1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __VDSO_DATAPAGE_H
3 #define __VDSO_DATAPAGE_H
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>
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>
22 #define VDSO_BASES (CLOCK_TAI + 1)
23 #define VDSO_HRES (BIT(CLOCK_REALTIME) | \
24 BIT(CLOCK_MONOTONIC) | \
25 BIT(CLOCK_BOOTTIME) | \
27 #define VDSO_COARSE (BIT(CLOCK_REALTIME_COARSE) | \
28 BIT(CLOCK_MONOTONIC_COARSE))
29 #define VDSO_RAW (BIT(CLOCK_MONOTONIC_RAW))
31 #define CS_HRES_COARSE 0
33 #define CS_BASES (CS_RAW + 1)
36 * struct vdso_timestamp - basetime per clock_id
40 * There is one vdso_timestamp object in vvar for each vDSO-accelerated
41 * clock_id. For high-resolution clocks, this encodes the time
42 * corresponding to vdso_data.cycle_last. For coarse clocks this encodes
45 * To be noticed that for highres clocks nsec is left-shifted by
46 * vdso_data.cs[x].shift.
48 struct vdso_timestamp {
54 * struct vdso_data - vdso datapage representation
55 * @seq: timebase sequence counter
56 * @clock_mode: clock mode
57 * @cycle_last: timebase at clocksource init
58 * @mask: clocksource mask
59 * @mult: clocksource multiplier
60 * @shift: clocksource shift
61 * @basetime[clock_id]: basetime per clock_id
62 * @offset[clock_id]: time namespace offset per clock_id
63 * @tz_minuteswest: minutes west of Greenwich
64 * @tz_dsttime: type of DST correction
65 * @hrtimer_res: hrtimer resolution
68 * vdso_data will be accessed by 64 bit and compat code at the same time
69 * so we should be careful before modifying this structure.
71 * @basetime is used to store the base time for the system wide time getter
74 * @offset is used by the special time namespace VVAR pages which are
75 * installed instead of the real VVAR page. These namespace pages must set
76 * @seq to 1 and @clock_mode to VLOCK_TIMENS to force the code into the
77 * time namespace slow path. The namespace aware functions retrieve the
78 * real system wide VVAR page, read host time and add the per clock offset.
79 * For clocks which are not affected by time namespace adjustment the
80 * offset must be zero.
92 struct vdso_timestamp basetime[VDSO_BASES];
93 struct timens_offset offset[VDSO_BASES];
103 * We use the hidden visibility to prevent the compiler from generating a GOT
104 * relocation. Not only is going through a GOT useless (the entry couldn't and
105 * must not be overridden by another library), it does not even work: the linker
106 * cannot generate an absolute address to the data page.
108 * With the hidden visibility, the compiler simply generates a PC-relative
109 * relocation, and this is what we need.
111 extern struct vdso_data _vdso_data[CS_BASES] __attribute__((visibility("hidden")));
114 * The generic vDSO implementation requires that gettimeofday.h
116 * - __arch_get_vdso_data(): to get the vdso datapage.
117 * - __arch_get_hw_counter(): to get the hw counter based on the
119 * - gettimeofday_fallback(): fallback for gettimeofday.
120 * - clock_gettime_fallback(): fallback for clock_gettime.
121 * - clock_getres_fallback(): fallback for clock_getres.
123 #ifdef ENABLE_COMPAT_VDSO
124 #include <asm/vdso/compat_gettimeofday.h>
126 #include <asm/vdso/gettimeofday.h>
127 #endif /* ENABLE_COMPAT_VDSO */
129 #endif /* !__ASSEMBLY__ */
131 #endif /* __VDSO_DATAPAGE_H */