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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/string.h>
28#include <linux/mount.h>
29#include <linux/ramfs.h>
30#include <linux/parser.h>
31#include <linux/sched.h>
32#include <linux/magic.h>
33#include <linux/pstore.h>
34#include <linux/slab.h>
35#include <linux/uaccess.h>
36
37#include "internal.h"
38
39#define PSTORE_NAMELEN 64
40
41struct pstore_private {
42 struct pstore_info *psi;
43 enum pstore_type_id type;
44 u64 id;
45 ssize_t size;
46 char data[];
47};
48
49static int pstore_file_open(struct inode *inode, struct file *file)
50{
51 file->private_data = inode->i_private;
52 return 0;
53}
54
55static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
56 size_t count, loff_t *ppos)
57{
58 struct pstore_private *ps = file->private_data;
59
60 return simple_read_from_buffer(userbuf, count, ppos, ps->data, ps->size);
61}
62
63static const struct file_operations pstore_file_operations = {
64 .open = pstore_file_open,
65 .read = pstore_file_read,
66 .llseek = default_llseek,
67};
68
69/*
70 * When a file is unlinked from our file system we call the
71 * platform driver to erase the record from persistent store.
72 */
73static int pstore_unlink(struct inode *dir, struct dentry *dentry)
74{
75 struct pstore_private *p = dentry->d_inode->i_private;
76
77 p->psi->erase(p->type, p->id, p->psi);
78
79 return simple_unlink(dir, dentry);
80}
81
82static void pstore_evict_inode(struct inode *inode)
83{
84 end_writeback(inode);
85 kfree(inode->i_private);
86}
87
88static const struct inode_operations pstore_dir_inode_operations = {
89 .lookup = simple_lookup,
90 .unlink = pstore_unlink,
91};
92
93static struct inode *pstore_get_inode(struct super_block *sb,
94 const struct inode *dir, int mode, dev_t dev)
95{
96 struct inode *inode = new_inode(sb);
97
98 if (inode) {
99 inode->i_ino = get_next_ino();
100 inode->i_uid = inode->i_gid = 0;
101 inode->i_mode = mode;
102 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
103 switch (mode & S_IFMT) {
104 case S_IFREG:
105 inode->i_fop = &pstore_file_operations;
106 break;
107 case S_IFDIR:
108 inode->i_op = &pstore_dir_inode_operations;
109 inode->i_fop = &simple_dir_operations;
110 inc_nlink(inode);
111 break;
112 }
113 }
114 return inode;
115}
116
117enum {
118 Opt_kmsg_bytes, Opt_err
119};
120
121static const match_table_t tokens = {
122 {Opt_kmsg_bytes, "kmsg_bytes=%u"},
123 {Opt_err, NULL}
124};
125
126static void parse_options(char *options)
127{
128 char *p;
129 substring_t args[MAX_OPT_ARGS];
130 int option;
131
132 if (!options)
133 return;
134
135 while ((p = strsep(&options, ",")) != NULL) {
136 int token;
137
138 if (!*p)
139 continue;
140
141 token = match_token(p, tokens, args);
142 switch (token) {
143 case Opt_kmsg_bytes:
144 if (!match_int(&args[0], &option))
145 pstore_set_kmsg_bytes(option);
146 break;
147 }
148 }
149}
150
151static int pstore_remount(struct super_block *sb, int *flags, char *data)
152{
153 parse_options(data);
154
155 return 0;
156}
157
158static const struct super_operations pstore_ops = {
159 .statfs = simple_statfs,
160 .drop_inode = generic_delete_inode,
161 .evict_inode = pstore_evict_inode,
162 .remount_fs = pstore_remount,
163 .show_options = generic_show_options,
164};
165
166static struct super_block *pstore_sb;
167
168int pstore_is_mounted(void)
169{
170 return pstore_sb != NULL;
171}
172
173/*
174 * Make a regular file in the root directory of our file system.
175 * Load it up with "size" bytes of data from "buf".
176 * Set the mtime & ctime to the date that this record was originally stored.
