1/*
2 * Persistent Storage - platform driver interface parts.
3 *
4 * Copyright (C) 2007-2008 Google, Inc.
5 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
6 *
7 *  This program is free software; you can redistribute it and/or modify
8 *  it under the terms of the GNU General Public License version 2 as
9 *  published by the Free Software Foundation.
10 *
11 *  This program is distributed in the hope that it will be useful,
12 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 *  GNU General Public License for more details.
15 *
16 *  You should have received a copy of the GNU General Public License
17 *  along with this program; if not, write to the Free Software
18 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
19 */
20
21#define pr_fmt(fmt) "pstore: " fmt
22
23#include <linux/atomic.h>
24#include <linux/types.h>
25#include <linux/errno.h>
26#include <linux/init.h>
27#include <linux/kmsg_dump.h>
28#include <linux/console.h>
29#include <linux/module.h>
30#include <linux/pstore.h>
31#include <linux/zlib.h>
32#include <linux/string.h>
33#include <linux/timer.h>
34#include <linux/slab.h>
35#include <linux/uaccess.h>
36#include <linux/hardirq.h>
37#include <linux/jiffies.h>
38#include <linux/workqueue.h>
39
40#include "internal.h"
41
42/*
43 * We defer making "oops" entries appear in pstore - see
44 * whether the system is actually still running well enough
45 * to let someone see the entry
46 */
47static int pstore_update_ms = -1;
48module_param_named(update_ms, pstore_update_ms, int, 0600);
49MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
50		 "(default is -1, which means runtime updates are disabled; "
51		 "enabling this option is not safe, it may lead to further "
52		 "corruption on Oopses)");
53
54static int pstore_new_entry;
55
56static void pstore_timefunc(unsigned long);
57static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
58
59static void pstore_dowork(struct work_struct *);
60static DECLARE_WORK(pstore_work, pstore_dowork);
61
62/*
63 * pstore_lock just protects "psinfo" during
64 * calls to pstore_register()
65 */
66static DEFINE_SPINLOCK(pstore_lock);
67struct pstore_info *psinfo;
68
69static char *backend;
70
71/* Compression parameters */
72#define COMPR_LEVEL 6
73#define WINDOW_BITS 12
74#define MEM_LEVEL 4
75static struct z_stream_s stream;
76
77static char *big_oops_buf;
78static size_t big_oops_buf_sz;
79
80/* How much of the console log to snapshot */
81static unsigned long kmsg_bytes = 10240;
82
83void pstore_set_kmsg_bytes(int bytes)
84{
85	kmsg_bytes = bytes;
86}
87
88/* Tag each group of saved records with a sequence number */
89static int	oopscount;
90
91static const char *get_reason_str(enum kmsg_dump_reason reason)
92{
93	switch (reason) {
94	case KMSG_DUMP_PANIC:
95		return "Panic";
96	case KMSG_DUMP_OOPS:
97		return "Oops";
98	case KMSG_DUMP_EMERG:
99		return "Emergency";
100	case KMSG_DUMP_RESTART:
101		return "Restart";
102	case KMSG_DUMP_HALT:
103		return "Halt";
104	case KMSG_DUMP_POWEROFF:
105		return "Poweroff";
106	default:
107		return "Unknown";
108	}
109}
110
111bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
112{
113	/*
114	 * In case of NMI path, pstore shouldn't be blocked
115	 * regardless of reason.
