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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Google, Inc.
4 */
5
6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
7
8#include <linux/device.h>
9#include <linux/err.h>
10#include <linux/errno.h>
11#include <linux/init.h>
12#include <linux/io.h>
13#include <linux/kernel.h>
14#include <linux/list.h>
15#include <linux/memblock.h>
16#include <linux/pstore_ram.h>
17#include <linux/rslib.h>
18#include <linux/slab.h>
19#include <linux/uaccess.h>
20#include <linux/vmalloc.h>
21#include <asm/page.h>
22
23/**
24 * struct persistent_ram_buffer - persistent circular RAM buffer
25 *
26 * @sig:
27 * signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
28 * @start:
29 * offset into @data where the beginning of the stored bytes begin
30 * @size:
31 * number of valid bytes stored in @data
32 */
33struct persistent_ram_buffer {
34 uint32_t sig;
35 atomic_t start;
36 atomic_t size;
37 uint8_t data[];
38};
39
40#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
41
42static inline size_t buffer_size(struct persistent_ram_zone *prz)
43{
44 return atomic_read(&prz->buffer->size);
45}
46
47static inline size_t buffer_start(struct persistent_ram_zone *prz)
48{
49 return atomic_read(&prz->buffer->start);
50}
51
52/* increase and wrap the start pointer, returning the old value */
53static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
54{
55 int old;
56 int new;
57 unsigned long flags = 0;
58
59 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
60 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
61
62 old = atomic_read(&prz->buffer->start);
63 new = old + a;
64 while (unlikely(new >= prz->buffer_size))
65 new -= prz->buffer_size;
66 atomic_set(&prz->buffer->start, new);
67
68 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
69 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
70
71 return old;
72}
73
74/* increase the size counter until it hits the max size */
75static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
76{
77 size_t old;
78 size_t new;
79 unsigned long flags = 0;
80
81 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
82 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
83
84 old = atomic_read(&prz->buffer->size);
85 if (old == prz->buffer_size)
86 goto exit;
87
88 new = old + a;
89 if (new > prz->buffer_size)
90 new = prz->buffer_size;
91 atomic_set(&prz->buffer->size, new);
92
93exit:
94 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
95 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
96}
97
98static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
99 uint8_t *data, size_t len, uint8_t *ecc)
100{
101 int i;
102
103 /* Initialize the parity buffer */
104 memset(prz->ecc_info.par, 0,
105 prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));
106 encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);
107 for (i = 0; i < prz->ecc_info.ecc_size; i++)
108 ecc[i] = prz->ecc_info.par[i];
109}
110
111static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
112 void *data, size_t len, uint8_t *ecc)
113{
114 int i;
115
116 for (i = 0; i < prz->ecc_info.ecc_size; i++)
117 prz->ecc_info.par[i] = ecc[i];
118 return decode_rs8(prz->rs_decoder, data, prz->ecc_info.par, len,
119 NULL, 0, NULL, 0, NULL);
120}
121
122static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
123 unsigned int start, unsigned int count)
124{
125 struct persistent_ram_buffer *buffer = prz->buffer;
126 uint8_t *buffer_end = buffer->data + prz->buffer_size;
127 uint8_t *block;
128 uint8_t *par;
129 int ecc_block_size = prz->ecc_info.block_size;
130 int ecc_size = prz->ecc_info.ecc_size;
131 int size = ecc_block_size;
132
133 if (!ecc_size)
134 return;
135
136 block = buffer->data + (start & ~(ecc_block_size - 1));
137 par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
138
139 do {
140 if (block + ecc_block_size > buffer_end)
141 size = buffer_end - block;
142 persistent_ram_encode_rs8(prz, block, size, par);
143 block += ecc_block_size;
144 par += ecc_size;
145 } while (block < buffer->data + start + count);
146}
147
