1#ifndef _ASM_X86_VGTOD_H
2#define _ASM_X86_VGTOD_H
3
4#include <linux/compiler.h>
5#include <linux/clocksource.h>
6
7#ifdef BUILD_VDSO32_64
8typedef u64 gtod_long_t;
9#else
10typedef unsigned long gtod_long_t;
11#endif
12/*
13 * vsyscall_gtod_data will be accessed by 32 and 64 bit code at the same time
14 * so be carefull by modifying this structure.
15 */
16struct vsyscall_gtod_data {
17	unsigned seq;
18
19	int vclock_mode;
20	cycle_t	cycle_last;
21	cycle_t	mask;
22	u32	mult;
23	u32	shift;
24
25	/* open coded 'struct timespec' */
26	u64		wall_time_snsec;
27	gtod_long_t	wall_time_sec;
28	gtod_long_t	monotonic_time_sec;
29	u64		monotonic_time_snsec;
30	gtod_long_t	wall_time_coarse_sec;
31	gtod_long_t	wall_time_coarse_nsec;
32	gtod_long_t	monotonic_time_coarse_sec;
33	gtod_long_t	monotonic_time_coarse_nsec;
34
35	int		tz_minuteswest;
36	int		tz_dsttime;
37};
38extern struct vsyscall_gtod_data vsyscall_gtod_data;
39
40static inline unsigned gtod_read_begin(const struct vsyscall_gtod_data *s)
41{
42	unsigned ret;
43
44repeat:
45	ret = ACCESS_ONCE(s->seq);
46	if (unlikely(ret & 1)) {
47		cpu_relax();
48		goto repeat;
49	}
50	smp_rmb();
51	return ret;
52}
53
54static inline int gtod_read_retry(const struct vsyscall_gtod_data *s,
55					unsigned start)
56{
57	smp_rmb();
58	return unlikely(s->seq != start);
59}
60
61static inline void gtod_write_begin(struct vsyscall_gtod_data *s)
62{
63	++s->seq;
64	smp_wmb();
65}
66
67static inline void gtod_write_end(struct vsyscall_gtod_data *s)
68{
69	smp_wmb();
70	++s->seq;
71}
72
73#ifdef CONFIG_X86_64
74
75#define VGETCPU_CPU_MASK 0xfff
76
77static inline unsigned int __getcpu(void)
78{
79	unsigned int p;
80
81	/*
82	 * Load per CPU data from GDT.  LSL is faster than RDTSCP and
83	 * works on all CPUs.  This is volatile so that it orders
84	 * correctly wrt barrier() and to keep gcc from cleverly
85	 * hoisting it out of the calling function.
86	 */
87	asm volatile ("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
88
89	return p;
90}
91
92#endif /* CONFIG_X86_64 */
93
94#endif /* _ASM_X86_VGTOD_H */
95