xref: /openbmc/linux/fs/pstore/inode.c (revision e6dec923) 
1 /*
2  * Persistent Storage - ramfs 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/module.h>
21 #include <linux/fs.h>
22 #include <linux/fsnotify.h>
23 #include <linux/pagemap.h>
24 #include <linux/highmem.h>
25 #include <linux/time.h>
26 #include <linux/init.h>
27 #include <linux/list.h>
28 #include <linux/string.h>
29 #include <linux/mount.h>
30 #include <linux/seq_file.h>
31 #include <linux/ramfs.h>
32 #include <linux/parser.h>
33 #include <linux/sched.h>
34 #include <linux/magic.h>
35 #include <linux/pstore.h>
36 #include <linux/slab.h>
37 #include <linux/spinlock.h>
38 #include <linux/uaccess.h>
39 #include <linux/syslog.h>
40 
41 #include "internal.h"
42 
43 #define	PSTORE_NAMELEN	64
44 
45 static DEFINE_SPINLOCK(allpstore_lock);
46 static LIST_HEAD(allpstore);
47 
48 struct pstore_private {
49 	struct list_head list;
50 	struct pstore_record *record;
51 	size_t total_size;
52 };
53 
54 struct pstore_ftrace_seq_data {
55 	const void *ptr;
56 	size_t off;
57 	size_t size;
58 };
59 
60 #define REC_SIZE sizeof(struct pstore_ftrace_record)
61 
62 static void free_pstore_private(struct pstore_private *private)
63 {
64 	if (!private)
65 		return;
66 	if (private->record) {
67 		kfree(private->record->buf);
68 		kfree(private->record);
69 	}
70 	kfree(private);
71 }
72 
73 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
74 {
75 	struct pstore_private *ps = s->private;
76 	struct pstore_ftrace_seq_data *data;
77 
78 	data = kzalloc(sizeof(*data), GFP_KERNEL);
79 	if (!data)
80 		return NULL;
81 
82 	data->off = ps->total_size % REC_SIZE;
83 	data->off += *pos * REC_SIZE;
84 	if (data->off + REC_SIZE > ps->total_size) {
85 		kfree(data);
86 		return NULL;
87 	}
88 
89 	return data;
90 
91 }
92 
93 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
94 {
95 	kfree(v);
96 }
97 
98 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
99 {
100 	struct pstore_private *ps = s->private;
101 	struct pstore_ftrace_seq_data *data = v;
102 
103 	data->off += REC_SIZE;
104 	if (data->off + REC_SIZE > ps->total_size)
105 		return NULL;
106 
107 	(*pos)++;
108 	return data;
109 }
110 
111 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
112 {
113 	struct pstore_private *ps = s->private;
114 	struct pstore_ftrace_seq_data *data = v;
115 	struct pstore_ftrace_record *rec;
116 
117 	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
118 
119 	seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %pf <- %pF\n",
120 		   pstore_ftrace_decode_cpu(rec),
121 		   pstore_ftrace_read_timestamp(rec),
122 		   rec->ip, rec->parent_ip, (void *)rec->ip,
123 		   (void *)rec->parent_ip);
124 
125 	return 0;
126 }
127 
128 static const struct seq_operations pstore_ftrace_seq_ops = {
129 	.start	= pstore_ftrace_seq_start,
130 	.next	= pstore_ftrace_seq_next,
131 	.stop	= pstore_ftrace_seq_stop,
132 	.show	= pstore_ftrace_seq_show,
133 };
134 
135 static int pstore_check_syslog_permissions(struct pstore_private *ps)
136 {
137 	switch (ps->record->type) {
138 	case PSTORE_TYPE_DMESG:
139 	case PSTORE_TYPE_CONSOLE:
140 		return check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
141 			SYSLOG_FROM_READER);
142 	default:
143 		return 0;
144 	}
145 }
146 
147 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
148 						size_t count, loff_t *ppos)
149 {
150 	struct seq_file *sf = file->private_data;
