summaryrefslogtreecommitdiff
path: root/lib/vdso/gettimeofday.c
blob: 899850bd6f0bee5853d6f5ffb779af1b218e5adb (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Generic userspace implementations of gettimeofday() and similar.
 */
#include <vdso/datapage.h>
#include <vdso/helpers.h>

#ifndef vdso_calc_ns

#ifdef VDSO_DELTA_NOMASK
# define VDSO_DELTA_MASK(vd)	ULLONG_MAX
#else
# define VDSO_DELTA_MASK(vd)	(vd->mask)
#endif

#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
static __always_inline bool vdso_delta_ok(const struct vdso_data *vd, u64 delta)
{
	return delta < vd->max_cycles;
}
#else
static __always_inline bool vdso_delta_ok(const struct vdso_data *vd, u64 delta)
{
	return true;
}
#endif

#ifndef vdso_shift_ns
static __always_inline u64 vdso_shift_ns(u64 ns, u32 shift)
{
	return ns >> shift;
}
#endif

/*
 * Default implementation which works for all sane clocksources. That
 * obviously excludes x86/TSC.
 */
static __always_inline u64 vdso_calc_ns(const struct vdso_data *vd, u64 cycles, u64 base)
{
	u64 delta = (cycles - vd->cycle_last) & VDSO_DELTA_MASK(vd);

	if (likely(vdso_delta_ok(vd, delta)))
		return vdso_shift_ns((delta * vd->mult) + base, vd->shift);

	return mul_u64_u32_add_u64_shr(delta, vd->mult, base, vd->shift);
}
#endif /* vdso_calc_ns */

#ifndef __arch_vdso_hres_capable
static inline bool __arch_vdso_hres_capable(void)
{
	return true;
}
#endif

#ifndef vdso_clocksource_ok
static inline bool vdso_clocksource_ok(const struct vdso_data *vd)
{
	return vd->clock_mode != VDSO_CLOCKMODE_NONE;
}
#endif

#ifndef vdso_cycles_ok
static inline bool vdso_cycles_ok(u64 cycles)
{
	return true;
}
#endif

#ifdef CONFIG_TIME_NS
static __always_inline int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
					  struct __kernel_timespec *ts)
{
	const struct timens_offset *offs = &vdns->offset[clk];
	const struct vdso_timestamp *vdso_ts;
	const struct vdso_data *vd;
	u64 cycles, ns;
	u32 seq;
	s64 sec;

	vd = vdns - (clk == CLOCK_MONOTONIC_RAW ? CS_RAW : CS_HRES_COARSE);
	vd = __arch_get_timens_vdso_data(vd);
	if (clk != CLOCK_MONOTONIC_RAW)
		vd = &vd[CS_HRES_COARSE];
	else
		vd = &vd[CS_RAW];
	vdso_ts = &vd->basetime[clk];

	do {
		seq = vdso_read_begin(vd);

		if (unlikely(!vdso_clocksource_ok(vd)))
			return -1;

		cycles = __arch_get_hw_counter(vd->clock_mode, vd);
		if (unlikely(!vdso_cycles_ok(cycles)))
			return -1;
		ns = vdso_calc_ns(vd, cycles, vdso_ts->nsec);
		sec = vdso_ts->sec;
	} while (unlikely(vdso_read_retry(vd, seq)));

	/* Add the namespace offset */
	sec += offs->sec;
	ns += offs->nsec;

	/*
	 * Do this outside the loop: a race inside the loop could result
	 * in __iter_div_u64_rem() being extremely slow.
	 */
	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
	ts->tv_nsec = ns;

	return 0;
}
#else
static __always_inline
const struct vdso_data *__arch_get_timens_vdso_data(const struct vdso_data *vd)
{
	return NULL;
}

static __always_inline int do_hres_timens(const struct vdso_data *vdns, clockid_t clk,
					  struct __kernel_timespec *ts)
{
	return -EINVAL;
}
#endif

static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
				   struct __kernel_timespec *ts)
{
	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
	u64 cycles, sec, ns;
	u32 seq;

