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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
4 * Copyright (C) 2015 Thomas Meyer ([email protected])
5 * Copyright (C) 2012-2014 Cisco Systems
6 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
7 * Copyright (C) 2019 Intel Corporation
8 */
9
10#include <linux/clockchips.h>
11#include <linux/init.h>
12#include <linux/interrupt.h>
13#include <linux/jiffies.h>
14#include <linux/mm.h>
15#include <linux/sched.h>
16#include <linux/spinlock.h>
17#include <linux/threads.h>
18#include <asm/irq.h>
19#include <asm/param.h>
20#include <kern_util.h>
21#include <os.h>
22#include <linux/delay.h>
23#include <linux/time-internal.h>
24#include <linux/um_timetravel.h>
25#include <shared/init.h>
26
27#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
28#include <linux/sched/clock.h>
29
30enum time_travel_mode time_travel_mode;
31EXPORT_SYMBOL_GPL(time_travel_mode);
32
33static bool time_travel_start_set;
34static unsigned long long time_travel_start;
35static unsigned long long time_travel_time;
36static unsigned long long time_travel_shm_offset;
37static LIST_HEAD(time_travel_events);
38static LIST_HEAD(time_travel_irqs);
39static unsigned long long time_travel_timer_interval;
40static unsigned long long time_travel_next_event;
41static struct time_travel_event time_travel_timer_event;
42static int time_travel_ext_fd = -1;
43static unsigned int time_travel_ext_waiting;
44static bool time_travel_ext_prev_request_valid;
45static unsigned long long time_travel_ext_prev_request;
46static unsigned long long *time_travel_ext_free_until;
47static unsigned long long _time_travel_ext_free_until;
48static u16 time_travel_shm_id;
49static struct um_timetravel_schedshm *time_travel_shm;
50static union um_timetravel_schedshm_client *time_travel_shm_client;
51
52unsigned long tt_extra_sched_jiffies;
53
54notrace unsigned long long sched_clock(void)
55{
56 return (unsigned long long)(jiffies - INITIAL_JIFFIES +
57 tt_extra_sched_jiffies)
58 * (NSEC_PER_SEC / HZ);
59}
60
61static void time_travel_set_time(unsigned long long ns)
62{
63 if (unlikely(ns < time_travel_time))
64 panic("time-travel: time goes backwards %lld -> %lld\n",
65 time_travel_time, ns);
66 else if (unlikely(ns >= S64_MAX))
67 panic("The system was going to sleep forever, aborting");
68
69 time_travel_time = ns;
70}
71
72enum time_travel_message_handling {
73 TTMH_IDLE,
74 TTMH_POLL,
75 TTMH_READ,
76 TTMH_READ_START_ACK,
77};
78
79static u64 bc_message;
80int time_travel_should_print_bc_msg;
81
82void _time_travel_print_bc_msg(void)
83{
84 time_travel_should_print_bc_msg = 0;
85 printk(KERN_INFO "time-travel: received broadcast 0x%llx\n", bc_message);
86}
87
88static void time_travel_setup_shm(int fd, u16 id)
89{
90 u32 len;
91
92 time_travel_shm = os_mmap_rw_shared(fd, sizeof(*time_travel_shm));
93
94 if (!time_travel_shm)
95 goto out;
96
97 len = time_travel_shm->len;
98
99 if (time_travel_shm->version != UM_TIMETRAVEL_SCHEDSHM_VERSION ||
100 len < struct_size(time_travel_shm, clients, id + 1)) {
101 os_unmap_memory(time_travel_shm, sizeof(*time_travel_shm));
102 time_travel_shm = NULL;
103 goto out;
104 }
105
106 time_travel_shm = os_mremap_rw_shared(time_travel_shm,
107 sizeof(*time_travel_shm),
108 len);
109 if (!time_travel_shm)
110 goto out;
111
112 time_travel_shm_offset = time_travel_shm->current_time;
113 time_travel_shm_client = &time_travel_shm->clients[id];
114 time_travel_shm_client->capa |= UM_TIMETRAVEL_SCHEDSHM_CAP_TIME_SHARE;
115 time_travel_shm_id = id;
116 /* always look at that free_until from now on */
117 time_travel_ext_free_until = &time_travel_shm->free_until;
118out:
119 os_close_file(fd);
120}
121
122static void time_travel_handle_message(struct um_timetravel_msg *msg,
123 enum time_travel_message_handling mode)
124{
125 struct um_timetravel_msg resp = {
126 .op = UM_TIMETRAVEL_ACK,
127 };
128 int ret;
129
130 /*
131 * We can't unlock here, but interrupt signals with a timetravel_handler
132 * (see um_request_irq_tt) get to the timetravel_handler anyway.
