configure: Implement --enable-host-pie

This patch implements the --enable-host-pie configure option which
makes the compiler executables PIE.  This can be used to enhance
protection against ROP attacks, and can be viewed as part of a wider
trend to harden binaries.

It is similar to the option --enable-host-shared, except that --e-h-s
won't add -shared to the linker flags whereas --e-h-p will add -pie.
It is different from --enable-default-pie because that option just
adds an implicit -fPIE/-pie when the compiler is invoked, but the
compiler itself isn't PIE.

Since r12-5768-gfe7c3ecf, PCH works well with PIE, so there are no PCH
regressions.

When building the compiler, the build process may use various in-tree
libraries; these need to be built with -fPIE so that it's possible to
use them when building a PIE.  For instance, when --with-included-gettext
is in effect, intl object files must be compiled with -fPIE.  Similarly,
when building in-tree gmp, isl, mpfr and mpc, they must be compiled with
-fPIE.

I plan to add an option to link with -Wl,-z,now.

ChangeLog:

	* Makefile.def: Pass $(PICFLAG) to AM_CFLAGS for gmp, mpfr, mpc, and
	isl.
	* Makefile.in: Regenerate.
	* Makefile.tpl: Set PICFLAG.
	* configure.ac (--enable-host-pie): New check.  Set PICFLAG after this
	check.
	* configure: Regenerate.

c++tools/ChangeLog:

	* Makefile.in: Rename PIEFLAG to PICFLAG.  Set LD_PICFLAG.  Use it.
	Use pic/libiberty.a if PICFLAG is set.
	* configure.ac (--enable-default-pie): Set PICFLAG instead of PIEFLAG.
	(--enable-host-pie): New check.
	* configure: Regenerate.

fixincludes/ChangeLog:

	* Makefile.in: Set and use PICFLAG and LD_PICFLAG.  Use the "pic"
	build of libiberty if PICFLAG is set.
	* configure.ac:
	* configure: Regenerate.

gcc/ChangeLog:

	* Makefile.in: Set LD_PICFLAG.  Use it.  Set enable_host_pie.
	Remove NO_PIE_CFLAGS and NO_PIE_FLAG.  Pass LD_PICFLAG to
	ALL_LINKERFLAGS.  Use the "pic" build of libiberty if --enable-host-pie.
	* configure.ac (--enable-host-shared): Don't set PICFLAG here.
	(--enable-host-pie): New check.  Set PICFLAG and LD_PICFLAG after this
	check.
	* configure: Regenerate.
	* doc/install.texi: Document --enable-host-pie.

gcc/d/ChangeLog:

	* Make-lang.in: Remove NO_PIE_CFLAGS.

intl/ChangeLog:

	* Makefile.in: Use @PICFLAG@ in COMPILE as well.
	* configure.ac (--enable-host-shared): Don't set PICFLAG here.
	(--enable-host-pie): New check.  Set PICFLAG after this check.
	* configure: Regenerate.

libcody/ChangeLog:

	* Makefile.in: Pass LD_PICFLAG to LDFLAGS.
	* configure.ac (--enable-host-shared): Don't set PICFLAG here.
	(--enable-host-pie): New check.  Set PICFLAG and LD_PICFLAG after this
	check.
	* configure: Regenerate.

libcpp/ChangeLog:

	* configure.ac (--enable-host-shared): Don't set PICFLAG here.
	(--enable-host-pie): New check.  Set PICFLAG after this check.
	* configure: Regenerate.

libdecnumber/ChangeLog:

	* configure.ac (--enable-host-shared): Don't set PICFLAG here.
	(--enable-host-pie): New check.  Set PICFLAG after this check.
	* configure: Regenerate.

libiberty/ChangeLog:

	* configure.ac: Also set shared when enable_host_pie.
	* configure: Regenerate.

zlib/ChangeLog:

	* configure.ac (--enable-host-shared): Don't set PICFLAG here.
	(--enable-host-pie): New check.  Set PICFLAG after this check.
	* configure: Regenerate.

