From: Julien Thierry <jthierry@redhat.com>
Date: Fri, 27 Mar 2020 15:28:41 +0000 (+0000)
Subject: objtool: Ignore empty alternatives
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7170cf47d16f1ba29eca07fd818870b7af0a93a5;p=linux.git

objtool: Ignore empty alternatives

The .alternatives section can contain entries with no original
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>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 5b67d6150a0b1..efb9640135527 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -905,6 +905,12 @@ 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)