selftests/ftrace: Add new test case which checks non unique symbol

If name_show() is non unique, this test will try to install a kprobe on this
function which should fail returning EADDRNOTAVAIL.
On kernel where name_show() is not unique, this test is skipped.

Link: https://lore.kernel.org/all/[email protected]/

Cc: [email protected]
Signed-off-by: Francis Laniel <[email protected]>
Acked-by: Masami Hiramatsu (Google) <[email protected]>
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>

Author: eiffel-fl

tools/testing/selftests/ftrace/test.d/kprobe/kprobe_non_uniq_symbol.tc

@@ -0,0 +1,13 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Test failure of registering kprobe on non unique symbol
+# requires: kprobe_events
+
+SYMBOL='name_show'
+
+# We skip this test on kernel where SYMBOL is unique or does not exist.
+if [ "$(grep -c -E "[[:alnum:]]+ t ${SYMBOL}" /proc/kallsyms)" -le '1' ]; then
+	exit_unsupported
+fi
+
+! echo "p:test_non_unique ${SYMBOL}" > kprobe_events