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 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 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 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 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 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 88 void hypfs_dbfs_remove_file(struct hypfs_dbfs_file *df) 89 { 90 debugfs_remove(df->dentry); 91 } 92 93 void hypfs_dbfs_init(void) 94 { 95 dbfs_dir = debugfs_create_dir("s390_hypfs", NULL); 96 } 97 98 void hypfs_dbfs_exit(void) 99 { 100 debugfs_remove(dbfs_dir); 101 } 102