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/rodata_test.h>
11 #include <linux/uaccess.h>
12 #include <asm/sections.h>
13 
14 static const int rodata_test_data = 0xC3;
15 
rodata_test(void)16 void rodata_test(void)
17 {
18 	unsigned long start, end;
19 	int zero = 0;
20 
21 	/* test 1: read the value */
22 	/* If this test fails, some previous testrun has clobbered the state */
23 	if (!rodata_test_data) {
24 		pr_err("test 1 fails (start data)\n");
25 		return;
26 	}
27 
28 	/* test 2: write to the variable; this should fault */
29 	if (!copy_to_kernel_nofault((void *)&rodata_test_data,
30 				(void *)&zero, sizeof(zero))) {
31 		pr_err("test data was not read only\n");
32 		return;
33 	}
34 
35 	/* test 3: check the value hasn't changed */
36 	if (rodata_test_data == zero) {
37 		pr_err("test data was changed\n");
38 		return;
39 	}
40 
41 	/* test 4: check if the rodata section is PAGE_SIZE aligned */
42 	start = (unsigned long)__start_rodata;
43 	end = (unsigned long)__end_rodata;
44 	if (start & (PAGE_SIZE - 1)) {
45 		pr_err("start of .rodata is not page size aligned\n");
46 		return;
47 	}
48 	if (end & (PAGE_SIZE - 1)) {
49 		pr_err("end of .rodata is not page size aligned\n");
50 		return;
51 	}
52 
53 	pr_info("all tests were successful\n");
54 }
55