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1/*
2 * Persistent Storage - platform driver interface parts.
3 *
4 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19
20#include <linux/atomic.h>
21#include <linux/types.h>
22#include <linux/errno.h>
23#include <linux/init.h>
24#include <linux/kmsg_dump.h>
25#include <linux/module.h>
26#include <linux/pstore.h>
27#include <linux/string.h>
28#include <linux/slab.h>
29#include <linux/uaccess.h>
30
31#include "internal.h"
32
33/*
34 * pstore_lock just protects "psinfo" during
35 * calls to pstore_register()
36 */
37static DEFINE_SPINLOCK(pstore_lock);
38static struct pstore_info *psinfo;
39
40static char *backend;
41
42/* How much of the console log to snapshot */
43static unsigned long kmsg_bytes = 10240;
44
45void pstore_set_kmsg_bytes(int bytes)
46{
47 kmsg_bytes = bytes;
48}
49
50/* Tag each group of saved records with a sequence number */
51static int oopscount;
52
53static char *reason_str[] = {
54 "Oops", "Panic", "Kexec", "Restart", "Halt", "Poweroff", "Emergency"
55};
56
57/*
58 * callback from kmsg_dump. (s2,l2) has the most recently
59 * written bytes, older bytes are in (s1,l1). Save as much
60 * as we can from the end of the buffer.
61 */
62static void pstore_dump(struct kmsg_dumper *dumper,
63 enum kmsg_dump_reason reason,
64 const char *s1, unsigned long l1,
65 const char *s2, unsigned long l2)
66{
67 unsigned long s1_start, s2_start;
68 unsigned long l1_cpy, l2_cpy;
69 unsigned long size, total = 0;
70 char *dst, *why;
71 u64 id;
72 int hsize;
73 unsigned int part = 1;
74
75 if (reason < ARRAY_SIZE(reason_str))
76 why = reason_str[reason];
77 else
78 why = "Unknown";
79
80 mutex_lock(&psinfo->buf_mutex);
81 oopscount++;
82 while (total < kmsg_bytes) {
83 dst = psinfo->buf;
84 hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount, part);
85 size = psinfo->bufsize - hsize;
86 dst += hsize;
87
88 l2_cpy = min(l2, size);
89 l1_cpy = min(l1, size - l2_cpy);
90
91 if (l1_cpy + l2_cpy == 0)
92 break;
93
94 s2_start = l2 - l2_cpy;
95 s1_start = l1 - l1_cpy;
96
97 memcpy(dst, s1 + s1_start, l1_cpy);
98 memcpy(dst + l1_cpy, s2 + s2_start, l2_cpy);
99
100 id = psinfo->write(PSTORE_TYPE_DMESG, part,
101 hsize + l1_cpy + l2_cpy, psinfo);
102 if (reason == KMSG_DUMP_OOPS && pstore_is_mounted())
103 pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id,
104 psinfo->buf, hsize + l1_cpy + l2_cpy,
105 CURRENT_TIME, psinfo);
106 l1 -= l1_cpy;
107 l2 -= l2_cpy;
108 total += l1_cpy + l2_cpy;
109 part++;
110 }
111 mutex_unlock(&psinfo->buf_mutex);
112}
113
114static struct kmsg_dumper pstore_dumper = {
115 .dump = pstore_dump,
116};
117
118/*
119 * platform specific persistent storage driver registers with
120 * us here. If pstore is already mounted, call the platform
121 * read function right away to populate the file system. If not
122 * then the pstore mount code will call us later to fill out
123 * the file system.
124 *
125 * Register with kmsg_dump to save last part of console log on panic.
126 */
127int pstore_register(struct pstore_info *psi)
128{
129 struct module *owner = psi->owner;
130
131 spin_lock(&pstore_lock);
132 if (psinfo) {
133 spin_unlock(&pstore_lock);
134 return -EBUSY;
135 }
136
137 if (backend && strcmp(backend, psi->name)) {
138 spin_unlock(&pstore_lock);
139 return -EINVAL;
140 }
141
142 psinfo = psi;
143 spin_unlock(&pstore_lock);
144
145 if (owner && !try_module_get(owner)) {
146 psinfo = NULL;
147 return -EINVAL;
148 }
149
150 if (pstore_is_mounted())
151 pstore_get_records();
152
153 kmsg_dump_register(&pstore_dumper);
154
155 return 0;
156}
157EXPORT_SYMBOL_GPL(pstore_register);
158
159/*
160 * Read all the records from the persistent store. Create and
161 * file files in our filesystem.
