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>
23 #include <asm/page-def.h>
28 #ifdef CONFIG_ARCH_HAS_VDSO_DATA
29 #include <asm/vdso/data.h>
31 struct arch_vdso_data {};
34 #define VDSO_BASES (CLOCK_TAI + 1)
35 #define VDSO_HRES (BIT(CLOCK_REALTIME) | \
36 BIT(CLOCK_MONOTONIC) | \
37 BIT(CLOCK_BOOTTIME) | \
39 #define VDSO_COARSE (BIT(CLOCK_REALTIME_COARSE) | \
40 BIT(CLOCK_MONOTONIC_COARSE))
41 #define VDSO_RAW (BIT(CLOCK_MONOTONIC_RAW))
43 #define CS_HRES_COARSE 0
45 #define CS_BASES (CS_RAW + 1)
48 * struct vdso_timestamp - basetime per clock_id
52 * There is one vdso_timestamp object in vvar for each vDSO-accelerated
53 * clock_id. For high-resolution clocks, this encodes the time
54 * corresponding to vdso_data.cycle_last. For coarse clocks this encodes
57 * To be noticed that for highres clocks nsec is left-shifted by
58 * vdso_data.cs[x].shift.
60 struct vdso_timestamp {
66 * struct vdso_data - vdso datapage representation
67 * @seq: timebase sequence counter
68 * @clock_mode: clock mode
69 * @cycle_last: timebase at clocksource init
70 * @mask: clocksource mask
71 * @mult: clocksource multiplier
72 * @shift: clocksource shift
73 * @basetime[clock_id]: basetime per clock_id
74 * @offset[clock_id]: time namespace offset per clock_id
75 * @tz_minuteswest: minutes west of Greenwich
76 * @tz_dsttime: type of DST correction
77 * @hrtimer_res: hrtimer resolution
79 * @arch_data: architecture specific data (optional, defaults
82 * vdso_data will be accessed by 64 bit and compat code at the same time
83 * so we should be careful before modifying this structure.
85 * @basetime is used to store the base time for the system wide time getter
88 * @offset is used by the special time namespace VVAR pages which are
89 * installed instead of the real VVAR page. These namespace pages must set
90 * @seq to 1 and @clock_mode to VDSO_CLOCKMODE_TIMENS to force the code into
91 * the time namespace slow path. The namespace aware functions retrieve the
92 * real system wide VVAR page, read host time and add the per clock offset.
93 * For clocks which are not affected by time namespace adjustment the
94 * offset must be zero.
106 struct vdso_timestamp basetime[VDSO_BASES];
107 struct timens_offset offset[VDSO_BASES];
115 struct arch_vdso_data arch_data;
119 * We use the hidden visibility to prevent the compiler from generating a GOT
120 * relocation. Not only is going through a GOT useless (the entry couldn't and
121 * must not be overridden by another library), it does not even work: the linker
122 * cannot generate an absolute address to the data page.
124 * With the hidden visibility, the compiler simply generates a PC-relative
125 * relocation, and this is what we need.
127 extern struct vdso_data _vdso_data[CS_BASES] __attribute__((visibility("hidden")));
128 extern struct vdso_data _timens_data[CS_BASES] __attribute__((visibility("hidden")));
131 * union vdso_data_store - Generic vDSO data page
133 union vdso_data_store {
134 struct vdso_data data[CS_BASES];
139 * The generic vDSO implementation requires that gettimeofday.h
141 * - __arch_get_vdso_data(): to get the vdso datapage.
142 * - __arch_get_hw_counter(): to get the hw counter based on the
144 * - gettimeofday_fallback(): fallback for gettimeofday.
145 * - clock_gettime_fallback(): fallback for clock_gettime.
146 * - clock_getres_fallback(): fallback for clock_getres.
148 #ifdef ENABLE_COMPAT_VDSO
149 #include <asm/vdso/compat_gettimeofday.h>
151 #include <asm/vdso/gettimeofday.h>
152 #endif /* ENABLE_COMPAT_VDSO */
154 #endif /* !__ASSEMBLY__ */
156 #endif /* __VDSO_DATAPAGE_H */