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[24.155.109.49]) by smtp.googlemail.com with ESMTPSA id q81sm1032138oia.46.2020.10.01.07.01.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Oct 2020 07:01:19 -0700 (PDT) From: Rob Herring To: Will Deacon , Catalin Marinas , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Jiri Olsa Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Alexander Shishkin , Namhyung Kim , Raphael Gault , Mark Rutland , Jonathan Cameron , Ian Rogers , honnappa.nagarahalli@arm.com, Itaru Kitayama Subject: [PATCH v4 1/9] arm64: pmu: Add function implementation to update event index in userpage Date: Thu, 1 Oct 2020 09:01:08 -0500 Message-Id: <20201001140116.651970-2-robh@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20201001140116.651970-1-robh@kernel.org> References: <20201001140116.651970-1-robh@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Raphael Gault 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 Signed-off-by: Rob Herring --- arch/arm64/kernel/perf_event.c | 21 +++++++++++++++++++++ include/linux/perf/arm_pmu.h | 2 ++ 2 files changed, 23 insertions(+) diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index 462f9a9cc44b..e14f360a7883 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -818,6 +818,22 @@ static void armv8pmu_clear_event_idx(struct pmu_hw_events *cpuc, clear_bit(idx - 1, cpuc->used_mask); } +static int armv8pmu_access_event_idx(struct perf_event *event) +{ + if (!(event->hw.flags & ARMPMU_EL0_RD_CNTR)) + return 0; + + /* + * We remap the cycle counter index to 32 to + * match the offset applied to the rest of + * the counter indices. + */ + if (event->hw.idx == ARMV8_IDX_CYCLE_COUNTER) + return 32; + + return event->hw.idx; +} + /* * Add an event filter to a given event. */ @@ -914,6 +930,9 @@ static int __armv8_pmuv3_map_event(struct perf_event *event, if (armv8pmu_event_is_64bit(event)) event->hw.flags |= ARMPMU_EVT_64BIT; + if (!armv8pmu_event_is_chained(event)) + event->hw.flags |= ARMPMU_EL0_RD_CNTR; + /* Only expose micro/arch events supported by this PMU */ if ((hw_event_id > 0) && (hw_event_id < ARMV8_PMUV3_MAX_COMMON_EVENTS) && test_bit(hw_event_id, armpmu->pmceid_bitmap)) { @@ -1038,6 +1057,8 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu, char *name, cpu_pmu->set_event_filter = armv8pmu_set_event_filter; cpu_pmu->filter_match = armv8pmu_filter_match; + cpu_pmu->pmu.event_idx = armv8pmu_access_event_idx; + cpu_pmu->name = name; cpu_pmu->map_event = map_event; cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_EVENTS] = events ? diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index 5b616dde9a4c..74fbbbd29dc7 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -26,6 +26,8 @@ */ /* Event uses a 64bit counter */ #define ARMPMU_EVT_64BIT 1 +/* Allow access to hardware counter from userspace */ +#define ARMPMU_EL0_RD_CNTR 2 #define HW_OP_UNSUPPORTED 0xFFFF #define C(_x) PERF_COUNT_HW_CACHE_##_x -- 2.25.1