From patchwork Fri Jun 27 16:28:01 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joseph Myers X-Patchwork-Id: 1800 Received: (qmail 30422 invoked by alias); 27 Jun 2014 16:28:13 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 30402 invoked by uid 89); 27 Jun 2014 16:28:12 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL, BAYES_00 autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Date: Fri, 27 Jun 2014 16:28:01 +0000 From: "Joseph S. Myers" To: Subject: Remove relro configure test Message-ID: MIME-Version: 1.0 This patch removes the configure test for working -z relro. The use of -z relro in Makeconfig became unconditional with commit 2e6ab1df44c412bb9d30b26a4d8a679150a7e375 Author: Ulrich Drepper Date: Sat Oct 28 06:44:04 2006 +0000 Remove conditional code which now is unnecessary. (commit reference from git://repo.or.cz/glibc/history), so since then the configure test has not controlled anything about how glibc is built - simply about whether configure succeeds and allows a build to be attempted. The test for whether the option did something useful (as opposed to whether it exists - which we can certainly just assume by now) was originally added in to disable the option in a case when it did nothing useful on ia64 (as a result of something deliberate in the linker on ia64). Since 2006 that disabling has been of no effect, and given that the current test does not set libc_relro_required for ia64, it does nothing whatever useful for the original motivating case. Also at around the same time in 2006 the test was made to give an error for missing or broken -z relro support on various architectures. So effectively all the test does now is verify that, on certain architectures, the linker has not been changed deliberately to make the option ineffective. I see no apparent reason why such a change should be expected, or why the build should be stopped if it were to be made (any more than we disallow build on ia64); I think we can trust binutils patch review to point out the consequences of any change to COMMONPAGESIZE setting. The only thing that might now make sense would be disabling the -z relro use on an architecture-specific basis if there were an architecture-specific reason to consider that to make sense; it would be for the ia64 maintainer to decide if that makes sense for ia64 at present, but I think that could be done through sysdeps Makefiles - no special configure tests needed. Tested for x86_64 that this patch makes no change to the installed shared libraries. Together with (pending review) this substantially eliminates architecture-specific cases from architecture-independent configure.ac files. There remains an i386 case in sysdeps/mach/hurd/configure.ac that should properly move to the i386 subdirectory. (There are also OS-specific cases outside OS-specific directories; in principle I think should should also move.) 2014-06-27 Joseph Myers * configure.ac (libc_commonpagesize): Remove variable. (libc_relro_required): Likewise. (libc_cv_z_relro): Remove configure test. * configure: Regenerated. * sysdeps/aarch64/preconfigure (libc_commonpagesize): Do not set variable. (libc_relro_required): Likewise. * sysdeps/alpha/preconfigure (libc_commonpagesize): Likewise. (libc_relro_required): Likewise. * sysdeps/arm/preconfigure.ac (libc_commonpagesize): Likewise. (libc_relro_required): Likewise. * sysdeps/arm/preconfigure: Regenerated. * sysdeps/ia64/preconfigure: Remove file. * sysdeps/tile/preconfigure (libc_commonpagesize): Do not set variable. (libc_relro_required): Likewise. diff --git a/configure b/configure index ea44f64..c8d2967 100755 --- a/configure +++ b/configure @@ -5940,98 +5940,6 @@ fi { $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 $as_echo "$libc_linker_feature" >&6; } -# Add-on fragments can set these for other machines. -libc_commonpagesize=${libc_commonpagesize:-no} -libc_relro_required=${libc_relro_required:-no} -case "$base_machine" in - i[34567]86 | x86_64 | powerpc* | s390*) - libc_commonpagesize=0x1000 - libc_relro_required=yes - ;; - sparc*) - libc_commonpagesize=0x2000 - libc_relro_required=yes - ;; -esac - -if test $libc_commonpagesize != no; then - { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -z relro option" >&5 -$as_echo_n "checking for -z relro option... " >&6; } -if ${libc_cv_z_relro+:} false; then : - $as_echo_n "(cached) " >&6 -else - libc_cv_z_relro=no - cat confdefs.h - <<_ACEOF >conftest.