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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 uint16_t par[prz->ecc_info.ecc_size];
102
103 /* Initialize the parity buffer */
104 memset(par, 0, sizeof(par));
105 encode_rs8(prz->rs_decoder, data, len, par, 0);
106 for (i = 0; i < prz->ecc_info.ecc_size; i++)
107 ecc[i] = 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 uint16_t par[prz->ecc_info.ecc_size];
115
116 for (i = 0; i < prz->ecc_info.ecc_size; i++)
117 par[i] = ecc[i];
118 return decode_rs8(prz->rs_decoder, data, 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 prz->corrected_bytes = 0;
232 prz->bad_blocks = 0;
233
234 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
235 prz->par_header);
236 if (numerr > 0) {
237 pr_info("error in header, %d\n", numerr);
238 prz->corrected_bytes += numerr;
239 } else if (numerr < 0) {
240 pr_info("uncorrectable error in header\n");
241 prz->bad_blocks++;
242 }
243
244 return 0;
245}
246
247ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
248 char *str, size_t len)
249{
250 ssize_t ret;
251
252 if (!prz->ecc_info.ecc_size)
253 return 0;
254
255 if (prz->corrected_bytes || prz->bad_blocks)
256 ret = snprintf(str, len, ""
257 "\n%d Corrected bytes, %d unrecoverable blocks\n",
258 prz->corrected_bytes, prz->bad_blocks);
259 else
260 ret = snprintf(str, len, "\nNo errors detected\n");
261
262 return ret;
263}
264
265static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
266 const void *s, unsigned int start, unsigned int count)
267{
268 struct persistent_ram_buffer *buffer = prz->buffer;
269 memcpy_toio(buffer->data + start, s, count);
270 persistent_ram_update_ecc(prz, start, count);
271}
272
273static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
274 const void __user *s, unsigned int start, unsigned int count)
275{
276 struct persistent_ram_buffer *buffer = prz->buffer;
277 int ret = unlikely(__copy_from_user(buffer->data + start, s, count)) ?
278 -EFAULT : 0;
279 persistent_ram_update_ecc(prz, start, count);
280 return ret;
281}
282
283void persistent_ram_save_old(struct persistent_ram_zone *prz)
284{
285 struct persistent_ram_buffer *buffer = prz->buffer;
286 size_t size = buffer_size(prz);
287 size_t start = buffer_start(prz);
288
289 if (!size)
290 return;
291
292 if (!prz->old_log) {
293 persistent_ram_ecc_old(prz);
294 prz->old_log = kmalloc(size, GFP_KERNEL);
295 }
296 if (!prz->old_log) {
297 pr_err("failed to allocate buffer\n");
298 return;
299 }
300
301 prz->old_log_size = size;
302 memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
303 memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
304}
305
306int notrace persistent_ram_write(struct persistent_ram_zone *prz,
307 const void *s, unsigned int count)
308{
309 int rem;
310 int c = count;
311 size_t start;
312
313 if (unlikely(c > prz->buffer_size)) {
314 s += c - prz->buffer_size;
315 c = prz->buffer_size;
316 }
317
318 buffer_size_add(prz, c);
319
320 start = buffer_start_add(prz, c);
321
322 rem = prz->buffer_size - start;
323 if (unlikely(rem < c)) {
324 persistent_ram_update(prz, s, start, rem);
325 s += rem;
326 c -= rem;
327 start = 0;
328 }
329 persistent_ram_update(prz, s, start, c);
330
331 persistent_ram_update_header_ecc(prz);
332
333 return count;
334}
335
336int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
337 const void __user *s, unsigned int count)
338{
339 int rem, ret = 0, c = count;
340 size_t start;
341
342 if (unlikely(!access_ok(VERIFY_READ, s, count)))
343 return -EFAULT;
344 if (unlikely(c > prz->buffer_size)) {
345 s += c - prz->buffer_size;
346 c = prz->buffer_size;
347 }
348
349 buffer_size_add(prz, c);
350
351 start = buffer_start_add(prz, c);
352
353 rem = prz->buffer_size - start;
354 if (unlikely(rem < c)) {
355 ret = persistent_ram_update_user(prz, s, start, rem);
356 s += rem;
357 c -= rem;
358 start = 0;
359 }
360 if (likely(!ret))
361 ret = persistent_ram_update_user(prz, s, start, c);
362
363 persistent_ram_update_header_ecc(prz);
364
365 return unlikely(ret) ? ret : count;
366}
367
368size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
369{
370 return prz->old_log_size;
371}
372
373void *persistent_ram_old(struct persistent_ram_zone *prz)
374{
375 return prz->old_log;
376}
377
378void persistent_ram_free_old(struct persistent_ram_zone *prz)