151 	struct pstore_private *ps = sf->private;
152 
153 	if (ps->record->type == PSTORE_TYPE_FTRACE)
154 		return seq_read(file, userbuf, count, ppos);
155 	return simple_read_from_buffer(userbuf, count, ppos,
156 				       ps->record->buf, ps->total_size);
157 }
158 
159 static int pstore_file_open(struct inode *inode, struct file *file)
160 {
161 	struct pstore_private *ps = inode->i_private;
162 	struct seq_file *sf;
163 	int err;
164 	const struct seq_operations *sops = NULL;
165 
166 	err = pstore_check_syslog_permissions(ps);
167 	if (err)
168 		return err;
169 
170 	if (ps->record->type == PSTORE_TYPE_FTRACE)
171 		sops = &pstore_ftrace_seq_ops;
172 
173 	err = seq_open(file, sops);
174 	if (err < 0)
175 		return err;
176 
177 	sf = file->private_data;
178 	sf->private = ps;
179 
180 	return 0;
181 }
182 
183 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
184 {
185 	struct seq_file *sf = file->private_data;
186 
187 	if (sf->op)
188 		return seq_lseek(file, off, whence);
189 	return default_llseek(file, off, whence);
190 }
191 
192 static const struct file_operations pstore_file_operations = {
193 	.open		= pstore_file_open,
194 	.read		= pstore_file_read,
195 	.llseek		= pstore_file_llseek,
196 	.release	= seq_release,
197 };
198 
199 /*
200  * When a file is unlinked from our file system we call the
201  * platform driver to erase the record from persistent store.
202  */
203 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
204 {
205 	struct pstore_private *p = d_inode(dentry)->i_private;
206 	struct pstore_record *record = p->record;
207 	int err;
208 
209 	err = pstore_check_syslog_permissions(p);
210 	if (err)
211 		return err;
212 
213 	if (!record->psi->erase)
214 		return -EPERM;
215 
216 	mutex_lock(&record->psi->read_mutex);
217 	record->psi->erase(record);
218 	mutex_unlock(&record->psi->read_mutex);
219 
220 	return simple_unlink(dir, dentry);
221 }
222 
223 static void pstore_evict_inode(struct inode *inode)
224 {
225 	struct pstore_private	*p = inode->i_private;
226 	unsigned long		flags;
227 
228 	clear_inode(inode);
229 	if (p) {
230 		spin_lock_irqsave(&allpstore_lock, flags);
231 		list_del(&p->list);
232 		spin_unlock_irqrestore(&allpstore_lock, flags);
233 		free_pstore_private(p);
234 	}
235 }
236 
237 static const struct inode_operations pstore_dir_inode_operations = {
238 	.lookup		= simple_lookup,
239 	.unlink		= pstore_unlink,
240 };
241 
242 static struct inode *pstore_get_inode(struct super_block *sb)
243 {
244 	struct inode *inode = new_inode(sb);
245 	if (inode) {
246 		inode->i_ino = get_next_ino();
247 		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
248 	}
249 	return inode;
250 }
251 
252 enum {
253 	Opt_kmsg_bytes, Opt_err
254 };
255 
256 static const match_table_t tokens = {
257 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
258 	{Opt_err, NULL}
259 };
260 
261 static void parse_options(char *options)
262 {
263 	char		*p;
264 	substring_t	args[MAX_OPT_ARGS];
265 	int		option;
266 
267 	if (!options)
268 		return;
269 
270 	while ((p = strsep(&options, ",")) != NULL) {
271 		int token;
272 
273 		if (!*p)
274 			continue;
275 
276 		token = match_token(p, tokens, args);
277 		switch (token) {
278 		case Opt_kmsg_bytes:
279 			if (!match_int(&args[0], &option))
280 				pstore_set_kmsg_bytes(option);
281 			break;
282 		}
283 	}
284 }
285 
286 /*
287  * Display the mount options in /proc/mounts.
