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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 = 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_COMPRESSION))
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 unsigned long total = 0;
389 const char *why;
390 unsigned int part = 1;
391 int ret;
392
393 why = kmsg_dump_reason_str(reason);
394
395 if (down_trylock(&psinfo->buf_lock)) {
396 /* Failed to acquire lock: give up if we cannot wait. */
397 if (pstore_cannot_wait(reason)) {
398 pr_err("dump skipped in %s path: may corrupt error record\n",
399 in_nmi() ? "NMI" : why);
400 return;
401 }
402 if (down_interruptible(&psinfo->buf_lock)) {
403 pr_err("could not grab semaphore?!\n");
404 return;
405 }
406 }
407
408 oopscount++;
409 while (total < kmsg_bytes) {
410 char *dst;
411 size_t dst_size;
412 int header_size;
413 int zipped_len = -1;
414 size_t dump_size;
415 struct pstore_record record;
416
417 pstore_record_init(&record, psinfo);
418 record.type = PSTORE_TYPE_DMESG;
419 record.count = oopscount;
420 record.reason = reason;
421 record.part = part;
422 record.buf = psinfo->buf;
423
424 if (big_oops_buf) {
425 dst = big_oops_buf;
426 dst_size = big_oops_buf_sz;
427 } else {
428 dst = psinfo->buf;
429 dst_size = psinfo->bufsize;
430 }
431
432 /* Write dump header. */
433 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
434 oopscount, part);
435 dst_size -= header_size;
436
437 /* Write dump contents. */
438 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
439 dst_size, &dump_size))
440 break;
441
442 if (big_oops_buf) {
443 zipped_len = pstore_compress(dst, psinfo->buf,
444 header_size + dump_size,
445 psinfo->bufsize);
446
447 if (zipped_len > 0) {
448 record.compressed = true;
449 record.size = zipped_len;
450 } else {
451 record.size = copy_kmsg_to_buffer(header_size,
452 dump_size);
453 }
454 } else {
455 record.size = header_size + dump_size;
456 }
457
458 ret = psinfo->write(&record);
459 if (ret == 0 && reason == KMSG_DUMP_OOPS) {
460 pstore_new_entry = 1;
461 pstore_timer_kick();
462 }
463
464 total += record.size;
465 part++;
466 }
467
468 up(&psinfo->buf_lock);
469}
470
471static struct kmsg_dumper pstore_dumper = {
472 .dump = pstore_dump,
473};
474
475/*
476 * Register with kmsg_dump to save last part of console log on panic.
477 */
478static void pstore_register_kmsg(void)
479{
480 kmsg_dump_register(&pstore_dumper);
481}
482
483static void pstore_unregister_kmsg(void)
484{
485 kmsg_dump_unregister(&pstore_dumper);
486}
487
488#ifdef CONFIG_PSTORE_CONSOLE
489static void pstore_console_write(struct console *con, const char *s, unsigned c)
490{
491 struct pstore_record record;
492
493 if (!c)
494 return;
495
496 pstore_record_init(&record, psinfo);
497 record.type = PSTORE_TYPE_CONSOLE;
498
499 record.buf = (char *)s;
500 record.size = c;
501 psinfo->write(&record);
502}
503
504static struct console pstore_console = {
505 .write = pstore_console_write,
506 .index = -1,
507};
508
509static void pstore_register_console(void)
510{
511 /* Show which backend is going to get console writes. */
512 strscpy(pstore_console.name, psinfo->name,
513 sizeof(pstore_console.name));
514 /*
515 * Always initialize flags here since prior unregister_console()
516 * calls may have changed settings (specifically CON_ENABLED).
517 */
518 pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
519 register_console(&pstore_console);
520}
521
522static void pstore_unregister_console(void)
523{
524 unregister_console(&pstore_console);
525}
526#else
527static void pstore_register_console(void) {}
528static void pstore_unregister_console(void) {}
529#endif
530
531static int pstore_write_user_compat(struct pstore_record *record,
532 const char __user *buf)
533{
534 int ret = 0;
535
536 if (record->buf)
537 return -EINVAL;
538
539 record->buf = memdup_user(buf, record->size);
540 if (IS_ERR(record->buf)) {
541 ret = PTR_ERR(record->buf);
542 goto out;
543 }
544
545 ret = record->psi->write(record);
546
547 kfree(record->buf);
548out:
549 record->buf = NULL;
550
551 return unlikely(ret < 0) ? ret : record->size;
552}
553
554/*
555 * platform specific persistent storage driver registers with
556 * us here. If pstore is already mounted, call the platform
557 * read function right away to populate the file system. If not
558 * then the pstore mount code will call us later to fill out
559 * the file system.