133 */
134 if (mode != TTMH_READ) {
135 BUG_ON(mode == TTMH_IDLE && !irqs_disabled());
136
137 while (os_poll(1, &time_travel_ext_fd) != 0) {
138 /* nothing */
139 }
140 }
141
142 if (unlikely(mode == TTMH_READ_START_ACK)) {
143 int fd[UM_TIMETRAVEL_SHARED_MAX_FDS];
144
145 ret = os_rcv_fd_msg(time_travel_ext_fd, fd,
146 ARRAY_SIZE(fd), msg, sizeof(*msg));
147 if (ret == sizeof(*msg)) {
148 time_travel_setup_shm(fd[UM_TIMETRAVEL_SHARED_MEMFD],
149 msg->time & UM_TIMETRAVEL_START_ACK_ID);
150 /* we don't use the logging for now */
151 os_close_file(fd[UM_TIMETRAVEL_SHARED_LOGFD]);
152 }
153 } else {
154 ret = os_read_file(time_travel_ext_fd, msg, sizeof(*msg));
155 }
156
157 if (ret == 0)
158 panic("time-travel external link is broken\n");
159 if (ret != sizeof(*msg))
160 panic("invalid time-travel message - %d bytes\n", ret);
161
162 switch (msg->op) {
163 default:
164 WARN_ONCE(1, "time-travel: unexpected message %lld\n",
165 (unsigned long long)msg->op);
166 break;
167 case UM_TIMETRAVEL_ACK:
168 return;
169 case UM_TIMETRAVEL_RUN:
170 time_travel_set_time(msg->time);
171 if (time_travel_shm) {
172 /* no request right now since we're running */
173 time_travel_shm_client->flags &=
174 ~UM_TIMETRAVEL_SCHEDSHM_FLAGS_REQ_RUN;
175 /* no ack for shared memory RUN */
176 return;
177 }
178 break;
179 case UM_TIMETRAVEL_FREE_UNTIL:
180 /* not supposed to get this with shm, but ignore it */
181 if (time_travel_shm)
182 break;
183 time_travel_ext_free_until = &_time_travel_ext_free_until;
184 _time_travel_ext_free_until = msg->time;
185 break;
186 case UM_TIMETRAVEL_BROADCAST:
187 bc_message = msg->time;
188 time_travel_should_print_bc_msg = 1;
189 break;
190 }
191
192 resp.seq = msg->seq;
193 os_write_file(time_travel_ext_fd, &resp, sizeof(resp));
194}
195
196static u64 time_travel_ext_req(u32 op, u64 time)
197{
198 static int seq;
199 int mseq = ++seq;
200 struct um_timetravel_msg msg = {
201 .op = op,
202 .time = time,
203 .seq = mseq,
204 };
205
206 /*
207 * We need to block even the timetravel handlers of SIGIO here and
208 * only restore their use when we got the ACK - otherwise we may
209 * (will) get interrupted by that, try to queue the IRQ for future
210 * processing and thus send another request while we're still waiting
211 * for an ACK, but the peer doesn't know we got interrupted and will
212 * send the ACKs in the same order as the message, but we'd need to
213 * see them in the opposite order ...
214 *
215 * This wouldn't matter *too* much, but some ACKs carry the
216 * current time (for UM_TIMETRAVEL_GET) and getting another
217 * ACK without a time would confuse us a lot!
218 *
219 * The sequence number assignment that happens here lets us
220 * debug such message handling issues more easily.
221 */
222 block_signals_hard();
223 os_write_file(time_travel_ext_fd, &msg, sizeof(msg));
224
225 /* no ACK expected for WAIT in shared memory mode */
226 if (msg.op == UM_TIMETRAVEL_WAIT && time_travel_shm)
227 goto done;
228
229 while (msg.op != UM_TIMETRAVEL_ACK)
230 time_travel_handle_message(&msg,
231 op == UM_TIMETRAVEL_START ?
