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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef __VDSO_DATAPAGE_H
3#define __VDSO_DATAPAGE_H
4
5#ifndef __ASSEMBLER__
6
7#include <linux/types.h>
8
9#include <uapi/linux/bits.h>
10#include <uapi/linux/time.h>
11
12#include <vdso/align.h>
13#include <vdso/bits.h>
14#include <vdso/cache.h>
15#include <vdso/page.h>
16#include <vdso/time.h>
17
18#ifdef CONFIG_ARCH_HAS_VDSO_TIME_DATA
19#include <asm/vdso/time_data.h>
20#else
21struct arch_vdso_time_data {};
22#endif
23
24#if defined(CONFIG_ARCH_HAS_VDSO_ARCH_DATA)
25#include <asm/vdso/arch_data.h>
26#else
27struct vdso_arch_data {
28 /* Needed for the generic code, never actually used at runtime */
29 char __unused;
30};
31#endif
32
33#define VDSO_BASES (CLOCK_TAI + 1)
34#define VDSO_BASE_AUX 0
35#define VDSO_HRES (BIT(CLOCK_REALTIME) | \
36 BIT(CLOCK_MONOTONIC) | \
37 BIT(CLOCK_BOOTTIME) | \
38 BIT(CLOCK_TAI))
39#define VDSO_COARSE (BIT(CLOCK_REALTIME_COARSE) | \
40 BIT(CLOCK_MONOTONIC_COARSE))
41#define VDSO_RAW (BIT(CLOCK_MONOTONIC_RAW))
42#define VDSO_AUX __GENMASK(CLOCK_AUX_LAST, CLOCK_AUX)
43
44#define CS_HRES_COARSE 0
45#define CS_RAW 1
46#define CS_BASES (CS_RAW + 1)
47
48/**
49 * struct vdso_timestamp - basetime per clock_id
50 * @sec: seconds
51 * @nsec: nanoseconds
52 *
53 * There is one vdso_timestamp object in vvar for each vDSO-accelerated
54 * clock_id. For high-resolution clocks, this encodes the time
55 * corresponding to vdso_time_data.cycle_last. For coarse clocks this encodes
56 * the actual time.
57 *
58 * To be noticed that for highres clocks nsec is left-shifted by
59 * vdso_time_data[x].shift.
60 */
61struct vdso_timestamp {
62 u64 sec;
63 u64 nsec;
64};
65
66/**
67 * struct vdso_clock - vdso per clocksource datapage representation
68 * @seq: timebase sequence counter
69 * @clock_mode: clock mode
70 * @cycle_last: timebase at clocksource init
71 * @max_cycles: maximum cycles which won't overflow 64bit multiplication
72 * @mask: clocksource mask
73 * @mult: clocksource multiplier
74 * @shift: clocksource shift
75 * @basetime: basetime per clock_id
76 * @offset: time namespace offset per clock_id
77 *
78 * See also struct vdso_time_data for basic access and ordering information as
79 * struct vdso_clock is used there.
80 *
81 * @basetime is used to store the base time for the system wide time getter
82 * VVAR page.
83 *
84 * @offset is used by the special time namespace VVAR pages which are
85 * installed instead of the real VVAR page. These namespace pages must set
86 * @seq to 1 and @clock_mode to VDSO_CLOCKMODE_TIMENS to force the code into
87 * the time namespace slow path. The namespace aware functions retrieve the
88 * real system wide VVAR page, read host time and add the per clock offset.
89 * For clocks which are not affected by time namespace adjustment the
90 * offset must be zero.
91 */
92struct vdso_clock {
93 u32 seq;
94
95 s32 clock_mode;
96 u64 cycle_last;
97#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
98 u64 max_cycles;
99#endif
100 u64 mask;
101 u32 mult;
102 u32 shift;
103
104 union {
105 struct vdso_timestamp basetime[VDSO_BASES];
106 struct timens_offset offset[VDSO_BASES];
107 };
108};
109
110/**
111 * struct vdso_time_data - vdso datapage representation
112 * @arch_data: architecture specific data (optional, defaults
113 * to an empty struct)
114 * @clock_data: clocksource related data (array)
115 * @aux_clock_data: auxiliary clocksource related data (array)
116 * @tz_minuteswest: minutes west of Greenwich
117 * @tz_dsttime: type of DST correction
118 * @hrtimer_res: hrtimer resolution
119 * @__unused: unused
120 *
121 * vdso_time_data will be accessed by 64 bit and compat code at the same time
122 * so we should be careful before modifying this structure.
