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