Support compilers defaulting to PIE

To support building glibc with GCC 6 configured with --enable-default-pie,
which generates PIE by default, we need to build programs as PIE.  But
elf/tst-dlopen-aout must not be built as PIE since it tests dlopen on
ET_EXEC file and PIE is ET_DYN.

	[BZ #17841]
	* Makeconfig (no-pie-ldflag): New.
	(+link): Set to $(+link-pie) if default to PIE.
	(+link-tests): Set to $(+link-pie-tests) if default to PIE.
	* config.make.in (build-pie-default): New.
	* configure.ac (libc_cv_pie_default): New.  Set to yes if -fPIE
	is default.  AC_SUBST.
	* configure: Regenerated.
	* elf/Makefile (LDFLAGS-tst-dlopen-aout): New.

5 files changed, 42 insertions, 0 deletions

diff --git a/Makeconfig b/Makeconfig
index d32a0fdc65..831604a050 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -442,6 +442,11 @@ endif
 # Commands for linking programs with the C library.
 ifndef +link
 ifeq (yes,$(build-shared))
+ifeq (yes,$(build-pie-default))
+no-pie-ldflag = -no-pie
++link = $(+link-pie)
++link-tests = $(+link-pie-tests)
+else
 +link-before-libc = $(CC) -nostdlib -nostartfiles -o $@ \
 	      $(sysdep-LDFLAGS) $(LDFLAGS) $(LDFLAGS-$(@F)) \
 	      $(combreloc-LDFLAGS) $(relro-LDFLAGS) $(hashstyle-LDFLAGS) \
@@ -462,6 +467,7 @@ $(+link-before-libc) $(rtld-tests-LDFLAGS) $(link-libc-tests) \
 		     $(+link-after-libc)
 $(call after-link,$@)
 endef
+endif
 else
 +link = $(+link-static)
 +link-tests = $(+link-static-tests)
diff --git a/config.make.in b/config.make.in
index 5a18daed24..a9f5696077 100644
--- a/config.make.in
+++ b/config.make.in
@@ -82,6 +82,7 @@ nss-crypt = @libc_cv_nss_crypt@
 # Configuration options.
 build-shared = @shared@
 build-pic-default= @libc_cv_pic_default@
+build-pie-default= @libc_cv_pie_default@
 build-profile = @profile@
 build-static-nss = @static_nss@
 add-ons = @add_ons@
diff --git a/configure b/configure
index 1e4138b524..45cc7cba2b 100755
--- a/configure
+++ b/configure
@@ -596,6 +596,7 @@ mach_interface_list
 DEFINES
 static_nss
 profile
+libc_cv_pie_default
 libc_cv_pic_default
 shared
 static
@@ -7317,6 +7318,26 @@ fi
 $as_echo "$libc_cv_pic_default" >&6; }
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether -fPIE is default" >&5
+$as_echo_n "checking whether -fPIE is default... " >&6; }
+if ${libc_cv_pie_default+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  libc_cv_pie_default=yes
+cat > conftest.c <<EOF
+#if defined __PIE__ || defined __pie__ || defined PIE || defined pie
+# error PIE is default.
+#endif
+EOF
+if eval "${CC-cc} -S conftest.c 2>&5 1>&5"; then
+  libc_cv_pie_default=no
+fi
+rm -f conftest.*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_pie_default" >&5
+$as_echo "$libc_cv_pie_default" >&6; }
+
+
 
 
 
diff --git a/configure.ac b/configure.ac
index ff66b875e3..7e9383a7f0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2075,6 +2075,19 @@ fi
 rm -f conftest.*])
 AC_SUBST(libc_cv_pic_default)
 
+AC_CACHE_CHECK([whether -fPIE is default], libc_cv_pie_default,
+[libc_cv_pie_default=yes
+cat > conftest.c <<EOF
+#if defined __PIE__ || defined __pie__ || defined PIE || defined pie
+# error PIE is default.
+#endif
+EOF
+if eval "${CC-cc} -S conftest.c 2>&AS_MESSAGE_LOG_FD 1>&AS_MESSAGE_LOG_FD"; then
+  libc_cv_pie_default=no
+fi
+rm -f conftest.*])
+AC_SUBST(libc_cv_pie_default)
+
 AC_SUBST(profile)
 AC_SUBST(static_nss)
 
diff --git a/elf/Makefile b/elf/Makefile
index dedf3c7f50..d4421e9209 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -150,6 +150,7 @@ tests += loadtest restest1 preloadtest loadfail multiload origtest resolvfail \
 #	 reldep9
 ifeq ($(build-hardcoded-path-in-tests),yes)
 tests += tst-dlopen-aout
+LDFLAGS-tst-dlopen-aout = $(no-pie-ldflag)
 endif
 test-srcs = tst-pathopt
 selinux-enabled := $(shell cat /selinux/enforce 2> /dev/null)