Re: [PATCH v2 1/2] perf/core: out-of-line and export perf_allow_cpu/tracepoint()

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Fri, 22 May 2026 18:33:25 -0700, John Hubbard wrote:
>
> These helpers are static inline in <linux/perf_event.h> and reach
> into sysctl_perf_event_paranoid and security_perf_event_open(),
> neither of which is itself exported. The perf_allow_* trio is
> therefore asymmetric: built-in callers can use any of the three, but
> modular code can only call perf_allow_kernel().
>
> Move both bodies into kernel/events/core.c next to perf_allow_kernel()
> and export them with EXPORT_SYMBOL_GPL, following the shape of
> commit 5e9629d0ae97 ("drivers/perf: arm_spe: Use perf_allow_kernel()
> for permissions"). Existing in-tree callers live in built-in arch and
> tracing code, so the change is invisible to them.
>
> Provide !CONFIG_PERF_EVENTS stubs that fall back to perfmon_capable(),
> so the helpers stay callable when perf is compiled out.
>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>

Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>

> ---
>  include/linux/perf_event.h | 31 +++++++++++++++----------------
>  kernel/events/core.c       | 18 ++++++++++++++++++
>  2 files changed, 33 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index 48d851fbd8ea..5842552294c1 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -1791,22 +1791,8 @@ static inline int perf_is_paranoid(void)
>  }
>
>  extern int perf_allow_kernel(void);
> -
> -static inline int perf_allow_cpu(void)
> -{
> -	if (sysctl_perf_event_paranoid > 0 && !perfmon_capable())
> -		return -EACCES;
> -
> -	return security_perf_event_open(PERF_SECURITY_CPU);
> -}
> -
> -static inline int perf_allow_tracepoint(void)
> -{
> -	if (sysctl_perf_event_paranoid > -1 && !perfmon_capable())
> -		return -EPERM;
> -
> -	return security_perf_event_open(PERF_SECURITY_TRACEPOINT);
> -}
> +extern int perf_allow_cpu(void);
> +extern int perf_allow_tracepoint(void);
>
>  extern int perf_exclude_event(struct perf_event *event, struct pt_regs *regs);
>
> @@ -2023,6 +2009,19 @@ perf_event_pause(struct perf_event *event, bool reset)			{ return 0; }
>  static inline int
>  perf_exclude_event(struct perf_event *event, struct pt_regs *regs)	{ return 0; }
>
> +static inline int perf_allow_kernel(void)
> +{
> +	return perfmon_capable() ? 0 : -EACCES;
> +}
> +static inline int perf_allow_cpu(void)
> +{
> +	return perfmon_capable() ? 0 : -EACCES;
> +}
> +static inline int perf_allow_tracepoint(void)
> +{
> +	return perfmon_capable() ? 0 : -EPERM;
> +}
> +
>  #endif /* !CONFIG_PERF_EVENTS */
>
>  #if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 7935d5663944..cb13f3ad11a3 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -14731,6 +14731,24 @@ int perf_allow_kernel(void)
>  }
>  EXPORT_SYMBOL_GPL(perf_allow_kernel);
>
> +int perf_allow_cpu(void)
> +{
> +	if (sysctl_perf_event_paranoid > 0 && !perfmon_capable())
> +		return -EACCES;
> +
> +	return security_perf_event_open(PERF_SECURITY_CPU);
> +}
> +EXPORT_SYMBOL_GPL(perf_allow_cpu);
> +
> +int perf_allow_tracepoint(void)
> +{
> +	if (sysctl_perf_event_paranoid > -1 && !perfmon_capable())
> +		return -EPERM;
> +
> +	return security_perf_event_open(PERF_SECURITY_TRACEPOINT);
> +}
> +EXPORT_SYMBOL_GPL(perf_allow_tracepoint);
> +
>  /*
>   * Inherit an event from parent task to child task.
>   *
> --
> 2.54.0
>