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 | |
52 | static void free_pstore_private(struct pstore_private *private) |
53 | { |
54 | if (!private) |
55 | return; |
56 | if (private->record) { |
57 | kvfree(addr: private->record->buf); |
58 | kfree(objp: private->record->priv); |
59 | kfree(objp: private->record); |
60 | } |
61 | kfree(objp: private); |
62 | } |
63 | |
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(size: 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(objp: data); |
77 | return NULL; |
78 | } |
79 | |
80 | return data; |
81 | |
82 | } |
83 | |
84 | static void pstore_ftrace_seq_stop(struct seq_file *s, void *v) |
85 | { |
86 | kfree(objp: v); |
87 | } |
88 | |
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 | |
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(m: s, fmt: "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 | |
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(to: userbuf, count, ppos, |
138 | from: ps->record->buf, available: ps->total_size); |
139 | } |
140 | |
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 | |
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, offset: 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 | */ |
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(head: &p->list)) |
193 | list_del_init(entry: &p->list); |
194 | else |
195 | rc = -ENOENT; |
196 | p->dentry = NULL; |
197 | mutex_unlock(lock: &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(lock: &record->psi->read_mutex); |
204 | |
205 | return simple_unlink(dir, dentry); |
206 | } |
207 | |
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(private: p); |
214 | } |
215 | |
216 | static const struct inode_operations pstore_dir_inode_operations = { |
217 | .lookup = simple_lookup, |
218 | .unlink = pstore_unlink, |
219 | }; |
220 | |
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 | simple_inode_init_ts(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 | |
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, table: tokens, args); |
256 | switch (token) { |
257 | case Opt_kmsg_bytes: |
258 | if (!match_int(&args[0], result: &option)) |
259 | pstore_set_kmsg_bytes(option); |
260 | break; |
261 | } |
262 | } |
263 | } |
264 | |
265 | /* |
266 | * Display the mount options in /proc/mounts. |
267 | */ |
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, fmt: ",kmsg_bytes=%lu" , kmsg_bytes); |
272 | return 0; |
273 | } |
274 | |
275 | static int pstore_remount(struct super_block *sb, int *flags, char *data) |
276 | { |
277 | sync_filesystem(sb); |
278 | parse_options(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 | |
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(lock: &pstore_sb_lock); |
302 | return NULL; |
303 | } |
304 | |
305 | root = pstore_sb->s_root; |
306 | inode_lock(inode: d_inode(dentry: root)); |
307 | mutex_unlock(lock: &pstore_sb_lock); |
308 | |
309 | return root; |
310 | } |
311 | |
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(entry: &pos->list); |
326 | rc = simple_unlink(d_inode(dentry: root), pos->dentry); |
327 | if (WARN_ON(rc)) |
328 | break; |
329 | d_drop(dentry: pos->dentry); |
330 | dput(pos->dentry); |
331 | pos->dentry = NULL; |
332 | } |
333 | } |
334 | mutex_unlock(lock: &records_list_lock); |
335 | |
336 | inode_unlock(inode: d_inode(dentry: 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 | */ |
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(sb: 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(buf: name, size: sizeof(name), fmt: "%s-%s-%llu%s" , |
375 | pstore_type_to_name(type: record->type), |
376 | record->psi->name, record->id, |
