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/pstore_ram.h>
17 #include <linux/rslib.h>
18 #include <linux/slab.h>
19 #include <linux/uaccess.h>
20 #include <linux/vmalloc.h>
24 * struct persistent_ram_buffer - persistent circular RAM buffer
27 * signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
29 * offset into @data where the beginning of the stored bytes begin
31 * number of valid bytes stored in @data
33 struct persistent_ram_buffer {
40 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
42 static inline size_t buffer_size(struct persistent_ram_zone *prz)
44 return atomic_read(&prz->buffer->size);
47 static inline size_t buffer_start(struct persistent_ram_zone *prz)
49 return atomic_read(&prz->buffer->start);
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)
57 unsigned long flags = 0;
59 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
60 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
62 old = atomic_read(&prz->buffer->start);
64 while (unlikely(new >= prz->buffer_size))
65 new -= prz->buffer_size;
66 atomic_set(&prz->buffer->start, new);
68 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
69 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
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)
79 unsigned long flags = 0;
81 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
82 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
84 old = atomic_read(&prz->buffer->size);
85 if (old == prz->buffer_size)
89 if (new > prz->buffer_size)
90 new = prz->buffer_size;
91 atomic_set(&prz->buffer->size, new);
94 if (!(prz->flags & PRZ_FLAG_NO_LOCK))
95 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
98 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
99 uint8_t *data, size_t len, uint8_t *ecc)
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];
111 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
112 void *data, size_t len, uint8_t *ecc)
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);
122 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
123 unsigned int start, unsigned int count)
125 struct persistent_ram_buffer *buffer = prz->buffer;
126 uint8_t *buffer_end = buffer->data + prz->buffer_size;
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;
136 block = buffer->data + (start & ~(ecc_block_size - 1));
137 par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
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;
145 } while (block < buffer->data + start + count);
148 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
150 struct persistent_ram_buffer *buffer = prz->buffer;
152 if (!prz->ecc_info.ecc_size)
155 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
159 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
161 struct persistent_ram_buffer *buffer = prz->buffer;
165 if (!prz->ecc_info.ecc_size)
168 block = buffer->data;
169 par = prz->par_buffer;
170 while (block < buffer->data + buffer_size(prz)) {
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);
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);
183 block += prz->ecc_info.block_size;
184 par += prz->ecc_info.ecc_size;
188 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
189 struct persistent_ram_ecc_info *ecc_info)
192 struct persistent_ram_buffer *buffer = prz->buffer;
196 if (!ecc_info || !ecc_info->ecc_size)
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;
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);
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;
221 * first consecutive root is 0
222 * primitive element to generate roots = 1
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");
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),
235 if (!prz->ecc_info.par) {
236 pr_err("cannot allocate ECC parity workspace\n");
240 prz->corrected_bytes = 0;
243 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
246 pr_info("error in header, %d\n", numerr);
247 prz->corrected_bytes += numerr;
248 } else if (numerr < 0) {
249 pr_info("uncorrectable error in header\n");
256 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
257 char *str, size_t len)
261 if (!prz->ecc_info.ecc_size)
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);
269 ret = snprintf(str, len, "\nNo errors detected\n");
274 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
275 const void *s, unsigned int start, unsigned int count)
277 struct persistent_ram_buffer *buffer = prz->buffer;
278 memcpy_toio(buffer->data + start, s, count);
279 persistent_ram_update_ecc(prz, start, count);
282 static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
283 const void __user *s, unsigned int start, unsigned int count)
285 struct persistent_ram_buffer *buffer = prz->buffer;
286 int ret = unlikely(copy_from_user(buffer->data + start, s, count)) ?
