xref: /openbmc/linux/fs/pstore/inode.c (revision 4161b450) 
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 	.open		= pstore_file_open,
182 	.read		= pstore_file_read,
183 	.llseek		= pstore_file_llseek,
184 	.release	= seq_release,
185 };
186 
187 /*
188  * When a file is unlinked from our file system we call the
189  * platform driver to erase the record from persistent store.
190  */
191 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
192 {
193 	struct pstore_private *p = dentry->d_inode->i_private;
194 	int err;
195 
196 	err = pstore_check_syslog_permissions(p);
197 	if (err)
198 		return err;
199 
200 	if (p->psi->erase)
201 		p->psi->erase(p->type, p->id, p->count,
202 			      dentry->d_inode->i_ctime, p->psi);
203 	else
204 		return -EPERM;
205 
206 	return simple_unlink(dir, dentry);
207 }
208 
209 static void pstore_evict_inode(struct inode *inode)
210 {
211 	struct pstore_private	*p = inode->i_private;
212 	unsigned long		flags;
213 
214 	clear_inode(inode);
215 	if (p) {
216 		spin_lock_irqsave(&allpstore_lock, flags);
217 		list_del(&p->list);
218 		spin_unlock_irqrestore(&allpstore_lock, flags);
219 		kfree(p);
220 	}
221 }
222 
223 static const struct inode_operations pstore_dir_inode_operations = {
224 	.lookup		= simple_lookup,
225 	.unlink		= pstore_unlink,
226 };
227 
228 static struct inode *pstore_get_inode(struct super_block *sb)
229 {
230 	struct inode *inode = new_inode(sb);
231 	if (inode) {
232 		inode->i_ino = get_next_ino();
233 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
234 	}
235 	return inode;
236 }
237 
238 enum {
239 	Opt_kmsg_bytes, Opt_err
240 };
241 
242 static const match_table_t tokens = {
243 	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
244 	{Opt_err, NULL}
245 };
246 
247 static void parse_options(char *options)
248 {
249 	char		*p;
250 	substring_t	args[MAX_OPT_ARGS];
251 	int		option;
252 
253 	if (!options)
254 		return;
255 
256 	while ((p = strsep(&options, ",")) != NULL) {
257 		int token;
258 
259 		if (!*p)
260 			continue;
261 
262 		token = match_token(p, tokens, args);
263 		switch (token) {
264 		case Opt_kmsg_bytes:
265 			if (!match_int(&args[0], &option))
266 				pstore_set_kmsg_bytes(option);
267 			break;
268 		}
269 	}
270 }
271 
272 static int pstore_remount(struct super_block *sb, int *flags, char *data)
273 {
274 	sync_filesystem(sb);
275 	parse_options(data);
276 
277 	return 0;
278 }
279 
280 static const struct super_operations pstore_ops = {
281 	.statfs		= simple_statfs,
282 	.drop_inode	= generic_delete_inode,
283 	.evict_inode	= pstore_evict_inode,
284 	.remount_fs	= pstore_remount,
285 	.show_options	= generic_show_options,
286 };
287 
288 static struct super_block *pstore_sb;
289 
290 int pstore_is_mounted(void)
291 {
292 	return pstore_sb != NULL;
293 }
294 
295 /*
296  * Make a regular file in the root directory of our file system.
297  * Load it up with "size" bytes of data from "buf".
298  * Set the mtime & ctime to the date that this record was originally stored.
