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