560 */
561int pstore_register(struct pstore_info *psi)
562{
563 if (backend && strcmp(backend, psi->name)) {
564 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
565 return -EPERM;
566 }
567
568 /* Sanity check flags. */
569 if (!psi->flags) {
570 pr_warn("backend '%s' must support at least one frontend\n",
571 psi->name);
572 return -EINVAL;
573 }
574
575 /* Check for required functions. */
576 if (!psi->read || !psi->write) {
577 pr_warn("backend '%s' must implement read() and write()\n",
578 psi->name);
579 return -EINVAL;
580 }
581
582 mutex_lock(&psinfo_lock);
583 if (psinfo) {
584 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
585 psinfo->name, psi->name);
586 mutex_unlock(&psinfo_lock);
587 return -EBUSY;
588 }
589
590 if (!psi->write_user)
591 psi->write_user = pstore_write_user_compat;
592 psinfo = psi;
593 mutex_init(&psinfo->read_mutex);
594 sema_init(&psinfo->buf_lock, 1);
595
596 if (psi->flags & PSTORE_FLAGS_DMESG)
597 allocate_buf_for_compression();
598
599 pstore_get_records(0);
600
601 if (psi->flags & PSTORE_FLAGS_DMESG) {
602 pstore_dumper.max_reason = psinfo->max_reason;
603 pstore_register_kmsg();
604 }
605 if (psi->flags & PSTORE_FLAGS_CONSOLE)
606 pstore_register_console();
607 if (psi->flags & PSTORE_FLAGS_FTRACE)
608 pstore_register_ftrace();
609 if (psi->flags & PSTORE_FLAGS_PMSG)
610 pstore_register_pmsg();
611
612 /* Start watching for new records, if desired. */
613 pstore_timer_kick();
614
615 /*
616 * Update the module parameter backend, so it is visible
617 * through /sys/module/pstore/parameters/backend
618 */
619 backend = kstrdup(psi->name, GFP_KERNEL);
620
621 pr_info("Registered %s as persistent store backend\n", psi->name);
622
623 mutex_unlock(&psinfo_lock);
624 return 0;
625}
626EXPORT_SYMBOL_GPL(pstore_register);
627
628void pstore_unregister(struct pstore_info *psi)
629{
630 /* It's okay to unregister nothing. */
631 if (!psi)
632 return;
633
634 mutex_lock(&psinfo_lock);
635
636 /* Only one backend can be registered at a time. */
637 if (WARN_ON(psi != psinfo)) {
638 mutex_unlock(&psinfo_lock);
639 return;
640 }
641
642 /* Unregister all callbacks. */
643 if (psi->flags & PSTORE_FLAGS_PMSG)
644 pstore_unregister_pmsg();
645 if (psi->flags & PSTORE_FLAGS_FTRACE)
646 pstore_unregister_ftrace();
647 if (psi->flags & PSTORE_FLAGS_CONSOLE)
648 pstore_unregister_console();
649 if (psi->flags & PSTORE_FLAGS_DMESG)
650 pstore_unregister_kmsg();
651
652 /* Stop timer and make sure all work has finished. */
653 del_timer_sync(&pstore_timer);
654 flush_work(&pstore_work);
655
656 /* Remove all backend records from filesystem tree. */
657 pstore_put_backend_records(psi);
658
659 free_buf_for_compression();
660
661 psinfo = NULL;
662 kfree(backend);
663 backend = NULL;
664 mutex_unlock(&psinfo_lock);
665}
666EXPORT_SYMBOL_GPL(pstore_unregister);
667
668static void decompress_record(struct pstore_record *record)
669{
670 int ret;
671 int unzipped_len;
672 char *unzipped, *workspace;
673
674 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESSION) || !record->compressed)
675 return;
676
677 /* Only PSTORE_TYPE_DMESG support compression. */
678 if (record->type != PSTORE_TYPE_DMESG) {
679 pr_warn("ignored compressed record type %d\n", record->type);
680 return;
681 }
682
683 /* Missing compression buffer means compression was not initialized. */
684 if (!big_oops_buf) {
685 pr_warn("no decompression method initialized!\n");
686 return;
687 }
688
689 /* Allocate enough space to hold max decompression and ECC. */
690 unzipped_len = big_oops_buf_sz;
691 workspace = kmalloc(unzipped_len + record->ecc_notice_size,
692 GFP_KERNEL);
693 if (!workspace)
694 return;
695
