2 * Copyright (C) 2012 Google, Inc.
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.
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.
15 #define pr_fmt(fmt) "persistent_ram: " fmt
17 #include <linux/device.h>
18 #include <linux/err.h>
19 #include <linux/errno.h>
20 #include <linux/init.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>
32 struct persistent_ram_buffer {
39 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
41 static inline size_t buffer_size(struct persistent_ram_zone *prz)
43 return atomic_read(&prz->buffer->size);
46 static inline size_t buffer_start(struct persistent_ram_zone *prz)
48 return atomic_read(&prz->buffer->start);
51 /* increase and wrap the start pointer, returning the old value */
52 static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a)
58 old = atomic_read(&prz->buffer->start);
60 while (unlikely(new >= prz->buffer_size))
61 new -= prz->buffer_size;
62 } while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
67 /* increase the size counter until it hits the max size */
68 static void buffer_size_add_atomic(struct persistent_ram_zone *prz, size_t a)
73 if (atomic_read(&prz->buffer->size) == prz->buffer_size)
77 old = atomic_read(&prz->buffer->size);
79 if (new > prz->buffer_size)
80 new = prz->buffer_size;
81 } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
84 static DEFINE_RAW_SPINLOCK(buffer_lock);
86 /* increase and wrap the start pointer, returning the old value */
87 static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
93 raw_spin_lock_irqsave(&buffer_lock, flags);
95 old = atomic_read(&prz->buffer->start);
97 while (unlikely(new >= prz->buffer_size))
98 new -= prz->buffer_size;
99 atomic_set(&prz->buffer->start, new);
101 raw_spin_unlock_irqrestore(&buffer_lock, flags);
106 /* increase the size counter until it hits the max size */
107 static void buffer_size_add_locked(struct persistent_ram_zone *prz, size_t a)
113 raw_spin_lock_irqsave(&buffer_lock, flags);
115 old = atomic_read(&prz->buffer->size);
116 if (old == prz->buffer_size)
120 if (new > prz->buffer_size)
121 new = prz->buffer_size;
122 atomic_set(&prz->buffer->size, new);
125 raw_spin_unlock_irqrestore(&buffer_lock, flags);
128 static size_t (*buffer_start_add)(struct persistent_ram_zone *, size_t) = buffer_start_add_atomic;
129 static void (*buffer_size_add)(struct persistent_ram_zone *, size_t) = buffer_size_add_atomic;
131 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
132 uint8_t *data, size_t len, uint8_t *ecc)
135 uint16_t par[prz->ecc_info.ecc_size];
137 /* Initialize the parity buffer */
138 memset(par, 0, sizeof(par));
139 encode_rs8(prz->rs_decoder, data, len, par, 0);
140 for (i = 0; i < prz->ecc_info.ecc_size; i++)
144 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
145 void *data, size_t len, uint8_t *ecc)
148 uint16_t par[prz->ecc_info.ecc_size];
150 for (i = 0; i < prz->ecc_info.ecc_size; i++)
152 return decode_rs8(prz->rs_decoder, data, par, len,
153 NULL, 0, NULL, 0, NULL);
156 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
157 unsigned int start, unsigned int count)
159 struct persistent_ram_buffer *buffer = prz->buffer;
160 uint8_t *buffer_end = buffer->data + prz->buffer_size;
163 int ecc_block_size = prz->ecc_info.block_size;
164 int ecc_size = prz->ecc_info.ecc_size;
165 int size = ecc_block_size;
170 block = buffer->data + (start & ~(ecc_block_size - 1));
171 par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
