[PATCH v2 20/58] objtool/klp: Add test for rejecting module-owned static branch keys

From: Puranjay Mohan <puranjay@kernel.org>

A static branch key belonging to a module cannot be reached with a klp
relocation: the patch may be applied after that module's static branch init
has run, which corrupts the code.  Emitting one anyway produces a module
which loads and then BUG()s the first time the key changes state, so klp
diff has to refuse it.

The fixture differs from the accepted case only in the module name recorded
in .modinfo.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Assisted-by: Claude:claude-opus-5
Signed-off-by: Song Liu <song@kernel.org>
---
 .../generic/test-jump-label-module-key.sh     | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100755 tools/objtool/tests/generic/test-jump-label-module-key.sh

diff --git a/tools/objtool/tests/generic/test-jump-label-module-key.sh b/tools/objtool/tests/generic/test-jump-label-module-key.sh
new file mode 100755
index 000000000000..7c3f82cdd3c1
--- /dev/null
+++ b/tools/objtool/tests/generic/test-jump-label-module-key.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# A static branch key owned by a module cannot be reached with a klp
+# relocation and must be rejected.
+
+. "$(dirname "$0")/../lib.sh"
+
+setup
+build_pair jump_label.c -DMODNAME='"klp_testmod"'
+
+has_input_section orig.o __jump_table ||
+	probe_skip "fixture produced no __jump_table on this arch"
+
+run_diff 255
+
+diff_log | grep -q 'unsupported static branch key klp_test_key' ||
+	fail "expected rejection, got: $(diff_log | tail -1)"
+[ -e "$workdir/out.o" ] &&
+	fail "output object produced for a rejected input"
+
+pass "module-owned static branch key rejected"

-- 
2.53.0-Meta