// SPDX-License-Identifier: GPL-2.0-only
/*
* Persistent Storage - ramfs parts.
*
* Copyright (C) 2010 Intel Corporation <[email protected]>
*/
#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 <linux/cleanup.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;
DEFINE_FREE(pstore_iput, struct inode *, if (_T) iput(_T))
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) {
kvfree(private->record->buf);
kfree(private->record->priv);
kfree(private->record);
}
kfree(private);
}
DEFINE_FREE(pstore_private, struct pstore_private *, free_pstore_private(_T));
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 __free(kfree) = NULL;
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)
return NULL;
return_ptr(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;
if (!record->psi->erase)
return -EPERM;
/* Make sure we can't race while removing this file. */
scoped_guard(mutex, &records_list_lock) {
if (!list_empty(&p->list))
list_del_init(&p->list);
else
return -ENOENT;
p->dentry = NULL;
}
scoped_guard(mutex, &record->psi->read_mutex)
record->psi->erase(record);
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();
simple_inode_init_ts(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;
guard(mutex)(&pstore_sb_lock);
/*
* Having no backend is fine -- no records appear.
* Not being mounted is fine -- nothing to do.
*/
if (!psinfo || !pstore_sb)
return NULL;
root = pstore_sb->s_root;
inode_lock(d_inode(root));
return root;
}
int pstore_put_backend_records(struct pstore_info *psi)
{
struct pstore_private *pos, *tmp;
struct dentry *root;
root = psinfo_lock_root();
if (!root)
return 0;
scoped_guard(mutex, &records_list_lock) {
list_for_each_entry_safe(pos, tmp, &records_list, list) {
if (pos->record->psi == psi) {
list_del_init(&pos->list);
d_invalidate(pos->dentry);
simple_unlink(d_inode(root), pos->dentry);
pos->dentry = NULL;
}
}
}
inode_unlock(d_inode(root));
return 0;
}
/*
* 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 __free(pstore_iput) = NULL;
char name[PSTORE_NAMELEN];
struct pstore_private *private __free(pstore_private) = NULL, *pos;
size_t size = record->size + record->ecc_notice_size;
if (WARN_ON(!inode_is_locked(d_inode(root))))
return -EINVAL;
guard(mutex)(&records_list_lock);
/* Skip records that are already present in the filesystem. */
list_for_each_entry(pos, &records_list, list) {
if (pos->record->type == record->type &&
pos->record->id == record->id &&
pos->record->psi == record->psi)
return -EEXIST;
}
inode = pstore_get_inode(root->d_sb);
if (!inode)
return -ENOMEM;
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)
return -ENOMEM;
dentry = d_alloc_name(root, name);
if (!dentry)
return -ENOMEM;
private->dentry = dentry;
private->record = record;
inode->i_size = private->total_size = size;
inode->i_private = private;
if (record->time.tv_sec)
inode_set_mtime_to_ts(inode,
inode_set_ctime_to_ts(inode, record->time));
d_add(dentry, no_free_ptr(inode));
list_add(&(no_free_ptr(private))->list, &records_list);
return 0;
}
/*
* 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;
scoped_guard(mutex, &pstore_sb_lock)
pstore_sb = sb;
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)
{
guard(mutex)(&pstore_sb_lock);
WARN_ON(pstore_sb && pstore_sb != sb);
kill_litter_super(sb);
pstore_sb = NULL;
guard(mutex)(&records_list_lock);
INIT_LIST_HEAD(&records_list);
}
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");
}
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