5 files changed, 91 insertions, 39 deletions

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 5ad638f..5a78c74 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -158,6 +158,9 @@ LDFLAGS = @LDFLAGS@
 # Should we build position-independent host code?
 PICFLAG = @PICFLAG@
 
+# The linker flag for the above.
+LD_PICFLAG = @LD_PICFLAG@
+
 # Flags to determine code coverage. When coverage is disabled, this will
 # contain the optimization flags, as you normally want code coverage
 # without optimization.
@@ -266,18 +269,17 @@ LINKER = $(CC)
 LINKER_FLAGS = $(CFLAGS)
 endif
 
+enable_host_pie = @enable_host_pie@
+
 # Enable Intel CET on Intel CET enabled host if needed.
 CET_HOST_FLAGS = @CET_HOST_FLAGS@
 COMPILER += $(CET_HOST_FLAGS)
 
-NO_PIE_CFLAGS = @NO_PIE_CFLAGS@
-NO_PIE_FLAG = @NO_PIE_FLAG@
-
-# We don't want to compile the compilers with -fPIE, it make PCH fail.
-COMPILER += $(NO_PIE_CFLAGS)
+# Maybe compile the compilers with -fPIE or -fPIC.
+COMPILER += $(PICFLAG)
 
-# Link with -no-pie since we compile the compiler with -fno-PIE.
-LINKER += $(NO_PIE_FLAG)
+# Link with -pie, or -no-pie, depending on the above.
+LINKER += $(LD_PICFLAG)
 
 # Like LINKER, but use a mutex for serializing front end links.
 ifeq (@DO_LINK_MUTEX@,true)
@@ -1060,18 +1062,21 @@ ALL_CPPFLAGS = $(INCLUDES) $(CPPFLAGS)
 ALL_COMPILERFLAGS = $(ALL_CXXFLAGS)
 
 # This is the variable to use when using $(LINKER).
-ALL_LINKERFLAGS = $(ALL_CXXFLAGS)
+ALL_LINKERFLAGS = $(ALL_CXXFLAGS) $(LD_PICFLAG)
 
 # Build and host support libraries.
 
-# Use the "pic" build of libiberty if --enable-host-shared, unless we are
-# building for mingw.
+# Use the "pic" build of libiberty if --enable-host-shared or --enable-host-pie,
+# unless we are building for mingw.
 LIBIBERTY_PICDIR=$(if $(findstring mingw,$(target)),,pic)
-ifeq ($(enable_host_shared),yes)
+ifneq ($(enable_host_shared)$(enable_host_pie),)
 LIBIBERTY = ../libiberty/$(LIBIBERTY_PICDIR)/libiberty.a
-BUILD_LIBIBERTY = $(build_libobjdir)/libiberty/$(LIBIBERTY_PICDIR)/libiberty.a
 else
 LIBIBERTY = ../libiberty/libiberty.a
+endif
+ifeq ($(enable_host_shared),yes)
+BUILD_LIBIBERTY = $(build_libobjdir)/libiberty/$(LIBIBERTY_PICDIR)/libiberty.a
+else
 BUILD_LIBIBERTY = $(build_libobjdir)/libiberty/libiberty.a
 endif
 
