1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 *
26 * Copyright 2012 Nexenta Systems, Inc. All rights reserved.
27 * Copyright (c) 2014, 2016 by Delphix. All rights reserved.
28 */
29
30 #include <sys/types.h>
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/disp.h>
34 #include <sys/var.h>
35 #include <sys/cmn_err.h>
36 #include <sys/debug.h>
37 #include <sys/x86_archext.h>
38 #include <sys/archsystm.h>
39 #include <sys/cpuvar.h>
40 #include <sys/psm_defs.h>
41 #include <sys/clock.h>
42 #include <sys/atomic.h>
43 #include <sys/lockstat.h>
44 #include <sys/smp_impldefs.h>
45 #include <sys/dtrace.h>
46 #include <sys/time.h>
47 #include <sys/panic.h>
48 #include <sys/cpu.h>
49 #include <sys/sdt.h>
50
51 /*
52 * Using the Pentium's TSC register for gethrtime()
53 * ------------------------------------------------
54 *
55 * The Pentium family, like many chip architectures, has a high-resolution
56 * timestamp counter ("TSC") which increments once per CPU cycle. The contents
57 * of the timestamp counter are read with the RDTSC instruction.
58 *
59 * As with its UltraSPARC equivalent (the %tick register), TSC's cycle count
60 * must be translated into nanoseconds in order to implement gethrtime().
61 * We avoid inducing floating point operations in this conversion by
62 * implementing the same nsec_scale algorithm as that found in the sun4u
63 * platform code. The sun4u NATIVE_TIME_TO_NSEC_SCALE block comment contains
64 * a detailed description of the algorithm; the comment is not reproduced
65 * here. This implementation differs only in its value for NSEC_SHIFT:
66 * we implement an NSEC_SHIFT of 5 (instead of sun4u's 4) to allow for
67 * 60 MHz Pentiums.
68 *
69 * While TSC and %tick are both cycle counting registers, TSC's functionality
70 * falls short in several critical ways:
71 *
72 * (a) TSCs on different CPUs are not guaranteed to be in sync. While in
73 * practice they often _are_ in sync, this isn't guaranteed by the
74 * architecture.
75 *
76 * (b) The TSC cannot be reliably set to an arbitrary value. The architecture
77 * only supports writing the low 32-bits of TSC, making it impractical
78 * to rewrite.
79 *
80 * (c) The architecture doesn't have the capacity to interrupt based on
81 * arbitrary values of TSC; there is no TICK_CMPR equivalent.
82 *
83 * Together, (a) and (b) imply that software must track the skew between
84 * TSCs and account for it (it is assumed that while there may exist skew,
85 * there does not exist drift). To determine the skew between CPUs, we
86 * have newly onlined CPUs call tsc_sync_slave(), while the CPU performing
87 * the online operation calls tsc_sync_master().
88 *
89 * In the absence of time-of-day clock adjustments, gethrtime() must stay in
90 * sync with gettimeofday(). This is problematic; given (c), the software
91 * cannot drive its time-of-day source from TSC, and yet they must somehow be
92 * kept in sync. We implement this by having a routine, tsc_tick(), which
93 * is called once per second from the interrupt which drives time-of-day.
94 *
95 * Note that the hrtime base for gethrtime, tsc_hrtime_base, is modified
96 * atomically with nsec_scale under CLOCK_LOCK. This assures that time
97 * monotonically increases.
98 */
99
100 #define NSEC_SHIFT 5
101
102 static uint_t nsec_scale;
103 static uint_t nsec_unscale;
104
105 /*
106 * These two variables used to be grouped together inside of a structure that
107 * lived on a single cache line. A regression (bug ID 4623398) caused the
108 * compiler to emit code that "optimized" away the while-loops below. The
109 * result was that no synchronization between the onlining and onlined CPUs
110 * took place.
111 */
112 static volatile int tsc_ready;
113 static volatile int tsc_sync_go;
114
115 /*
116 * Used as indices into the tsc_sync_snaps[] array.
117 */
118 #define TSC_MASTER 0
119 #define TSC_SLAVE 1
120
121 /*
122 * Used in the tsc_master_sync()/tsc_slave_sync() rendezvous.
