xref: /openbmc/linux/fs/pstore/inode.c (revision 8730046c) 
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, "CPU:%d ts:%llu %08lx  %08lx  %pf <- %pF\n",
111 		   pstore_ftrace_decode_cpu(rec),
112 		   pstore_ftrace_read_timestamp(rec),
113 		   rec->ip, rec->parent_ip, (void *)rec->ip,
114 		   (void *)rec->parent_ip);
115 
116 	return 0;
117 }
118 
119 static const struct seq_operations pstore_ftrace_seq_ops = {
120 	.start	= pstore_ftrace_seq_start,
121 	.next	= pstore_ftrace_seq_next,
122 	.stop	= pstore_ftrace_seq_stop,
123 	.show	= pstore_ftrace_seq_show,
124 };
125 
126 static int pstore_check_syslog_permissions(struct pstore_private *ps)
127 {
128 	switch (ps->type) {
129 	case PSTORE_TYPE_DMESG:
130 	case PSTORE_TYPE_CONSOLE:
131 		return check_syslog_permissions(SYSLOG_ACTION_READ_ALL,
132 			SYSLOG_FROM_READER);
133 	default:
134 		return 0;
135 	}
136 }
137 
138 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
139 						size_t count, loff_t *ppos)
140 {
141 	struct seq_file *sf = file->private_data;
142 	struct pstore_private *ps = sf->private;
143 
144 	if (ps->type == PSTORE_TYPE_FTRACE)
145 		return seq_read(file, userbuf, count, ppos);
146 	return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
147 }
148 
149 static int pstore_file_open(struct inode *inode, struct file *file)
150 {
151 	struct pstore_private *ps = inode->i_private;
152 	struct seq_file *sf;
153 	int err;
154 	const struct seq_operations *sops = NULL;
155 
156 	err = pstore_check_syslog_permissions(ps);
157 	if (err)
158 		return err;
159 
160 	if (ps->type == PSTORE_TYPE_FTRACE)
161 		sops = &pstore_ftrace_seq_ops;
162 
163 	err = seq_open(file, sops);
164 	if (err < 0)
165 		return err;
166 
167 	sf = file->private_data;
168 	sf->private = ps;
169 
170 	return 0;
171 }
172 
173 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
174 {
175 	struct seq_file *sf = file->private_data;
176 
177 	if (sf->op)
178 		return seq_lseek(file, off, whence);
179 	return default_llseek(file, off, whence);
180 }
181 
182 static const struct file_operations pstore_file_operations = {
183 	.open		= pstore_file_open,
184 	.read		= pstore_file_read,
185 	.llseek		= pstore_file_llseek,
186 	.release	= seq_release,
187 };
188 
189 /*
190  * When a file is unlinked from our file system we call the
191  * platform driver to erase the record from persistent store.
192  */
193 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
194 {
195 	struct pstore_private *p = d_inode(dentry)->i_private;
196 	int err;
197 
198 	err = pstore_check_syslog_permissions(p);
199 	if (err)
200 		return err;
201 
202 	if (p->psi->erase) {
203 		mutex_lock(&p->psi->read_mutex);
204 		p->psi->erase(p->type, p->id, p->count,
205 			      d_inode(dentry)->i_ctime, p->psi);
206 		mutex_unlock(&p->psi->read_mutex);
207 	} else {
208 		return -EPERM;
209 	}
210 
211 	return simple_unlink(dir, dentry);
212 }
213 
214 static void pstore_evict_inode(struct inode *inode)
215 {
216 	struct pstore_private	*p = inode->i_private;
217 	unsigned long		flags;
218 
219 	clear_inode(inode);
220 	if (p) {
221 		spin_lock_irqsave(&allpstore_lock, flags);
222 		list_del(&p->list);
223 		spin_unlock_irqrestore(&allpstore_lock, flags);
224 		kfree(p);
225 	}
226 }
227 
228 static const struct inode_operations pstore_dir_inode_operations = {
229 	.lookup		= simple_lookup,
230 	.unlink		= pstore_unlink,
231 };
232 
