path: root/arch/um/kernel/time.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
 * Copyright (C) 2012-2014 Cisco Systems
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Copyright (C) 2019 Intel Corporation
 */

#include <linux/clockchips.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/threads.h>
#include <asm/irq.h>
#include <asm/param.h>
#include <kern_util.h>
#include <os.h>
#include <linux/delay.h>
#include <linux/time-internal.h>
#include <linux/um_timetravel.h>
#include <shared/init.h>

#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
enum time_travel_mode time_travel_mode;
EXPORT_SYMBOL_GPL(time_travel_mode);

static bool time_travel_start_set;
static unsigned long long time_travel_start;
static unsigned long long time_travel_time;
static unsigned long long time_travel_shm_offset;
static LIST_HEAD(time_travel_events);
static LIST_HEAD(time_travel_irqs);
static unsigned long long time_travel_timer_interval;
static unsigned long long time_travel_next_event;
static struct time_travel_event time_travel_timer_event;
static int time_travel_ext_fd = -1;
static unsigned int time_travel_ext_waiting;
static bool time_travel_ext_prev_request_valid;
static unsigned long long time_travel_ext_prev_request;
static unsigned long long *time_travel_ext_free_until;
static unsigned long long _time_travel_ext_free_until;
static u16 time_travel_shm_id;
static struct um_timetravel_schedshm *time_travel_shm;
static union um_timetravel_schedshm_client *time_travel_shm_client;

static void time_travel_set_time(unsigned long long ns)
{
	if (unlikely(ns < time_travel_time))
		panic("time-travel: time goes backwards %lld -> %lld\n",
		      time_travel_time, ns);
	else if (unlikely(ns >= S64_MAX))
		panic("The system was going to sleep forever, aborting");

	time_travel_time = ns;
}

enum time_travel_message_handling {
	TTMH_IDLE,
	TTMH_POLL,
	TTMH_READ,
	TTMH_READ_START_ACK,
};

static u64 bc_message;
int time_travel_should_print_bc_msg;

void _time_travel_print_bc_msg(void)
{
	time_travel_should_print_bc_msg = 0;
	printk(KERN_INFO "time-travel: received broadcast 0x%llx\n", bc_message);
}

static void time_travel_setup_shm(int fd, u16 id)
{
	u32 len;

	time_travel_shm = os_mmap_rw_shared(fd, sizeof(*time_travel_shm));

	if (!time_travel_shm)
		goto out;

	len = time_travel_shm->len;

	if (time_travel_shm->version != UM_TIMETRAVEL_SCHEDSHM_VERSION ||
	    len < struct_size(time_travel_shm, clients, id + 1)) {
		os_unmap_memory(time_travel_shm, sizeof(*time_travel_shm));
		time_travel_shm = NULL;
		goto out;
	}

	time_travel_shm = os_mremap_rw_shared(time_travel_shm,
					      sizeof(*time_travel_shm),
					      len);
	if (!time_travel_shm)
		goto out;

	time_travel_shm_offset = time_travel_shm->current_time;
	time_travel_shm_client = &time_travel_shm->clients[id];
	time_travel_shm_client->capa |= UM_TIMETRAVEL_SCHEDSHM_CAP_TIME_SHARE;
	time_travel_shm_id = id;
	/* always look at that free_until from now on */
	time_travel_ext_free_until = &time_travel_shm->free_until;
out:
	os_close_file(fd);
}

static void time_travel_handle_message(struct um_timetravel_msg *msg,
				       enum time_travel_message_handling mode)
{
	struct um_timetravel_msg resp = {
		.op = UM_TIMETRAVEL_ACK,
	};
	int ret;

	/*
	 * We can't unlock here, but interrupt signals with a timetravel_handler
	 * (see um_request_irq_tt) get to the timetravel_handler anyway.
	 */
	if (mode != TTMH_READ) {
		BUG_ON(mode == TTMH_IDLE && !irqs_disabled());

		while (os_poll(1, &time_travel_ext_fd) != 0) {
			/* nothing */
		}
	}

	if (unlikely(mode == TTMH_READ_START_ACK)) {
		int fd[UM_TIMETRAVEL_SHARED_MAX_FDS];

		ret = os_rcv_fd_msg(time_travel_ext_fd, fd,
				    ARRAY_SIZE(fd), msg, sizeof(*msg));
		if (ret == sizeof(*msg)) {
			time_travel_setup_shm(fd[UM_TIMETRAVEL_SHARED_MEMFD],
					      msg->time & UM_TIMETRAVEL_START_ACK_ID);
			/* we don't use the logging for now */
			os_close_file(fd[UM_TIMETRAVEL_SHARED_LOGFD]);
		}
	} else {
		ret = os_read_file(time_travel_ext_fd, msg, sizeof(*msg));
	}

	if (ret == 0)
		panic("time-travel external link is broken\n");
	if (ret != sizeof(*msg))
		panic("invalid time-travel message - %d bytes\n", ret);

	switch (msg->op) {
	default:
		WARN_ONCE(1, "time-travel: unexpected message %lld\n",
			  (unsigned long long)msg->op);
		break;
	case UM_TIMETRAVEL_ACK:
		return;
	case UM_TIMETRAVEL_RUN:
		time_travel_set_time(msg->time);
		if (time_travel_shm) {
			/* no request right now since we're running */
			time_travel_shm_client->flags &=
				~UM_TIMETRAVEL_SCHEDSHM_FLAGS_REQ_RUN;
			/* no ack for shared memory RUN */
			return;
		}
		break;
	case UM_TIMETRAVEL_FREE_UNTIL:
		/* not supposed to get this with shm, but ignore it */
		if (time_travel_shm)
			break;
		time_travel_ext_free_until = &_time_travel_ext_free_until;
		_time_travel_ext_free_until = msg->time;
		break;
	case UM_TIMETRAVEL_BROADCAST:
		bc_message = msg->time;
		time_travel_should_print_bc_msg = 1;
		break;
	}

	resp.seq = msg->seq;