148static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
149{
150 struct persistent_ram_buffer *buffer = prz->buffer;
151
152 if (!prz->ecc_info.ecc_size)
153 return;
154
155 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
156 prz->par_header);
157}
158
159static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
160{
161 struct persistent_ram_buffer *buffer = prz->buffer;
162 uint8_t *block;
163 uint8_t *par;
164
165 if (!prz->ecc_info.ecc_size)
166 return;
167
168 block = buffer->data;
169 par = prz->par_buffer;
170 while (block < buffer->data + buffer_size(prz)) {
171 int numerr;
172 int size = prz->ecc_info.block_size;
173 if (block + size > buffer->data + prz->buffer_size)
174 size = buffer->data + prz->buffer_size - block;
175 numerr = persistent_ram_decode_rs8(prz, block, size, par);
176 if (numerr > 0) {
177 pr_devel("error in block %p, %d\n", block, numerr);
178 prz->corrected_bytes += numerr;
179 } else if (numerr < 0) {
180 pr_devel("uncorrectable error in block %p\n", block);
181 prz->bad_blocks++;
182 }
183 block += prz->ecc_info.block_size;
184 par += prz->ecc_info.ecc_size;
185 }
186}
187
188static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
189 struct persistent_ram_ecc_info *ecc_info)
190{
191 int numerr;
192 struct persistent_ram_buffer *buffer = prz->buffer;
193 int ecc_blocks;
194 size_t ecc_total;
195
196 if (!ecc_info || !ecc_info->ecc_size)
197 return 0;
198
199 prz->ecc_info.block_size = ecc_info->block_size ?: 128;
200 prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
201 prz->ecc_info.symsize = ecc_info->symsize ?: 8;
202 prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
203
204 ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
205 prz->ecc_info.block_size +
206 prz->ecc_info.ecc_size);
207 ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
208 if (ecc_total >= prz->buffer_size) {
209 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
210 __func__, prz->ecc_info.ecc_size,
211 ecc_total, prz->buffer_size);
212 return -EINVAL;
213 }
214
215 prz->buffer_size -= ecc_total;
216 prz->par_buffer = buffer->data + prz->buffer_size;
217 prz->par_header = prz->par_buffer +
218 ecc_blocks * prz->ecc_info.ecc_size;
219
220 /*
221 * first consecutive root is 0
222 * primitive element to generate roots = 1
223 */
224 prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
225 0, 1, prz->ecc_info.ecc_size);
226 if (prz->rs_decoder == NULL) {
227 pr_info("init_rs failed\n");
228 return -EINVAL;
229 }
230
231 /* allocate workspace instead of using stack VLA */
232 prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,
233 sizeof(*prz->ecc_info.par),
234 GFP_KERNEL);
235 if (!prz->ecc_info.par) {
236 pr_err("cannot allocate ECC parity workspace\n");
237 return -ENOMEM;
238 }
239
240 prz->corrected_bytes = 0;
241 prz->bad_blocks = 0;
242
243 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
244 prz->par_header);
245 if (numerr > 0) {
246 pr_info("error in header, %d\n", numerr);
247 prz->corrected_bytes += numerr;
248 } else if (numerr < 0) {
249 pr_info("uncorrectable error in header\n");
250 prz->bad_blocks++;
251 }
252
253 return 0;
254}
255
256ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
257 char *str, size_t len)
258{
259 ssize_t ret;
260
261 if (!prz->ecc_info.ecc_size)
262 return 0;
263
264 if (prz->corrected_bytes || prz->bad_blocks)
265 ret = snprintf(str, len, ""
266 "\n%d Corrected bytes, %d unrecoverable blocks\n",
267 prz->corrected_bytes, prz->bad_blocks);
268 else
269 ret = snprintf(str, len, "\nNo errors detected\n");
270
271 return ret;
272}
273
274static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
275 const void *s, unsigned int start, unsigned int count)
276{
277 struct persistent_ram_buffer *buffer = prz->buffer;
278 memcpy_toio(buffer->data + start, s, count);
279 persistent_ram_update_ecc(prz, start, count);
280}
281
282static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
283 const void __user *s, unsigned int start, unsigned int count)
284{
285 struct persistent_ram_buffer *buffer = prz->buffer;
286 int ret = unlikely(copy_from_user(buffer->data + start, s, count)) ?
