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From d43267efbe5634bfe9c8ca9cccd3d3d0a36759ae Mon Sep 17 00:00:00 2001
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From: Miroslav Rezanina <mrezanin@redhat.com>
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Date: Wed, 5 Feb 2014 15:02:19 +0100
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Subject: [PATCH 09/28] configure: add option to disable -fstack-protect
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RH-Author: Miroslav Rezanina <mrezanin@redhat.com>
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Message-id: <fbd17542d86a4fd4beb4d9c672df14f237b51a62.1391612088.git.mrezanin@redhat.com>
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Patchwork-id: 57118
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O-Subject: [RHEL7 qemu-kvm PATCH 1/2] configure: add option to disable -fstack-protect
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Bugzilla: 1044182
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Marcel Apfelbaum <marcel.a@redhat.com>
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RH-Acked-by: Markus Armbruster <armbru@redhat.com>
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From: Miroslav Rezanina <mrezanin@redhat.com>
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upstream: submitted
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(Do not wait for apply to get to RHEL 7.0 before Snapshot 8)
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The -fstack-protector flag family is useful for ensuring safety and for
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debugging, but has a performance impact. Here are some boot time comparisons
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of the various versions of -fstack-protector using qemu-system-arm on an
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x86_64 host:
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    # -fstack-protector-all
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    Startup finished in 1.810s (kernel) + 12.331s (initrd) + 49.016s
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(userspace) = 1min 3.159s
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    Startup finished in 1.801s (kernel) + 12.287s (initrd) + 47.925s
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(userspace) = 1min 2.013s
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    Startup finished in 1.812s (kernel) + 12.302s (initrd) + 47.995s
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(userspace) = 1min 2.111s
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    # -fstack-protector-strong
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    Startup finished in 1.744s (kernel) + 11.223s (initrd) + 44.688s
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(userspace) = 57.657s
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    Startup finished in 1.721s (kernel) + 11.222s (initrd) + 44.194s
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(userspace) = 57.138s
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    Startup finished in 1.693s (kernel) + 11.250s (initrd) + 44.426s
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(userspace) = 57.370s
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    # -fstack-protector
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    Startup finished in 1.705s (kernel) + 11.409s (initrd) + 43.563s
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(userspace) = 56.677s
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    Startup finished in 1.877s (kernel) + 11.137s (initrd) + 43.719s
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(userspace) = 56.734s
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    Startup finished in 1.708s (kernel) + 11.141s (initrd) + 43.628s
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(userspace) = 56.478s
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    # no stack protector
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    Startup finished in 1.743s (kernel) + 11.190s (initrd) + 43.709s
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(userspace) = 56.643s
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    Startup finished in 1.763s (kernel) + 11.216s (initrd) + 43.767s
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(userspace) = 56.747s
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    Startup finished in 1.711s (kernel) + 11.283s (initrd) + 43.878s
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(userspace) = 56.873s
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This patch introduces a configure option to disable the stack protector
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entirely, and conditional stack protector flag selection (in order, based on
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availability): -fstack-protector-strong, -fstack-protector, no stack protector.
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Signed-off-by: Steven Noonan <address@hidden>
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Cc: Anthony Liguori <address@hidden>
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Reviewed-by: Stefan Weil <address@hidden>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 configure | 18 +++++++++++++++---
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 1 file changed, 15 insertions(+), 3 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 configure |   18 +++++++++++++++---
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 1 files changed, 15 insertions(+), 3 deletions(-)
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diff --git a/configure b/configure
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index b892b88..3f68220 100755
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--- a/configure
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+++ b/configure
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@@ -134,6 +134,7 @@ audio_win_int=""
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 cc_i386=i386-pc-linux-gnu-gcc
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 libs_qga=""
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 debug_info="yes"
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+stack_protector=""
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 # Don't accept a target_list environment variable.
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 unset target_list
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@@ -839,6 +840,10 @@ for opt do
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   ;;
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   --disable-werror) werror="no"
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   ;;
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+  --enable-stack-protector) stack_protector="yes"
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+  ;;
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+  --disable-stack-protector) stack_protector="no"
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+  ;;
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   --disable-curses) curses="no"
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   ;;
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   --enable-curses) curses="yes"
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@@ -1115,6 +1120,7 @@ echo "  --enable-sparse          enable sparse checker"
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 echo "  --disable-sparse         disable sparse checker (default)"
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 echo "  --disable-strip          disable stripping binaries"
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 echo "  --disable-werror         disable compilation abort on warning"
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+echo "  --disable-stack-protector disable compiler-provided stack protection"
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 echo "  --disable-sdl            disable SDL"
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 echo "  --enable-sdl             enable SDL"
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 echo "  --disable-gtk            disable gtk UI"
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@@ -1296,9 +1302,15 @@ for flag in $gcc_flags; do
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     fi
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 done
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-if compile_prog "-Werror -fstack-protector-all" "" ; then
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-    QEMU_CFLAGS="$QEMU_CFLAGS -fstack-protector-all"
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-    LIBTOOLFLAGS="$LIBTOOLFLAGS -Wc,-fstack-protector-all"
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+if test "$stack_protector" != "no" ; then
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+  gcc_flags="-fstack-protector-strong -fstack-protector"
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+  for flag in $gcc_flags; do
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+    if compile_prog "-Werror $flag" "" ; then
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+      QEMU_CFLAGS="$QEMU_CFLAGS $flag"
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+      LIBTOOLFLAGS="$LIBTOOLFLAGS -Wc,$flag"
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+      break
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+    fi
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+  done
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 fi
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 # Workaround for http://gcc.gnu.org/PR55489.  Happens with -fPIE/-fPIC and
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-- 
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1.7.1
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