170 lines
5.0 KiB
C
170 lines
5.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __VDSO_DATAPAGE_H
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#define __VDSO_DATAPAGE_H
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#ifndef __ASSEMBLY__
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#include <linux/compiler.h>
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#include <uapi/linux/time.h>
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#include <uapi/linux/types.h>
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#include <uapi/asm-generic/errno-base.h>
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#include <vdso/bits.h>
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#include <vdso/clocksource.h>
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#include <vdso/ktime.h>
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#include <vdso/limits.h>
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#include <vdso/math64.h>
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#include <vdso/processor.h>
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#include <vdso/time.h>
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#include <vdso/time32.h>
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#include <vdso/time64.h>
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#ifdef CONFIG_ARCH_HAS_VDSO_DATA
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#include <asm/vdso/data.h>
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#else
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struct arch_vdso_data {};
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#endif
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#define VDSO_BASES (CLOCK_TAI + 1)
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#define VDSO_HRES (BIT(CLOCK_REALTIME) | \
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BIT(CLOCK_MONOTONIC) | \
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BIT(CLOCK_BOOTTIME) | \
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BIT(CLOCK_TAI))
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#define VDSO_COARSE (BIT(CLOCK_REALTIME_COARSE) | \
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BIT(CLOCK_MONOTONIC_COARSE))
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#define VDSO_RAW (BIT(CLOCK_MONOTONIC_RAW))
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#define CS_HRES_COARSE 0
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#define CS_RAW 1
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#define CS_BASES (CS_RAW + 1)
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/**
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* struct vdso_timestamp - basetime per clock_id
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* @sec: seconds
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* @nsec: nanoseconds
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*
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* There is one vdso_timestamp object in vvar for each vDSO-accelerated
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* clock_id. For high-resolution clocks, this encodes the time
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* corresponding to vdso_data.cycle_last. For coarse clocks this encodes
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* the actual time.
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*
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* To be noticed that for highres clocks nsec is left-shifted by
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* vdso_data.cs[x].shift.
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*/
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struct vdso_timestamp {
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u64 sec;
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u64 nsec;
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};
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/**
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* struct vdso_data - vdso datapage representation
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* @seq: timebase sequence counter
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* @clock_mode: clock mode
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* @cycle_last: timebase at clocksource init
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* @max_cycles: maximum cycles which won't overflow 64bit multiplication
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* @mask: clocksource mask
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* @mult: clocksource multiplier
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* @shift: clocksource shift
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* @basetime[clock_id]: basetime per clock_id
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* @offset[clock_id]: time namespace offset per clock_id
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* @tz_minuteswest: minutes west of Greenwich
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* @tz_dsttime: type of DST correction
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* @hrtimer_res: hrtimer resolution
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* @__unused: unused
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* @arch_data: architecture specific data (optional, defaults
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* to an empty struct)
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*
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* vdso_data will be accessed by 64 bit and compat code at the same time
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* so we should be careful before modifying this structure.
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*
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* The ordering of the struct members is optimized to have fast access to the
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* often required struct members which are related to CLOCK_REALTIME and
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* CLOCK_MONOTONIC. This information is stored in the first cache lines.
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*
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* @basetime is used to store the base time for the system wide time getter
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* VVAR page.
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*
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* @offset is used by the special time namespace VVAR pages which are
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* installed instead of the real VVAR page. These namespace pages must set
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* @seq to 1 and @clock_mode to VDSO_CLOCKMODE_TIMENS to force the code into
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* the time namespace slow path. The namespace aware functions retrieve the
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* real system wide VVAR page, read host time and add the per clock offset.
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* For clocks which are not affected by time namespace adjustment the
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* offset must be zero.
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*/
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struct vdso_data {
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u32 seq;
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s32 clock_mode;
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u64 cycle_last;
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#ifdef CONFIG_GENERIC_VDSO_OVERFLOW_PROTECT
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u64 max_cycles;
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#endif
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u64 mask;
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u32 mult;
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u32 shift;
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union {
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struct vdso_timestamp basetime[VDSO_BASES];
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struct timens_offset offset[VDSO_BASES];
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};
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s32 tz_minuteswest;
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s32 tz_dsttime;
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u32 hrtimer_res;
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u32 __unused;
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struct arch_vdso_data arch_data;
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};
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/**
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* struct vdso_rng_data - vdso RNG state information
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* @generation: counter representing the number of RNG reseeds
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* @is_ready: boolean signaling whether the RNG is initialized
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*/
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struct vdso_rng_data {
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u64 generation;
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u8 is_ready;
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};
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/*
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* We use the hidden visibility to prevent the compiler from generating a GOT
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* relocation. Not only is going through a GOT useless (the entry couldn't and
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* must not be overridden by another library), it does not even work: the linker
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* cannot generate an absolute address to the data page.
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*
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* With the hidden visibility, the compiler simply generates a PC-relative
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* relocation, and this is what we need.
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*/
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extern struct vdso_data _vdso_data[CS_BASES] __attribute__((visibility("hidden")));
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extern struct vdso_data _timens_data[CS_BASES] __attribute__((visibility("hidden")));
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extern struct vdso_rng_data _vdso_rng_data __attribute__((visibility("hidden")));
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/**
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* union vdso_data_store - Generic vDSO data page
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*/
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union vdso_data_store {
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struct vdso_data data[CS_BASES];
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u8 page[1U << CONFIG_PAGE_SHIFT];
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};
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/*
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* The generic vDSO implementation requires that gettimeofday.h
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* provides:
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* - __arch_get_vdso_data(): to get the vdso datapage.
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* - __arch_get_hw_counter(): to get the hw counter based on the
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* clock_mode.
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* - gettimeofday_fallback(): fallback for gettimeofday.
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* - clock_gettime_fallback(): fallback for clock_gettime.
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* - clock_getres_fallback(): fallback for clock_getres.
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*/
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#ifdef ENABLE_COMPAT_VDSO
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#include <asm/vdso/compat_gettimeofday.h>
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#else
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#include <asm/vdso/gettimeofday.h>
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#endif /* ENABLE_COMPAT_VDSO */
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#endif /* !__ASSEMBLY__ */
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#endif /* __VDSO_DATAPAGE_H */
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