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
40 #include "internal.h"
41
42 #define PSTORE_NAMELEN 64
43
44 static DEFINE_SPINLOCK(allpstore_lock);
45 static LIST_HEAD(allpstore);
46
47 struct pstore_private {
48 struct list_head list;
49 struct pstore_info *psi;
50 enum pstore_type_id type;
51 u64 id;
52 int count;
53 ssize_t size;
54 char data[];
55 };
56
57 struct pstore_ftrace_seq_data {
58 const void *ptr;
59 size_t off;
60 size_t size;
61 };
62
63 #define REC_SIZE sizeof(struct pstore_ftrace_record)
64
pstore_ftrace_seq_start(struct seq_file * s,loff_t * pos)65 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
66 {
67 struct pstore_private *ps = s->private;
68 struct pstore_ftrace_seq_data *data;
69
70 data = kzalloc(sizeof(*data), GFP_KERNEL);
71 if (!data)
72 return NULL;
73
74 data->off = ps->size % REC_SIZE;
75 data->off += *pos * REC_SIZE;
76 if (data->off + REC_SIZE > ps->size) {
77 kfree(data);
78 return NULL;
79 }
80
81 return data;
82
83 }
84
pstore_ftrace_seq_stop(struct seq_file * s,void * v)85 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
86 {
87 kfree(v);
88 }
89
pstore_ftrace_seq_next(struct seq_file * s,void * v,loff_t * pos)90 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
91 {
92 struct pstore_private *ps = s->private;
93 struct pstore_ftrace_seq_data *data = v;
94
95 data->off += REC_SIZE;
96 if (data->off + REC_SIZE > ps->size)
97 return NULL;
98
99 (*pos)++;
100 return data;
101 }
102
pstore_ftrace_seq_show(struct seq_file * s,void * v)103 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
104 {
105 struct pstore_private *ps = s->private;
106 struct pstore_ftrace_seq_data *data = v;
107 struct pstore_ftrace_record *rec = (void *)(ps->data + data->off);
108
109 seq_printf(s, "%d %08lx %08lx %pf <- %pF\n",
110 pstore_ftrace_decode_cpu(rec), rec->ip, rec->parent_ip,
111 (void *)rec->ip, (void *)rec->parent_ip);
112
113 return 0;
114 }
115
116 static const struct seq_operations pstore_ftrace_seq_ops = {
117 .start = pstore_ftrace_seq_start,
118 .next = pstore_ftrace_seq_next,
119 .stop = pstore_ftrace_seq_stop,
120 .show = pstore_ftrace_seq_show,
121 };
122
pstore_file_read(struct file * file,char __user * userbuf,size_t count,loff_t * ppos)123 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
124 size_t count, loff_t *ppos)
125 {
126 struct seq_file *sf = file->private_data;
127 struct pstore_private *ps = sf->private;
128
129 if (ps->type == PSTORE_TYPE_FTRACE)
130 return seq_read(file, userbuf, count, ppos);
131 return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
132 }
133
pstore_file_open(struct inode * inode,struct file * file)134 static int pstore_file_open(struct inode *inode, struct file *file)
135 {
136 struct pstore_private *ps = inode->i_private;
137 struct seq_file *sf;
138 int err;
139 const struct seq_operations *sops = NULL;
140
141 if (ps->type == PSTORE_TYPE_FTRACE)
142 sops = &pstore_ftrace_seq_ops;
143
144 err = seq_open(file, sops);
145 if (err < 0)
146 return err;
147
148 sf = file->private_data;
149 sf->private = ps;
150
151 return 0;
152 }
153
pstore_file_llseek(struct file * file,loff_t off,int whence)154 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
155 {
156 struct seq_file *sf = file->private_data;
157
158 if (sf->op)
159 return seq_lseek(file, off, whence);
160 return default_llseek(file, off, whence);
161 }
162
163 static const struct file_operations pstore_file_operations = {
164 .open = pstore_file_open,
165 .read = pstore_file_read,
166 .llseek = pstore_file_llseek,
167 .release = seq_release,
168 };
169
170 /*
171 * When a file is unlinked from our file system we call the
172 * platform driver to erase the record from persistent store.
