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cmd/link: merge note sections into one segment 

The ld from binutils merges note sections into one PT_NOTE
segment.
We should do that for consistency with binutils.

Change-Id: I45703525c720972d49c36c4f10ac47d1628b5698
Reviewed-on: https://go-review.googlesource.com/c/go/+/265957
Trust: Meng Zhuo <mzh@golangcn.org>
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
Run-TryBot: Meng Zhuo <mzh@golangcn.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Meng Zhuo 2021-03-30 19:58:35 +08:00
parent 78af02e8b5
commit 1ea4d3b911
2 changed files with 71 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
src/cmd/link/elf_test.go
View File

@ -201,6 +201,61 @@ func TestMinusRSymsWithSameName(t *testing.T) {
}
}
func TestMergeNoteSections(t *testing.T) {
testenv.MustHaveGoBuild(t)
expected := 1
switch runtime.GOOS {
case "linux", "freebsd", "dragonfly":
case "openbsd", "netbsd":
// These OSes require independent segment
expected = 2
default:
t.Skip("We should only test on elf output.")
}
t.Parallel()
goFile := filepath.Join(t.TempDir(), "notes.go")
if err := ioutil.WriteFile(goFile, []byte(goSource), 0444); err != nil {
t.Fatal(err)
}
outFile := filepath.Join(t.TempDir(), "notes.exe")
goTool := testenv.GoToolPath(t)
// sha1sum of "gopher"
id := "0xf4e8cd51ce8bae2996dc3b74639cdeaa1f7fee5f"
cmd := exec.Command(goTool, "build", "-o", outFile, "-ldflags",
"-B "+id, goFile)
cmd.Dir = t.TempDir()
if out, err := cmd.CombinedOutput(); err != nil {
t.Logf("%s", out)
t.Fatal(err)
}
ef, err := elf.Open(outFile)
if err != nil {
t.Fatalf("open elf file failed:%v", err)
}
defer ef.Close()
sec := ef.Section(".note.gnu.build-id")
if sec == nil {
t.Fatalf("can't find gnu build id")
}
sec = ef.Section(".note.go.buildid")
if sec == nil {
t.Fatalf("can't find go build id")
}
cnt := 0
for _, ph := range ef.Progs {
if ph.Type == elf.PT_NOTE {
cnt += 1
}
}
if cnt != expected {
t.Fatalf("want %d PT_NOTE segment, got %d", expected, cnt)
}
}
const pieSourceTemplate = `
package main

39
src/cmd/link/internal/ld/elf.go
View File

@ -1682,13 +1682,18 @@ func asmbElf(ctxt *Link) {
var pph *ElfPhdr
var pnote *ElfPhdr
getpnote := func() *ElfPhdr {
if pnote == nil {
pnote = newElfPhdr()
pnote.Type = elf.PT_NOTE
pnote.Flags = elf.PF_R
}
return pnote
}
if *flagRace && ctxt.IsNetbsd() {
sh := elfshname(".note.netbsd.pax")
resoff -= int64(elfnetbsdpax(sh, uint64(startva), uint64(resoff)))
pnote = newElfPhdr()
pnote.Type = elf.PT_NOTE
pnote.Flags = elf.PF_R
phsh(pnote, sh)
phsh(getpnote(), sh)
}
if ctxt.LinkMode == LinkExternal {
/* skip program headers */
@ -1787,7 +1792,6 @@ func asmbElf(ctxt *Link) {
phsh(ph, sh)
}
pnote = nil
if ctxt.HeadType == objabi.Hnetbsd || ctxt.HeadType == objabi.Hopenbsd {
var sh *ElfShdr
switch ctxt.HeadType {
@ -1799,34 +1803,23 @@ func asmbElf(ctxt *Link) {
sh = elfshname(".note.openbsd.ident")
resoff -= int64(elfopenbsdsig(sh, uint64(startva), uint64(resoff)))
}
pnote = newElfPhdr()
pnote.Type = elf.PT_NOTE
pnote.Flags = elf.PF_R
phsh(pnote, sh)
// netbsd and openbsd require ident in an independent segment.
pnotei := newElfPhdr()
pnotei.Type = elf.PT_NOTE
pnotei.Flags = elf.PF_R
phsh(pnotei, sh)
}
if len(buildinfo) > 0 {
sh := elfshname(".note.gnu.build-id")
resoff -= int64(elfbuildinfo(sh, uint64(startva), uint64(resoff)))
if pnote == nil {
pnote = newElfPhdr()
pnote.Type = elf.PT_NOTE
pnote.Flags = elf.PF_R
}
phsh(pnote, sh)
phsh(getpnote(), sh)
}
if *flagBuildid != "" {
sh := elfshname(".note.go.buildid")
resoff -= int64(elfgobuildid(sh, uint64(startva), uint64(resoff)))
pnote := newElfPhdr()
pnote.Type = elf.PT_NOTE
pnote.Flags = elf.PF_R
phsh(pnote, sh)
phsh(getpnote(), sh)
}
// Additions to the reserved area must be above this line.