123 */
124 #define TSC_SYNC_STOP 1
125 #define TSC_SYNC_GO 2
126 #define TSC_SYNC_DONE 3
127 #define SYNC_ITERATIONS 10
128
129 #define TSC_CONVERT_AND_ADD(tsc, hrt, scale) { \
130 unsigned int *_l = (unsigned int *)&(tsc); \
131 (hrt) += mul32(_l[1], scale) << NSEC_SHIFT; \
132 (hrt) += mul32(_l[0], scale) >> (32 - NSEC_SHIFT); \
133 }
134
135 #define TSC_CONVERT(tsc, hrt, scale) { \
136 unsigned int *_l = (unsigned int *)&(tsc); \
137 (hrt) = mul32(_l[1], scale) << NSEC_SHIFT; \
138 (hrt) += mul32(_l[0], scale) >> (32 - NSEC_SHIFT); \
139 }
140
141 int tsc_master_slave_sync_needed = 1;
142
143 static int tsc_max_delta;
144 static hrtime_t tsc_sync_tick_delta[NCPU];
145 typedef struct tsc_sync {
146 volatile hrtime_t master_tsc, slave_tsc;
147 } tsc_sync_t;
148 static tsc_sync_t *tscp;
149 static hrtime_t largest_tsc_delta = 0;
150 static ulong_t shortest_write_time = ~0UL;
151
152 static hrtime_t tsc_last = 0;
153 static hrtime_t tsc_last_jumped = 0;
154 static hrtime_t tsc_hrtime_base = 0;
155 static int tsc_jumped = 0;
156 static uint32_t tsc_wayback = 0;
157 /*
158 * The cap of 1 second was chosen since it is the frequency at which the
159 * tsc_tick() function runs which means that when gethrtime() is called it
160 * should never be more than 1 second since tsc_last was updated.
161 */
162 static hrtime_t tsc_resume_cap;
163 static hrtime_t tsc_resume_cap_ns = NANOSEC; /* 1s */
164
165 static hrtime_t shadow_tsc_hrtime_base;
166 static hrtime_t shadow_tsc_last;
167 static uint_t shadow_nsec_scale;
168 static uint32_t shadow_hres_lock;
169 int get_tsc_ready();
170
171 static inline
172 hrtime_t tsc_protect(hrtime_t a) {
173 if (a > tsc_resume_cap) {
174 atomic_inc_32(&tsc_wayback);
175 DTRACE_PROBE3(tsc__wayback, htrime_t, a, hrtime_t, tsc_last,
176 uint32_t, tsc_wayback);
177 return (tsc_resume_cap);
178 }
179 return (a);
180 }
181
182 hrtime_t
183 tsc_gethrtime(void)
184 {
185 uint32_t old_hres_lock;
186 hrtime_t tsc, hrt;
187
188 do {
189 old_hres_lock = hres_lock;
190
191 if ((tsc = tsc_read()) >= tsc_last) {
192 /*
193 * It would seem to be obvious that this is true
194 * (that is, the past is less than the present),
195 * but it isn't true in the presence of suspend/resume
196 * cycles. If we manage to call gethrtime()
197 * after a resume, but before the first call to
198 * tsc_tick(), we will see the jump. In this case,
199 * we will simply use the value in TSC as the delta.
200 */
201 tsc -= tsc_last;
202 } else if (tsc >= tsc_last - 2*tsc_max_delta) {
203 /*
204 * There is a chance that tsc_tick() has just run on
205 * another CPU, and we have drifted just enough so that
206 * we appear behind tsc_last. In this case, force the
207 * delta to be zero.
208 */
209 tsc = 0;
210 } else {
211 /*
212 * If we reach this else clause we assume that we have
213 * gone through a suspend/resume cycle and use the
214 * current tsc value as the delta.
215 *
216 * In rare cases we can reach this else clause due to
217 * a lack of monotonicity in the TSC value. In such
218 * cases using the current TSC value as the delta would
219 * cause us to return a value ~2x of what it should
220 * be. To protect against these cases we cap the
221 * suspend/resume delta at tsc_resume_cap.