174 if (block + ecc_block_size > buffer_end)
175 size = buffer_end - block;
176 persistent_ram_encode_rs8(prz, block, size, par);
177 block += ecc_block_size;
179 } while (block < buffer->data + start + count);
182 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
184 struct persistent_ram_buffer *buffer = prz->buffer;
186 if (!prz->ecc_info.ecc_size)
189 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
193 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
195 struct persistent_ram_buffer *buffer = prz->buffer;
199 if (!prz->ecc_info.ecc_size)
202 block = buffer->data;
203 par = prz->par_buffer;
204 while (block < buffer->data + buffer_size(prz)) {
206 int size = prz->ecc_info.block_size;
207 if (block + size > buffer->data + prz->buffer_size)
208 size = buffer->data + prz->buffer_size - block;
209 numerr = persistent_ram_decode_rs8(prz, block, size, par);
211 pr_devel("error in block %p, %d\n", block, numerr);
212 prz->corrected_bytes += numerr;
213 } else if (numerr < 0) {
214 pr_devel("uncorrectable error in block %p\n", block);
217 block += prz->ecc_info.block_size;
218 par += prz->ecc_info.ecc_size;
222 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
223 struct persistent_ram_ecc_info *ecc_info)
226 struct persistent_ram_buffer *buffer = prz->buffer;
230 if (!ecc_info || !ecc_info->ecc_size)
233 prz->ecc_info.block_size = ecc_info->block_size ?: 128;
234 prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
235 prz->ecc_info.symsize = ecc_info->symsize ?: 8;
236 prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
238 ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
239 prz->ecc_info.block_size +
240 prz->ecc_info.ecc_size);
241 ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
242 if (ecc_total >= prz->buffer_size) {
243 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
244 __func__, prz->ecc_info.ecc_size,
245 ecc_total, prz->buffer_size);
249 prz->buffer_size -= ecc_total;
250 prz->par_buffer = buffer->data + prz->buffer_size;
251 prz->par_header = prz->par_buffer +
252 ecc_blocks * prz->ecc_info.ecc_size;
255 * first consecutive root is 0
256 * primitive element to generate roots = 1
258 prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
259 0, 1, prz->ecc_info.ecc_size);
260 if (prz->rs_decoder == NULL) {
261 pr_info("init_rs failed\n");
265 prz->corrected_bytes = 0;
268 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
271 pr_info("error in header, %d\n", numerr);
272 prz->corrected_bytes += numerr;
273 } else if (numerr < 0) {
274 pr_info("uncorrectable error in header\n");
281 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
282 char *str, size_t len)
286 if (!prz->ecc_info.ecc_size)
289 if (prz->corrected_bytes || prz->bad_blocks)
290 ret = snprintf(str, len, ""
291 "\n%d Corrected bytes, %d unrecoverable blocks\n",
292 prz->corrected_bytes, prz->bad_blocks);
294 ret = snprintf(str, len, "\nNo errors detected\n");
299 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
300 const void *s, unsigned int start, unsigned int count)
302 struct persistent_ram_buffer *buffer = prz->buffer;
303 memcpy(buffer->data + start, s, count);
304 persistent_ram_update_ecc(prz, start, count);
307 static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
308 const void __user *s, unsigned int start, unsigned int count)
310 struct persistent_ram_buffer *buffer = prz->buffer;
311 int ret = unlikely(__copy_from_user(buffer->data + start, s, count)) ?