177 */
178int pstore_mkfile(enum pstore_type_id type, char *psname, u64 id,
179 char *data, size_t size, struct timespec time,
180 struct pstore_info *psi)
181{
182 struct dentry *root = pstore_sb->s_root;
183 struct dentry *dentry;
184 struct inode *inode;
185 int rc;
186 char name[PSTORE_NAMELEN];
187 struct pstore_private *private;
188
189 rc = -ENOMEM;
190 inode = pstore_get_inode(pstore_sb, root->d_inode, S_IFREG | 0444, 0);
191 if (!inode)
192 goto fail;
193 private = kmalloc(sizeof *private + size, GFP_KERNEL);
194 if (!private)
195 goto fail_alloc;
196 private->type = type;
197 private->id = id;
198 private->psi = psi;
199
200 switch (type) {
201 case PSTORE_TYPE_DMESG:
202 sprintf(name, "dmesg-%s-%lld", psname, id);
203 break;
204 case PSTORE_TYPE_MCE:
205 sprintf(name, "mce-%s-%lld", psname, id);
206 break;
207 case PSTORE_TYPE_UNKNOWN:
208 sprintf(name, "unknown-%s-%lld", psname, id);
209 break;
210 default:
211 sprintf(name, "type%d-%s-%lld", type, psname, id);
212 break;
213 }
214
215 mutex_lock(&root->d_inode->i_mutex);
216
217 rc = -ENOSPC;
218 dentry = d_alloc_name(root, name);
219 if (IS_ERR(dentry))
220 goto fail_lockedalloc;
221
222 memcpy(private->data, data, size);
223 inode->i_size = private->size = size;
224
225 inode->i_private = private;
226
227 if (time.tv_sec)
228 inode->i_mtime = inode->i_ctime = time;
229
230 d_add(dentry, inode);
231
232 mutex_unlock(&root->d_inode->i_mutex);
233
234 return 0;
235
236fail_lockedalloc:
237 mutex_unlock(&root->d_inode->i_mutex);
238 kfree(private);
239fail_alloc:
240 iput(inode);
241
242fail:
243 return rc;
244}
245
246int pstore_fill_super(struct super_block *sb, void *data, int silent)
247{
248 struct inode *inode = NULL;
249 struct dentry *root;
250 int err;
251
252 save_mount_options(sb, data);
253
254 pstore_sb = sb;
255
256 sb->s_maxbytes = MAX_LFS_FILESIZE;
257 sb->s_blocksize = PAGE_CACHE_SIZE;
258 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
259 sb->s_magic = PSTOREFS_MAGIC;
260 sb->s_op = &pstore_ops;
261 sb->s_time_gran = 1;
262
263 parse_options(data);
264
265 inode = pstore_get_inode(sb, NULL, S_IFDIR | 0755, 0);
266 if (!inode) {
267 err = -ENOMEM;
268 goto fail;
269 }
270 /* override ramfs "dir" options so we catch unlink(2) */
271 inode->i_op = &pstore_dir_inode_operations;
272
273 root = d_alloc_root(inode);
274 sb->s_root = root;
275 if (!root) {
276 err = -ENOMEM;
277 goto fail;
278 }
279
280 pstore_get_records();
281
282 return 0;
283fail:
284 iput(inode);
285 return err;
286}
287
288static struct dentry *pstore_mount(struct file_system_type *fs_type,
289 int flags, const char *dev_name, void *data)
290{
291 return mount_single(fs_type, flags, data, pstore_fill_super);
292}
293
294static void pstore_kill_sb(struct super_block *sb)
295{
296 kill_litter_super(sb);
297 pstore_sb = NULL;
298}
299
300static struct file_system_type pstore_fs_type = {
301 .name = "pstore",
302 .mount = pstore_mount,
303 .kill_sb = pstore_kill_sb,
304};
305
306static int __init init_pstore_fs(void)
307{
308 return register_filesystem(&pstore_fs_type);
309}
310module_init(init_pstore_fs)
311
312MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
313MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Persistent Storage - ramfs parts.