222 */
223 tsc = tsc_protect(tsc);
224 }
225
226 hrt = tsc_hrtime_base;
227
228 TSC_CONVERT_AND_ADD(tsc, hrt, nsec_scale);
229 } while ((old_hres_lock & ~1) != hres_lock);
230
231 return (hrt);
232 }
233
234 hrtime_t
235 tsc_gethrtime_delta(void)
236 {
237 uint32_t old_hres_lock;
238 hrtime_t tsc, hrt;
239 ulong_t flags;
240
241 do {
242 old_hres_lock = hres_lock;
243
244 /*
245 * We need to disable interrupts here to assure that we
246 * don't migrate between the call to tsc_read() and
247 * adding the CPU's TSC tick delta. Note that disabling
248 * and reenabling preemption is forbidden here because
249 * we may be in the middle of a fast trap. In the amd64
250 * kernel we cannot tolerate preemption during a fast
251 * trap. See _update_sregs().
252 */
253
254 flags = clear_int_flag();
255 tsc = tsc_read() + tsc_sync_tick_delta[CPU->cpu_id];
256 restore_int_flag(flags);
257
258 /* See comments in tsc_gethrtime() above */
259
260 if (tsc >= tsc_last) {
261 tsc -= tsc_last;
262 } else if (tsc >= tsc_last - 2 * tsc_max_delta) {
263 tsc = 0;
264 } else {
265 tsc = tsc_protect(tsc);
266 }
267
268 hrt = tsc_hrtime_base;
269
270 TSC_CONVERT_AND_ADD(tsc, hrt, nsec_scale);
271 } while ((old_hres_lock & ~1) != hres_lock);
272
273 return (hrt);
274 }
275
276 hrtime_t
277 tsc_gethrtime_tick_delta(void)
278 {
279 hrtime_t hrt;
280 ulong_t flags;
281
282 flags = clear_int_flag();
283 hrt = tsc_sync_tick_delta[CPU->cpu_id];
284 restore_int_flag(flags);
285
286 return (hrt);
287 }
288
289 /*
290 * This is similar to the above, but it cannot actually spin on hres_lock.
291 * As a result, it caches all of the variables it needs; if the variables
292 * don't change, it's done.
293 */
294 hrtime_t
295 dtrace_gethrtime(void)
296 {
297 uint32_t old_hres_lock;
298 hrtime_t tsc, hrt;
299 ulong_t flags;
300
301 do {
302 old_hres_lock = hres_lock;
303
304 /*
305 * Interrupts are disabled to ensure that the thread isn't
306 * migrated between the tsc_read() and adding the CPU's
307 * TSC tick delta.
308 */
309 flags = clear_int_flag();
310
311 tsc = tsc_read();
312
313 if (gethrtimef == tsc_gethrtime_delta)
314 tsc += tsc_sync_tick_delta[CPU->cpu_id];
315
316 restore_int_flag(flags);
317
318 /*
319 * See the comments in tsc_gethrtime(), above.
320 */
321 if (tsc >= tsc_last)
322 tsc -= tsc_last;
323 else if (tsc >= tsc_last - 2*tsc_max_delta)
324 tsc = 0;
325 else
326 tsc = tsc_protect(tsc);
327
328 hrt = tsc_hrtime_base;
329
330 TSC_CONVERT_AND_ADD(tsc, hrt, nsec_scale);
331
332 if ((old_hres_lock & ~1) == hres_lock)
333 break;
334
335 /*
336 * If we're here, the clock lock is locked -- or it has been
337 * unlocked and locked since we looked. This may be due to
338 * tsc_tick() running on another CPU -- or it may be because
339 * some code path has ended up in dtrace_probe() with
340 * CLOCK_LOCK held. We'll try to determine that we're in
341 * the former case by taking another lap if the lock has
342 * changed since when we first looked at it.
343 */
344 if (old_hres_lock != hres_lock)
345 continue;
346
347 /*
348 * So the lock was and is locked. We'll use the old data
349 * instead.
350 */
351 old_hres_lock = shadow_hres_lock;
352
353 /*
354 * Again, disable interrupts to ensure that the thread
355 * isn't migrated between the tsc_read() and adding
356 * the CPU's TSC tick delta.
357 */
358 flags = clear_int_flag();
359
360 tsc = tsc_read();
361
362 if (gethrtimef == tsc_gethrtime_delta)
363 tsc += tsc_sync_tick_delta[CPU->cpu_id];
364
365 restore_int_flag(flags);
366
367 /*
368 * See the comments in tsc_gethrtime(), above.