233 static struct inode *pstore_get_inode(struct super_block *sb)
234 {
235 	struct inode *inode = new_inode(sb);
236 	if (inode) {
237 		inode->i_ino = get_next_ino();
238 		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
239 	}
240 	return inode;
241 }
242 
243 enum {
244 	Opt_kmsg_bytes, Opt_err
245 };
246 
247 static const match_table_t tokens = {
248 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
249 	{Opt_err, NULL}
250 };
251 
252 static void parse_options(char *options)
253 {
254 	char		*p;
255 	substring_t	args[MAX_OPT_ARGS];
256 	int		option;
257 
258 	if (!options)
259 		return;
260 
261 	while ((p = strsep(&options, ",")) != NULL) {
262 		int token;
263 
264 		if (!*p)
265 			continue;
266 
267 		token = match_token(p, tokens, args);
268 		switch (token) {
269 		case Opt_kmsg_bytes:
270 			if (!match_int(&args[0], &option))
271 				pstore_set_kmsg_bytes(option);
272 			break;
273 		}
274 	}
275 }
276 
277 static int pstore_remount(struct super_block *sb, int *flags, char *data)
278 {
279 	sync_filesystem(sb);
280 	parse_options(data);
281 
282 	return 0;
283 }
284 
285 static const struct super_operations pstore_ops = {
286 	.statfs		= simple_statfs,
287 	.drop_inode	= generic_delete_inode,
288 	.evict_inode	= pstore_evict_inode,
289 	.remount_fs	= pstore_remount,
290 	.show_options	= generic_show_options,
291 };
292 
293 static struct super_block *pstore_sb;
294 
295 bool pstore_is_mounted(void)
296 {
297 	return pstore_sb != NULL;
298 }
299 
300 /*
301  * Make a regular file in the root directory of our file system.
302  * Load it up with "size" bytes of data from "buf".
303  * Set the mtime & ctime to the date that this record was originally stored.
304  */
305 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
306 		  char *data, bool compressed, size_t size,
307 		  struct timespec time, struct pstore_info *psi)
308 {
309 	struct dentry		*root = pstore_sb->s_root;
310 	struct dentry		*dentry;
311 	struct inode		*inode;
312 	int			rc = 0;
313 	char			name[PSTORE_NAMELEN];
314 	struct pstore_private	*private, *pos;
315 	unsigned long		flags;
316 
317 	spin_lock_irqsave(&allpstore_lock, flags);
318 	list_for_each_entry(pos, &allpstore, list) {
319 		if (pos->type == type &&
320 		    pos->id == id &&
321 		    pos->psi == psi) {
322 			rc = -EEXIST;
323 			break;
324 		}
325 	}
326 	spin_unlock_irqrestore(&allpstore_lock, flags);
327 	if (rc)
328 		return rc;
329 
330 	rc = -ENOMEM;
331 	inode = pstore_get_inode(pstore_sb);
332 	if (!inode)
333 		goto fail;
334 	inode->i_mode = S_IFREG | 0444;
335 	inode->i_fop = &pstore_file_operations;
336 	private = kmalloc(sizeof *private + size, GFP_KERNEL);
337 	if (!private)
338 		goto fail_alloc;
339 	private->type = type;
340 	private->id = id;
341 	private->count = count;
342 	private->psi = psi;
343 
344 	switch (type) {
345 	case PSTORE_TYPE_DMESG:
346 		scnprintf(name, sizeof(name), "dmesg-%s-%lld%s",
347 			  psname, id, compressed ? ".enc.z" : "");
348 		break;
349 	case PSTORE_TYPE_CONSOLE:
350 		scnprintf(name, sizeof(name), "console-%s-%lld", psname, id);
351 		break;
352 	case PSTORE_TYPE_FTRACE:
353 		scnprintf(name, sizeof(name), "ftrace-%s-%lld", psname, id);
354 		break;
355 	case PSTORE_TYPE_MCE:
356 		scnprintf(name, sizeof(name), "mce-%s-%lld", psname, id);
357 		break;
358 	case PSTORE_TYPE_PPC_RTAS:
359 		scnprintf(name, sizeof(name), "rtas-%s-%lld", psname, id);
360 		break;
