// SPDX-License-Identifier: GPL-2.0-only /* * Persistent Storage - ramfs parts. * * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com> */ #include <linux/module.h> #include <linux/fs.h> #include <linux/fsnotify.h> #include <linux/pagemap.h> #include <linux/highmem.h> #include <linux/time.h> #include <linux/init.h> #include <linux/list.h> #include <linux/string.h> #include <linux/mount.h> #include <linux/seq_file.h> #include <linux/ramfs.h> #include <linux/parser.h> #include <linux/sched.h> #include <linux/magic.h> #include <linux/pstore.h> #include <linux/slab.h> #include <linux/uaccess.h> #include "internal.h" #define PSTORE_NAMELEN 64 static DEFINE_MUTEX(records_list_lock); static LIST_HEAD(records_list); static DEFINE_MUTEX(pstore_sb_lock); static struct super_block *pstore_sb; struct pstore_private { struct list_head list; struct dentry *dentry; struct pstore_record *record; size_t total_size; }; struct pstore_ftrace_seq_data { const void *ptr; size_t off; size_t size; }; #define REC_SIZE sizeof(struct pstore_ftrace_record) static void free_pstore_private(struct pstore_private *private) { if (!private) return; if (private->record) { kfree(private->record->buf); kfree(private->record->priv); kfree(private->record); } kfree(private); } static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos) { struct pstore_private *ps = s->private; struct pstore_ftrace_seq_data *data; data = kzalloc(sizeof(*data), GFP_KERNEL); if (!data) return NULL; data->off = ps->total_size % REC_SIZE; data->off += *pos * REC_SIZE; if (data->off + REC_SIZE > ps->total_size) { kfree(data); return NULL; } return data; } static void pstore_ftrace_seq_stop(struct seq_file *s, void *v) { kfree(v); } static void *pstore_ftrace_seq_next(struct seq_file *s, void *v, loff_t *pos) { struct pstore_private *ps = s->private; struct pstore_ftrace_seq_data *data = v; (*pos)++; data->off += REC_SIZE; if (data->off + REC_SIZE > ps->total_size) return NULL; return data; } static int pstore_ftrace_seq_show(struct seq_file *s, void *v) { struct pstore_private *ps = s->private; struct pstore_ftrace_seq_data *data = v; struct pstore_ftrace_record *rec; if (!data) return 0; rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off); seq_printf(s, "CPU:%d ts:%llu %08lx %08lx %ps <- %pS\n", pstore_ftrace_decode_cpu(rec), pstore_ftrace_read_timestamp(rec), rec->ip, rec->parent_ip, (void *)rec->ip, (void *)rec->parent_ip); return 0; } static const struct seq_operations pstore_ftrace_seq_ops = { .start = pstore_ftrace_seq_start, .next = pstore_ftrace_seq_next, .stop = pstore_ftrace_seq_stop, .show = pstore_ftrace_seq_show, }; static ssize_t pstore_file_read(struct file *file, char __user *userbuf, size_t count, loff_t *ppos) { struct seq_file *sf = file->private_data; struct pstore_private *ps = sf->private; if (ps->record->type == PSTORE_TYPE_FTRACE) return seq_read(file, userbuf, count, ppos); return simple_read_from_buffer(userbuf, count, ppos, ps->record->buf, ps->total_size); } static int pstore_file_open(struct inode *inode, struct file *file) { struct pstore_private *ps = inode->i_private; struct seq_file *sf; int err; const struct seq_operations *sops = NULL; if (ps->record->type == PSTORE_TYPE_FTRACE) sops = &pstore_ftrace_seq_ops; err = seq_open(file, sops); if (err < 0) return err; sf = file->private_data; sf->private = ps; return 0; } static loff_t pstore_file_llseek(struct file *file, loff_t off, int whence) { struct seq_file *sf = file->private_data; if (sf->op) return seq_lseek(file, off, whence); return