369 */
370 if (tsc >= shadow_tsc_last)
371 tsc -= shadow_tsc_last;
372 else if (tsc >= shadow_tsc_last - 2 * tsc_max_delta)
373 tsc = 0;
374 else
375 tsc = tsc_protect(tsc);
376
377 hrt = shadow_tsc_hrtime_base;
378
379 TSC_CONVERT_AND_ADD(tsc, hrt, shadow_nsec_scale);
380 } while ((old_hres_lock & ~1) != shadow_hres_lock);
381
382 return (hrt);
383 }
384
385 hrtime_t
386 tsc_gethrtimeunscaled(void)
387 {
388 uint32_t old_hres_lock;
389 hrtime_t tsc;
390
391 do {
392 old_hres_lock = hres_lock;
393
394 /* See tsc_tick(). */
395 tsc = tsc_read() + tsc_last_jumped;
396 } while ((old_hres_lock & ~1) != hres_lock);
397
398 return (tsc);
399 }
400
401 /*
402 * Convert a nanosecond based timestamp to tsc
403 */
404 uint64_t
405 tsc_unscalehrtime(hrtime_t nsec)
406 {
407 hrtime_t tsc;
408
409 if (tsc_gethrtime_enable) {
410 TSC_CONVERT(nsec, tsc, nsec_unscale);
411 return (tsc);
412 }
413 return ((uint64_t)nsec);
414 }
415
416 /* Convert a tsc timestamp to nanoseconds */
417 void
418 tsc_scalehrtime(hrtime_t *tsc)
419 {
420 hrtime_t hrt;
421 hrtime_t mytsc;
422
423 if (tsc == NULL)
424 return;
425 mytsc = *tsc;
426
427 TSC_CONVERT(mytsc, hrt, nsec_scale);
428 *tsc = hrt;
429 }
430
431 hrtime_t
432 tsc_gethrtimeunscaled_delta(void)
433 {
434 hrtime_t hrt;
435 ulong_t flags;
436
437 /*
438 * Similarly to tsc_gethrtime_delta, we need to disable preemption
439 * to prevent migration between the call to tsc_gethrtimeunscaled
440 * and adding the CPU's hrtime delta. Note that disabling and
441 * reenabling preemption is forbidden here because we may be in the
442 * middle of a fast trap. In the amd64 kernel we cannot tolerate
443 * preemption during a fast trap. See _update_sregs().
444 */
445
446 flags = clear_int_flag();
447 hrt = tsc_gethrtimeunscaled() + tsc_sync_tick_delta[CPU->cpu_id];
448 restore_int_flag(flags);
449
450 return (hrt);
451 }
452
453 /*
454 * Called by the master in the TSC sync operation (usually the boot CPU).
455 * If the slave is discovered to have a skew, gethrtimef will be changed to
456 * point to tsc_gethrtime_delta(). Calculating skews is precise only when
457 * the master and slave TSCs are read simultaneously; however, there is no
458 * algorithm that can read both CPUs in perfect simultaneity. The proposed
459 * algorithm is an approximate method based on the behaviour of cache
460 * management. The slave CPU continuously reads TSC and then reads a global
461 * variable which the master CPU updates. The moment the master's update reaches
462 * the slave's visibility (being forced by an mfence operation) we use the TSC
463 * reading taken on the slave. A corresponding TSC read will be taken on the
464 * master as soon as possible after finishing the mfence operation. But the
465 * delay between causing the slave to notice the invalid cache line and the
466 * competion of mfence is not repeatable. This error is heuristically assumed
467 * to be 1/4th of the total write time as being measured by the two TSC reads
468 * on the master sandwiching the mfence. Furthermore, due to the nature of
469 * bus arbitration, contention on memory bus, etc., the time taken for the write
470 * to reflect globally can vary a lot. So instead of taking a single reading,
471 * a set of readings are taken and the one with least write time is chosen
472 * to calculate the final skew.
473 *
474 * TSC sync is disabled in the context of virtualization because the CPUs
475 * assigned to the guest are virtual CPUs which means the real CPUs on which
476 * guest runs keep changing during life time of guest OS. So we would end up
477 * calculating TSC skews for a set of CPUs during boot whereas the guest
478 * might migrate to a different set of physical CPUs at a later point of
479 * time.