116	 */
117	if (in_nmi())
118		return true;
119
120	switch (reason) {
121	/* In panic case, other cpus are stopped by smp_send_stop(). */
122	case KMSG_DUMP_PANIC:
123	/* Emergency restart shouldn't be blocked by spin lock. */
124	case KMSG_DUMP_EMERG:
125		return true;
126	default:
127		return false;
128	}
129}
130EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
131
132/* Derived from logfs_compress() */
133static int pstore_compress(const void *in, void *out, size_t inlen,
134							size_t outlen)
135{
136	int err, ret;
137
138	ret = -EIO;
139	err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
140						MEM_LEVEL, Z_DEFAULT_STRATEGY);
141	if (err != Z_OK)
142		goto error;
143
144	stream.next_in = in;
145	stream.avail_in = inlen;
146	stream.total_in = 0;
147	stream.next_out = out;
148	stream.avail_out = outlen;
149	stream.total_out = 0;
150
151	err = zlib_deflate(&stream, Z_FINISH);
152	if (err != Z_STREAM_END)
153		goto error;
154
155	err = zlib_deflateEnd(&stream);
156	if (err != Z_OK)
157		goto error;
158
159	if (stream.total_out >= stream.total_in)
160		goto error;
161
162	ret = stream.total_out;
163error:
164	return ret;
165}
166
167/* Derived from logfs_uncompress */
168static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
169{
170	int err, ret;
171
172	ret = -EIO;
173	err = zlib_inflateInit2(&stream, WINDOW_BITS);
174	if (err != Z_OK)
175		goto error;
176
177	stream.next_in = in;
178	stream.avail_in = inlen;
179	stream.total_in = 0;
180	stream.next_out = out;
181	stream.avail_out = outlen;
182	stream.total_out = 0;
183
184	err = zlib_inflate(&stream, Z_FINISH);
185	if (err != Z_STREAM_END)
186		goto error;
187
188	err = zlib_inflateEnd(&stream);
189	if (err != Z_OK)
190		goto error;
191
192	ret = stream.total_out;
193error:
194	return ret;
195}
196
197static void allocate_buf_for_compression(void)
198{
199	size_t size;
200	size_t cmpr;
201
202	switch (psinfo->bufsize) {
203	/* buffer range for efivars */
204	case 1000 ... 2000:
205		cmpr = 56;
206		break;
207	case 2001 ... 3000:
208		cmpr = 54;
209		break;
210	case 3001 ... 3999:
211		cmpr = 52;
212		break;
213	/* buffer range for nvram, erst */
214	case 4000 ... 10000:
215		cmpr = 45;
216		break;
217	default:
218		cmpr = 60;
219		break;
220	}
221
222	big_oops_buf_sz = (psinfo->bufsize * 100) / cmpr;
223	big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
224	if (big_oops_buf) {
225		size = max(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
226			zlib_inflate_workspacesize());
227		stream.workspace = kmalloc(size, GFP_KERNEL);
228		if (!stream.workspace) {
229			pr_err("No memory for compression workspace; skipping compression\n");
230			kfree(big_oops_buf);
231			big_oops_buf = NULL;
232		}
233	} else {
234		pr_err("No memory for uncompressed data; skipping compression\n");
235		stream.workspace = NULL;
236	}
237
238}
239
240static void free_buf_for_compression(void)
241{
242	kfree(stream.workspace);
243	stream.workspace = NULL;
244	kfree(big_oops_buf);
245	big_oops_buf = NULL;
246}
247
248/*
249 * Called when compression fails, since the printk buffer
250 * would be fetched for compression calling it again when
251 * compression fails would have moved the iterator of
252 * printk buffer which results in fetching old contents.
253 * Copy the recent messages from big_oops_buf to psinfo->buf
254 */
255static size_t copy_kmsg_to_buffer(int hsize, size_t len)
256{
257	size_t total_len;
258	size_t diff;
259
260	total_len = hsize + len;
261
262	if (total_len > psinfo->bufsize) {
263		diff = total_len - psinfo->bufsize + hsize;
264		memcpy(psinfo->buf, big_oops_buf, hsize);
265		memcpy(psinfo->buf + hsize, big_oops_buf + diff,
266					psinfo->bufsize - hsize);
267		total_len = psinfo->bufsize;
268	} else
269		memcpy(psinfo->buf, big_oops_buf, total_len);
270
271	return total_len;
272}
273
274/*
275 * callback from kmsg_dump. (s2,l2) has the most recently
276 * written bytes, older bytes are in (s1,l1). Save as much
277 * as we can from the end of the buffer.
