summaryrefslogtreecommitdiffstats
path: root/sys/kern/kern_ffclock.c
blob: 07441cd2c95e1199c21e12b7b4cd0b6d2a58a2b8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
/*-
 * Copyright (c) 2011 The University of Melbourne
 * All rights reserved.
 *
 * This software was developed by Julien Ridoux at the University of Melbourne
 * under sponsorship from the FreeBSD Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_ffclock.h"

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/sbuf.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/timeffc.h>

#ifdef FFCLOCK

FEATURE(ffclock, "Feed-forward clock support");

extern struct ffclock_estimate ffclock_estimate;
extern struct bintime ffclock_boottime;
extern int8_t ffclock_updated;
extern struct mtx ffclock_mtx;

/*
 * Feed-forward clock absolute time. This should be the preferred way to read
 * the feed-forward clock for "wall-clock" type time. The flags allow to compose
 * various flavours of absolute time (e.g. with or without leap seconds taken
 * into account). If valid pointers are provided, the ffcounter value and an
 * upper bound on clock error associated with the bintime are provided.
 * NOTE: use ffclock_convert_abs() to differ the conversion of a ffcounter value
 * read earlier.
 */
void
ffclock_abstime(ffcounter *ffcount, struct bintime *bt,
    struct bintime *error_bound, uint32_t flags)
{
	struct ffclock_estimate cest;
	ffcounter ffc;
	ffcounter update_ffcount;
	ffcounter ffdelta_error;

	/* Get counter and corresponding time. */
	if ((flags & FFCLOCK_FAST) == FFCLOCK_FAST)
		ffclock_last_tick(&ffc, bt, flags);
	else {
		ffclock_read_counter(&ffc);
		ffclock_convert_abs(ffc, bt, flags);
	}

	/* Current ffclock estimate, use update_ffcount as generation number. */
	do {
		update_ffcount = ffclock_estimate.update_ffcount;
		bcopy(&ffclock_estimate, &cest, sizeof(struct ffclock_estimate));
	} while (update_ffcount != ffclock_estimate.update_ffcount);

	/*
	 * Leap second adjustment. Total as seen by synchronisation algorithm
	 * since it started. cest.leapsec_next is the ffcounter prediction of
	 * when the next leapsecond occurs.
	 */
	if ((flags & FFCLOCK_LEAPSEC) == FFCLOCK_LEAPSEC) {
		bt->sec -= cest.leapsec_total;
		if (ffc > cest.leapsec_next)
			bt->sec -= cest.leapsec;
	}

	/* Boot time adjustment, for uptime/monotonic clocks. */
	if ((flags & FFCLOCK_UPTIME) == FFCLOCK_UPTIME) {
		bintime_sub(bt, &ffclock_boottime);
	}

	/* Compute error bound if a valid pointer has been passed. */
	if (error_bound) {
		ffdelta_error = ffc - cest.update_ffcount;
		ffclock_convert_diff(ffdelta_error, error_bound);
		/* 18446744073709 = int(2^64/1e12), err_bound_rate in [ps/s] */
		bintime_mul(error_bound, cest.errb_rate *
		    (uint64_t)18446744073709LL);
		/* 18446744073 = int(2^64 / 1e9), since err_abs in [ns] */
		bintime_addx(error_bound, cest.errb_abs *
		    (uint64_t)18446744073LL);
	}

	if (ffcount)
		*ffcount = ffc;
}

/*
 * Feed-forward difference clock. This should be the preferred way to convert a
 * time interval in ffcounter values into a time interval in seconds. If a valid
 * pointer is passed, an upper bound on the error in computing the time interval
 * in seconds is provided.
 */
void
ffclock_difftime(ffcounter ffdelta, struct bintime *bt,
    struct bintime *error_bound)
{
	ffcounter update_ffcount;
	uint32_t err_rate;

	ffclock_convert_diff(ffdelta, bt);

	if (error_bound) {
		do {
			update_ffcount = ffclock_estimate.update_ffcount;
			err_rate = ffclock_estimate.errb_rate;
		} while (update_ffcount != ffclock_estimate.update_ffcount);

		ffclock_convert_diff(ffdelta, error_bound);
		/* 18446744073709 = int(2^64/1e12), err_bound_rate in [ps/s] */
		bintime_mul(error_bound, err_rate * (uint64_t)18446744073709LL);
	}
}

/*
 * Create a new kern.sysclock sysctl node, which will be home to some generic
 * sysclock configuration variables. Feed-forward clock specific variables will
 * live under the ffclock subnode.
 */

SYSCTL_NODE(_kern, OID_AUTO, sysclock, CTLFLAG_RW, 0,
    "System clock related configuration");
SYSCTL_NODE(_kern_sysclock, OID_AUTO, ffclock, CTLFLAG_RW, 0,
    "Feed-forward clock configuration");

static char *sysclocks[] = {"feedback", "feed-forward"};
#define	MAX_SYSCLOCK_NAME_LEN 16
#define	NUM_SYSCLOCKS (sizeof(sysclocks) / sizeof(*sysclocks))

static int ffclock_version = 2;
SYSCTL_INT(_kern_sysclock_ffclock, OID_AUTO, version, CTLFLAG_RD,
    &ffclock_version, 0, "Feed-forward clock kernel version");