162 */
163void pstore_get_records(void)
164{
165 struct pstore_info *psi = psinfo;
166 ssize_t size;
167 u64 id;
168 enum pstore_type_id type;
169 struct timespec time;
170 int failed = 0, rc;
171
172 if (!psi)
173 return;
174
175 mutex_lock(&psinfo->buf_mutex);
176 rc = psi->open(psi);
177 if (rc)
178 goto out;
179
180 while ((size = psi->read(&id, &type, &time, psi)) > 0) {
181 if (pstore_mkfile(type, psi->name, id, psi->buf, (size_t)size,
182 time, psi))
183 failed++;
184 }
185 psi->close(psi);
186out:
187 mutex_unlock(&psinfo->buf_mutex);
188
189 if (failed)
190 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
191 failed, psi->name);
192}
193
194/*
195 * Call platform driver to write a record to the
196 * persistent store.
197 */
198int pstore_write(enum pstore_type_id type, char *buf, size_t size)
199{
200 u64 id;
201
202 if (!psinfo)
203 return -ENODEV;
204
205 if (size > psinfo->bufsize)
206 return -EFBIG;
207
208 mutex_lock(&psinfo->buf_mutex);
209 memcpy(psinfo->buf, buf, size);
210 id = psinfo->write(type, 0, size, psinfo);
211 if (pstore_is_mounted())
212 pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, psinfo->buf,
213 size, CURRENT_TIME, psinfo);
214 mutex_unlock(&psinfo->buf_mutex);
215
216 return 0;
217}
218EXPORT_SYMBOL_GPL(pstore_write);
219
220module_param(backend, charp, 0444);
221MODULE_PARM_DESC(backend, "Pstore backend to use");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Persistent Storage - platform driver interface parts.
4 *
5 * Copyright (C) 2007-2008 Google, Inc.
6 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
7 */
8
9#define pr_fmt(fmt) "pstore: " fmt
10
11#include <linux/atomic.h>
12#include <linux/types.h>
13#include <linux/errno.h>
14#include <linux/init.h>
15#include <linux/kmsg_dump.h>
16#include <linux/console.h>
17#include <linux/module.h>
18#include <linux/pstore.h>
19#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
20#include <linux/lzo.h>
21#endif
22#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
23#include <linux/lz4.h>
24#endif
25#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
26#include <linux/zstd.h>
27#endif
28#include <linux/crypto.h>
29#include <linux/string.h>
30#include <linux/timer.h>
31#include <linux/slab.h>
32#include <linux/uaccess.h>
33#include <linux/jiffies.h>
34#include <linux/workqueue.h>
35
36#include "internal.h"
37
38/*
39 * We defer making "oops" entries appear in pstore - see
40 * whether the system is actually still running well enough
41 * to let someone see the entry
42 */
43static int pstore_update_ms = -1;
44module_param_named(update_ms, pstore_update_ms, int, 0600);
45MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
46 "(default is -1, which means runtime updates are disabled; "
47 "enabling this option may not be safe; it may lead to further "
48 "corruption on Oopses)");
49
50/* Names should be in the same order as the enum pstore_type_id */
51static const char * const pstore_type_names[] = {
52 "dmesg",
53 "mce",
54 "console",
55 "ftrace",
56 "rtas",
57 "powerpc-ofw",
58 "powerpc-common",
59 "pmsg",
60 "powerpc-opal",
61};
62
63static int pstore_new_entry;
64
65static void pstore_timefunc(struct timer_list *);
66static DEFINE_TIMER(pstore_timer, pstore_timefunc);
67
68static void pstore_dowork(struct work_struct *);
69static DECLARE_WORK(pstore_work, pstore_dowork);
70
71/*
72 * psinfo_lock protects "psinfo" during calls to
73 * pstore_register(), pstore_unregister(), and
74 * the filesystem mount/unmount routines.
