1/*
 2 * test_rodata.c: functional test for mark_rodata_ro function
 3 *
 4 * (C) Copyright 2008 Intel Corporation
 5 * Author: Arjan van de Ven <arjan@linux.intel.com>
 6 *
 7 * This program is free software; you can redistribute it and/or
 8 * modify it under the terms of the GNU General Public License
 9 * as published by the Free Software Foundation; version 2
10 * of the License.
11 */
12#include <asm/cacheflush.h>
13#include <asm/sections.h>
14#include <asm/asm.h>
15
16int rodata_test(void)
17{
18	unsigned long result;
19	unsigned long start, end;
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		printk(KERN_ERR "rodata_test: test 1 fails (start data)\n");
25		return -ENODEV;
26	}
27
28	/* test 2: write to the variable; this should fault */
29	/*
30	 * If this test fails, we managed to overwrite the data
31	 *
32	 * This is written in assembly to be able to catch the
33	 * exception that is supposed to happen in the correct
34	 * case
35	 */
36
37	result = 1;
38	asm volatile(
39		"0:	mov %[zero],(%[rodata_test])\n"
40		"	mov %[zero], %[rslt]\n"
41		"1:\n"
42		".section .fixup,\"ax\"\n"
43		"2:	jmp 1b\n"
44		".previous\n"
45		_ASM_EXTABLE(0b,2b)
46		: [rslt] "=r" (result)
47		: [rodata_test] "r" (&rodata_test_data), [zero] "r" (0UL)
48	);
49
50
51	if (!result) {
52		printk(KERN_ERR "rodata_test: test data was not read only\n");
53		return -ENODEV;
54	}
55
56	/* test 3: check the value hasn't changed */
57	/* If this test fails, we managed to overwrite the data */
58	if (!rodata_test_data) {
59		printk(KERN_ERR "rodata_test: Test 3 fails (end data)\n");
60		return -ENODEV;
61	}
62	/* test 4: check if the rodata section is 4Kb aligned */
63	start = (unsigned long)__start_rodata;
64	end = (unsigned long)__end_rodata;
65	if (start & (PAGE_SIZE - 1)) {
66		printk(KERN_ERR "rodata_test: .rodata is not 4k aligned\n");
67		return -ENODEV;
68	}
69	if (end & (PAGE_SIZE - 1)) {
70		printk(KERN_ERR "rodata_test: .rodata end is not 4k aligned\n");
71		return -ENODEV;
72	}
73
74	return 0;
75}