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
31 static DEFINE_MUTEX(records_list_lock);
32 static LIST_HEAD(records_list);
33
34 static DEFINE_MUTEX(pstore_sb_lock);
35 static struct super_block *pstore_sb;
36
37 struct pstore_private {
38 struct list_head list;
39 struct dentry *dentry;
40 struct pstore_record *record;
41 size_t total_size;
42 };
43
44 struct 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
free_pstore_private(struct pstore_private * private)52 static 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->priv);
59 kfree(private->record);
60 }
61 kfree(private);
62 }
63
pstore_ftrace_seq_start(struct seq_file * s,loff_t * pos)64 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
65 {
66 struct pstore_private *ps = s->private;
67 struct pstore_ftrace_seq_data *data;
68
69 data = kzalloc(sizeof(*data), GFP_KERNEL);
70 if (!data)
71 return NULL;
72
73 data->off = ps->total_size % REC_SIZE;
74 data->off += *pos * REC_SIZE;
75 if (data->off + REC_SIZE > ps->total_size) {
76 kfree(data);
77 return NULL;
78 }
79
80 return data;
81
82 }
83
pstore_ftrace_seq_stop(struct seq_file * s,void * v)84 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)
85 {
86 kfree(v);
87 }
88
pstore_ftrace_seq_next(struct seq_file * s,void * v,loff_t * pos)89 static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos)
90 {
91 struct pstore_private *ps = s->private;
92 struct pstore_ftrace_seq_data *data = v;
93
94 (*pos)++;
95 data->off += REC_SIZE;
96 if (data->off + REC_SIZE > ps->total_size)
97 return NULL;
98
99 return data;
100 }
101
pstore_ftrace_seq_show(struct seq_file * s,void * v)102 static int pstore_ftrace_seq_show(struct seq_file *s, void *v)
103 {
104 struct pstore_private *ps = s->private;
105 struct pstore_ftrace_seq_data *data = v;
106 struct pstore_ftrace_record *rec;
107
108 if (!data)
109 return 0;
110
111 rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
112
113 seq_printf(s, "CPU:%d ts:%llu %08lx %08lx %ps <- %pS\n",
114 pstore_ftrace_decode_cpu(rec),
115 pstore_ftrace_read_timestamp(rec),
116 rec->ip, rec->parent_ip, (void *)rec->ip,
117 (void *)rec->parent_ip);
118
119 return 0;
120 }
121
122 static const struct seq_operations pstore_ftrace_seq_ops = {
123 .start = pstore_ftrace_seq_start,
124 .next = pstore_ftrace_seq_next,
125 .stop = pstore_ftrace_seq_stop,
126 .show = pstore_ftrace_seq_show,
127 };
128
pstore_file_read(struct file * file,char __user * userbuf,size_t count,loff_t * ppos)129 static ssize_t pstore_file_read(struct file *file, char __user *userbuf,
130 size_t count, loff_t *ppos)
131 {
132 struct seq_file *sf = file->private_data;
133 struct pstore_private *ps = sf->private;
134
135 if (ps->record->type == PSTORE_TYPE_FTRACE)
136 return seq_read(file, userbuf, count, ppos);
137 return simple_read_from_buffer(userbuf, count, ppos,
138 ps->record->buf, ps->total_size);
139 }
140
pstore_file_open(struct inode * inode,struct file * file)141 static int pstore_file_open(struct inode *inode, struct file *file)
142 {
143 struct pstore_private *ps = inode->i_private;
144 struct seq_file *sf;
145 int err;
146 const struct seq_operations *sops = NULL;
147
148 if (ps->record->type == PSTORE_TYPE_FTRACE)
149 sops = &pstore_ftrace_seq_ops;
150
151 err = seq_open(file, sops);
152 if (err < 0)
153 return err;
154
155 sf = file->private_data;
156 sf->private = ps;
157
158 return 0;
159 }
160
pstore_file_llseek(struct file * file,loff_t off,int whence)161 static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence)
162 {
163 struct seq_file *sf = file->private_data;
164
165 if (sf->op)
166 return seq_lseek(file, off, whence);
167 return default_llseek(file, off, whence);
168 }
169
170 static const struct file_operations pstore_file_operations = {
171 .open = pstore_file_open,
172 .read = pstore_file_read,
173 .llseek = pstore_file_llseek,
174 .release = seq_release,
175 };
176
177 /*
178 * When a file is unlinked from our file system we call the
179 * platform driver to erase the record from persistent store.