75 */
76static DEFINE_MUTEX(psinfo_lock);
77struct pstore_info *psinfo;
78
79static char *backend;
80module_param(backend, charp, 0444);
81MODULE_PARM_DESC(backend, "specific backend to use");
82
83static char *compress =
84#ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
85 CONFIG_PSTORE_COMPRESS_DEFAULT;
86#else
87 NULL;
88#endif
89module_param(compress, charp, 0444);
90MODULE_PARM_DESC(compress, "compression to use");
91
92/* Compression parameters */
93static struct crypto_comp *tfm;
94
95struct pstore_zbackend {
96 int (*zbufsize)(size_t size);
97 const char *name;
98};
99
100static char *big_oops_buf;
101static size_t big_oops_buf_sz;
102
103/* How much of the console log to snapshot */
104unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
105
106void pstore_set_kmsg_bytes(int bytes)
107{
108 kmsg_bytes = bytes;
109}
110
111/* Tag each group of saved records with a sequence number */
112static int oopscount;
113
114const char *pstore_type_to_name(enum pstore_type_id type)
115{
116 BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
117
118 if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
119 return "unknown";
120
121 return pstore_type_names[type];
122}
123EXPORT_SYMBOL_GPL(pstore_type_to_name);
124
125enum pstore_type_id pstore_name_to_type(const char *name)
126{
127 int i;
128
129 for (i = 0; i < PSTORE_TYPE_MAX; i++) {
130 if (!strcmp(pstore_type_names[i], name))
131 return i;
132 }
133
134 return PSTORE_TYPE_MAX;
135}
136EXPORT_SYMBOL_GPL(pstore_name_to_type);
137
138static void pstore_timer_kick(void)
139{
140 if (pstore_update_ms < 0)
141 return;
142
143 mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
144}
145
146/*
147 * Should pstore_dump() wait for a concurrent pstore_dump()? If
148 * not, the current pstore_dump() will report a failure to dump
149 * and return.
150 */
151static bool pstore_cannot_wait(enum kmsg_dump_reason reason)
152{
153 /* In NMI path, pstore shouldn't block regardless of reason. */
154 if (in_nmi())
155 return true;
156
157 switch (reason) {
158 /* In panic case, other cpus are stopped by smp_send_stop(). */
159 case KMSG_DUMP_PANIC:
160 /* Emergency restart shouldn't be blocked. */
161 case KMSG_DUMP_EMERG:
162 return true;
163 default:
164 return false;
165 }
166}
167
168#if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
169static int zbufsize_deflate(size_t size)
170{
171 size_t cmpr;
172
173 switch (size) {
174 /* buffer range for efivars */
175 case 1000 ... 2000:
176 cmpr = 56;
177 break;
178 case 2001 ... 3000:
179 cmpr = 54;
180 break;
181 case 3001 ... 3999:
182 cmpr = 52;
183 break;
184 /* buffer range for nvram, erst */
185 case 4000 ... 10000:
186 cmpr = 45;
187 break;
188 default:
189 cmpr = 60;
190 break;
191 }
192
193 return (size * 100) / cmpr;
194}
195#endif
196
197#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
198static int zbufsize_lzo(size_t size)
199{
200 return lzo1x_worst_compress(size);
201}
202#endif
203
204#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
205static int zbufsize_lz4(size_t size)
206{
207 return LZ4_compressBound(size);
208}
209#endif
210
211#if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
212static int zbufsize_842(size_t size)
213{
214 return size;
215}
216#endif
217
218#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
219static int zbufsize_zstd(size_t size)
220{
221 return ZSTD_compressBound(size);
222}
223#endif
224
225static const struct pstore_zbackend *zbackend __ro_after_init;
226
227static const struct pstore_zbackend zbackends[] = {
228#if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
229 {
230 .zbufsize = zbufsize_deflate,
231 .name = "deflate",
232 },
233#endif
234#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
