1// SPDX-License-Identifier: GPL-2.0-only
2#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
3
4#include <linux/kernel.h>
5#include <linux/module.h>
6#include <linux/list.h>
7#include <linux/random.h>
8#include <linux/string.h>
9#include <linux/bitops.h>
10#include <linux/slab.h>
11#include <linux/mtd/nand_ecc.h>
12
13#include "mtd_test.h"
14
15/*
16 * Test the implementation for software ECC
17 *
18 * No actual MTD device is needed, So we don't need to warry about losing
19 * important data by human error.
20 *
21 * This covers possible patterns of corruption which can be reliably corrected
22 * or detected.
23 */
24
25#if IS_ENABLED(CONFIG_MTD_RAW_NAND)
26
27struct nand_ecc_test {
28	const char *name;
29	void (*prepare)(void *, void *, void *, void *, const size_t);
30	int (*verify)(void *, void *, void *, const size_t);
31};
32
33/*
34 * The reason for this __change_bit_le() instead of __change_bit() is to inject
35 * bit error properly within the region which is not a multiple of
36 * sizeof(unsigned long) on big-endian systems
37 */
38#ifdef __LITTLE_ENDIAN
39#define __change_bit_le(nr, addr) __change_bit(nr, addr)
40#elif defined(__BIG_ENDIAN)
41#define __change_bit_le(nr, addr) \
42		__change_bit((nr) ^ ((BITS_PER_LONG - 1) & ~0x7), addr)
43#else
44#error "Unknown byte order"
45#endif
46
47static void single_bit_error_data(void *error_data, void *correct_data,
48				size_t size)
49{
50	unsigned int offset = prandom_u32() % (size * BITS_PER_BYTE);
51
52	memcpy(error_data, correct_data, size);
53	__change_bit_le(offset, error_data);
54}
55
56static void double_bit_error_data(void *error_data, void *correct_data,
57				size_t size)
58{
59	unsigned int offset[2];
60
61	offset[0] = prandom_u32() % (size * BITS_PER_BYTE);
62	do {
63		offset[1] = prandom_u32() % (size * BITS_PER_BYTE);
64	} while (offset[0] == offset[1]);
65
66	memcpy(error_data, correct_data, size);
67
68	__change_bit_le(offset[0], error_data);
69	__change_bit_le(offset[1], error_data);
70}
71
72static unsigned int random_ecc_bit(size_t size)
73{
74	unsigned int offset = prandom_u32() % (3 * BITS_PER_BYTE);
75
76	if (size == 256) {
77		/*
78		 * Don't inject a bit error into the insignificant bits (16th
79		 * and 17th bit) in ECC code for 256 byte data block
80		 */
81		while (offset == 16 || offset == 17)
82			offset = prandom_u32() % (3 * BITS_PER_BYTE);
83	}
84
85	return offset;
86}
87
88static void single_bit_error_ecc(void *error_ecc, void *correct_ecc,
89				size_t size)
90{
91	unsigned int offset = random_ecc_bit(size);
92
93	memcpy(error_ecc, correct_ecc, 3);
94	__change_bit_le(offset, error_ecc);
95}
96
97static void double_bit_error_ecc(void *error_ecc, void *correct_ecc,
98				size_t size)
99{
100	unsigned int offset[2];
101
102	offset[0] = random_ecc_bit(size);
103	do {
104		offset[1] = random_ecc_bit(size);
105	} while (offset[0] == offset[1]);
106
107	memcpy(error_ecc, correct_ecc, 3);
108	__change_bit_le(offset[0], error_ecc);
109	__change_bit_le(offset[1], error_ecc);
110}
111
112static void no_bit_error(void *error_data, void *error_ecc,
113		void *correct_data, void *correct_ecc, const size_t size)
114{
115	memcpy(error_data, correct_data, size);
116	memcpy(error_ecc, correct_ecc, 3);
117}
118
119static int no_bit_error_verify(void *error_data, void *error_ecc,
120				void *correct_data, const size_t size)
121{
122	unsigned char calc_ecc[3];
123	int ret;
124
125	__nand_calculate_ecc(error_data, size, calc_ecc,
126			     IS_ENABLED(CONFIG_MTD_NAND_ECC_SW_HAMMING_SMC));
127	ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size,
128				  IS_ENABLED(CONFIG_MTD_NAND_ECC_SW_HAMMING_SMC));
129	if (ret == 0 && !memcmp(correct_data, error_data, size))
130		return 0;
131
132	return -EINVAL;
133}
134
135static void single_bit_error_in_data(void *error_data, void *error_ecc,
136		void *correct_data, void *correct_ecc, const size_t size)
137{
138	single_bit_error_data(error_data, correct_data, size);
139	memcpy(error_ecc, correct_ecc, 3);
140}
141
142static void single_bit_error_in_ecc(void *error_data, void *error_ecc,
143		void *correct_data, void *correct_ecc, const size_t size)
144{
145	memcpy(error_data, correct_data, size);
146	single_bit_error_ecc(error_ecc, correct_ecc, size);
147}
148
149static int single_bit_error_correct(void *error_data, void *error_ecc,
150				void *correct_data, const size_t size)
151{
152	unsigned char calc_ecc[3];
153	int ret;
154
155	__nand_calculate_ecc(error_data, size, calc_ecc,
156			     IS_ENABLED(CONFIG_MTD_NAND_ECC_SW_HAMMING_SMC));
157	ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size,
158				  IS_ENABLED(CONFIG_MTD_NAND_ECC_SW_HAMMING_SMC));
159	if (ret == 1 && !memcmp(correct_data, error_data, size))