480 */
481 void
482 tsc_sync_master(processorid_t slave)
483 {
484 ulong_t flags, source, min_write_time = ~0UL;
485 hrtime_t write_time, x, mtsc_after, tdelta;
486 tsc_sync_t *tsc = tscp;
487 int cnt;
488 int hwtype;
489
490 hwtype = get_hwenv();
491 if (!tsc_master_slave_sync_needed || (hwtype & HW_VIRTUAL) != 0)
492 return;
493
494 flags = clear_int_flag();
495 source = CPU->cpu_id;
496
497 for (cnt = 0; cnt < SYNC_ITERATIONS; cnt++) {
498 while (tsc_sync_go != TSC_SYNC_GO)
499 SMT_PAUSE();
500
501 tsc->master_tsc = tsc_read();
502 membar_enter();
503 mtsc_after = tsc_read();
504 while (tsc_sync_go != TSC_SYNC_DONE)
505 SMT_PAUSE();
506 write_time = mtsc_after - tsc->master_tsc;
507 if (write_time <= min_write_time) {
508 min_write_time = write_time;
509 /*
510 * Apply heuristic adjustment only if the calculated
511 * delta is > 1/4th of the write time.
512 */
513 x = tsc->slave_tsc - mtsc_after;
514 if (x < 0)
515 x = -x;
516 if (x > (min_write_time/4))
517 /*
518 * Subtract 1/4th of the measured write time
519 * from the master's TSC value, as an estimate
520 * of how late the mfence completion came
521 * after the slave noticed the cache line
522 * change.
523 */
524 tdelta = tsc->slave_tsc -
525 (mtsc_after - (min_write_time/4));
526 else
527 tdelta = tsc->slave_tsc - mtsc_after;
528 tsc_sync_tick_delta[slave] =
529 tsc_sync_tick_delta[source] - tdelta;
530 }
531
532 tsc->master_tsc = tsc->slave_tsc = write_time = 0;
533 membar_enter();
534 tsc_sync_go = TSC_SYNC_STOP;
535 }
536 if (tdelta < 0)
537 tdelta = -tdelta;
538 if (tdelta > largest_tsc_delta)
539 largest_tsc_delta = tdelta;
540 if (min_write_time < shortest_write_time)
541 shortest_write_time = min_write_time;
542 /*
543 * Enable delta variants of tsc functions if the largest of all chosen
544 * deltas is > smallest of the write time.
545 */
546 if (largest_tsc_delta > shortest_write_time) {
547 gethrtimef = tsc_gethrtime_delta;
548 gethrtimeunscaledf = tsc_gethrtimeunscaled_delta;
549 }
550 restore_int_flag(flags);
551 }
552
553 /*
554 * Called by a CPU which has just been onlined. It is expected that the CPU
555 * performing the online operation will call tsc_sync_master().
556 *
557 * TSC sync is disabled in the context of virtualization. See comments
558 * above tsc_sync_master.
559 */
560 void
561 tsc_sync_slave(void)
562 {
563 ulong_t flags;
564 hrtime_t s1;
565 tsc_sync_t *tsc = tscp;
566 int cnt;
567 int hwtype;
568
569 hwtype = get_hwenv();
570 if (!tsc_master_slave_sync_needed || (hwtype & HW_VIRTUAL) != 0)
571 return;
572
573 flags = clear_int_flag();
574
575 for (cnt = 0; cnt < SYNC_ITERATIONS; cnt++) {
576 /* Re-fill the cache line */
577 s1 = tsc->master_tsc;
578 membar_enter();
579 tsc_sync_go = TSC_SYNC_GO;
580 do {
581 /*
582 * Do not put an SMT_PAUSE here. For instance,
583 * if the master and slave are really the same
584 * hyper-threaded CPU, then you want the master
585 * to yield to the slave as quickly as possible here,
586 * but not the other way.
587 */
588 s1 = tsc_read();
589 } while (tsc->master_tsc == 0);
590 tsc->slave_tsc = s1;
591 membar_enter();
592 tsc_sync_go = TSC_SYNC_DONE;
593
594 while (tsc_sync_go != TSC_SYNC_STOP)
595 SMT_PAUSE();
596 }
597
598 restore_int_flag(flags);
599 }
600
601 /*
602 * Called once per second on a CPU from the cyclic subsystem's
603 * CY_HIGH_LEVEL interrupt. (No longer just cpu0-only)
604 */
605 void
606 tsc_tick(void)
607 {
608 hrtime_t now, delta;
609 ushort_t spl;
610
611 /*
612 * Before we set the new variables, we set the shadow values. This
613 * allows for lock free operation in dtrace_gethrtime().
