1 /*
2  *  Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE
3  *  Copyright 2003 Andi Kleen, SuSE Labs.
4  *
5  *  Modified for x86 32 bit architecture by
6  *  Stefani Seibold <stefani@seibold.net>
7  *  sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany
8  *
9  *  Thanks to hpa@transmeta.com for some useful hint.
10  *  Special thanks to Ingo Molnar for his early experience with
11  *  a different vsyscall implementation for Linux/IA32 and for the name.
12  *
13  */
14 
15 #include <linux/timekeeper_internal.h>
16 #include <asm/vgtod.h>
17 #include <asm/vvar.h>
18 
19 DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data);
20 
update_vsyscall_tz(void)21 void update_vsyscall_tz(void)
22 {
23 	vsyscall_gtod_data.tz_minuteswest = sys_tz.tz_minuteswest;
24 	vsyscall_gtod_data.tz_dsttime = sys_tz.tz_dsttime;
25 }
26 
update_vsyscall(struct timekeeper * tk)27 void update_vsyscall(struct timekeeper *tk)
28 {
29 	struct vsyscall_gtod_data *vdata = &vsyscall_gtod_data;
30 
31 	gtod_write_begin(vdata);
32 
33 	/* copy vsyscall data */
34 	vdata->vclock_mode	= tk->tkr_mono.clock->archdata.vclock_mode;
35 	vdata->cycle_last	= tk->tkr_mono.cycle_last;
36 	vdata->mask		= tk->tkr_mono.mask;
37 	vdata->mult		= tk->tkr_mono.mult;
38 	vdata->shift		= tk->tkr_mono.shift;
39 
40 	vdata->wall_time_sec		= tk->xtime_sec;
41 	vdata->wall_time_snsec		= tk->tkr_mono.xtime_nsec;
42 
43 	vdata->monotonic_time_sec	= tk->xtime_sec
44 					+ tk->wall_to_monotonic.tv_sec;
45 	vdata->monotonic_time_snsec	= tk->tkr_mono.xtime_nsec
46 					+ ((u64)tk->wall_to_monotonic.tv_nsec
47 						<< tk->tkr_mono.shift);
48 	while (vdata->monotonic_time_snsec >=
49 					(((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
50 		vdata->monotonic_time_snsec -=
51 					((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
52 		vdata->monotonic_time_sec++;
53 	}
54 
55 	vdata->wall_time_coarse_sec	= tk->xtime_sec;
56 	vdata->wall_time_coarse_nsec	= (long)(tk->tkr_mono.xtime_nsec >>
57 						 tk->tkr_mono.shift);
58 
59 	vdata->monotonic_time_coarse_sec =
60 		vdata->wall_time_coarse_sec + tk->wall_to_monotonic.tv_sec;
61 	vdata->monotonic_time_coarse_nsec =
62 		vdata->wall_time_coarse_nsec + tk->wall_to_monotonic.tv_nsec;
63 
64 	while (vdata->monotonic_time_coarse_nsec >= NSEC_PER_SEC) {
65 		vdata->monotonic_time_coarse_nsec -= NSEC_PER_SEC;
66 		vdata->monotonic_time_coarse_sec++;
67 	}
68 
69 	gtod_write_end(vdata);
70 }
71