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1// SPDX-License-Identifier: GPL-2.0-only2/*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 6431 32static DEFINE_MUTEX(records_list_lock);33static LIST_HEAD(records_list);34 35static DEFINE_MUTEX(pstore_sb_lock);36static struct super_block *pstore_sb;37 38DEFINE_FREE(pstore_iput, struct inode *, if (_T) iput(_T))39 40struct pstore_private {41 struct list_head list;42 struct dentry *dentry;43 struct pstore_record *record;44 size_t total_size;45};46 47struct 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 55static 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}66DEFINE_FREE(pstore_private, struct pstore_private *, free_pstore_private(_T));67 68static 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 85static void pstore_ftrace_seq_stop(struct seq_file *s, void *v)86{87 kfree(v);88}89 90static 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 103static 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 123static 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 130static 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 142static 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 162static 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 171static 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 the180 * platform driver to erase the record from persistent store.181 */182static 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 else195 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 205static 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 213static const struct inode_operations pstore_dir_inode_operations = {214 .lookup = simple_lookup,215 .unlink = pstore_unlink,216};217 218static 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 228enum {229 Opt_kmsg_bytes, Opt_err230};231 232static const match_table_t tokens = {233 {Opt_kmsg_bytes, "kmsg_bytes=%u"},234 {Opt_err, NULL}235};236 237static 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 */265static 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 272static 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 280static 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 288static 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 306int 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 */336int 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. Create393 * files in our filesystem. Don't warn about -EEXIST errors394 * when we are re-scanning the backing store looking to add new395 * error records.396 */397void 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 409static 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 441static 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 447static 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 459static 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 466int __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 479out:480 return err;481}482 483void __exit pstore_exit_fs(void)484{485 unregister_filesystem(&pstore_fs_type);486 sysfs_remove_mount_point(fs_kobj, "pstore");487}488