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/rslib.h>
17 #include <linux/slab.h>
18 #include <linux/uaccess.h>
19 #include <linux/vmalloc.h>
20 #include <linux/mm.h>
21 #include <asm/page.h>
22
23 #include "ram_internal.h"
24
25 /**
26 * struct persistent_ram_buffer - persistent circular RAM buffer
27 *
28 * @sig: Signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
29 * @start: First valid byte in the buffer.
30 * @size: Number of valid bytes in the buffer.
31 * @data: The contents of the buffer.
32 */
33 struct 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
42 static inline size_t buffer_size(struct persistent_ram_zone *prz)
43 {
44 return atomic_read(&prz->buffer->size);
45 }
46
47 static 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 */
53 static 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 */
75 static 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
93 exit:
94 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
95 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
96 }
97
98 static 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
111 static 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
122 static 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
148 static 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
159 static 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
188 static 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 size_t 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_ratelimited("uncorrectable error in header\n");
250 prz->bad_blocks++;
251 }
252
253 return 0;
254 }
255
256 ssize_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 "\nECC: %d Corrected bytes, %d unrecoverable blocks\n",
267 prz->corrected_bytes, prz->bad_blocks);
268 else
269 ret = snprintf(str, len, "\nECC: No errors detected\n");
270
271 return ret;
272 }
273
274 static 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
282 static 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
292 void 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 = kvzalloc(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
315 int 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
345 int 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
375 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
376 {
377 return prz->old_log_size;
378 }
379
380 void *persistent_ram_old(struct persistent_ram_zone *prz)
381 {
382 return prz->old_log;
383 }
384
385 void persistent_ram_free_old(struct persistent_ram_zone *prz)
386 {
387 kvfree(prz->old_log);
388 prz->old_log = NULL;
389 prz->old_log_size = 0;
390 }
391
392 void 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
399 #define MEM_TYPE_WCOMBINE 0
400 #define MEM_TYPE_NONCACHED 1
401 #define MEM_TYPE_NORMAL 2
402
403 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
404 unsigned int memtype)
405 {
406 struct page **pages;
407 phys_addr_t page_start;
408 unsigned int page_count;
409 pgprot_t prot;
410 unsigned int i;
411 void *vaddr;
412
413 page_start = start - offset_in_page(start);
414 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
415
416 switch (memtype) {
417 case MEM_TYPE_NORMAL:
418 prot = PAGE_KERNEL;
419 break;
420 case MEM_TYPE_NONCACHED:
421 prot = pgprot_noncached(PAGE_KERNEL);
422 break;
423 case MEM_TYPE_WCOMBINE:
424 prot = pgprot_writecombine(PAGE_KERNEL);
425 break;
426 default:
427 pr_err("invalid mem_type=%d\n", memtype);
428 return NULL;
429 }
430
431 pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
432 if (!pages) {
433 pr_err("%s: Failed to allocate array for %u pages\n",
434 __func__, page_count);
435 return NULL;
436 }
437
438 for (i = 0; i < page_count; i++) {
439 phys_addr_t addr = page_start + i * PAGE_SIZE;
440 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
441 }
442 /*
443 * VM_IOREMAP used here to bypass this region during vread()
444 * and kmap_atomic() (i.e. kcore) to avoid __va() failures.
445 */
446 vaddr = vmap(pages, page_count, VM_MAP | VM_IOREMAP, prot);
447 kfree(pages);
448
449 /*
450 * Since vmap() uses page granularity, we must add the offset
451 * into the page here, to get the byte granularity address
452 * into the mapping to represent the actual "start" location.
453 */
454 return vaddr + offset_in_page(start);
455 }
456
457 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
458 unsigned int memtype, char *label)
459 {
460 void *va;
461
462 if (!request_mem_region(start, size, label ?: "ramoops")) {
463 pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
464 label ?: "ramoops",
465 (unsigned long long)size, (unsigned long long)start);
466 return NULL;
467 }
468
469 if (memtype)
470 va = ioremap(start, size);
471 else
472 va = ioremap_wc(start, size);
473
474 /*
475 * Since request_mem_region() and ioremap() are byte-granularity
476 * there is no need handle anything special like we do when the
477 * vmap() case in persistent_ram_vmap() above.