614 */
615 lock_set_spl((lock_t *)&shadow_hres_lock + HRES_LOCK_OFFSET,
616 ipltospl(CBE_HIGH_PIL), &spl);
617
618 shadow_tsc_hrtime_base = tsc_hrtime_base;
619 shadow_tsc_last = tsc_last;
620 shadow_nsec_scale = nsec_scale;
621
622 shadow_hres_lock++;
623 splx(spl);
624
625 CLOCK_LOCK(&spl);
626
627 now = tsc_read();
628
629 if (gethrtimef == tsc_gethrtime_delta)
630 now += tsc_sync_tick_delta[CPU->cpu_id];
631
632 if (now < tsc_last) {
633 /*
634 * The TSC has just jumped into the past. We assume that
635 * this is due to a suspend/resume cycle, and we're going
636 * to use the _current_ value of TSC as the delta. This
637 * will keep tsc_hrtime_base correct. We're also going to
638 * assume that rate of tsc does not change after a suspend
639 * resume (i.e nsec_scale remains the same).
640 */
641 delta = now;
642 delta = tsc_protect(delta);
643 tsc_last_jumped += tsc_last;
644 tsc_jumped = 1;
645 } else {
646 /*
647 * Determine the number of TSC ticks since the last clock
648 * tick, and add that to the hrtime base.
649 */
650 delta = now - tsc_last;
651 }
652
653 TSC_CONVERT_AND_ADD(delta, tsc_hrtime_base, nsec_scale);
654 tsc_last = now;
655
656 CLOCK_UNLOCK(spl);
657 }
658
659 void
660 tsc_hrtimeinit(uint64_t cpu_freq_hz)
661 {
662 extern int gethrtime_hires;
663 longlong_t tsc;
664 ulong_t flags;
665
666 /*
667 * cpu_freq_hz is the measured cpu frequency in hertz
668 */
669
670 /*
671 * We can't accommodate CPUs slower than 31.25 MHz.
672 */
673 ASSERT(cpu_freq_hz > NANOSEC / (1 << NSEC_SHIFT));
674 nsec_scale =
675 (uint_t)(((uint64_t)NANOSEC << (32 - NSEC_SHIFT)) / cpu_freq_hz);
676 nsec_unscale =
677 (uint_t)(((uint64_t)cpu_freq_hz << (32 - NSEC_SHIFT)) / NANOSEC);
678
679 flags = clear_int_flag();
680 tsc = tsc_read();
681 (void) tsc_gethrtime();
682 tsc_max_delta = tsc_read() - tsc;
683 restore_int_flag(flags);
684 gethrtimef = tsc_gethrtime;
685 gethrtimeunscaledf = tsc_gethrtimeunscaled;
686 scalehrtimef = tsc_scalehrtime;
687 unscalehrtimef = tsc_unscalehrtime;
688 hrtime_tick = tsc_tick;
689 gethrtime_hires = 1;
690 /*
691 * Allocate memory for the structure used in the tsc sync logic.
692 * This structure should be aligned on a multiple of cache line size.
693 */
694 tscp = kmem_zalloc(PAGESIZE, KM_SLEEP);
695
696 /*
697 * Convert the TSC resume cap ns value into its unscaled TSC value.
698 * See tsc_gethrtime().
699 */
700 if (tsc_resume_cap == 0)
701 TSC_CONVERT(tsc_resume_cap_ns, tsc_resume_cap, nsec_unscale);
702 }
703
704 int
705 get_tsc_ready()
706 {
707 return (tsc_ready);
708 }
709
710 /*
711 * Adjust all the deltas by adding the passed value to the array.
712 * Then use the "delt" versions of the the gethrtime functions.
713 * Note that 'tdelta' _could_ be a negative number, which should
714 * reduce the values in the array (used, for example, if the Solaris
715 * instance was moved by a virtual manager to a machine with a higher
716 * value of tsc).
717 */
718 void
719 tsc_adjust_delta(hrtime_t tdelta)
720 {
721 int i;
722
723 for (i = 0; i < NCPU; i++) {
724 tsc_sync_tick_delta[i] += tdelta;
725 }
726
727 gethrtimef = tsc_gethrtime_delta;
728 gethrtimeunscaledf = tsc_gethrtimeunscaled_delta;
729 }
730
731 /*
732 * Functions to manage TSC and high-res time on suspend and resume.
