Messages in this thread | | | Date | Tue, 30 Mar 2021 16:30:37 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v6 01/10] arm64: pmu: Add function implementation to update event index in userpage |
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On Wed, Mar 10, 2021 at 05:08:28PM -0700, Rob Herring wrote: > From: Raphael Gault <raphael.gault@arm.com> > > In order to be able to access the counter directly for userspace, > we need to provide the index of the counter using the userpage. > We thus need to override the event_idx function to retrieve and > convert the perf_event index to armv8 hardware index. > > Since the arm_pmu driver can be used by any implementation, even > if not armv8, two components play a role into making sure the > behaviour is correct and consistent with the PMU capabilities: > > * the ARMPMU_EL0_RD_CNTR flag which denotes the capability to access > counter from userspace. > * the event_idx call back, which is implemented and initialized by > the PMU implementation: if no callback is provided, the default > behaviour applies, returning 0 as index value. > > Signed-off-by: Raphael Gault <raphael.gault@arm.com> > Signed-off-by: Rob Herring <robh@kernel.org> > --- > arch/arm64/kernel/perf_event.c | 18 ++++++++++++++++++ > include/linux/perf/arm_pmu.h | 2 ++ > 2 files changed, 20 insertions(+)
Acked-by: Will Deacon <will@kernel.org>
Will
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