From b75d311fbb53cb2f9c857349a6cd1877b411ff60 Mon Sep 17 00:00:00 2001 From: Francis Deslauriers Date: Tue, 10 Jul 2018 14:36:44 -0400 Subject: [PATCH] Fix: Tests: use -no-pie linker option only when available MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Issue ===== To keep the userspace callstack tests simple, we want to prevent the testapp to be linked as a Position Independent Execution (PIE) binary as it is simpler to resolve the addresses of functions. Some distributions now ship GCC built with the --enable-default-pie option which turns on PIE by default. To prevent that, we use the -no-pie linker flag when building the gen-syscall-events-callstack testapp. The issue is that this flag is not available on older version of GCC thus triggering an error when building the project. gcc: error: unrecognized command line option ‘-no-pie’ Solution ======== Test for the availability of the -no-pie option at the configure time and enable it only when found. If the option is unavailable we assume that the -pie option is not enabled by default thus removing the need to prevent its usage with -no-pie in the first place. Known drawbacks =============== None Signed-off-by: Francis Deslauriers Signed-off-by: Jérémie Galarneau --- configure.ac | 4 + m4/ax_check_link_flag.m4 | 74 +++++++++++++++++++ .../gen-syscall-events-callstack/Makefile.am | 12 ++- 3 files changed, 89 insertions(+), 1 deletion(-) create mode 100644 m4/ax_check_link_flag.m4 diff --git a/configure.ac b/configure.ac index acae225ad..f5501cebd 100644 --- a/configure.ac +++ b/configure.ac @@ -112,6 +112,10 @@ AS_IF([test "x$ax_cv___attribute__" = "xyes"], AX_PTHREAD(,[AC_MSG_ERROR([Could not configure pthreads support])]) +# Check if linker has the -no-pie option. +AX_CHECK_LINK_FLAG([-no-pie], [linker_have_no_pie_option=yes]) +AM_CONDITIONAL([LINKER_HAVE_NO_PIE_OPTION], [test "x$linker_have_no_pie_option" = "xyes"]) + AX_LIB_SOCKET_NSL LT_NO_UNDEFINED="" diff --git a/m4/ax_check_link_flag.m4 b/m4/ax_check_link_flag.m4 new file mode 100644 index 000000000..819409a20 --- /dev/null +++ b/m4/ax_check_link_flag.m4 @@ -0,0 +1,74 @@ +# =========================================================================== +# https://www.gnu.org/software/autoconf-archive/ax_check_link_flag.html +# =========================================================================== +# +# SYNOPSIS +# +# AX_CHECK_LINK_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT]) +# +# DESCRIPTION +# +# Check whether the given FLAG works with the linker or gives an error. +# (Warnings, however, are ignored) +# +# ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on +# success/failure. +# +# If EXTRA-FLAGS is defined, it is added to the linker's default flags +# when the check is done. The check is thus made with the flags: "LDFLAGS +# EXTRA-FLAGS FLAG". This can for example be used to force the linker to +# issue an error when a bad flag is given. +# +# INPUT gives an alternative input source to AC_LINK_IFELSE. +# +# NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this +# macro in sync with AX_CHECK_{PREPROC,COMPILE}_FLAG. +# +# LICENSE +# +# Copyright (c) 2008 Guido U. Draheim +# Copyright (c) 2011 Maarten Bosmans +# +# This program is free software: you can redistribute it and/or modify it +# under the terms of the GNU General Public License as published by the +# Free Software Foundation, either version 3 of the License, or (at your +# option) any later version. +# +# This program is distributed in the hope that it will be useful, but +# WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General +# Public License for more details. +# +# You should have received a copy of the GNU General Public License along +# with this program. If not, see . +# +# As a special exception, the respective Autoconf Macro's copyright owner +# gives unlimited permission to copy, distribute and modify the configure +# scripts that are the output of Autoconf when processing the Macro. You +# need not follow the terms of the GNU General Public License when using +# or distributing such scripts, even though portions of the text of the +# Macro appear in them. The GNU General Public License (GPL) does govern +# all other use of the material that constitutes the Autoconf Macro. +# +# This special exception to the GPL applies to versions of the Autoconf +# Macro released by the Autoconf Archive. When you make and distribute a +# modified version of the Autoconf Macro, you may extend this special +# exception to the GPL to apply to your modified version as well. + +#serial 5 + +AC_DEFUN([AX_CHECK_LINK_FLAG], +[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF +AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_ldflags_$4_$1])dnl +AC_CACHE_CHECK([whether the linker accepts $1], CACHEVAR, [ + ax_check_save_flags=$LDFLAGS + LDFLAGS="$LDFLAGS $4 $1" + AC_LINK_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])], + [AS_VAR_SET(CACHEVAR,[yes])], + [AS_VAR_SET(CACHEVAR,[no])]) + LDFLAGS=$ax_check_save_flags]) +AS_VAR_IF(CACHEVAR,yes, + [m4_default([$2], :)], + [m4_default([$3], :)]) +AS_VAR_POPDEF([CACHEVAR])dnl +])dnl AX_CHECK_LINK_FLAGS diff --git a/tests/utils/testapp/gen-syscall-events-callstack/Makefile.am b/tests/utils/testapp/gen-syscall-events-callstack/Makefile.am index 6e075a0df..a62d16451 100644 --- a/tests/utils/testapp/gen-syscall-events-callstack/Makefile.am +++ b/tests/utils/testapp/gen-syscall-events-callstack/Makefile.am @@ -1,5 +1,15 @@ AM_CFLAGS += -I$(top_srcdir)/tests/utils/ -AM_CFLAGS += -fno-omit-frame-pointer -no-pie +AM_CFLAGS += -fno-omit-frame-pointer +# The feature called Position Independent Execution (PIE) may be enabled by +# default on some systems. Supporting this feature for this testapp would +# increase the complexity of the testcases using this testapp as it would make +# the addresses of functions unpredictable. So we prevent the linker from +# using it by using the -no-pie option. If the -no-pie option is not +# available, we assume that the PIE is not enabled by default so we do not +# need to disable it. +if LINKER_HAVE_NO_PIE_OPTION +AM_CFLAGS += -no-pie +endif noinst_PROGRAMS = gen-syscall-events-callstack gen_syscall_events_callstack_SOURCES = gen-syscall-events-callstack.c -- 2.34.1