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

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  1 // SPDX-License-Identifier: GPL-2.0-only
  2 /*
  3  * Copyright (C) 2012 Google, Inc.
  4  */
  5 
  6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  7 
  8 #include <linux/device.h>
  9 #include <linux/err.h>
 10 #include <linux/errno.h>
 11 #include <linux/init.h>
 12 #include <linux/io.h>
 13 #include <linux/kernel.h>
 14 #include <linux/list.h>
 15 #include <linux/memblock.h>
 16 #include <linux/pstore_ram.h>
 17 #include <linux/rslib.h>
 18 #include <linux/slab.h>
 19 #include <linux/uaccess.h>
 20 #include <linux/vmalloc.h>
 21 #include <asm/page.h>
 22 
 23 /**
 24  * struct persistent_ram_buffer - persistent circular RAM buffer
 25  *
 26  * @sig:
 27  *      signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
 28  * @start:
 29  *      offset into @data where the beginning of the stored bytes begin
 30  * @size:
 31  *      number of valid bytes stored in @data
 32  */
 33 struct persistent_ram_buffer {
 34         uint32_t    sig;
 35         atomic_t    start;
 36         atomic_t    size;
 37         uint8_t     data[];
 38 };
 39 
 40 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
 41 
 42 static inline size_t buffer_size(struct persistent_ram_zone *prz)
 43 {
 44         return atomic_read(&prz->buffer->size);
 45 }
 46 
 47 static inline size_t buffer_start(struct persistent_ram_zone *prz)
 48 {
 49         return atomic_read(&prz->buffer->start);
 50 }
 51 
 52 /* increase and wrap the start pointer, returning the old value */
 53 static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
 54 {
 55         int old;
 56         int new;
 57         unsigned long flags = 0;
 58 
 59         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
 60                 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
 61 
 62         old = atomic_read(&prz->buffer->start);
 63         new = old + a;
 64         while (unlikely(new >= prz->buffer_size))
 65                 new -= prz->buffer_size;
 66         atomic_set(&prz->buffer->start, new);
 67 
 68         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
 69                 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
 70 
 71         return old;
 72 }
 73 
 74 /* increase the size counter until it hits the max size */
 75 static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
 76 {
 77         size_t old;
 78         size_t new;
 79         unsigned long flags = 0;
 80 
 81         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
 82                 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
 83 
 84         old = atomic_read(&prz->buffer->size);
 85         if (old == prz->buffer_size)
 86                 goto exit;
 87 
 88         new = old + a;
 89         if (new > prz->buffer_size)
 90                 new = prz->buffer_size;
 91         atomic_set(&prz->buffer->size, new);
 92 
 93 exit:
 94         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
 95                 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
 96 }
 97 
 98 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
 99         uint8_t *data, size_t len, uint8_t *ecc)
100 {
101         int i;
102 
103         /* Initialize the parity buffer */
104         memset(prz->ecc_info.par, 0,
105                prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));
106         encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);
107         for (i = 0; i < prz->ecc_info.ecc_size; i++)
108                 ecc[i] = prz->ecc_info.par[i];
109 }
110 
111 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
112         void *data, size_t len, uint8_t *ecc)
113 {
114         int i;
115 
116         for (i = 0; i < prz->ecc_info.ecc_size; i++)
117                 prz->ecc_info.par[i] = ecc[i];
118         return decode_rs8(prz->rs_decoder, data, prz->ecc_info.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         /* allocate workspace instead of using stack VLA */
232         prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,
233                                           sizeof(*prz->ecc_info.par),
234                                           GFP_KERNEL);
235         if (!prz->ecc_info.par) {
236                 pr_err("cannot allocate ECC parity workspace\n");
237                 return -ENOMEM;
238         }
239 
240         prz->corrected_bytes = 0;
241         prz->bad_blocks = 0;
242 
243         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
244                                            prz->par_header);
245         if (numerr > 0) {
246                 pr_info("error in header, %d\n", numerr);
247                 prz->corrected_bytes += numerr;
248         } else if (numerr < 0) {
249                 pr_info_ratelimited("uncorrectable error in header\n");
250                 prz->bad_blocks++;
251         }
252 
253         return 0;
254 }
255 
256 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
257         char *str, size_t len)
258 {
259         ssize_t ret;
260 
261         if (!prz->ecc_info.ecc_size)
262                 return 0;
263 
264         if (prz->corrected_bytes || prz->bad_blocks)
265                 ret = snprintf(str, len, ""
266                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
267                         prz->corrected_bytes, prz->bad_blocks);
268         else
269                 ret = snprintf(str, len, "\nNo errors detected\n");
270 
271         return ret;
272 }
273 
274 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
275         const void *s, unsigned int start, unsigned int count)
276 {
277         struct persistent_ram_buffer *buffer = prz->buffer;
278         memcpy_toio(buffer->data + start, s, count);
279         persistent_ram_update_ecc(prz, start, count);
280 }
281 
282 static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
283         const void __user *s, unsigned int start, unsigned int count)
284 {
285         struct persistent_ram_buffer *buffer = prz->buffer;
286         int ret = unlikely(copy_from_user(buffer->data + start, s, count)) ?
