Messages in this thread | | | Date | Wed, 1 Apr 2020 14:53:42 +0200 (CEST) | From | Miroslav Benes <> | Subject | Re: [PATCH v2 04/10] objtool: check: Ignore empty alternative groups |
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On Fri, 27 Mar 2020, Julien Thierry wrote:
> Atlernative section can contain entries for alternatives with no > instructions. Objtool will currently crash when handling such an entry. > > Just skip that entry, but still give a warning to discourage useless > entries. > > Signed-off-by: Julien Thierry <jthierry@redhat.com> > --- > tools/objtool/check.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/tools/objtool/check.c b/tools/objtool/check.c > index 74353b2c39ce..5c03460f1f07 100644 > --- a/tools/objtool/check.c > +++ b/tools/objtool/check.c > @@ -904,6 +904,12 @@ static int add_special_section_alts(struct objtool_file *file) > } > > if (special_alt->group) { > + if (!special_alt->orig_len) { > + WARN_FUNC("empty alternative entry", > + orig_insn->sec, orig_insn->offset); > + continue; > + } > + > ret = handle_group_alt(file, special_alt, orig_insn, > &new_insn); > if (ret)
Probably the first time I am looking at alternatives handling in objtool, so I must be missing something, but is this even possible now? I mean get_alt_entry() in special.c sets alt->orig_len when alt->group is true (which means .alternatives section) to something which cannot be zero.
Is this a preparatory patch for arm64, where this could happen? If yes, it would be better to mention it in the changelog.
Miroslav
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