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TOMOYO Linux Cross Reference
Linux/fs/pstore/ram_core.c

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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/kernel.h>
 21 #include <linux/init.h>
 22 #include <linux/io.h>
 23 #include <linux/list.h>
 24 #include <linux/memblock.h>
 25 #include <linux/rslib.h>
 26 #include <linux/slab.h>
 27 #include <linux/vmalloc.h>
 28 #include <linux/pstore_ram.h>
 29 #include <asm/page.h>
 30 
 31 struct persistent_ram_buffer {
 32         uint32_t    sig;
 33         atomic_t    start;
 34         atomic_t    size;
 35         uint8_t     data[0];
 36 };
 37 
 38 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
 39 
 40 static inline size_t buffer_size(struct persistent_ram_zone *prz)
 41 {
 42         return atomic_read(&prz->buffer->size);
 43 }
 44 
 45 static inline size_t buffer_start(struct persistent_ram_zone *prz)
 46 {
 47         return atomic_read(&prz->buffer->start);
 48 }
 49 
 50 /* increase and wrap the start pointer, returning the old value */
 51 static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a)
 52 {
 53         int old;
 54         int new;
 55 
 56         do {
 57                 old = atomic_read(&prz->buffer->start);
 58                 new = old + a;
 59                 while (unlikely(new >= prz->buffer_size))
 60                         new -= prz->buffer_size;
 61         } while (atomic_cmpxchg(&prz->buffer->start, old, new) != old);
 62 
 63         return old;
 64 }
 65 
 66 /* increase the size counter until it hits the max size */
 67 static void buffer_size_add_atomic(struct persistent_ram_zone *prz, size_t a)
 68 {
 69         size_t old;
 70         size_t new;
 71 
 72         if (atomic_read(&prz->buffer->size) == prz->buffer_size)
 73                 return;
 74 
 75         do {
 76                 old = atomic_read(&prz->buffer->size);
 77                 new = old + a;
 78                 if (new > prz->buffer_size)
 79                         new = prz->buffer_size;
 80         } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old);
 81 }
 82 
 83 static DEFINE_RAW_SPINLOCK(buffer_lock);
 84 
 85 /* increase and wrap the start pointer, returning the old value */
 86 static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a)
 87 {
 88         int old;
 89         int new;
 90         unsigned long flags;
 91 
 92         raw_spin_lock_irqsave(&buffer_lock, flags);
 93 
 94         old = atomic_read(&prz->buffer->start);
 95         new = old + a;
 96         while (unlikely(new >= prz->buffer_size))
 97                 new -= prz->buffer_size;
 98         atomic_set(&prz->buffer->start, new);
 99 
100         raw_spin_unlock_irqrestore(&buffer_lock, flags);
101 
102         return old;
103 }
104 
105 /* increase the size counter until it hits the max size */
106 static void buffer_size_add_locked(struct persistent_ram_zone *prz, size_t a)
107 {
108         size_t old;
109         size_t new;
110         unsigned long flags;
111 
112         raw_spin_lock_irqsave(&buffer_lock, flags);
113 
114         old = atomic_read(&prz->buffer->size);
115         if (old == prz->buffer_size)
116                 goto exit;
117 
118         new = old + a;
119         if (new > prz->buffer_size)
120                 new = prz->buffer_size;
121         atomic_set(&prz->buffer->size, new);
122 
123 exit:
124         raw_spin_unlock_irqrestore(&buffer_lock, flags);
125 }
126 
127 static size_t (*buffer_start_add)(struct persistent_ram_zone *, size_t) = buffer_start_add_atomic;
128 static void (*buffer_size_add)(struct persistent_ram_zone *, size_t) = buffer_size_add_atomic;
129 
130 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
131         uint8_t *data, size_t len, uint8_t *ecc)
132 {
133         int i;
134         uint16_t par[prz->ecc_info.ecc_size];
135 
136         /* Initialize the parity buffer */
137         memset(par, 0, sizeof(par));
138         encode_rs8(prz->rs_decoder, data, len, par, 0);
139         for (i = 0; i < prz->ecc_info.ecc_size; i++)
140                 ecc[i] = par[i];
141 }
142 
143 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
144         void *data, size_t len, uint8_t *ecc)
145 {
146         int i;
147         uint16_t par[prz->ecc_info.ecc_size];
148 
149         for (i = 0; i < prz->ecc_info.ecc_size; i++)
150                 par[i] = ecc[i];
151         return decode_rs8(prz->rs_decoder, data, par, len,
152                                 NULL, 0, NULL, 0, NULL);
