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[PATCH] Don't use hidden visibility in libc.a with PIE on i386
- From: "H.J. Lu" <hongjiu dot lu at intel dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 22 Aug 2017 15:44:25 -0700
- Subject: [PATCH] Don't use hidden visibility in libc.a with PIE on i386
- Authentication-results: sourceware.org; auth=none
- Reply-to: "H.J. Lu" <hjl dot tools at gmail dot com>
On i386, when multi-arch is enabled, all external functions must be
called via PIC PLT in PIE, which requires setting up EBX register,
since they may be IFUNC functions.
OK for master?
H.J.
---
* config.h.in (NO_HIDDEN_EXTERN_FUNC_IN_PIE): New.
* include/libc-symbols.h (__hidden_proto_hiddenattr): Add check
for PIC and NO_HIDDEN_EXTERN_FUNC_IN_PIE.
* sysdeps/i386/configure.ac (NO_HIDDEN_EXTERN_FUNC_IN_PIE): New
AC_DEFINE if multi-arch is enabled.
* sysdeps/i386/configure: Regenerated.
---
config.h.in | 4 ++++
include/libc-symbols.h | 1 +
sysdeps/i386/configure | 7 ++++++-
sysdeps/i386/configure.ac | 6 ++++++
4 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/config.h.in b/config.h.in
index 26ed7865ef..d397eeae1a 100644
--- a/config.h.in
+++ b/config.h.in
@@ -86,6 +86,10 @@
#undef PI_STATIC_AND_HIDDEN
/* Define this to disable the 'hidden_proto' et al macros in
+ include/libc-symbols.h that avoid PLT slots in PIE. */
+#undef NO_HIDDEN_EXTERN_FUNC_IN_PIE
+
+/* Define this to disable the 'hidden_proto' et al macros in
include/libc-symbols.h that avoid PLT slots in the shared objects. */
#undef NO_HIDDEN
diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index fe3571af52..4668902d5f 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -514,6 +514,7 @@ for linking")
#else
# ifndef __ASSEMBLER__
# if !defined SHARED && IS_IN (libc) && !defined LIBC_NONSHARED \
+ && (!defined PIC || !defined NO_HIDDEN_EXTERN_FUNC_IN_PIE) \
&& !defined NO_HIDDEN
# define __hidden_proto_hiddenattr(attrs...) \
__attribute__ ((visibility ("hidden"), ##attrs))
diff --git a/sysdeps/i386/configure b/sysdeps/i386/configure
index 4d6685f7c2..4cf968d8bc 100644
--- a/sysdeps/i386/configure
+++ b/sysdeps/i386/configure
@@ -26,7 +26,7 @@ libc_compiler_builtin_inlined=no
cat > conftest.c <<EOF
int _start (void) { int a, b, c; __sync_val_compare_and_swap (&a, b, c); return 0; }
EOF
-if ! { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS
+if ! { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp
-O0 -nostdlib -nostartfiles
-S conftest.c -o - | fgrep "__sync_val_compare_and_swap"
1>&5'
@@ -79,3 +79,8 @@ fi
$as_echo "#define PI_STATIC_AND_HIDDEN 1" >>confdefs.h
+
+if test x"$multi_arch" != xno; then
+ $as_echo "#define NO_HIDDEN_EXTERN_FUNC_IN_PIE 1" >>confdefs.h
+
+fi
diff --git a/sysdeps/i386/configure.ac b/sysdeps/i386/configure.ac
index f7766ad2b8..b598b120bc 100644
--- a/sysdeps/i386/configure.ac
+++ b/sysdeps/i386/configure.ac
@@ -48,3 +48,9 @@ fi
dnl It is always possible to access static and hidden symbols in an
dnl position independent way.
AC_DEFINE(PI_STATIC_AND_HIDDEN)
+
+dnl When multi-arch is enabled, all external functions must be called
+dnl via PIC PLT in PIE, which requires setting up EBX register.
+if test x"$multi_arch" != xno; then
+ AC_DEFINE(NO_HIDDEN_EXTERN_FUNC_IN_PIE)
+fi
--
2.13.5