objtool: Ignore unreachable fake jumps

It is possible for alternative code to unconditionally jump out of the
alternative region. In such a case, if a fake jump is added at the end
of the alternative instructions, the fake jump will never be reached.
Since the fake jump is just a mean to make sure code validation does not
go beyond the set of alternatives, reaching it is not a requirement.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index fd2edab8e6728398b3f7db77e74ebee8d4e38c32..cd7c6698d31692bf0b103e4ba9859366e5fdb610 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2648,6 +2648,9 @@ static bool ignore_unreachable_insn(struct instruction *insn)
            !strcmp(insn->sec->name, ".altinstr_aux"))
                return true;
 
+       if (insn->type == INSN_JUMP_UNCONDITIONAL && insn->offset == FAKE_JUMP_OFFSET)
+               return true;
+
        if (!insn->func)
                return false;