xref: /openbmc/linux/fs/pstore/platform.c (revision 98e44fda2ea19c0e8b0a2e0e4dcd3461251f09ea) 
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  */
47 static int pstore_update_ms = -1;
48 module_param_named(update_ms, pstore_update_ms, int, 0600);
49 MODULE_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 
54 static int pstore_new_entry;
55 
56 static void pstore_timefunc(unsigned long);
57 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
58 
59 static void pstore_dowork(struct work_struct *);
60 static DECLARE_WORK(pstore_work, pstore_dowork);
61 
62 /*
63  * pstore_lock just protects "psinfo" during
64  * calls to pstore_register()
65  */
66 static DEFINE_SPINLOCK(pstore_lock);
67 struct pstore_info *psinfo;
68 
69 static char *backend;
70 
71 /* Compression parameters */
72 #define COMPR_LEVEL 6
73 #define WINDOW_BITS 12
74 #define MEM_LEVEL 4
75 static struct z_stream_s stream;
76 
77 static char *big_oops_buf;
78 static size_t big_oops_buf_sz;
79 
80 /* How much of the console log to snapshot */
81 static unsigned long kmsg_bytes = 10240;
82 
83 void pstore_set_kmsg_bytes(int bytes)
84 {
85 	kmsg_bytes = bytes;
86 }
87 
88 /* Tag each group of saved records with a sequence number */
89 static int	oopscount;
90 
91 static 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 
111 bool 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 }
130 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
131 
132 /* Derived from logfs_compress() */
133 static 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;
163 error:
164 	return ret;
165 }
166 
167 /* Derived from logfs_uncompress */
168 static 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;
193 error:
194 	return ret;
195 }
196 
197 static 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 static 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  */
255 static 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  */
279 static 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;
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 		is_locked = 1;
301 	}
302 	oopscount++;
303 	while (total < kmsg_bytes) {
304 		char *dst;
305 		unsigned long size;
306 		int hsize;
307 		int zipped_len = -1;
308 		size_t len;
309 		bool compressed;
310 		size_t total_len;
311 
312 		if (big_oops_buf && is_locked) {
313 			dst = big_oops_buf;
314 			hsize = sprintf(dst, "%s#%d Part%u\n", why,
315 							oopscount, part);
316 			size = big_oops_buf_sz - hsize;
317 
318 			if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
319 								size, &len))
320 				break;
321 
322 			zipped_len = pstore_compress(dst, psinfo->buf,
323 						hsize + len, psinfo->bufsize);
324 
325 			if (zipped_len > 0) {
326 				compressed = true;
327 				total_len = zipped_len;
328 			} else {
329 				compressed = false;
330 				total_len = copy_kmsg_to_buffer(hsize, len);
331 			}
332 		} else {
333 			dst = psinfo->buf;
334 			hsize = sprintf(dst, "%s#%d Part%u\n", why, oopscount,
335 									part);
336 			size = psinfo->bufsize - hsize;
337 			dst += hsize;
338 
339 			if (!kmsg_dump_get_buffer(dumper, true, dst,
340 								size, &len))
341 				break;
342 
343 			compressed = false;
344 			total_len = hsize + len;
345 		}
346 
347 		ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
348 				    oopscount, compressed, total_len, psinfo);
349 		if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
350 			pstore_new_entry = 1;
351 
352 		total += total_len;
353 		part++;
354 	}
355 	if (is_locked)
356 		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
357 }
358 
359 static struct kmsg_dumper pstore_dumper = {
360 	.dump = pstore_dump,
361 };
362 
363 /*
364  * Register with kmsg_dump to save last part of console log on panic.
365  */
366 static void pstore_register_kmsg(void)
367 {
368 	kmsg_dump_register(&pstore_dumper);
369 }
370 
371 static void pstore_unregister_kmsg(void)
372 {
373 	kmsg_dump_unregister(&pstore_dumper);
374 }
375 
376 #ifdef CONFIG_PSTORE_CONSOLE
377 static void pstore_console_write(struct console *con, const char *s, unsigned c)
378 {
379 	const char *e = s + c;
380 
381 	while (s < e) {
382 		unsigned long flags;
383 		u64 id;
384 
385 		if (c > psinfo->bufsize)
386 			c = psinfo->bufsize;
387 
388 		if (oops_in_progress) {
389 			if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
390 				break;
391 		} else {
392 			spin_lock_irqsave(&psinfo->buf_lock, flags);
393 		}
394 		memcpy(psinfo->buf, s, c);
395 		psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
396 		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
397 		s += c;
398 		c = e - s;
399 	}
400 }
401 
402 static struct console pstore_console = {
403 	.name	= "pstore",
404 	.write	= pstore_console_write,
405 	.flags	= CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
406 	.index	= -1,
407 };
408 
409 static void pstore_register_console(void)
410 {
411 	register_console(&pstore_console);
412 }
413 
414 static void pstore_unregister_console(void)
415 {
416 	unregister_console(&pstore_console);
417 }
418 #else
419 static void pstore_register_console(void) {}
420 static void pstore_unregister_console(void) {}
421 #endif
422 
423 static int pstore_write_compat(enum pstore_type_id type,
424 			       enum kmsg_dump_reason reason,
425 			       u64 *id, unsigned int part, int count,
426 			       bool compressed, size_t size,
427 			       struct pstore_info *psi)
428 {
429 	return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
430 			     size, psi);
431 }
432 
433 /*
434  * platform specific persistent storage driver registers with
435  * us here. If pstore is already mounted, call the platform
436  * read function right away to populate the file system. If not
437  * then the pstore mount code will call us later to fill out
438  * the file system.
