From: Raphael Gault <raphael.gault@arm.com> To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: mingo@redhat.com, peterz@infradead.org, catalin.marinas@arm.com, will.deacon@arm.com, acme@kernel.org, mark.rutland@arm.com, Raphael Gault <raphael.gault@arm.com> Subject: [PATCH 4/7] arm64: pmu: Add function implementation to update event index in userpage. Date: Tue, 11 Jun 2019 13:53:12 +0100 [thread overview] Message-ID: <20190611125315.18736-5-raphael.gault@arm.com> (raw) In-Reply-To: <20190611125315.18736-1-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> --- 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 348d12eec566..293e4c365a53 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -829,6 +829,22 @@ 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 indeces. + */ + if (event->hw.idx == ARMV8_IDX_CYCLE_COUNTER) + return 32; + + return event->hw.idx; +} + /* * Add an event filter to a given event. */ @@ -922,6 +938,8 @@ static int __armv8_pmuv3_map_event(struct perf_event *event, if (armv8pmu_event_is_64bit(event)) event->hw.flags |= ARMPMU_EVT_64BIT; + 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)) { @@ -1042,6 +1060,8 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu) 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; + return 0; } @@ -1220,6 +1240,7 @@ void arch_perf_update_userpage(struct perf_event *event, */ freq = arch_timer_get_rate(); userpg->cap_user_time = 1; + userpg->cap_user_rdpmc = !!(event->hw.flags & ARMPMU_EL0_RD_CNTR); clocks_calc_mult_shift(&userpg->time_mult, &shift, freq, NSEC_PER_SEC, 0); diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index 4641e850b204..3bef390c1069 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -30,6 +30,8 @@ */ /* 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 -- 2.17.1
WARNING: multiple messages have this Message-ID (diff)
From: Raphael Gault <raphael.gault@arm.com> To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: mark.rutland@arm.com, peterz@infradead.org, catalin.marinas@arm.com, will.deacon@arm.com, acme@kernel.org, Raphael Gault <raphael.gault@arm.com>, mingo@redhat.com Subject: [PATCH 4/7] arm64: pmu: Add function implementation to update event index in userpage. Date: Tue, 11 Jun 2019 13:53:12 +0100 [thread overview] Message-ID: <20190611125315.18736-5-raphael.gault@arm.com> (raw) In-Reply-To: <20190611125315.18736-1-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> --- 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 348d12eec566..293e4c365a53 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -829,6 +829,22 @@ 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 indeces. + */ + if (event->hw.idx == ARMV8_IDX_CYCLE_COUNTER) + return 32; + + return event->hw.idx; +} + /* * Add an event filter to a given event. */ @@ -922,6 +938,8 @@ static int __armv8_pmuv3_map_event(struct perf_event *event, if (armv8pmu_event_is_64bit(event)) event->hw.flags |= ARMPMU_EVT_64BIT; + 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)) { @@ -1042,6 +1060,8 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu) 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; + return 0; } @@ -1220,6 +1240,7 @@ void arch_perf_update_userpage(struct perf_event *event, */ freq = arch_timer_get_rate(); userpg->cap_user_time = 1; + userpg->cap_user_rdpmc = !!(event->hw.flags & ARMPMU_EL0_RD_CNTR); clocks_calc_mult_shift(&userpg->time_mult, &shift, freq, NSEC_PER_SEC, 0); diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index 4641e850b204..3bef390c1069 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -30,6 +30,8 @@ */ /* 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 -- 2.17.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-06-11 12:53 UTC|newest] Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-06-11 12:53 [PATCH 0/7] arm64: Enable access to pmu registers by user-space Raphael Gault 2019-06-11 12:53 ` Raphael Gault 2019-06-11 12:53 ` [PATCH 1/7] perf: arm64: Compile tests unconditionally Raphael Gault 2019-06-11 12:53 ` Raphael Gault 2019-06-11 14:09 ` Mark Rutland 2019-06-11 14:09 ` Mark Rutland 2019-06-11 14:23 ` Arnaldo Carvalho de Melo 2019-06-11 14:23 ` Arnaldo Carvalho de Melo 2019-06-11 17:01 ` Mark Rutland 2019-06-11 17:01 ` Mark Rutland 2019-06-22 6:34 ` [tip:perf/core] perf tests " tip-bot for Raphael Gault 2019-06-11 12:53 ` [PATCH 2/7] perf: arm64: Add test to check userspace access to hardware counters Raphael Gault 2019-06-11 12:53 ` Raphael Gault 2019-06-11 12:53 ` [PATCH 3/7] perf: arm64: Use rseq to test userspace access to pmu counters Raphael Gault 2019-06-11 12:53 ` Raphael Gault 2019-06-11 14:33 ` Arnaldo Carvalho de Melo 2019-06-11 14:33 ` Arnaldo Carvalho de Melo 2019-06-11 16:57 ` Mark Rutland 2019-06-11 16:57 ` Mark Rutland 2019-06-11 19:33 ` Mathieu Desnoyers 2019-06-11 19:33 ` Mathieu Desnoyers 2019-06-13 7:10 ` Raphael Gault 2019-06-13 7:10 ` Raphael Gault 2019-06-13 8:27 ` Mathieu Desnoyers 2019-06-13 8:27 ` Mathieu Desnoyers 2019-06-13 11:02 ` Raphael Gault 2019-06-13 11:02 ` Raphael Gault 2019-06-25 13:20 ` Raphael Gault 2019-06-25 13:20 ` Raphael Gault 2019-06-25 13:29 ` Raphael Gault 2019-06-25 13:29 ` Raphael Gault 2019-06-25 13:41 ` Will Deacon 2019-06-25 13:41 ` Will Deacon 2019-06-11 12:53 ` Raphael Gault [this message] 2019-06-11 12:53 ` [PATCH 4/7] arm64: pmu: Add function implementation to update event index in userpage Raphael Gault 2019-06-11 12:53 ` [PATCH 5/7] arm64: pmu: Add hook to handle pmu-related undefined instructions Raphael Gault 2019-06-11 12:53 ` Raphael Gault 2019-06-11 12:53 ` [PATCH 6/7] arm64: perf: Enable pmu counter direct access for perf event on armv8 Raphael Gault 2019-06-11 12:53 ` Raphael Gault 2019-06-11 12:53 ` [PATCH 7/7] Documentation: arm64: Document PMU counters access from userspace Raphael Gault 2019-06-11 12:53 ` Raphael Gault
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