361 	case PSTORE_TYPE_PPC_OF:
362 		scnprintf(name, sizeof(name), "powerpc-ofw-%s-%lld",
363 			  psname, id);
364 		break;
365 	case PSTORE_TYPE_PPC_COMMON:
366 		scnprintf(name, sizeof(name), "powerpc-common-%s-%lld",
367 			  psname, id);
368 		break;
369 	case PSTORE_TYPE_PMSG:
370 		scnprintf(name, sizeof(name), "pmsg-%s-%lld", psname, id);
371 		break;
372 	case PSTORE_TYPE_PPC_OPAL:
373 		sprintf(name, "powerpc-opal-%s-%lld", psname, id);
374 		break;
375 	case PSTORE_TYPE_UNKNOWN:
376 		scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
377 		break;
378 	default:
379 		scnprintf(name, sizeof(name), "type%d-%s-%lld",
380 			  type, psname, id);
381 		break;
382 	}
383 
384 	inode_lock(d_inode(root));
385 
386 	dentry = d_alloc_name(root, name);
387 	if (!dentry)
388 		goto fail_lockedalloc;
389 
390 	memcpy(private->data, data, size);
391 	inode->i_size = private->size = size;
392 
393 	inode->i_private = private;
394 
395 	if (time.tv_sec)
396 		inode->i_mtime = inode->i_ctime = time;
397 
398 	d_add(dentry, inode);
399 
400 	spin_lock_irqsave(&allpstore_lock, flags);
401 	list_add(&private->list, &allpstore);
402 	spin_unlock_irqrestore(&allpstore_lock, flags);
403 
404 	inode_unlock(d_inode(root));
405 
406 	return 0;
407 
408 fail_lockedalloc:
409 	inode_unlock(d_inode(root));
410 	kfree(private);
411 fail_alloc:
412 	iput(inode);
413 
414 fail:
415 	return rc;
416 }
417 
418 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
419 {
420 	struct inode *inode;
421 
422 	save_mount_options(sb, data);
423 
424 	pstore_sb = sb;
425 
426 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
427 	sb->s_blocksize		= PAGE_SIZE;
428 	sb->s_blocksize_bits	= PAGE_SHIFT;
429 	sb->s_magic		= PSTOREFS_MAGIC;
430 	sb->s_op		= &pstore_ops;
431 	sb->s_time_gran		= 1;
432 
433 	parse_options(data);
434 
435 	inode = pstore_get_inode(sb);
436 	if (inode) {
437 		inode->i_mode = S_IFDIR | 0755;
438 		inode->i_op = &pstore_dir_inode_operations;
439 		inode->i_fop = &simple_dir_operations;
440 		inc_nlink(inode);
441 	}
442 	sb->s_root = d_make_root(inode);
443 	if (!sb->s_root)
444 		return -ENOMEM;
445 
446 	pstore_get_records(0);
447 
448 	return 0;
449 }
450 
451 static struct dentry *pstore_mount(struct file_system_type *fs_type,
452 	int flags, const char *dev_name, void *data)
453 {
454 	return mount_single(fs_type, flags, data, pstore_fill_super);
455 }
456 
457 static void pstore_kill_sb(struct super_block *sb)
458 {
459 	kill_litter_super(sb);
460 	pstore_sb = NULL;
461 }
462 
463 static struct file_system_type pstore_fs_type = {
464 	.owner          = THIS_MODULE,
465 	.name		= "pstore",
466 	.mount		= pstore_mount,
467 	.kill_sb	= pstore_kill_sb,
468 };
469 
470 static int __init init_pstore_fs(void)
471 {
472 	int err;
473 
474 	/* Create a convenient mount point for people to access pstore */
475 	err = sysfs_create_mount_point(fs_kobj, "pstore");
476 	if (err)
477 		goto out;
478 
479 	err = register_filesystem(&pstore_fs_type);
480 	if (err < 0)
481 		sysfs_remove_mount_point(fs_kobj, "pstore");
482 
483 out:
484 	return err;
485 }
486 module_init(init_pstore_fs)
487 
488 static void __exit exit_pstore_fs(void)
489 {
490 	unregister_filesystem(&pstore_fs_type);
491 	sysfs_remove_mount_point(fs_kobj, "pstore");
492 }
493 module_exit(exit_pstore_fs)
494 
495 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
496 MODULE_LICENSE("GPL");
497