From 4d3e13ce3849bc1c5e9ce3b4ab6f40f0b37f2bfe Mon Sep 17 00:00:00 2001
From: Miroslav Rezanina <mrezanin@redhat.com>
Date: Wed, 5 Feb 2014 15:02:19 +0100
Subject: configure: add option to disable -fstack-protect

RH-Author: Miroslav Rezanina <mrezanin@redhat.com>
Message-id: <fbd17542d86a4fd4beb4d9c672df14f237b51a62.1391612088.git.mrezanin@redhat.com>
Patchwork-id: 57118
O-Subject: [RHEL7 qemu-kvm PATCH 1/2] configure: add option to disable -fstack-protect
Bugzilla: 1044182
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
RH-Acked-by: Marcel Apfelbaum <marcel.a@redhat.com>
RH-Acked-by: Markus Armbruster <armbru@redhat.com>

From: Miroslav Rezanina <mrezanin@redhat.com>

upstream: submitted
(Do not wait for apply to get to RHEL 7.0 before Snapshot 8)

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>
Cc: Anthony Liguori <address@hidden>
Reviewed-by: Stefan Weil <address@hidden>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

diff --git a/configure b/configure
index 3cb1298..bebae4c 100755
--- a/configure
+++ b/configure
@@ -1281,6 +1281,7 @@ Advanced options (experts only):
   --disable-strip          disable stripping binaries
   --disable-werror         disable compilation abort on warning
   --disable-stack-protector disable compiler-provided stack protection
+  --enable-stack-protector enable compiler-provided stack protection
   --disable-sdl            disable SDL
   --enable-sdl             enable SDL
   --with-sdlabi            select preferred SDL ABI 1.2 or 2.0