	/* Allows to compile the high resolution parts out */
	if (!__arch_vdso_hres_capable())
		return -1;

	do {
		/*
		 * Open coded to handle VDSO_CLOCKMODE_TIMENS. Time namespace
		 * enabled tasks have a special VVAR page installed which
		 * has vd->seq set to 1 and vd->clock_mode set to
		 * VDSO_CLOCKMODE_TIMENS. For non time namespace affected tasks
		 * this does not affect performance because if vd->seq is
		 * odd, i.e. a concurrent update is in progress the extra
		 * check for vd->clock_mode is just a few extra
		 * instructions while spin waiting for vd->seq to become
		 * even again.
		 */
		while (unlikely((seq = READ_ONCE(vd->seq)) & 1)) {
			if (IS_ENABLED(CONFIG_TIME_NS) &&
			    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
				return do_hres_timens(vd, clk, ts);
			cpu_relax();
		}
		smp_rmb();

		if (unlikely(!vdso_clocksource_ok(vd)))
			return -1;

		cycles = __arch_get_hw_counter(vd->clock_mode, vd);
		if (unlikely(!vdso_cycles_ok(cycles)))
			return -1;
		ns = vdso_calc_ns(vd, cycles, vdso_ts->nsec);
		sec = vdso_ts->sec;
	} while (unlikely(vdso_read_retry(vd, seq)));

	/*
	 * Do this outside the loop: a race inside the loop could result
	 * in __iter_div_u64_rem() being extremely slow.
	 */
	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
	ts->tv_nsec = ns;

	return 0;
}

#ifdef CONFIG_TIME_NS
static __always_inline int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
					    struct __kernel_timespec *ts)
{
	const struct vdso_data *vd = __arch_get_timens_vdso_data(vdns);
	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
	const struct timens_offset *offs = &vdns->offset[clk];
	u64 nsec;
	s64 sec;
	s32 seq;

	do {
		seq = vdso_read_begin(vd);
		sec = vdso_ts->sec;
		nsec = vdso_ts->nsec;
	} while (unlikely(vdso_read_retry(vd, seq)));

	/* Add the namespace offset */
	sec += offs->sec;
	nsec += offs->nsec;

	/*
	 * Do this outside the loop: a race inside the loop could result
	 * in __iter_div_u64_rem() being extremely slow.
	 */
	ts->tv_sec = sec + __iter_div_u64_rem(nsec, NSEC_PER_SEC, &nsec);
	ts->tv_nsec = nsec;
	return 0;
}
#else
static __always_inline int do_coarse_timens(const struct vdso_data *vdns, clockid_t clk,
					    struct __kernel_timespec *ts)
{
	return -1;
}
#endif

static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk,
				     struct __kernel_timespec *ts)
{
	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
	u32 seq;

	do {
		/*
		 * Open coded to handle VDSO_CLOCK_TIMENS. See comment in
		 * do_hres().
		 */
		while ((seq = READ_ONCE(vd->seq)) & 1) {
			if (IS_ENABLED(CONFIG_TIME_NS) &&
			    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
				return do_coarse_timens(vd, clk, ts);
			cpu_relax();
		}
		smp_rmb();

		ts->tv_sec = vdso_ts->sec;
		ts->tv_nsec = vdso_ts->nsec;
	} while (unlikely(vdso_read_retry(vd, seq)));

	return 0;
}

static __always_inline int
__cvdso_clock_gettime_common(const struct vdso_data *vd, clockid_t clock,
			     struct __kernel_timespec *ts)
{
	u32 msk;

	/* Check for negative values or invalid clocks */
	if (unlikely((u32) clock >= MAX_CLOCKS))
		return -1;

	/*
	 * Convert the clockid to a bitmask and use it to check which
	 * clocks are handled in the VDSO directly.
	 */
	msk = 1U << clock;
	if (likely(msk & VDSO_HRES))
		vd = &vd[CS_HRES_COARSE];
	else if (msk & VDSO_COARSE)
		return do_coarse(&vd[CS_HRES_COARSE], clock, ts);
	else if (msk & VDSO_RAW)
		vd = &vd[CS_RAW];
	else
		return -1;

	return do_hres(vd, clock, ts);
}

static __maybe_unused int
__cvdso_clock_gettime_data(const struct vdso_data *vd, clockid_t clock,
			   struct __kernel_timespec *ts)
{
	int ret = __cvdso_clock_gettime_common(vd, clock, ts);

	if (unlikely(ret))
		return clock_gettime_fallback(clock, ts);
	return 0;
}

static __maybe_unused int
__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
{
	return __cvdso_clock_gettime_data(__arch_get_vdso_data(), clock, ts);
}

#ifdef BUILD_VDSO32
static __maybe_unused int
__cvdso_clock_gettime32_data(const struct vdso_data *vd, clockid_t clock,
			     struct old_timespec32 *res)
{
	struct __kernel_timespec ts;
	int ret;

	ret = __cvdso_clock_gettime_common(vd, clock, &ts);

	if (unlikely(ret))
		return clock_gettime32_fallback(clock, res);

