gcc/config/cet.m4
H.J. Lu 8fc8bf801e Enable Intel CET in liblto_plugin.so on Intel CET enabled host
Since ld is Intel CET enabled on Intel CET enabled host, dlopen fails on
liblto_plugin.so if it isn't Intel CET enabled.  Add GCC_CET_HOST_FLAGS
to cet.m4, use it in libiberty and lto-plugin to always enable Intel
CET in liblto_plugin.so on Intel CET enabled host.

On Linux/x86 host, enable Intel CET by default if assembler and compiler
support Intel CET so that the generated liblto_plugin.so can be used on
both CET and non-CET machines.  It is an error to disable Intel CET in
liblto_plugin.so on Intel CET enabled host.

config/

	PR bootstrap/94739
	* cet.m4 (GCC_CET_HOST_FLAGS): New.

libiberty/

	PR bootstrap/94739
	* Makefile.in (COMPILE.c): Add @CET_HOST_FLAGS@.
	(configure_deps): Add $(srcdir)/../config/cet.m4 and
	$(srcdir)/../config/enable.m4.
	* aclocal.m4: Include ../config/cet.m4 and ../config/enable.m4.
	* configure.ac: Add GCC_CET_HOST_FLAGS(CET_HOST_FLAGS) and
	AC_SUBST(CET_HOST_FLAGS).
	* configure: Regenerated.

lto-plugin/

	PR bootstrap/94739
	* Makefile.am (AM_CFLAGS): Add $(CET_HOST_FLAGS).
	* configure.ac: Add GCC_CET_HOST_FLAGS(CET_HOST_FLAGS) and
	AC_SUBST(CET_HOST_FLAGS).
	* Makefile.in: Regenerated.
	* aclocal.m4: Likewise.
	* configure: Likewise.
2020-04-25 10:07:16 -07:00

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dnl
dnl GCC_CET_FLAGS
dnl (SHELL-CODE_HANDLER)
dnl
AC_DEFUN([GCC_CET_FLAGS],[dnl
GCC_ENABLE(cet, no, ,[enable Intel CET in target libraries],
permit yes|no|auto)
AC_MSG_CHECKING([for CET support])
case "$host" in
i[[34567]]86-*-linux* | x86_64-*-linux*)
case "$enable_cet" in
auto)
# Check if target supports multi-byte NOPs
# and if assembler supports CET insn.
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[],
[
#if !defined(__SSE2__)
#error target does not support multi-byte NOPs
#else
asm ("setssbsy");
#endif
])],
[enable_cet=yes],
[enable_cet=no])
;;
yes)
# Check if assembler supports CET.
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[],
[asm ("setssbsy");])],
[],
[AC_MSG_ERROR([assembler with CET support is required for --enable-cet])])
;;
esac
;;
*)
enable_cet=no
;;
esac
if test x$enable_cet = xyes; then
$1="-fcf-protection -mshstk"
AC_MSG_RESULT([yes])
else
AC_MSG_RESULT([no])
fi
])
dnl
dnl GCC_CET_HOST_FLAGS
dnl (SHELL-CODE_HANDLER)
dnl
AC_DEFUN([GCC_CET_HOST_FLAGS],[dnl
GCC_ENABLE(cet, auto, ,[enable Intel CET in host libraries],
permit yes|no|auto)
AC_MSG_CHECKING([for CET support])
case "$host" in
i[[34567]]86-*-linux* | x86_64-*-linux*)
may_have_cet=yes
save_CFLAGS="$CFLAGS"
CFLAGS="$CFLAGS -fcf-protection"
case "$enable_cet" in
auto)
# Check if target supports multi-byte NOPs
# and if assembler supports CET insn.
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[],
[
#if !defined(__SSE2__)
#error target does not support multi-byte NOPs
#else
asm ("setssbsy");
#endif
])],
[enable_cet=yes],
[enable_cet=no])
;;
yes)
# Check if assembler supports CET.
AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[],
[asm ("setssbsy");])],
[],
[AC_MSG_ERROR([assembler with CET support is required for --enable-cet])])
;;
esac
CFLAGS="$save_CFLAGS"
;;
*)
may_have_cet=no
enable_cet=no
;;
esac
if test x$may_have_cet = xyes; then
save_LDFLAGS="$LDFLAGS"
LDFLAGS="$LDFLAGS -Wl,-z,ibt,-z,shstk"
AC_TRY_RUN([
static void
foo (void)
{
}
static void
__attribute__ ((noinline, noclone))
xxx (void (*f) (void))
{
f ();
}
static void
__attribute__ ((noinline, noclone))
bar (void)
{
xxx (foo);
}
int
main ()
{
bar ();
return 0;
}
],
[have_cet=no],
[have_cet=yes])
LDFLAGS="$save_LDFLAGS"
if test x$enable_cet = xno -a x$have_cet = xyes; then
AC_MSG_ERROR([Intel CET must be enabled on Intel CET enabled host])
fi
fi
if test x$enable_cet = xyes; then
$1="-fcf-protection"
AC_MSG_RESULT([yes])
else
AC_MSG_RESULT([no])
fi
])