235 {
236 .zbufsize = zbufsize_lzo,
237 .name = "lzo",
238 },
239#endif
240#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
241 {
242 .zbufsize = zbufsize_lz4,
243 .name = "lz4",
244 },
245#endif
246#if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
247 {
248 .zbufsize = zbufsize_lz4,
249 .name = "lz4hc",
250 },
251#endif
252#if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
253 {
254 .zbufsize = zbufsize_842,
255 .name = "842",
256 },
257#endif
258#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
259 {
260 .zbufsize = zbufsize_zstd,
261 .name = "zstd",
262 },
263#endif
264 { }
265};
266
267static int pstore_compress(const void *in, void *out,
268 unsigned int inlen, unsigned int outlen)
269{
270 int ret;
271
272 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
273 return -EINVAL;
274
275 ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
276 if (ret) {
277 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
278 return ret;
279 }
280
281 return outlen;
282}
283
284static void allocate_buf_for_compression(void)
285{
286 struct crypto_comp *ctx;
287 int size;
288 char *buf;
289
290 /* Skip if not built-in or compression backend not selected yet. */
291 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
292 return;
293
294 /* Skip if no pstore backend yet or compression init already done. */
295 if (!psinfo || tfm)
296 return;
297
298 if (!crypto_has_comp(zbackend->name, 0, 0)) {
299 pr_err("Unknown compression: %s\n", zbackend->name);
300 return;
301 }
302
303 size = zbackend->zbufsize(psinfo->bufsize);
304 if (size <= 0) {
305 pr_err("Invalid compression size for %s: %d\n",
306 zbackend->name, size);
307 return;
308 }
309
310 buf = kmalloc(size, GFP_KERNEL);
311 if (!buf) {
312 pr_err("Failed %d byte compression buffer allocation for: %s\n",
313 size, zbackend->name);
314 return;
315 }
316
317 ctx = crypto_alloc_comp(zbackend->name, 0, 0);
318 if (IS_ERR_OR_NULL(ctx)) {
319 kfree(buf);
320 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
321 PTR_ERR(ctx));
322 return;
323 }
324
325 /* A non-NULL big_oops_buf indicates compression is available. */
326 tfm = ctx;
327 big_oops_buf_sz = size;
328 big_oops_buf = buf;
329
330 pr_info("Using crash dump compression: %s\n", zbackend->name);
331}
332
333static void free_buf_for_compression(void)
334{
335 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
336 crypto_free_comp(tfm);
337 tfm = NULL;
338 }
339 kfree(big_oops_buf);
340 big_oops_buf = NULL;
341 big_oops_buf_sz = 0;
342}
343
344/*
345 * Called when compression fails, since the printk buffer
346 * would be fetched for compression calling it again when
347 * compression fails would have moved the iterator of
348 * printk buffer which results in fetching old contents.
349 * Copy the recent messages from big_oops_buf to psinfo->buf
350 */
351static size_t copy_kmsg_to_buffer(int hsize, size_t len)
352{
353 size_t total_len;
354 size_t diff;
355
356 total_len = hsize + len;
357
358 if (total_len > psinfo->bufsize) {
359 diff = total_len - psinfo->bufsize + hsize;
360 memcpy(psinfo->buf, big_oops_buf, hsize);
361 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
362 psinfo->bufsize - hsize);
363 total_len = psinfo->bufsize;
364 } else
365 memcpy(psinfo->buf, big_oops_buf, total_len);
366
367 return total_len;
368}
369
370void pstore_record_init(struct pstore_record *record,
371 struct pstore_info *psinfo)
372{
373 memset(record, 0, sizeof(*record));
374
375 record->psi = psinfo;
376
377 /* Report zeroed timestamp if called before timekeeping has resumed. */
378 record->time = ns_to_timespec64(ktime_get_real_fast_ns());
379}
380
381/*
382 * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
383 * end of the buffer.