439  */
440 int pstore_register(struct pstore_info *psi)
441 {
442 	struct module *owner = psi->owner;
443 
444 	if (backend && strcmp(backend, psi->name))
445 		return -EPERM;
446 
447 	spin_lock(&pstore_lock);
448 	if (psinfo) {
449 		spin_unlock(&pstore_lock);
450 		return -EBUSY;
451 	}
452 
453 	if (!psi->write)
454 		psi->write = pstore_write_compat;
455 	psinfo = psi;
456 	mutex_init(&psinfo->read_mutex);
457 	spin_unlock(&pstore_lock);
458 
459 	if (owner && !try_module_get(owner)) {
460 		psinfo = NULL;
461 		return -EINVAL;
462 	}
463 
464 	allocate_buf_for_compression();
465 
466 	if (pstore_is_mounted())
467 		pstore_get_records(0);
468 
469 	pstore_register_kmsg();
470 
471 	if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
472 		pstore_register_console();
473 		pstore_register_ftrace();
474 		pstore_register_pmsg();
475 	}
476 
477 	if (pstore_update_ms >= 0) {
478 		pstore_timer.expires = jiffies +
479 			msecs_to_jiffies(pstore_update_ms);
480 		add_timer(&pstore_timer);
481 	}
482 
483 	/*
484 	 * Update the module parameter backend, so it is visible
485 	 * through /sys/module/pstore/parameters/backend
486 	 */
487 	backend = psi->name;
488 
489 	module_put(owner);
490 
491 	pr_info("Registered %s as persistent store backend\n", psi->name);
492 
493 	return 0;
494 }
495 EXPORT_SYMBOL_GPL(pstore_register);
496 
497 void pstore_unregister(struct pstore_info *psi)
498 {
499 	if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
500 		pstore_unregister_pmsg();
501 		pstore_unregister_ftrace();
502 		pstore_unregister_console();
503 	}
504 	pstore_unregister_kmsg();
505 
506 	free_buf_for_compression();
507 
508 	psinfo = NULL;
509 	backend = NULL;
510 }
511 EXPORT_SYMBOL_GPL(pstore_unregister);
512 
513 /*
514  * Read all the records from the persistent store. Create
515  * files in our filesystem.  Don't warn about -EEXIST errors
516  * when we are re-scanning the backing store looking to add new
517  * error records.
518  */
519 void pstore_get_records(int quiet)
520 {
521 	struct pstore_info *psi = psinfo;
522 	char			*buf = NULL;
523 	ssize_t			size;
524 	u64			id;
525 	int			count;
526 	enum pstore_type_id	type;
527 	struct timespec		time;
528 	int			failed = 0, rc;
529 	bool			compressed;
530 	int			unzipped_len = -1;
531 
532 	if (!psi)
533 		return;
534 
535 	mutex_lock(&psi->read_mutex);
536 	if (psi->open && psi->open(psi))
537 		goto out;
538 
539 	while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
540 				psi)) > 0) {
541 		if (compressed && (type == PSTORE_TYPE_DMESG)) {
542 			if (big_oops_buf)
543 				unzipped_len = pstore_decompress(buf,
544 							big_oops_buf, size,
545 							big_oops_buf_sz);
546 
547 			if (unzipped_len > 0) {
548 				kfree(buf);
549 				buf = big_oops_buf;
550 				size = unzipped_len;
551 				compressed = false;
552 			} else {
553 				pr_err("decompression failed;returned %d\n",
554 				       unzipped_len);
555 				compressed = true;
556 			}
557 		}
558 		rc = pstore_mkfile(type, psi->name, id, count, buf,
559 				  compressed, (size_t)size, time, psi);
560 		if (unzipped_len < 0) {
561 			/* Free buffer other than big oops */
562 			kfree(buf);
563 			buf = NULL;
564 		} else
565 			unzipped_len = -1;
566 		if (rc && (rc != -EEXIST || !quiet))
567 			failed++;
568 	}
569 	if (psi->close)
570 		psi->close(psi);
571 out:
572 	mutex_unlock(&psi->read_mutex);
573 
574 	if (failed)
575 		pr_warn("failed to load %d record(s) from '%s'\n",
576 			failed, psi->name);
577 }
578 
579 static void pstore_dowork(struct work_struct *work)
580 {
581 	pstore_get_records(1);
582 }
583 
584 static void pstore_timefunc(unsigned long dummy)
585 {
586 	if (pstore_new_entry) {
587 		pstore_new_entry = 0;
588 		schedule_work(&pstore_work);
589 	}
590 
591 	mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
592 }
593 
594 module_param(backend, charp, 0444);
595 MODULE_PARM_DESC(backend, "Pstore backend to use");
596