232 TTMH_READ_START_ACK :
233 TTMH_READ);
234
235 if (msg.seq != mseq)
236 panic("time-travel: ACK message has different seqno! op=%d, seq=%d != %d time=%lld\n",
237 msg.op, msg.seq, mseq, msg.time);
238
239 if (op == UM_TIMETRAVEL_GET)
240 time_travel_set_time(msg.time);
241done:
242 unblock_signals_hard();
243
244 return msg.time;
245}
246
247void __time_travel_wait_readable(int fd)
248{
249 int fds[2] = { fd, time_travel_ext_fd };
250 int ret;
251
252 if (time_travel_mode != TT_MODE_EXTERNAL)
253 return;
254
255 while ((ret = os_poll(2, fds))) {
256 struct um_timetravel_msg msg;
257
258 if (ret == 1)
259 time_travel_handle_message(&msg, TTMH_READ);
260 }
261}
262EXPORT_SYMBOL_GPL(__time_travel_wait_readable);
263
264static void time_travel_ext_update_request(unsigned long long time)
265{
266 if (time_travel_mode != TT_MODE_EXTERNAL)
267 return;
268
269 /* asked for exactly this time previously */
270 if (time_travel_ext_prev_request_valid &&
271 time == time_travel_ext_prev_request)
272 return;
273
274 /*
275 * if we're running and are allowed to run past the request
276 * then we don't need to update it either
277 *
278 * Note for shm we ignore FREE_UNTIL messages and leave the pointer
279 * to shared memory, and for non-shm the offset is 0.
280 */
281 if (!time_travel_ext_waiting && time_travel_ext_free_until &&
282 time < (*time_travel_ext_free_until - time_travel_shm_offset))
283 return;
284
285 time_travel_ext_prev_request = time;
286 time_travel_ext_prev_request_valid = true;
287
288 if (time_travel_shm) {
289 union um_timetravel_schedshm_client *running;
290
291 running = &time_travel_shm->clients[time_travel_shm->running_id];
292
293 if (running->capa & UM_TIMETRAVEL_SCHEDSHM_CAP_TIME_SHARE) {
294 time_travel_shm_client->flags |=
295 UM_TIMETRAVEL_SCHEDSHM_FLAGS_REQ_RUN;
296 time += time_travel_shm_offset;
297 time_travel_shm_client->req_time = time;
298 if (time < time_travel_shm->free_until)
299 time_travel_shm->free_until = time;
300 return;
301 }
302 }
303
304 time_travel_ext_req(UM_TIMETRAVEL_REQUEST, time);
305}
306
307void __time_travel_propagate_time(void)
308{
309 static unsigned long long last_propagated;
310
311 if (time_travel_shm) {
312 if (time_travel_shm->running_id != time_travel_shm_id)
313 panic("time-travel: setting time while not running\n");
314 time_travel_shm->current_time = time_travel_time +
315 time_travel_shm_offset;
316 return;
317 }
318
319 if (last_propagated == time_travel_time)
320 return;
321
322 time_travel_ext_req(UM_TIMETRAVEL_UPDATE, time_travel_time);
323 last_propagated = time_travel_time;
324}
325EXPORT_SYMBOL_GPL(__time_travel_propagate_time);
326
327/* returns true if we must do a wait to the simtime device */
328static bool time_travel_ext_request(unsigned long long time)
329{
330 /*
331 * If we received an external sync point ("free until") then we
332 * don't have to request/wait for anything until then, unless
333 * we're already waiting.
334 *
335 * Note for shm we ignore FREE_UNTIL messages and leave the pointer
336 * to shared memory, and for non-shm the offset is 0.
337 */
338 if (!time_travel_ext_waiting && time_travel_ext_free_until &&
339 time < (*time_travel_ext_free_until - time_travel_shm_offset))
340 return false;
341
342 time_travel_ext_update_request(time);
343 return true;
344}
345
346static void time_travel_ext_wait(bool idle)
347{
348 struct um_timetravel_msg msg = {
349 .op = UM_TIMETRAVEL_ACK,
350 };
351
352 time_travel_ext_prev_request_valid = false;
353 if (!time_travel_shm)
354 time_travel_ext_free_until = NULL;
355 time_travel_ext_waiting++;
356
357 time_travel_ext_req(UM_TIMETRAVEL_WAIT, -1);
358
359 /*
360 * Here we are deep in the idle loop, so we have to break out of the
361 * kernel abstraction in a sense and implement this in terms of the
362 * UML system waiting on the VQ interrupt while sleeping, when we get
363 * the signal it'll call time_travel_ext_vq_notify_done() completing the
364 * call.