696 /* After decompression "unzipped_len" is almost certainly smaller. */
697 ret = crypto_comp_decompress(tfm, record->buf, record->size,
698 workspace, &unzipped_len);
699 if (ret) {
700 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
701 kfree(workspace);
702 return;
703 }
704
705 /* Append ECC notice to decompressed buffer. */
706 memcpy(workspace + unzipped_len, record->buf + record->size,
707 record->ecc_notice_size);
708
709 /* Copy decompressed contents into an minimum-sized allocation. */
710 unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
711 GFP_KERNEL);
712 kfree(workspace);
713 if (!unzipped)
714 return;
715
716 /* Swap out compressed contents with decompressed contents. */
717 kfree(record->buf);
718 record->buf = unzipped;
719 record->size = unzipped_len;
720 record->compressed = false;
721}
722
723/*
724 * Read all the records from one persistent store backend. Create
725 * files in our filesystem. Don't warn about -EEXIST errors
726 * when we are re-scanning the backing store looking to add new
727 * error records.
728 */
729void pstore_get_backend_records(struct pstore_info *psi,
730 struct dentry *root, int quiet)
731{
732 int failed = 0;
733 unsigned int stop_loop = 65536;
734
735 if (!psi || !root)
736 return;
737
738 mutex_lock(&psi->read_mutex);
739 if (psi->open && psi->open(psi))
740 goto out;
741
742 /*
743 * Backend callback read() allocates record.buf. decompress_record()
744 * may reallocate record.buf. On success, pstore_mkfile() will keep
745 * the record.buf, so free it only on failure.
746 */
747 for (; stop_loop; stop_loop--) {
748 struct pstore_record *record;
749 int rc;
750
751 record = kzalloc(sizeof(*record), GFP_KERNEL);
752 if (!record) {
753 pr_err("out of memory creating record\n");
754 break;
755 }
756 pstore_record_init(record, psi);
757
758 record->size = psi->read(record);
759
760 /* No more records left in backend? */
761 if (record->size <= 0) {
762 kfree(record);
763 break;
764 }
765
766 decompress_record(record);
767 rc = pstore_mkfile(root, record);
768 if (rc) {
769 /* pstore_mkfile() did not take record, so free it. */
770 kfree(record->buf);
771 kfree(record);
772 if (rc != -EEXIST || !quiet)
773 failed++;
774 }
775 }
776 if (psi->close)
777 psi->close(psi);
778out:
779 mutex_unlock(&psi->read_mutex);
780
781 if (failed)
782 pr_warn("failed to create %d record(s) from '%s'\n",
783 failed, psi->name);
784 if (!stop_loop)
785 pr_err("looping? Too many records seen from '%s'\n",
786 psi->name);
787}
788
789static void pstore_dowork(struct work_struct *work)
790{
791 pstore_get_records(1);
792}
793
794static void pstore_timefunc(struct timer_list *unused)
795{
796 if (pstore_new_entry) {
797 pstore_new_entry = 0;
798 schedule_work(&pstore_work);
799 }
800
801 pstore_timer_kick();
802}
803
804static void __init pstore_choose_compression(void)
805{
806 const struct pstore_zbackend *step;
807
808 if (!compress)
809 return;
810
811 for (step = zbackends; step->name; step++) {
812 if (!strcmp(compress, step->name)) {
813 zbackend = step;
814 return;
815 }
816 }
817}
818
819static int __init pstore_init(void)
820{
821 int ret;
822
823 pstore_choose_compression();
824
825 /*
826 * Check if any pstore backends registered earlier but did not
827 * initialize compression because crypto was not ready. If so,
828 * initialize compression now.
829 */
830 allocate_buf_for_compression();
831
832 ret = pstore_init_fs();
833 if (ret)
834 free_buf_for_compression();
835
836 return ret;
837}
838late_initcall(pstore_init);
839
840static void __exit pstore_exit(void)
841{
842 pstore_exit_fs();
843}
844module_exit(pstore_exit)
845
846MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
847MODULE_LICENSE("GPL");