4 *
5 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
6 */
7
8#include <linux/module.h>
9#include <linux/fs.h>
10#include <linux/fsnotify.h>
11#include <linux/pagemap.h>
12#include <linux/highmem.h>
13#include <linux/time.h>
14#include <linux/init.h>
15#include <linux/list.h>
16#include <linux/string.h>
17#include <linux/mount.h>
18#include <linux/seq_file.h>
19#include <linux/ramfs.h>
20#include <linux/parser.h>
21#include <linux/sched.h>
22#include <linux/magic.h>
23#include <linux/pstore.h>
24#include <linux/slab.h>
25#include <linux/uaccess.h>
26
27#include "internal.h"
28
29#define PSTORE_NAMELEN 64
30
31static DEFINE_MUTEX(records_list_lock);
32static LIST_HEAD(records_list);
33
34static DEFINE_MUTEX(pstore_sb_lock);
35static struct super_block *pstore_sb;
36
37struct pstore_private {
38 struct list_head list;
39 struct dentry *dentry;
40 struct pstore_record *record;
41 size_t total_size;
42};
43
44struct pstore_ftrace_seq_data {
45 const void *ptr;
46 size_t off;
47 size_t size;
48};
49
50#define REC_SIZE sizeof(struct pstore_ftrace_record)
51
52static void free_pstore_private(struct pstore_private *private)
53{
54 if (!private)
55 return;
56 if (private->record) {
57 kfree(private->record->buf);
58 kfree(private->record);
59 }
60 kfree(private);
61}
62
63static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
64{
65 struct pstore_private *ps = s->private;
66 struct pstore_ftrace_seq_data *data;
67
68 data = kzalloc(sizeof(*data), GFP_KERNEL);
69 if (!data)
70 return NULL;
71
72 data->off = ps->total_size % REC_SIZE;
73 data->off += *pos * REC_SIZE;
74 if (data->off + REC_SIZE > ps->total_size) {
75 kfree(data);
76 return NULL;
77 }
78
79 return data;
80
81}
82
83static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
84{
85 kfree(v);
86}
87
88static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
89{
90 struct pstore_private *ps = s->private;
91 struct pstore_ftrace_seq_data *data = v;
92
93 (*pos)++;
94 data->off += REC_SIZE;
95 if (data->off + REC_SIZE > ps->total_size)
96 return NULL;
97
98 return data;
99}
100
101static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
102{
103 struct pstore_private *ps = s->private;
104 struct pstore_ftrace_seq_data *data = v;
105 struct pstore_ftrace_record *rec;
106
107 if (!data)
108 return 0;
109
110 rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
111
112 seq_printf(s, "CPU:%d ts:%llu %08lx %08lx %ps <- %pS\n",
113 pstore_ftrace_decode_cpu(rec),
114 pstore_ftrace_read_timestamp(rec),
115 rec->ip, rec->parent_ip, (void *)rec->ip,
116 (void *)rec->parent_ip);
117
118 return 0;
119}
120
121static const struct seq_operations pstore_ftrace_seq_ops = {
122 .start = pstore_ftrace_seq_start,
123 .next = pstore_ftrace_seq_next,
124 .stop = pstore_ftrace_seq_stop,
125 .show = pstore_ftrace_seq_show,
126};
127
128static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
129 size_t count, loff_t *ppos)
130{
131 struct seq_file *sf = file->private_data;
132 struct pstore_private *ps = sf->private;
133
134 if (ps->record->type == PSTORE_TYPE_FTRACE)
135 return seq_read(file, userbuf, count, ppos);
136 return simple_read_from_buffer(userbuf, count, ppos,
137 ps->record->buf, ps->total_size);
138}
139
140static int pstore_file_open(struct inode *inode, struct file *file)
141{
142 struct pstore_private *ps = inode->i_private;
143 struct seq_file *sf;
144 int err;
145 const struct seq_operations *sops = NULL;
146
147 if (ps->record->type == PSTORE_TYPE_FTRACE)
148 sops = &pstore_ftrace_seq_ops;
149
150 err = seq_open(file, sops);
151 if (err < 0)
152 return err;
153
154 sf = file->private_data;
155 sf->private = ps;
156
157 return 0;
158}
159
160static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
161{
162 struct seq_file *sf = file->private_data;
163
164 if (sf->op)
165 return seq_lseek(file, off, whence);
166 return default_llseek(file, off, whence);
167}
168
169static const struct file_operations pstore_file_operations = {
170 .open = pstore_file_open,
171 .read = pstore_file_read,
172 .llseek = pstore_file_llseek,
173 .release = seq_release,
174};
175
176/*
177 * When a file is unlinked from our file system we call the
178 * platform driver to erase the record from persistent store.