365 */
366 while (msg.op != UM_TIMETRAVEL_RUN)
367 time_travel_handle_message(&msg, idle ? TTMH_IDLE : TTMH_POLL);
368
369 time_travel_ext_waiting--;
370
371 /* we might request more stuff while polling - reset when we run */
372 time_travel_ext_prev_request_valid = false;
373}
374
375static void time_travel_ext_get_time(void)
376{
377 if (time_travel_shm)
378 time_travel_set_time(time_travel_shm->current_time -
379 time_travel_shm_offset);
380 else
381 time_travel_ext_req(UM_TIMETRAVEL_GET, -1);
382}
383
384static void __time_travel_update_time(unsigned long long ns, bool idle)
385{
386 if (time_travel_mode == TT_MODE_EXTERNAL && time_travel_ext_request(ns))
387 time_travel_ext_wait(idle);
388 else
389 time_travel_set_time(ns);
390}
391
392static struct time_travel_event *time_travel_first_event(void)
393{
394 return list_first_entry_or_null(&time_travel_events,
395 struct time_travel_event,
396 list);
397}
398
399static void __time_travel_add_event(struct time_travel_event *e,
400 unsigned long long time)
401{
402 struct time_travel_event *tmp;
403 bool inserted = false;
404 unsigned long flags;
405
406 if (e->pending)
407 return;
408
409 e->pending = true;
410 e->time = time;
411
412 local_irq_save(flags);
413 list_for_each_entry(tmp, &time_travel_events, list) {
414 /*
415 * Add the new entry before one with higher time,
416 * or if they're equal and both on stack, because
417 * in that case we need to unwind the stack in the
418 * right order, and the later event (timer sleep
419 * or such) must be dequeued first.
420 */
421 if ((tmp->time > e->time) ||
422 (tmp->time == e->time && tmp->onstack && e->onstack)) {
423 list_add_tail(&e->list, &tmp->list);
424 inserted = true;
425 break;
426 }
427 }
428
429 if (!inserted)
430 list_add_tail(&e->list, &time_travel_events);
431
432 tmp = time_travel_first_event();
433 time_travel_ext_update_request(tmp->time);
434 time_travel_next_event = tmp->time;
435 local_irq_restore(flags);
436}
437
438static void time_travel_add_event(struct time_travel_event *e,
439 unsigned long long time)
440{
441 if (WARN_ON(!e->fn))
442 return;
443
444 __time_travel_add_event(e, time);
445}
446
447void time_travel_add_event_rel(struct time_travel_event *e,
448 unsigned long long delay_ns)
449{
450 time_travel_add_event(e, time_travel_time + delay_ns);
451}
452
453static void time_travel_periodic_timer(struct time_travel_event *e)
454{
455 time_travel_add_event(&time_travel_timer_event,
456 time_travel_time + time_travel_timer_interval);
457
458 /* clock tick; decrease extra jiffies by keeping sched_clock constant */
459 if (tt_extra_sched_jiffies > 0)
460 tt_extra_sched_jiffies -= 1;
461
462 deliver_alarm();
463}
464
465void deliver_time_travel_irqs(void)
466{
467 struct time_travel_event *e;
468 unsigned long flags;
469
470 /*
471 * Don't do anything for most cases. Note that because here we have
472 * to disable IRQs (and re-enable later) we'll actually recurse at
473 * the end of the function, so this is strictly necessary.
474 */
475 if (likely(list_empty(&time_travel_irqs)))
476 return;
477
478 local_irq_save(flags);
479 irq_enter();
480 while ((e = list_first_entry_or_null(&time_travel_irqs,
481 struct time_travel_event,
482 list))) {
483 list_del(&e->list);
484 e->pending = false;
485 e->fn(e);
486 }
487 irq_exit();
488 local_irq_restore(flags);
489}
490
491static void time_travel_deliver_event(struct time_travel_event *e)
492{
493 if (e == &time_travel_timer_event) {
494 /*
495 * deliver_alarm() does the irq_enter/irq_exit
496 * by itself, so must handle it specially here
497 */
498 e->fn(e);
499 } else if (irqs_disabled()) {
500 list_add_tail(&e->list, &time_travel_irqs);
501 /*
502 * set pending again, it was set to false when the
503 * event was deleted from the original list, but
504 * now it's still pending until we deliver the IRQ.
