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

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, May 26, 2026 at 08:34:14PM -0700, Dixit, Ashutosh wrote:
> 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 ++++++++++++++++++

Peter, Ingo or any other perf maintainer, ack on this patch and on
propagating this through drm trees?

Thanks,
Rodrigo.

> >  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
> >