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(private->record->buf);
61 kfree(private->record->priv);
62 kfree(private->record);
63 }
64 kfree(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(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(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(s, "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(userbuf, count, ppos,
139 ps->record->buf, 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, 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(&p->list))
193 list_del_init(&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(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, tokens, args);
253 switch (token) {
254 case Opt_kmsg_bytes:
255 if (!match_int(&args[0], &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, ",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(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)(&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(d_inode(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(&pos->list);
319 d_invalidate(pos->dentry);
320 simple_unlink(d_inode(root), pos->dentry);
321 pos->dentry = NULL;
322 }
323 }
324 }
325
326 inode_unlock(d_inode(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)(&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(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(name, sizeof(name), "%s-%s-%llu%s",
363 pstore_type_to_name(record->type),
364 record->psi->name, record->id,
365 record->compressed ? ".enc.z" : "");
366
367 private = kzalloc(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 inode_set_ctime_to_ts(inode, record->time));
383
384 d_add(dentry, no_free_ptr(inode));
385
386 list_add(&(no_free_ptr(private))->list, &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(psinfo, root, quiet);
406 inode_unlock(d_inode(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(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(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, pstore_fill_super);
445 }
446
447 static void pstore_kill_sb(struct super_block *sb)
448 {
449 guard(mutex)(&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)(&records_list_lock);
456 INIT_LIST_HEAD(&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(fs_kobj, "pstore");
472 if (err)
473 goto out;
474
475 err = register_filesystem(&pstore_fs_type);
476 if (err < 0)
477 sysfs_remove_mount_point(fs_kobj, "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(fs_kobj, "pstore");
487 }
488
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