313 persistent_ram_update_ecc(prz, start, count);
317 void persistent_ram_save_old(struct persistent_ram_zone *prz)
319 struct persistent_ram_buffer *buffer = prz->buffer;
320 size_t size = buffer_size(prz);
321 size_t start = buffer_start(prz);
327 persistent_ram_ecc_old(prz);
328 prz->old_log = kmalloc(size, GFP_KERNEL);
331 pr_err("failed to allocate buffer\n");
335 prz->old_log_size = size;
336 memcpy(prz->old_log, &buffer->data[start], size - start);
337 memcpy(prz->old_log + size - start, &buffer->data[0], start);
340 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
341 const void *s, unsigned int count)
347 if (unlikely(c > prz->buffer_size)) {
348 s += c - prz->buffer_size;
349 c = prz->buffer_size;
352 buffer_size_add(prz, c);
354 start = buffer_start_add(prz, c);
356 rem = prz->buffer_size - start;
357 if (unlikely(rem < c)) {
358 persistent_ram_update(prz, s, start, rem);
363 persistent_ram_update(prz, s, start, c);
365 persistent_ram_update_header_ecc(prz);
370 int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
371 const void __user *s, unsigned int count)
373 int rem, ret = 0, c = count;
376 if (unlikely(!access_ok(VERIFY_READ, s, count)))
378 if (unlikely(c > prz->buffer_size)) {
379 s += c - prz->buffer_size;
380 c = prz->buffer_size;
383 buffer_size_add(prz, c);
385 start = buffer_start_add(prz, c);
387 rem = prz->buffer_size - start;
388 if (unlikely(rem < c)) {
389 ret = persistent_ram_update_user(prz, s, start, rem);
395 ret = persistent_ram_update_user(prz, s, start, c);
397 persistent_ram_update_header_ecc(prz);
399 return unlikely(ret) ? ret : count;
402 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
404 return prz->old_log_size;
407 void *persistent_ram_old(struct persistent_ram_zone *prz)
412 void persistent_ram_free_old(struct persistent_ram_zone *prz)
416 prz->old_log_size = 0;
419 void persistent_ram_zap(struct persistent_ram_zone *prz)
421 atomic_set(&prz->buffer->start, 0);
422 atomic_set(&prz->buffer->size, 0);
423 persistent_ram_update_header_ecc(prz);
426 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
427 unsigned int memtype)
430 phys_addr_t page_start;
431 unsigned int page_count;
436 page_start = start - offset_in_page(start);
437 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
440 prot = pgprot_noncached(PAGE_KERNEL);
442 prot = pgprot_writecombine(PAGE_KERNEL);
444 pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
446 pr_err("%s: Failed to allocate array for %u pages\n",
447 __func__, page_count);
451 for (i = 0; i < page_count; i++) {
452 phys_addr_t addr = page_start + i * PAGE_SIZE;
453 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
455 vaddr = vmap(pages, page_count, VM_MAP, prot);
461 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
462 unsigned int memtype)
466 if (!request_mem_region(start, size, "persistent_ram")) {
467 pr_err("request mem region (0x%llx@0x%llx) failed\n",
468 (unsigned long long)size, (unsigned long long)start);
472 buffer_start_add = buffer_start_add_locked;
473 buffer_size_add = buffer_size_add_locked;
476 va = ioremap(start, size);
478 va = ioremap_wc(start, size);
483 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
484 struct persistent_ram_zone *prz, int memtype)
489 if (pfn_valid(start >> PAGE_SHIFT))
490 prz->vaddr = persistent_ram_vmap(start, size, memtype);
492 prz->vaddr = persistent_ram_iomap(start, size, memtype);
495 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
496 (unsigned long long)size, (unsigned long long)start);
500 prz->buffer = prz->vaddr + offset_in_page(start);
501 prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
506 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
507 struct persistent_ram_ecc_info *ecc_info)
511 ret = persistent_ram_init_ecc(prz, ecc_info);
515 sig ^= PERSISTENT_RAM_SIG;
517 if (prz->buffer->sig == sig) {
518 if (buffer_size(prz) > prz->buffer_size ||
519 buffer_start(prz) > buffer_size(prz))
520 pr_info("found existing invalid buffer, size %zu, start %zu\n",
521 buffer_size(prz), buffer_start(prz));
523 pr_debug("found existing buffer, size %zu, start %zu\n",
524 buffer_size(prz), buffer_start(prz));
525 persistent_ram_save_old(prz);
529 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
533 prz->buffer->sig = sig;
534 persistent_ram_zap(prz);
539 void persistent_ram_free(struct persistent_ram_zone *prz)
545 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
549 release_mem_region(prz->paddr, prz->size);
553 persistent_ram_free_old(prz);
557 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
558 u32 sig, struct persistent_ram_ecc_info *ecc_info,
559 unsigned int memtype)
561 struct persistent_ram_zone *prz;
564 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
566 pr_err("failed to allocate persistent ram zone\n");
570 ret = persistent_ram_buffer_map(start, size, prz, memtype);
574 ret = persistent_ram_post_init(prz, sig, ecc_info);
580 persistent_ram_free(prz);