summaryrefslogtreecommitdiffstats
path: root/fs/pstore/ram_core.c
blob: f1848cdd6d34855f9d32986d7e8d0c407823a625 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 Google, Inc.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/memblock.h>
#include <linux/rslib.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <asm/page.h>

#include "ram_internal.h"

/**
 * struct persistent_ram_buffer - persistent circular RAM buffer
 *
 * @sig: Signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
 * @start: First valid byte in the buffer.
 * @size: Number of valid bytes in the buffer.
 * @data: The contents of the buffer.
 */
struct persistent_ram_buffer {
	uint32_t    sig;
	atomic_t    start;
	atomic_t    size;
	uint8_t     data[];
};

#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */

static inline size_t buffer_size(struct persistent_ram_zone *prz)
{
	return atomic_read(&prz->buffer->size);
}

static inline size_t buffer_start(struct persistent_ram_zone *prz)
{
	return atomic_read(&prz->buffer->start);
}

/* increase and wrap the start pointer, returning the old value */
static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
{
	int old;
	int new;
	unsigned long flags = 0;

	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
		raw_spin_lock_irqsave(&prz->buffer_lock, flags);

	old = atomic_read(&prz->buffer->start);
	new = old + a;
	while (unlikely(new >= prz->buffer_size))
		new -= prz->buffer_size;
	atomic_set(&prz->buffer->start, new);

	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
		raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);

	return old;
}

/* increase the size counter until it hits the max size */
static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
{
	size_t old;
	size_t new;
	unsigned long flags = 0;

	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
		raw_spin_lock_irqsave(&prz->buffer_lock, flags);

	old = atomic_read(&prz->buffer->size);
	if (old == prz->buffer_size)
		goto exit;

	new = old + a;
	if (new > prz->buffer_size)
		new = prz->buffer_size;
	atomic_set(&prz->buffer->size, new);

exit:
	if (!(prz->flags & PRZ_FLAG_NO_LOCK))
		raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
}

static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
	uint8_t *data, size_t len, uint8_t *ecc)
{
	int i;

	/* Initialize the parity buffer */
	memset(prz->ecc_info.par, 0,
	       prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));
	encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);
	for (i = 0; i < prz->ecc_info.ecc_size; i++)
		ecc[i] = prz->ecc_info.par[i];
}

static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
	void *data, size_t len, uint8_t *ecc)
{
	int i;

	for (i = 0; i < prz->ecc_info.ecc_size; i++)
		prz->ecc_info.par[i] = ecc[i];
	return decode_rs8(prz->rs_decoder, data, prz->ecc_info.par, len,
				NULL, 0, NULL, 0, NULL);
}

static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
	unsigned int start, unsigned int count)
{
	struct persistent_ram_buffer *buffer = prz->buffer;
	uint8_t *buffer_end = buffer->data + prz->buffer_size;
	uint8_t *block;
	uint8_t *par;
	int ecc_block_size = prz->ecc_info.block_size;
	int ecc_size = prz->ecc_info.ecc_size;
	int size = ecc_block_size;

	if (!ecc_size)
		return;

	block = buffer->data + (start & ~(ecc_block_size - 1));
	par = prz->par_buffer + (start / ecc_block_size) * ecc_size;

	do {
		if (block + ecc_block_size > buffer_end)
			size = buffer_end - block;
		persistent_ram_encode_rs8(prz, block, size, par);
		block += ecc_block_size;
		par += ecc_size;
	} while (block < buffer->data + start + count);
}

static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
{
	struct persistent_ram_buffer *buffer = prz->buffer;

	if (!prz->ecc_info.ecc_size)
		return;

	persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
				  prz->par_header);
}

static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
{
	struct persistent_ram_buffer *buffer = prz->buffer;
	uint8_t *block;
	uint8_t *par;

	if (!prz->ecc_info.ecc_size)
		return;

