ld: Add a linker configure option --enable-relro

Add a configure option --enable-relro to decide whether -z relro should
be enabled in ELF linker by default.  Default to yes for all Linux
targets, except FRV, HPPA, IA64 and MIPS, since many relro tests fail
on these targets.

	PR ld/20283
	* NEWS: Mention --enable-relro.
	* configure.ac: Add --enable-relro.
	(DEFAULT_LD_Z_RELRO): New.  Set by --enable-relro.
	* configure.tgt (ac_default_ld_z_relro): Default it to 1 for
	some Linux targets.
	* config.in: Regenerated.
	* configure: Likewise.
	* emultempl/elf32.em (gld${EMULATION_NAME}_before_parse): Set
	link_info.relro to DEFAULT_LD_Z_RELRO.
	* testsuite/config/default.exp (ld_elf_shared_opt): New.
	* testsuite/lib/ld-lib.exp (run_dump_test): Pass
	$ld_elf_shared_opt to ld for ELF targets with shared object
	support.
	(run_ld_link_tests): Likewise.

9 files changed, 112 insertions, 4 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 7a2d781..8c85993 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,21 @@
+2016-06-22  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR ld/20283
+	* NEWS: Mention --enable-relro.
+	* configure.ac: Add --enable-relro.
+	(DEFAULT_LD_Z_RELRO): New.  Set by --enable-relro.
+	* configure.tgt (ac_default_ld_z_relro): Default it to 1 for
+	some Linux targets.
+	* config.in: Regenerated.
+	* configure: Likewise.
+	* emultempl/elf32.em (gld${EMULATION_NAME}_before_parse): Set
+	link_info.relro to DEFAULT_LD_Z_RELRO.
+	* testsuite/config/default.exp (ld_elf_shared_opt): New.
+	* testsuite/lib/ld-lib.exp (run_dump_test): Pass
+	$ld_elf_shared_opt to ld for ELF targets with shared object
+	support.
+	(run_ld_link_tests): Likewise.
+
 2016-06-21  Maciej W. Rozycki  <macro@imgtec.com>
 
 	* testsuite/ld-mips-elf/mode-change-error-1a.s: Trigger an error
diff --git a/ld/NEWS b/ld/NEWS
index 228fddf..b373f7c 100644
--- a/ld/NEWS
+++ b/ld/NEWS
@@ -1,5 +1,9 @@
 -*- text -*-
 
+* Add a configure option --enable-relro to decide whether -z relro should
+  be enabled in ELF linker by default.  Default to yes for all Linux
+  targets except FRV, HPPA, IA64 and MIPS.
+
 * Support for -z noreloc-overflow in the x86-64 ELF linker to disable
   relocation overflow check.
 
diff --git a/ld/config.in b/ld/config.in
index 276fb77..2c6d698 100644
--- a/ld/config.in
+++ b/ld/config.in
@@ -10,6 +10,9 @@
 /* Define if you want compressed debug sections by default. */
 #undef DEFAULT_FLAG_COMPRESS_DEBUG
 
+/* Define to 1 if you want to enable -z relro in ELF linker by default. */
+#undef DEFAULT_LD_Z_RELRO
+
 /* Define to 1 if translation of program messages to the user's native
    language is requested. */
 #undef ENABLE_NLS
diff --git a/ld/configure b/ld/configure
index da93e07..a469ad4 100755
--- a/ld/configure
+++ b/ld/configure
@@ -791,6 +791,7 @@ with_sysroot
 enable_gold
 enable_got
 enable_compressed_debug_sections
+enable_relro
 enable_werror
 enable_build_warnings
 enable_nls
@@ -1449,6 +1450,7 @@ Optional Features:
                           multigot)
   --enable-compressed-debug-sections={all,ld,none}
                           compress debug sections by default]
+  --enable-relro          enable -z relro in ELF linker by default
   --enable-werror         treat compile warnings as errors
   --enable-build-warnings enable build-time compiler warnings
   --disable-nls           do not use Native Language Support
@@ -11721,7 +11723,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11724 "configure"
+#line 11726 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11827,7 +11829,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11830 "configure"
+#line 11832 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -15541,6 +15543,17 @@ if test "${enable_compressed_debug_sections+set}" = set; then :
 esac
 fi
 
