From c01bf42117b811a0469f9f6c374f4a0daa98716d Mon Sep 17 00:00:00 2001
From: Henrik Gramner <henrik@gramner.com>
Date: Thu, 28 Jan 2016 18:37:37 +0100
Subject: [PATCH] mingw: Enable high-entropy ASLR on 64-bit Windows

To fully utilize HEASLR the image base address must also be set above
4 GiB. For consistency use the same address as MSVC uses by default.

This requires binutils 2.25 which isn't available on all common
distributions, so only enable it after checking that it's supported.
---
 configure | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/configure b/configure
index 09643db0..0d40a927 100755
--- a/configure
+++ b/configure
@@ -693,10 +693,15 @@ case $host_cpu in
             fi
         elif [ "$SYS" = WINDOWS -o "$SYS" = CYGWIN ]; then
             ASFLAGS="$ASFLAGS -f win64"
-            # only the GNU toolchain is inconsistent in prefixing function names with _
-            [ $compiler = GNU ] && cc_check "" "-S" && grep -q "_main:" conftest && ASFLAGS="$ASFLAGS -DPREFIX"
-            [ $compiler = GNU ] && LDFLAGS="$LDFLAGS -Wl,--dynamicbase,--nxcompat,--tsaware"
-            [ $compiler = GNU ] && RCFLAGS="--target=pe-x86-64 $RCFLAGS"
+            if [ $compiler = GNU ]; then
+                # only the GNU toolchain is inconsistent in prefixing function names with _
+                cc_check "" "-S" && grep -q "_main:" conftest && ASFLAGS="$ASFLAGS -DPREFIX"
+                cc_check "" "-Wl,--high-entropy-va" && LDFLAGS="$LDFLAGS -Wl,--high-entropy-va"
+                LDFLAGS="$LDFLAGS -Wl,--dynamicbase,--nxcompat,--tsaware"
+                LDFLAGSCLI="$LDFLAGSCLI -Wl,--image-base,0x140000000"
+                SOFLAGS="$SOFLAGS -Wl,--image-base,0x180000000"
+                RCFLAGS="--target=pe-x86-64 $RCFLAGS"
+            fi
         else
             ASFLAGS="$ASFLAGS -f elf64"
         fi
@@ -1389,7 +1394,7 @@ if [ "$shared" = "yes" ]; then
             grep "extern.*x264" ${SRCPATH}/x264.h | sed -e "s/.*\(x264\w*\)\W.*/\1 DATA/;" >> x264.def
         else
             echo 'IMPLIBNAME=libx264.dll.a' >> config.mak
-            echo "SOFLAGS=-shared -Wl,--out-implib,\$(IMPLIBNAME) -Wl,--enable-auto-image-base $SOFLAGS" >> config.mak
+            echo "SOFLAGS=-shared -Wl,--out-implib,\$(IMPLIBNAME) $SOFLAGS" >> config.mak
         fi
     elif [ "$SYS" = "MACOSX" ]; then
         echo "SOSUFFIX=dylib" >> config.mak
-- 
2.39.2