1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2012 Google, Inc.
6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8 #include <linux/device.h>
10 #include <linux/errno.h>
11 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/list.h>
15 #include <linux/memblock.h>
16 #include <linux/rslib.h>
17 #include <linux/slab.h>
18 #include <linux/uaccess.h>
19 #include <linux/vmalloc.h>
22 #include "ram_internal.h"
25 * struct persistent_ram_buffer - persistent circular RAM buffer
28 * signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
30 * offset into @data where the beginning of the stored bytes begin
32 * number of valid bytes stored in @data
34 struct persistent_ram_buffer {
41 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
43 static inline size_t buffer_size(struct persistent_ram_zone *prz)
45 return atomic_read(&prz->buffer->size);
48 static inline size_t buffer_start(struct persistent_ram_zone *prz)
50 return atomic_read(&prz->buffer->start);
53 /* increase and wrap the start pointer, returning the old value */
54 static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
58 unsigned long flags = 0;
60 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
61 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
63 old = atomic_read(&prz->buffer->start);
65 while (unlikely(new >= prz->buffer_size))
66 new -= prz->buffer_size;
67 atomic_set(&prz->buffer->start, new);
69 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
70 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
75 /* increase the size counter until it hits the max size */
76 static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
80 unsigned long flags = 0;
82 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
83 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
85 old = atomic_read(&prz->buffer->size);
86 if (old == prz->buffer_size)
90 if (new > prz->buffer_size)
91 new = prz->buffer_size;
92 atomic_set(&prz->buffer->size, new);
95 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
96 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
99 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
100 uint8_t *data, size_t len, uint8_t *ecc)
104 /* Initialize the parity buffer */
105 memset(prz->ecc_info.par, 0,
106 prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));
107 encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);
108 for (i = 0; i < prz->ecc_info.ecc_size; i++)
109 ecc[i] = prz->ecc_info.par[i];
112 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
113 void *data, size_t len, uint8_t *ecc)
117 for (i = 0; i < prz->ecc_info.ecc_size; i++)
118 prz->ecc_info.par[i] = ecc[i];
119 return decode_rs8(prz->rs_decoder, data, prz->ecc_info.par, len,
120 NULL, 0, NULL, 0, NULL);
123 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
124 unsigned int start, unsigned int count)
126 struct persistent_ram_buffer *buffer = prz->buffer;
127 uint8_t *buffer_end = buffer->data + prz->buffer_size;
130 int ecc_block_size = prz->ecc_info.block_size;
131 int ecc_size = prz->ecc_info.ecc_size;
132 int size = ecc_block_size;
137 block = buffer->data + (start & ~(ecc_block_size - 1));
138 par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
141 if (block + ecc_block_size > buffer_end)
142 size = buffer_end - block;
143 persistent_ram_encode_rs8(prz, block, size, par);
144 block += ecc_block_size;
146 } while (block < buffer->data + start + count);
149 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
151 struct persistent_ram_buffer *buffer = prz->buffer;
153 if (!prz->ecc_info.ecc_size)
156 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
160 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
162 struct persistent_ram_buffer *buffer = prz->buffer;
166 if (!prz->ecc_info.ecc_size)
169 block = buffer->data;
170 par = prz->par_buffer;
171 while (block < buffer->data + buffer_size(prz)) {
173 int size = prz->ecc_info.block_size;
174 if (block + size > buffer->data + prz->buffer_size)
175 size = buffer->data + prz->buffer_size - block;
176 numerr = persistent_ram_decode_rs8(prz, block, size, par);
178 pr_devel("error in block %p, %d\n", block, numerr);
179 prz->corrected_bytes += numerr;
180 } else if (numerr < 0) {
181 pr_devel("uncorrectable error in block %p\n", block);
184 block += prz->ecc_info.block_size;
185 par += prz->ecc_info.ecc_size;
189 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
190 struct persistent_ram_ecc_info *ecc_info)
193 struct persistent_ram_buffer *buffer = prz->buffer;
197 if (!ecc_info || !ecc_info->ecc_size)
200 prz->ecc_info.block_size = ecc_info->block_size ?: 128;
201 prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
202 prz->ecc_info.symsize = ecc_info->symsize ?: 8;
203 prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
205 ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
206 prz->ecc_info.block_size +
207 prz->ecc_info.ecc_size);
208 ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
