summaryrefslogtreecommitdiffstats
path: root/arch/um/kernel/time.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/um/kernel/time.c')
-rw-r--r--arch/um/kernel/time.c860
1 files changed, 860 insertions, 0 deletions
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
new file mode 100644
index 000000000..fddd1dec2
--- /dev/null
+++ b/arch/um/kernel/time.c
@@ -0,0 +1,860 @@
+// 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/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 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 bool time_travel_ext_free_until_valid;
+static unsigned long long time_travel_ext_free_until;
+
+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,
+};
+
+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 */
+ }
+ }
+
+ 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);
+ break;
+ case UM_TIMETRAVEL_FREE_UNTIL:
+ time_travel_ext_free_until_valid = true;
+ time_travel_ext_free_until = msg->time;
+ break;
+ }
+
+ resp.seq = msg->seq;
+ os_write_file(time_travel_ext_fd, &resp, sizeof(resp));
+}
+
+static u64 time_travel_ext_req(u32 op, u64 time)
+{
+ static int seq;
+ int mseq = ++seq;
+ struct um_timetravel_msg msg = {
+ .op = op,
+ .time = time,
+ .seq = mseq,
+ };
+
+ /*
+ * We need to block even the timetravel handlers of SIGIO here and
+ * only restore their use when we got the ACK - otherwise we may
+ * (will) get interrupted by that, try to queue the IRQ for future
+ * processing and thus send another request while we're still waiting
+ * for an ACK, but the peer doesn't know we got interrupted and will
+ * send the ACKs in the same order as the message, but we'd need to
+ * see them in the opposite order ...
+ *
+ * This wouldn't matter *too* much, but some ACKs carry the
+ * current time (for UM_TIMETRAVEL_GET) and getting another
+ * ACK without a time would confuse us a lot!
+ *
+ * The sequence number assignment that happens here lets us
+ * debug such message handling issues more easily.
+ */
+ block_signals_hard();
+ os_write_file(time_travel_ext_fd, &msg, sizeof(msg));
+
+ while (msg.op != UM_TIMETRAVEL_ACK)
+ time_travel_handle_message(&msg, TTMH_READ);
+
+ if (msg.seq != mseq)
+ panic("time-travel: ACK message has different seqno! op=%d, seq=%d != %d time=%lld\n",
+ msg.op, msg.seq, mseq, msg.time);
+
+ if (op == UM_TIMETRAVEL_GET)
+ time_travel_set_time(msg.time);
+ unblock_signals_hard();
+
+ return msg.time;
+}
+
+void __time_travel_wait_readable(int fd)
+{
+ int fds[2] = { fd, time_travel_ext_fd };
+ int ret;
+
+ if (time_travel_mode != TT_MODE_EXTERNAL)
+ return;
+
+ while ((ret = os_poll(2, fds))) {
+ struct um_timetravel_msg msg;
+
+ if (ret == 1)
+ time_travel_handle_message(&msg, TTMH_READ);
+ }
+}
+EXPORT_SYMBOL_GPL(__time_travel_wait_readable);
+
+static void time_travel_ext_update_request(unsigned long long time)
+{
+ if (time_travel_mode != TT_MODE_EXTERNAL)
+ return;
+
+ /* asked for exactly this time previously */
+ if (time_travel_ext_prev_request_valid &&
+ time == time_travel_ext_prev_request)
+ return;
+
+ /*
+ * if we're running and are allowed to run past the request
+ * then we don't need to update it either
+ */
+ if (!time_travel_ext_waiting && time_travel_ext_free_until_valid &&
+ time < time_travel_ext_free_until)
+ return;
+
+ time_travel_ext_prev_request = time;
+ time_travel_ext_prev_request_valid = true;
+ time_travel_ext_req(UM_TIMETRAVEL_REQUEST, time);
+}
+
+void __time_travel_propagate_time(void)
+{
+ static unsigned long long last_propagated;
+
+ if (last_propagated == time_travel_time)
+ return;
+
+ time_travel_ext_req(UM_TIMETRAVEL_UPDATE, time_travel_time);
+ last_propagated = time_travel_time;
+}
+EXPORT_SYMBOL_GPL(__time_travel_propagate_time);
+
+/* returns true if we must do a wait to the simtime device */
+static bool time_travel_ext_request(unsigned long long time)
+{
+ /*
+ * If we received an external sync point ("free until") then we
+ * don't have to request/wait for anything until then, unless
+ * we're already waiting.
