[PATCH 5.15 31/78] objtool: skip non-text sections when adding return-thunk sites

Greg Kroah-Hartman
2022-07-12T19:01:26Z

From: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

The .discard.text section is added in order to reserve BRK, with a
temporary function just so it can give it a size. This adds a relocation to
the return thunk, which objtool will add to the .return_sites section.
Linking will then fail as there are references to the .discard.text
section.

Do not add instructions from non-text sections to the list of return thunk
calls, avoiding the reference to .discard.text.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/objtool/check.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1153,7 +1153,9 @@ static void add_return_call(struct objto
insn->type = INSN_RETURN;
insn->retpoline_safe = true;

- list_add_tail(&insn->call_node, &file->return_thunk_list);
+ /* Skip the non-text sections, specially .discard ones */
+ if (insn->sec->text)
+ list_add_tail(&insn->call_node, &file->return_thunk_list);
}

/*