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
240/*
241 * Called when compression fails, since the printk buffer
242 * would be fetched for compression calling it again when
243 * compression fails would have moved the iterator of
244 * printk buffer which results in fetching old contents.
245 * Copy the recent messages from big_oops_buf to psinfo->buf
246 */
247static size_t copy_kmsg_to_buffer(int hsize, size_t len)
248{
249	size_t total_len;
250	size_t diff;
251
252	total_len = hsize + len;
253
254	if (total_len > psinfo->bufsize) {
255		diff = total_len - psinfo->bufsize + hsize;
256		memcpy(psinfo->buf, big_oops_buf, hsize);
257		memcpy(psinfo->buf + hsize, big_oops_buf + diff,
258					psinfo->bufsize - hsize);
259		total_len = psinfo->bufsize;
260	} else
261		memcpy(psinfo->buf, big_oops_buf, total_len);
262
263	return total_len;
264}
265
266/*
267 * callback from kmsg_dump. (s2,l2) has the most recently
268 * written bytes, older bytes are in (s1,l1). Save as much
269 * as we can from the end of the buffer.
270 */
271static void pstore_dump(struct kmsg_dumper *dumper,
272			enum kmsg_dump_reason reason)
273{
274	unsigned long	total = 0;
275	const char	*why;
276	u64		id;
277	unsigned int	part = 1;
278	unsigned long	flags = 0;
279	int		is_locked = 0;
280	int		ret;
281
282	why = get_reason_str(reason);
283
284	if (pstore_cannot_block_path(reason)) {
285		is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
286		if (!is_locked) {
287			pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
288				       , in_nmi() ? "NMI" : why);
289		}
290	} else
291		spin_lock_irqsave(&psinfo->buf_lock, flags);
292	oopscount++;
293	while (total < kmsg_bytes) {
294		char *dst;
295		unsigned long size;
296		int hsize;
297		int zipped_len = -1;
298		size_t len;
299		bool compressed;
300		size_t total_len;
301
302		if (big_oops_buf) {
303			dst = big_oops_buf;
304			hsize = sprintf(dst, "%s#%d Part%u\n", why,
305							oopscount, part);
306			size = big_oops_buf_sz - hsize;
307
308			if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
309								size, &len))
310				break;
311
312			zipped_len = pstore_compress(dst, psinfo->buf,
313						hsize + len, psinfo->bufsize);
314
315			if (zipped_len > 0) {
316				compressed = true;
317				total_len = zipped_len;
318			} else {
319				compressed = false;
320				total_len = copy_kmsg_to_buffer(hsize, len);
321			}
322		} else {
323			dst = psinfo->buf;
324			hsize = sprintf(dst, "%s#%d Part%u\n", why, oopscount,
325									part);
326			size = psinfo->bufsize - hsize;
327			dst += hsize;
328
329			if (!kmsg_dump_get_buffer(dumper, true, dst,
330								size, &len))
331				break;
332
333			compressed = false;
334			total_len = hsize + len;
335		}
336
337		ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
338				    oopscount, compressed, total_len, psinfo);
339		if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
340			pstore_new_entry = 1;
341
342		total += total_len;
343		part++;
344	}
345	if (pstore_cannot_block_path(reason)) {
346		if (is_locked)
347			spin_unlock_irqrestore(&psinfo->buf_lock, flags);
348	} else
349		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
350}
351
352static struct kmsg_dumper pstore_dumper = {
353	.dump = pstore_dump,
354};
355
356#ifdef CONFIG_PSTORE_CONSOLE
357static void pstore_console_write(struct console *con, const char *s, unsigned c)
358{
359	const char *e = s + c;
360
361	while (s < e) {
362		unsigned long flags;
363		u64 id;
364
365		if (c > psinfo->bufsize)
366			c = psinfo->bufsize;
367
368		if (oops_in_progress) {
369			if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
370				break;
371		} else {
372			spin_lock_irqsave(&psinfo->buf_lock, flags);
373		}
374		memcpy(psinfo->buf, s, c);
375		psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
376		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
377		s += c;
378		c = e - s;
379	}
380}
381
382static struct console pstore_console = {
383	.name	= "pstore",
384	.write	= pstore_console_write,
385	.flags	= CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
386	.index	= -1,
387};
388
389static void pstore_register_console(void)
390{
391	register_console(&pstore_console);
392}
393#else
394static void pstore_register_console(void) {}
395#endif
396
397static int pstore_write_compat(enum pstore_type_id type,
398			       enum kmsg_dump_reason reason,
399			       u64 *id, unsigned int part, int count,
400			       bool compressed, size_t size,
401			       struct pstore_info *psi)
402{
403	return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
404			     size, psi);
405}
406
407/*
408 * platform specific persistent storage driver registers with
409 * us here. If pstore is already mounted, call the platform
410 * read function right away to populate the file system. If not
411 * then the pstore mount code will call us later to fill out
412 * the file system.
