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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/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 
 32 struct 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 
 41 static inline size_t buffer_size(struct persistent_ram_zone *prz)
 42 {
 43         return atomic_read(&prz->buffer->size);
 44 }
 45 
 46 static 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 */
 52 static 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 */
 74 static 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 
 92 exit:
 93         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
 94                 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
 95 }
 96 
 97 static 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 
110 static 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 
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 
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 
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 
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         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 
247 ssize_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 
265 static 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 
273 static 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 
283 void 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 
306 int 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 
336 int 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 
368 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
369 {
370         return prz->old_log_size;
371 }
372 
373 void *persistent_ram_old(struct persistent_ram_zone *prz)
374 {
375         return prz->old_log;
376 }
377 
378 void 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 
385 void 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 
392 static 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 
427 static 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 
446 static 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 
469 static 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 
505 void 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 
523 struct 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;
545 err:
546         persistent_ram_free(prz);
547         return ERR_PTR(ret);
548 }
549 

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