diff --git a/gcc/configure b/gcc/configure
index aa09609..f631830 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -632,10 +632,10 @@ ac_includes_default="\
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
 CET_HOST_FLAGS
-NO_PIE_FLAG
-NO_PIE_CFLAGS
-enable_default_pie
+LD_PICFLAG
 PICFLAG
+enable_default_pie
+enable_host_pie
 enable_host_shared
 enable_plugin
 pluginlibs
@@ -1025,6 +1025,7 @@ enable_link_serialization
 enable_version_specific_runtime_libs
 enable_plugin
 enable_host_shared
+enable_host_pie
 enable_libquadmath_support
 with_linker_hash_style
 with_diagnostics_color
@@ -1787,6 +1788,7 @@ Optional Features:
                           in a compiler-specific directory
   --enable-plugin         enable plugin support
   --enable-host-shared    build host code as shared libraries
+  --enable-host-pie       build host code as PIE
   --disable-libquadmath-support
                           disable libquadmath support for Fortran
   --enable-default-pie    enable Position Independent Executable as default
@@ -19710,7 +19712,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 19713 "configure"
+#line 19727 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -19816,7 +19818,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 19819 "configure"
+#line 19833 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -31945,13 +31947,17 @@ fi
 # Enable --enable-host-shared
 # Check whether --enable-host-shared was given.
 if test "${enable_host_shared+set}" = set; then :
-  enableval=$enable_host_shared; PICFLAG=-fPIC
-else
-  PICFLAG=
+  enableval=$enable_host_shared;
 fi
 
 
 
+# Enable --enable-host-pie
+# Check whether --enable-host-pie was given.
+if test "${enable_host_pie+set}" = set; then :
+  enableval=$enable_host_pie;
+fi
+
 
 
 # Check whether --enable-libquadmath-support was given.
@@ -32105,10 +32111,6 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
 fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_c_no_fpie" >&5
 $as_echo "$gcc_cv_c_no_fpie" >&6; }
-if test "$gcc_cv_c_no_fpie" = "yes"; then
-  NO_PIE_CFLAGS="-fno-PIE"
-fi
-
 
 # Check if -no-pie works.
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for -no-pie option" >&5
@@ -32133,11 +32135,28 @@ rm -f core conftest.err conftest.$ac_objext \
 fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $gcc_cv_no_pie" >&5
 $as_echo "$gcc_cv_no_pie" >&6; }
-if test "$gcc_cv_no_pie" = "yes"; then
-  NO_PIE_FLAG="-no-pie"
+
+if test x$enable_host_shared = xyes; then
+  PICFLAG=-fPIC
+elif test x$enable_host_pie = xyes; then
+  PICFLAG=-fPIE
+elif test x$gcc_cv_c_no_fpie = xyes; then
+  PICFLAG=-fno-PIE
+else
+  PICFLAG=
+fi
+
+if test x$enable_host_pie = xyes; then
+  LD_PICFLAG=-pie
+elif test x$gcc_cv_no_pie = xyes; then
+  LD_PICFLAG=-no-pie
+else
+  LD_PICFLAG=
 fi
 
 
+
+
 # Enable Intel CET on Intel CET enabled host if jit is enabled.
  # Check whether --enable-cet was given.
 if test "${enable_cet+set}" = set; then :
diff --git a/gcc/configure.ac b/gcc/configure.ac
index 7c55bff..f5b23b9 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -7364,11 +7364,14 @@ fi
 # Enable --enable-host-shared
 AC_ARG_ENABLE(host-shared,
 [AS_HELP_STRING([--enable-host-shared],
-		[build host code as shared libraries])],
-[PICFLAG=-fPIC], [PICFLAG=])
+		[build host code as shared libraries])])
 AC_SUBST(enable_host_shared)
-AC_SUBST(PICFLAG)
 
+# Enable --enable-host-pie
+AC_ARG_ENABLE(host-pie,
+[AS_HELP_STRING([--enable-host-pie],
+		[build host code as PIE])])
+AC_SUBST(enable_host_pie)
 
 AC_ARG_ENABLE(libquadmath-support,
 [AS_HELP_STRING([--disable-libquadmath-support],
@@ -7490,10 +7493,6 @@ AC_CACHE_CHECK([for -fno-PIE option],
      [gcc_cv_c_no_fpie=yes],
      [gcc_cv_c_no_fpie=no])
    CXXFLAGS="$saved_CXXFLAGS"])
-if test "$gcc_cv_c_no_fpie" = "yes"; then
-  NO_PIE_CFLAGS="-fno-PIE"
-fi
-AC_SUBST([NO_PIE_CFLAGS])
 
