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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 <linux/module.h>
13#include <asm/cacheflush.h>
14#include <asm/sections.h>
15#include <asm/asm.h>
16
17int rodata_test(void)
18{
19 unsigned long result;
20 unsigned long start, end;
21
22 /* test 1: read the value */
23 /* If this test fails, some previous testrun has clobbered the state */
24 if (!rodata_test_data) {
25 printk(KERN_ERR "rodata_test: test 1 fails (start data)\n");
26 return -ENODEV;
27 }
28
29 /* test 2: write to the variable; this should fault */
30 /*
31 * If this test fails, we managed to overwrite the data
32 *
33 * This is written in assembly to be able to catch the
34 * exception that is supposed to happen in the correct
35 * case
36 */
37
38 result = 1;
39 asm volatile(
40 "0: mov %[zero],(%[rodata_test])\n"
41 " mov %[zero], %[rslt]\n"
42 "1:\n"
43 ".section .fixup,\"ax\"\n"
44 "2: jmp 1b\n"
45 ".previous\n"
46 _ASM_EXTABLE(0b,2b)
47 : [rslt] "=r" (result)
48 : [rodata_test] "r" (&rodata_test_data), [zero] "r" (0UL)
49 );
50
51
52 if (!result) {
53 printk(KERN_ERR "rodata_test: test data was not read only\n");
54 return -ENODEV;
55 }
56
57 /* test 3: check the value hasn't changed */
58 /* If this test fails, we managed to overwrite the data */
59 if (!rodata_test_data) {
60 printk(KERN_ERR "rodata_test: Test 3 failes (end data)\n");
61 return -ENODEV;
62 }
63 /* test 4: check if the rodata section is 4Kb aligned */
64 start = (unsigned long)__start_rodata;
65 end = (unsigned long)__end_rodata;
66 if (start & (PAGE_SIZE - 1)) {
67 printk(KERN_ERR "rodata_test: .rodata is not 4k aligned\n");
68 return -ENODEV;
69 }
70 if (end & (PAGE_SIZE - 1)) {
71 printk(KERN_ERR "rodata_test: .rodata end is not 4k aligned\n");
72 return -ENODEV;
73 }
74
75 return 0;
76}
77
78MODULE_LICENSE("GPL");
79MODULE_DESCRIPTION("Testcase for the DEBUG_RODATA infrastructure");
80MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
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 <linux/module.h>
13#include <asm/cacheflush.h>
14#include <asm/sections.h>
15#include <asm/asm.h>
16
17int rodata_test(void)
18{
19 unsigned long result;
20 unsigned long start, end;
21
22 /* test 1: read the value */
23 /* If this test fails, some previous testrun has clobbered the state */
24 if (!rodata_test_data) {
25 printk(KERN_ERR "rodata_test: test 1 fails (start data)\n");
26 return -ENODEV;
27 }
28
29 /* test 2: write to the variable; this should fault */
30 /*
31 * If this test fails, we managed to overwrite the data
32 *
33 * This is written in assembly to be able to catch the
34 * exception that is supposed to happen in the correct
35 * case
36 */
37
38 result = 1;
39 asm volatile(
40 "0: mov %[zero],(%[rodata_test])\n"
41 " mov %[zero], %[rslt]\n"
42 "1:\n"
43 ".section .fixup,\"ax\"\n"
44 "2: jmp 1b\n"
45 ".previous\n"
46 _ASM_EXTABLE(0b,2b)
47 : [rslt] "=r" (result)
48 : [rodata_test] "r" (&rodata_test_data), [zero] "r" (0UL)
49 );
50
51
52 if (!result) {
53 printk(KERN_ERR "rodata_test: test data was not read only\n");
54 return -ENODEV;
55 }
56
57 /* test 3: check the value hasn't changed */
58 /* If this test fails, we managed to overwrite the data */
59 if (!rodata_test_data) {
60 printk(KERN_ERR "rodata_test: Test 3 fails (end data)\n");
61 return -ENODEV;
62 }
63 /* test 4: check if the rodata section is 4Kb aligned */
64 start = (unsigned long)__start_rodata;
65 end = (unsigned long)__end_rodata;
66 if (start & (PAGE_SIZE - 1)) {
67 printk(KERN_ERR "rodata_test: .rodata is not 4k aligned\n");
68 return -ENODEV;
69 }
70 if (end & (PAGE_SIZE - 1)) {
71 printk(KERN_ERR "rodata_test: .rodata end is not 4k aligned\n");
72 return -ENODEV;
73 }
74
75 return 0;
76}
77
78MODULE_LICENSE("GPL");
79MODULE_DESCRIPTION("Testcase for marking rodata as read-only");
80MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");