299  */
300 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
301 		  char *data, bool compressed, size_t size,
302 		  struct timespec time, struct pstore_info *psi)
303 {
304 	struct dentry		*root = pstore_sb->s_root;
305 	struct dentry		*dentry;
306 	struct inode		*inode;
307 	int			rc = 0;
308 	char			name[PSTORE_NAMELEN];
309 	struct pstore_private	*private, *pos;
310 	unsigned long		flags;
311 
312 	spin_lock_irqsave(&allpstore_lock, flags);
313 	list_for_each_entry(pos, &allpstore, list) {
314 		if (pos->type == type &&
315 		    pos->id == id &&
316 		    pos->psi == psi) {
317 			rc = -EEXIST;
318 			break;
319 		}
320 	}
321 	spin_unlock_irqrestore(&allpstore_lock, flags);
322 	if (rc)
323 		return rc;
324 
325 	rc = -ENOMEM;
326 	inode = pstore_get_inode(pstore_sb);
327 	if (!inode)
328 		goto fail;
329 	inode->i_mode = S_IFREG | 0444;
330 	inode->i_fop = &pstore_file_operations;
331 	private = kmalloc(sizeof *private + size, GFP_KERNEL);
332 	if (!private)
333 		goto fail_alloc;
334 	private->type = type;
335 	private->id = id;
336 	private->count = count;
337 	private->psi = psi;
338 
339 	switch (type) {
340 	case PSTORE_TYPE_DMESG:
341 		sprintf(name, "dmesg-%s-%lld%s", psname, id,
342 						compressed ? ".enc.z" : "");
343 		break;
344 	case PSTORE_TYPE_CONSOLE:
345 		sprintf(name, "console-%s-%lld", psname, id);
346 		break;
347 	case PSTORE_TYPE_FTRACE:
348 		sprintf(name, "ftrace-%s-%lld", psname, id);
349 		break;
350 	case PSTORE_TYPE_MCE:
351 		sprintf(name, "mce-%s-%lld", psname, id);
352 		break;
353 	case PSTORE_TYPE_PPC_RTAS:
354 		sprintf(name, "rtas-%s-%lld", psname, id);
355 		break;
356 	case PSTORE_TYPE_PPC_OF:
357 		sprintf(name, "powerpc-ofw-%s-%lld", psname, id);
358 		break;
359 	case PSTORE_TYPE_PPC_COMMON:
360 		sprintf(name, "powerpc-common-%s-%lld", psname, id);
361 		break;
362 	case PSTORE_TYPE_UNKNOWN:
363 		sprintf(name, "unknown-%s-%lld", psname, id);
364 		break;
365 	default:
366 		sprintf(name, "type%d-%s-%lld", type, psname, id);
367 		break;
368 	}
369 
370 	mutex_lock(&root->d_inode->i_mutex);
371 
372 	dentry = d_alloc_name(root, name);
373 	if (!dentry)
374 		goto fail_lockedalloc;
375 
376 	memcpy(private->data, data, size);
377 	inode->i_size = private->size = size;
378 
379 	inode->i_private = private;
380 
381 	if (time.tv_sec)
382 		inode->i_mtime = inode->i_ctime = time;
383 
384 	d_add(dentry, inode);
385 
386 	spin_lock_irqsave(&allpstore_lock, flags);
387 	list_add(&private->list, &allpstore);
388 	spin_unlock_irqrestore(&allpstore_lock, flags);
389 
390 	mutex_unlock(&root->d_inode->i_mutex);
391 
392 	return 0;
393 
394 fail_lockedalloc:
395 	mutex_unlock(&root->d_inode->i_mutex);
396 	kfree(private);
397 fail_alloc:
398 	iput(inode);
399 
400 fail:
401 	return rc;
402 }
403 
404 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
405 {
406 	struct inode *inode;
407 
408 	save_mount_options(sb, data);
409 
410 	pstore_sb = sb;
411 
412 	sb->s_maxbytes		= MAX_LFS_FILESIZE;
413 	sb->s_blocksize		= PAGE_CACHE_SIZE;
414 	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
415 	sb->s_magic		= PSTOREFS_MAGIC;
416 	sb->s_op		= &pstore_ops;
417 	sb->s_time_gran		= 1;
418 
419 	parse_options(data);
420 
421 	inode = pstore_get_inode(sb);
422 	if (inode) {
423 		inode->i_mode = S_IFDIR | 0755;
424 		inode->i_op = &pstore_dir_inode_operations;
425 		inode->i_fop = &simple_dir_operations;
426 		inc_nlink(inode);
427 	}
428 	sb->s_root = d_make_root(inode);
429 	if (!sb->s_root)
430 		return -ENOMEM;
431 
432 	pstore_get_records(0);
433 
434 	return 0;
435 }
436 
437 static struct dentry *pstore_mount(struct file_system_type *fs_type,
438 	int flags, const char *dev_name, void *data)
439 {
440 	return mount_single(fs_type, flags, data, pstore_fill_super);
441 }
442 
443 static void pstore_kill_sb(struct super_block *sb)
444 {
445 	kill_litter_super(sb);
446 	pstore_sb = NULL;
447 }
448 
449 static struct file_system_type pstore_fs_type = {
450 	.name		= "pstore",
451 	.mount		= pstore_mount,
452 	.kill_sb	= pstore_kill_sb,
453 };
454 
455 static struct kobject *pstore_kobj;
456 
457 static int __init init_pstore_fs(void)
458 {
459 	int err = 0;
460 
461 	/* Create a convenient mount point for people to access pstore */
462 	pstore_kobj = kobject_create_and_add("pstore", fs_kobj);
463 	if (!pstore_kobj) {
464 		err = -ENOMEM;
465 		goto out;
466 	}
467 
468 	err = register_filesystem(&pstore_fs_type);
469 	if (err < 0)
470 		kobject_put(pstore_kobj);
471 
472 out:
473 	return err;
474 }
475 module_init(init_pstore_fs)
476 
477 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
478 MODULE_LICENSE("GPL");
479