[dev.link] cmd/oldlink: update with recent change

Port CL 227864 to cmd/oldlink.

Change-Id: Ib05628e59a6616f422111b564a72c908c44062a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/228227
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/cmd/oldlink/internal/ld/elf.go b/src/cmd/oldlink/internal/ld/elf.go
index 610972118a54fa17a47a97b52000201e275259e3..28cab7575108ea9fbca5febd19152901d09f7897 100644 (file)
--- a/src/cmd/oldlink/internal/ld/elf.go
+++ b/src/cmd/oldlink/internal/ld/elf.go
@@ -849,6 +849,25 @@ func elfwritenetbsdsig(out *OutBuf) int {
        return int(sh.size)
 }
 
+// The race detector can't handle ASLR (address space layout randomization).
+// ASLR is on by default for NetBSD, so we turn the ASLR off eplicitly
+// using a magic elf Note when building race binaries.
+
+func elfnetbsdpax(sh *ElfShdr, startva uint64, resoff uint64) int {
+       n := int(Rnd(4, 4) + Rnd(4, 4))
+       return elfnote(sh, startva, resoff, n)
+}
+
+func elfwritenetbsdpax(out *OutBuf) int {
+       sh := elfwritenotehdr(out, ".note.netbsd.pax", 4 /* length of PaX\x00 */, 4 /* length of flags */, 0x03 /* PaX type */)
+       if sh == nil {
+               return 0
+       }
+       out.Write([]byte("PaX\x00"))
+       out.Write32(0x20) // 0x20 = Force disable ASLR
+       return int(sh.size)
+}
+
 // OpenBSD Signature
 const (
        ELF_NOTE_OPENBSD_NAMESZ  = 8
@@ -1451,6 +1470,9 @@ func (ctxt *Link) doelf() {
        }
        if ctxt.HeadType == objabi.Hnetbsd {
                Addstring(shstrtab, ".note.netbsd.ident")
+               if *flagRace {
+                       Addstring(shstrtab, ".note.netbsd.pax")
+               }
        }
        if ctxt.HeadType == objabi.Hopenbsd {
                Addstring(shstrtab, ".note.openbsd.ident")
@@ -1788,6 +1810,14 @@ func Asmbelf(ctxt *Link, symo int64) {
 
        var pph *ElfPhdr
        var pnote *ElfPhdr
+       if *flagRace && ctxt.HeadType == objabi.Hnetbsd {
+               sh := elfshname(".note.netbsd.pax")
+               resoff -= int64(elfnetbsdpax(sh, uint64(startva), uint64(resoff)))
+               pnote = newElfPhdr()
+               pnote.type_ = PT_NOTE
+               pnote.flags = PF_R
+               phsh(pnote, sh)
+       }
        if ctxt.LinkMode == LinkExternal {
                /* skip program headers */
                eh.phoff = 0
@@ -2265,6 +2295,9 @@ elfobj:
                        a += int64(elfwritegobuildid(ctxt.Out))
                }
        }
+       if *flagRace && ctxt.HeadType == objabi.Hnetbsd {
+               a += int64(elfwritenetbsdpax(ctxt.Out))
+       }
 
        if a > elfreserve {
                Errorf(nil, "ELFRESERVE too small: %d > %d with %d text sections", a, elfreserve, numtext)