377 | record->compressed ? ".enc.z" : "" ); |
378 | |
379 | private = kzalloc(size: 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_set_mtime_to_ts(inode, |
394 | ts: inode_set_ctime_to_ts(inode, ts: record->time)); |
395 | |
396 | d_add(dentry, inode); |
397 | |
398 | list_add(new: &private->list, head: &records_list); |
399 | mutex_unlock(lock: &records_list_lock); |
400 | |
401 | return 0; |
402 | |
403 | fail_private: |
404 | free_pstore_private(private); |
405 | fail_inode: |
406 | iput(inode); |
407 | fail: |
408 | mutex_unlock(lock: &records_list_lock); |
409 | return rc; |
410 | } |
411 | |
412 | /* |
413 | * Read all the records from the persistent store. Create |
414 | * files in our filesystem. Don't warn about -EEXIST errors |
415 | * when we are re-scanning the backing store looking to add new |
416 | * error records. |
417 | */ |
418 | void pstore_get_records(int quiet) |
419 | { |
420 | struct dentry *root; |
421 | |
422 | root = psinfo_lock_root(); |
423 | if (!root) |
424 | return; |
425 | |
426 | pstore_get_backend_records(psi: psinfo, root, quiet); |
427 | inode_unlock(inode: d_inode(dentry: root)); |
428 | } |
429 | |
430 | static int pstore_fill_super(struct super_block *sb, void *data, int silent) |
431 | { |
432 | struct inode *inode; |
433 | |
434 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
435 | sb->s_blocksize = PAGE_SIZE; |
436 | sb->s_blocksize_bits = PAGE_SHIFT; |
437 | sb->s_magic = PSTOREFS_MAGIC; |
438 | sb->s_op = &pstore_ops; |
439 | sb->s_time_gran = 1; |
440 | |
441 | parse_options(options: data); |
442 | |
443 | inode = pstore_get_inode(sb); |
444 | if (inode) { |
445 | inode->i_mode = S_IFDIR | 0750; |
446 | inode->i_op = &pstore_dir_inode_operations; |
447 | inode->i_fop = &simple_dir_operations; |
448 | inc_nlink(inode); |
449 | } |
450 | sb->s_root = d_make_root(inode); |
451 | if (!sb->s_root) |
452 | return -ENOMEM; |
453 | |
454 | mutex_lock(&pstore_sb_lock); |
455 | pstore_sb = sb; |
456 | mutex_unlock(lock: &pstore_sb_lock); |
457 | |
458 | pstore_get_records(quiet: 0); |
459 | |
460 | return 0; |
461 | } |
462 | |
463 | static struct dentry *pstore_mount(struct file_system_type *fs_type, |
464 | int flags, const char *dev_name, void *data) |
465 | { |
466 | return mount_single(fs_type, flags, data, fill_super: pstore_fill_super); |
467 | } |
468 | |
469 | static void pstore_kill_sb(struct super_block *sb) |
470 | { |
471 | mutex_lock(&pstore_sb_lock); |
472 | WARN_ON(pstore_sb && pstore_sb != sb); |
473 | |
474 | kill_litter_super(sb); |
475 | pstore_sb = NULL; |
476 | |
477 | mutex_lock(&records_list_lock); |
478 | INIT_LIST_HEAD(list: &records_list); |
479 | mutex_unlock(lock: &records_list_lock); |
480 | |
481 | mutex_unlock(lock: &pstore_sb_lock); |
482 | } |
483 | |
484 | static struct file_system_type pstore_fs_type = { |
485 | .owner = THIS_MODULE, |
486 | .name = "pstore" , |
487 | .mount = pstore_mount, |
488 | .kill_sb = pstore_kill_sb, |
489 | }; |
490 | |
491 | int __init pstore_init_fs(void) |
492 | { |
493 | int err; |
494 | |
495 | /* Create a convenient mount point for people to access pstore */ |
496 | err = sysfs_create_mount_point(parent_kobj: fs_kobj, name: "pstore" ); |
497 | if (err) |
498 | goto out; |
499 | |
500 | err = register_filesystem(&pstore_fs_type); |
501 | if (err < 0) |
502 | sysfs_remove_mount_point(parent_kobj: fs_kobj, name: "pstore" ); |
503 | |
504 | out: |
505 | return err; |
506 | } |
507 | |
508 | void __exit pstore_exit_fs(void) |
509 | { |
510 | unregister_filesystem(&pstore_fs_type); |
511 | sysfs_remove_mount_point(parent_kobj: fs_kobj, name: "pstore" ); |
512 | } |
513 | |