/* List available sysclocks. */
static int
sysctl_kern_sysclock_available(SYSCTL_HANDLER_ARGS)
{
	struct sbuf *s;
	int clk, error;

	s = sbuf_new_for_sysctl(NULL, NULL,
	    MAX_SYSCLOCK_NAME_LEN * NUM_SYSCLOCKS, req);
	if (s == NULL)
		return (ENOMEM);

	for (clk = 0; clk < NUM_SYSCLOCKS; clk++) {
		sbuf_cat(s, sysclocks[clk]);
		if (clk + 1 < NUM_SYSCLOCKS)
			sbuf_cat(s, " ");
	}
	error = sbuf_finish(s);
	sbuf_delete(s);

	return (error);
}

SYSCTL_PROC(_kern_sysclock, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD,
    0, 0, sysctl_kern_sysclock_available, "A",
    "List of available system clocks");

/*
 * Return the name of the active system clock if read, or attempt to change
 * the active system clock to the user specified one if written to. The active
 * system clock is read when calling any of the [get]{bin,nano,micro}[up]time()
 * functions.
 */
static int
sysctl_kern_sysclock_active(SYSCTL_HANDLER_ARGS)
{
	char newclock[MAX_SYSCLOCK_NAME_LEN];
	int clk, error;

	if (req->newptr == NULL) {
		/* Return the name of the current active sysclock. */
		strlcpy(newclock, sysclocks[sysclock_active], sizeof(newclock));
		error = sysctl_handle_string(oidp, newclock,
		    sizeof(newclock), req);
	} else {
		/* Change the active sysclock to the user specified one. */
		error = EINVAL;
		for (clk = 0; clk < NUM_SYSCLOCKS; clk++) {
			if (strncmp((char *)req->newptr, sysclocks[clk],
			    strlen(sysclocks[clk])) == 0) {
				sysclock_active = clk;
				error = 0;
				break;
			}
		}
	}

	return (error);
}

SYSCTL_PROC(_kern_sysclock, OID_AUTO, active, CTLTYPE_STRING | CTLFLAG_RW,
    0, 0, sysctl_kern_sysclock_active, "A",
    "Name of the active system clock which is currently serving time");

static int sysctl_kern_ffclock_ffcounter_bypass = 0;
SYSCTL_INT(_kern_sysclock_ffclock, OID_AUTO, ffcounter_bypass, CTLFLAG_RW,
    &sysctl_kern_ffclock_ffcounter_bypass, 0,
    "Use reliable hardware timecounter as the feed-forward counter");

/*
 * High level functions to access the Feed-Forward Clock.
 */
void
ffclock_bintime(struct bintime *bt)
{

	ffclock_abstime(NULL, bt, NULL, FFCLOCK_LERP | FFCLOCK_LEAPSEC);
}

void
ffclock_nanotime(struct timespec *tsp)
{
	struct bintime bt;

	ffclock_abstime(NULL, &bt, NULL, FFCLOCK_LERP | FFCLOCK_LEAPSEC);
	bintime2timespec(&bt, tsp);
}

void
ffclock_microtime(struct timeval *tvp)
{
	struct bintime bt;

	ffclock_abstime(NULL, &bt, NULL, FFCLOCK_LERP | FFCLOCK_LEAPSEC);
	bintime2timeval(&bt, tvp);
}

void
ffclock_getbintime(struct bintime *bt)
{

	ffclock_abstime(NULL, bt, NULL,
	    FFCLOCK_LERP | FFCLOCK_LEAPSEC | FFCLOCK_FAST);
}

void
ffclock_getnanotime(struct timespec *tsp)
{
	struct bintime bt;

	ffclock_abstime(NULL, &bt, NULL,
	    FFCLOCK_LERP | FFCLOCK_LEAPSEC | FFCLOCK_FAST);
	bintime2timespec(&bt, tsp);
}

void
ffclock_getmicrotime(struct timeval *tvp)
{
	struct bintime bt;

	ffclock_abstime(NULL, &bt, NULL,
	    FFCLOCK_LERP | FFCLOCK_LEAPSEC | FFCLOCK_FAST);
	bintime2timeval(&bt, tvp);
}

void
ffclock_binuptime(struct bintime *bt)
{

	ffclock_abstime(NULL, bt, NULL, FFCLOCK_LERP | FFCLOCK_UPTIME);
}

void
ffclock_nanouptime(struct timespec *tsp)
{
	struct bintime bt;

	ffclock_abstime(NULL, &bt, NULL, FFCLOCK_LERP | FFCLOCK_UPTIME);
	bintime2timespec(&bt, tsp);
}

