Bug 892355 - Force enable elfhack with --enable-elf-hack. r=ted

browser/config/mozconfigs/linux32/nightly

@@ -3,6 +3,7 @@
 ac_add_options --enable-codesighs
 ac_add_options --enable-signmar
 ac_add_options --enable-profiling
+ac_add_options --disable-elf-hack # --enable-elf-hack conflicts with --enable-profiling
 
 # Nightlies only since this has a cost in performance
 ac_add_options --enable-js-diagnostics

browser/config/mozconfigs/linux64/nightly

@@ -3,6 +3,7 @@
 ac_add_options --enable-codesighs
 ac_add_options --enable-signmar
 ac_add_options --enable-profiling
+ac_add_options --disable-elf-hack # --enable-elf-hack conflicts with --enable-profiling
 
 # Nightlies only since this has a cost in performance
 ac_add_options --enable-js-diagnostics

build/unix/mozconfig.linux

@@ -2,3 +2,5 @@
 
 CC="/tools/gcc-4.7.2-0moz1/bin/gcc"
 CXX="/tools/gcc-4.7.2-0moz1/bin/g++"
+
+ac_add_options --enable-elf-hack

configure.in

@@ -7566,13 +7566,16 @@ dnl ========================================================
 USE_ELF_HACK=1
 MOZ_ARG_DISABLE_BOOL(elf-hack,
 [  --disable-elf-hack      Disable elf hacks],
-    USE_ELF_HACK=,
-    USE_ELF_HACK=1)
+    [USE_ELF_HACK=],
+    [USE_ELF_HACK=F # Force enable elf-hack])
 
 # Disable elf hack for profiling because the built in profiler
 # doesn't read the segments properly with elf hack. This is
 # temporary and should be fixed soon in the profiler.
 if test "$MOZ_PROFILING" = 1; then
+  if test "$USE_ELF_HACK" = F; then
+    AC_ERROR([--enable-elf-hack is not compatible with --enable-profiling])
+  fi
   USE_ELF_HACK=
 fi
 
@@ -7595,7 +7598,7 @@ if test "$USE_ELF_HACK" = 1; then
     esac
 fi
 
-if test "$USE_ELF_HACK" = 1; then
+if test -n "$USE_ELF_HACK"; then
     dnl PT_GNU_RELRO segment makes the dynamic linker set a read-only flag on
     dnl memory addresses it maps to. The result is that by the time elfhack
     dnl kicks in, it is not possible to apply relocations because of that,
@@ -7603,7 +7606,8 @@ if test "$USE_ELF_HACK" = 1; then
     dnl segment. It makes elfhack mostly useless, so considering the problems
     dnl we have we PT_GNU_RELRO (e.g. bug 664366), and until elfhack can deal
     dnl with PT_GNU_RELRO segments, it's just simpler to disable elfhack when
-    dnl the linker creates PT_GNU_RELRO segments.
+    dnl the linker creates PT_GNU_RELRO segments. However, when we do want
+    dnl elfhack enabled, disable PT_GNU_RELRO instead.
     AC_CACHE_CHECK([whether linker creates PT_GNU_RELRO segments],
         LINK_WITH_PT_GNU_RELRO,
         [echo "int main() {return 0;}" > conftest.${ac_ext}
@@ -7620,8 +7624,18 @@ if test "$USE_ELF_HACK" = 1; then
          fi
          rm -rf conftest*])
     if test "$LINK_WITH_PT_GNU_RELRO" = yes; then
-        AC_MSG_WARN([Disabling elfhack])
-        USE_ELF_HACK=
+        if test "$USE_ELF_HACK" = F; then
+            AC_MSG_CHECKING([for -z norelro option to ld])
+            _SAVE_LDFLAGS=$LDFLAGS
+            LDFLAGS="$LDFLAGS -Wl,-z,norelro"
+            AC_TRY_LINK(,,AC_MSG_RESULT([yes])
+                        [NSPR_LDFLAGS="$NSPR_LDFLAGS -Wl,-z,norelro"],
+                        AC_ERROR([--enable-elf-hack is not compatible with a linker creating a PT_GNU_RELRO segment and that doesn't support the "-z norelro" option.]))
+            USE_ELF_HACK=1
+        else
+            AC_MSG_WARN([Disabling elfhack])
+            USE_ELF_HACK=
+        fi
     fi
 fi
 

mobile/android/config/mozconfigs/android/nightly

@@ -19,6 +19,7 @@ ac_add_options --with-android-version=9
 ac_add_options --with-system-zlib
 ac_add_options --enable-update-channel=${MOZ_UPDATE_CHANNEL}
 ac_add_options --enable-profiling
+ac_add_options --disable-elf-hack # --enable-elf-hack conflicts with --enable-profiling
 
 export JAVA_HOME=/tools/jdk6
 export MOZILLA_OFFICIAL=1

mobile/android/config/mozconfigs/common

@@ -10,3 +10,5 @@
 # much slower and we didn't want to slow down developers builds.
 # Has no effect when MOZ_ENABLE_SZIP is not set in mobile/android/confvars.sh.
 MOZ_SZIP_FLAGS="-D auto -f auto"
+
+ac_add_options --enable-elf-hack