longest_symbol_kunit.c

 1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Test the longest symbol length. Execute with:
 4 *  ./tools/testing/kunit/kunit.py run longest-symbol
 5 *  --arch=x86_64 --kconfig_add CONFIG_KPROBES=y --kconfig_add CONFIG_MODULES=y
 6 *  --kconfig_add CONFIG_CPU_MITIGATIONS=n --kconfig_add CONFIG_GCOV_KERNEL=n
 7 */
 8
 9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include <kunit/test.h>
12#include <linux/stringify.h>
13#include <linux/kprobes.h>
14#include <linux/kallsyms.h>
15
16#define DI(name) s##name##name
17#define DDI(name) DI(n##name##name)
18#define DDDI(name) DDI(n##name##name)
19#define DDDDI(name) DDDI(n##name##name)
20#define DDDDDI(name) DDDDI(n##name##name)
21
22/*Generate a symbol whose name length is 511 */
23#define LONGEST_SYM_NAME  DDDDDI(g1h2i3j4k5l6m7n)
24
25#define RETURN_LONGEST_SYM 0xAAAAA
26
27noinline int LONGEST_SYM_NAME(void);
28noinline int LONGEST_SYM_NAME(void)
29{
30	return RETURN_LONGEST_SYM;
31}
32
33_Static_assert(sizeof(__stringify(LONGEST_SYM_NAME)) == KSYM_NAME_LEN,
34"Incorrect symbol length found. Expected KSYM_NAME_LEN: "
35__stringify(KSYM_NAME_LEN) ", but found: "
36__stringify(sizeof(LONGEST_SYM_NAME)));
37
38static void test_longest_symbol(struct kunit *test)
39{
40	KUNIT_EXPECT_EQ(test, RETURN_LONGEST_SYM, LONGEST_SYM_NAME());
41};
42
43static void test_longest_symbol_kallsyms(struct kunit *test)
44{
45	unsigned long (*kallsyms_lookup_name)(const char *name);
46	static int (*longest_sym)(void);
47
48	struct kprobe kp = {
49		.symbol_name = "kallsyms_lookup_name",
50	};
51
52	if (register_kprobe(&kp) < 0) {
53		pr_info("%s: kprobe not registered", __func__);
54		KUNIT_FAIL(test, "test_longest_symbol kallsyms: kprobe not registered\n");
55		return;
56	}
57
58	kunit_warn(test, "test_longest_symbol kallsyms: kprobe registered\n");
59	kallsyms_lookup_name = (unsigned long (*)(const char *name))kp.addr;
60	unregister_kprobe(&kp);
61
62	longest_sym =
63		(void *) kallsyms_lookup_name(__stringify(LONGEST_SYM_NAME));
64	KUNIT_EXPECT_EQ(test, RETURN_LONGEST_SYM, longest_sym());
65};
66
67static struct kunit_case longest_symbol_test_cases[] = {
68	KUNIT_CASE(test_longest_symbol),
69	KUNIT_CASE(test_longest_symbol_kallsyms),
70	{}
71};
72
73static struct kunit_suite longest_symbol_test_suite = {
74	.name = "longest-symbol",
75	.test_cases = longest_symbol_test_cases,
76};
77kunit_test_suite(longest_symbol_test_suite);
78
79MODULE_LICENSE("GPL");
80MODULE_DESCRIPTION("Test the longest symbol length");
81MODULE_AUTHOR("Sergio González Collado");