	block = buffer->data;
	par = prz->par_buffer;
	while (block < buffer->data + buffer_size(prz)) {
		int numerr;
		int size = prz->ecc_info.block_size;
		if (block + size > buffer->data + prz->buffer_size)
			size = buffer->data + prz->buffer_size - block;
		numerr = persistent_ram_decode_rs8(prz, block, size, par);
		if (numerr > 0) {
			pr_devel("error in block %p, %d\n", block, numerr);
			prz->corrected_bytes += numerr;
		} else if (numerr < 0) {
			pr_devel("uncorrectable error in block %p\n", block);
			prz->bad_blocks++;
		}
		block += prz->ecc_info.block_size;
		par += prz->ecc_info.ecc_size;
	}
}

static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
				   struct persistent_ram_ecc_info *ecc_info)
{
	int numerr;
	struct persistent_ram_buffer *buffer = prz->buffer;
	size_t ecc_blocks;
	size_t ecc_total;

	if (!ecc_info || !ecc_info->ecc_size)
		return 0;

	prz->ecc_info.block_size = ecc_info->block_size ?: 128;
	prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
	prz->ecc_info.symsize = ecc_info->symsize ?: 8;
	prz->ecc_info.poly = ecc_info->poly ?: 0x11d;

	ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
				  prz->ecc_info.block_size +
				  prz->ecc_info.ecc_size);
	ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
	if (ecc_total >= prz->buffer_size) {
		pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
		       __func__, prz->ecc_info.ecc_size,
		       ecc_total, prz->buffer_size);
		return -EINVAL;
	}

	prz->buffer_size -= ecc_total;
	prz->par_buffer = buffer->data + prz->buffer_size;
	prz->par_header = prz->par_buffer +
			  ecc_blocks * prz->ecc_info.ecc_size;

	/*
	 * first consecutive root is 0
	 * primitive element to generate roots = 1
	 */
	prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
				  0, 1, prz->ecc_info.ecc_size);
	if (prz->rs_decoder == NULL) {
		pr_info("init_rs failed\n");
		return -EINVAL;
	}

	/* allocate workspace instead of using stack VLA */
	prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,
					  sizeof(*prz->ecc_info.par),
					  GFP_KERNEL);
	if (!prz->ecc_info.par) {
		pr_err("cannot allocate ECC parity workspace\n");
		return -ENOMEM;
	}

	prz->corrected_bytes = 0;
	prz->bad_blocks = 0;

	numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
					   prz->par_header);
	if (numerr > 0) {
		pr_info("error in header, %d\n", numerr);
		prz->corrected_bytes += numerr;
	} else if (numerr < 0) {
		pr_info_ratelimited("uncorrectable error in header\n");
		prz->bad_blocks++;
	}

	return 0;
}

ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
	char *str, size_t len)
{
	ssize_t ret;

	if (!prz->ecc_info.ecc_size)
		return 0;

	if (prz->corrected_bytes || prz->bad_blocks)
		ret = snprintf(str, len, ""
			"\nECC: %d Corrected bytes, %d unrecoverable blocks\n",
			prz->corrected_bytes, prz->bad_blocks);
	else
		ret = snprintf(str, len, "\nECC: No errors detected\n");

	return ret;
}

static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
	const void *s, unsigned int start, unsigned int count)
{
	struct persistent_ram_buffer *buffer = prz->buffer;
	memcpy_toio(buffer->data + start, s, count);
	persistent_ram_update_ecc(prz, start, count);
}

static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
	const void __user *s, unsigned int start, unsigned int count)
{
	struct persistent_ram_buffer *buffer = prz->buffer;
	int ret = unlikely(copy_from_user(buffer->data + start, s, count)) ?
		-EFAULT : 0;
	persistent_ram_update_ecc(prz, start, count);
	return ret;
}

void persistent_ram_save_old(struct persistent_ram_zone *prz)
{
	struct persistent_ram_buffer *buffer = prz->buffer;
	size_t size = buffer_size(prz);
	size_t start = buffer_start(prz);

	if (!size)
		return;

	if (!prz->old_log) {
		persistent_ram_ecc_old(prz);
		prz->old_log = kvzalloc(size, GFP_KERNEL);
	}
	if (!prz->old_log) {
		pr_err("failed to allocate buffer\n");
		return;
	}

	prz->old_log_size = size;
	memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
	memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
}

