cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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hypfs_dbfs.c (2097B)

      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
     12static struct dentry *dbfs_dir;
     13
     14static 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
     25static 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
     31static 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
     61static 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
     75static const struct file_operations dbfs_ops = {
     76	.read		= dbfs_read,
     77	.llseek		= no_llseek,
     78	.unlocked_ioctl = dbfs_ioctl,
     79};
     80
     81void 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
     88void hypfs_dbfs_remove_file(struct hypfs_dbfs_file *df)
     89{
     90	debugfs_remove(df->dentry);
     91}
     92
     93void hypfs_dbfs_init(void)
     94{
     95	dbfs_dir = debugfs_create_dir("s390_hypfs", NULL);
     96}
     97
     98void hypfs_dbfs_exit(void)
     99{
    100	debugfs_remove(dbfs_dir);
    101}