diff options
Diffstat (limited to 'tools/objtool/special.c')
| -rw-r--r-- | tools/objtool/special.c | 32 |
1 files changed, 19 insertions, 13 deletions
diff --git a/tools/objtool/special.c b/tools/objtool/special.c index 50af4e1274b3..fdbaa611146d 100644 --- a/tools/objtool/special.c +++ b/tools/objtool/special.c @@ -1,18 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0-or-later /* * Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com> - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License - * as published by the Free Software Foundation; either version 2 - * of the License, or (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, see <http://www.gnu.org/licenses/>. */ /* @@ -23,6 +11,7 @@ #include <stdlib.h> #include <string.h> +#include "builtin.h" #include "special.h" #include "warn.h" @@ -42,6 +31,7 @@ #define ALT_NEW_LEN_OFFSET 11 #define X86_FEATURE_POPCNT (4*32+23) +#define X86_FEATURE_SMAP (9*32+20) struct special_entry { const char *sec; @@ -110,6 +100,22 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry, */ if (feature == X86_FEATURE_POPCNT) alt->skip_orig = true; + + /* + * If UACCESS validation is enabled; force that alternative; + * otherwise force it the other way. + * + * What we want to avoid is having both the original and the + * alternative code flow at the same time, in that case we can + * find paths that see the STAC but take the NOP instead of + * CLAC and the other way around. + */ + if (feature == X86_FEATURE_SMAP) { + if (uaccess) + alt->skip_orig = true; + else + alt->skip_alt = true; + } } orig_rela = find_rela_by_dest(sec, offset + entry->orig); |