From 3c68a92d17add767109441f4040391b9e8a14a98 Mon Sep 17 00:00:00 2001 From: Sami Tolvanen Date: Thu, 8 Sep 2022 14:54:59 -0700 Subject: objtool: Disable CFI warnings The __cfi_ preambles contain a mov instruction that embeds the KCFI type identifier in the following format: ; type preamble __cfi_function: mov , %eax function: ... While the preamble symbols are STT_FUNC and contain valid instructions, they are never executed and always fall through. Skip the warning for them. .kcfi_traps sections point to CFI traps in text sections. Also skip the warning about them referencing !ENDBR instructions. Signed-off-by: Sami Tolvanen Reviewed-by: Kees Cook Tested-by: Kees Cook Tested-by: Nathan Chancellor Acked-by: Josh Poimboeuf Acked-by: Peter Zijlstra (Intel) Tested-by: Peter Zijlstra (Intel) Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220908215504.3686827-18-samitolvanen@google.com --- tools/objtool/check.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'tools/objtool') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index e55fdf952a3a..48e18737a2d1 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3316,6 +3316,10 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, next_insn = next_insn_to_validate(file, insn); if (func && insn->func && func != insn->func->pfunc) { + /* Ignore KCFI type preambles, which always fall through */ + if (!strncmp(func->name, "__cfi_", 6)) + return 0; + WARN("%s() falls through to next function %s()", func->name, insn->func->name); return 1; @@ -4113,7 +4117,8 @@ static int validate_ibt(struct objtool_file *file) !strcmp(sec->name, "__bug_table") || !strcmp(sec->name, "__ex_table") || !strcmp(sec->name, "__jump_table") || - !strcmp(sec->name, "__mcount_loc")) + !strcmp(sec->name, "__mcount_loc") || + !strcmp(sec->name, ".kcfi_traps")) continue; list_for_each_entry(reloc, &sec->reloc->reloc_list, list) -- cgit v1.2.3