diff options
Diffstat (limited to 'tools/objtool/special.c')
| -rw-r--r-- | tools/objtool/special.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/tools/objtool/special.c b/tools/objtool/special.c index 50af4e1274b3..4e50563d87c6 100644 --- a/tools/objtool/special.c +++ b/tools/objtool/special.c @@ -23,6 +23,7 @@ #include <stdlib.h> #include <string.h> +#include "builtin.h" #include "special.h" #include "warn.h" @@ -42,6 +43,7 @@ #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 +112,22 @@ 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); |