505 */
506 e->pending = true;
507 } else {
508 unsigned long flags;
509
510 local_irq_save(flags);
511 irq_enter();
512 e->fn(e);
513 irq_exit();
514 local_irq_restore(flags);
515 }
516}
517
518bool time_travel_del_event(struct time_travel_event *e)
519{
520 unsigned long flags;
521
522 if (!e->pending)
523 return false;
524 local_irq_save(flags);
525 list_del(&e->list);
526 e->pending = false;
527 local_irq_restore(flags);
528 return true;
529}
530
531static void time_travel_update_time(unsigned long long next, bool idle)
532{
533 struct time_travel_event ne = {
534 .onstack = true,
535 };
536 struct time_travel_event *e;
537 bool finished = idle;
538
539 /* add it without a handler - we deal with that specifically below */
540 __time_travel_add_event(&ne, next);
541
542 do {
543 e = time_travel_first_event();
544
545 BUG_ON(!e);
546 __time_travel_update_time(e->time, idle);
547
548 /* new events may have been inserted while we were waiting */
549 if (e == time_travel_first_event()) {
550 BUG_ON(!time_travel_del_event(e));
551 BUG_ON(time_travel_time != e->time);
552
553 if (e == &ne) {
554 finished = true;
555 } else {
556 if (e->onstack)
557 panic("On-stack event dequeued outside of the stack! time=%lld, event time=%lld, event=%pS\n",
558 time_travel_time, e->time, e);
559 time_travel_deliver_event(e);
560 }
561 }
562
563 e = time_travel_first_event();
564 if (e)
565 time_travel_ext_update_request(e->time);
566 } while (ne.pending && !finished);
567
568 time_travel_del_event(&ne);
569}
570
571static void time_travel_update_time_rel(unsigned long long offs)
572{
573 unsigned long flags;
574
575 /*
576 * Disable interrupts before calculating the new time so
577 * that a real timer interrupt (signal) can't happen at
578 * a bad time e.g. after we read time_travel_time but
579 * before we've completed updating the time.
580 */
581 local_irq_save(flags);
582 time_travel_update_time(time_travel_time + offs, false);
583 local_irq_restore(flags);
584}
585
586void time_travel_ndelay(unsigned long nsec)
587{
588 /*
589 * Not strictly needed to use _rel() version since this is
590 * only used in INFCPU/EXT modes, but it doesn't hurt and
591 * is more readable too.
592 */
593 time_travel_update_time_rel(nsec);
594}
595EXPORT_SYMBOL(time_travel_ndelay);
596
597void time_travel_add_irq_event(struct time_travel_event *e)
598{
599 BUG_ON(time_travel_mode != TT_MODE_EXTERNAL);
600
601 time_travel_ext_get_time();
602 /*
603 * We could model interrupt latency here, for now just
604 * don't have any latency at all and request the exact
605 * same time (again) to run the interrupt...
606 */
607 time_travel_add_event(e, time_travel_time);
608}
609EXPORT_SYMBOL_GPL(time_travel_add_irq_event);
610
611static void time_travel_oneshot_timer(struct time_travel_event *e)
612{
613 /* clock tick; decrease extra jiffies by keeping sched_clock constant */
614 if (tt_extra_sched_jiffies > 0)
615 tt_extra_sched_jiffies -= 1;
616
617 deliver_alarm();
618}
619
620void time_travel_sleep(void)
621{
622 /*
623 * Wait "forever" (using S64_MAX because there are some potential
624 * wrapping issues, especially with the current TT_MODE_EXTERNAL
625 * controller application.
626 */
627 unsigned long long next = S64_MAX;
628 int cpu = raw_smp_processor_id();
629
630 if (time_travel_mode == TT_MODE_BASIC)
631 os_timer_disable(cpu);
632
633 time_travel_update_time(next, true);
634
635 if (time_travel_mode == TT_MODE_BASIC &&
636 time_travel_timer_event.pending) {
637 if (time_travel_timer_event.fn == time_travel_periodic_timer) {
638 /*
639 * This is somewhat wrong - we should get the first
640 * one sooner like the os_timer_one_shot() below...
641 */
642 os_timer_set_interval(cpu, time_travel_timer_interval);
643 } else {
644 os_timer_one_shot(cpu, time_travel_timer_event.time - next);
645 }
646 }
647}
648
649static void time_travel_handle_real_alarm(void)
650{
651 time_travel_set_time(time_travel_next_event);
652
653 time_travel_del_event(&time_travel_timer_event);
654
655 if (time_travel_timer_event.fn == time_travel_periodic_timer)
656 time_travel_add_event(&time_travel_timer_event,
657 time_travel_time +
658 time_travel_timer_interval);
659}
660
661static void time_travel_set_interval(unsigned long long interval)
662{
663 time_travel_timer_interval = interval;
664}
665
666static int time_travel_connect_external(const char *socket)
667{
668 const char *sep;
669 unsigned long long id = (unsigned long long)-1;
670 int rc;
671
672 if ((sep = strchr(socket, ':'))) {
673 char buf[25] = {};
674 if (sep - socket > sizeof(buf) - 1)
675 goto invalid_number;
676
677 memcpy(buf, socket, sep - socket);
678 if (kstrtoull(buf, 0, &id)) {
679invalid_number:
680 panic("time-travel: invalid external ID in string '%s'\n",
681 socket);
682 return -EINVAL;
683 }
684
685 socket = sep + 1;
686 }
687
688 rc = os_connect_socket(socket);
689 if (rc < 0) {
690 panic("time-travel: failed to connect to external socket %s\n",
691 socket);
692 return rc;
693 }
694
695 time_travel_ext_fd = rc;