+# Decide if -z relro should be enabled in ELF linker by default.
+ac_default_ld_z_relro=unset
+# Provide a configure time option to override our default.
+# Check whether --enable-relro was given.
+if test "${enable_relro+set}" = set; then :
+  enableval=$enable_relro; case "${enableval}" in
+  yes)  ac_default_ld_z_relro=1 ;;
+  no)  ac_default_ld_z_relro=0 ;;
+esac
+fi
+
 
 # Set the 'development' global.
 . $srcdir/../bfd/development.sh
@@ -17147,6 +17160,15 @@ $as_echo "#define DEFAULT_FLAG_COMPRESS_DEBUG 1" >>confdefs.h
 
 fi
 
+if test "${ac_default_ld_z_relro}" = unset; then
+  ac_default_ld_z_relro=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define DEFAULT_LD_Z_RELRO $ac_default_ld_z_relro
+_ACEOF
+
+
 
 
 
diff --git a/ld/configure.ac b/ld/configure.ac
index 6542506..d17281f 100644
--- a/ld/configure.ac
+++ b/ld/configure.ac
@@ -155,6 +155,17 @@ AC_ARG_ENABLE(compressed_debug_sections,
   ,no, | ,none,)  ac_default_compressed_debug_sections=no ;;
 esac])dnl
 
+# Decide if -z relro should be enabled in ELF linker by default.
+ac_default_ld_z_relro=unset
+# Provide a configure time option to override our default.
+AC_ARG_ENABLE(relro,
+	      AS_HELP_STRING([--enable-relro],
+	      [enable -z relro in ELF linker by default]),
+[case "${enableval}" in
+  yes)  ac_default_ld_z_relro=1 ;;
+  no)  ac_default_ld_z_relro=0 ;;
+esac])dnl
+
 AM_BINUTILS_WARNINGS
 
 AM_LC_MESSAGES
@@ -376,6 +387,13 @@ if test x$ac_default_compressed_debug_sections = xyes ; then
   AC_DEFINE(DEFAULT_FLAG_COMPRESS_DEBUG, 1, [Define if you want compressed debug sections by default.])
 fi
 
+if test "${ac_default_ld_z_relro}" = unset; then
+  ac_default_ld_z_relro=0
+fi
+AC_DEFINE_UNQUOTED(DEFAULT_LD_Z_RELRO,
+  $ac_default_ld_z_relro,
+  [Define to 1 if you want to enable -z relro in ELF linker by default.])
+
 AC_SUBST(elf_list_options)
 AC_SUBST(elf_shlib_list_options)
 AC_SUBST(elf_plt_unwind_list_options)
diff --git a/ld/configure.tgt b/ld/configure.tgt
index 6251943..a3db909 100644
--- a/ld/configure.tgt
+++ b/ld/configure.tgt
@@ -882,3 +882,28 @@ alpha*-*-*)
   ;;
 
 esac
+
+case "${target}" in
+frv-*-* | hppa*-*-* | ia64-*-* | mips*-*-*)
+  # Don't enable -z relro by default since many relro tests fail on these
+  # targets:
+  # FAIL: strip -z relro (relro1)
+  # FAIL: strip -z relro -shared (relro1)
+  # FAIL: objcopy -z relro (relro1)
+  # FAIL: objcopy -z relro -shared (relro1)
+  # FAIL: objcopy -z relro (tdata1)
+  # FAIL: objcopy -shared -z relro (tdata1)
+  # FAIL: objcopy -z relro (tdata2)
+  # FAIL: objcopy -shared -z relro (tdata2)
+  # FAIL: objcopy -z relro (tdata3)
+  # FAIL: objcopy -shared -z relro (tdata3)
+  # FAIL: objcopy -shared -z relro (tbss1)
+  # FAIL: objcopy -shared -z relro (tbss2)
+  # FAIL: objcopy -shared -z relro (tbss3)
+  ;;
+*-*-linux*)
+  if test ${ac_default_ld_z_relro} = unset; then
+    ac_default_ld_z_relro=1
+  fi
+  ;;
+esac
diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index c2ad202..47fa549 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -105,6 +105,7 @@ gld${EMULATION_NAME}_before_parse (void)
   config.separate_code = `if test "x${SEPARATE_CODE}" = xyes ; then echo TRUE ; else echo FALSE ; fi`;
   `if test -n "$CALL_NOP_BYTE" ; then echo link_info.call_nop_byte = $CALL_NOP_BYTE; fi`;
   link_info.check_relocs_after_open_input = `if test "x${CHECK_RELOCS_AFTER_OPEN_INPUT}" = xyes ; then echo TRUE ; else echo FALSE ; fi`;
+  link_info.relro = DEFAULT_LD_Z_RELRO;
 }
 