180 */
pstore_unlink(struct inode * dir,struct dentry * dentry)181 static int pstore_unlink(struct inode *dir, struct dentry *dentry)
182 {
183 struct pstore_private *p = d_inode(dentry)->i_private;
184 struct pstore_record *record = p->record;
185 int rc = 0;
186
187 if (!record->psi->erase)
188 return -EPERM;
189
190 /* Make sure we can't race while removing this file. */
191 mutex_lock(&records_list_lock);
192 if (!list_empty(&p->list))
193 list_del_init(&p->list);
194 else
195 rc = -ENOENT;
196 p->dentry = NULL;
197 mutex_unlock(&records_list_lock);
198 if (rc)
199 return rc;
200
201 mutex_lock(&record->psi->read_mutex);
202 record->psi->erase(record);
203 mutex_unlock(&record->psi->read_mutex);
204
205 return simple_unlink(dir, dentry);
206 }
207
pstore_evict_inode(struct inode * inode)208 static void pstore_evict_inode(struct inode *inode)
209 {
210 struct pstore_private *p = inode->i_private;
211
212 clear_inode(inode);
213 free_pstore_private(p);
214 }
215
216 static const struct inode_operations pstore_dir_inode_operations = {
217 .lookup = simple_lookup,
218 .unlink = pstore_unlink,
219 };
220
pstore_get_inode(struct super_block * sb)221 static struct inode *pstore_get_inode(struct super_block *sb)
222 {
223 struct inode *inode = new_inode(sb);
224 if (inode) {
225 inode->i_ino = get_next_ino();
226 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
227 }
228 return inode;
229 }
230
231 enum {
232 Opt_kmsg_bytes, Opt_err
233 };
234
235 static const match_table_t tokens = {
236 {Opt_kmsg_bytes, "kmsg_bytes=%u"},
237 {Opt_err, NULL}
238 };
239
parse_options(char * options)240 static void parse_options(char *options)
241 {
242 char *p;
243 substring_t args[MAX_OPT_ARGS];
244 int option;
245
246 if (!options)
247 return;
248
249 while ((p = strsep(&options, ",")) != NULL) {
250 int token;
251
252 if (!*p)
253 continue;
254
255 token = match_token(p, tokens, args);
256 switch (token) {
257 case Opt_kmsg_bytes:
258 if (!match_int(&args[0], &option))
259 pstore_set_kmsg_bytes(option);
260 break;
261 }
262 }
263 }
264
265 /*
266 * Display the mount options in /proc/mounts.
267 */
pstore_show_options(struct seq_file * m,struct dentry * root)268 static int pstore_show_options(struct seq_file *m, struct dentry *root)
269 {
270 if (kmsg_bytes != CONFIG_PSTORE_DEFAULT_KMSG_BYTES)
271 seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes);
272 return 0;
273 }
274
pstore_remount(struct super_block * sb,int * flags,char * data)275 static int pstore_remount(struct super_block *sb, int *flags, char *data)
276 {
277 sync_filesystem(sb);
278 parse_options(data);
279
280 return 0;
281 }
282
283 static const struct super_operations pstore_ops = {
284 .statfs = simple_statfs,
285 .drop_inode = generic_delete_inode,
286 .evict_inode = pstore_evict_inode,
287 .remount_fs = pstore_remount,
288 .show_options = pstore_show_options,
289 };
290
psinfo_lock_root(void)291 static struct dentry *psinfo_lock_root(void)
292 {
293 struct dentry *root;
294
295 mutex_lock(&pstore_sb_lock);
296 /*
297 * Having no backend is fine -- no records appear.
298 * Not being mounted is fine -- nothing to do.
299 */
300 if (!psinfo || !pstore_sb) {
301 mutex_unlock(&pstore_sb_lock);
302 return NULL;
303 }
304
305 root = pstore_sb->s_root;
306 inode_lock(d_inode(root));
307 mutex_unlock(&pstore_sb_lock);
308
309 return root;
310 }
311
pstore_put_backend_records(struct pstore_info * psi)312 int pstore_put_backend_records(struct pstore_info *psi)
313 {
314 struct pstore_private *pos, *tmp;
315 struct dentry *root;
316 int rc = 0;
317
318 root = psinfo_lock_root();
319 if (!root)
320 return 0;
321
322 mutex_lock(&records_list_lock);
323 list_for_each_entry_safe(pos, tmp, &records_list, list) {
324 if (pos->record->psi == psi) {
325 list_del_init(&pos->list);
326 rc = simple_unlink(d_inode(root), pos->dentry);
327 if (WARN_ON(rc))
328 break;
329 d_drop(pos->dentry);
330 dput(pos->dentry);
331 pos->dentry = NULL;
332 }
333 }
334 mutex_unlock(&records_list_lock);
335
336 inode_unlock(d_inode(root));
337
338 return rc;
339 }
340
341 /*
342 * Make a regular file in the root directory of our file system.
343 * Load it up with "size" bytes of data from "buf".
344 * Set the mtime & ctime to the date that this record was originally stored.