160		return 0;
161
162	return -EINVAL;
163}
164
165static void double_bit_error_in_data(void *error_data, void *error_ecc,
166		void *correct_data, void *correct_ecc, const size_t size)
167{
168	double_bit_error_data(error_data, correct_data, size);
169	memcpy(error_ecc, correct_ecc, 3);
170}
171
172static void single_bit_error_in_data_and_ecc(void *error_data, void *error_ecc,
173		void *correct_data, void *correct_ecc, const size_t size)
174{
175	single_bit_error_data(error_data, correct_data, size);
176	single_bit_error_ecc(error_ecc, correct_ecc, size);
177}
178
179static void double_bit_error_in_ecc(void *error_data, void *error_ecc,
180		void *correct_data, void *correct_ecc, const size_t size)
181{
182	memcpy(error_data, correct_data, size);
183	double_bit_error_ecc(error_ecc, correct_ecc, size);
184}
185
186static int double_bit_error_detect(void *error_data, void *error_ecc,
187				void *correct_data, const size_t size)
188{
189	unsigned char calc_ecc[3];
190	int ret;
191
192	__nand_calculate_ecc(error_data, size, calc_ecc,
193			     IS_ENABLED(CONFIG_MTD_NAND_ECC_SW_HAMMING_SMC));
194	ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size,
195				  IS_ENABLED(CONFIG_MTD_NAND_ECC_SW_HAMMING_SMC));
196
197	return (ret == -EBADMSG) ? 0 : -EINVAL;
198}
199
200static const struct nand_ecc_test nand_ecc_test[] = {
201	{
202		.name = "no-bit-error",
203		.prepare = no_bit_error,
204		.verify = no_bit_error_verify,
205	},
206	{
207		.name = "single-bit-error-in-data-correct",
208		.prepare = single_bit_error_in_data,
209		.verify = single_bit_error_correct,
210	},
211	{
212		.name = "single-bit-error-in-ecc-correct",
213		.prepare = single_bit_error_in_ecc,
214		.verify = single_bit_error_correct,
215	},
216	{
217		.name = "double-bit-error-in-data-detect",
218		.prepare = double_bit_error_in_data,
219		.verify = double_bit_error_detect,
220	},
221	{
222		.name = "single-bit-error-in-data-and-ecc-detect",
223		.prepare = single_bit_error_in_data_and_ecc,
224		.verify = double_bit_error_detect,
225	},
226	{
227		.name = "double-bit-error-in-ecc-detect",
228		.prepare = double_bit_error_in_ecc,
229		.verify = double_bit_error_detect,
230	},
231};
232
233static void dump_data_ecc(void *error_data, void *error_ecc, void *correct_data,
234			void *correct_ecc, const size_t size)
235{
236	pr_info("hexdump of error data:\n");
237	print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 4,
238			error_data, size, false);
239	print_hex_dump(KERN_INFO, "hexdump of error ecc: ",
240			DUMP_PREFIX_NONE, 16, 1, error_ecc, 3, false);
241
242	pr_info("hexdump of correct data:\n");
243	print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 4,
244			correct_data, size, false);
245	print_hex_dump(KERN_INFO, "hexdump of correct ecc: ",
246			DUMP_PREFIX_NONE, 16, 1, correct_ecc, 3, false);
247}
248
249static int nand_ecc_test_run(const size_t size)
250{
251	int i;
252	int err = 0;
253	void *error_data;
254	void *error_ecc;
255	void *correct_data;
256	void *correct_ecc;
257
258	error_data = kmalloc(size, GFP_KERNEL);
259	error_ecc = kmalloc(3, GFP_KERNEL);
260	correct_data = kmalloc(size, GFP_KERNEL);
261	correct_ecc = kmalloc(3, GFP_KERNEL);
262
263	if (!error_data || !error_ecc || !correct_data || !correct_ecc) {
264		err = -ENOMEM;
265		goto error;
266	}
267
268	prandom_bytes(correct_data, size);
269	__nand_calculate_ecc(correct_data, size, correct_ecc,
270			     IS_ENABLED(CONFIG_MTD_NAND_ECC_SW_HAMMING_SMC));
271
272	for (i = 0; i < ARRAY_SIZE(nand_ecc_test); i++) {
273		nand_ecc_test[i].prepare(error_data, error_ecc,
274				correct_data, correct_ecc, size);
275		err = nand_ecc_test[i].verify(error_data, error_ecc,
276						correct_data, size);
277
278		if (err) {
279			pr_err("not ok - %s-%zd\n",
280				nand_ecc_test[i].name, size);
281			dump_data_ecc(error_data, error_ecc,
282				correct_data, correct_ecc, size);
283			break;
284		}
285		pr_info("ok - %s-%zd\n",
286			nand_ecc_test[i].name, size);
287
288		err = mtdtest_relax();
289		if (err)
290			break;
291	}
292error:
293	kfree(error_data);
294	kfree(error_ecc);
295	kfree(correct_data);
296	kfree(correct_ecc);
297
298	return err;
299}
300
301#else
302
303static int nand_ecc_test_run(const size_t size)
304{
305	return 0;
306}
307
308#endif
309
310static int __init ecc_test_init(void)
311{
312	int err;
313
314	err = nand_ecc_test_run(256);
315	if (err)
316		return err;
317
318	return nand_ecc_test_run(512);
319}
320
321static void __exit ecc_test_exit(void)
322{
323}
324
325module_init(ecc_test_init);
326module_exit(ecc_test_exit);
327
328MODULE_DESCRIPTION("NAND ECC function test module");
329MODULE_AUTHOR("Akinobu Mita");
330MODULE_LICENSE("GPL");
331