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

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

On Thu, 02 Jul 2026 06:25:36 -0700, Rodrigo Vivi wrote:
>
> 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?

Sorry, Rodrigo, I should have recorded  Peter's ack, it is here:

https://lore.kernel.org/intel-xe/20260527163014.GI3102624@noisy.programming.kicks-ass.net/

>
> > >  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
> > >