linux-kernel - [RFC v5 04/57] objtool: check: Ignore empty alternative groups

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Message-Id: <20200109160300.26150-5-jthierry@redhat.com>
Date:   Thu,  9 Jan 2020 16:02:07 +0000
From:   Julien Thierry <jthierry@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     jpoimboe@...hat.com, peterz@...radead.org, raphael.gault@....com,
        catalin.marinas@....com, will@...nel.org,
        Julien Thierry <jthierry@...hat.com>
Subject: [RFC v5 04/57] objtool: check: Ignore empty alternative groups

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@...hat.com>
---
 tools/objtool/check.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 5968e6f08891..27e5380e0e0b 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -866,6 +866,13 @@ static int add_special_section_alts(struct objtool_file *file)
 		}
 
 		if (special_alt->group) {
+			if (!special_alt->orig_len) {
+				WARN("empty alternative entry at %s+0x%lx",
+				     orig_insn->sec->name,
+				     orig_insn->offset);
+				continue;
+			}
+
 			ret = handle_group_alt(file, special_alt, orig_insn,
 					       &new_insn);
 			if (ret)
-- 
2.21.0