288  */
289 static int pstore_show_options(struct seq_file *m, struct dentry *root)
290 {
291 	if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
292 		seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
293 	return 0;
294 }
295 
296 static int pstore_remount(struct super_block *sb, int *flags, char *data)
297 {
298 	sync_filesystem(sb);
299 	parse_options(data);
300 
301 	return 0;
302 }
303 
304 static const struct super_operations pstore_ops = {
305 	.statfs		= simple_statfs,
306 	.drop_inode	= generic_delete_inode,
307 	.evict_inode	= pstore_evict_inode,
308 	.remount_fs	= pstore_remount,
309 	.show_options	= pstore_show_options,
310 };
311 
312 static struct super_block *pstore_sb;
313 
314 bool pstore_is_mounted(void)
315 {
316 	return pstore_sb != NULL;
317 }
318 
319 /*
320  * Make a regular file in the root directory of our file system.
321  * Load it up with "size" bytes of data from "buf".
322  * Set the mtime & ctime to the date that this record was originally stored.
323  */
324 int pstore_mkfile(struct dentry *root, struct pstore_record *record)
325 {
326 	struct dentry		*dentry;
327 	struct inode		*inode;
328 	int			rc = 0;
329 	char			name[PSTORE_NAMELEN];
330 	struct pstore_private	*private, *pos;
331 	unsigned long		flags;
332 	size_t			size = record->size + record->ecc_notice_size;
333 
334 	WARN_ON(!inode_is_locked(d_inode(root)));
335 
336 	spin_lock_irqsave(&allpstore_lock, flags);
337 	list_for_each_entry(pos, &allpstore, list) {
338 		if (pos->record->type == record->type &&
339 		    pos->record->id == record->id &&
340 		    pos->record->psi == record->psi) {
341 			rc = -EEXIST;
342 			break;
343 		}
344 	}
345 	spin_unlock_irqrestore(&allpstore_lock, flags);
346 	if (rc)
347 		return rc;
348 
349 	rc = -ENOMEM;
350 	inode = pstore_get_inode(root->d_sb);
351 	if (!inode)
352 		goto fail;
353 	inode->i_mode = S_IFREG | 0444;
354 	inode->i_fop = &pstore_file_operations;
355 	private = kzalloc(sizeof(*private), GFP_KERNEL);
356 	if (!private)
357 		goto fail_alloc;
358 	private->record = record;
359 
360 	switch (record->type) {
361 	case PSTORE_TYPE_DMESG:
362 		scnprintf(name, sizeof(name), "dmesg-%s-%llu%s",
363 			  record->psi->name, record->id,
364 			  record->compressed ? ".enc.z" : "");
365 		break;
366 	case PSTORE_TYPE_CONSOLE:
367 		scnprintf(name, sizeof(name), "console-%s-%llu",
368 			  record->psi->name, record->id);
369 		break;
370 	case PSTORE_TYPE_FTRACE:
371 		scnprintf(name, sizeof(name), "ftrace-%s-%llu",
372 			  record->psi->name, record->id);
373 		break;
374 	case PSTORE_TYPE_MCE:
375 		scnprintf(name, sizeof(name), "mce-%s-%llu",
376 			  record->psi->name, record->id);
377 		break;
378 	case PSTORE_TYPE_PPC_RTAS:
379 		scnprintf(name, sizeof(name), "rtas-%s-%llu",
380 			  record->psi->name, record->id);
381 		break;
382 	case PSTORE_TYPE_PPC_OF:
383 		scnprintf(name, sizeof(name), "powerpc-ofw-%s-%llu",
384 			  record->psi->name, record->id);
385 		break;
386 	case PSTORE_TYPE_PPC_COMMON:
387 		scnprintf(name, sizeof(name), "powerpc-common-%s-%llu",
388 			  record->psi->name, record->id);
389 		break;
390 	case PSTORE_TYPE_PMSG:
391 		scnprintf(name, sizeof(name), "pmsg-%s-%llu",
392 			  record->psi->name, record->id);
393 		break;
394 	case PSTORE_TYPE_PPC_OPAL:
395 		scnprintf(name, sizeof(name), "powerpc-opal-%s-%llu",
396 			  record->psi->name, record->id);
397 		break;
398 	case PSTORE_TYPE_UNKNOWN:
399 		scnprintf(name, sizeof(name), "unknown-%s-%llu",
400 			  record->psi->name, record->id);
401 		break;
402 	default:
403 		scnprintf(name, sizeof(name), "type%d-%s-%llu",
404 			  record->type, record->psi->name, record->id);
405 		break;
406 	}
407 
408 	dentry = d_alloc_name(root, name);
409 	if (!dentry)
410 		goto fail_private;
411 
412 	inode->i_size = private->total_size = size;
413 
414 	inode->i_private = private;
415 
416 	if (record->time.tv_sec)
417 		inode->i_mtime = inode->i_ctime = record->time;
418 
419 	d_add(dentry, inode);
420 
421 	spin_lock_irqsave(&allpstore_lock, flags);
422 	list_add(&private->list, &allpstore);
423 	spin_unlock_irqrestore(&allpstore_lock, flags);
424 
425 	return 0;
426 
427 fail_private:
428 	free_pstore_private(private);
429 fail_alloc:
430 	iput(inode);
431 
432 fail:
433 	return rc;
434 }
435 
436 /*
437  * Read all the records from the persistent store. Create
438  * files in our filesystem.  Don't warn about -EEXIST errors
439  * when we are re-scanning the backing store looking to add new
440  * error records.