+ */
+ if (!time_travel_ext_waiting && time_travel_ext_free_until_valid &&
+ time < time_travel_ext_free_until)
+ return false;
+
+ time_travel_ext_update_request(time);
+ return true;
+}
+
+static void time_travel_ext_wait(bool idle)
+{
+ struct um_timetravel_msg msg = {
+ .op = UM_TIMETRAVEL_ACK,
+ };
+
+ time_travel_ext_prev_request_valid = false;
+ time_travel_ext_free_until_valid = false;
+ time_travel_ext_waiting++;
+
+ time_travel_ext_req(UM_TIMETRAVEL_WAIT, -1);
+
+ /*
+ * Here we are deep in the idle loop, so we have to break out of the
+ * kernel abstraction in a sense and implement this in terms of the
+ * UML system waiting on the VQ interrupt while sleeping, when we get
+ * the signal it'll call time_travel_ext_vq_notify_done() completing the
+ * call.
+ */
+ while (msg.op != UM_TIMETRAVEL_RUN)
+ time_travel_handle_message(&msg, idle ? TTMH_IDLE : TTMH_POLL);
+
+ time_travel_ext_waiting--;
+
+ /* we might request more stuff while polling - reset when we run */
+ time_travel_ext_prev_request_valid = false;
+}
+
+static void time_travel_ext_get_time(void)
+{
+ time_travel_ext_req(UM_TIMETRAVEL_GET, -1);
+}
+
+static void __time_travel_update_time(unsigned long long ns, bool idle)
+{
+ if (time_travel_mode == TT_MODE_EXTERNAL && time_travel_ext_request(ns))
+ time_travel_ext_wait(idle);
+ else
+ time_travel_set_time(ns);
+}
+
+static struct time_travel_event *time_travel_first_event(void)
+{
+ return list_first_entry_or_null(&time_travel_events,
+ struct time_travel_event,
+ list);
+}
+
+static void __time_travel_add_event(struct time_travel_event *e,
+ unsigned long long time)
+{
+ struct time_travel_event *tmp;
+ bool inserted = false;
+ unsigned long flags;
+
+ if (e->pending)
+ return;
+
+ e->pending = true;
+ e->time = time;
+
+ local_irq_save(flags);
+ list_for_each_entry(tmp, &time_travel_events, list) {
+ /*
+ * Add the new entry before one with higher time,
+ * or if they're equal and both on stack, because
+ * in that case we need to unwind the stack in the
+ * right order, and the later event (timer sleep
+ * or such) must be dequeued first.
+ */
+ if ((tmp->time > e->time) ||
+ (tmp->time == e->time && tmp->onstack && e->onstack)) {
+ list_add_tail(&e->list, &tmp->list);
+ inserted = true;
+ break;
+ }
+ }
+
+ if (!inserted)
+ list_add_tail(&e->list, &time_travel_events);
+
+ tmp = time_travel_first_event();
+ time_travel_ext_update_request(tmp->time);
+ time_travel_next_event = tmp->time;
+ local_irq_restore(flags);
+}
+
+static void time_travel_add_event(struct time_travel_event *e,
+ unsigned long long time)
+{
+ if (WARN_ON(!e->fn))
+ return;
+
+ __time_travel_add_event(e, time);
+}
+
+void time_travel_add_event_rel(struct time_travel_event *e,
+ unsigned long long delay_ns)
+{
+ time_travel_add_event(e, time_travel_time + delay_ns);
+}
+
+void time_travel_periodic_timer(struct time_travel_event *e)
+{
+ time_travel_add_event(&time_travel_timer_event,
+ time_travel_time + time_travel_timer_interval);
+ deliver_alarm();
+}
+
+void deliver_time_travel_irqs(void)
+{
+ struct time_travel_event *e;
+ unsigned long flags;
+
+ /*
+ * Don't do anything for most cases. Note that because here we have
+ * to disable IRQs (and re-enable later) we'll actually recurse at
+ * the end of the function, so this is strictly necessary.
