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 */
33 struct persistent_ram_buffer {
34 uint32_t sig;
35 atomic_t start;
36 atomic_t size;
37 uint8_t data[0];
38 };
39
40 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
41
buffer_size(struct persistent_ram_zone * prz)42 static inline size_t buffer_size(struct persistent_ram_zone *prz)
43 {
44 return atomic_read(&prz->buffer->size);
45 }
46
buffer_start(struct persistent_ram_zone * prz)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 */
buffer_start_add(struct persistent_ram_zone * prz,size_t a)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 */
buffer_size_add(struct persistent_ram_zone * prz,size_t a)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
persistent_ram_encode_rs8(struct persistent_ram_zone * prz,uint8_t * data,size_t len,uint8_t * ecc)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
persistent_ram_decode_rs8(struct persistent_ram_zone * prz,void * data,size_t len,uint8_t * ecc)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
persistent_ram_update_ecc(struct persistent_ram_zone * prz,unsigned int start,unsigned int count)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
persistent_ram_update_header_ecc(struct persistent_ram_zone * prz)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
persistent_ram_ecc_old(struct persistent_ram_zone * prz)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
persistent_ram_init_ecc(struct persistent_ram_zone * prz,struct persistent_ram_ecc_info * ecc_info)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 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
persistent_ram_ecc_string(struct persistent_ram_zone * prz,char * str,size_t len)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 "\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
persistent_ram_update(struct persistent_ram_zone * prz,const void * s,unsigned int start,unsigned int count)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
persistent_ram_update_user(struct persistent_ram_zone * prz,const void __user * s,unsigned int start,unsigned int count)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
persistent_ram_save_old(struct persistent_ram_zone * prz)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 = 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
persistent_ram_write(struct persistent_ram_zone * prz,const void * s,unsigned int count)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
persistent_ram_write_user(struct persistent_ram_zone * prz,const void __user * s,unsigned int count)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(!access_ok(s, count)))
352 return -EFAULT;
353 if (unlikely(c > prz->buffer_size)) {
354 s += c - prz->buffer_size;
355 c = prz->buffer_size;
356 }
357
358 buffer_size_add(prz, c);
359
360 start = buffer_start_add(prz, c);
361
362 rem = prz->buffer_size - start;
363 if (unlikely(rem < c)) {
364 ret = persistent_ram_update_user(prz, s, start, rem);
365 s += rem;
366 c -= rem;
367 start = 0;
368 }
369 if (likely(!ret))
370 ret = persistent_ram_update_user(prz, s, start, c);
371
372 persistent_ram_update_header_ecc(prz);
373
374 return unlikely(ret) ? ret : count;
375 }
376
persistent_ram_old_size(struct persistent_ram_zone * prz)377 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
378 {
379 return prz->old_log_size;
380 }
381
persistent_ram_old(struct persistent_ram_zone * prz)382 void *persistent_ram_old(struct persistent_ram_zone *prz)
383 {
384 return prz->old_log;
385 }
386
persistent_ram_free_old(struct persistent_ram_zone * prz)387 void persistent_ram_free_old(struct persistent_ram_zone *prz)
388 {
389 kfree(prz->old_log);
390 prz->old_log = NULL;
391 prz->old_log_size = 0;
392 }
393
persistent_ram_zap(struct persistent_ram_zone * prz)394 void persistent_ram_zap(struct persistent_ram_zone *prz)
395 {
396 atomic_set(&prz->buffer->start, 0);
397 atomic_set(&prz->buffer->size, 0);
398 persistent_ram_update_header_ecc(prz);
399 }
400
persistent_ram_vmap(phys_addr_t start,size_t size,unsigned int memtype)401 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
402 unsigned int memtype)
403 {
404 struct page **pages;
405 phys_addr_t page_start;
406 unsigned int page_count;
407 pgprot_t prot;
408 unsigned int i;
409 void *vaddr;
410
411 page_start = start - offset_in_page(start);
412 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
413
414 if (memtype)
415 prot = pgprot_noncached(PAGE_KERNEL);
416 else
417 prot = pgprot_writecombine(PAGE_KERNEL);
418
419 pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
420 if (!pages) {
421 pr_err("%s: Failed to allocate array for %u pages\n",
422 __func__, page_count);
423 return NULL;
424 }
425
426 for (i = 0; i < page_count; i++) {
427 phys_addr_t addr = page_start + i * PAGE_SIZE;
428 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
429 }
430 vaddr = vmap(pages, page_count, VM_MAP, prot);
431 kfree(pages);
432
433 /*
434 * Since vmap() uses page granularity, we must add the offset
435 * into the page here, to get the byte granularity address
436 * into the mapping to represent the actual "start" location.