 # Check if -no-pie works.
 AC_CACHE_CHECK([for -no-pie option],
@@ -7504,10 +7503,27 @@ AC_CACHE_CHECK([for -no-pie option],
      [gcc_cv_no_pie=yes],
      [gcc_cv_no_pie=no])
    LDFLAGS="$saved_LDFLAGS"])
-if test "$gcc_cv_no_pie" = "yes"; then
-  NO_PIE_FLAG="-no-pie"
+
+if test x$enable_host_shared = xyes; then
+  PICFLAG=-fPIC
+elif test x$enable_host_pie = xyes; then
+  PICFLAG=-fPIE
+elif test x$gcc_cv_c_no_fpie = xyes; then
+  PICFLAG=-fno-PIE
+else
+  PICFLAG=
 fi
-AC_SUBST([NO_PIE_FLAG])
+
+if test x$enable_host_pie = xyes; then
+  LD_PICFLAG=-pie
+elif test x$gcc_cv_no_pie = xyes; then
+  LD_PICFLAG=-no-pie
+else
+  LD_PICFLAG=
+fi
+
+AC_SUBST([PICFLAG])
+AC_SUBST([LD_PICFLAG])
 
 # Enable Intel CET on Intel CET enabled host if jit is enabled.
 GCC_CET_HOST_FLAGS(CET_HOST_FLAGS)
diff --git a/gcc/d/Make-lang.in b/gcc/d/Make-lang.in
index 6f9b2e5..dff0649 100644
--- a/gcc/d/Make-lang.in
+++ b/gcc/d/Make-lang.in
@@ -64,7 +64,7 @@ ALL_DFLAGS = $(DFLAGS-$@) $(GDCFLAGS) -fversion=IN_GCC $(CHECKING_DFLAGS) \
 	$(PICFLAG) $(ALIASING_FLAGS) $(NOEXCEPTION_DFLAGS) $(COVERAGE_FLAGS) \
 	$(WARN_DFLAGS)
 
-DCOMPILE.base = $(GDC) $(NO_PIE_CFLAGS) -c $(ALL_DFLAGS) -o $@
+DCOMPILE.base = $(GDC) -c $(ALL_DFLAGS) -o $@
 DCOMPILE = $(DCOMPILE.base) -MT $@ -MMD -MP -MF $(@D)/$(DEPDIR)/$(*F).TPo
 DPOSTCOMPILE = @mv $(@D)/$(DEPDIR)/$(*F).TPo $(@D)/$(DEPDIR)/$(*F).Po
 DLINKER = $(GDC) $(NO_PIE_FLAG) -lstdc++
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 589c649..b91fbe0 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -1026,14 +1026,26 @@ code.
 
 @item --enable-host-shared
 Specify that the @emph{host} code should be built into position-independent
-machine code (with -fPIC), allowing it to be used within shared libraries,
-but yielding a slightly slower compiler.
+machine code (with @option{-fPIC}), allowing it to be used within shared
+libraries, but yielding a slightly slower compiler.
 
 This option is required when building the libgccjit.so library.
 
 Contrast with @option{--enable-shared}, which affects @emph{target}
 libraries.
 
+@item --enable-host-pie
+Specify that the @emph{host} executables should be built into
+position-independent executables (with @option{-fPIE} and @option{-pie}),
+yielding a slightly slower compiler (but faster than
+@option{--enable-host-shared}).  Position-independent executables are loaded
+at random addresses each time they are executed, therefore provide additional
+protection against Return Oriented Programming (ROP) attacks.
+
+@option{--enable-host-pie}) may be used with @option{--enable-host-shared}),
+in which case @option{-fPIC} is used when compiling, and @option{-pie} when
+linking.
+
 @item @anchor{with-gnu-as}--with-gnu-as
 Specify that the compiler should assume that the
 assembler it finds is the GNU assembler.  However, this does not modify