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
45static DEFINE_SPINLOCK(allpstore_lock);
46static LIST_HEAD(allpstore);
47
48struct 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
58struct 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
66static 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
86static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
87{
88	kfree(v);
89}
90
91static 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
104static 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
117static 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
124static 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
136static 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
147static 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
171static 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
180static 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 */
191static int pstore_unlink(struct inode *dir, struct dentry *dentry)
192{
193	struct pstore_private *p = d_inode(dentry)->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			      d_inode(dentry)->i_ctime, p->psi);
203	else
204		return -EPERM;
205
206	return simple_unlink(dir, dentry);
207}
208
209static 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
223static const struct inode_operations pstore_dir_inode_operations = {
224	.lookup		= simple_lookup,
225	.unlink		= pstore_unlink,
226};
227
228static 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
238enum {
239	Opt_kmsg_bytes, Opt_err
240};
241
242static const match_table_t tokens = {
243	{Opt_kmsg_bytes, "kmsg_bytes=%u"},
244	{Opt_err, NULL}
245};
246
247static 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
272static 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
280static 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
288static struct super_block *pstore_sb;
289
290int 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 */
300int 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		scnprintf(name, sizeof(name), "dmesg-%s-%lld%s",
342			  psname, id, compressed ? ".enc.z" : "");
343		break;
344	case PSTORE_TYPE_CONSOLE:
345		scnprintf(name, sizeof(name), "console-%s-%lld", psname, id);
346		break;
347	case PSTORE_TYPE_FTRACE:
348		scnprintf(name, sizeof(name), "ftrace-%s-%lld", psname, id);
349		break;
350	case PSTORE_TYPE_MCE:
351		scnprintf(name, sizeof(name), "mce-%s-%lld", psname, id);
352		break;
353	case PSTORE_TYPE_PPC_RTAS:
354		scnprintf(name, sizeof(name), "rtas-%s-%lld", psname, id);
355		break;
356	case PSTORE_TYPE_PPC_OF:
357		scnprintf(name, sizeof(name), "powerpc-ofw-%s-%lld",
358			  psname, id);
359		break;
360	case PSTORE_TYPE_PPC_COMMON:
361		scnprintf(name, sizeof(name), "powerpc-common-%s-%lld",
362			  psname, id);
363		break;
364	case PSTORE_TYPE_PMSG:
365		scnprintf(name, sizeof(name), "pmsg-%s-%lld", psname, id);
366		break;
367	case PSTORE_TYPE_PPC_OPAL:
368		sprintf(name, "powerpc-opal-%s-%lld", psname, id);
369		break;
370	case PSTORE_TYPE_UNKNOWN:
371		scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
372		break;
373	default:
374		scnprintf(name, sizeof(name), "type%d-%s-%lld",
375			  type, psname, id);
376		break;
377	}
378
379	mutex_lock(&d_inode(root)->i_mutex);
380
381	dentry = d_alloc_name(root, name);
382	if (!dentry)
383		goto fail_lockedalloc;
384
385	memcpy(private->data, data, size);
386	inode->i_size = private->size = size;
387
388	inode->i_private = private;
389
390	if (time.tv_sec)
391		inode->i_mtime = inode->i_ctime = time;
392
393	d_add(dentry, inode);
394
395	spin_lock_irqsave(&allpstore_lock, flags);
396	list_add(&private->list, &allpstore);
397	spin_unlock_irqrestore(&allpstore_lock, flags);
398
399	mutex_unlock(&d_inode(root)->i_mutex);
400
401	return 0;
402
403fail_lockedalloc:
404	mutex_unlock(&d_inode(root)->i_mutex);
405	kfree(private);
406fail_alloc:
407	iput(inode);
408
409fail:
410	return rc;
411}
412
413static int pstore_fill_super(struct super_block *sb, void *data, int silent)
414{
415	struct inode *inode;
416
417	save_mount_options(sb, data);
418
419	pstore_sb = sb;
420
421	sb->s_maxbytes		= MAX_LFS_FILESIZE;
422	sb->s_blocksize		= PAGE_CACHE_SIZE;
423	sb->s_blocksize_bits	= PAGE_CACHE_SHIFT;
424	sb->s_magic		= PSTOREFS_MAGIC;
425	sb->s_op		= &pstore_ops;
426	sb->s_time_gran		= 1;
427
428	parse_options(data);
429
430	inode = pstore_get_inode(sb);
431	if (inode) {
432		inode->i_mode = S_IFDIR | 0755;
433		inode->i_op = &pstore_dir_inode_operations;
434		inode->i_fop = &simple_dir_operations;
435		inc_nlink(inode);
436	}
437	sb->s_root = d_make_root(inode);
438	if (!sb->s_root)
439		return -ENOMEM;
440
441	pstore_get_records(0);
442
443	return 0;
444}
445
446static struct dentry *pstore_mount(struct file_system_type *fs_type,
447	int flags, const char *dev_name, void *data)
448{
449	return mount_single(fs_type, flags, data, pstore_fill_super);
450}
451
452static void pstore_kill_sb(struct super_block *sb)
453{
454	kill_litter_super(sb);
455	pstore_sb = NULL;
456}
457
458static struct file_system_type pstore_fs_type = {
459	.name		= "pstore",
460	.mount		= pstore_mount,
461	.kill_sb	= pstore_kill_sb,
462};
463
464static int __init init_pstore_fs(void)
465{
466	int err;
467
468	/* Create a convenient mount point for people to access pstore */
469	err = sysfs_create_mount_point(fs_kobj, "pstore");
470	if (err)
471		goto out;
472
473	err = register_filesystem(&pstore_fs_type);
474	if (err < 0)
475		sysfs_remove_mount_point(fs_kobj, "pstore");
476
477out:
478	return err;
479}
480module_init(init_pstore_fs)
481
482MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
483MODULE_LICENSE("GPL");
484