFuncdataPlacement(t *testing.T) {
                t.Errorf("findfunctab address %#x not between %#x and %#x", moddata.findfunctab, pclntabAddr, pclntabEnd)
        }
 }
+
+// Test that moduledata winds up in its own .go.module section.
+func TestModuledataPlacement(t *testing.T) {
+       testenv.MustHaveGoBuild(t)
+       t.Parallel()
+
+       tmpdir := t.TempDir()
+       src := filepath.Join(tmpdir, "x.go")
+       if err := os.WriteFile(src, []byte(trivialSrc), 0o444); err != nil {
+               t.Fatal(err)
+       }
+
+       exe := filepath.Join(tmpdir, "x.exe")
+       cmd := goCmd(t, "build", "-o", exe, src)
+       if out, err := cmd.CombinedOutput(); err != nil {
+               t.Fatalf("build failed; %v, output:\n%s", err, out)
+       }
+
+       ef, _ := elf.Open(exe)
+       mf, _ := macho.Open(exe)
+       pf, _ := pe.Open(exe)
+       xf, _ := xcoff.Open(exe)
+       // TODO: plan9
+       if ef == nil && mf == nil && pf == nil && xf == nil {
+               t.Skip("unrecognized executable file format")
+       }
+
+       const moddataSymName = "runtime.firstmoduledata"
+       switch {
+       case ef != nil:
+               defer ef.Close()
+
+               syms, err := ef.Symbols()
+               if err != nil {
+                       t.Fatal(err)
+               }
+               for _, sym := range syms {
+                       if sym.Name == moddataSymName {
+                               sec := ef.Sections[sym.Section]
+                               if sec.Name != ".go.module" {
+                                       t.Errorf("moduledata in section %s, not .go.module", sec.Name)
+                               }
+                               if sym.Value != sec.Addr {
+                                       t.Errorf("moduledata address %#x != section start address %#x", sym.Value, sec.Addr)
+                               }
+                               break
+                       }
+               }
+
+       case mf != nil:
+               defer mf.Close()
+
+               for _, sym := range mf.Symtab.Syms {
+                       if sym.Name == moddataSymName {
+                               if sym.Sect == 0 {
+                                       t.Error("moduledata not in a section")
+                               } else {
+                                       sec := mf.Sections[sym.Sect-1]
+                                       if sec.Name != "__go_module" {
+                                               t.Errorf("moduledata in section %s, not __go.module", sec.Name)
+                                       }
+                                       if sym.Value != sec.Addr {
+                                               t.Errorf("moduledata address %#x != section start address %#x", sym.Value, sec.Addr)
+                                       }
+                               }
+                               break
+                       }
+               }
+
+       case pf != nil:
+               defer pf.Close()
+
+               // On Windows all the Go specific sections seem to
+               // get stuffed into a few Windows sections,
+               // so there is nothing to test here.
+
+       case xf != nil:
+               defer xf.Close()
+
+               for _, sym := range xf.Symbols {
+                       if sym.Name == moddataSymName {
+                               if sym.SectionNumber == 0 {
+                                       t.Errorf("moduledata not in a section")
+                               } else {
+                                       sec := xf.Sections[sym.SectionNumber-1]
+                                       if sec.Name != ".go.module" {
+                                               t.Errorf("moduledata in section %s, not .go.module", sec.Name)
+                                       }
+                                       if sym.Value != sec.VirtualAddress {
+                                               t.Errorf("moduledata address %#x != section start address %#x", sym.Value, sec.VirtualAddress)
+                                       }
+                               }
+                               break
+                       }
+               }
+       }
+}