$ac_ext -/* end confdefs.h. */ - -int _start (void) { return 42; } -extern void _exit (int); -/* Since these pointers are const, they should go in rodata. - Since they refer to functions that have to be resolved by - dynamic linking, they should instead go in RELRO data. */ -const void *const relro[] = { &_start, &_exit, 0 }; -/* GNU ld fails to produce RELRO data when it's very small and there is no - normal writable data following it, or if only uninitialized (.bss) data - follows it, or only very small writable data. */ -int data[0x10000] = { 1, }; - -_ACEOF - cat > conftest.awk <<\EOF -BEGIN { - result = "no" - commonpagesize = strtonum(commonpagesize) -} -{ print "LINE:", $0 > "/dev/stderr" } -$1 == "GNU_RELRO" { - vaddr = strtonum($3) - memsz = strtonum($6) - end = vaddr + memsz - printf "vaddr %#x memsz %#x end %#x commonpagesize %#x\n", \ - vaddr, memsz, end, commonpagesize > "/dev/stderr" - result = (end % commonpagesize == 0) ? "yes" : "broken" -} -END { print result } -EOF - { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS - -fPIC -shared -o conftest.so conftest.c - -nostartfiles -nostdlib - -Wl,-z,relro 1>&5' - { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 - (eval $ac_try) 2>&5 - ac_status=$? - $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 - test $ac_status = 0; }; } && - { ac_try='$READELF -Wl conftest.so > conftest.ph' - { { 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; }; } && - { ac_try=' - $AWK -v commonpagesize=$libc_commonpagesize -f conftest.awk - conftest.ph > conftest.cps - ' - { { 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; }; } && - libc_cv_z_relro=`cat conftest.cps 2>&5` - rm -f conftest* -fi -{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_z_relro" >&5 -$as_echo "$libc_cv_z_relro" >&6; } - if { test "x$libc_relro_required" = xyes && - test "x$libc_cv_z_relro" != xyes - } - then - as_fn_error $? "linker with -z relro support required" "$LINENO" 5 - fi -else - { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: missing architecture parameter to check for working -z relro" >&5 -$as_echo "$as_me: WARNING: missing architecture parameter to check for working -z relro" >&2;} -fi - { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -Bgroup option" >&5 $as_echo_n "checking for -Bgroup option... " >&6; } if ${libc_cv_Bgroup+:} false; then : diff --git a/configure.ac b/configure.ac index f8d7860..566ecb2 100644 --- a/configure.ac +++ b/configure.ac @@ -1342,73 +1342,6 @@ LIBC_LINKER_FEATURE([-z initfirst], [-Wl,--enable-new-dtags,-z,initfirst], [libc_cv_z_initfirst=yes], [AC_MSG_ERROR(linker with -z initfirst support required)]) -# Add-on fragments can set these for other machines. -libc_commonpagesize=${libc_commonpagesize:-no} -libc_relro_required=${libc_relro_required:-no} -case "$base_machine" in - i[[34567]]86 | x86_64 | powerpc* | s390*) - libc_commonpagesize=0x1000 - libc_relro_required=yes - ;; - sparc*) - libc_commonpagesize=0x2000 - libc_relro_required=yes - ;; -esac - -if test $libc_commonpagesize != no; then - AC_CACHE_CHECK(for -z relro option, - libc_cv_z_relro, [dnl - libc_cv_z_relro=no - AC_LANG_CONFTEST([AC_LANG_SOURCE([[ -int _start (void) { return 42; } -extern void _exit (int); -/* Since these pointers are const, they should go in rodata. - Since they refer to functions that have to be resolved by - dynamic linking, they should instead go in RELRO data. */ -const void *const relro[] = { &_start, &_exit, 0 }; -/* GNU ld fails to produce RELRO data when it's very small and there is no - normal writable data following it, or if only uninitialized (.bss) data - follows it, or only very small writable data. */ -int data[0x10000] = { 1, }; -]])]) - cat > conftest.awk <<\EOF -BEGIN { - result = "no" - commonpagesize = strtonum(commonpagesize) -} -{ print "LINE:", $0 > "/dev/stderr" } -$1 == "GNU_RELRO" { - vaddr = strtonum($3) - memsz = strtonum($6) - end = vaddr + memsz - printf "vaddr %#x memsz %#x end %#x commonpagesize %#x\n", \ - vaddr, memsz, end, commonpagesize > "/dev/stderr" - result = (end % commonpagesize == 0) ? "yes" : "broken" -} -END { print result } -EOF - AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS - -fPIC -shared -o conftest.so conftest.c - -nostartfiles -nostdlib - -Wl,-z,relro 1>&AS_MESSAGE_LOG_FD]) && - AC_TRY_COMMAND([$READELF -Wl conftest.so > conftest.ph]) && - AC_TRY_COMMAND([ - $AWK -v commonpagesize=$libc_commonpagesize -f conftest.awk - conftest.ph > conftest.cps - ]) && - libc_cv_z_relro=`cat conftest.cps 2>&AS_MESSAGE_LOG_FD` - rm -f conftest*]) - if { test "x$libc_relro_required" = xyes && - test "x$libc_cv_z_relro" != xyes - } - then - AC_MSG_ERROR(linker with -z relro support required) - fi -else - AC_MSG_WARN([missing architecture parameter to check for working -z relro]) -fi - AC_CACHE_CHECK(for -Bgroup option, libc_cv_Bgroup, [dnl cat > conftest.c <