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/bits.h>
9#include <uapi/linux/time.h>
10#include <uapi/linux/types.h>
11#include <uapi/asm-generic/errno-base.h>
12
13#include <vdso/align.h>
14#include <vdso/bits.h>
15#include <vdso/cache.h>
16#include <vdso/clocksource.h>
17#include <vdso/ktime.h>
18#include <vdso/limits.h>
19#include <vdso/math64.h>
20#include <vdso/page.h>
21#include <vdso/processor.h>
22#include <vdso/time.h>
23#include <vdso/time32.h>
24#include <vdso/time64.h>
25
26#ifdef CONFIG_ARCH_HAS_VDSO_TIME_DATA
27#include <asm/vdso/time_data.h>
28#else
29struct arch_vdso_time_data {};
30#endif
31
32#if defined(CONFIG_ARCH_HAS_VDSO_ARCH_DATA)
33#include <asm/vdso/arch_data.h>
34#else
35struct vdso_arch_data {
36 /* Needed for the generic code, never actually used at runtime */
37 char __unused;
38};
39#endif
40
41#define VDSO_BASES (CLOCK_TAI + 1)
42#define VDSO_BASE_AUX 0
43#define VDSO_HRES (BIT(CLOCK_REALTIME) | \
44 BIT(CLOCK_MONOTONIC) | \
45 BIT(CLOCK_BOOTTIME) | \
46 BIT(CLOCK_TAI))
47#define VDSO_COARSE (BIT(CLOCK_REALTIME_COARSE) | \
48 BIT(CLOCK_MONOTONIC_COARSE))
49#define VDSO_RAW (BIT(CLOCK_MONOTONIC_RAW))
50#define VDSO_AUX __GENMASK(CLOCK_AUX_LAST, CLOCK_AUX)
51
52#define CS_HRES_COARSE 0
53#define CS_RAW 1
54#define CS_BASES (CS_RAW + 1)
55
56/**
57 * struct vdso_timestamp - basetime per clock_id
58 * @sec: seconds
59 * @nsec: nanoseconds
60 *
61 * There is one vdso_timestamp object in vvar for each vDSO-accelerated
62 * clock_id. For high-resolution clocks, this encodes the time
63 * corresponding to vdso_time_data.cycle_last. For coarse clocks this encodes
64 * the actual time.
65 *
66 * To be noticed that for highres clocks nsec is left-shifted by
67 * vdso_time_data[x].shift.
68 */
69struct vdso_timestamp {
70 u64 sec;
71 u64 nsec;
72};
73
74/**
75 * struct vdso_clock - vdso per clocksource datapage representation
76 * @seq: timebase sequence counter
77 * @clock_mode: clock mode
78 * @cycle_last: timebase at clocksource init
79 * @max_cycles: maximum cycles which won't overflow 64bit multiplication
80 * @mask: clocksource mask
81 * @mult: clocksource multiplier
82 * @shift: clocksource shift
83 * @basetime[clock_id]: basetime per clock_id
84 * @offset[clock_id]: time namespace offset per clock_id
85 *
86 * See also struct vdso_time_data for basic access and ordering information as
87 * struct vdso_clock is used there.
88 *
89 * @basetime is used to store the base time for the system wide time getter
90 * VVAR page.
91 *
92 * @offset is used by the special time namespace VVAR pages which are
93 * installed instead of the real VVAR page. These namespace pages must set
94 * @seq to 1 and @clock_mode to VDSO_CLOCKMODE_TIMENS to force the code into
95 * the time namespace slow path. The namespace aware functions retrieve the
96 * real system wide VVAR page, read host time and add the per clock offset.
97 * For clocks which are not affected by time namespace adjustment the
98 * offset must be zero.
99 */
100struct vdso_clock {
101 u32 seq;
102
103 s32 clock_mode;
104 u64 cycle_last;
105#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
106 u64 max_cycles;
107#endif
108 u64 mask;
109 u32 mult;
110 u32 shift;
111
112 union {
113 struct vdso_timestamp basetime[VDSO_BASES];
114 struct timens_offset offset[VDSO_BASES];
115 };
116};
117
118/**
119 * struct vdso_time_data - vdso datapage representation
120 * @arch_data: architecture specific data (optional, defaults
121 * to an empty struct)
122 * @clock_data: clocksource related data (array)
123 * @aux_clock_data: auxiliary clocksource related data (array)
124 * @tz_minuteswest: minutes west of Greenwich
125 * @tz_dsttime: type of DST correction
126 * @hrtimer_res: hrtimer resolution
127 * @__unused: unused
128 *
129 * vdso_time_data will be accessed by 64 bit and compat code at the same time
130 * so we should be careful before modifying this structure.
