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/slab.h>
10 #include "hypfs.h"
11 
12 static struct dentry *dbfs_dir;
13 
hypfs_dbfs_data_alloc(struct hypfs_dbfs_file * f)14 static struct hypfs_dbfs_data *hypfs_dbfs_data_alloc(struct hypfs_dbfs_file *f)
15 {
16 	struct hypfs_dbfs_data *data;
17 
18 	data = kmalloc(sizeof(*data), GFP_KERNEL);
19 	if (!data)
20 		return NULL;
21 	data->dbfs_file = f;
22 	return data;
23 }
24 
hypfs_dbfs_data_free(struct hypfs_dbfs_data * data)25 static void hypfs_dbfs_data_free(struct hypfs_dbfs_data *data)
26 {
27 	data->dbfs_file->data_free(data->buf_free_ptr);
28 	kfree(data);
29 }
30 
dbfs_read(struct file * file,char __user * buf,size_t size,loff_t * ppos)31 static ssize_t dbfs_read(struct file *file, char __user *buf,
32 			 size_t size, loff_t *ppos)
33 {
34 	struct hypfs_dbfs_data *data;
35 	struct hypfs_dbfs_file *df;
36 	ssize_t rc;
37 
38 	if (*ppos != 0)
39 		return 0;
40 
41 	df = file_inode(file)->i_private;
42 	mutex_lock(&df->lock);
43 	data = hypfs_dbfs_data_alloc(df);
44 	if (!data) {
45 		mutex_unlock(&df->lock);
46 		return -ENOMEM;
47 	}
48 	rc = df->data_create(&data->buf, &data->buf_free_ptr, &data->size);
49 	if (rc) {
50 		mutex_unlock(&df->lock);
51 		kfree(data);
52 		return rc;
53 	}
54 	mutex_unlock(&df->lock);
55 
56 	rc = simple_read_from_buffer(buf, size, ppos, data->buf, data->size);
57 	hypfs_dbfs_data_free(data);
58 	return rc;
59 }
60 
dbfs_ioctl(struct file * file,unsigned int cmd,unsigned long arg)61 static long dbfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
62 {
63 	struct hypfs_dbfs_file *df = file_inode(file)->i_private;
64 	long rc;
65 
66 	mutex_lock(&df->lock);
67 	if (df->unlocked_ioctl)
68 		rc = df->unlocked_ioctl(file, cmd, arg);
69 	else
70 		rc = -ENOTTY;
71 	mutex_unlock(&df->lock);
72 	return rc;
73 }
74 
75 static const struct file_operations dbfs_ops = {
76 	.read		= dbfs_read,
77 	.llseek		= no_llseek,
78 	.unlocked_ioctl = dbfs_ioctl,
79 };
80 
hypfs_dbfs_create_file(struct hypfs_dbfs_file * df)81 void hypfs_dbfs_create_file(struct hypfs_dbfs_file *df)
82 {
83 	df->dentry = debugfs_create_file(df->name, 0400, dbfs_dir, df,
84 					 &dbfs_ops);
85 	mutex_init(&df->lock);
86 }
87 
hypfs_dbfs_remove_file(struct hypfs_dbfs_file * df)88 void hypfs_dbfs_remove_file(struct hypfs_dbfs_file *df)
89 {
90 	debugfs_remove(df->dentry);
91 }
92 
hypfs_dbfs_init(void)93 void hypfs_dbfs_init(void)
94 {
95 	dbfs_dir = debugfs_create_dir("s390_hypfs", NULL);
96 }
97 
hypfs_dbfs_exit(void)98 void hypfs_dbfs_exit(void)
99 {
100 	debugfs_remove(dbfs_dir);
101 }
102