288 persistent_ram_update_ecc(prz, start, count);
292 void persistent_ram_save_old(struct persistent_ram_zone *prz)
294 struct persistent_ram_buffer *buffer = prz->buffer;
295 size_t size = buffer_size(prz);
296 size_t start = buffer_start(prz);
302 persistent_ram_ecc_old(prz);
303 prz->old_log = kmalloc(size, GFP_KERNEL);
306 pr_err("failed to allocate buffer\n");
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);
315 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
316 const void *s, unsigned int count)
322 if (unlikely(c > prz->buffer_size)) {
323 s += c - prz->buffer_size;
324 c = prz->buffer_size;
327 buffer_size_add(prz, c);
329 start = buffer_start_add(prz, c);
331 rem = prz->buffer_size - start;
332 if (unlikely(rem < c)) {
333 persistent_ram_update(prz, s, start, rem);
338 persistent_ram_update(prz, s, start, c);
340 persistent_ram_update_header_ecc(prz);
345 int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
346 const void __user *s, unsigned int count)
348 int rem, ret = 0, c = count;
351 if (unlikely(c > prz->buffer_size)) {
352 s += c - prz->buffer_size;
353 c = prz->buffer_size;
356 buffer_size_add(prz, c);
358 start = buffer_start_add(prz, c);
360 rem = prz->buffer_size - start;
361 if (unlikely(rem < c)) {
362 ret = persistent_ram_update_user(prz, s, start, rem);
368 ret = persistent_ram_update_user(prz, s, start, c);
370 persistent_ram_update_header_ecc(prz);
372 return unlikely(ret) ? ret : count;
375 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
377 return prz->old_log_size;
380 void *persistent_ram_old(struct persistent_ram_zone *prz)
385 void persistent_ram_free_old(struct persistent_ram_zone *prz)
389 prz->old_log_size = 0;
392 void persistent_ram_zap(struct persistent_ram_zone *prz)
394 atomic_set(&prz->buffer->start, 0);
395 atomic_set(&prz->buffer->size, 0);
396 persistent_ram_update_header_ecc(prz);
399 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
400 unsigned int memtype)
403 phys_addr_t page_start;
404 unsigned int page_count;
409 page_start = start - offset_in_page(start);
410 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
413 prot = pgprot_noncached(PAGE_KERNEL);
415 prot = pgprot_writecombine(PAGE_KERNEL);
417 pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
419 pr_err("%s: Failed to allocate array for %u pages\n",
420 __func__, page_count);
424 for (i = 0; i < page_count; i++) {
425 phys_addr_t addr = page_start + i * PAGE_SIZE;
426 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
429 * VM_IOREMAP used here to bypass this region during vread()
430 * and kmap_atomic() (i.e. kcore) to avoid __va() failures.
432 vaddr = vmap(pages, page_count, VM_MAP | VM_IOREMAP, prot);
436 * Since vmap() uses page granularity, we must add the offset
437 * into the page here, to get the byte granularity address
438 * into the mapping to represent the actual "start" location.
440 return vaddr + offset_in_page(start);
443 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
444 unsigned int memtype, char *label)
448 if (!request_mem_region(start, size, label ?: "ramoops")) {
449 pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
451 (unsigned long long)size, (unsigned long long)start);
456 va = ioremap(start, size);
458 va = ioremap_wc(start, size);
461 * Since request_mem_region() and ioremap() are byte-granularity
462 * there is no need handle anything special like we do when the
463 * vmap() case in persistent_ram_vmap() above.
468 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
469 struct persistent_ram_zone *prz, int memtype)
474 if (pfn_valid(start >> PAGE_SHIFT))
475 prz->vaddr = persistent_ram_vmap(start, size, memtype);
477 prz->vaddr = persistent_ram_iomap(start, size, memtype,
481 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
482 (unsigned long long)size, (unsigned long long)start);
486 prz->buffer = prz->vaddr;
487 prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
492 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
493 struct persistent_ram_ecc_info *ecc_info)
496 bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
498 ret = persistent_ram_init_ecc(prz, ecc_info);
500 pr_warn("ECC failed %s\n", prz->label);
504 sig ^= PERSISTENT_RAM_SIG;
506 if (prz->buffer->sig == sig) {
507 if (buffer_size(prz) == 0 && buffer_start(prz) == 0) {
508 pr_debug("found existing empty buffer\n");
512 if (buffer_size(prz) > prz->buffer_size ||
513 buffer_start(prz) > buffer_size(prz)) {
514 pr_info("found existing invalid buffer, size %zu, start %zu\n",
515 buffer_size(prz), buffer_start(prz));
518 pr_debug("found existing buffer, size %zu, start %zu\n",
519 buffer_size(prz), buffer_start(prz));
520 persistent_ram_save_old(prz);
523 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
525 prz->buffer->sig = sig;
529 /* Reset missing, invalid, or single-use memory area. */
531 persistent_ram_zap(prz);
536 void persistent_ram_free(struct persistent_ram_zone *prz)
542 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
543 /* We must vunmap() at page-granularity. */
544 vunmap(prz->vaddr - offset_in_page(prz->paddr));
547 release_mem_region(prz->paddr, prz->size);
551 if (prz->rs_decoder) {
552 free_rs(prz->rs_decoder);
553 prz->rs_decoder = NULL;
555 kfree(prz->ecc_info.par);
556 prz->ecc_info.par = NULL;
558 persistent_ram_free_old(prz);
563 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
564 u32 sig, struct persistent_ram_ecc_info *ecc_info,
565 unsigned int memtype, u32 flags, char *label)
567 struct persistent_ram_zone *prz;
570 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
572 pr_err("failed to allocate persistent ram zone\n");
576 /* Initialize general buffer state. */
577 raw_spin_lock_init(&prz->buffer_lock);
579 prz->label = kstrdup(label, GFP_KERNEL);
583 ret = persistent_ram_buffer_map(start, size, prz, memtype);
587 ret = persistent_ram_post_init(prz, sig, ecc_info);
591 pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
592 prz->label, prz->size, (unsigned long long)prz->paddr,
593 sizeof(*prz->buffer), prz->buffer_size,
594 prz->size - sizeof(*prz->buffer) - prz->buffer_size,
595 prz->ecc_info.ecc_size, prz->ecc_info.block_size);
599 persistent_ram_free(prz);