+ */
+ if (likely(list_empty(&time_travel_irqs)))
+ return;
+
+ local_irq_save(flags);
+ irq_enter();
+ while ((e = list_first_entry_or_null(&time_travel_irqs,
+ struct time_travel_event,
+ list))) {
+ list_del(&e->list);
+ e->pending = false;
+ e->fn(e);
+ }
+ irq_exit();
+ local_irq_restore(flags);
+}
+
+static void time_travel_deliver_event(struct time_travel_event *e)
+{
+ if (e == &time_travel_timer_event) {
+ /*
+ * deliver_alarm() does the irq_enter/irq_exit
+ * by itself, so must handle it specially here
+ */
+ e->fn(e);
+ } else if (irqs_disabled()) {
+ list_add_tail(&e->list, &time_travel_irqs);
+ /*
+ * set pending again, it was set to false when the
+ * event was deleted from the original list, but
+ * now it's still pending until we deliver the IRQ.
+ */
+ e->pending = true;
+ } else {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ irq_enter();
+ e->fn(e);
+ irq_exit();
+ local_irq_restore(flags);
+ }
+}
+
+bool time_travel_del_event(struct time_travel_event *e)
+{
+ unsigned long flags;
+
+ if (!e->pending)
+ return false;
+ local_irq_save(flags);
+ list_del(&e->list);
+ e->pending = false;
+ local_irq_restore(flags);
+ return true;
+}
+
+static void time_travel_update_time(unsigned long long next, bool idle)
+{
+ struct time_travel_event ne = {
+ .onstack = true,
+ };
+ struct time_travel_event *e;
+ bool finished = idle;
+
+ /* add it without a handler - we deal with that specifically below */
+ __time_travel_add_event(&ne, next);
+
+ do {
+ e = time_travel_first_event();
+
+ BUG_ON(!e);
+ __time_travel_update_time(e->time, idle);
+
+ /* new events may have been inserted while we were waiting */
+ if (e == time_travel_first_event()) {
+ BUG_ON(!time_travel_del_event(e));
+ BUG_ON(time_travel_time != e->time);
+
+ if (e == &ne) {
+ finished = true;
+ } else {
+ if (e->onstack)
+ panic("On-stack event dequeued outside of the stack! time=%lld, event time=%lld, event=%pS\n",
+ time_travel_time, e->time, e);
+ time_travel_deliver_event(e);
+ }
+ }
+
+ e = time_travel_first_event();
+ if (e)
+ time_travel_ext_update_request(e->time);
+ } while (ne.pending && !finished);
+
+ time_travel_del_event(&ne);
+}
+
+void time_travel_ndelay(unsigned long nsec)
+{
+ time_travel_update_time(time_travel_time + nsec, false);
+}
+EXPORT_SYMBOL(time_travel_ndelay);
+
+void time_travel_add_irq_event(struct time_travel_event *e)
+{
+ BUG_ON(time_travel_mode != TT_MODE_EXTERNAL);
+
+ time_travel_ext_get_time();
+ /*
+ * We could model interrupt latency here, for now just
+ * don't have any latency at all and request the exact
+ * same time (again) to run the interrupt...
+ */
+ time_travel_add_event(e, time_travel_time);
+}
+EXPORT_SYMBOL_GPL(time_travel_add_irq_event);
+
+static void time_travel_oneshot_timer(struct time_travel_event *e)
+{
+ deliver_alarm();
+}
+
+void time_travel_sleep(void)
+{
+ /*
+ * Wait "forever" (using S64_MAX because there are some potential
+ * wrapping issues, especially with the current TT_MODE_EXTERNAL
+ * controller application.
+ */
+ unsigned long long next = S64_MAX;
+
+ if (time_travel_mode == TT_MODE_BASIC)
+ os_timer_disable();
+
+ time_travel_update_time(next, true);
+
+ if (time_travel_mode == TT_MODE_BASIC &&
+ time_travel_timer_event.pending) {
+ if (time_travel_timer_event.fn == time_travel_periodic_timer) {
+ /*
+ * This is somewhat wrong - we should get the first
+ * one sooner like the os_timer_one_shot() below...