478 */
479 return va;
480 }
481
482 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
483 struct persistent_ram_zone *prz, int memtype)
484 {
485 prz->paddr = start;
486 prz->size = size;
487
488 if (pfn_valid(start >> PAGE_SHIFT))
489 prz->vaddr = persistent_ram_vmap(start, size, memtype);
490 else
491 prz->vaddr = persistent_ram_iomap(start, size, memtype,
492 prz->label);
493
494 if (!prz->vaddr) {
495 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
496 (unsigned long long)size, (unsigned long long)start);
497 return -ENOMEM;
498 }
499
500 prz->buffer = prz->vaddr;
501 prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
502
503 return 0;
504 }
505
506 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
507 struct persistent_ram_ecc_info *ecc_info)
508 {
509 int ret;
510 bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
511
512 ret = persistent_ram_init_ecc(prz, ecc_info);
513 if (ret) {
514 pr_warn("ECC failed %s\n", prz->label);
515 return ret;
516 }
517
518 sig ^= PERSISTENT_RAM_SIG;
519
520 if (prz->buffer->sig == sig) {
521 if (buffer_size(prz) == 0 && buffer_start(prz) == 0) {
522 pr_debug("found existing empty buffer\n");
523 return 0;
524 }
525
526 if (buffer_size(prz) > prz->buffer_size ||
527 buffer_start(prz) > buffer_size(prz)) {
528 pr_info("found existing invalid buffer, size %zu, start %zu\n",
529 buffer_size(prz), buffer_start(prz));
530 zap = true;
531 } else {
532 pr_debug("found existing buffer, size %zu, start %zu\n",
533 buffer_size(prz), buffer_start(prz));
534 persistent_ram_save_old(prz);
535 }
536 } else {
537 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
538 prz->buffer->sig);
539 prz->buffer->sig = sig;
540 zap = true;
541 }
542
543 /* Reset missing, invalid, or single-use memory area. */
544 if (zap)
545 persistent_ram_zap(prz);
546
547 return 0;
548 }
549
550 void persistent_ram_free(struct persistent_ram_zone **_prz)
551 {
552 struct persistent_ram_zone *prz;
553
554 if (!_prz)
555 return;
556
557 prz = *_prz;
558 if (!prz)
559 return;
560
561 if (prz->vaddr) {
562 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
563 /* We must vunmap() at page-granularity. */
564 vunmap(prz->vaddr - offset_in_page(prz->paddr));
565 } else {
566 iounmap(prz->vaddr);
567 release_mem_region(prz->paddr, prz->size);
568 }
569 prz->vaddr = NULL;
570 }
571 if (prz->rs_decoder) {
572 free_rs(prz->rs_decoder);
573 prz->rs_decoder = NULL;
574 }
575 kfree(prz->ecc_info.par);
576 prz->ecc_info.par = NULL;
577
578 persistent_ram_free_old(prz);
579 kfree(prz->label);
580 kfree(prz);
581 *_prz = NULL;
582 }
583
584 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
585 u32 sig, struct persistent_ram_ecc_info *ecc_info,
586 unsigned int memtype, u32 flags, char *label)
587 {
588 struct persistent_ram_zone *prz;
589 int ret = -ENOMEM;
590
591 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
592 if (!prz) {
593 pr_err("failed to allocate persistent ram zone\n");
594 goto err;
595 }
596
597 /* Initialize general buffer state. */
598 raw_spin_lock_init(&prz->buffer_lock);
599 prz->flags = flags;
600 prz->label = kstrdup(label, GFP_KERNEL);
601 if (!prz->label)
602 goto err;
603
604 ret = persistent_ram_buffer_map(start, size, prz, memtype);
605 if (ret)
606 goto err;
607
608 ret = persistent_ram_post_init(prz, sig, ecc_info);
609 if (ret)
610 goto err;
611
612 pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
613 prz->label, prz->size, (unsigned long long)prz->paddr,
614 sizeof(*prz->buffer), prz->buffer_size,
615 prz->size - sizeof(*prz->buffer) - prz->buffer_size,
616 prz->ecc_info.ecc_size, prz->ecc_info.block_size);
617
618 return prz;
619 err:
620 persistent_ram_free(&prz);
621 return ERR_PTR(ret);
622 }
623
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