1 files changed, 528 insertions, 0 deletions
diff --git a/fs/pstore/inode.c b/fs/pstore/inode.c
new file mode 100644
index 000000000..cf499ba72
--- /dev/null
+++ b/fs/pstore/inode.c
@@ -0,0 +1,528 @@
+// 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/seq_file.h>
+#include <linux/ramfs.h>
+#include <linux/fs_parser.h>
+#include <linux/fs_context.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_obj(*data);
+	if (!data)
+		return NULL;
+
+	data->off = ps->record->size % REC_SIZE;
+	data->off += *pos * REC_SIZE;
+	if (data->off + REC_SIZE > ps->record->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->record->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;
+	unsigned long ip, parent_ip;
+
+	if (!data)
+		return 0;
+
+	rec = (struct pstore_ftrace_record *)(ps->record->buf + data->off);
+
+	ip = decode_ip(rec->ip);
+	parent_ip = decode_ip(rec->parent_ip);
+	seq_printf(s, "CPU:%d ts:%llu %08lx  %08lx  %ps <- %pS\n",
+		   pstore_ftrace_decode_cpu(rec),
+		   pstore_ftrace_read_timestamp(rec),
+		   ip, parent_ip, (void *)ip, (void *)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
+};
+
+static const struct fs_parameter_spec pstore_param_spec[] = {
+	fsparam_u32	("kmsg_bytes",	Opt_kmsg_bytes),
+	{}
+};
+
+struct pstore_context {
+	unsigned int kmsg_bytes;
+};
+
+static int pstore_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct pstore_context *ctx = fc->fs_private;
+	struct fs_parse_result result;
+	int opt;
+
+	opt = fs_parse(fc, pstore_param_spec, param, &result);
+	/* pstore has historically ignored invalid kmsg_bytes param */
+	if (opt < 0)
+		return 0;
+
+	switch (opt) {
+	case Opt_kmsg_bytes:
+		ctx->kmsg_bytes = result.uint_32;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * 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=%u", kmsg_bytes);
+	return 0;
+}
+
+static int pstore_reconfigure(struct fs_context *fc)
+{
+	struct pstore_context *ctx = fc->fs_private;
+
+	sync_filesystem(fc->root->d_sb);
+	pstore_set_kmsg_bytes(ctx->kmsg_bytes);
+
+	return 0;
+}
+
+static const struct super_operations pstore_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= inode_just_drop,
+	.evict_inode	= pstore_evict_inode,
+	.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_nested(d_inode(root), I_MUTEX_PARENT);
+
+	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);
+				locked_recursive_removal(pos->dentry, NULL);
+				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_obj(*private);
+	if (!private)
+		return -ENOMEM;
+
+	dentry = d_alloc_name(root, name);
+	if (!dentry)
+		return -ENOMEM;
+
+	private->dentry = dentry; // borrowed
+	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_make_persistent(dentry, no_free_ptr(inode));
+	dput(dentry);
+
+	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, struct fs_context *fc)
+{
+	struct pstore_context *ctx = fc->fs_private;
+	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;
+
+	pstore_set_kmsg_bytes(ctx->kmsg_bytes);
+
+	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 int pstore_get_tree(struct fs_context *fc)
+{
+	if (fc->root)
+		return pstore_reconfigure(fc);
+
+	return get_tree_single(fc, pstore_fill_super);
+}
+
+static void pstore_free_fc(struct fs_context *fc)
+{
+	kfree(fc->fs_private);
+}
+
+static const struct fs_context_operations pstore_context_ops = {
+	.parse_param	= pstore_parse_param,
+	.get_tree	= pstore_get_tree,
+	.reconfigure	= pstore_reconfigure,
+	.free		= pstore_free_fc,
+};
+
+static void pstore_kill_sb(struct super_block *sb)
+{
+	guard(mutex)(&pstore_sb_lock);
+	WARN_ON(pstore_sb && pstore_sb != sb);
+
+	kill_anon_super(sb);
+	pstore_sb = NULL;
+
+	guard(mutex)(&records_list_lock);
+	INIT_LIST_HEAD(&records_list);
+}
+
+static int pstore_init_fs_context(struct fs_context *fc)
+{
+	struct pstore_context *ctx;
+
+	ctx = kzalloc_obj(struct pstore_context);
+	if (!ctx)
+		return -ENOMEM;
+
+	/*
+	 * Global kmsg_bytes is initialized to default, and updated
+	 * every time we (re)mount the single-sb filesystem with the
+	 * option specified.
+	 */
+	ctx->kmsg_bytes = kmsg_bytes;
+
+	fc->fs_private = ctx;
+	fc->ops = &pstore_context_ops;
+
+	return 0;
+}
+
+static struct file_system_type pstore_fs_type = {
+	.owner          = THIS_MODULE,
+	.name		= "pstore",
+	.kill_sb	= pstore_kill_sb,
+	.init_fs_context = pstore_init_fs_context,
+	.parameters	= pstore_param_spec,
+};
+
+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");
+}