209 if (ecc_total >= prz->buffer_size) {
210 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
211 __func__, prz->ecc_info.ecc_size,
212 ecc_total, prz->buffer_size);
216 prz->buffer_size -= ecc_total;
217 prz->par_buffer = buffer->data + prz->buffer_size;
218 prz->par_header = prz->par_buffer +
219 ecc_blocks * prz->ecc_info.ecc_size;
222 * first consecutive root is 0
223 * primitive element to generate roots = 1
225 prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
226 0, 1, prz->ecc_info.ecc_size);
227 if (prz->rs_decoder == NULL) {
228 pr_info("init_rs failed\n");
232 /* allocate workspace instead of using stack VLA */
233 prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,
234 sizeof(*prz->ecc_info.par),
236 if (!prz->ecc_info.par) {
237 pr_err("cannot allocate ECC parity workspace\n");
241 prz->corrected_bytes = 0;
244 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
247 pr_info("error in header, %d\n", numerr);
248 prz->corrected_bytes += numerr;
249 } else if (numerr < 0) {
250 pr_info_ratelimited("uncorrectable error in header\n");
257 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
258 char *str, size_t len)
262 if (!prz->ecc_info.ecc_size)
265 if (prz->corrected_bytes || prz->bad_blocks)
266 ret = snprintf(str, len, ""
267 "\nECC: %d Corrected bytes, %d unrecoverable blocks\n",
268 prz->corrected_bytes, prz->bad_blocks);
270 ret = snprintf(str, len, "\nECC: No errors detected\n");
275 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
276 const void *s, unsigned int start, unsigned int count)
278 struct persistent_ram_buffer *buffer = prz->buffer;
279 memcpy_toio(buffer->data + start, s, count);
280 persistent_ram_update_ecc(prz, start, count);
283 static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
284 const void __user *s, unsigned int start, unsigned int count)
286 struct persistent_ram_buffer *buffer = prz->buffer;
287 int ret = unlikely(copy_from_user(buffer->data + start, s, count)) ?
289 persistent_ram_update_ecc(prz, start, count);
293 void persistent_ram_save_old(struct persistent_ram_zone *prz)
295 struct persistent_ram_buffer *buffer = prz->buffer;
296 size_t size = buffer_size(prz);
297 size_t start = buffer_start(prz);
303 persistent_ram_ecc_old(prz);
304 prz->old_log = kmalloc(size, GFP_KERNEL);
307 pr_err("failed to allocate buffer\n");
311 prz->old_log_size = size;
312 memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
313 memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
316 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
317 const void *s, unsigned int count)
323 if (unlikely(c > prz->buffer_size)) {
324 s += c - prz->buffer_size;
325 c = prz->buffer_size;
328 buffer_size_add(prz, c);
330 start = buffer_start_add(prz, c);
332 rem = prz->buffer_size - start;
333 if (unlikely(rem < c)) {
334 persistent_ram_update(prz, s, start, rem);
339 persistent_ram_update(prz, s, start, c);
341 persistent_ram_update_header_ecc(prz);
346 int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
347 const void __user *s, unsigned int count)
349 int rem, ret = 0, c = count;
352 if (unlikely(c > prz->buffer_size)) {
353 s += c - prz->buffer_size;
354 c = prz->buffer_size;
357 buffer_size_add(prz, c);
359 start = buffer_start_add(prz, c);
361 rem = prz->buffer_size - start;
362 if (unlikely(rem < c)) {
363 ret = persistent_ram_update_user(prz, s, start, rem);
369 ret = persistent_ram_update_user(prz, s, start, c);
371 persistent_ram_update_header_ecc(prz);
373 return unlikely(ret) ? ret : count;
376 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
378 return prz->old_log_size;
381 void *persistent_ram_old(struct persistent_ram_zone *prz)
386 void persistent_ram_free_old(struct persistent_ram_zone *prz)
390 prz->old_log_size = 0;
393 void persistent_ram_zap(struct persistent_ram_zone *prz)
395 atomic_set(&prz->buffer->start, 0);
396 atomic_set(&prz->buffer->size, 0);
397 persistent_ram_update_header_ecc(prz);
400 #define MEM_TYPE_WCOMBINE 0
401 #define MEM_TYPE_NONCACHED 1
402 #define MEM_TYPE_NORMAL 2
404 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
405 unsigned int memtype)
408 phys_addr_t page_start;
409 unsigned int page_count;
414 page_start = start - offset_in_page(start);
415 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
418 case MEM_TYPE_NORMAL:
421 case MEM_TYPE_NONCACHED:
422 prot = pgprot_noncached(PAGE_KERNEL);
424 case MEM_TYPE_WCOMBINE:
425 prot = pgprot_writecombine(PAGE_KERNEL);
428 pr_err("invalid mem_type=%d\n", memtype);
432 pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
434 pr_err("%s: Failed to allocate array for %u pages\n",
435 __func__, page_count);
439 for (i = 0; i < page_count; i++) {
440 phys_addr_t addr = page_start + i * PAGE_SIZE;
441 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
444 * VM_IOREMAP used here to bypass this region during vread()
445 * and kmap_atomic() (i.e. kcore) to avoid __va() failures.