+ */
+ os_timer_set_interval(time_travel_timer_interval);
+ } else {
+ os_timer_one_shot(time_travel_timer_event.time - next);
+ }
+ }
+}
+
+static void time_travel_handle_real_alarm(void)
+{
+ time_travel_set_time(time_travel_next_event);
+
+ time_travel_del_event(&time_travel_timer_event);
+
+ if (time_travel_timer_event.fn == time_travel_periodic_timer)
+ time_travel_add_event(&time_travel_timer_event,
+ time_travel_time +
+ time_travel_timer_interval);
+}
+
+static void time_travel_set_interval(unsigned long long interval)
+{
+ time_travel_timer_interval = interval;
+}
+
+static int time_travel_connect_external(const char *socket)
+{
+ const char *sep;
+ unsigned long long id = (unsigned long long)-1;
+ int rc;
+
+ if ((sep = strchr(socket, ':'))) {
+ char buf[25] = {};
+ if (sep - socket > sizeof(buf) - 1)
+ goto invalid_number;
+
+ memcpy(buf, socket, sep - socket);
+ if (kstrtoull(buf, 0, &id)) {
+invalid_number:
+ panic("time-travel: invalid external ID in string '%s'\n",
+ socket);
+ return -EINVAL;
+ }
+
+ socket = sep + 1;
+ }
+
+ rc = os_connect_socket(socket);
+ if (rc < 0) {
+ panic("time-travel: failed to connect to external socket %s\n",
+ socket);
+ return rc;
+ }
+
+ time_travel_ext_fd = rc;
+
+ time_travel_ext_req(UM_TIMETRAVEL_START, id);
+
+ return 1;
+}
+
+static void time_travel_set_start(void)
+{
+ if (time_travel_start_set)
+ return;
+
+ switch (time_travel_mode) {
+ case TT_MODE_EXTERNAL:
+ time_travel_start = time_travel_ext_req(UM_TIMETRAVEL_GET_TOD, -1);
+ /* controller gave us the *current* time, so adjust by that */
+ time_travel_ext_get_time();
+ time_travel_start -= time_travel_time;
+ break;
+ case TT_MODE_INFCPU:
+ case TT_MODE_BASIC:
+ if (!time_travel_start_set)
+ time_travel_start = os_persistent_clock_emulation();
+ break;
+ case TT_MODE_OFF:
+ /* we just read the host clock with os_persistent_clock_emulation() */
+ break;
+ }
+
+ time_travel_start_set = true;
+}
+#else /* CONFIG_UML_TIME_TRAVEL_SUPPORT */
+#define time_travel_start_set 0
+#define time_travel_start 0
+#define time_travel_time 0
+#define time_travel_ext_waiting 0
+
+static inline void time_travel_update_time(unsigned long long ns, bool retearly)
+{
+}
+
+static inline void time_travel_handle_real_alarm(void)
+{
+}
+
+static void time_travel_set_interval(unsigned long long interval)
+{
+}
+
+static inline void time_travel_set_start(void)
+{
+}
+
+/* fail link if this actually gets used */
+extern u64 time_travel_ext_req(u32 op, u64 time);
+
+/* these are empty macros so the struct/fn need not exist */
+#define time_travel_add_event(e, time) do { } while (0)
+/* externally not usable - redefine here so we can */
+#undef time_travel_del_event
+#define time_travel_del_event(e) do { } while (0)
+#endif
+
+void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
+{
+ unsigned long flags;
+
+ /*
+ * In basic time-travel mode we still get real interrupts
+ * (signals) but since we don't read time from the OS, we
+ * must update the simulated time here to the expiry when
+ * we get a signal.
+ * This is not the case in inf-cpu mode, since there we
+ * never get any real signals from the OS.