179 */
180static int pstore_unlink(struct inode *dir, struct dentry *dentry)
181{
182 struct pstore_private *p = d_inode(dentry)->i_private;
183 struct pstore_record *record = p->record;
184 int rc = 0;
185
186 if (!record->psi->erase)
187 return -EPERM;
188
189 /* Make sure we can't race while removing this file. */
190 mutex_lock(&records_list_lock);
191 if (!list_empty(&p->list))
192 list_del_init(&p->list);
193 else
194 rc = -ENOENT;
195 p->dentry = NULL;
196 mutex_unlock(&records_list_lock);
197 if (rc)
198 return rc;
199
200 mutex_lock(&record->psi->read_mutex);
201 record->psi->erase(record);
202 mutex_unlock(&record->psi->read_mutex);
203
204 return simple_unlink(dir, dentry);
205}
206
207static void pstore_evict_inode(struct inode *inode)
208{
209 struct pstore_private *p = inode->i_private;
210
211 clear_inode(inode);
212 free_pstore_private(p);
213}
214
215static const struct inode_operations pstore_dir_inode_operations = {
216 .lookup = simple_lookup,
217 .unlink = pstore_unlink,
218};
219
220static struct inode *pstore_get_inode(struct super_block *sb)
221{
222 struct inode *inode = new_inode(sb);
223 if (inode) {
224 inode->i_ino = get_next_ino();
225 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
226 }
227 return inode;
228}
229
230enum {
231 Opt_kmsg_bytes, Opt_err
232};
233
234static const match_table_t tokens = {
235 {Opt_kmsg_bytes, "kmsg_bytes=%u"},
236 {Opt_err, NULL}
237};
238
239static void parse_options(char *options)
240{
241 char *p;
242 substring_t args[MAX_OPT_ARGS];
243 int option;
244
245 if (!options)
246 return;
247
248 while ((p = strsep(&options, ",")) != NULL) {
249 int token;
250
251 if (!*p)
252 continue;
253
254 token = match_token(p, tokens, args);
255 switch (token) {
256 case Opt_kmsg_bytes:
257 if (!match_int(&args[0], &option))
258 pstore_set_kmsg_bytes(option);
259 break;
260 }
261 }
262}
263
264/*
265 * Display the mount options in /proc/mounts.
266 */
267static int pstore_show_options(struct seq_file *m, struct dentry *root)
268{
269 if (kmsg_bytes != PSTORE_DEFAULT_KMSG_BYTES)
270 seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
271 return 0;
272}
273
274static int pstore_remount(struct super_block *sb, int *flags, char *data)
275{
276 sync_filesystem(sb);
277 parse_options(data);
278
279 return 0;
280}
281
282static const struct super_operations pstore_ops = {
283 .statfs = simple_statfs,
284 .drop_inode = generic_delete_inode,
285 .evict_inode = pstore_evict_inode,
286 .remount_fs = pstore_remount,
287 .show_options = pstore_show_options,
288};
289
290static struct dentry *psinfo_lock_root(void)
291{
292 struct dentry *root;
293
294 mutex_lock(&pstore_sb_lock);
295 /*
296 * Having no backend is fine -- no records appear.
297 * Not being mounted is fine -- nothing to do.
298 */
299 if (!psinfo || !pstore_sb) {
300 mutex_unlock(&pstore_sb_lock);
301 return NULL;
302 }
303
304 root = pstore_sb->s_root;
305 inode_lock(d_inode(root));
306 mutex_unlock(&pstore_sb_lock);
307
308 return root;
309}
310
311int pstore_put_backend_records(struct pstore_info *psi)
312{
313 struct pstore_private *pos, *tmp;
314 struct dentry *root;
315 int rc = 0;
316
317 root = psinfo_lock_root();
318 if (!root)
319 return 0;
320
321 mutex_lock(&records_list_lock);
322 list_for_each_entry_safe(pos, tmp, &records_list, list) {
323 if (pos->record->psi == psi) {
324 list_del_init(&pos->list);
325 rc = simple_unlink(d_inode(root), pos->dentry);
326 if (WARN_ON(rc))
327 break;
328 d_drop(pos->dentry);
329 dput(pos->dentry);
330 pos->dentry = NULL;
331 }
332 }
333 mutex_unlock(&records_list_lock);
334
335 inode_unlock(d_inode(root));
336
337 return rc;
338}
339
340/*
341 * Make a regular file in the root directory of our file system.
342 * Load it up with "size" bytes of data from "buf".
343 * Set the mtime & ctime to the date that this record was originally stored.