287 -EFAULT : 0;
288 persistent_ram_update_ecc(prz, start, count);
289 return ret;
290}
291
292void persistent_ram_save_old(struct persistent_ram_zone *prz)
293{
294 struct persistent_ram_buffer *buffer = prz->buffer;
295 size_t size = buffer_size(prz);
296 size_t start = buffer_start(prz);
297
298 if (!size)
299 return;
300
301 if (!prz->old_log) {
302 persistent_ram_ecc_old(prz);
303 prz->old_log = kmalloc(size, GFP_KERNEL);
304 }
305 if (!prz->old_log) {
306 pr_err("failed to allocate buffer\n");
307 return;
308 }
309
310 prz->old_log_size = size;
311 memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
312 memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
313}
314
315int notrace persistent_ram_write(struct persistent_ram_zone *prz,
316 const void *s, unsigned int count)
317{
318 int rem;
319 int c = count;
320 size_t start;
321
322 if (unlikely(c > prz->buffer_size)) {
323 s += c - prz->buffer_size;
324 c = prz->buffer_size;
325 }
326
327 buffer_size_add(prz, c);
328
329 start = buffer_start_add(prz, c);
330
331 rem = prz->buffer_size - start;
332 if (unlikely(rem < c)) {
333 persistent_ram_update(prz, s, start, rem);
334 s += rem;
335 c -= rem;
336 start = 0;
337 }
338 persistent_ram_update(prz, s, start, c);
339
340 persistent_ram_update_header_ecc(prz);
341
342 return count;
343}
344
345int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
346 const void __user *s, unsigned int count)
347{
348 int rem, ret = 0, c = count;
349 size_t start;
350
351 if (unlikely(c > prz->buffer_size)) {
352 s += c - prz->buffer_size;
353 c = prz->buffer_size;
354 }
355
356 buffer_size_add(prz, c);
357
358 start = buffer_start_add(prz, c);
359
360 rem = prz->buffer_size - start;
361 if (unlikely(rem < c)) {
362 ret = persistent_ram_update_user(prz, s, start, rem);
363 s += rem;
364 c -= rem;
365 start = 0;
366 }
367 if (likely(!ret))
368 ret = persistent_ram_update_user(prz, s, start, c);
369
370 persistent_ram_update_header_ecc(prz);
371
372 return unlikely(ret) ? ret : count;
373}
374
375size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
376{
377 return prz->old_log_size;
378}
379
380void *persistent_ram_old(struct persistent_ram_zone *prz)
381{
382 return prz->old_log;
383}
384
385void persistent_ram_free_old(struct persistent_ram_zone *prz)
386{
387 kfree(prz->old_log);
388 prz->old_log = NULL;
389 prz->old_log_size = 0;
390}
391
392void persistent_ram_zap(struct persistent_ram_zone *prz)
393{
394 atomic_set(&prz->buffer->start, 0);
395 atomic_set(&prz->buffer->size, 0);
396 persistent_ram_update_header_ecc(prz);
397}
398
399static void *persistent_ram_vmap(phys_addr_t start, size_t size,
400 unsigned int memtype)
401{
402 struct page **pages;
403 phys_addr_t page_start;
404 unsigned int page_count;
405 pgprot_t prot;
406 unsigned int i;
407 void *vaddr;
408
409 page_start = start - offset_in_page(start);
410 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
411
412 if (memtype)
413 prot = pgprot_noncached(PAGE_KERNEL);
414 else
415 prot = pgprot_writecombine(PAGE_KERNEL);
416
417 pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
418 if (!pages) {
419 pr_err("%s: Failed to allocate array for %u pages\n",
420 __func__, page_count);
421 return NULL;
422 }
423
424 for (i = 0; i < page_count; i++) {
425 phys_addr_t addr = page_start + i * PAGE_SIZE;
426 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
427 }
428 vaddr = vmap(pages, page_count, VM_MAP, prot);
429 kfree(pages);
430
431 /*
432 * Since vmap() uses page granularity, we must add the offset
433 * into the page here, to get the byte granularity address
434 * into the mapping to represent the actual "start" location.
435 */
436 return vaddr + offset_in_page(start);
437}
438
439static void *persistent_ram_iomap(phys_addr_t start, size_t size,
440 unsigned int memtype, char *label)
441{
442 void *va;
443
444 if (!request_mem_region(start, size, label ?: "ramoops")) {
445 pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
446 label ?: "ramoops",
447 (unsigned long long)size, (unsigned long long)start);
448 return NULL;
449 }
450
451 if (memtype)
452 va = ioremap(start, size);
453 else
454 va = ioremap_wc(start, size);
455
456 /*
457 * Since request_mem_region() and ioremap() are byte-granularity
458 * there is no need handle anything special like we do when the
459 * vmap() case in persistent_ram_vmap() above.
