x86-64: Properly align stack in _dl_tlsdesc_dynamic [BZ #20309]

Since _dl_tlsdesc_dynamic is called via PLT, we need to add 8 bytes for
push in the PLT entry to align the stack.

	[BZ #20309]
	* configure.ac (have-mtls-dialect-gnu2): Set to yes if
	-mtls-dialect=gnu2 works.
	* configure: Regenerated.
	* elf/Makefile [have-mtls-dialect-gnu2 = yes]
	(tests): Add tst-gnu2-tls1.
	(modules-names): Add tst-gnu2-tls1mod.
	($(objpfx)tst-gnu2-tls1): New.
	(tst-gnu2-tls1mod.so-no-z-defs): Likewise.
	(CFLAGS-tst-gnu2-tls1mod.c): Likewise.
	* elf/tst-gnu2-tls1.c: New file.
	* elf/tst-gnu2-tls1mod.c: Likewise.
	* sysdeps/x86_64/dl-tlsdesc.S (_dl_tlsdesc_dynamic): Add 8
	bytes for push in the PLT entry to align the stack.

1 files changed, 33 insertions, 0 deletions

diff --git a/configure b/configure
index 19a4829466..17625e1041 100755
--- a/configure
+++ b/configure
@@ -619,6 +619,7 @@ LIBGD
 libc_cv_cc_loop_to_function
 libc_cv_cc_submachine
 libc_cv_cc_nofma
+libc_cv_mtls_dialect_gnu2
 stack_protector
 fno_unit_at_a_time
 libc_cv_output_format
@@ -5824,6 +5825,38 @@ elif test "$libc_cv_ssp" = "yes"; then
 fi
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for -mtls-dialect=gnu2" >&5
+$as_echo_n "checking for -mtls-dialect=gnu2... " >&6; }
+if ${libc_cv_mtls_dialect_gnu2+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat > conftest.c <<EOF
+__thread int i;
+void foo (void)
+{
+  i = 10;
+}
+EOF
+if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -S -fPIC -mtls-dialect=gnu2
+		   conftest.c 1>&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then
+  libc_cv_mtls_dialect_gnu2=yes
+else
+  libc_cv_mtls_dialect_gnu2=no
+fi
+rm -f conftest*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_mtls_dialect_gnu2" >&5
+$as_echo "$libc_cv_mtls_dialect_gnu2" >&6; }
+
+config_vars="$config_vars
+have-mtls-dialect-gnu2 = $libc_cv_mtls_dialect_gnu2"
+
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether cc puts quotes around section names" >&5
 $as_echo_n "checking whether cc puts quotes around section names... " >&6; }
 if ${libc_cv_have_section_quotes+:} false; then :