From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44319) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WB6eh-00078m-6C for qemu-devel@nongnu.org; Wed, 05 Feb 2014 12:53:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WB6ec-0006io-HN for qemu-devel@nongnu.org; Wed, 05 Feb 2014 12:52:59 -0500 Received: from mail-qc0-x22e.google.com ([2607:f8b0:400d:c01::22e]:60626) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WB6ec-0006ib-At for qemu-devel@nongnu.org; Wed, 05 Feb 2014 12:52:54 -0500 Received: by mail-qc0-f174.google.com with SMTP id x13so1201115qcv.33 for ; Wed, 05 Feb 2014 09:52:53 -0800 (PST) Sender: Paolo Bonzini Message-ID: <52F27A71.2030609@redhat.com> Date: Wed, 05 Feb 2014 18:52:49 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1389645412-2249-1-git-send-email-snoonan@amazon.com> In-Reply-To: <1389645412-2249-1-git-send-email-snoonan@amazon.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v3] configure: add option to disable -fstack-protector flags List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Steven Noonan , qemu-devel@nongnu.org Cc: Steven Noonan , Anthony Liguori Il 13/01/2014 21:36, Steven Noonan ha scritto: > The -fstack-protector flag family is useful for ensuring safety and for > debugging, but has a performance impact. Here are some boot time comparisons of > the various versions of -fstack-protector using qemu-system-arm on an x86_64 > host: > > # -fstack-protector-all > Startup finished in 1.810s (kernel) + 12.331s (initrd) + 49.016s (userspace) = 1min 3.159s > Startup finished in 1.801s (kernel) + 12.287s (initrd) + 47.925s (userspace) = 1min 2.013s > Startup finished in 1.812s (kernel) + 12.302s (initrd) + 47.995s (userspace) = 1min 2.111s > > # -fstack-protector-strong > Startup finished in 1.744s (kernel) + 11.223s (initrd) + 44.688s (userspace) = 57.657s > Startup finished in 1.721s (kernel) + 11.222s (initrd) + 44.194s (userspace) = 57.138s > Startup finished in 1.693s (kernel) + 11.250s (initrd) + 44.426s (userspace) = 57.370s > > # -fstack-protector > Startup finished in 1.705s (kernel) + 11.409s (initrd) + 43.563s (userspace) = 56.677s > Startup finished in 1.877s (kernel) + 11.137s (initrd) + 43.719s (userspace) = 56.734s > Startup finished in 1.708s (kernel) + 11.141s (initrd) + 43.628s (userspace) = 56.478s > > # no stack protector > Startup finished in 1.743s (kernel) + 11.190s (initrd) + 43.709s (userspace) = 56.643s > Startup finished in 1.763s (kernel) + 11.216s (initrd) + 43.767s (userspace) = 56.747s > Startup finished in 1.711s (kernel) + 11.283s (initrd) + 43.878s (userspace) = 56.873s > > This patch introduces a configure option to disable the stack protector > entirely, and conditional stack protector flag selection (in order, based on > availability): -fstack-protector-strong, -fstack-protector, no stack protector. > > Signed-off-by: Steven Noonan > Cc: Anthony Liguori > Reviewed-by: Stefan Weil > --- > configure | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > > diff --git a/configure b/configure > index 07b6be3..09f83a7 100755 > --- a/configure > +++ b/configure > @@ -147,6 +147,7 @@ audio_win_int="" > cc_i386=i386-pc-linux-gnu-gcc > libs_qga="" > debug_info="yes" > +stack_protector="" > > # Don't accept a target_list environment variable. > unset target_list > @@ -879,6 +880,10 @@ for opt do > ;; > --disable-werror) werror="no" > ;; > + --enable-stack-protector) stack_protector="yes" > + ;; > + --disable-stack-protector) stack_protector="no" > + ;; > --disable-curses) curses="no" > ;; > --enable-curses) curses="yes" > @@ -1117,6 +1122,7 @@ echo " --enable-sparse enable sparse checker" > echo " --disable-sparse disable sparse checker (default)" > echo " --disable-strip disable stripping binaries" > echo " --disable-werror disable compilation abort on warning" > +echo " --disable-stack-protector disable compiler-provided stack protection" > echo " --disable-sdl disable SDL" > echo " --enable-sdl enable SDL" > echo " --disable-gtk disable gtk UI" > @@ -1298,9 +1304,15 @@ for flag in $gcc_flags; do > fi > done > > -if compile_prog "-Werror -fstack-protector-all" "" ; then > - QEMU_CFLAGS="$QEMU_CFLAGS -fstack-protector-all" > - LIBTOOLFLAGS="$LIBTOOLFLAGS -Wc,-fstack-protector-all" > +if test "$stack_protector" != "no" ; then > + gcc_flags="-fstack-protector-strong -fstack-protector" > + for flag in $gcc_flags; do > + if compile_prog "-Werror $flag" "" ; then > + QEMU_CFLAGS="$QEMU_CFLAGS $flag" > + LIBTOOLFLAGS="$LIBTOOLFLAGS -Wc,$flag" > + break > + fi > + done > fi > > # Workaround for http://gcc.gnu.org/PR55489. Happens with -fPIE/-fPIC and > I'll apply this to my configure branch as soon as I can test it, which will likely be tomorrow or friday. Paolo