On Tue, Apr 28, 2020 at 06:44:44PM +0200, Peter Zijlstra wrote:
> > > @@ -2494,8 +2494,16 @@ static int validate_branch(struct objtool_file
> > > *file, struct symbol *func,
> > > }
> > > }
> > >
> > > - if (skip_orig)
> > > + if (skip_orig) {
> > > + struct instruction *prev_insn = insn;
> > > + sec_for_each_insn_continue(file, insn) {
> > > + if (!insn->alt_group)
> > > + break;
> > > + if (!insn->visited)
> > > + insn->cfi = prev_insn->cfi;
> > > + }
> > > return 0;
> > > + }
> >
> > NACK :-)
> >
> > What happens if you have two alternatives adjacent to each other (which
> > can definitely happen in this scenario)?
>
> Alexandre's alt_group would help:
>
> [email protected]
>
> Then we can do something like:
>
> static void fill_alternative(struct instruction *insn)
> {
> struct instruction *first_insn = insn;
> int alt_group = insn->alt_group;
>
> sec_for_each_insn_continue(file, insn) {
> if (insn->alt_group != alt_group)
> break;
> if (!insn->visited)
> insn->cfi = first_insn->cfi;
> }
> }
Ugh...
> > I still like my patch, at least the hack is done before the validate
> > code, so validate_branch() itself is simpler.
>
> But it doesn't handle the case where the alternatives themselves have
> unreachable holes in them, if that happens we'll generate spurious ORC
> entries for them.
Ah, I see what you mean.
I need to think about it...
--
Josh