441  */
442 void pstore_get_records(int quiet)
443 {
444 	struct pstore_info *psi = psinfo;
445 	struct dentry *root;
446 
447 	if (!psi || !pstore_sb)
448 		return;
449 
450 	root = pstore_sb->s_root;
451 
452 	inode_lock(d_inode(root));
453 	pstore_get_backend_records(psi, root, quiet);
454 	inode_unlock(d_inode(root));
455 }
456 
457 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
458 {
459 	struct inode *inode;
460 
461 	pstore_sb = sb;
462 
463 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
464 	sb->s_blocksize		= PAGE_SIZE;
465 	sb->s_blocksize_bits	= PAGE_SHIFT;
466 	sb->s_magic		= PSTOREFS_MAGIC;
467 	sb->s_op		= &pstore_ops;
468 	sb->s_time_gran		= 1;
469 
470 	parse_options(data);
471 
472 	inode = pstore_get_inode(sb);
473 	if (inode) {
474 		inode->i_mode = S_IFDIR | 0755;
475 		inode->i_op = &pstore_dir_inode_operations;
476 		inode->i_fop = &simple_dir_operations;
477 		inc_nlink(inode);
478 	}
479 	sb->s_root = d_make_root(inode);
480 	if (!sb->s_root)
481 		return -ENOMEM;
482 
483 	pstore_get_records(0);
484 
485 	return 0;
486 }
487 
488 static struct dentry *pstore_mount(struct file_system_type *fs_type,
489 	int flags, const char *dev_name, void *data)
490 {
491 	return mount_single(fs_type, flags, data, pstore_fill_super);
492 }
493 
494 static void pstore_kill_sb(struct super_block *sb)
495 {
496 	kill_litter_super(sb);
497 	pstore_sb = NULL;
498 }
499 
500 static struct file_system_type pstore_fs_type = {
501 	.owner          = THIS_MODULE,
502 	.name		= "pstore",
503 	.mount		= pstore_mount,
504 	.kill_sb	= pstore_kill_sb,
505 };
506 
507 static int __init init_pstore_fs(void)
508 {
509 	int err;
510 
511 	/* Create a convenient mount point for people to access pstore */
512 	err = sysfs_create_mount_point(fs_kobj, "pstore");
513 	if (err)
514 		goto out;
515 
516 	err = register_filesystem(&pstore_fs_type);
517 	if (err < 0)
518 		sysfs_remove_mount_point(fs_kobj, "pstore");
519 
520 out:
521 	return err;
522 }
523 module_init(init_pstore_fs)
524 
525 static void __exit exit_pstore_fs(void)
526 {
527 	unregister_filesystem(&pstore_fs_type);
528 	sysfs_remove_mount_point(fs_kobj, "pstore");
529 }
530 module_exit(exit_pstore_fs)
531 
532 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
533 MODULE_LICENSE("GPL");
534