int notrace persistent_ram_write(struct persistent_ram_zone *prz,
	const void *s, unsigned int count)
{
	int rem;
	int c = count;
	size_t start;

	if (unlikely(c > prz->buffer_size)) {
		s += c - prz->buffer_size;
		c = prz->buffer_size;
	}

	buffer_size_add(prz, c);

	start = buffer_start_add(prz, c);

	rem = prz->buffer_size - start;
	if (unlikely(rem < c)) {
		persistent_ram_update(prz, s, start, rem);
		s += rem;
		c -= rem;
		start = 0;
	}
	persistent_ram_update(prz, s, start, c);

	persistent_ram_update_header_ecc(prz);

	return count;
}

int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
	const void __user *s, unsigned int count)
{
	int rem, ret = 0, c = count;
	size_t start;

	if (unlikely(c > prz->buffer_size)) {
		s += c - prz->buffer_size;
		c = prz->buffer_size;
	}

	buffer_size_add(prz, c);

	start = buffer_start_add(prz, c);

	rem = prz->buffer_size - start;
	if (unlikely(rem < c)) {
		ret = persistent_ram_update_user(prz, s, start, rem);
		s += rem;
		c -= rem;
		start = 0;
	}
	if (likely(!ret))
		ret = persistent_ram_update_user(prz, s, start, c);

	persistent_ram_update_header_ecc(prz);

	return unlikely(ret) ? ret : count;
}

size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
{
	return prz->old_log_size;
}

void *persistent_ram_old(struct persistent_ram_zone *prz)
{
	return prz->old_log;
}

void persistent_ram_free_old(struct persistent_ram_zone *prz)
{
	kvfree(prz->old_log);
	prz->old_log = NULL;
	prz->old_log_size = 0;
}

void persistent_ram_zap(struct persistent_ram_zone *prz)
{
	atomic_set(&prz->buffer->start, 0);
	atomic_set(&prz->buffer->size, 0);
	persistent_ram_update_header_ecc(prz);
}

#define MEM_TYPE_WCOMBINE	0
#define MEM_TYPE_NONCACHED	1
#define MEM_TYPE_NORMAL		2

static void *persistent_ram_vmap(phys_addr_t start, size_t size,
		unsigned int memtype)
{
	struct page **pages;
	phys_addr_t page_start;
	unsigned int page_count;
	pgprot_t prot;
	unsigned int i;
	void *vaddr;

	page_start = start - offset_in_page(start);
	page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);

	switch (memtype) {
	case MEM_TYPE_NORMAL:
		prot = PAGE_KERNEL;
		break;
	case MEM_TYPE_NONCACHED:
		prot = pgprot_noncached(PAGE_KERNEL);
		break;
	case MEM_TYPE_WCOMBINE:
		prot = pgprot_writecombine(PAGE_KERNEL);
		break;
	default:
		pr_err("invalid mem_type=%d\n", memtype);
		return NULL;
	}

	pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
	if (!pages) {
		pr_err("%s: Failed to allocate array for %u pages\n",
		       __func__, page_count);
		return NULL;
	}

	for (i = 0; i < page_count; i++) {
		phys_addr_t addr = page_start + i * PAGE_SIZE;
		pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
	}
	/*
	 * VM_IOREMAP used here to bypass this region during vread()
	 * and kmap_atomic() (i.e. kcore) to avoid __va() failures.
	 */
	vaddr = vmap(pages, page_count, VM_MAP | VM_IOREMAP, prot);
	kfree(pages);

	/*
	 * Since vmap() uses page granularity, we must add the offset
	 * into the page here, to get the byte granularity address
	 * into the mapping to represent the actual "start" location.
	 */
	return vaddr + offset_in_page(start);
}

static void *persistent_ram_iomap(phys_addr_t start, size_t size,
		unsigned int memtype, char *label)
{
	void *va;

	if (!request_mem_region(start, size, label ?: "ramoops")) {
		pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
			label ?: "ramoops",
			(unsigned long long)size, (unsigned long long)start);
		return NULL;
	}

	if (memtype)
		va = ioremap(start, size);
	else
		va = ioremap_wc(start, size);

