On Tue, Apr 28, 2020 at 10:49:09AM -0500, Josh Poimboeuf wrote:
> On Tue, Apr 28, 2020 at 05:25:52PM +0200, Peter Zijlstra wrote:
> > On Tue, Apr 28, 2020 at 09:31:57AM -0500, Josh Poimboeuf wrote:
> > > That's quite the monstrosity, and I still don't see the point. I
> > > thought we decided to just disallow CFI changes in alternatives anyway?
> > > That can be done much simpler.
> >
> > Something like so then ?
> >
> > ---
> > diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> > index 8443ec690051..d14d83e6edb0 100644
> > --- a/tools/objtool/check.c
> > +++ b/tools/objtool/check.c
> > @@ -940,6 +940,7 @@ static int handle_group_alt(struct objtool_file *file,
> >
> > last_new_insn = insn;
> >
> > + insn->alt_group = true;
> > insn->ignore = orig_insn->ignore_alts;
> > insn->func = orig_insn->func;
> >
> > @@ -2242,6 +2243,11 @@ static int handle_insn_ops(struct instruction *insn,
> > struct insn_state *state)
> > list_for_each_entry(op, &insn->stack_ops, list) {
> > int res;
> >
> > + if (insn->alt_group) {
> > + WARN_FUNC("alternative has CFI", insn->sec,
> > insn->offset);
> > + return 1;
> > + }
> > +
>
> ACK (separate patch)
BTW, since most people don't know what CFI is, how about something like
"unsupported stack change in alternatives code"
--
Josh