default_llseek(file, off, whence); } static const struct file_operations pstore_file_operations = { .open = pstore_file_open, .read = pstore_file_read, .llseek = pstore_file_llseek, .release = seq_release, }; /* * When a file is unlinked from our file system we call the * platform driver to erase the record from persistent store. */ static int pstore_unlink(struct inode *dir, struct dentry *dentry) { struct pstore_private *p = d_inode(dentry)->i_private; struct pstore_record *record = p->record; int rc = 0; if (!record->psi->erase) return -EPERM; /* Make sure we can't race while removing this file. */ mutex_lock(&records_list_lock); if (!list_empty(&p->list)) list_del_init(&p->list); else rc = -ENOENT; p->dentry = NULL; mutex_unlock(&records_list_lock); if (rc) return rc; mutex_lock(&record->psi->read_mutex); record->psi->erase(record); mutex_unlock(&record->psi->read_mutex); return simple_unlink(dir, dentry); } static void pstore_evict_inode(struct inode *inode) { struct pstore_private *p = inode->i_private; clear_inode(inode); free_pstore_private(p); } static const struct inode_operations pstore_dir_inode_operations = { .lookup = simple_lookup, .unlink = pstore_unlink, }; static struct inode *pstore_get_inode(struct super_block *sb) { struct inode *inode = new_inode(sb); if (inode) { inode->i_ino = get_next_ino(); inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); } return inode; } enum { Opt_kmsg_bytes, Opt_err }; static const match_table_t tokens = { {Opt_kmsg_bytes, "kmsg_bytes=%u"}, {Opt_err, NULL} }; static void parse_options(char *options) { char *p; substring_t args[MAX_OPT_ARGS]; int option; if (!options) return; while ((p = strsep(&options, ",")) != NULL) { int token; if (!*p) continue; token = match_token(p, tokens, args); switch (token) { case Opt_kmsg_bytes: if (!match_int(&args[0], &option)) pstore_set_kmsg_bytes(option); break; } } } /* * Display the mount options in /proc/mounts. */ static int pstore_show_options(struct seq_file *m, struct dentry *root) { if (kmsg_bytes != CONFIG_PSTORE_DEFAULT_KMSG_BYTES) seq_printf(m, ",kmsg_bytes=%lu", kmsg_bytes); return 0; } static int pstore_remount(struct super_block *sb, int *flags, char *data) { sync_filesystem(sb); parse_options(data); return 0; } static const struct super_operations pstore_ops = { .statfs = simple_statfs, .drop_inode = generic_delete_inode, .evict_inode = pstore_evict_inode, .remount_fs = pstore_remount, .show_options = pstore_show_options, }; static struct dentry *psinfo_lock_root(void) { struct dentry *root; mutex_lock(&pstore_sb_lock); /* * Having no backend is fine -- no records appear. * Not being mounted is fine -- nothing to do. */ if (!psinfo || !pstore_sb) { mutex_unlock(&pstore_sb_lock); return NULL; } root = pstore_sb->s_root; inode_lock(d_inode(root)); mutex_unlock(&pstore_sb_lock); return root; } int pstore_put_backend_records(struct pstore_info *psi) { struct pstore_private *pos, *tmp; struct dentry *root; int rc = 0; root = psinfo_lock_root(); if (!root) return 0; mutex_lock(&records_list_lock); list_for_each_entry_safe(pos, tmp, &records_list, list) { if (pos->record->psi == psi) { list_del_init(&pos->list); rc = simple_unlink(d_inode(root), pos->dentry); if (WARN_ON(rc)) break; d_drop(pos->dentry); dput(pos->dentry); pos->dentry = NULL; } } mutex_unlock(&records_list_lock); inode_unlock(d_inode(root)); return rc; } /* * Make a regular file in the root directory of our file system. * Load it up with "size" bytes of data from "buf". * Set the mtime & ctime