153 }
154 
155 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
156         unsigned int start, unsigned int count)
157 {
158         struct persistent_ram_buffer *buffer = prz->buffer;
159         uint8_t *buffer_end = buffer->data + prz->buffer_size;
160         uint8_t *block;
161         uint8_t *par;
162         int ecc_block_size = prz->ecc_info.block_size;
163         int ecc_size = prz->ecc_info.ecc_size;
164         int size = ecc_block_size;
165 
166         if (!ecc_size)
167                 return;
168 
169         block = buffer->data + (start & ~(ecc_block_size - 1));
170         par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
171 
172         do {
173                 if (block + ecc_block_size > buffer_end)
174                         size = buffer_end - block;
175                 persistent_ram_encode_rs8(prz, block, size, par);
176                 block += ecc_block_size;
177                 par += ecc_size;
178         } while (block < buffer->data + start + count);
179 }
180 
181 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
182 {
183         struct persistent_ram_buffer *buffer = prz->buffer;
184 
185         if (!prz->ecc_info.ecc_size)
186                 return;
187 
188         persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
189                                   prz->par_header);
190 }
191 
192 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
193 {
194         struct persistent_ram_buffer *buffer = prz->buffer;
195         uint8_t *block;
196         uint8_t *par;
197 
198         if (!prz->ecc_info.ecc_size)
199                 return;
200 
201         block = buffer->data;
202         par = prz->par_buffer;
203         while (block < buffer->data + buffer_size(prz)) {
204                 int numerr;
205                 int size = prz->ecc_info.block_size;
206                 if (block + size > buffer->data + prz->buffer_size)
207                         size = buffer->data + prz->buffer_size - block;
208                 numerr = persistent_ram_decode_rs8(prz, block, size, par);
209                 if (numerr > 0) {
210                         pr_devel("error in block %p, %d\n", block, numerr);
211                         prz->corrected_bytes += numerr;
212                 } else if (numerr < 0) {
213                         pr_devel("uncorrectable error in block %p\n", block);
214                         prz->bad_blocks++;
215                 }
216                 block += prz->ecc_info.block_size;
217                 par += prz->ecc_info.ecc_size;
218         }
219 }
220 
221 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
222                                    struct persistent_ram_ecc_info *ecc_info)
223 {
224         int numerr;
225         struct persistent_ram_buffer *buffer = prz->buffer;
226         int ecc_blocks;
227         size_t ecc_total;
228 
229         if (!ecc_info || !ecc_info->ecc_size)
230                 return 0;
231 
232         prz->ecc_info.block_size = ecc_info->block_size ?: 128;
233         prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
234         prz->ecc_info.symsize = ecc_info->symsize ?: 8;
235         prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
236 
237         ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
238                                   prz->ecc_info.block_size +
239                                   prz->ecc_info.ecc_size);
240         ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
241         if (ecc_total >= prz->buffer_size) {
242                 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
243                        __func__, prz->ecc_info.ecc_size,
244                        ecc_total, prz->buffer_size);
245                 return -EINVAL;
246         }
247 
248         prz->buffer_size -= ecc_total;
249         prz->par_buffer = buffer->data + prz->buffer_size;
250         prz->par_header = prz->par_buffer +
251                           ecc_blocks * prz->ecc_info.ecc_size;
252 
253         /*
254          * first consecutive root is 0
255          * primitive element to generate roots = 1
256          */
257         prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
258                                   0, 1, prz->ecc_info.ecc_size);
259         if (prz->rs_decoder == NULL) {
260                 pr_info("init_rs failed\n");
261                 return -EINVAL;
262         }
263 
264         prz->corrected_bytes = 0;
265         prz->bad_blocks = 0;
266 