+ */
+ if (time_travel_mode == TT_MODE_BASIC)
+ time_travel_handle_real_alarm();
+
+ local_irq_save(flags);
+ do_IRQ(TIMER_IRQ, regs);
+ local_irq_restore(flags);
+}
+
+static int itimer_shutdown(struct clock_event_device *evt)
+{
+ if (time_travel_mode != TT_MODE_OFF)
+ time_travel_del_event(&time_travel_timer_event);
+
+ if (time_travel_mode != TT_MODE_INFCPU &&
+ time_travel_mode != TT_MODE_EXTERNAL)
+ os_timer_disable();
+
+ return 0;
+}
+
+static int itimer_set_periodic(struct clock_event_device *evt)
+{
+ unsigned long long interval = NSEC_PER_SEC / HZ;
+
+ if (time_travel_mode != TT_MODE_OFF) {
+ time_travel_del_event(&time_travel_timer_event);
+ time_travel_set_event_fn(&time_travel_timer_event,
+ time_travel_periodic_timer);
+ time_travel_set_interval(interval);
+ time_travel_add_event(&time_travel_timer_event,
+ time_travel_time + interval);
+ }
+
+ if (time_travel_mode != TT_MODE_INFCPU &&
+ time_travel_mode != TT_MODE_EXTERNAL)
+ os_timer_set_interval(interval);
+
+ return 0;
+}
+
+static int itimer_next_event(unsigned long delta,
+ struct clock_event_device *evt)
+{
+ delta += 1;
+
+ if (time_travel_mode != TT_MODE_OFF) {
+ time_travel_del_event(&time_travel_timer_event);
+ time_travel_set_event_fn(&time_travel_timer_event,
+ time_travel_oneshot_timer);
+ time_travel_add_event(&time_travel_timer_event,
+ time_travel_time + delta);
+ }
+
+ if (time_travel_mode != TT_MODE_INFCPU &&
+ time_travel_mode != TT_MODE_EXTERNAL)
+ return os_timer_one_shot(delta);
+
+ return 0;
+}
+
+static int itimer_one_shot(struct clock_event_device *evt)
+{
+ return itimer_next_event(0, evt);
+}
+
+static struct clock_event_device timer_clockevent = {
+ .name = "posix-timer",
+ .rating = 250,
+ .cpumask = cpu_possible_mask,
+ .features = CLOCK_EVT_FEAT_PERIODIC |
+ CLOCK_EVT_FEAT_ONESHOT,
+ .set_state_shutdown = itimer_shutdown,
+ .set_state_periodic = itimer_set_periodic,
+ .set_state_oneshot = itimer_one_shot,
+ .set_next_event = itimer_next_event,
+ .shift = 0,
+ .max_delta_ns = 0xffffffff,
+ .max_delta_ticks = 0xffffffff,
+ .min_delta_ns = TIMER_MIN_DELTA,
+ .min_delta_ticks = TIMER_MIN_DELTA, // microsecond resolution should be enough for anyone, same as 640K RAM
+ .irq = 0,
+ .mult = 1,
+};
+
+static irqreturn_t um_timer(int irq, void *dev)
+{
+ if (get_current()->mm != NULL)
+ {
+ /* userspace - relay signal, results in correct userspace timers */
+ os_alarm_process(get_current()->mm->context.id.u.pid);
+ }
+
+ (*timer_clockevent.event_handler)(&timer_clockevent);
+
+ return IRQ_HANDLED;
+}
+
+static u64 timer_read(struct clocksource *cs)
+{
+ if (time_travel_mode != TT_MODE_OFF) {
+ /*
+ * We make reading the timer cost a bit so that we don't get
+ * stuck in loops that expect time to move more than the
+ * exact requested sleep amount, e.g. python's socket server,
+ * see https://bugs.python.org/issue37026.
+ *
+ * However, don't do that when we're in interrupt or such as
+ * then we might recurse into our own processing, and get to
+ * even more waiting, and that's not good - it messes up the
+ * "what do I do next" and onstack event we use to know when
+ * to return from time_travel_update_time().