413 *
414 * Register with kmsg_dump to save last part of console log on panic.
415 */
416int pstore_register(struct pstore_info *psi)
417{
418	struct module *owner = psi->owner;
419
420	if (backend && strcmp(backend, psi->name))
421		return -EPERM;
422
423	spin_lock(&pstore_lock);
424	if (psinfo) {
425		spin_unlock(&pstore_lock);
426		return -EBUSY;
427	}
428
429	if (!psi->write)
430		psi->write = pstore_write_compat;
431	psinfo = psi;
432	mutex_init(&psinfo->read_mutex);
433	spin_unlock(&pstore_lock);
434
435	if (owner && !try_module_get(owner)) {
436		psinfo = NULL;
437		return -EINVAL;
438	}
439
440	allocate_buf_for_compression();
441
442	if (pstore_is_mounted())
443		pstore_get_records(0);
444
445	kmsg_dump_register(&pstore_dumper);
446
447	if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
448		pstore_register_console();
449		pstore_register_ftrace();
450		pstore_register_pmsg();
451	}
452
453	if (pstore_update_ms >= 0) {
454		pstore_timer.expires = jiffies +
455			msecs_to_jiffies(pstore_update_ms);
456		add_timer(&pstore_timer);
457	}
458
459	pr_info("Registered %s as persistent store backend\n", psi->name);
460
461	return 0;
462}
463EXPORT_SYMBOL_GPL(pstore_register);
464
465/*
466 * Read all the records from the persistent store. Create
467 * files in our filesystem.  Don't warn about -EEXIST errors
468 * when we are re-scanning the backing store looking to add new
469 * error records.
470 */
471void pstore_get_records(int quiet)
472{
473	struct pstore_info *psi = psinfo;
474	char			*buf = NULL;
475	ssize_t			size;
476	u64			id;
477	int			count;
478	enum pstore_type_id	type;
479	struct timespec		time;
480	int			failed = 0, rc;
481	bool			compressed;
482	int			unzipped_len = -1;
483
484	if (!psi)
485		return;
486
487	mutex_lock(&psi->read_mutex);
488	if (psi->open && psi->open(psi))
489		goto out;
490
491	while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
492				psi)) > 0) {
493		if (compressed && (type == PSTORE_TYPE_DMESG)) {
494			if (big_oops_buf)
495				unzipped_len = pstore_decompress(buf,
496							big_oops_buf, size,
497							big_oops_buf_sz);
498
499			if (unzipped_len > 0) {
500				kfree(buf);
501				buf = big_oops_buf;
502				size = unzipped_len;
503				compressed = false;
504			} else {
505				pr_err("decompression failed;returned %d\n",
506				       unzipped_len);
507				compressed = true;
508			}
509		}
510		rc = pstore_mkfile(type, psi->name, id, count, buf,
511				  compressed, (size_t)size, time, psi);
512		if (unzipped_len < 0) {
513			/* Free buffer other than big oops */
514			kfree(buf);
515			buf = NULL;
516		} else
517			unzipped_len = -1;
518		if (rc && (rc != -EEXIST || !quiet))
519			failed++;
520	}
521	if (psi->close)
522		psi->close(psi);
523out:
524	mutex_unlock(&psi->read_mutex);
525
526	if (failed)
527		pr_warn("failed to load %d record(s) from '%s'\n",
528			failed, psi->name);
529}
530
531static void pstore_dowork(struct work_struct *work)
532{
533	pstore_get_records(1);
534}
535
536static void pstore_timefunc(unsigned long dummy)
537{
538	if (pstore_new_entry) {
539		pstore_new_entry = 0;
540		schedule_work(&pstore_work);
541	}
542
543	mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
544}
545
546module_param(backend, charp, 0444);
547MODULE_PARM_DESC(backend, "Pstore backend to use");
548