diff options
Diffstat (limited to 'tools/objtool/arch/x86')
| -rw-r--r-- | tools/objtool/arch/x86/Build | 1 | ||||
| -rw-r--r-- | tools/objtool/arch/x86/special.c | 37 |
2 files changed, 38 insertions, 0 deletions
diff --git a/tools/objtool/arch/x86/Build b/tools/objtool/arch/x86/Build index 7c5004008e97..9f7869b5c5e0 100644 --- a/tools/objtool/arch/x86/Build +++ b/tools/objtool/arch/x86/Build @@ -1,3 +1,4 @@ +objtool-y += special.o objtool-y += decode.o inat_tables_script = ../arch/x86/tools/gen-insn-attr-x86.awk diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c new file mode 100644 index 000000000000..823561e4015c --- /dev/null +++ b/tools/objtool/arch/x86/special.c @@ -0,0 +1,37 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#include "../../special.h" +#include "../../builtin.h" + +#define X86_FEATURE_POPCNT (4 * 32 + 23) +#define X86_FEATURE_SMAP (9 * 32 + 20) + +void arch_handle_alternative(unsigned short feature, struct special_alt *alt) +{ + switch (feature) { + case X86_FEATURE_SMAP: + /* + * 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 (uaccess) + alt->skip_orig = true; + else + alt->skip_alt = true; + break; + case X86_FEATURE_POPCNT: + /* + * It has been requested that we don't validate the !POPCNT + * feature path which is a "very very small percentage of + * machines". + */ + alt->skip_orig = true; + break; + default: + break; + } +} |