+ */
+ if (!irqs_disabled() && !in_interrupt() && !in_softirq() &&
+ !time_travel_ext_waiting)
+ time_travel_update_time(time_travel_time +
+ TIMER_MULTIPLIER,
+ false);
+ return time_travel_time / TIMER_MULTIPLIER;
+ }
+
+ return os_nsecs() / TIMER_MULTIPLIER;
+}
+
+static struct clocksource timer_clocksource = {
+ .name = "timer",
+ .rating = 300,
+ .read = timer_read,
+ .mask = CLOCKSOURCE_MASK(64),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static void __init um_timer_setup(void)
+{
+ int err;
+
+ err = request_irq(TIMER_IRQ, um_timer, IRQF_TIMER, "hr timer", NULL);
+ if (err != 0)
+ printk(KERN_ERR "register_timer : request_irq failed - "
+ "errno = %d\n", -err);
+
+ err = os_timer_create();
+ if (err != 0) {
+ printk(KERN_ERR "creation of timer failed - errno = %d\n", -err);
+ return;
+ }
+
+ err = clocksource_register_hz(&timer_clocksource, NSEC_PER_SEC/TIMER_MULTIPLIER);
+ if (err) {
+ printk(KERN_ERR "clocksource_register_hz returned %d\n", err);
+ return;
+ }
+ clockevents_register_device(&timer_clockevent);
+}
+
+void read_persistent_clock64(struct timespec64 *ts)
+{
+ long long nsecs;
+
+ time_travel_set_start();
+
+ if (time_travel_mode != TT_MODE_OFF)
+ nsecs = time_travel_start + time_travel_time;
+ else
+ nsecs = os_persistent_clock_emulation();
+
+ set_normalized_timespec64(ts, nsecs / NSEC_PER_SEC,
+ nsecs % NSEC_PER_SEC);
+}
+
+void __init time_init(void)
+{
+ timer_set_signal_handler();
+ late_time_init = um_timer_setup;
+}
+
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+unsigned long calibrate_delay_is_known(void)
+{
+ if (time_travel_mode == TT_MODE_INFCPU ||
+ time_travel_mode == TT_MODE_EXTERNAL)
+ return 1;
+ return 0;
+}
+
+int setup_time_travel(char *str)
+{
+ if (strcmp(str, "=inf-cpu") == 0) {
+ time_travel_mode = TT_MODE_INFCPU;
+ timer_clockevent.name = "time-travel-timer-infcpu";
+ timer_clocksource.name = "time-travel-clock";
+ return 1;
+ }
+
+ if (strncmp(str, "=ext:", 5) == 0) {
+ time_travel_mode = TT_MODE_EXTERNAL;
+ timer_clockevent.name = "time-travel-timer-external";
+ timer_clocksource.name = "time-travel-clock-external";
+ return time_travel_connect_external(str + 5);
+ }
+
+ if (!*str) {
+ time_travel_mode = TT_MODE_BASIC;
+ timer_clockevent.name = "time-travel-timer";
+ timer_clocksource.name = "time-travel-clock";
+ return 1;
+ }
+
+ return -EINVAL;
+}
+
+__setup("time-travel", setup_time_travel);
+__uml_help(setup_time_travel,
+"time-travel\n"
+"This option just enables basic time travel mode, in which the clock/timers\n"
+"inside the UML instance skip forward when there's nothing to do, rather than\n"
+"waiting for real time to elapse. However, instance CPU speed is limited by\n"
+"the real CPU speed, so e.g. a 10ms timer will always fire after ~10ms wall\n"
+"clock (but quicker when there's nothing to do).\n"
+"\n"
+"time-travel=inf-cpu\n"
+"This enables time travel mode with infinite processing power, in which there\n"
+"are no wall clock timers, and any CPU processing happens - as seen from the\n"
+"guest - instantly. This can be useful for accurate simulation regardless of\n"
+"debug overhead, physical CPU speed, etc. but is somewhat dangerous as it can\n"
+"easily lead to getting stuck (e.g. if anything in the system busy loops).\n"
+"\n"
+"time-travel=ext:[ID:]/path/to/socket\n"
+"This enables time travel mode similar to =inf-cpu, except the system will\n"
+"use the given socket to coordinate with a central scheduler, in order to\n"
+"have more than one system simultaneously be on simulated time. The virtio\n"
+"driver code in UML knows about this so you can also simulate networks and\n"
+"devices using it, assuming the device has the right capabilities.\n"
+"The optional ID is a 64-bit integer that's sent to the central scheduler.\n");
+
+int setup_time_travel_start(char *str)
+{
+ int err;
+
+ err = kstrtoull(str, 0, &time_travel_start);
+ if (err)
+ return err;
+
+ time_travel_start_set = 1;
+ return 1;
+}
+
+__setup("time-travel-start", setup_time_travel_start);
+__uml_help(setup_time_travel_start,
+"time-travel-start=<seconds>\n"
+"Configure the UML instance's wall clock to start at this value rather than\n"
+"the host's wall clock at the time of UML boot.\n");
+#endif
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-24 23:18:11 +0000