437 */
438 return vaddr + offset_in_page(start);
439 }
440
persistent_ram_iomap(phys_addr_t start,size_t size,unsigned int memtype,char * label)441 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
442 unsigned int memtype, char *label)
443 {
444 void *va;
445
446 if (!request_mem_region(start, size, label ?: "ramoops")) {
447 pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
448 label ?: "ramoops",
449 (unsigned long long)size, (unsigned long long)start);
450 return NULL;
451 }
452
453 if (memtype)
454 va = ioremap(start, size);
455 else
456 va = ioremap_wc(start, size);
457
458 /*
459 * Since request_mem_region() and ioremap() are byte-granularity
460 * there is no need handle anything special like we do when the
461 * vmap() case in persistent_ram_vmap() above.
462 */
463 return va;
464 }
465
persistent_ram_buffer_map(phys_addr_t start,phys_addr_t size,struct persistent_ram_zone * prz,int memtype)466 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
467 struct persistent_ram_zone *prz, int memtype)
468 {
469 prz->paddr = start;
470 prz->size = size;
471
472 if (pfn_valid(start >> PAGE_SHIFT))
473 prz->vaddr = persistent_ram_vmap(start, size, memtype);
474 else
475 prz->vaddr = persistent_ram_iomap(start, size, memtype,
476 prz->label);
477
478 if (!prz->vaddr) {
479 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
480 (unsigned long long)size, (unsigned long long)start);
481 return -ENOMEM;
482 }
483
484 prz->buffer = prz->vaddr;
485 prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
486
487 return 0;
488 }
489
persistent_ram_post_init(struct persistent_ram_zone * prz,u32 sig,struct persistent_ram_ecc_info * ecc_info)490 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
491 struct persistent_ram_ecc_info *ecc_info)
492 {
493 int ret;
494 bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
495
496 ret = persistent_ram_init_ecc(prz, ecc_info);
497 if (ret) {
498 pr_warn("ECC failed %s\n", prz->label);
499 return ret;
500 }
501
502 sig ^= PERSISTENT_RAM_SIG;
503
504 if (prz->buffer->sig == sig) {
505 if (buffer_size(prz) == 0) {
506 pr_debug("found existing empty buffer\n");
507 return 0;
508 }
509
510 if (buffer_size(prz) > prz->buffer_size ||
511 buffer_start(prz) > buffer_size(prz)) {
512 pr_info("found existing invalid buffer, size %zu, start %zu\n",
513 buffer_size(prz), buffer_start(prz));
514 zap = true;
515 } else {
516 pr_debug("found existing buffer, size %zu, start %zu\n",
517 buffer_size(prz), buffer_start(prz));
518 persistent_ram_save_old(prz);
519 }
520 } else {
521 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
522 prz->buffer->sig);
523 prz->buffer->sig = sig;
524 zap = true;
525 }
526
527 /* Reset missing, invalid, or single-use memory area. */
528 if (zap)
529 persistent_ram_zap(prz);
530
531 return 0;
532 }
533
persistent_ram_free(struct persistent_ram_zone * prz)534 void persistent_ram_free(struct persistent_ram_zone *prz)
535 {
536 if (!prz)
537 return;
538
539 if (prz->vaddr) {
540 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
541 /* We must vunmap() at page-granularity. */
542 vunmap(prz->vaddr - offset_in_page(prz->paddr));
543 } else {
544 iounmap(prz->vaddr);
545 release_mem_region(prz->paddr, prz->size);
546 }
547 prz->vaddr = NULL;
548 }
549 if (prz->rs_decoder) {
550 free_rs(prz->rs_decoder);
551 prz->rs_decoder = NULL;
552 }
553 kfree(prz->ecc_info.par);
554 prz->ecc_info.par = NULL;
555
556 persistent_ram_free_old(prz);
557 kfree(prz->label);
558 kfree(prz);
559 }
560
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)561 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
562 u32 sig, struct persistent_ram_ecc_info *ecc_info,
563 unsigned int memtype, u32 flags, char *label)
564 {
565 struct persistent_ram_zone *prz;
566 int ret = -ENOMEM;
567
568 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
569 if (!prz) {
570 pr_err("failed to allocate persistent ram zone\n");
571 goto err;
572 }
573
574 /* Initialize general buffer state. */
575 raw_spin_lock_init(&prz->buffer_lock);
576 prz->flags = flags;
577 prz->label = kstrdup(label, GFP_KERNEL);
578
579 ret = persistent_ram_buffer_map(start, size, prz, memtype);
580 if (ret)
581 goto err;
582
583 ret = persistent_ram_post_init(prz, sig, ecc_info);
584 if (ret)
585 goto err;
586
587 pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
588 prz->label, prz->size, (unsigned long long)prz->paddr,
589 sizeof(*prz->buffer), prz->buffer_size,
590 prz->size - sizeof(*prz->buffer) - prz->buffer_size,
591 prz->ecc_info.ecc_size, prz->ecc_info.block_size);
592
593 return prz;
594 err:
595 persistent_ram_free(prz);
596 return ERR_PTR(ret);
597 }
598