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 <arjan@linux.intel.com>
 7 */
 8#define pr_fmt(fmt) "rodata_test: " fmt
 9
10#include <linux/uaccess.h>
11#include <asm/sections.h>
12
13static const int rodata_test_data = 0xC3;
14
15void rodata_test(void)
16{
17	unsigned long start, end;
18	int zero = 0;
19
20	/* test 1: read the value */
21	/* If this test fails, some previous testrun has clobbered the state */
22	if (!rodata_test_data) {
23		pr_err("test 1 fails (start data)\n");
24		return;
25	}
26
27	/* test 2: write to the variable; this should fault */
28	if (!probe_kernel_write((void *)&rodata_test_data,
29				(void *)&zero, sizeof(zero))) {
30		pr_err("test data was not read only\n");
31		return;
32	}
33
34	/* test 3: check the value hasn't changed */
35	if (rodata_test_data == zero) {
36		pr_err("test data was changed\n");
37		return;
38	}
39
40	/* test 4: check if the rodata section is PAGE_SIZE aligned */
41	start = (unsigned long)__start_rodata;
42	end = (unsigned long)__end_rodata;
43	if (start & (PAGE_SIZE - 1)) {
44		pr_err("start of .rodata is not page size aligned\n");
45		return;
46	}
47	if (end & (PAGE_SIZE - 1)) {
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}