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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * rodata_test.c: functional test for mark_rodata_ro function
4 *
5 * (C) Copyright 2008 Intel Corporation
6 * Author: Arjan van de Ven <[email protected]>
7 */
8#define pr_fmt(fmt) "rodata_test: " fmt
9
10#include <linux/rodata_test.h>
11#include <linux/uaccess.h>
12#include <linux/mm.h>
13#include <asm/sections.h>
14
15#define TEST_VALUE 0xC3
16static const int rodata_test_data = TEST_VALUE;
17
18void rodata_test(void)
19{
20 int zero = 0;
21
22 /* test 1: read the value */
23 /* If this test fails, some previous testrun has clobbered the state */
24 if (unlikely(READ_ONCE(rodata_test_data) != TEST_VALUE)) {
25 pr_err("test 1 fails (start data)\n");
26 return;
27 }
28
29 /* test 2: write to the variable; this should fault */
30 if (!copy_to_kernel_nofault((void *)&rodata_test_data,
31 (void *)&zero, sizeof(zero))) {
32 pr_err("test data was not read only\n");
33 return;
34 }
35
36 /* test 3: check the value hasn't changed */
37 if (unlikely(READ_ONCE(rodata_test_data) != TEST_VALUE)) {
38 pr_err("test data was changed\n");
39 return;
40 }
41
42 /* test 4: check if the rodata section is PAGE_SIZE aligned */
43 if (!PAGE_ALIGNED(__start_rodata)) {
44 pr_err("start of .rodata is not page size aligned\n");
45 return;
46 }
47 if (!PAGE_ALIGNED(__end_rodata)) {
48 pr_err("end of .rodata is not page size aligned\n");
49 return;
50 }
51
52 pr_info("all tests were successful\n");
53}