696
697 time_travel_ext_req(UM_TIMETRAVEL_START, id);
698
699 return 1;
700}
701
702static void time_travel_set_start(void)
703{
704 if (time_travel_start_set)
705 return;
706
707 switch (time_travel_mode) {
708 case TT_MODE_EXTERNAL:
709 time_travel_start = time_travel_ext_req(UM_TIMETRAVEL_GET_TOD, -1);
710 /* controller gave us the *current* time, so adjust by that */
711 time_travel_ext_get_time();
712 time_travel_start -= time_travel_time;
713 break;
714 case TT_MODE_INFCPU:
715 case TT_MODE_BASIC:
716 if (!time_travel_start_set)
717 time_travel_start = os_persistent_clock_emulation();
718 break;
719 case TT_MODE_OFF:
720 /* we just read the host clock with os_persistent_clock_emulation() */
721 break;
722 }
723
724 time_travel_start_set = true;
725}
726#else /* CONFIG_UML_TIME_TRAVEL_SUPPORT */
727#define time_travel_start_set 0
728#define time_travel_start 0
729#define time_travel_time 0
730#define time_travel_ext_waiting 0
731
732static inline void time_travel_update_time(unsigned long long ns, bool idle)
733{
734}
735
736static inline void time_travel_update_time_rel(unsigned long long offs)
737{
738}
739
740static inline void time_travel_handle_real_alarm(void)
741{
742}
743
744static void time_travel_set_interval(unsigned long long interval)
745{
746}
747
748static inline void time_travel_set_start(void)
749{
750}
751
752/* fail link if this actually gets used */
753extern u64 time_travel_ext_req(u32 op, u64 time);
754
755/* these are empty macros so the struct/fn need not exist */
756#define time_travel_add_event(e, time) do { } while (0)
757/* externally not usable - redefine here so we can */
758#undef time_travel_del_event
759#define time_travel_del_event(e) do { } while (0)
760#endif
761
762static struct clock_event_device timer_clockevent[NR_CPUS];
763
764void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
765{
766 unsigned long flags;
767
768 /*
769 * In basic time-travel mode we still get real interrupts
770 * (signals) but since we don't read time from the OS, we
771 * must update the simulated time here to the expiry when
772 * we get a signal.
773 * This is not the case in inf-cpu mode, since there we
774 * never get any real signals from the OS.
775 */
776 if (time_travel_mode == TT_MODE_BASIC)
777 time_travel_handle_real_alarm();
778
779 local_irq_save(flags);
780 do_IRQ(TIMER_IRQ, regs);
781 local_irq_restore(flags);
782}
783
784static int itimer_shutdown(struct clock_event_device *evt)
785{
786 int cpu = evt - &timer_clockevent[0];
787
788 if (time_travel_mode != TT_MODE_OFF)
789 time_travel_del_event(&time_travel_timer_event);
790
791 if (time_travel_mode != TT_MODE_INFCPU &&
792 time_travel_mode != TT_MODE_EXTERNAL)
793 os_timer_disable(cpu);
794
795 return 0;
796}
797
798static int itimer_set_periodic(struct clock_event_device *evt)
799{
800 unsigned long long interval = NSEC_PER_SEC / HZ;
801 int cpu = evt - &timer_clockevent[0];
802
803 if (time_travel_mode != TT_MODE_OFF) {
804 time_travel_del_event(&time_travel_timer_event);
805 time_travel_set_event_fn(&time_travel_timer_event,
806 time_travel_periodic_timer);
807 time_travel_set_interval(interval);
808 time_travel_add_event(&time_travel_timer_event,
809 time_travel_time + interval);
810 }
811
812 if (time_travel_mode != TT_MODE_INFCPU &&
813 time_travel_mode != TT_MODE_EXTERNAL)
814 os_timer_set_interval(cpu, interval);
815
816 return 0;
817}
818
819static int itimer_next_event(unsigned long delta,
820 struct clock_event_device *evt)
821{
822 delta += 1;
823
824 if (time_travel_mode != TT_MODE_OFF) {
825 time_travel_del_event(&time_travel_timer_event);
826 time_travel_set_event_fn(&time_travel_timer_event,
827 time_travel_oneshot_timer);
828 time_travel_add_event(&time_travel_timer_event,
829 time_travel_time + delta);
830 }
831
832 if (time_travel_mode != TT_MODE_INFCPU &&
833 time_travel_mode != TT_MODE_EXTERNAL)
834 return os_timer_one_shot(raw_smp_processor_id(), delta);
835
836 return 0;
837}
838
839static int itimer_one_shot(struct clock_event_device *evt)
840{
841 return itimer_next_event(0, evt);
842}
843
844static struct clock_event_device _timer_clockevent = {
845 .name = "posix-timer",
846 .rating = 250,
847 .features = CLOCK_EVT_FEAT_PERIODIC |
848 CLOCK_EVT_FEAT_ONESHOT,
849 .set_state_shutdown = itimer_shutdown,
850 .set_state_periodic = itimer_set_periodic,
851 .set_state_oneshot = itimer_one_shot,
852 .set_next_event = itimer_next_event,
853 .shift = 0,
854 .max_delta_ns = 0xffffffff,
855 .max_delta_ticks = 0xffffffff,
856 .min_delta_ns = TIMER_MIN_DELTA,
857 .min_delta_ticks = TIMER_MIN_DELTA, // microsecond resolution should be enough for anyone, same as 640K RAM
858 .irq = 0,
859 .mult = 1,
860};
861
862static irqreturn_t um_timer(int irq, void *dev)
863{
864 int cpu = raw_smp_processor_id();
865 struct clock_event_device *evt = &timer_clockevent[cpu];
866
867 /*
868 * Interrupt the (possibly) running userspace process, technically this
869 * should only happen if userspace is currently executing.