to the date that this record was originally stored. */ int pstore_mkfile(struct dentry *root, struct pstore_record *record) { struct dentry *dentry; struct inode *inode; int rc = 0; char name[PSTORE_NAMELEN]; struct pstore_private *private, *pos; size_t size = record->size + record->ecc_notice_size; if (WARN_ON(!inode_is_locked(d_inode(root)))) return -EINVAL; rc = -EEXIST; /* Skip records that are already present in the filesystem. */ mutex_lock(&records_list_lock); list_for_each_entry(pos, &records_list, list) { if (pos->record->type == record->type && pos->record->id == record->id && pos->record->psi == record->psi) goto fail; } rc = -ENOMEM; inode = pstore_get_inode(root->d_sb); if (!inode) goto fail; inode->i_mode = S_IFREG | 0444; inode->i_fop = &pstore_file_operations; scnprintf(name, sizeof(name), "%s-%s-%llu%s", pstore_type_to_name(record->type), record->psi->name, record->id, record->compressed ? ".enc.z" : ""); private = kzalloc(sizeof(*private), GFP_KERNEL); if (!private) goto fail_inode; dentry = d_alloc_name(root, name); if (!dentry) goto fail_private; private->dentry = dentry; private->record = record; inode->i_size = private->total_size = size; inode->i_private = private; if (record->time.tv_sec) inode->i_mtime = inode->i_ctime = record->time; d_add(dentry, inode); list_add(&private->list, &records_list); mutex_unlock(&records_list_lock); return 0; fail_private: free_pstore_private(private); fail_inode: iput(inode); fail: mutex_unlock(&records_list_lock); return rc; } /* * Read all the records from the persistent store. Create * files in our filesystem. Don't warn about -EEXIST errors * when we are re-scanning the backing store looking to add new * error records. */ void pstore_get_records(int quiet) { struct dentry *root; root = psinfo_lock_root(); if (!root) return; pstore_get_backend_records(psinfo, root, quiet); inode_unlock(d_inode(root)); } static int pstore_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode; sb->s_maxbytes = MAX_LFS_FILESIZE; sb->s_blocksize = PAGE_SIZE; sb->s_blocksize_bits = PAGE_SHIFT; sb->s_magic = PSTOREFS_MAGIC; sb->s_op = &pstore_ops; sb->s_time_gran = 1; parse_options(data); inode = pstore_get_inode(sb); if (inode) { inode->i_mode = S_IFDIR | 0750; inode->i_op = &pstore_dir_inode_operations; inode->i_fop = &simple_dir_operations; inc_nlink(inode); } sb->s_root = d_make_root(inode); if (!sb->s_root) return -ENOMEM; mutex_lock(&pstore_sb_lock); pstore_sb = sb; mutex_unlock(&pstore_sb_lock); pstore_get_records(0); return 0; } static struct dentry *pstore_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { return mount_single(fs_type, flags, data, pstore_fill_super); } static void pstore_kill_sb(struct super_block *sb) { mutex_lock(&pstore_sb_lock); WARN_ON(pstore_sb && pstore_sb != sb); kill_litter_super(sb); pstore_sb = NULL; mutex_lock(&records_list_lock); INIT_LIST_HEAD(&records_list); mutex_unlock(&records_list_lock); mutex_unlock(&pstore_sb_lock); } static struct file_system_type pstore_fs_type = { .owner = THIS_MODULE, .name = "pstore", .mount = pstore_mount, .kill_sb = pstore_kill_sb, }; int __init pstore_init_fs(void) { int err; /* Create a convenient mount point for people to access pstore */ err = sysfs_create_mount_point(fs_kobj, "pstore"); if (err) goto out; err = register_filesystem(&pstore_fs_type); if (err < 0) sysfs_remove_mount_point(fs_kobj, "pstore"); out: return err; } void __exit pstore_exit_fs(void) { unregister_filesystem(&pstore_fs_type); sysfs_remove_mount_point(fs_kobj, "pstore"); }