384 */
385static void pstore_dump(struct kmsg_dumper *dumper,
386 enum kmsg_dump_reason reason)
387{
388 struct kmsg_dump_iter iter;
389 unsigned long total = 0;
390 const char *why;
391 unsigned int part = 1;
392 int ret;
393
394 why = kmsg_dump_reason_str(reason);
395
396 if (down_trylock(&psinfo->buf_lock)) {
397 /* Failed to acquire lock: give up if we cannot wait. */
398 if (pstore_cannot_wait(reason)) {
399 pr_err("dump skipped in %s path: may corrupt error record\n",
400 in_nmi() ? "NMI" : why);
401 return;
402 }
403 if (down_interruptible(&psinfo->buf_lock)) {
404 pr_err("could not grab semaphore?!\n");
405 return;
406 }
407 }
408
409 kmsg_dump_rewind(&iter);
410
411 oopscount++;
412 while (total < kmsg_bytes) {
413 char *dst;
414 size_t dst_size;
415 int header_size;
416 int zipped_len = -1;
417 size_t dump_size;
418 struct pstore_record record;
419
420 pstore_record_init(&record, psinfo);
421 record.type = PSTORE_TYPE_DMESG;
422 record.count = oopscount;
423 record.reason = reason;
424 record.part = part;
425 record.buf = psinfo->buf;
426
427 if (big_oops_buf) {
428 dst = big_oops_buf;
429 dst_size = big_oops_buf_sz;
430 } else {
431 dst = psinfo->buf;
432 dst_size = psinfo->bufsize;
433 }
434
435 /* Write dump header. */
436 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
437 oopscount, part);
438 dst_size -= header_size;
439
440 /* Write dump contents. */
441 if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,
442 dst_size, &dump_size))
443 break;
444
445 if (big_oops_buf) {
446 zipped_len = pstore_compress(dst, psinfo->buf,
447 header_size + dump_size,
448 psinfo->bufsize);
449
450 if (zipped_len > 0) {
451 record.compressed = true;
452 record.size = zipped_len;
453 } else {
454 record.size = copy_kmsg_to_buffer(header_size,
455 dump_size);
456 }
457 } else {
458 record.size = header_size + dump_size;
459 }
460
461 ret = psinfo->write(&record);
462 if (ret == 0 && reason == KMSG_DUMP_OOPS) {
463 pstore_new_entry = 1;
464 pstore_timer_kick();
465 }
466
467 total += record.size;
468 part++;
469 }
470
471 up(&psinfo->buf_lock);
472}
473
474static struct kmsg_dumper pstore_dumper = {
475 .dump = pstore_dump,
476};
477
478/*
479 * Register with kmsg_dump to save last part of console log on panic.
480 */
481static void pstore_register_kmsg(void)
482{
483 kmsg_dump_register(&pstore_dumper);
484}
485
486static void pstore_unregister_kmsg(void)
487{
488 kmsg_dump_unregister(&pstore_dumper);
489}
490
491#ifdef CONFIG_PSTORE_CONSOLE
492static void pstore_console_write(struct console *con, const char *s, unsigned c)
493{
494 struct pstore_record record;
495
496 if (!c)
497 return;
498
499 pstore_record_init(&record, psinfo);
500 record.type = PSTORE_TYPE_CONSOLE;
501
502 record.buf = (char *)s;
503 record.size = c;
504 psinfo->write(&record);
505}
506
507static struct console pstore_console = {
508 .write = pstore_console_write,
509 .index = -1,
510};
511
512static void pstore_register_console(void)
513{
514 /* Show which backend is going to get console writes. */
515 strscpy(pstore_console.name, psinfo->name,
516 sizeof(pstore_console.name));
517 /*
518 * Always initialize flags here since prior unregister_console()
519 * calls may have changed settings (specifically CON_ENABLED).
520 */
521 pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
522 register_console(&pstore_console);
523}
524
525static void pstore_unregister_console(void)
526{
527 unregister_console(&pstore_console);
528}
529#else
530static void pstore_register_console(void) {}
531static void pstore_unregister_console(void) {}
532#endif
533
534static int pstore_write_user_compat(struct pstore_record *record,
535 const char __user *buf)
536{
537 int ret = 0;
538
539 if (record->buf)
540 return -EINVAL;
541
542 record->buf = memdup_user(buf, record->size);
543 if (IS_ERR(record->buf)) {
544 ret = PTR_ERR(record->buf);
545 goto out;
546 }
547
548 ret = record->psi->write(record);
549
550 kfree(record->buf);
551out:
552 record->buf = NULL;
553
554 return unlikely(ret < 0) ? ret : record->size;
555}
556
557/*
558 * platform specific persistent storage driver registers with
559 * us here. If pstore is already mounted, call the platform
560 * read function right away to populate the file system. If not
561 * then the pstore mount code will call us later to fill out
562 * the file system.
