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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pdc_cons.c (6942B)


      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/* 
      3 *    PDC Console support - ie use firmware to dump text via boot console
      4 *
      5 *    Copyright (C) 1999-2003 Matthew Wilcox <willy at parisc-linux.org>
      6 *    Copyright (C) 2000 Martin K Petersen <mkp at mkp.net>
      7 *    Copyright (C) 2000 John Marvin <jsm at parisc-linux.org>
      8 *    Copyright (C) 2000-2003 Paul Bame <bame at parisc-linux.org>
      9 *    Copyright (C) 2000 Philipp Rumpf <prumpf with tux.org>
     10 *    Copyright (C) 2000 Michael Ang <mang with subcarrier.org>
     11 *    Copyright (C) 2000 Grant Grundler <grundler with parisc-linux.org>
     12 *    Copyright (C) 2001-2002 Ryan Bradetich <rbrad at parisc-linux.org>
     13 *    Copyright (C) 2001 Helge Deller <deller at parisc-linux.org>
     14 *    Copyright (C) 2001 Thomas Bogendoerfer <tsbogend at parisc-linux.org>
     15 *    Copyright (C) 2002 Randolph Chung <tausq with parisc-linux.org>
     16 *    Copyright (C) 2010 Guy Martin <gmsoft at tuxicoman.be>
     17 */
     18
     19/*
     20 *  The PDC console is a simple console, which can be used for debugging 
     21 *  boot related problems on HP PA-RISC machines. It is also useful when no
     22 *  other console works.
     23 *
     24 *  This code uses the ROM (=PDC) based functions to read and write characters
     25 *  from and to PDC's boot path.
     26 */
     27
     28/* Define EARLY_BOOTUP_DEBUG to debug kernel related boot problems. 
     29 * On production kernels EARLY_BOOTUP_DEBUG should be undefined. */
     30#define EARLY_BOOTUP_DEBUG
     31
     32
     33#include <linux/kernel.h>
     34#include <linux/console.h>
     35#include <linux/string.h>
     36#include <linux/init.h>
     37#include <linux/major.h>
     38#include <linux/tty.h>
     39#include <asm/page.h>		/* for PAGE0 */
     40#include <asm/pdc.h>		/* for iodc_call() proto and friends */
     41
     42static DEFINE_SPINLOCK(pdc_console_lock);
     43static struct console pdc_cons;
     44
     45static void pdc_console_write(struct console *co, const char *s, unsigned count)
     46{
     47	int i = 0;
     48	unsigned long flags;
     49
     50	spin_lock_irqsave(&pdc_console_lock, flags);
     51	do {
     52		i += pdc_iodc_print(s + i, count - i);
     53	} while (i < count);
     54	spin_unlock_irqrestore(&pdc_console_lock, flags);
     55}
     56
     57int pdc_console_poll_key(struct console *co)
     58{
     59	int c;
     60	unsigned long flags;
     61
     62	spin_lock_irqsave(&pdc_console_lock, flags);
     63	c = pdc_iodc_getc();
     64	spin_unlock_irqrestore(&pdc_console_lock, flags);
     65
     66	return c;
     67}
     68
     69static int pdc_console_setup(struct console *co, char *options)
     70{
     71	return 0;
     72}
     73
     74#if defined(CONFIG_PDC_CONSOLE)
     75#include <linux/vt_kern.h>
     76#include <linux/tty_flip.h>
     77
     78#define PDC_CONS_POLL_DELAY (30 * HZ / 1000)
     79
     80static void pdc_console_poll(struct timer_list *unused);
     81static DEFINE_TIMER(pdc_console_timer, pdc_console_poll);
     82static struct tty_port tty_port;
     83
     84static int pdc_console_tty_open(struct tty_struct *tty, struct file *filp)
     85{
     86	tty_port_tty_set(&tty_port, tty);
     87	mod_timer(&pdc_console_timer, jiffies + PDC_CONS_POLL_DELAY);
     88
     89	return 0;
     90}
     91
     92static void pdc_console_tty_close(struct tty_struct *tty, struct file *filp)
     93{
     94	if (tty->count == 1) {
     95		del_timer_sync(&pdc_console_timer);
     96		tty_port_tty_set(&tty_port, NULL);
     97	}
     98}
     99
    100static int pdc_console_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
    101{
    102	pdc_console_write(NULL, buf, count);
    103	return count;
    104}
    105
    106static unsigned int pdc_console_tty_write_room(struct tty_struct *tty)
    107{
    108	return 32768; /* no limit, no buffer used */
    109}
    110
    111static const struct tty_operations pdc_console_tty_ops = {
    112	.open = pdc_console_tty_open,
    113	.close = pdc_console_tty_close,
    114	.write = pdc_console_tty_write,
    115	.write_room = pdc_console_tty_write_room,
    116};
    117
    118static void pdc_console_poll(struct timer_list *unused)
    119{
    120	int data, count = 0;
    121
    122	while (1) {
    123		data = pdc_console_poll_key(NULL);
    124		if (data == -1)
    125			break;
    126		tty_insert_flip_char(&tty_port, data & 0xFF, TTY_NORMAL);
    127		count ++;
    128	}
    129
    130	if (count)
    131		tty_flip_buffer_push(&tty_port);
    132
    133	if (pdc_cons.flags & CON_ENABLED)
    134		mod_timer(&pdc_console_timer, jiffies + PDC_CONS_POLL_DELAY);
    135}
    136
    137static struct tty_driver *pdc_console_tty_driver;
    138
    139static int __init pdc_console_tty_driver_init(void)
    140{
    141	struct tty_driver *driver;
    142	int err;
    143
    144	/* Check if the console driver is still registered.
