1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __VDSO_DATAPAGE_H
3#define __VDSO_DATAPAGE_H
4
5#ifndef __ASSEMBLY__
6
7#include <linux/compiler.h>
8#include <uapi/linux/time.h>
9#include <uapi/linux/types.h>
10#include <uapi/asm-generic/errno-base.h>
11
12#include <vdso/bits.h>
13#include <vdso/clocksource.h>
14#include <vdso/ktime.h>
15#include <vdso/limits.h>
16#include <vdso/math64.h>
17#include <vdso/processor.h>
18#include <vdso/time.h>
19#include <vdso/time32.h>
20#include <vdso/time64.h>
21
22#ifdef CONFIG_ARCH_HAS_VDSO_DATA
23#include <asm/vdso/data.h>
24#else
25struct arch_vdso_data {};
26#endif
27
28#define VDSO_BASES	(CLOCK_TAI + 1)
29#define VDSO_HRES	(BIT(CLOCK_REALTIME)		| \
30			 BIT(CLOCK_MONOTONIC)		| \
31			 BIT(CLOCK_BOOTTIME)		| \
32			 BIT(CLOCK_TAI))
33#define VDSO_COARSE	(BIT(CLOCK_REALTIME_COARSE)	| \
34			 BIT(CLOCK_MONOTONIC_COARSE))
35#define VDSO_RAW	(BIT(CLOCK_MONOTONIC_RAW))
36
37#define CS_HRES_COARSE	0
38#define CS_RAW		1
39#define CS_BASES	(CS_RAW + 1)
40
41/**
42 * struct vdso_timestamp - basetime per clock_id
43 * @sec:	seconds
44 * @nsec:	nanoseconds
45 *
46 * There is one vdso_timestamp object in vvar for each vDSO-accelerated
47 * clock_id. For high-resolution clocks, this encodes the time
48 * corresponding to vdso_data.cycle_last. For coarse clocks this encodes
49 * the actual time.
50 *
51 * To be noticed that for highres clocks nsec is left-shifted by
52 * vdso_data.cs[x].shift.
53 */
54struct vdso_timestamp {
55	u64	sec;
56	u64	nsec;
57};
58
59/**
60 * struct vdso_data - vdso datapage representation
61 * @seq:		timebase sequence counter
62 * @clock_mode:		clock mode
63 * @cycle_last:		timebase at clocksource init
64 * @mask:		clocksource mask
65 * @mult:		clocksource multiplier
66 * @shift:		clocksource shift
67 * @basetime[clock_id]:	basetime per clock_id
68 * @offset[clock_id]:	time namespace offset per clock_id
69 * @tz_minuteswest:	minutes west of Greenwich
70 * @tz_dsttime:		type of DST correction
71 * @hrtimer_res:	hrtimer resolution
72 * @__unused:		unused
73 * @arch_data:		architecture specific data (optional, defaults
74 *			to an empty struct)
75 *
76 * vdso_data will be accessed by 64 bit and compat code at the same time
77 * so we should be careful before modifying this structure.
78 *
79 * @basetime is used to store the base time for the system wide time getter
80 * VVAR page.
81 *
82 * @offset is used by the special time namespace VVAR pages which are
83 * installed instead of the real VVAR page. These namespace pages must set
84 * @seq to 1 and @clock_mode to VDSO_CLOCKMODE_TIMENS to force the code into
85 * the time namespace slow path. The namespace aware functions retrieve the
86 * real system wide VVAR page, read host time and add the per clock offset.
87 * For clocks which are not affected by time namespace adjustment the
88 * offset must be zero.
89 */
90struct vdso_data {
91	u32			seq;
92
93	s32			clock_mode;
94	u64			cycle_last;
95	u64			mask;
96	u32			mult;
97	u32			shift;
98
99	union {
100		struct vdso_timestamp	basetime[VDSO_BASES];
101		struct timens_offset	offset[VDSO_BASES];
102	};
103
104	s32			tz_minuteswest;
105	s32			tz_dsttime;
106	u32			hrtimer_res;
107	u32			__unused;
108
109	struct arch_vdso_data	arch_data;
110};
111
112/*
113 * We use the hidden visibility to prevent the compiler from generating a GOT
114 * relocation. Not only is going through a GOT useless (the entry couldn't and
115 * must not be overridden by another library), it does not even work: the linker
116 * cannot generate an absolute address to the data page.
117 *
118 * With the hidden visibility, the compiler simply generates a PC-relative
119 * relocation, and this is what we need.
120 */
121extern struct vdso_data _vdso_data[CS_BASES] __attribute__((visibility("hidden")));
122extern struct vdso_data _timens_data[CS_BASES] __attribute__((visibility("hidden")));
123
124/**
125 * union vdso_data_store - Generic vDSO data page
126 */
127union vdso_data_store {
128	struct vdso_data	data[CS_BASES];
129	u8			page[1U << CONFIG_PAGE_SHIFT];
130};
131
132/*
133 * The generic vDSO implementation requires that gettimeofday.h
134 * provides:
135 * - __arch_get_vdso_data(): to get the vdso datapage.
136 * - __arch_get_hw_counter(): to get the hw counter based on the
137 *   clock_mode.
138 * - gettimeofday_fallback(): fallback for gettimeofday.
139 * - clock_gettime_fallback(): fallback for clock_gettime.
140 * - clock_getres_fallback(): fallback for clock_getres.
141 */
142#ifdef ENABLE_COMPAT_VDSO
143#include <asm/vdso/compat_gettimeofday.h>
144#else
145#include <asm/vdso/gettimeofday.h>
146#endif /* ENABLE_COMPAT_VDSO */
147
148#endif /* !__ASSEMBLY__ */
149
150#endif /* __VDSO_DATAPAGE_H */
151