267         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
268                                            prz->par_header);
269         if (numerr > 0) {
270                 pr_info("error in header, %d\n", numerr);
271                 prz->corrected_bytes += numerr;
272         } else if (numerr < 0) {
273                 pr_info("uncorrectable error in header\n");
274                 prz->bad_blocks++;
275         }
276 
277         return 0;
278 }
279 
280 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
281         char *str, size_t len)
282 {
283         ssize_t ret;
284 
285         if (!prz->ecc_info.ecc_size)
286                 return 0;
287 
288         if (prz->corrected_bytes || prz->bad_blocks)
289                 ret = snprintf(str, len, ""
290                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
291                         prz->corrected_bytes, prz->bad_blocks);
292         else
293                 ret = snprintf(str, len, "\nNo errors detected\n");
294 
295         return ret;
296 }
297 
298 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
299         const void *s, unsigned int start, unsigned int count)
300 {
301         struct persistent_ram_buffer *buffer = prz->buffer;
302         memcpy(buffer->data + start, s, count);
303         persistent_ram_update_ecc(prz, start, count);
304 }
305 
306 void persistent_ram_save_old(struct persistent_ram_zone *prz)
307 {
308         struct persistent_ram_buffer *buffer = prz->buffer;
309         size_t size = buffer_size(prz);
310         size_t start = buffer_start(prz);
311 
312         if (!size)
313                 return;
314 
315         if (!prz->old_log) {
316                 persistent_ram_ecc_old(prz);
317                 prz->old_log = kmalloc(size, GFP_KERNEL);
318         }
319         if (!prz->old_log) {
320                 pr_err("failed to allocate buffer\n");
321                 return;
322         }
323 
324         prz->old_log_size = size;
325         memcpy(prz->old_log, &buffer->data[start], size - start);
326         memcpy(prz->old_log + size - start, &buffer->data[0], start);
327 }
328 
329 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
330         const void *s, unsigned int count)
331 {
332         int rem;
333         int c = count;
334         size_t start;
335 
336         if (unlikely(c > prz->buffer_size)) {
337                 s += c - prz->buffer_size;
338                 c = prz->buffer_size;
339         }
340 
341         buffer_size_add(prz, c);
342 
343         start = buffer_start_add(prz, c);
344 
345         rem = prz->buffer_size - start;
346         if (unlikely(rem < c)) {
347                 persistent_ram_update(prz, s, start, rem);
348                 s += rem;
349                 c -= rem;
350                 start = 0;
351         }
352         persistent_ram_update(prz, s, start, c);
353 
354         persistent_ram_update_header_ecc(prz);
355 
356         return count;
357 }
358 
359 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
360 {
361         return prz->old_log_size;
362 }
363 
364 void *persistent_ram_old(struct persistent_ram_zone *prz)
365 {
366         return prz->old_log;
367 }
368 
369 void persistent_ram_free_old(struct persistent_ram_zone *prz)
370 {
371         kfree(prz->old_log);
372         prz->old_log = NULL;
373         prz->old_log_size = 0;
374 }
375 
376 void persistent_ram_zap(struct persistent_ram_zone *prz)
377 {
378         atomic_set(&prz->buffer->start, 0);
379         atomic_set(&prz->buffer->size, 0);
380         persistent_ram_update_header_ecc(prz);
381 }
382 
383 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
384                 unsigned int memtype)
385 {
386         struct page **pages;
387         phys_addr_t page_start;
388         unsigned int page_count;
389         pgprot_t prot;
390         unsigned int i;
391         void *vaddr;
392 
393         page_start = start - offset_in_page(start);
394         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
395 
396         if (memtype)
397                 prot = pgprot_noncached(PAGE_KERNEL);
398         else
399                 prot = pgprot_writecombine(PAGE_KERNEL);
400 
401         pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
402         if (!pages) {
403                 pr_err("%s: Failed to allocate array for %u pages\n",
404                        __func__, page_count);
405                 return NULL;
406         }
407 
408         for (i = 0; i < page_count; i++) {
