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Re: [Qemu-devel] [PATCH] configure: add option to disable -fstack-protec
From: |
Stefan Weil |
Subject: |
Re: [Qemu-devel] [PATCH] configure: add option to disable -fstack-protector flags |
Date: |
Mon, 13 Jan 2014 21:27:42 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux i686; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 |
Hi,
please see comments below.
Am 13.01.2014 21:00, schrieb Steven Noonan:
> 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 <address@hidden>
> ---
> configure | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/configure b/configure
> index 07b6be3..c9c0b2c 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 GCC-provided stack protection"
Clang also supports stack protection AFAIK, so "GCC-provided" can be
removed here (or replaced by "compiler").
> 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
>
Reviewed-by: Stefan Weil <address@hidden>
I think this patch can be used as a base for further improvements (MinGW
specific settings, error handling when user's choice does not work).
Maybe you will have to resend the patch as a top level patch (don't use
the reply function of your mailer). As Paolo said, Anthony might
overwise be unable to pick it up with his scripts.
Regards
Stefan
- Re: [Qemu-devel] [PATCH 3/3] Makefile: add bios-256k.bin to BLOBS, (continued)
Re: [Qemu-devel] [PATCH 1/3] configure: add option to disable -fstack-protector flags, Peter Maydell, 2014/01/09
Re: [Qemu-devel] [PATCH 1/3] configure: add option to disable -fstack-protector flags, Paolo Bonzini, 2014/01/09
- Re: [Qemu-devel] [PATCH 1/3] configure: add option to disable -fstack-protector flags, Brad Smith, 2014/01/09
- Re: [Qemu-devel] [PATCH 1/3] configure: add option to disable -fstack-protector flags, Noonan, Steven, 2014/01/10
- Re: [Qemu-devel] [PATCH 1/3] configure: add option to disable -fstack-protector flags, Noonan, Steven, 2014/01/10
- Re: [Qemu-devel] [PATCH 1/3] configure: add option to disable -fstack-protector flags, Stefan Weil, 2014/01/11
- Re: [Qemu-devel] [PATCH 1/3] configure: add option to disable -fstack-protector flags, Paolo Bonzini, 2014/01/13
- [Qemu-devel] [PATCH] configure: add option to disable -fstack-protector flags, Steven Noonan, 2014/01/13
- Re: [Qemu-devel] [PATCH] configure: add option to disable -fstack-protector flags,
Stefan Weil <=
- Re: [Qemu-devel] [PATCH] configure: add option to disable -fstack-protector flags, Noonan, Steven, 2014/01/13