173 */
pstore_unlink(struct inode * dir,struct dentry * dentry)174 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
175 {
176 struct pstore_private *p = dentry->d_inode->i_private;
177
178 if (p->psi->erase)
179 p->psi->erase(p->type, p->id, p->count,
180 dentry->d_inode->i_ctime, p->psi);
181
182 return simple_unlink(dir, dentry);
183 }
184
pstore_evict_inode(struct inode * inode)185 static void pstore_evict_inode(struct inode *inode)
186 {
187 struct pstore_private *p = inode->i_private;
188 unsigned long flags;
189
190 clear_inode(inode);
191 if (p) {
192 spin_lock_irqsave(&allpstore_lock, flags);
193 list_del(&p->list);
194 spin_unlock_irqrestore(&allpstore_lock, flags);
195 kfree(p);
196 }
197 }
198
199 static const struct inode_operations pstore_dir_inode_operations = {
200 .lookup = simple_lookup,
201 .unlink = pstore_unlink,
202 };
203
pstore_get_inode(struct super_block * sb)204 static struct inode *pstore_get_inode(struct super_block *sb)
205 {
206 struct inode *inode = new_inode(sb);
207 if (inode) {
208 inode->i_ino = get_next_ino();
209 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
210 }
211 return inode;
212 }
213
214 enum {
215 Opt_kmsg_bytes, Opt_err
216 };
217
218 static const match_table_t tokens = {
219 {Opt_kmsg_bytes, "kmsg_bytes=%u"},
220 {Opt_err, NULL}
221 };
222
parse_options(char * options)223 static void parse_options(char *options)
224 {
225 char *p;
226 substring_t args[MAX_OPT_ARGS];
227 int option;
228
229 if (!options)
230 return;
231
232 while ((p = strsep(&options, ",")) != NULL) {
233 int token;
234
235 if (!*p)
236 continue;
237
238 token = match_token(p, tokens, args);
239 switch (token) {
240 case Opt_kmsg_bytes:
241 if (!match_int(&args[0], &option))
242 pstore_set_kmsg_bytes(option);
243 break;
244 }
245 }
246 }
247
pstore_remount(struct super_block * sb,int * flags,char * data)248 static int pstore_remount(struct super_block *sb, int *flags, char *data)
249 {
250 sync_filesystem(sb);
251 parse_options(data);
252
253 return 0;
254 }
255
256 static const struct super_operations pstore_ops = {
257 .statfs = simple_statfs,
258 .drop_inode = generic_delete_inode,
259 .evict_inode = pstore_evict_inode,
260 .remount_fs = pstore_remount,
261 .show_options = generic_show_options,
262 };
263
264 static struct super_block *pstore_sb;
265
pstore_is_mounted(void)266 int pstore_is_mounted(void)
267 {
268 return pstore_sb != NULL;
269 }
270
271 /*
272 * Make a regular file in the root directory of our file system.
273 * Load it up with "size" bytes of data from "buf".
274 * Set the mtime & ctime to the date that this record was originally stored.
275 */
pstore_mkfile(enum pstore_type_id type,char * psname,u64 id,int count,char * data,size_t size,struct timespec time,struct pstore_info * psi)276 int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id, int count,
277 char *data, size_t size, struct timespec time,
278 struct pstore_info *psi)
279 {
280 struct dentry *root = pstore_sb->s_root;
281 struct dentry *dentry;
282 struct inode *inode;
283 int rc = 0;
284 char name[PSTORE_NAMELEN];
285 struct pstore_private *private, *pos;
286 unsigned long flags;
287
288 spin_lock_irqsave(&allpstore_lock, flags);
289 list_for_each_entry(pos, &allpstore, list) {
290 if (pos->type == type &&
291 pos->id == id &&
292 pos->psi == psi) {
293 rc = -EEXIST;
294 break;
295 }
296 }
297 spin_unlock_irqrestore(&allpstore_lock, flags);
298 if (rc)
299 return rc;
300
301 rc = -ENOMEM;
302 inode = pstore_get_inode(pstore_sb);
303 if (!inode)
304 goto fail;
305 inode->i_mode = S_IFREG | 0444;
306 inode->i_fop = &pstore_file_operations;
307 private = kmalloc(sizeof *private + size, GFP_KERNEL);
