On 01/03/2021 02:15, Michael Kelley wrote:
> While the Hyper-V Reference TSC code is architecture neutral, the
> pv_ops.time.sched_clock() function is implemented for x86/x64, but not
> for ARM64. Current code calls a utility function under arch/x86 (and
> coming, under arch/arm64) to handle the difference.
>
> Change this approach to handle the difference inline based on whether
> GENERIC_SCHED_CLOCK is present. The new approach removes code under
> arch/* since the difference is tied more to the specifics of the Linux
> implementation than to the architecture.
>
> No functional change.
>
> Signed-off-by: Michael Kelley <mikel...@microsoft.com>
> Reviewed-by: Boqun Feng <boqun.f...@gmail.com>
> ---
[ ... ]
> +/*
> + * Reference to pv_ops must be inline so objtool
> + * detection of noinstr violations can work correctly.
> + */
> +static __always_inline void hv_setup_sched_clock(void *sched_clock)
> +{
> +#ifdef CONFIG_GENERIC_SCHED_CLOCK
> + /*
> + * We're on an architecture with generic sched clock (not x86/x64).
> + * The Hyper-V sched clock read function returns nanoseconds, not
> + * the normal 100ns units of the Hyper-V synthetic clock.
> + */
> + sched_clock_register(sched_clock, 64, NSEC_PER_SEC);
> +#else
> +#ifdef CONFIG_PARAVIRT
> + /* We're on x86/x64 *and* using PV ops */
> + pv_ops.time.sched_clock = sched_clock;
> +#endif
> +#endif
> +}
Please refer to:
Documentation/process/coding-style.rst
Section 21)
[ ... ]
Prefer to compile out entire functions, rather than portions of
functions or portions of expressions.
[ ... ]
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