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 kfree(private->record->buf); 58 kfree(private->record->priv); 59 kfree(private->record); 60 } 61 kfree(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(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 84 static void pstore_ftrace_seq_stop(struct seq_file *s, void *v) 85 { 86 kfree(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(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 }; 128 129 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 } 140 141 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, 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(&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 } 207 208 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 }; 220 221 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 }; 239 240 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 */ 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 } 274 275 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 }; 290 291 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 } 311 312 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 */ 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 */ 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 } 428 429 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 } 461 462 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 } 467 468 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 }; 489 490 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 } 506 507 void __exit pstore_exit_fs(void) 508 { 509 unregister_filesystem(&pstore_fs_type); 510 sysfs_remove_mount_point(fs_kobj, "pstore"); 511 } 512