sched_clock: Expose struct clock_read_data

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In order to support perf_event_mmap_page::cap_time features, an
architecture needs, aside from a userspace readable counter register,
to expose the exact clock data so that userspace can convert the
counter register into a correct timestamp.

Provide struct clock_read_data and two (seqcount) helpers so that
architectures (arm64 in specific) can expose the numbers to userspace.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Link: https://lore.kernel.org/r/20200716051130.4359-2-leo.yan@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>

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Peter Zijlstra 2020-07-16 13:11:24 +08:00 • committed by Will Deacon

parent 539707caa1

commit 1b86abc1c6

2 changed files with 41 additions and 28 deletions

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28

include/linux/sched_clock.h

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41

kernel/time/sched_clock.c

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