xref: /openbmc/linux/fs/pstore/inode.c (revision 9cfc5c90) 
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_info *psi;
51 	enum pstore_type_id type;
52 	u64	id;
53 	int	count;
54 	ssize_t	size;
55 	char	data[];
56 };
57 
58 struct pstore_ftrace_seq_data {
59 	const void *ptr;
60 	size_t off;
61 	size_t size;
62 };
63 
64 #define REC_SIZE sizeof(struct pstore_ftrace_record)
65 
66 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
67 {
68 	struct pstore_private *ps = s->private;
69 	struct pstore_ftrace_seq_data *data;
70 
71 	data = kzalloc(sizeof(*data), GFP_KERNEL);
72 	if (!data)
73 		return NULL;
74 
75 	data->off = ps->size % REC_SIZE;
76 	data->off += *pos * REC_SIZE;
77 	if (data->off + REC_SIZE > ps->size) {
78 		kfree(data);
79 		return NULL;
80 	}
81 
82 	return data;
83 
84 }
85 
86 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
87 {
88 	kfree(v);
89 }
90 
91 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
92 {
93 	struct pstore_private *ps = s->private;
94 	struct pstore_ftrace_seq_data *data = v;
95 
96 	data->off += REC_SIZE;
97 	if (data->off + REC_SIZE > ps->size)
98 		return NULL;
99 
100 	(*pos)++;
101 	return data;
102 }
103 
104 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
105 {
106 	struct pstore_private *ps = s->private;
107 	struct pstore_ftrace_seq_data *data = v;
108 	struct pstore_ftrace_record *rec = (void *)(ps->data + data->off);
109 
110 	seq_printf(s, "%d %08lx  %08lx  %pf <- %pF\n",
111 		pstore_ftrace_decode_cpu(rec), rec->ip, rec->parent_ip,
112 		(void *)rec->ip, (void *)rec->parent_ip);
113 
114 	return 0;
115 }
116 
117 static const struct seq_operations pstore_ftrace_seq_ops = {
118 	.start	= pstore_ftrace_seq_start,
119 	.next	= pstore_ftrace_seq_next,
120 	.stop	= pstore_ftrace_seq_stop,
121 	.show	= pstore_ftrace_seq_show,
122 };
123 
124 static int pstore_check_syslog_permissions(struct pstore_private *ps)
125 {
126 	switch (ps->type) {
127 	case PSTORE_TYPE_DMESG:
128 	case PSTORE_TYPE_CONSOLE:
129 		return check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
130 			SYSLOG_FROM_READER);
131 	default:
132 		return 0;
133 	}
134 }
135 
136 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
137 						size_t count, loff_t *ppos)
138 {
139 	struct seq_file *sf = file->private_data;
140 	struct pstore_private *ps = sf->private;
141 
142 	if (ps->type == PSTORE_TYPE_FTRACE)
143 		return seq_read(file, userbuf, count, ppos);
144 	return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
145 }
146 
147 static int pstore_file_open(struct inode *inode, struct file *file)
148 {
149 	struct pstore_private *ps = inode->i_private;
150 	struct seq_file *sf;
151 	int err;
152 	const struct seq_operations *sops = NULL;
153 
154 	err = pstore_check_syslog_permissions(ps);
155 	if (err)
156 		return err;
157 
158 	if (ps->type == PSTORE_TYPE_FTRACE)
159 		sops = &pstore_ftrace_seq_ops;
160 
161 	err = seq_open(file, sops);
162 	if (err < 0)
163 		return err;
164 
165 	sf = file->private_data;
166 	sf->private = ps;
167 
168 	return 0;
169 }
170 
171 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
172 {
173 	struct seq_file *sf = file->private_data;
174 
175 	if (sf->op)
176 		return seq_lseek(file, off, whence);
177 	return default_llseek(file, off, whence);
178 }
179 
180 static const struct file_operations pstore_file_operations = {
181 	.owner		= THIS_MODULE,
182 	.open		= pstore_file_open,
183 	.read		= pstore_file_read,
184 	.llseek		= pstore_file_llseek,
185 	.release	= seq_release,
186 };
187 
188 /*
189  * When a file is unlinked from our file system we call the
190  * platform driver to erase the record from persistent store.