	/* For ret == 0 */
	res->tv_sec = ts.tv_sec;
	res->tv_nsec = ts.tv_nsec;

	return ret;
}

static __maybe_unused int
__cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
{
	return __cvdso_clock_gettime32_data(__arch_get_vdso_data(), clock, res);
}
#endif /* BUILD_VDSO32 */

static __maybe_unused int
__cvdso_gettimeofday_data(const struct vdso_data *vd,
			  struct __kernel_old_timeval *tv, struct timezone *tz)
{

	if (likely(tv != NULL)) {
		struct __kernel_timespec ts;

		if (do_hres(&vd[CS_HRES_COARSE], CLOCK_REALTIME, &ts))
			return gettimeofday_fallback(tv, tz);

		tv->tv_sec = ts.tv_sec;
		tv->tv_usec = (u32)ts.tv_nsec / NSEC_PER_USEC;
	}

	if (unlikely(tz != NULL)) {
		if (IS_ENABLED(CONFIG_TIME_NS) &&
		    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
			vd = __arch_get_timens_vdso_data(vd);

		tz->tz_minuteswest = vd[CS_HRES_COARSE].tz_minuteswest;
		tz->tz_dsttime = vd[CS_HRES_COARSE].tz_dsttime;
	}

	return 0;
}

static __maybe_unused int
__cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
{
	return __cvdso_gettimeofday_data(__arch_get_vdso_data(), tv, tz);
}

#ifdef VDSO_HAS_TIME
static __maybe_unused __kernel_old_time_t
__cvdso_time_data(const struct vdso_data *vd, __kernel_old_time_t *time)
{
	__kernel_old_time_t t;

	if (IS_ENABLED(CONFIG_TIME_NS) &&
	    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
		vd = __arch_get_timens_vdso_data(vd);

	t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);

	if (time)
		*time = t;

	return t;
}

static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
{
	return __cvdso_time_data(__arch_get_vdso_data(), time);
}
#endif /* VDSO_HAS_TIME */

#ifdef VDSO_HAS_CLOCK_GETRES
static __maybe_unused
int __cvdso_clock_getres_common(const struct vdso_data *vd, clockid_t clock,
				struct __kernel_timespec *res)
{
	u32 msk;
	u64 ns;

	/* Check for negative values or invalid clocks */
	if (unlikely((u32) clock >= MAX_CLOCKS))
		return -1;

	if (IS_ENABLED(CONFIG_TIME_NS) &&
	    vd->clock_mode == VDSO_CLOCKMODE_TIMENS)
		vd = __arch_get_timens_vdso_data(vd);

	/*
	 * Convert the clockid to a bitmask and use it to check which
	 * clocks are handled in the VDSO directly.
	 */
	msk = 1U << clock;
	if (msk & (VDSO_HRES | VDSO_RAW)) {
		/*
		 * Preserves the behaviour of posix_get_hrtimer_res().
		 */
		ns = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
	} else if (msk & VDSO_COARSE) {
		/*
		 * Preserves the behaviour of posix_get_coarse_res().
		 */
		ns = LOW_RES_NSEC;
	} else {
		return -1;
	}

	if (likely(res)) {
		res->tv_sec = 0;
		res->tv_nsec = ns;
	}
	return 0;
}

static __maybe_unused
int __cvdso_clock_getres_data(const struct vdso_data *vd, clockid_t clock,
			      struct __kernel_timespec *res)
{
	int ret = __cvdso_clock_getres_common(vd, clock, res);

	if (unlikely(ret))
		return clock_getres_fallback(clock, res);
	return 0;
}

static __maybe_unused
int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
{
	return __cvdso_clock_getres_data(__arch_get_vdso_data(), clock, res);
}

#ifdef BUILD_VDSO32
static __maybe_unused int
__cvdso_clock_getres_time32_data(const struct vdso_data *vd, clockid_t clock,
				 struct old_timespec32 *res)
{
	struct __kernel_timespec ts;
	int ret;

	ret = __cvdso_clock_getres_common(vd, clock, &ts);

	if (unlikely(ret))
		return clock_getres32_fallback(clock, res);

	if (likely(res)) {
		res->tv_sec = ts.tv_sec;
		res->tv_nsec = ts.tv_nsec;
	}
	return ret;
}

static __maybe_unused int
__cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
{
	return __cvdso_clock_getres_time32_data(__arch_get_vdso_data(),
						clock, res);
}
#endif /* BUILD_VDSO32 */
#endif /* VDSO_HAS_CLOCK_GETRES */