[tip: objtool/core] objtool/klp: Add test for static local correlation

[tip-bot2 for Puranjay Mohan]

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     1267e8ac29f0023ec826838f02c0703a73c42d8e
Gitweb:        https://git.kernel.org/tip/1267e8ac29f0023ec826838f02c0703a73c42d8e
Author:        Puranjay Mohan <puranjay@xxxxxxxxxx>
AuthorDate:    Wed, 16 Sep 2026 11:43:08 -07:00
Committer:     Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
CommitterDate: Wed, 16 Sep 2026 17:13:27 -07:00

objtool/klp: Add test for static local correlation

A static local must be correlated with its original rather than duplicated.
The replacement has to reach the existing variable through a klp
relocation; a fresh definition would discard whatever state the running
kernel accumulated.

Signed-off-by: Puranjay Mohan <puranjay@xxxxxxxxxx>
Assisted-by: Claude:claude-opus-5
Signed-off-by: Song Liu <song@xxxxxxxxxx>
Link: https://patch.msgid.link/20260916184351.2720310-16-song@xxxxxxxxxx
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
 tools/objtool/tests/generic/fixtures/static_local.c | 17 +++++++++-
 tools/objtool/tests/generic/test-static-local.sh    | 24 ++++++++++++-
 2 files changed, 41 insertions(+)
 create mode 100644 tools/objtool/tests/generic/fixtures/static_local.c
 create mode 100755 tools/objtool/tests/generic/test-static-local.sh

diff --git a/tools/objtool/tests/generic/fixtures/static_local.c b/tools/objtool/tests/generic/fixtures/static_local.c
new file mode 100644
index 0000000..f2f025d
--- /dev/null
+++ b/tools/objtool/tests/generic/fixtures/static_local.c
@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Static local in a patched function. */
+
+static const char __modinfo[]
+	__attribute__((section(".modinfo"), used, aligned(1))) = "\0name=vmlinux";
+
+int target(int x)
+{
+	static int counter;
+
+	counter += 1;
+#ifdef PATCHED
+	return x + counter + 1;
+#else
+	return x + counter;
+#endif
+}
diff --git a/tools/objtool/tests/generic/test-static-local.sh b/tools/objtool/tests/generic/test-static-local.sh
new file mode 100755
index 0000000..d57efa6
--- /dev/null
+++ b/tools/objtool/tests/generic/test-static-local.sh
@@ -0,0 +1,24 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# A static local must be correlated with the original, not duplicated: a second
+# copy would discard the state the running kernel accumulated.
+
+. "$(dirname "$0")/../lib.sh"
+
+setup
+build_pair static_local.c
+
+in_symbols orig.o | grep -q 'counter' ||
+	probe_skip "compiler emitted no distinct static local symbol"
+
+run_diff
+assert_patched target
+
+out_symbols | grep -q '\.klp\.sym\..*\.counter' ||
+	fail "static local not referenced through a klp relocation"
+
+out_symbols | grep 'counter' | grep -qvE 'UND|\.klp\.(sym|tombstone)' &&
+	fail "static local was given a fresh definition"
+
+pass "static local correlated rather than duplicated"