131 *
132 * The ordering of the struct members is optimized to have fast acces to the
133 * often required struct members which are related to CLOCK_REALTIME and
134 * CLOCK_MONOTONIC. This information is stored in the first cache lines.
135 */
136struct vdso_time_data {
137 struct arch_vdso_time_data arch_data;
138
139 struct vdso_clock clock_data[CS_BASES];
140 struct vdso_clock aux_clock_data[MAX_AUX_CLOCKS];
141
142 s32 tz_minuteswest;
143 s32 tz_dsttime;
144 u32 hrtimer_res;
145 u32 __unused;
146} ____cacheline_aligned;
147
148/**
149 * struct vdso_rng_data - vdso RNG state information
150 * @generation: counter representing the number of RNG reseeds
151 * @is_ready: boolean signaling whether the RNG is initialized
152 */
153struct vdso_rng_data {
154 u64 generation;
155 u8 is_ready;
156};
157
158/*
159 * We use the hidden visibility to prevent the compiler from generating a GOT
160 * relocation. Not only is going through a GOT useless (the entry couldn't and
161 * must not be overridden by another library), it does not even work: the linker
162 * cannot generate an absolute address to the data page.
163 *
164 * With the hidden visibility, the compiler simply generates a PC-relative
165 * relocation, and this is what we need.
166 */
167extern struct vdso_time_data vdso_u_time_data __attribute__((visibility("hidden")));
168extern struct vdso_rng_data vdso_u_rng_data __attribute__((visibility("hidden")));
169extern struct vdso_arch_data vdso_u_arch_data __attribute__((visibility("hidden")));
170
171extern struct vdso_time_data *vdso_k_time_data;
172extern struct vdso_rng_data *vdso_k_rng_data;
173extern struct vdso_arch_data *vdso_k_arch_data;
174
175#define VDSO_ARCH_DATA_SIZE ALIGN(sizeof(struct vdso_arch_data), PAGE_SIZE)
176#define VDSO_ARCH_DATA_PAGES (VDSO_ARCH_DATA_SIZE >> PAGE_SHIFT)
177
178enum vdso_pages {
179 VDSO_TIME_PAGE_OFFSET,
180 VDSO_TIMENS_PAGE_OFFSET,
181 VDSO_RNG_PAGE_OFFSET,
182 VDSO_ARCH_PAGES_START,
183 VDSO_ARCH_PAGES_END = VDSO_ARCH_PAGES_START + VDSO_ARCH_DATA_PAGES - 1,
184 VDSO_NR_PAGES
185};
186
187/*
188 * The generic vDSO implementation requires that gettimeofday.h
189 * provides:
190 * - __arch_get_hw_counter(): to get the hw counter based on the
191 * clock_mode.
192 * - gettimeofday_fallback(): fallback for gettimeofday.
193 * - clock_gettime_fallback(): fallback for clock_gettime.
194 * - clock_getres_fallback(): fallback for clock_getres.
195 */
196#include <asm/vdso/gettimeofday.h>
197
198#else /* !__ASSEMBLY__ */
199
200#ifdef CONFIG_VDSO_GETRANDOM
201#define __vdso_u_rng_data PROVIDE(vdso_u_rng_data = vdso_u_data + 2 * PAGE_SIZE);
202#else
203#define __vdso_u_rng_data
204#endif
205
206#ifdef CONFIG_ARCH_HAS_VDSO_ARCH_DATA
207#define __vdso_u_arch_data PROVIDE(vdso_u_arch_data = vdso_u_data + 3 * PAGE_SIZE);
208#else
209#define __vdso_u_arch_data
210#endif
211
212#define VDSO_VVAR_SYMS \
213 PROVIDE(vdso_u_data = . - __VDSO_PAGES * PAGE_SIZE); \
214 PROVIDE(vdso_u_time_data = vdso_u_data); \
215 __vdso_u_rng_data \
216 __vdso_u_arch_data \
217
218
219#endif /* !__ASSEMBLY__ */
220
221#endif /* __VDSO_DATAPAGE_H */
222

source code of linux/include/vdso/datapage.h