r338682 | emaste | 2018-09-14 17:15:16 +0200 (Fri, 14 Sep 2018) | 16 lines

lld: add -z interpose support

-z interpose sets the DF_1_INTERPOSE flag, marking the object as an
interposer.

Committed upstream as LLVM r342239.

PR:		230604
Reported by:	jbeich
Reviewed by:	markj
Approved by:	re (kib)
MFC after:	1 week
Relnotes:	Yes
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D17172

Index: tools/lld/ELF/Config.h
===================================================================
--- tools/lld/ELF/Config.h	(revision 338681)
+++ tools/lld/ELF/Config.h	(revision 338682)
@@ -183,6 +183,7 @@ struct Configuration {
   bool ZHazardplt;
   bool ZIfuncnoplt;
   bool ZInitfirst;
+  bool ZInterpose;
   bool ZKeepTextSectionPrefix;
   bool ZNodelete;
   bool ZNodlopen;
Index: tools/lld/ELF/Driver.cpp
===================================================================
--- tools/lld/ELF/Driver.cpp	(revision 338681)
+++ tools/lld/ELF/Driver.cpp	(revision 338682)
@@ -339,7 +339,7 @@ static bool getZFlag(opt::InputArgList &Args, StringRe
 static bool isKnown(StringRef S) {
   return S == "combreloc" || S == "copyreloc" || S == "defs" ||
          S == "execstack" || S == "hazardplt" || S == "ifunc-noplt" ||
-         S == "initfirst" ||
+         S == "initfirst" || S == "interpose" ||
          S == "keep-text-section-prefix" || S == "lazy" || S == "muldefs" ||
          S == "nocombreloc" || S == "nocopyreloc" || S == "nodelete" ||
          S == "nodlopen" || S == "noexecstack" ||
@@ -846,6 +846,7 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args
   Config->ZHazardplt = hasZOption(Args, "hazardplt");
   Config->ZIfuncnoplt = hasZOption(Args, "ifunc-noplt");
   Config->ZInitfirst = hasZOption(Args, "initfirst");
+  Config->ZInterpose = hasZOption(Args, "interpose");
   Config->ZKeepTextSectionPrefix = getZFlag(
       Args, "keep-text-section-prefix", "nokeep-text-section-prefix", false);
   Config->ZNodelete = hasZOption(Args, "nodelete");
Index: tools/lld/ELF/SyntheticSections.cpp
===================================================================
--- tools/lld/ELF/SyntheticSections.cpp	(revision 338681)
+++ tools/lld/ELF/SyntheticSections.cpp	(revision 338682)
@@ -1266,6 +1266,8 @@ template <class ELFT> void DynamicSection<ELFT>::final
     DtFlags |= DF_SYMBOLIC;
   if (Config->ZInitfirst)
     DtFlags1 |= DF_1_INITFIRST;
+  if (Config->ZInterpose)
+    DtFlags1 |= DF_1_INTERPOSE;
   if (Config->ZNodelete)
     DtFlags1 |= DF_1_NODELETE;
   if (Config->ZNodlopen)