308 if (!private)
309 goto fail_alloc;
310 private->type = type;
311 private->id = id;
312 private->count = count;
313 private->psi = psi;
314
315 switch (type) {
316 case PSTORE_TYPE_DMESG:
317 scnprintf(name, sizeof(name), "dmesg-%s-%lld",
318 psname, id);
319 break;
320 case PSTORE_TYPE_CONSOLE:
321 scnprintf(name, sizeof(name), "console-%s", psname);
322 break;
323 case PSTORE_TYPE_FTRACE:
324 scnprintf(name, sizeof(name), "ftrace-%s", psname);
325 break;
326 case PSTORE_TYPE_MCE:
327 scnprintf(name, sizeof(name), "mce-%s-%lld", psname, id);
328 break;
329 case PSTORE_TYPE_PMSG:
330 scnprintf(name, sizeof(name), "pmsg-%s-%lld", psname, id);
331 break;
332 case PSTORE_TYPE_UNKNOWN:
333 scnprintf(name, sizeof(name), "unknown-%s-%lld", psname, id);
334 break;
335 default:
336 scnprintf(name, sizeof(name), "type%d-%s-%lld",
337 type, psname, id);
338 break;
339 }
340
341 mutex_lock(&root->d_inode->i_mutex);
342
343 rc = -ENOSPC;
344 dentry = d_alloc_name(root, name);
345 if (IS_ERR(dentry))
346 goto fail_lockedalloc;
347
348 memcpy(private->data, data, size);
349 inode->i_size = private->size = size;
350
351 inode->i_private = private;
352
353 if (time.tv_sec)
354 inode->i_mtime = inode->i_ctime = time;
355
356 d_add(dentry, inode);
357
358 spin_lock_irqsave(&allpstore_lock, flags);
359 list_add(&private->list, &allpstore);
360 spin_unlock_irqrestore(&allpstore_lock, flags);
361
362 mutex_unlock(&root->d_inode->i_mutex);
363
364 return 0;
365
366 fail_lockedalloc:
367 mutex_unlock(&root->d_inode->i_mutex);
368 kfree(private);
369 fail_alloc:
370 iput(inode);
371
372 fail:
373 return rc;
374 }
375
pstore_fill_super(struct super_block * sb,void * data,int silent)376 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
377 {
378 struct inode *inode;
379
380 save_mount_options(sb, data);
381
382 pstore_sb = sb;
383
384 sb->s_maxbytes = MAX_LFS_FILESIZE;
385 sb->s_blocksize = PAGE_CACHE_SIZE;
386 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
387 sb->s_magic = PSTOREFS_MAGIC;
388 sb->s_op = &pstore_ops;
389 sb->s_time_gran = 1;
390
391 parse_options(data);
392
393 inode = pstore_get_inode(sb);
394 if (inode) {
395 inode->i_mode = S_IFDIR | 0755;
396 inode->i_op = &pstore_dir_inode_operations;
397 inode->i_fop = &simple_dir_operations;
398 inc_nlink(inode);
399 }
400 sb->s_root = d_make_root(inode);
401 if (!sb->s_root)
402 return -ENOMEM;
403
404 pstore_get_records(0);
405
406 return 0;
407 }
408
pstore_mount(struct file_system_type * fs_type,int flags,const char * dev_name,void * data)409 static struct dentry *pstore_mount(struct file_system_type *fs_type,
410 int flags, const char *dev_name, void *data)
411 {
412 return mount_single(fs_type, flags, data, pstore_fill_super);
413 }
414
pstore_kill_sb(struct super_block * sb)415 static void pstore_kill_sb(struct super_block *sb)
416 {
417 kill_litter_super(sb);
418 pstore_sb = NULL;
419 }
420
421 static struct file_system_type pstore_fs_type = {
422 .name = "pstore",
423 .mount = pstore_mount,
424 .kill_sb = pstore_kill_sb,
425 };
426
427 static struct kobject *pstore_kobj;
428
init_pstore_fs(void)429 static int __init init_pstore_fs(void)
430 {
431 int err = 0;
432
433 /* Create a convenient mount point for people to access pstore */
434 pstore_kobj = kobject_create_and_add("pstore", fs_kobj);
435 if (!pstore_kobj) {
436 err = -ENOMEM;
437 goto out;
438 }
439
440 err = register_filesystem(&pstore_fs_type);
441 if (err < 0)
442 kobject_put(pstore_kobj);
443
444 out:
445 return err;
446 }
447 module_init(init_pstore_fs)
448
449 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
450 MODULE_LICENSE("GPL");
451