409                 phys_addr_t addr = page_start + i * PAGE_SIZE;
410                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
411         }
412         vaddr = vmap(pages, page_count, VM_MAP, prot);
413         kfree(pages);
414 
415         return vaddr;
416 }
417 
418 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
419                 unsigned int memtype)
420 {
421         void *va;
422 
423         if (!request_mem_region(start, size, "persistent_ram")) {
424                 pr_err("request mem region (0x%llx@0x%llx) failed\n",
425                         (unsigned long long)size, (unsigned long long)start);
426                 return NULL;
427         }
428 
429         buffer_start_add = buffer_start_add_locked;
430         buffer_size_add = buffer_size_add_locked;
431 
432         if (memtype)
433                 va = ioremap(start, size);
434         else
435                 va = ioremap_wc(start, size);
436 
437         return va;
438 }
439 
440 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
441                 struct persistent_ram_zone *prz, int memtype)
442 {
443         prz->paddr = start;
444         prz->size = size;
445 
446         if (pfn_valid(start >> PAGE_SHIFT))
447                 prz->vaddr = persistent_ram_vmap(start, size, memtype);
448         else
449                 prz->vaddr = persistent_ram_iomap(start, size, memtype);
450 
451         if (!prz->vaddr) {
452                 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
453                         (unsigned long long)size, (unsigned long long)start);
454                 return -ENOMEM;
455         }
456 
457         prz->buffer = prz->vaddr + offset_in_page(start);
458         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
459 
460         return 0;
461 }
462 
463 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
464                                     struct persistent_ram_ecc_info *ecc_info)
465 {
466         int ret;
467 
468         ret = persistent_ram_init_ecc(prz, ecc_info);
469         if (ret)
470                 return ret;
471 
472         sig ^= PERSISTENT_RAM_SIG;
473 
474         if (prz->buffer->sig == sig) {
475                 if (buffer_size(prz) > prz->buffer_size ||
476                     buffer_start(prz) > buffer_size(prz))
477                         pr_info("found existing invalid buffer, size %zu, start %zu\n",
478                                 buffer_size(prz), buffer_start(prz));
479                 else {
480                         pr_debug("found existing buffer, size %zu, start %zu\n",
481                                  buffer_size(prz), buffer_start(prz));
482                         persistent_ram_save_old(prz);
483                         return 0;
484                 }
485         } else {
486                 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
487                          prz->buffer->sig);
488         }
489 
490         prz->buffer->sig = sig;
491         persistent_ram_zap(prz);
492 
493         return 0;
494 }
495 
496 void persistent_ram_free(struct persistent_ram_zone *prz)
497 {
498         if (!prz)
499                 return;
500 
501         if (prz->vaddr) {
502                 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
503                         vunmap(prz->vaddr);
504                 } else {
505                         iounmap(prz->vaddr);
506                         release_mem_region(prz->paddr, prz->size);
507                 }
508                 prz->vaddr = NULL;
509         }
510         persistent_ram_free_old(prz);
511         kfree(prz);
512 }
513 
514 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
515                         u32 sig, struct persistent_ram_ecc_info *ecc_info,
516                         unsigned int memtype)
517 {
518         struct persistent_ram_zone *prz;
519         int ret = -ENOMEM;
520 
521         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
522         if (!prz) {
523                 pr_err("failed to allocate persistent ram zone\n");
524                 goto err;
525         }
526 
527         ret = persistent_ram_buffer_map(start, size, prz, memtype);
528         if (ret)
529                 goto err;
530 
531         ret = persistent_ram_post_init(prz, sig, ecc_info);
532         if (ret)
533                 goto err;
534 
535         return prz;
536 err:
537         persistent_ram_free(prz);
538         return ERR_PTR(ret);
539 }
540 

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