hypfs_dbfs.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Hypervisor filesystem for Linux on s390 - debugfs interface
  4 *
  5 * Copyright IBM Corp. 2010
  6 * Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com>
  7 */
  8
  9#include <linux/security.h>
 10#include <linux/slab.h>
 11#include "hypfs.h"
 12
 13static struct dentry *dbfs_dir;
 14
 15static struct hypfs_dbfs_data *hypfs_dbfs_data_alloc(struct hypfs_dbfs_file *f)
 16{
 17	struct hypfs_dbfs_data *data;
 18
 19	data = kmalloc(sizeof(*data), GFP_KERNEL);
 20	if (!data)
 21		return NULL;
 22	data->dbfs_file = f;
 23	return data;
 24}
 25
 26static void hypfs_dbfs_data_free(struct hypfs_dbfs_data *data)
 27{
 28	data->dbfs_file->data_free(data->buf_free_ptr);
 29	kfree(data);
 30}
 31
 32static ssize_t dbfs_read(struct file *file, char __user *buf,
 33			 size_t size, loff_t *ppos)
 34{
 35	struct hypfs_dbfs_data *data;
 36	struct hypfs_dbfs_file *df;
 37	ssize_t rc;
 38
 39	if (*ppos != 0)
 40		return 0;
 41
 42	df = file_inode(file)->i_private;
 43	if (mutex_lock_interruptible(&df->lock))
 44		return -ERESTARTSYS;
 45
 46	data = hypfs_dbfs_data_alloc(df);
 47	if (!data) {
 48		mutex_unlock(&df->lock);
 49		return -ENOMEM;
 50	}
 51	rc = df->data_create(&data->buf, &data->buf_free_ptr, &data->size);
 52	if (rc) {
 53		mutex_unlock(&df->lock);
 54		kfree(data);
 55		return rc;
 56	}
 57	mutex_unlock(&df->lock);
 58
 59	rc = simple_read_from_buffer(buf, size, ppos, data->buf, data->size);
 60	hypfs_dbfs_data_free(data);
 61	return rc;
 62}
 63
 64static long dbfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 65{
 66	struct hypfs_dbfs_file *df = file_inode(file)->i_private;
 67	long rc;
 68
 69	mutex_lock(&df->lock);
 70	rc = df->unlocked_ioctl(file, cmd, arg);
 71	mutex_unlock(&df->lock);
 72	return rc;
 73}
 74
 75static const struct file_operations dbfs_ops_ioctl = {
 76	.read		= dbfs_read,
 77	.unlocked_ioctl = dbfs_ioctl,
 78};
 79
 80static const struct file_operations dbfs_ops = {
 81	.read		= dbfs_read,
 82};
 83
 84void hypfs_dbfs_create_file(struct hypfs_dbfs_file *df)
 85{
 86	const struct file_operations *fops = &dbfs_ops;
 87
 88	if (df->unlocked_ioctl && !security_locked_down(LOCKDOWN_DEBUGFS))
 89		fops = &dbfs_ops_ioctl;
 90	df->dentry = debugfs_create_file(df->name, 0400, dbfs_dir, df, fops);
 91	mutex_init(&df->lock);
 92}
 93
 94void hypfs_dbfs_remove_file(struct hypfs_dbfs_file *df)
 95{
 96	debugfs_remove(df->dentry);
 97}
 98
 99static int __init hypfs_dbfs_init(void)
100{
101	int rc = -ENODATA;
102
103	dbfs_dir = debugfs_create_dir("s390_hypfs", NULL);
104	if (hypfs_diag_init())
105		goto fail_dbfs_exit;
106	if (hypfs_vm_init())
107		goto fail_hypfs_diag_exit;
108	hypfs_sprp_init();
109	if (hypfs_diag0c_init())
110		goto fail_hypfs_sprp_exit;
111	rc = hypfs_fs_init();
112	if (rc)
113		goto fail_hypfs_diag0c_exit;
114	return 0;
115
116fail_hypfs_diag0c_exit:
117	hypfs_diag0c_exit();
118fail_hypfs_sprp_exit:
119	hypfs_sprp_exit();
120	hypfs_vm_exit();
121fail_hypfs_diag_exit:
122	hypfs_diag_exit();
123	pr_err("Initialization of hypfs failed with rc=%i\n", rc);
124fail_dbfs_exit:
125	debugfs_remove(dbfs_dir);
126	return rc;
127}
128device_initcall(hypfs_dbfs_init)