From 61655555aa8c2cd5f5351ef7d0aea6dfce046135 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Tue, 12 Jul 2016 06:29:54 -0700
Subject: 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.
---
 configure.ac | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

(limited to 'configure.ac')

diff --git a/configure.ac b/configure.ac
index 123f0d26ee..33bcd62180 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1412,6 +1412,26 @@ elif test "$libc_cv_ssp" = "yes"; then
 fi
 AC_SUBST(stack_protector)
 
+AC_CACHE_CHECK([for -mtls-dialect=gnu2], libc_cv_mtls_dialect_gnu2,
+[dnl
+cat > conftest.c <<EOF
+__thread int i;
+void foo (void)
+{
+  i = 10;
+}
+EOF
+if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -S -fPIC -mtls-dialect=gnu2
+		   conftest.c 1>&AS_MESSAGE_LOG_FD])
+then
+  libc_cv_mtls_dialect_gnu2=yes
+else
+  libc_cv_mtls_dialect_gnu2=no
+fi
+rm -f conftest*])
+AC_SUBST(libc_cv_mtls_dialect_gnu2)
+LIBC_CONFIG_VAR([have-mtls-dialect-gnu2], [$libc_cv_mtls_dialect_gnu2])
+
 AC_CACHE_CHECK(whether cc puts quotes around section names,
 	       libc_cv_have_section_quotes,
 	       [cat > conftest.c <<EOF
-- 
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