278 */
279static void pstore_dump(struct kmsg_dumper *dumper,
280			enum kmsg_dump_reason reason)
281{
282	unsigned long	total = 0;
283	const char	*why;
284	u64		id;
285	unsigned int	part = 1;
286	unsigned long	flags = 0;
287	int		is_locked = 0;
288	int		ret;
289
290	why = get_reason_str(reason);
291
292	if (pstore_cannot_block_path(reason)) {
293		is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
294		if (!is_locked) {
295			pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
296				       , in_nmi() ? "NMI" : why);
297		}
298	} else
299		spin_lock_irqsave(&psinfo->buf_lock, flags);
300	oopscount++;
301	while (total < kmsg_bytes) {
302		char *dst;
303		unsigned long size;
304		int hsize;
305		int zipped_len = -1;
306		size_t len;
307		bool compressed;
308		size_t total_len;
309
310		if (big_oops_buf && is_locked) {
311			dst = big_oops_buf;
312			hsize = sprintf(dst, "%s#%d Part%u\n", why,
313							oopscount, part);
314			size = big_oops_buf_sz - hsize;
315
316			if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
317								size, &len))
318				break;
319
320			zipped_len = pstore_compress(dst, psinfo->buf,
321						hsize + len, psinfo->bufsize);
322
323			if (zipped_len > 0) {
324				compressed = true;
325				total_len = zipped_len;
326			} else {
327				compressed = false;
328				total_len = copy_kmsg_to_buffer(hsize, len);
329			}
330		} else {
331			dst = psinfo->buf;
332			hsize = sprintf(dst, "%s#%d Part%u\n", why, oopscount,
333									part);
334			size = psinfo->bufsize - hsize;
335			dst += hsize;
336
337			if (!kmsg_dump_get_buffer(dumper, true, dst,
338								size, &len))
339				break;
340
341			compressed = false;
342			total_len = hsize + len;
343		}
344
345		ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
346				    oopscount, compressed, total_len, psinfo);
347		if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
348			pstore_new_entry = 1;
349
350		total += total_len;
351		part++;
352	}
353	if (pstore_cannot_block_path(reason)) {
354		if (is_locked)
355			spin_unlock_irqrestore(&psinfo->buf_lock, flags);
356	} else
357		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
358}
359
360static struct kmsg_dumper pstore_dumper = {
361	.dump = pstore_dump,
362};
363
364/*
365 * Register with kmsg_dump to save last part of console log on panic.
366 */
367static void pstore_register_kmsg(void)
368{
369	kmsg_dump_register(&pstore_dumper);
370}
371
372static void pstore_unregister_kmsg(void)
373{
374	kmsg_dump_unregister(&pstore_dumper);
375}
376
377#ifdef CONFIG_PSTORE_CONSOLE
378static void pstore_console_write(struct console *con, const char *s, unsigned c)
379{
380	const char *e = s + c;
381
382	while (s < e) {
383		unsigned long flags;
384		u64 id;
385
386		if (c > psinfo->bufsize)
387			c = psinfo->bufsize;
388
389		if (oops_in_progress) {
390			if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
391				break;
392		} else {
393			spin_lock_irqsave(&psinfo->buf_lock, flags);
394		}
395		memcpy(psinfo->buf, s, c);
396		psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
397		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
398		s += c;
399		c = e - s;
400	}
401}
402
403static struct console pstore_console = {
404	.name	= "pstore",
405	.write	= pstore_console_write,
406	.flags	= CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
407	.index	= -1,
408};
409
410static void pstore_register_console(void)
411{
412	register_console(&pstore_console);
413}
414
415static void pstore_unregister_console(void)
416{
417	unregister_console(&pstore_console);
418}
419#else
420static void pstore_register_console(void) {}
421static void pstore_unregister_console(void) {}
422#endif
423
424static int pstore_write_compat(enum pstore_type_id type,
425			       enum kmsg_dump_reason reason,
426			       u64 *id, unsigned int part, int count,
427			       bool compressed, size_t size,
428			       struct pstore_info *psi)
429{
430	return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
431			     size, psi);
432}
433
434/*
435 * platform specific persistent storage driver registers with
436 * us here. If pstore is already mounted, call the platform
437 * read function right away to populate the file system. If not
438 * then the pstore mount code will call us later to fill out
439 * the file system.