344 */
345int pstore_mkfile(struct dentry *root, struct pstore_record *record)
346{
347 struct dentry *dentry;
348 struct inode *inode;
349 int rc = 0;
350 char name[PSTORE_NAMELEN];
351 struct pstore_private *private, *pos;
352 size_t size = record->size + record->ecc_notice_size;
353
354 if (WARN_ON(!inode_is_locked(d_inode(root))))
355 return -EINVAL;
356
357 rc = -EEXIST;
358 /* Skip records that are already present in the filesystem. */
359 mutex_lock(&records_list_lock);
360 list_for_each_entry(pos, &records_list, list) {
361 if (pos->record->type == record->type &&
362 pos->record->id == record->id &&
363 pos->record->psi == record->psi)
364 goto fail;
365 }
366
367 rc = -ENOMEM;
368 inode = pstore_get_inode(root->d_sb);
369 if (!inode)
370 goto fail;
371 inode->i_mode = S_IFREG | 0444;
372 inode->i_fop = &pstore_file_operations;
373 scnprintf(name, sizeof(name), "%s-%s-%llu%s",
374 pstore_type_to_name(record->type),
375 record->psi->name, record->id,
376 record->compressed ? ".enc.z" : "");
377
378 private = kzalloc(sizeof(*private), GFP_KERNEL);
379 if (!private)
380 goto fail_inode;
381
382 dentry = d_alloc_name(root, name);
383 if (!dentry)
384 goto fail_private;
385
386 private->dentry = dentry;
387 private->record = record;
388 inode->i_size = private->total_size = size;
389 inode->i_private = private;
390
391 if (record->time.tv_sec)
392 inode->i_mtime = inode->i_ctime = record->time;
393
394 d_add(dentry, inode);
395
396 list_add(&private->list, &records_list);
397 mutex_unlock(&records_list_lock);
398
399 return 0;
400
401fail_private:
402 free_pstore_private(private);
403fail_inode:
404 iput(inode);
405fail:
406 mutex_unlock(&records_list_lock);
407 return rc;
408}
409
410/*
411 * Read all the records from the persistent store. Create
412 * files in our filesystem. Don't warn about -EEXIST errors
413 * when we are re-scanning the backing store looking to add new
414 * error records.
415 */
416void pstore_get_records(int quiet)
417{
418 struct dentry *root;
419
420 root = psinfo_lock_root();
421 if (!root)
422 return;
423
424 pstore_get_backend_records(psinfo, root, quiet);
425 inode_unlock(d_inode(root));
426}
427
428static int pstore_fill_super(struct super_block *sb, void *data, int silent)
429{
430 struct inode *inode;
431
432 sb->s_maxbytes = MAX_LFS_FILESIZE;
433 sb->s_blocksize = PAGE_SIZE;
434 sb->s_blocksize_bits = PAGE_SHIFT;
435 sb->s_magic = PSTOREFS_MAGIC;
436 sb->s_op = &pstore_ops;
437 sb->s_time_gran = 1;
438
439 parse_options(data);
440
441 inode = pstore_get_inode(sb);
442 if (inode) {
443 inode->i_mode = S_IFDIR | 0750;
444 inode->i_op = &pstore_dir_inode_operations;
445 inode->i_fop = &simple_dir_operations;
446 inc_nlink(inode);
447 }
448 sb->s_root = d_make_root(inode);
449 if (!sb->s_root)
450 return -ENOMEM;
451
452 mutex_lock(&pstore_sb_lock);
453 pstore_sb = sb;
454 mutex_unlock(&pstore_sb_lock);
455
456 pstore_get_records(0);
457
458 return 0;
459}
460
461static struct dentry *pstore_mount(struct file_system_type *fs_type,
462 int flags, const char *dev_name, void *data)
463{
464 return mount_single(fs_type, flags, data, pstore_fill_super);
465}
466
467static void pstore_kill_sb(struct super_block *sb)
468{
469 mutex_lock(&pstore_sb_lock);
470 WARN_ON(pstore_sb != sb);
471
472 kill_litter_super(sb);
473 pstore_sb = NULL;
474
475 mutex_lock(&records_list_lock);
476 INIT_LIST_HEAD(&records_list);
477 mutex_unlock(&records_list_lock);
478
479 mutex_unlock(&pstore_sb_lock);
480}
481
482static struct file_system_type pstore_fs_type = {
483 .owner = THIS_MODULE,
484 .name = "pstore",
485 .mount = pstore_mount,
486 .kill_sb = pstore_kill_sb,
487};
488
489int __init pstore_init_fs(void)
490{
491 int err;
492
493 /* Create a convenient mount point for people to access pstore */
494 err = sysfs_create_mount_point(fs_kobj, "pstore");
495 if (err)
496 goto out;
497
498 err = register_filesystem(&pstore_fs_type);
499 if (err < 0)
500 sysfs_remove_mount_point(fs_kobj, "pstore");
501
502out:
503 return err;
504}
505
506void __exit pstore_exit_fs(void)
507{
508 unregister_filesystem(&pstore_fs_type);
509 sysfs_remove_mount_point(fs_kobj, "pstore");
510}