563 */
564int pstore_register(struct pstore_info *psi)
565{
566 if (backend && strcmp(backend, psi->name)) {
567 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
568 return -EPERM;
569 }
570
571 /* Sanity check flags. */
572 if (!psi->flags) {
573 pr_warn("backend '%s' must support at least one frontend\n",
574 psi->name);
575 return -EINVAL;
576 }
577
578 /* Check for required functions. */
579 if (!psi->read || !psi->write) {
580 pr_warn("backend '%s' must implement read() and write()\n",
581 psi->name);
582 return -EINVAL;
583 }
584
585 mutex_lock(&psinfo_lock);
586 if (psinfo) {
587 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
588 psinfo->name, psi->name);
589 mutex_unlock(&psinfo_lock);
590 return -EBUSY;
591 }
592
593 if (!psi->write_user)
594 psi->write_user = pstore_write_user_compat;
595 psinfo = psi;
596 mutex_init(&psinfo->read_mutex);
597 sema_init(&psinfo->buf_lock, 1);
598
599 if (psi->flags & PSTORE_FLAGS_DMESG)
600 allocate_buf_for_compression();
601
602 pstore_get_records(0);
603
604 if (psi->flags & PSTORE_FLAGS_DMESG) {
605 pstore_dumper.max_reason = psinfo->max_reason;
606 pstore_register_kmsg();
607 }
608 if (psi->flags & PSTORE_FLAGS_CONSOLE)
609 pstore_register_console();
610 if (psi->flags & PSTORE_FLAGS_FTRACE)
611 pstore_register_ftrace();
612 if (psi->flags & PSTORE_FLAGS_PMSG)
613 pstore_register_pmsg();
614
615 /* Start watching for new records, if desired. */
616 pstore_timer_kick();
617
618 /*
619 * Update the module parameter backend, so it is visible
620 * through /sys/module/pstore/parameters/backend
621 */
622 backend = kstrdup(psi->name, GFP_KERNEL);
623
624 pr_info("Registered %s as persistent store backend\n", psi->name);
625
626 mutex_unlock(&psinfo_lock);
627 return 0;
628}
629EXPORT_SYMBOL_GPL(pstore_register);
630
631void pstore_unregister(struct pstore_info *psi)
632{
633 /* It's okay to unregister nothing. */
634 if (!psi)
635 return;
636
637 mutex_lock(&psinfo_lock);
638
639 /* Only one backend can be registered at a time. */
640 if (WARN_ON(psi != psinfo)) {
641 mutex_unlock(&psinfo_lock);
642 return;
643 }
644
645 /* Unregister all callbacks. */
646 if (psi->flags & PSTORE_FLAGS_PMSG)
647 pstore_unregister_pmsg();
648 if (psi->flags & PSTORE_FLAGS_FTRACE)
649 pstore_unregister_ftrace();
650 if (psi->flags & PSTORE_FLAGS_CONSOLE)
651 pstore_unregister_console();
652 if (psi->flags & PSTORE_FLAGS_DMESG)
653 pstore_unregister_kmsg();
654
655 /* Stop timer and make sure all work has finished. */
656 del_timer_sync(&pstore_timer);
657 flush_work(&pstore_work);
658
659 /* Remove all backend records from filesystem tree. */
660 pstore_put_backend_records(psi);
661
662 free_buf_for_compression();
663
664 psinfo = NULL;
665 kfree(backend);
666 backend = NULL;
667 mutex_unlock(&psinfo_lock);
668}
669EXPORT_SYMBOL_GPL(pstore_unregister);
670
671static void decompress_record(struct pstore_record *record)
672{
673 int ret;
674 int unzipped_len;
675 char *unzipped, *workspace;
676
677 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
678 return;
679
680 /* Only PSTORE_TYPE_DMESG support compression. */
681 if (record->type != PSTORE_TYPE_DMESG) {
682 pr_warn("ignored compressed record type %d\n", record->type);
683 return;
684 }
685
686 /* Missing compression buffer means compression was not initialized. */
687 if (!big_oops_buf) {
688 pr_warn("no decompression method initialized!\n");
689 return;
690 }
691
692 /* Allocate enough space to hold max decompression and ECC. */
693 unzipped_len = big_oops_buf_sz;
694 workspace = kmalloc(unzipped_len + record->ecc_notice_size,
695 GFP_KERNEL);
696 if (!workspace)
697 return;
698
699 /* After decompression "unzipped_len" is almost certainly smaller. */
700 ret = crypto_comp_decompress(tfm, record->buf, record->size,
701 workspace, &unzipped_len);
702 if (ret) {
703 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
704 kfree(workspace);
705 return;
706 }
707
708 /* Append ECC notice to decompressed buffer. */
709 memcpy(workspace + unzipped_len, record->buf + record->size,
710 record->ecc_notice_size);
711
712 /* Copy decompressed contents into an minimum-sized allocation. */
713 unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
714 GFP_KERNEL);
715 kfree(workspace);
716 if (!unzipped)
717 return;
718
719 /* Swap out compressed contents with decompressed contents. */
720 kfree(record->buf);
721 record->buf = unzipped;
722 record->size = unzipped_len;
723 record->compressed = false;
724}
725
726/*
727 * Read all the records from one persistent store backend. Create
728 * files in our filesystem. Don't warn about -EEXIST errors
729 * when we are re-scanning the backing store looking to add new
730 * error records.