870 * With infinite CPU time-travel, we can only get here when userspace
871 * is not executing. Do not notify there and avoid spurious scheduling.
872 */
873 if (time_travel_mode != TT_MODE_INFCPU &&
874 time_travel_mode != TT_MODE_EXTERNAL &&
875 get_current()->mm)
876 os_alarm_process(get_current()->mm->context.id.pid);
877
878 evt->event_handler(evt);
879
880 return IRQ_HANDLED;
881}
882
883static u64 timer_read(struct clocksource *cs)
884{
885 if (time_travel_mode != TT_MODE_OFF) {
886 /*
887 * We make reading the timer cost a bit so that we don't get
888 * stuck in loops that expect time to move more than the
889 * exact requested sleep amount, e.g. python's socket server,
890 * see https://bugs.python.org/issue37026.
891 *
892 * However, don't do that when we're in interrupt or such as
893 * then we might recurse into our own processing, and get to
894 * even more waiting, and that's not good - it messes up the
895 * "what do I do next" and onstack event we use to know when
896 * to return from time_travel_update_time().
897 */
898 if (!irqs_disabled() && !in_interrupt() && !in_softirq() &&
899 !time_travel_ext_waiting)
900 time_travel_update_time_rel(TIMER_MULTIPLIER);
901 return time_travel_time / TIMER_MULTIPLIER;
902 }
903
904 return os_nsecs() / TIMER_MULTIPLIER;
905}
906
907static struct clocksource timer_clocksource = {
908 .name = "timer",
909 .rating = 300,
910 .read = timer_read,
911 .mask = CLOCKSOURCE_MASK(64),
912 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
913};
914
915int um_setup_timer(void)
916{
917 int cpu = raw_smp_processor_id();
918 struct clock_event_device *evt = &timer_clockevent[cpu];
919 int err;
920
921 err = os_timer_create();
922 if (err)
923 return err;
924
925 memcpy(evt, &_timer_clockevent, sizeof(*evt));
926 evt->cpumask = cpumask_of(cpu);
927 clockevents_register_device(evt);
928
929 return 0;
930}
931
932static void __init um_timer_init(void)
933{
934 int err;
935
936 err = request_irq(TIMER_IRQ, um_timer, IRQF_TIMER, "hr timer", NULL);
937 if (err != 0)
938 printk(KERN_ERR "register_timer : request_irq failed - "
939 "errno = %d\n", -err);
940
941 err = um_setup_timer();
942 if (err) {
943 printk(KERN_ERR "creation of timer failed - errno = %d\n", -err);
944 return;
945 }
946
947 err = clocksource_register_hz(&timer_clocksource, NSEC_PER_SEC/TIMER_MULTIPLIER);
948 if (err) {
949 printk(KERN_ERR "clocksource_register_hz returned %d\n", err);
950 return;
951 }
952}
953
954void read_persistent_clock64(struct timespec64 *ts)
955{
956 long long nsecs;
957
958 time_travel_set_start();
959
960 if (time_travel_mode != TT_MODE_OFF)
961 nsecs = time_travel_start + time_travel_time;
962 else
963 nsecs = os_persistent_clock_emulation();
964
965 set_normalized_timespec64(ts, nsecs / NSEC_PER_SEC,
966 nsecs % NSEC_PER_SEC);
967}
968
969void __init time_init(void)
970{
971 timer_set_signal_handler();
972 late_time_init = um_timer_init;
973}
974
975#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
976unsigned long calibrate_delay_is_known(void)
977{
978 if (time_travel_mode == TT_MODE_INFCPU ||
979 time_travel_mode == TT_MODE_EXTERNAL)
980 return 1;
981 return 0;
982}
983
984static int setup_time_travel(char *str)
985{
986 if (strcmp(str, "=inf-cpu") == 0) {
987 time_travel_mode = TT_MODE_INFCPU;
988 _timer_clockevent.name = "time-travel-timer-infcpu";
989 timer_clocksource.name = "time-travel-clock";
990 return 1;
991 }
992
993 if (strncmp(str, "=ext:", 5) == 0) {
994 time_travel_mode = TT_MODE_EXTERNAL;