 EOF
diff --git a/ld/testsuite/config/default.exp b/ld/testsuite/config/default.exp
index 8ccad11..208c0d3 100644
--- a/ld/testsuite/config/default.exp
+++ b/ld/testsuite/config/default.exp
@@ -76,6 +76,9 @@ if {[file exists tmpdir/libpath.exp]} {
     }
 }
 
+# Many ELF testcases expect that "-z relro" is off.
+set ld_elf_shared_opt "-z norelro"
+
 # The "make check" target in the Makefile passes in
 # "CC=$(CC_FOR_TARGET)".  But, if the user invokes runtest directly
 # (as when testing an installed linker), these flags may not be set.  
diff --git a/ld/testsuite/lib/ld-lib.exp b/ld/testsuite/lib/ld-lib.exp
index 29af846..62f9768 100644
--- a/ld/testsuite/lib/ld-lib.exp
+++ b/ld/testsuite/lib/ld-lib.exp
@@ -589,6 +589,13 @@ proc run_dump_test { name {extra_options {}} } {
     global OBJDUMPFLAGS NMFLAGS ASFLAGS OBJCOPYFLAGS READELFFLAGS LDFLAGS
     global host_triplet runtests
     global env verbose
+    global ld_elf_shared_opt
+
+    if { [is_elf_format] && [check_shared_lib_support] } {
+	set ld_extra_opt "$ld_elf_shared_opt"
+    } else {
+	set ld_extra_opt ""
+    }
 
     if [string match "*/*" $name] {
 	set file $name
@@ -912,7 +919,7 @@ proc run_dump_test { name {extra_options {}} } {
 
 	# Add -L$srcdir/$subdir so that the linker command can use
 	# linker scripts in the source directory.
-	set cmd "$LD $LDFLAGS -L$srcdir/$subdir \
+	set cmd "$LD $ld_extra_opt $LDFLAGS -L$srcdir/$subdir \
 		   $opts(ld) -o $objfile $objfiles $opts(ld_after_inputfiles)"
 
         # If needed then check for, or add a -Map option.
@@ -1166,6 +1173,13 @@ proc run_ld_link_tests { ldtests } {
     global CFLAGS
     global runtests
     global exec_output
+    global ld_elf_shared_opt
+
+    if { [is_elf_format] && [check_shared_lib_support] } {
+	set ld_extra_opt "$ld_elf_shared_opt"
+    } else {
+	set ld_extra_opt ""
+    }
 
     foreach testitem $ldtests {
 	set testname [lindex $testitem 0]
@@ -1228,7 +1242,7 @@ proc run_ld_link_tests { ldtests } {
 	    if { ![ar_simple_create $ar $ld_options $binfile "$objfiles $ld_after"] } {
 		set failed 1
 	    }
-	} elseif { ![ld_simple_link $ld $binfile "-L$srcdir/$subdir $ld_options $objfiles $ld_after"] } {
+	} elseif { ![ld_simple_link $ld $binfile "$ld_extra_opt -L$srcdir/$subdir $ld_options $objfiles $ld_after"] } {
 	    set maybe_failed 1
 	    set ld_output "$exec_output"
 	}