From 63678e17cf399ff81b93417fe7bee8d6ef6b6b1b Mon Sep 17 00:00:00 2001 From: Steven Noonan Date: Fri, 28 Mar 2014 17:19:02 +0100 Subject: configure: add option to disable -fstack-protector flags 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-all, no stack protector. Signed-off-by: Steven Noonan Cc: Anthony Liguori Reviewed-by: Stefan Weil [Prefer -fstack-protector-all to -fstack-protector, suggested by Laurent Desnogues. - Paolo] Signed-off-by: Paolo Bonzini Signed-off-by: Peter Maydell --- configure | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) (limited to 'configure') diff --git a/configure b/configure index fb3bd0588f..eb0e7bbce0 100755 --- a/configure +++ b/configure @@ -198,6 +198,7 @@ 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 @@ -950,6 +951,10 @@ 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" @@ -1219,6 +1224,7 @@ Advanced options (experts only): --disable-sparse disable sparse checker (default) --disable-strip disable stripping binaries --disable-werror disable compilation abort on warning + --disable-stack-protector disable compiler-provided stack protection --disable-sdl disable SDL --enable-sdl enable SDL --with-sdlabi select preferred SDL ABI 1.2 or 2.0 @@ -1439,9 +1445,15 @@ 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-all" + 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 -- cgit v1.2.3