447 vaddr = vmap(pages, page_count, VM_MAP | VM_IOREMAP, prot);
451 * Since vmap() uses page granularity, we must add the offset
452 * into the page here, to get the byte granularity address
453 * into the mapping to represent the actual "start" location.
455 return vaddr + offset_in_page(start);
458 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
459 unsigned int memtype, char *label)
463 if (!request_mem_region(start, size, label ?: "ramoops")) {
464 pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
466 (unsigned long long)size, (unsigned long long)start);
471 va = ioremap(start, size);
473 va = ioremap_wc(start, size);
476 * Since request_mem_region() and ioremap() are byte-granularity
477 * there is no need handle anything special like we do when the
478 * vmap() case in persistent_ram_vmap() above.
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,
496 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
497 (unsigned long long)size, (unsigned long long)start);
501 prz->buffer = prz->vaddr;
502 prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
507 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
508 struct persistent_ram_ecc_info *ecc_info)
511 bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
513 ret = persistent_ram_init_ecc(prz, ecc_info);
515 pr_warn("ECC failed %s\n", prz->label);
519 sig ^= PERSISTENT_RAM_SIG;
521 if (prz->buffer->sig == sig) {
522 if (buffer_size(prz) == 0) {
523 pr_debug("found existing empty buffer\n");
527 if (buffer_size(prz) > prz->buffer_size ||
528 buffer_start(prz) > buffer_size(prz)) {
529 pr_info("found existing invalid buffer, size %zu, start %zu\n",
530 buffer_size(prz), buffer_start(prz));
533 pr_debug("found existing buffer, size %zu, start %zu\n",
534 buffer_size(prz), buffer_start(prz));
535 persistent_ram_save_old(prz);
538 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
540 prz->buffer->sig = sig;
544 /* Reset missing, invalid, or single-use memory area. */
546 persistent_ram_zap(prz);
551 void persistent_ram_free(struct persistent_ram_zone **_prz)
553 struct persistent_ram_zone *prz;
563 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
564 /* We must vunmap() at page-granularity. */
565 vunmap(prz->vaddr - offset_in_page(prz->paddr));
568 release_mem_region(prz->paddr, prz->size);
572 if (prz->rs_decoder) {
573 free_rs(prz->rs_decoder);
574 prz->rs_decoder = NULL;
576 kfree(prz->ecc_info.par);
577 prz->ecc_info.par = NULL;
579 persistent_ram_free_old(prz);
585 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
586 u32 sig, struct persistent_ram_ecc_info *ecc_info,
587 unsigned int memtype, u32 flags, char *label)
589 struct persistent_ram_zone *prz;
592 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
594 pr_err("failed to allocate persistent ram zone\n");
598 /* Initialize general buffer state. */
599 raw_spin_lock_init(&prz->buffer_lock);
601 prz->label = kstrdup(label, GFP_KERNEL);
603 ret = persistent_ram_buffer_map(start, size, prz, memtype);
607 ret = persistent_ram_post_init(prz, sig, ecc_info);
611 pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
612 prz->label, prz->size, (unsigned long long)prz->paddr,
613 sizeof(*prz->buffer), prz->buffer_size,
614 prz->size - sizeof(*prz->buffer) - prz->buffer_size,
615 prz->ecc_info.ecc_size, prz->ecc_info.block_size);
619 persistent_ram_free(&prz);