440 */
441int pstore_register(struct pstore_info *psi)
442{
443	struct module *owner = psi->owner;
444
445	if (backend && strcmp(backend, psi->name))
446		return -EPERM;
447
448	spin_lock(&pstore_lock);
449	if (psinfo) {
450		spin_unlock(&pstore_lock);
451		return -EBUSY;
452	}
453
454	if (!psi->write)
455		psi->write = pstore_write_compat;
456	psinfo = psi;
457	mutex_init(&psinfo->read_mutex);
458	spin_unlock(&pstore_lock);
459
460	if (owner && !try_module_get(owner)) {
461		psinfo = NULL;
462		return -EINVAL;
463	}
464
465	allocate_buf_for_compression();
466
467	if (pstore_is_mounted())
468		pstore_get_records(0);
469
470	pstore_register_kmsg();
471
472	if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
473		pstore_register_console();
474		pstore_register_ftrace();
475		pstore_register_pmsg();
476	}
477
478	if (pstore_update_ms >= 0) {
479		pstore_timer.expires = jiffies +
480			msecs_to_jiffies(pstore_update_ms);
481		add_timer(&pstore_timer);
482	}
483
484	/*
485	 * Update the module parameter backend, so it is visible
486	 * through /sys/module/pstore/parameters/backend
487	 */
488	backend = psi->name;
489
490	module_put(owner);
491
492	pr_info("Registered %s as persistent store backend\n", psi->name);
493
494	return 0;
495}
496EXPORT_SYMBOL_GPL(pstore_register);
497
498void pstore_unregister(struct pstore_info *psi)
499{
500	pstore_unregister_pmsg();
501	pstore_unregister_ftrace();
502	pstore_unregister_console();
503	pstore_unregister_kmsg();
504
505	free_buf_for_compression();
506
507	psinfo = NULL;
508	backend = NULL;
509}
510EXPORT_SYMBOL_GPL(pstore_unregister);
511
512/*
513 * Read all the records from the persistent store. Create
514 * files in our filesystem.  Don't warn about -EEXIST errors
515 * when we are re-scanning the backing store looking to add new
516 * error records.
517 */
518void pstore_get_records(int quiet)
519{
520	struct pstore_info *psi = psinfo;
521	char			*buf = NULL;
522	ssize_t			size;
523	u64			id;
524	int			count;
525	enum pstore_type_id	type;
526	struct timespec		time;
527	int			failed = 0, rc;
528	bool			compressed;
529	int			unzipped_len = -1;
530
531	if (!psi)
532		return;
533
534	mutex_lock(&psi->read_mutex);
535	if (psi->open && psi->open(psi))
536		goto out;
537
538	while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
539				psi)) > 0) {
540		if (compressed && (type == PSTORE_TYPE_DMESG)) {
541			if (big_oops_buf)
542				unzipped_len = pstore_decompress(buf,
543							big_oops_buf, size,
544							big_oops_buf_sz);
545
546			if (unzipped_len > 0) {
547				kfree(buf);
548				buf = big_oops_buf;
549				size = unzipped_len;
550				compressed = false;
551			} else {
552				pr_err("decompression failed;returned %d\n",
553				       unzipped_len);
554				compressed = true;
555			}
556		}
557		rc = pstore_mkfile(type, psi->name, id, count, buf,
558				  compressed, (size_t)size, time, psi);
559		if (unzipped_len < 0) {
560			/* Free buffer other than big oops */
561			kfree(buf);
562			buf = NULL;
563		} else
564			unzipped_len = -1;
565		if (rc && (rc != -EEXIST || !quiet))
566			failed++;
567	}
568	if (psi->close)
569		psi->close(psi);
570out:
571	mutex_unlock(&psi->read_mutex);
572
573	if (failed)
574		pr_warn("failed to load %d record(s) from '%s'\n",
575			failed, psi->name);
576}
577
578static void pstore_dowork(struct work_struct *work)
579{
580	pstore_get_records(1);
581}
582
583static void pstore_timefunc(unsigned long dummy)
584{
585	if (pstore_new_entry) {
586		pstore_new_entry = 0;
587		schedule_work(&pstore_work);
588	}
589
590	mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
591}
592
593module_param(backend, charp, 0444);
594MODULE_PARM_DESC(backend, "Pstore backend to use");
595