    145	 * It is unregistered if the pdc console was not selected as the
    146	 * primary console. */
    147
    148	struct console *tmp;
    149
    150	console_lock();
    151	for_each_console(tmp)
    152		if (tmp == &pdc_cons)
    153			break;
    154	console_unlock();
    155
    156	if (!tmp) {
    157		printk(KERN_INFO "PDC console driver not registered anymore, not creating %s\n", pdc_cons.name);
    158		return -ENODEV;
    159	}
    160
    161	printk(KERN_INFO "The PDC console driver is still registered, removing CON_BOOT flag\n");
    162	pdc_cons.flags &= ~CON_BOOT;
    163
    164	driver = tty_alloc_driver(1, TTY_DRIVER_REAL_RAW |
    165			TTY_DRIVER_RESET_TERMIOS);
    166	if (IS_ERR(driver))
    167		return PTR_ERR(driver);
    168
    169	tty_port_init(&tty_port);
    170
    171	driver->driver_name = "pdc_cons";
    172	driver->name = "ttyB";
    173	driver->major = MUX_MAJOR;
    174	driver->minor_start = 0;
    175	driver->type = TTY_DRIVER_TYPE_SYSTEM;
    176	driver->init_termios = tty_std_termios;
    177	tty_set_operations(driver, &pdc_console_tty_ops);
    178	tty_port_link_device(&tty_port, driver, 0);
    179
    180	err = tty_register_driver(driver);
    181	if (err) {
    182		printk(KERN_ERR "Unable to register the PDC console TTY driver\n");
    183		tty_port_destroy(&tty_port);
    184		tty_driver_kref_put(driver);
    185		return err;
    186	}
    187
    188	pdc_console_tty_driver = driver;
    189
    190	return 0;
    191}
    192device_initcall(pdc_console_tty_driver_init);
    193
    194static struct tty_driver * pdc_console_device (struct console *c, int *index)
    195{
    196	*index = c->index;
    197	return pdc_console_tty_driver;
    198}
    199#else
    200#define pdc_console_device NULL
    201#endif
    202
    203static struct console pdc_cons = {
    204	.name =		"ttyB",
    205	.write =	pdc_console_write,
    206	.device =	pdc_console_device,
    207	.setup =	pdc_console_setup,
    208	.flags =	CON_BOOT | CON_PRINTBUFFER,
    209	.index =	-1,
    210};
    211
    212static int pdc_console_initialized;
    213
    214static void pdc_console_init_force(void)
    215{
    216	if (pdc_console_initialized)
    217		return;
    218	++pdc_console_initialized;
    219	
    220	/* If the console is duplex then copy the COUT parameters to CIN. */
    221	if (PAGE0->mem_cons.cl_class == CL_DUPLEX)
    222		memcpy(&PAGE0->mem_kbd, &PAGE0->mem_cons, sizeof(PAGE0->mem_cons));
    223
    224	/* register the pdc console */
    225	register_console(&pdc_cons);
    226}
    227
    228void __init pdc_console_init(void)
    229{
    230#if defined(EARLY_BOOTUP_DEBUG) || defined(CONFIG_PDC_CONSOLE)
    231	pdc_console_init_force();
    232#endif
    233#ifdef EARLY_BOOTUP_DEBUG
    234	printk(KERN_INFO "Initialized PDC Console for debugging.\n");
    235#endif
    236}
    237
    238
    239/*
    240 * Used for emergencies. Currently only used if an HPMC occurs. If an
    241 * HPMC occurs, it is possible that the current console may not be
    242 * properly initialised after the PDC IO reset. This routine unregisters
    243 * all of the current consoles, reinitializes the pdc console and
    244 * registers it.
    245 */
    246
    247void pdc_console_restart(void)
    248{
    249	struct console *console;
    250
    251	if (pdc_console_initialized)
    252		return;
    253
    254	/* If we've already seen the output, don't bother to print it again */
    255	if (console_drivers != NULL)
    256		pdc_cons.flags &= ~CON_PRINTBUFFER;
    257
    258	while ((console = console_drivers) != NULL)
    259		unregister_console(console_drivers);
    260
    261	/* force registering the pdc console */
    262	pdc_console_init_force();
    263}