731 */
732void pstore_get_backend_records(struct pstore_info *psi,
733 struct dentry *root, int quiet)
734{
735 int failed = 0;
736 unsigned int stop_loop = 65536;
737
738 if (!psi || !root)
739 return;
740
741 mutex_lock(&psi->read_mutex);
742 if (psi->open && psi->open(psi))
743 goto out;
744
745 /*
746 * Backend callback read() allocates record.buf. decompress_record()
747 * may reallocate record.buf. On success, pstore_mkfile() will keep
748 * the record.buf, so free it only on failure.
749 */
750 for (; stop_loop; stop_loop--) {
751 struct pstore_record *record;
752 int rc;
753
754 record = kzalloc(sizeof(*record), GFP_KERNEL);
755 if (!record) {
756 pr_err("out of memory creating record\n");
757 break;
758 }
759 pstore_record_init(record, psi);
760
761 record->size = psi->read(record);
762
763 /* No more records left in backend? */
764 if (record->size <= 0) {
765 kfree(record);
766 break;
767 }
768
769 decompress_record(record);
770 rc = pstore_mkfile(root, record);
771 if (rc) {
772 /* pstore_mkfile() did not take record, so free it. */
773 kfree(record->buf);
774 kfree(record);
775 if (rc != -EEXIST || !quiet)
776 failed++;
777 }
778 }
779 if (psi->close)
780 psi->close(psi);
781out:
782 mutex_unlock(&psi->read_mutex);
783
784 if (failed)
785 pr_warn("failed to create %d record(s) from '%s'\n",
786 failed, psi->name);
787 if (!stop_loop)
788 pr_err("looping? Too many records seen from '%s'\n",
789 psi->name);
790}
791
792static void pstore_dowork(struct work_struct *work)
793{
794 pstore_get_records(1);
795}
796
797static void pstore_timefunc(struct timer_list *unused)
798{
799 if (pstore_new_entry) {
800 pstore_new_entry = 0;
801 schedule_work(&pstore_work);
802 }
803
804 pstore_timer_kick();
805}
806
807static void __init pstore_choose_compression(void)
808{
809 const struct pstore_zbackend *step;
810
811 if (!compress)
812 return;
813
814 for (step = zbackends; step->name; step++) {
815 if (!strcmp(compress, step->name)) {
816 zbackend = step;
817 return;
818 }
819 }
820}
821
822static int __init pstore_init(void)
823{
824 int ret;
825
826 pstore_choose_compression();
827
828 /*
829 * Check if any pstore backends registered earlier but did not
830 * initialize compression because crypto was not ready. If so,
831 * initialize compression now.
832 */
833 allocate_buf_for_compression();
834
835 ret = pstore_init_fs();
836 if (ret)
837 free_buf_for_compression();
838
839 return ret;
840}
841late_initcall(pstore_init);
842
843static void __exit pstore_exit(void)
844{
845 pstore_exit_fs();
846}
847module_exit(pstore_exit)
848
849MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
850MODULE_LICENSE("GPL");