123 *
124 * The ordering of the struct members is optimized to have fast acces to the
125 * often required struct members which are related to CLOCK_REALTIME and
126 * CLOCK_MONOTONIC. This information is stored in the first cache lines.
127 */
128struct vdso_time_data {
129 struct arch_vdso_time_data arch_data;
130
131 struct vdso_clock clock_data[CS_BASES];
132 struct vdso_clock aux_clock_data[MAX_AUX_CLOCKS];
133
134 s32 tz_minuteswest;
135 s32 tz_dsttime;
136 u32 hrtimer_res;
137 u32 __unused;
138} ____cacheline_aligned;
139
140/**
141 * struct vdso_rng_data - vdso RNG state information
142 * @generation: counter representing the number of RNG reseeds
143 * @is_ready: boolean signaling whether the RNG is initialized
144 */
145struct vdso_rng_data {
146 u64 generation;
147 u8 is_ready;
148};
149
150/*
151 * We use the hidden visibility to prevent the compiler from generating a GOT
152 * relocation. Not only is going through a GOT useless (the entry couldn't and
153 * must not be overridden by another library), it does not even work: the linker
154 * cannot generate an absolute address to the data page.
155 *
156 * With the hidden visibility, the compiler simply generates a PC-relative
157 * relocation, and this is what we need.
158 */
159extern struct vdso_time_data vdso_u_time_data __attribute__((visibility("hidden")));
160extern struct vdso_rng_data vdso_u_rng_data __attribute__((visibility("hidden")));
161extern struct vdso_arch_data vdso_u_arch_data __attribute__((visibility("hidden")));
162
163extern struct vdso_time_data *vdso_k_time_data;
164extern struct vdso_rng_data *vdso_k_rng_data;
165extern struct vdso_arch_data *vdso_k_arch_data;
166
167#define VDSO_ARCH_DATA_SIZE ALIGN(sizeof(struct vdso_arch_data), PAGE_SIZE)
168#define VDSO_ARCH_DATA_PAGES (VDSO_ARCH_DATA_SIZE >> PAGE_SHIFT)
169
170enum vdso_pages {
171 VDSO_TIME_PAGE_OFFSET,
172 VDSO_TIMENS_PAGE_OFFSET,
173 VDSO_RNG_PAGE_OFFSET,
174 VDSO_ARCH_PAGES_START,
175 VDSO_ARCH_PAGES_END = VDSO_ARCH_PAGES_START + VDSO_ARCH_DATA_PAGES - 1,
176 VDSO_NR_PAGES
177};
178
179#else /* !__ASSEMBLER__ */
180
181#ifdef CONFIG_VDSO_GETRANDOM
182#define __vdso_u_rng_data PROVIDE(vdso_u_rng_data = vdso_u_data + 2 * PAGE_SIZE);
183#else
184#define __vdso_u_rng_data
185#endif
186
187#ifdef CONFIG_ARCH_HAS_VDSO_ARCH_DATA
188#define __vdso_u_arch_data PROVIDE(vdso_u_arch_data = vdso_u_data + 3 * PAGE_SIZE);
189#else
190#define __vdso_u_arch_data
191#endif
192
193#define VDSO_VVAR_SYMS \
194 PROVIDE(vdso_u_data = . - __VDSO_PAGES * PAGE_SIZE); \
195 PROVIDE(vdso_u_time_data = vdso_u_data); \
196 __vdso_u_rng_data \
197 __vdso_u_arch_data \
198
199
200#endif /* !__ASSEMBLER__ */
201
202#endif /* __VDSO_DATAPAGE_H */