287                 -EFAULT : 0;
288         persistent_ram_update_ecc(prz, start, count);
289         return ret;
290 }
291 
292 void persistent_ram_save_old(struct persistent_ram_zone *prz)
293 {
294         struct persistent_ram_buffer *buffer = prz->buffer;
295         size_t size = buffer_size(prz);
296         size_t start = buffer_start(prz);
297 
298         if (!size)
299                 return;
300 
301         if (!prz->old_log) {
302                 persistent_ram_ecc_old(prz);
303                 prz->old_log = kmalloc(size, GFP_KERNEL);
304         }
305         if (!prz->old_log) {
306                 pr_err("failed to allocate buffer\n");
307                 return;
308         }
309 
310         prz->old_log_size = size;
311         memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
312         memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
313 }
314 
315 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
316         const void *s, unsigned int count)
317 {
318         int rem;
319         int c = count;
320         size_t start;
321 
322         if (unlikely(c > prz->buffer_size)) {
323                 s += c - prz->buffer_size;
324                 c = prz->buffer_size;
325         }
326 
327         buffer_size_add(prz, c);
328 
329         start = buffer_start_add(prz, c);
330 
331         rem = prz->buffer_size - start;
332         if (unlikely(rem < c)) {
333                 persistent_ram_update(prz, s, start, rem);
334                 s += rem;
335                 c -= rem;
336                 start = 0;
337         }
338         persistent_ram_update(prz, s, start, c);
339 
340         persistent_ram_update_header_ecc(prz);
341 
342         return count;
343 }
344 
345 int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
346         const void __user *s, unsigned int count)
347 {
348         int rem, ret = 0, c = count;
349         size_t start;
350 
351         if (unlikely(c > prz->buffer_size)) {
352                 s += c - prz->buffer_size;
353                 c = prz->buffer_size;
354         }
355 
356         buffer_size_add(prz, c);
357 
358         start = buffer_start_add(prz, c);
359 
360         rem = prz->buffer_size - start;
361         if (unlikely(rem < c)) {
362                 ret = persistent_ram_update_user(prz, s, start, rem);
363                 s += rem;
364                 c -= rem;
365                 start = 0;
366         }
367         if (likely(!ret))
368                 ret = persistent_ram_update_user(prz, s, start, c);
369 
370         persistent_ram_update_header_ecc(prz);
371 
372         return unlikely(ret) ? ret : count;
373 }
374 
375 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
376 {
377         return prz->old_log_size;
378 }
379 
380 void *persistent_ram_old(struct persistent_ram_zone *prz)
381 {
382         return prz->old_log;
383 }
384 
385 void persistent_ram_free_old(struct persistent_ram_zone *prz)
386 {
387         kfree(prz->old_log);
388         prz->old_log = NULL;
389         prz->old_log_size = 0;
390 }
391 
392 void persistent_ram_zap(struct persistent_ram_zone *prz)
393 {
394         atomic_set(&prz->buffer->start, 0);
395         atomic_set(&prz->buffer->size, 0);
396         persistent_ram_update_header_ecc(prz);
397 }
398 
399 #define MEM_TYPE_WCOMBINE       0
400 #define MEM_TYPE_NONCACHED      1
401 #define MEM_TYPE_NORMAL         2
402 
403 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
404                 unsigned int memtype)
405 {
406         struct page **pages;
407         phys_addr_t page_start;
408         unsigned int page_count;
409         pgprot_t prot;
410         unsigned int i;
411         void *vaddr;
412 
413         page_start = start - offset_in_page(start);
414         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
415 
416         switch (memtype) {
417         case MEM_TYPE_NORMAL:
418                 prot = PAGE_KERNEL;
419                 break;
420         case MEM_TYPE_NONCACHED:
421                 prot = pgprot_noncached(PAGE_KERNEL);
422                 break;
423         case MEM_TYPE_WCOMBINE:
424                 prot = pgprot_writecombine(PAGE_KERNEL);
425                 break;
426         default:
427                 pr_err("invalid mem_type=%d\n", memtype);
428                 return NULL;
429         }
430 
431         pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
432         if (!pages) {
433                 pr_err("%s: Failed to allocate array for %u pages\n",
434                        __func__, page_count);
435                 return NULL;
436         }
437 
438         for (i = 0; i < page_count; i++) {
439                 phys_addr_t addr = page_start + i * PAGE_SIZE;
440                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
441         }
442         vaddr = vmap(pages, page_count, VM_MAP, prot);
443         kfree(pages);
444 
445         /*
446          * Since vmap() uses page granularity, we must add the offset
447          * into the page here, to get the byte granularity address
448          * into the mapping to represent the actual "start" location.
