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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super.c (2691B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 *  xenfs.c - a filesystem for passing info between the a domain and
      4 *  the hypervisor.
      5 *
      6 * 2008-10-07  Alex Zeffertt    Replaced /proc/xen/xenbus with xenfs filesystem
      7 *                              and /proc/xen compatibility mount point.
      8 *                              Turned xenfs into a loadable module.
      9 */
     10
     11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
     12
     13#include <linux/kernel.h>
     14#include <linux/errno.h>
     15#include <linux/module.h>
     16#include <linux/fs.h>
     17#include <linux/fs_context.h>
     18#include <linux/magic.h>
     19
     20#include <xen/xen.h>
     21#include <xen/xenbus.h>
     22
     23#include "xenfs.h"
     24#include "../privcmd.h"
     25
     26#include <asm/xen/hypervisor.h>
     27
     28MODULE_DESCRIPTION("Xen filesystem");
     29MODULE_LICENSE("GPL");
     30
     31static ssize_t capabilities_read(struct file *file, char __user *buf,
     32				 size_t size, loff_t *off)
     33{
     34	char *tmp = "";
     35
     36	if (xen_initial_domain())
     37		tmp = "control_d\n";
     38
     39	return simple_read_from_buffer(buf, size, off, tmp, strlen(tmp));
     40}
     41
     42static const struct file_operations capabilities_file_ops = {
     43	.read = capabilities_read,
     44	.llseek = default_llseek,
     45};
     46
     47static int xenfs_fill_super(struct super_block *sb, struct fs_context *fc)
     48{
     49	static const struct tree_descr xenfs_files[] = {
     50		[2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
     51		{ "capabilities", &capabilities_file_ops, S_IRUGO },
     52		{ "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
     53		{""},
     54	};
     55
     56	static const struct tree_descr xenfs_init_files[] = {
     57		[2] = { "xenbus", &xen_xenbus_fops, S_IRUSR|S_IWUSR },
     58		{ "capabilities", &capabilities_file_ops, S_IRUGO },
     59		{ "privcmd", &xen_privcmd_fops, S_IRUSR|S_IWUSR },
     60		{ "xsd_kva", &xsd_kva_file_ops, S_IRUSR|S_IWUSR},
     61		{ "xsd_port", &xsd_port_file_ops, S_IRUSR|S_IWUSR},
     62#ifdef CONFIG_XEN_SYMS
     63		{ "xensyms", &xensyms_ops, S_IRUSR},
     64#endif
     65		{""},
     66	};
     67
     68	return simple_fill_super(sb, XENFS_SUPER_MAGIC,
     69			xen_initial_domain() ? xenfs_init_files : xenfs_files);
     70}
     71
     72static int xenfs_get_tree(struct fs_context *fc)
     73{
     74	return get_tree_single(fc, xenfs_fill_super);
     75}
     76
     77static const struct fs_context_operations xenfs_context_ops = {
     78	.get_tree	= xenfs_get_tree,
     79};
     80
     81static int xenfs_init_fs_context(struct fs_context *fc)
     82{
     83	fc->ops = &xenfs_context_ops;
     84	return 0;
     85}
     86
     87static struct file_system_type xenfs_type = {
     88	.owner =	THIS_MODULE,
     89	.name =		"xenfs",
     90	.init_fs_context = xenfs_init_fs_context,
     91	.kill_sb =	kill_litter_super,
     92};
     93MODULE_ALIAS_FS("xenfs");
     94
     95static int __init xenfs_init(void)
     96{
     97	if (xen_domain())
     98		return register_filesystem(&xenfs_type);
     99
    100	return 0;
    101}
    102
    103static void __exit xenfs_exit(void)
    104{
    105	if (xen_domain())
    106		unregister_filesystem(&xenfs_type);
    107}
    108
    109module_init(xenfs_init);
    110module_exit(xenfs_exit);
    111