	/*
	 * Since request_mem_region() and ioremap() are byte-granularity
	 * there is no need handle anything special like we do when the
	 * vmap() case in persistent_ram_vmap() above.
	 */
	return va;
}

static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
		struct persistent_ram_zone *prz, int memtype)
{
	prz->paddr = start;
	prz->size = size;

	if (pfn_valid(start >> PAGE_SHIFT))
		prz->vaddr = persistent_ram_vmap(start, size, memtype);
	else
		prz->vaddr = persistent_ram_iomap(start, size, memtype,
						  prz->label);

	if (!prz->vaddr) {
		pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
			(unsigned long long)size, (unsigned long long)start);
		return -ENOMEM;
	}

	prz->buffer = prz->vaddr;
	prz->buffer_size = size - sizeof(struct persistent_ram_buffer);

	return 0;
}

static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
				    struct persistent_ram_ecc_info *ecc_info)
{
	int ret;
	bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);

	ret = persistent_ram_init_ecc(prz, ecc_info);
	if (ret) {
		pr_warn("ECC failed %s\n", prz->label);
		return ret;
	}

	sig ^= PERSISTENT_RAM_SIG;

	if (prz->buffer->sig == sig) {
		if (buffer_size(prz) == 0 && buffer_start(prz) == 0) {
			pr_debug("found existing empty buffer\n");
			return 0;
		}

		if (buffer_size(prz) > prz->buffer_size ||
		    buffer_start(prz) > buffer_size(prz)) {
			pr_info("found existing invalid buffer, size %zu, start %zu\n",
				buffer_size(prz), buffer_start(prz));
			zap = true;
		} else {
			pr_debug("found existing buffer, size %zu, start %zu\n",
				 buffer_size(prz), buffer_start(prz));
			persistent_ram_save_old(prz);
		}
	} else {
		pr_debug("no valid data in buffer (sig = 0x%08x)\n",
			 prz->buffer->sig);
		prz->buffer->sig = sig;
		zap = true;
	}

	/* Reset missing, invalid, or single-use memory area. */
	if (zap)
		persistent_ram_zap(prz);

	return 0;
}

void persistent_ram_free(struct persistent_ram_zone **_prz)
{
	struct persistent_ram_zone *prz;

	if (!_prz)
		return;

	prz = *_prz;
	if (!prz)
		return;

	if (prz->vaddr) {
		if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
			/* We must vunmap() at page-granularity. */
			vunmap(prz->vaddr - offset_in_page(prz->paddr));
		} else {
			iounmap(prz->vaddr);
			release_mem_region(prz->paddr, prz->size);
		}
		prz->vaddr = NULL;
	}
	if (prz->rs_decoder) {
		free_rs(prz->rs_decoder);
		prz->rs_decoder = NULL;
	}
	kfree(prz->ecc_info.par);
	prz->ecc_info.par = NULL;

	persistent_ram_free_old(prz);
	kfree(prz->label);
	kfree(prz);
	*_prz = NULL;
}

struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
			u32 sig, struct persistent_ram_ecc_info *ecc_info,
			unsigned int memtype, u32 flags, char *label)
{
	struct persistent_ram_zone *prz;
	int ret = -ENOMEM;

	prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
	if (!prz) {
		pr_err("failed to allocate persistent ram zone\n");
		goto err;
	}

	/* Initialize general buffer state. */
	raw_spin_lock_init(&prz->buffer_lock);
	prz->flags = flags;
	prz->label = kstrdup(label, GFP_KERNEL);
	if (!prz->label)
		goto err;

	ret = persistent_ram_buffer_map(start, size, prz, memtype);
	if (ret)
		goto err;

	ret = persistent_ram_post_init(prz, sig, ecc_info);
	if (ret)
		goto err;

	pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
		prz->label, prz->size, (unsigned long long)prz->paddr,
		sizeof(*prz->buffer), prz->buffer_size,
		prz->size - sizeof(*prz->buffer) - prz->buffer_size,
		prz->ecc_info.ecc_size, prz->ecc_info.block_size);

	return prz;
err:
	persistent_ram_free(&prz);
	return ERR_PTR(ret);
}