449          */
450         return vaddr + offset_in_page(start);
451 }
452 
453 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
454                 unsigned int memtype, char *label)
455 {
456         void *va;
457 
458         if (!request_mem_region(start, size, label ?: "ramoops")) {
459                 pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
460                         label ?: "ramoops",
461                         (unsigned long long)size, (unsigned long long)start);
462                 return NULL;
463         }
464 
465         if (memtype)
466                 va = ioremap(start, size);
467         else
468                 va = ioremap_wc(start, size);
469 
470         /*
471          * Since request_mem_region() and ioremap() are byte-granularity
472          * there is no need handle anything special like we do when the
473          * vmap() case in persistent_ram_vmap() above.
474          */
475         return va;
476 }
477 
478 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
479                 struct persistent_ram_zone *prz, int memtype)
480 {
481         prz->paddr = start;
482         prz->size = size;
483 
484         if (pfn_valid(start >> PAGE_SHIFT))
485                 prz->vaddr = persistent_ram_vmap(start, size, memtype);
486         else
487                 prz->vaddr = persistent_ram_iomap(start, size, memtype,
488                                                   prz->label);
489 
490         if (!prz->vaddr) {
491                 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
492                         (unsigned long long)size, (unsigned long long)start);
493                 return -ENOMEM;
494         }
495 
496         prz->buffer = prz->vaddr;
497         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
498 
499         return 0;
500 }
501 
502 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
503                                     struct persistent_ram_ecc_info *ecc_info)
504 {
505         int ret;
506         bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
507 
508         ret = persistent_ram_init_ecc(prz, ecc_info);
509         if (ret) {
510                 pr_warn("ECC failed %s\n", prz->label);
511                 return ret;
512         }
513 
514         sig ^= PERSISTENT_RAM_SIG;
515 
516         if (prz->buffer->sig == sig) {
517                 if (buffer_size(prz) == 0) {
518                         pr_debug("found existing empty buffer\n");
519                         return 0;
520                 }
521 
522                 if (buffer_size(prz) > prz->buffer_size ||
523                     buffer_start(prz) > buffer_size(prz)) {
524                         pr_info("found existing invalid buffer, size %zu, start %zu\n",
525                                 buffer_size(prz), buffer_start(prz));
526                         zap = true;
527                 } else {
528                         pr_debug("found existing buffer, size %zu, start %zu\n",
529                                  buffer_size(prz), buffer_start(prz));
530                         persistent_ram_save_old(prz);
531                 }
532         } else {
533                 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
534                          prz->buffer->sig);
535                 prz->buffer->sig = sig;
536                 zap = true;
537         }
538 
539         /* Reset missing, invalid, or single-use memory area. */
540         if (zap)
541                 persistent_ram_zap(prz);
542 
543         return 0;
544 }
545 
546 void persistent_ram_free(struct persistent_ram_zone *prz)
547 {
548         if (!prz)
549                 return;
550 
551         if (prz->vaddr) {
552                 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
553                         /* We must vunmap() at page-granularity. */
554                         vunmap(prz->vaddr - offset_in_page(prz->paddr));
555                 } else {
556                         iounmap(prz->vaddr);
557                         release_mem_region(prz->paddr, prz->size);
558                 }
559                 prz->vaddr = NULL;
560         }
561         if (prz->rs_decoder) {
562                 free_rs(prz->rs_decoder);
563                 prz->rs_decoder = NULL;
564         }
565         kfree(prz->ecc_info.par);
566         prz->ecc_info.par = NULL;
567 
568         persistent_ram_free_old(prz);
569         kfree(prz->label);
570         kfree(prz);
571 }
572 
573 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
574                         u32 sig, struct persistent_ram_ecc_info *ecc_info,
575                         unsigned int memtype, u32 flags, char *label)
576 {
577         struct persistent_ram_zone *prz;
578         int ret = -ENOMEM;
579 
580         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
581         if (!prz) {
582                 pr_err("failed to allocate persistent ram zone\n");
583                 goto err;
584         }
585 
586         /* Initialize general buffer state. */
587         raw_spin_lock_init(&prz->buffer_lock);
588         prz->flags = flags;
589         prz->label = kstrdup(label, GFP_KERNEL);
590 
591         ret = persistent_ram_buffer_map(start, size, prz, memtype);
592         if (ret)
593                 goto err;
594 
595         ret = persistent_ram_post_init(prz, sig, ecc_info);
596         if (ret)
597                 goto err;
598 
599         pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
600                 prz->label, prz->size, (unsigned long long)prz->paddr,
601                 sizeof(*prz->buffer), prz->buffer_size,
602                 prz->size - sizeof(*prz->buffer) - prz->buffer_size,
603                 prz->ecc_info.ecc_size, prz->ecc_info.block_size);
604 
605         return prz;
606 err:
607         persistent_ram_free(prz);
608         return ERR_PTR(ret);
609 }
610 

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