460 */
461 return va;
462}
463
464static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
465 struct persistent_ram_zone *prz, int memtype)
466{
467 prz->paddr = start;
468 prz->size = size;
469
470 if (pfn_valid(start >> PAGE_SHIFT))
471 prz->vaddr = persistent_ram_vmap(start, size, memtype);
472 else
473 prz->vaddr = persistent_ram_iomap(start, size, memtype,
474 prz->label);
475
476 if (!prz->vaddr) {
477 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
478 (unsigned long long)size, (unsigned long long)start);
479 return -ENOMEM;
480 }
481
482 prz->buffer = prz->vaddr;
483 prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
484
485 return 0;
486}
487
488static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
489 struct persistent_ram_ecc_info *ecc_info)
490{
491 int ret;
492 bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
493
494 ret = persistent_ram_init_ecc(prz, ecc_info);
495 if (ret) {
496 pr_warn("ECC failed %s\n", prz->label);
497 return ret;
498 }
499
500 sig ^= PERSISTENT_RAM_SIG;
501
502 if (prz->buffer->sig == sig) {
503 if (buffer_size(prz) == 0) {
504 pr_debug("found existing empty buffer\n");
505 return 0;
506 }
507
508 if (buffer_size(prz) > prz->buffer_size ||
509 buffer_start(prz) > buffer_size(prz)) {
510 pr_info("found existing invalid buffer, size %zu, start %zu\n",
511 buffer_size(prz), buffer_start(prz));
512 zap = true;
513 } else {
514 pr_debug("found existing buffer, size %zu, start %zu\n",
515 buffer_size(prz), buffer_start(prz));
516 persistent_ram_save_old(prz);
517 }
518 } else {
519 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
520 prz->buffer->sig);
521 prz->buffer->sig = sig;
522 zap = true;
523 }
524
525 /* Reset missing, invalid, or single-use memory area. */
526 if (zap)
527 persistent_ram_zap(prz);
528
529 return 0;
530}
531
532void persistent_ram_free(struct persistent_ram_zone *prz)
533{
534 if (!prz)
535 return;
536
537 if (prz->vaddr) {
538 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
539 /* We must vunmap() at page-granularity. */
540 vunmap(prz->vaddr - offset_in_page(prz->paddr));
541 } else {
542 iounmap(prz->vaddr);
543 release_mem_region(prz->paddr, prz->size);
544 }
545 prz->vaddr = NULL;
546 }
547 if (prz->rs_decoder) {
548 free_rs(prz->rs_decoder);
549 prz->rs_decoder = NULL;
550 }
551 kfree(prz->ecc_info.par);
552 prz->ecc_info.par = NULL;
553
554 persistent_ram_free_old(prz);
555 kfree(prz->label);
556 kfree(prz);
557}
558
559struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
560 u32 sig, struct persistent_ram_ecc_info *ecc_info,
561 unsigned int memtype, u32 flags, char *label)
562{
563 struct persistent_ram_zone *prz;
564 int ret = -ENOMEM;
565
566 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
567 if (!prz) {
568 pr_err("failed to allocate persistent ram zone\n");
569 goto err;
570 }
571
572 /* Initialize general buffer state. */
573 raw_spin_lock_init(&prz->buffer_lock);
574 prz->flags = flags;
575 prz->label = kstrdup(label, GFP_KERNEL);
576
577 ret = persistent_ram_buffer_map(start, size, prz, memtype);
578 if (ret)
579 goto err;
580
581 ret = persistent_ram_post_init(prz, sig, ecc_info);
582 if (ret)
583 goto err;
584
585 pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
586 prz->label, prz->size, (unsigned long long)prz->paddr,
587 sizeof(*prz->buffer), prz->buffer_size,
588 prz->size - sizeof(*prz->buffer) - prz->buffer_size,
589 prz->ecc_info.ecc_size, prz->ecc_info.block_size);
590
591 return prz;
592err:
593 persistent_ram_free(prz);
594 return ERR_PTR(ret);
595}