191  */
192 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
193 {
194 	struct pstore_private *p = d_inode(dentry)->i_private;
195 	int err;
196 
197 	err = pstore_check_syslog_permissions(p);
198 	if (err)
199 		return err;
200 
201 	if (p->psi->erase)
202 		p->psi->erase(p->type, p->id, p->count,
203 			      d_inode(dentry)->i_ctime, p->psi);
204 	else
205 		return -EPERM;
206 
207 	return simple_unlink(dir, dentry);
208 }
209 
210 static void pstore_evict_inode(struct inode *inode)
211 {
212 	struct pstore_private	*p = inode->i_private;
213 	unsigned long		flags;
214 
215 	clear_inode(inode);
216 	if (p) {
217 		spin_lock_irqsave(&allpstore_lock, flags);
218 		list_del(&p->list);
219 		spin_unlock_irqrestore(&allpstore_lock, flags);
220 		kfree(p);
221 	}
222 }
223 
224 static const struct inode_operations pstore_dir_inode_operations = {
225 	.lookup		= simple_lookup,
226 	.unlink		= pstore_unlink,
227 };
228 
229 static struct inode *pstore_get_inode(struct super_block *sb)
230 {
231 	struct inode *inode = new_inode(sb);
232 	if (inode) {
233 		inode->i_ino = get_next_ino();
234 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
235 	}
236 	return inode;
237 }
238 
239 enum {
240 	Opt_kmsg_bytes, Opt_err
241 };
242 
243 static const match_table_t tokens = {
244 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
245 	{Opt_err, NULL}
246 };
247 
248 static void parse_options(char *options)
249 {
250 	char		*p;
251 	substring_t	args[MAX_OPT_ARGS];
252 	int		option;
253 
254 	if (!options)
255 		return;
256 
257 	while ((p = strsep(&options, ",")) != NULL) {
258 		int token;
259 
260 		if (!*p)
261 			continue;
262 
263 		token = match_token(p, tokens, args);
264 		switch (token) {
265 		case Opt_kmsg_bytes:
266 			if (!match_int(&args[0], &option))
267 				pstore_set_kmsg_bytes(option);
268 			break;
269 		}
270 	}
271 }
272 
273 static int pstore_remount(struct super_block *sb, int *flags, char *data)
274 {
275 	sync_filesystem(sb);
276 	parse_options(data);
277 
278 	return 0;
279 }
280 
281 static const struct super_operations pstore_ops = {
282 	.statfs		= simple_statfs,
283 	.drop_inode	= generic_delete_inode,
284 	.evict_inode	= pstore_evict_inode,
285 	.remount_fs	= pstore_remount,
286 	.show_options	= generic_show_options,
287 };
288 
289 static struct super_block *pstore_sb;
290 
291 bool pstore_is_mounted(void)
292 {
293 	return pstore_sb != NULL;
294 }
295 
296 /*
297  * Make a regular file in the root directory of our file system.
298  * Load it up with "size" bytes of data from "buf".
299  * Set the mtime & ctime to the date that this record was originally stored.
300  */
301 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
302 		  char *data, bool compressed, size_t size,
303 		  struct timespec time, struct pstore_info *psi)
304 {
305 	struct dentry		*root = pstore_sb->s_root;
306 	struct dentry		*dentry;
307 	struct inode		*inode;
308 	int			rc = 0;
309 	char			name[PSTORE_NAMELEN];
310 	struct pstore_private	*private, *pos;
311 	unsigned long		flags;
312 
313 	spin_lock_irqsave(&allpstore_lock, flags);
314 	list_for_each_entry(pos, &allpstore, list) {
315 		if (pos->type == type &&
316 		    pos->id == id &&
317 		    pos->psi == psi) {
318 			rc = -EEXIST;
319 			break;
320 		}
321 	}
322 	spin_unlock_irqrestore(&allpstore_lock, flags);
323 	if (rc)
324 		return rc;
325 
326 	rc = -ENOMEM;
327 	inode = pstore_get_inode(pstore_sb);
328 	if (!inode)
329 		goto fail;
330 	inode->i_mode = S_IFREG | 0444;
331 	inode->i_fop = &pstore_file_operations;
332 	private = kmalloc(sizeof *private + size, GFP_KERNEL);
333 	if (!private)
334 		goto fail_alloc;
335 	private->type = type;
336 	private->id = id;
337 	private->count = count;
338 	private->psi = psi;
339 
340 	switch (type) {
341 	case PSTORE_TYPE_DMESG:
342 		scnprintf(name, sizeof(name), "dmesg-%s-%lld%s",
343 			  psname, id, compressed ? ".enc.z" : "");
