diff options
| -rw-r--r-- | erts/configure.in | 50 | ||||
| -rw-r--r-- | erts/emulator/beam/beam_emu.c | 1 |
2 files changed, 51 insertions, 0 deletions
diff --git a/erts/configure.in b/erts/configure.in index ad9a66126f..4d1464d744 100644 --- a/erts/configure.in +++ b/erts/configure.in @@ -416,6 +416,56 @@ if test X"$with_ets_write_concurrency_locks" != X""; then [Define to override the default number of write_concurrency locks]) fi +AC_ARG_WITH(spectre-mitigation, + AS_HELP_STRING([--with-spectre-mitigation={yes|incomplete}], + [enable spectre mitigation, either fully or with mitigations + disabled in a handful places like the interpreter]) + AS_HELP_STRING([--without-spectre-mitigation], + [build without spectre mitigation]), + [],[with_spectre_mitigation=no]) + +case "$with_spectre_mitigation" in + no) ;; + yes) ;; + incomplete) ;; + *) AC_MSG_ERROR([Invalid spectre mitigation setting]) ;; +esac + +i_noretpoline_attr="" + +if test X"$with_spectre_mitigation" != X"no"; then + CFLAGS="$CFLAGS -mindirect-branch=thunk" + + AC_MSG_CHECKING([for spectre mitigation]) + AC_COMPILE_IFELSE( + [AC_LANG_PROGRAM([],[return 0;])], + [AC_MSG_RESULT([yes])], + [AC_MSG_ERROR([no])]) + + if test X"$with_spectre_mitigation" = X"incomplete"; then + # gcc and clang support this attribute if they're recent enough. Note + # that we must compile with -Werror to check for actual support as they + # warn rather than error out on unsupported attributes. + + i_noretpoline_attr='__attribute__((__indirect_branch__("keep")))' + i_preserve_cflags="$CFLAGS" + CFLAGS="$CFLAGS -Werror" + + AC_MSG_CHECKING([whether spectre mitigation can be disabled on a per-function basis]) + AC_COMPILE_IFELSE( + [AC_LANG_PROGRAM([$i_noretpoline_attr],[return 0;])], + [AC_MSG_RESULT([yes])], + [AC_MSG_ERROR([no])]) + + CFLAGS="$i_preserve_cflags" + fi +fi + +AC_DEFINE_UNQUOTED(ERTS_NO_RETPOLINE, $i_noretpoline_attr, + [Per-function attribute for disabling retpoline. This is + *only* defined when --with-spectre-mitigation=incomplete + and has no effects otherwise]) + dnl ---------------------------------------------------------------------- dnl Checks for programs. dnl ---------------------------------------------------------------------- diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c index 1ad13c32e3..0f6e6533fc 100644 --- a/erts/emulator/beam/beam_emu.c +++ b/erts/emulator/beam/beam_emu.c @@ -1227,6 +1227,7 @@ init_emulator(void) * the instructions' C labels to the loader. * The second call starts execution of BEAM code. This call never returns. */ +ERTS_NO_RETPOLINE void process_main(void) { static int init_done = 0; |