733 */
734
735 /*
736 * declarations needed for time adjustment
737 */
738 extern void rtcsync(void);
739 extern tod_ops_t *tod_ops;
740 /* There must be a better way than exposing nsec_scale! */
741 extern uint_t nsec_scale;
742 static uint64_t tsc_saved_tsc = 0; /* 1 in 2^64 chance this'll screw up! */
743 static timestruc_t tsc_saved_ts;
744 static int tsc_needs_resume = 0; /* We only want to do this once. */
745 int tsc_delta_onsuspend = 0;
746 int tsc_adjust_seconds = 1;
747 int tsc_suspend_count = 0;
748 int tsc_resume_in_cyclic = 0;
749
750 /*
751 * Let timestamp.c know that we are suspending. It needs to take
752 * snapshots of the current time, and do any pre-suspend work.
753 */
754 void
755 tsc_suspend(void)
756 {
757 /*
758 * What we need to do here, is to get the time we suspended, so that we
759 * know how much we should add to the resume.
760 * This routine is called by each CPU, so we need to handle reentry.
761 */
762 if (tsc_gethrtime_enable) {
763 /*
764 * We put the tsc_read() inside the lock as it
765 * as no locking constraints, and it puts the
766 * aquired value closer to the time stamp (in
767 * case we delay getting the lock).
768 */
769 mutex_enter(&tod_lock);
770 tsc_saved_tsc = tsc_read();
771 tsc_saved_ts = TODOP_GET(tod_ops);
772 mutex_exit(&tod_lock);
773 /* We only want to do this once. */
774 if (tsc_needs_resume == 0) {
775 if (tsc_delta_onsuspend) {
776 tsc_adjust_delta(tsc_saved_tsc);
777 } else {
778 tsc_adjust_delta(nsec_scale);
779 }
780 tsc_suspend_count++;
781 }
782 }
783
784 invalidate_cache();
785 tsc_needs_resume = 1;
786 }
787
788 /*
789 * Restore all timestamp state based on the snapshots taken at
790 * suspend time.
791 */
792 void
793 tsc_resume(void)
794 {
795 /*
796 * We only need to (and want to) do this once. So let the first
797 * caller handle this (we are locked by the cpu lock), as it
798 * is preferential that we get the earliest sync.
799 */
800 if (tsc_needs_resume) {
801 /*
802 * If using the TSC, adjust the delta based on how long
803 * we were sleeping (or away). We also adjust for
804 * migration and a grown TSC.
805 */
806 if (tsc_saved_tsc != 0) {
807 timestruc_t ts;
808 hrtime_t now, sleep_tsc = 0;
809 int sleep_sec;
810 extern void tsc_tick(void);
811 extern uint64_t cpu_freq_hz;
812
813 /* tsc_read() MUST be before TODOP_GET() */
814 mutex_enter(&tod_lock);
815 now = tsc_read();
816 ts = TODOP_GET(tod_ops);
817 mutex_exit(&tod_lock);
818
819 /* Compute seconds of sleep time */
820 sleep_sec = ts.tv_sec - tsc_saved_ts.tv_sec;
821
822 /*
823 * If the saved sec is less that or equal to
824 * the current ts, then there is likely a
825 * problem with the clock. Assume at least
826 * one second has passed, so that time goes forward.
827 */
828 if (sleep_sec <= 0) {
829 sleep_sec = 1;
830 }
831
832 /* How many TSC's should have occured while sleeping */
833 if (tsc_adjust_seconds)
834 sleep_tsc = sleep_sec * cpu_freq_hz;
835
836 /*
837 * We also want to subtract from the "sleep_tsc"
838 * the current value of tsc_read(), so that our
839 * adjustment accounts for the amount of time we
840 * have been resumed _or_ an adjustment based on
841 * the fact that we didn't actually power off the
842 * CPU (migration is another issue, but _should_
843 * also comply with this calculation). If the CPU
844 * never powered off, then:
845 * 'now == sleep_tsc + saved_tsc'
846 * and the delta will effectively be "0".
847 */
848 sleep_tsc -= now;
849 if (tsc_delta_onsuspend) {
850 tsc_adjust_delta(sleep_tsc);
851 } else {
852 tsc_adjust_delta(tsc_saved_tsc + sleep_tsc);
853 }
854 tsc_saved_tsc = 0;
855
856 tsc_tick();
857 }
858 tsc_needs_resume = 0;
859 }
860
861 }