void
ffclock_microuptime(struct timeval *tvp)
{
	struct bintime bt;

	ffclock_abstime(NULL, &bt, NULL, FFCLOCK_LERP | FFCLOCK_UPTIME);
	bintime2timeval(&bt, tvp);
}

void
ffclock_getbinuptime(struct bintime *bt)
{

	ffclock_abstime(NULL, bt, NULL,
	    FFCLOCK_LERP | FFCLOCK_UPTIME | FFCLOCK_FAST);
}

void
ffclock_getnanouptime(struct timespec *tsp)
{
	struct bintime bt;

	ffclock_abstime(NULL, &bt, NULL,
	    FFCLOCK_LERP | FFCLOCK_UPTIME | FFCLOCK_FAST);
	bintime2timespec(&bt, tsp);
}

void
ffclock_getmicrouptime(struct timeval *tvp)
{
	struct bintime bt;

	ffclock_abstime(NULL, &bt, NULL,
	    FFCLOCK_LERP | FFCLOCK_UPTIME | FFCLOCK_FAST);
	bintime2timeval(&bt, tvp);
}

void
ffclock_bindifftime(ffcounter ffdelta, struct bintime *bt)
{

	ffclock_difftime(ffdelta, bt, NULL);
}

void
ffclock_nanodifftime(ffcounter ffdelta, struct timespec *tsp)
{
	struct bintime bt;

	ffclock_difftime(ffdelta, &bt, NULL);
	bintime2timespec(&bt, tsp);
}

void
ffclock_microdifftime(ffcounter ffdelta, struct timeval *tvp)
{
	struct bintime bt;

	ffclock_difftime(ffdelta, &bt, NULL);
	bintime2timeval(&bt, tvp);
}

/*
 * System call allowing userland applications to retrieve the current value of
 * the Feed-Forward Clock counter.
 */
#ifndef _SYS_SYSPROTO_H_
struct ffclock_getcounter_args {
	ffcounter *ffcount;
};
#endif
/* ARGSUSED */
int
sys_ffclock_getcounter(struct thread *td, struct ffclock_getcounter_args *uap)
{
	ffcounter ffcount;
	int error;

	ffcount = 0;
	ffclock_read_counter(&ffcount);
	if (ffcount == 0)
		return (EAGAIN);
	error = copyout(&ffcount, uap->ffcount, sizeof(ffcounter));

	return (error);
}

/*
 * System call allowing the synchronisation daemon to push new feed-foward clock
 * estimates to the kernel. Acquire ffclock_mtx to prevent concurrent updates
 * and ensure data consistency.
 * NOTE: ffclock_updated signals the fftimehands that new estimates are
 * available. The updated estimates are picked up by the fftimehands on next
 * tick, which could take as long as 1/hz seconds (if ticks are not missed).
 */
#ifndef _SYS_SYSPROTO_H_
struct ffclock_setestimate_args {
	struct ffclock_estimate *cest;
};
#endif
/* ARGSUSED */
int
sys_ffclock_setestimate(struct thread *td, struct ffclock_setestimate_args *uap)
{
	struct ffclock_estimate cest;
	int error;

	/* Reuse of PRIV_CLOCK_SETTIME. */
	if ((error = priv_check(td, PRIV_CLOCK_SETTIME)) != 0)
		return (error);

	if ((error = copyin(uap->cest, &cest, sizeof(struct ffclock_estimate)))
	    != 0)
		return (error);

	mtx_lock(&ffclock_mtx);
	memcpy(&ffclock_estimate, &cest, sizeof(struct ffclock_estimate));
	ffclock_updated++;
	mtx_unlock(&ffclock_mtx);
	return (error);
}

/*
 * System call allowing userland applications to retrieve the clock estimates
 * stored within the kernel. It is useful to kickstart the synchronisation
 * daemon with the kernel's knowledge of hardware timecounter.
 */
#ifndef _SYS_SYSPROTO_H_
struct ffclock_getestimate_args {
	struct ffclock_estimate *cest;
};
#endif
/* ARGSUSED */
int
sys_ffclock_getestimate(struct thread *td, struct ffclock_getestimate_args *uap)
{
	struct ffclock_estimate cest;
	int error;

	mtx_lock(&ffclock_mtx);
	memcpy(&cest, &ffclock_estimate, sizeof(struct ffclock_estimate));
	mtx_unlock(&ffclock_mtx);
	error = copyout(&cest, uap->cest, sizeof(struct ffclock_estimate));
	return (error);
}

#else /* !FFCLOCK */

int
sys_ffclock_getcounter(struct thread *td, struct ffclock_getcounter_args *uap)
{

	return (ENOSYS);
}

int
sys_ffclock_setestimate(struct thread *td, struct ffclock_setestimate_args *uap)
{

	return (ENOSYS);
}

int
sys_ffclock_getestimate(struct thread *td, struct ffclock_getestimate_args *uap)
{

	return (ENOSYS);
}

#endif /* FFCLOCK */
OpenPOWER on IntegriCloud