ac84bac406
While the explanation for time namespace <-> vdso interactions is very helpful it uses the wrong name in the comment when describing the clock mode making grepping a bit annoying. This seems like an accidental oversight when moving from VCLOCK_TIMENS to VDSO_CLOCKMODE_TIMENS. It seems that660fd04f93("lib/vdso: Prepare for time namespace support") misspelled VCLOCK_TIMENS as VLOCK_TIMENS which explains why it got missed when VCLOCK_TIMENS became VDSO_CLOCKMODE_TIMENS in2d6b01bd88("lib/vdso: Move VCLOCK_TIMENS to vdso_clock_modes"). Update the comment to use VDSO_CLOCKMODE_TIMENS. Fixes:660fd04f93("lib/vdso: Prepare for time namespace support") Fixes:2d6b01bd88("lib/vdso: Move VCLOCK_TIMENS to vdso_clock_modes") Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Andrei Vagin <avagin@gmail.com> Acked-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Link: https://lkml.kernel.org/r/20200420100615.1549804-1-christian.brauner@ubuntu.com
132 lines
3.8 KiB
C
132 lines
3.8 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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#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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* @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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*
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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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* @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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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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};
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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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/*
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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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