345 */
pstore_mkfile(struct dentry * root,struct pstore_record * record)346 int pstore_mkfile(struct dentry *root, struct pstore_record *record)
347 {
348 struct dentry *dentry;
349 struct inode *inode;
350 int rc = 0;
351 char name[PSTORE_NAMELEN];
352 struct pstore_private *private, *pos;
353 size_t size = record->size + record->ecc_notice_size;
354
355 if (WARN_ON(!inode_is_locked(d_inode(root))))
356 return -EINVAL;
357
358 rc = -EEXIST;
359 /* Skip records that are already present in the filesystem. */
360 mutex_lock(&records_list_lock);
361 list_for_each_entry(pos, &records_list, list) {
362 if (pos->record->type == record->type &&
363 pos->record->id == record->id &&
364 pos->record->psi == record->psi)
365 goto fail;
366 }
367
368 rc = -ENOMEM;
369 inode = pstore_get_inode(root->d_sb);
370 if (!inode)
371 goto fail;
372 inode->i_mode = S_IFREG | 0444;
373 inode->i_fop = &pstore_file_operations;
374 scnprintf(name, sizeof(name), "%s-%s-%llu%s",
375 pstore_type_to_name(record->type),
376 record->psi->name, record->id,
377 record->compressed ? ".enc.z" : "");
378
379 private = kzalloc(sizeof(*private), GFP_KERNEL);
380 if (!private)
381 goto fail_inode;
382
383 dentry = d_alloc_name(root, name);
384 if (!dentry)
385 goto fail_private;
386
387 private->dentry = dentry;
388 private->record = record;
389 inode->i_size = private->total_size = size;
390 inode->i_private = private;
391
392 if (record->time.tv_sec)
393 inode->i_mtime = inode->i_ctime = record->time;
394
395 d_add(dentry, inode);
396
397 list_add(&private->list, &records_list);
398 mutex_unlock(&records_list_lock);
399
400 return 0;
401
402 fail_private:
403 free_pstore_private(private);
404 fail_inode:
405 iput(inode);
406 fail:
407 mutex_unlock(&records_list_lock);
408 return rc;
409 }
410
411 /*
412 * Read all the records from the persistent store. Create
413 * files in our filesystem. Don't warn about -EEXIST errors
414 * when we are re-scanning the backing store looking to add new
415 * error records.
416 */
pstore_get_records(int quiet)417 void pstore_get_records(int quiet)
418 {
419 struct dentry *root;
420
421 root = psinfo_lock_root();
422 if (!root)
423 return;
424
425 pstore_get_backend_records(psinfo, root, quiet);
426 inode_unlock(d_inode(root));
427 }
428
pstore_fill_super(struct super_block * sb,void * data,int silent)429 static int pstore_fill_super(struct super_block *sb, void *data, int silent)
430 {
431 struct inode *inode;
432
433 sb->s_maxbytes = MAX_LFS_FILESIZE;
434 sb->s_blocksize = PAGE_SIZE;
435 sb->s_blocksize_bits = PAGE_SHIFT;
436 sb->s_magic = PSTOREFS_MAGIC;
437 sb->s_op = &pstore_ops;
438 sb->s_time_gran = 1;
439
440 parse_options(data);
441
442 inode = pstore_get_inode(sb);
443 if (inode) {
444 inode->i_mode = S_IFDIR | 0750;
445 inode->i_op = &pstore_dir_inode_operations;
446 inode->i_fop = &simple_dir_operations;
447 inc_nlink(inode);
448 }
449 sb->s_root = d_make_root(inode);
450 if (!sb->s_root)
451 return -ENOMEM;
452
453 mutex_lock(&pstore_sb_lock);
454 pstore_sb = sb;
455 mutex_unlock(&pstore_sb_lock);
456
457 pstore_get_records(0);
458
459 return 0;
460 }
461
pstore_mount(struct file_system_type * fs_type,int flags,const char * dev_name,void * data)462 static struct dentry *pstore_mount(struct file_system_type *fs_type,
463 int flags, const char *dev_name, void *data)
464 {
465 return mount_single(fs_type, flags, data, pstore_fill_super);
466 }
467
pstore_kill_sb(struct super_block * sb)468 static void pstore_kill_sb(struct super_block *sb)
469 {
470 mutex_lock(&pstore_sb_lock);
471 WARN_ON(pstore_sb && pstore_sb != sb);
472
473 kill_litter_super(sb);
474 pstore_sb = NULL;
475
476 mutex_lock(&records_list_lock);
477 INIT_LIST_HEAD(&records_list);
478 mutex_unlock(&records_list_lock);
479
480 mutex_unlock(&pstore_sb_lock);
481 }
482
483 static struct file_system_type pstore_fs_type = {
484 .owner = THIS_MODULE,
485 .name = "pstore",
486 .mount = pstore_mount,
487 .kill_sb = pstore_kill_sb,
488 };
489
pstore_init_fs(void)490 int __init pstore_init_fs(void)
491 {
492 int err;
493
494 /* Create a convenient mount point for people to access pstore */
495 err = sysfs_create_mount_point(fs_kobj, "pstore");
496 if (err)
497 goto out;
498
499 err = register_filesystem(&pstore_fs_type);
500 if (err < 0)
501 sysfs_remove_mount_point(fs_kobj, "pstore");
502
503 out:
504 return err;
505 }
506
pstore_exit_fs(void)507 void __exit pstore_exit_fs(void)
508 {
509 unregister_filesystem(&pstore_fs_type);
510 sysfs_remove_mount_point(fs_kobj, "pstore");
511 }
512