379{
380 kfree(prz->old_log);
381 prz->old_log = NULL;
382 prz->old_log_size = 0;
383}
384
385void persistent_ram_zap(struct persistent_ram_zone *prz)
386{
387 atomic_set(&prz->buffer->start, 0);
388 atomic_set(&prz->buffer->size, 0);
389 persistent_ram_update_header_ecc(prz);
390}
391
392static void *persistent_ram_vmap(phys_addr_t start, size_t size,
393 unsigned int memtype)
394{
395 struct page **pages;
396 phys_addr_t page_start;
397 unsigned int page_count;
398 pgprot_t prot;
399 unsigned int i;
400 void *vaddr;
401
402 page_start = start - offset_in_page(start);
403 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
404
405 if (memtype)
406 prot = pgprot_noncached(PAGE_KERNEL);
407 else
408 prot = pgprot_writecombine(PAGE_KERNEL);
409
410 pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
411 if (!pages) {
412 pr_err("%s: Failed to allocate array for %u pages\n",
413 __func__, page_count);
414 return NULL;
415 }
416
417 for (i = 0; i < page_count; i++) {
418 phys_addr_t addr = page_start + i * PAGE_SIZE;
419 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
420 }
421 vaddr = vmap(pages, page_count, VM_MAP, prot);
422 kfree(pages);
423
424 return vaddr;
425}
426
427static void *persistent_ram_iomap(phys_addr_t start, size_t size,
428 unsigned int memtype)
429{
430 void *va;
431
432 if (!request_mem_region(start, size, "persistent_ram")) {
433 pr_err("request mem region (0x%llx@0x%llx) failed\n",
434 (unsigned long long)size, (unsigned long long)start);
435 return NULL;
436 }
437
438 if (memtype)
439 va = ioremap(start, size);
440 else
441 va = ioremap_wc(start, size);
442
443 return va;
444}
445
446static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
447 struct persistent_ram_zone *prz, int memtype)
448{
449 prz->paddr = start;
450 prz->size = size;
451
452 if (pfn_valid(start >> PAGE_SHIFT))
453 prz->vaddr = persistent_ram_vmap(start, size, memtype);
454 else
455 prz->vaddr = persistent_ram_iomap(start, size, memtype);
456
457 if (!prz->vaddr) {
458 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
459 (unsigned long long)size, (unsigned long long)start);
460 return -ENOMEM;
461 }
462
463 prz->buffer = prz->vaddr + offset_in_page(start);
464 prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
465
466 return 0;
467}
468
469static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
470 struct persistent_ram_ecc_info *ecc_info,
471 unsigned long flags)
472{
473 int ret;
474
475 ret = persistent_ram_init_ecc(prz, ecc_info);
476 if (ret)
477 return ret;
478
479 sig ^= PERSISTENT_RAM_SIG;
480
481 if (prz->buffer->sig == sig) {
482 if (buffer_size(prz) > prz->buffer_size ||
483 buffer_start(prz) > buffer_size(prz))
484 pr_info("found existing invalid buffer, size %zu, start %zu\n",
485 buffer_size(prz), buffer_start(prz));
486 else {
487 pr_debug("found existing buffer, size %zu, start %zu\n",
488 buffer_size(prz), buffer_start(prz));
489 persistent_ram_save_old(prz);
490 return 0;
491 }
492 } else {
493 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
494 prz->buffer->sig);
495 }
496
497 prz->buffer->sig = sig;
498 persistent_ram_zap(prz);
499 prz->buffer_lock = __RAW_SPIN_LOCK_UNLOCKED(buffer_lock);
500 prz->flags = flags;
501
502 return 0;
503}
504
505void persistent_ram_free(struct persistent_ram_zone *prz)
506{
507 if (!prz)
508 return;
509
510 if (prz->vaddr) {
511 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
512 vunmap(prz->vaddr);
513 } else {
514 iounmap(prz->vaddr);
515 release_mem_region(prz->paddr, prz->size);
516 }
517 prz->vaddr = NULL;
518 }
519 persistent_ram_free_old(prz);
520 kfree(prz);
521}
522
523struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
524 u32 sig, struct persistent_ram_ecc_info *ecc_info,
525 unsigned int memtype, u32 flags)
526{
527 struct persistent_ram_zone *prz;
528 int ret = -ENOMEM;
529
530 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
531 if (!prz) {
532 pr_err("failed to allocate persistent ram zone\n");
533 goto err;
534 }
535
536 ret = persistent_ram_buffer_map(start, size, prz, memtype);
537 if (ret)
538 goto err;
539
540 ret = persistent_ram_post_init(prz, sig, ecc_info, flags);
541 if (ret)
542 goto err;
543
544 return prz;
545err:
546 persistent_ram_free(prz);
547 return ERR_PTR(ret);
548}