344 		break;
345 	case PSTORE_TYPE_CONSOLE:
346 		scnprintf(name, sizeof(name), "console-%s-%lld", psname, id);
347 		break;
348 	case PSTORE_TYPE_FTRACE:
349 		scnprintf(name, sizeof(name), "ftrace-%s-%lld", psname, id);
350 		break;
351 	case PSTORE_TYPE_MCE:
352 		scnprintf(name, sizeof(name), "mce-%s-%lld", psname, id);
353 		break;
354 	case PSTORE_TYPE_PPC_RTAS:
355 		scnprintf(name, sizeof(name), "rtas-%s-%lld", psname, id);
356 		break;
357 	case PSTORE_TYPE_PPC_OF:
358 		scnprintf(name, sizeof(name), "powerpc-ofw-%s-%lld",
359 			  psname, id);
360 		break;
361 	case PSTORE_TYPE_PPC_COMMON:
362 		scnprintf(name, sizeof(name), "powerpc-common-%s-%lld",
363 			  psname, id);
364 		break;
365 	case PSTORE_TYPE_PMSG:
366 		scnprintf(name, sizeof(name), "pmsg-%s-%lld", psname, id);
367 		break;
368 	case PSTORE_TYPE_PPC_OPAL:
369 		sprintf(name, "powerpc-opal-%s-%lld", psname, id);
370 		break;
371 	case PSTORE_TYPE_UNKNOWN:
372 		scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
373 		break;
374 	default:
375 		scnprintf(name, sizeof(name), "type%d-%s-%lld",
376 			  type, psname, id);
377 		break;
378 	}
379 
380 	mutex_lock(&d_inode(root)->i_mutex);
381 
382 	dentry = d_alloc_name(root, name);
383 	if (!dentry)
384 		goto fail_lockedalloc;
385 
386 	memcpy(private->data, data, size);
387 	inode->i_size = private->size = size;
388 
389 	inode->i_private = private;
390 
391 	if (time.tv_sec)
392 		inode->i_mtime = inode->i_ctime = time;
393 
394 	d_add(dentry, inode);
395 
396 	spin_lock_irqsave(&allpstore_lock, flags);
397 	list_add(&private->list, &allpstore);
398 	spin_unlock_irqrestore(&allpstore_lock, flags);
399 
400 	mutex_unlock(&d_inode(root)->i_mutex);
401 
402 	return 0;
403 
404 fail_lockedalloc:
405 	mutex_unlock(&d_inode(root)->i_mutex);
406 	kfree(private);
407 fail_alloc:
408 	iput(inode);
409 
410 fail:
411 	return rc;
412 }
413 
414 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
415 {
416 	struct inode *inode;
417 
418 	save_mount_options(sb, data);
419 
420 	pstore_sb = sb;
421 
422 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
423 	sb->s_blocksize		= PAGE_CACHE_SIZE;
424 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
425 	sb->s_magic		= PSTOREFS_MAGIC;
426 	sb->s_op		= &pstore_ops;
427 	sb->s_time_gran		= 1;
428 
429 	parse_options(data);
430 
431 	inode = pstore_get_inode(sb);
432 	if (inode) {
433 		inode->i_mode = S_IFDIR | 0755;
434 		inode->i_op = &pstore_dir_inode_operations;
435 		inode->i_fop = &simple_dir_operations;
436 		inc_nlink(inode);
437 	}
438 	sb->s_root = d_make_root(inode);
439 	if (!sb->s_root)
440 		return -ENOMEM;
441 
442 	pstore_get_records(0);
443 
444 	return 0;
445 }
446 
447 static struct dentry *pstore_mount(struct file_system_type *fs_type,
448 	int flags, const char *dev_name, void *data)
449 {
450 	return mount_single(fs_type, flags, data, pstore_fill_super);
451 }
452 
453 static void pstore_kill_sb(struct super_block *sb)
454 {
455 	kill_litter_super(sb);
456 	pstore_sb = NULL;
457 }
458 
459 static struct file_system_type pstore_fs_type = {
460 	.owner          = THIS_MODULE,
461 	.name		= "pstore",
462 	.mount		= pstore_mount,
463 	.kill_sb	= pstore_kill_sb,
464 };
465 
466 static int __init init_pstore_fs(void)
467 {
468 	int err;
469 
470 	/* Create a convenient mount point for people to access pstore */
471 	err = sysfs_create_mount_point(fs_kobj, "pstore");
472 	if (err)
473 		goto out;
474 
475 	err = register_filesystem(&pstore_fs_type);
476 	if (err < 0)
477 		sysfs_remove_mount_point(fs_kobj, "pstore");
478 
479 out:
480 	return err;
481 }
482 module_init(init_pstore_fs)
483 
484 static void __exit exit_pstore_fs(void)
485 {
486 	unregister_filesystem(&pstore_fs_type);
487 	sysfs_remove_mount_point(fs_kobj, "pstore");
488 }
489 module_exit(exit_pstore_fs)
490 
491 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
492 MODULE_LICENSE("GPL");
493