995 _timer_clockevent.name = "time-travel-timer-external";
996 timer_clocksource.name = "time-travel-clock-external";
997 return time_travel_connect_external(str + 5);
998 }
999
1000 if (!*str) {
1001 time_travel_mode = TT_MODE_BASIC;
1002 _timer_clockevent.name = "time-travel-timer";
1003 timer_clocksource.name = "time-travel-clock";
1004 return 1;
1005 }
1006
1007 return -EINVAL;
1008}
1009
1010__setup("time-travel", setup_time_travel);
1011__uml_help(setup_time_travel,
1012"time-travel\n"
1013" This option just enables basic time travel mode, in which the clock/timers\n"
1014" inside the UML instance skip forward when there's nothing to do, rather than\n"
1015" waiting for real time to elapse. However, instance CPU speed is limited by\n"
1016" the real CPU speed, so e.g. a 10ms timer will always fire after ~10ms wall\n"
1017" clock (but quicker when there's nothing to do).\n"
1018"\n"
1019"time-travel=inf-cpu\n"
1020" This enables time travel mode with infinite processing power, in which there\n"
1021" are no wall clock timers, and any CPU processing happens - as seen from the\n"
1022" guest - instantly. This can be useful for accurate simulation regardless of\n"
1023" debug overhead, physical CPU speed, etc. but is somewhat dangerous as it can\n"
1024" easily lead to getting stuck (e.g. if anything in the system busy loops).\n"
1025"\n"
1026"time-travel=ext:[ID:]/path/to/socket\n"
1027" This enables time travel mode similar to =inf-cpu, except the system will\n"
1028" use the given socket to coordinate with a central scheduler, in order to\n"
1029" have more than one system simultaneously be on simulated time. The virtio\n"
1030" driver code in UML knows about this so you can also simulate networks and\n"
1031" devices using it, assuming the device has the right capabilities.\n"
1032" The optional ID is a 64-bit integer that's sent to the central scheduler.\n\n");
1033
1034static int setup_time_travel_start(char *str)
1035{
1036 int err;
1037
1038 err = kstrtoull(str, 0, &time_travel_start);
1039 if (err)
1040 return err;
1041
1042 time_travel_start_set = 1;
1043 return 1;
1044}
1045
1046__setup("time-travel-start=", setup_time_travel_start);
1047__uml_help(setup_time_travel_start,
1048"time-travel-start=<nanoseconds>\n"
1049" Configure the UML instance's wall clock to start at this value rather than\n"
1050" the host's wall clock at the time of UML boot.\n\n");
1051
1052static struct kobject *bc_time_kobject;
1053
1054static ssize_t bc_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
1055{
1056 return sprintf(buf, "0x%llx", bc_message);
1057}
1058
1059static ssize_t bc_store(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count)
1060{
1061 int ret;
1062 u64 user_bc_message;
1063
1064 ret = kstrtou64(buf, 0, &user_bc_message);
1065 if (ret)
1066 return ret;
1067
1068 bc_message = user_bc_message;
1069
1070 time_travel_ext_req(UM_TIMETRAVEL_BROADCAST, bc_message);
1071 pr_info("um: time: sent broadcast message: 0x%llx\n", bc_message);
1072 return count;
1073}
1074
1075static struct kobj_attribute bc_attribute = __ATTR(bc-message, 0660, bc_show, bc_store);
1076
1077static int __init um_bc_start(void)
1078{
1079 if (time_travel_mode != TT_MODE_EXTERNAL)
1080 return 0;
1081
1082 bc_time_kobject = kobject_create_and_add("um-ext-time", kernel_kobj);
1083 if (!bc_time_kobject)
1084 return 0;
1085
1086 if (sysfs_create_file(bc_time_kobject, &bc_attribute.attr))
1087 pr_debug("failed to create the bc file in /sys/kernel/um_time");
1088
1089 return 0;
1090}
1091late_initcall(um_bc_start);
1092#endif