datapage.h

  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 */