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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ttynull.c (2386B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Copyright (C) 2019 Axis Communications AB
      4 *
      5 * Based on ttyprintk.c:
      6 *  Copyright (C) 2010 Samo Pogacnik
      7 */
      8
      9#include <linux/console.h>
     10#include <linux/module.h>
     11#include <linux/tty.h>
     12
     13static const struct tty_port_operations ttynull_port_ops;
     14static struct tty_driver *ttynull_driver;
     15static struct tty_port ttynull_port;
     16
     17static int ttynull_open(struct tty_struct *tty, struct file *filp)
     18{
     19	return tty_port_open(&ttynull_port, tty, filp);
     20}
     21
     22static void ttynull_close(struct tty_struct *tty, struct file *filp)
     23{
     24	tty_port_close(&ttynull_port, tty, filp);
     25}
     26
     27static void ttynull_hangup(struct tty_struct *tty)
     28{
     29	tty_port_hangup(&ttynull_port);
     30}
     31
     32static int ttynull_write(struct tty_struct *tty, const unsigned char *buf,
     33			 int count)
     34{
     35	return count;
     36}
     37
     38static unsigned int ttynull_write_room(struct tty_struct *tty)
     39{
     40	return 65536;
     41}
     42
     43static const struct tty_operations ttynull_ops = {
     44	.open = ttynull_open,
     45	.close = ttynull_close,
     46	.hangup = ttynull_hangup,
     47	.write = ttynull_write,
     48	.write_room = ttynull_write_room,
     49};
     50
     51static struct tty_driver *ttynull_device(struct console *c, int *index)
     52{
     53	*index = 0;
     54	return ttynull_driver;
     55}
     56
     57static struct console ttynull_console = {
     58	.name = "ttynull",
     59	.device = ttynull_device,
     60};
     61
     62static int __init ttynull_init(void)
     63{
     64	struct tty_driver *driver;
     65	int ret;
     66
     67	driver = tty_alloc_driver(1,
     68		TTY_DRIVER_RESET_TERMIOS |
     69		TTY_DRIVER_REAL_RAW |
     70		TTY_DRIVER_UNNUMBERED_NODE);
     71	if (IS_ERR(driver))
     72		return PTR_ERR(driver);
     73
     74	tty_port_init(&ttynull_port);
     75	ttynull_port.ops = &ttynull_port_ops;
     76
     77	driver->driver_name = "ttynull";
     78	driver->name = "ttynull";
     79	driver->type = TTY_DRIVER_TYPE_CONSOLE;
     80	driver->init_termios = tty_std_termios;
     81	driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET;
     82	tty_set_operations(driver, &ttynull_ops);
     83	tty_port_link_device(&ttynull_port, driver, 0);
     84
     85	ret = tty_register_driver(driver);
     86	if (ret < 0) {
     87		tty_driver_kref_put(driver);
     88		tty_port_destroy(&ttynull_port);
     89		return ret;
     90	}
     91
     92	ttynull_driver = driver;
     93	register_console(&ttynull_console);
     94
     95	return 0;
     96}
     97
     98static void __exit ttynull_exit(void)
     99{
    100	unregister_console(&ttynull_console);
    101	tty_unregister_driver(ttynull_driver);
    102	tty_driver_kref_put(ttynull_driver);
    103	tty_port_destroy(&ttynull_port);
    104}
    105
    106module_init(ttynull_init);
    107module_exit(ttynull_exit);
    108
    109MODULE_LICENSE("GPL v2");