From: Robin Murphy <robin.murphy@arm.com> To: will@kernel.org, mark.rutland@arm.com Cc: linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org Subject: [PATCH] perf/smmuv3: Don't trample existing events with global filter Date: Tue, 8 Jun 2021 12:55:12 +0100 [thread overview] Message-ID: <32c80c0e46237f49ad8da0c9f8864e13c4a803aa.1623153312.git.robin.murphy@arm.com> (raw) With global filtering, we only allow an event to be scheduled if its filter settings exactly match those of any existing events, therefore it is pointless to reapply the filter in that case. Much worse, though, is that in doing that we trample the event type of counter 0 if it's already active, and never touch the appropriate PMEVTYPERn so the new event is likely not counting the right thing either. Don't do that. CC: stable@vger.kernel.org Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- drivers/perf/arm_smmuv3_pmu.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c index ff6fab4bae30..863d9f702aa1 100644 --- a/drivers/perf/arm_smmuv3_pmu.c +++ b/drivers/perf/arm_smmuv3_pmu.c @@ -277,7 +277,7 @@ static int smmu_pmu_apply_event_filter(struct smmu_pmu *smmu_pmu, struct perf_event *event, int idx) { u32 span, sid; - unsigned int num_ctrs = smmu_pmu->num_counters; + unsigned int cur_idx, num_ctrs = smmu_pmu->num_counters; bool filter_en = !!get_filter_enable(event); span = filter_en ? get_filter_span(event) : @@ -285,17 +285,19 @@ static int smmu_pmu_apply_event_filter(struct smmu_pmu *smmu_pmu, sid = filter_en ? get_filter_stream_id(event) : SMMU_PMCG_DEFAULT_FILTER_SID; - /* Support individual filter settings */ - if (!smmu_pmu->global_filter) { + cur_idx = find_first_bit(smmu_pmu->used_counters, num_ctrs); + /* + * Per-counter filtering, or scheduling the first globally-filtered + * event into an empty PMU so idx == 0 and it works out equivalent. + */ + if (!smmu_pmu->global_filter || cur_idx == num_ctrs) { smmu_pmu_set_event_filter(event, idx, span, sid); return 0; } - /* Requested settings same as current global settings*/ - idx = find_first_bit(smmu_pmu->used_counters, num_ctrs); - if (idx == num_ctrs || - smmu_pmu_check_global_filter(smmu_pmu->events[idx], event)) { - smmu_pmu_set_event_filter(event, 0, span, sid); + /* Otherwise, must match whatever's currently scheduled */ + if (smmu_pmu_check_global_filter(smmu_pmu->events[cur_idx], event)) { + smmu_pmu_set_evtyper(smmu_pmu, idx, get_event(event)); return 0; } -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Robin Murphy <robin.murphy@arm.com> To: will@kernel.org, mark.rutland@arm.com Cc: linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org Subject: [PATCH] perf/smmuv3: Don't trample existing events with global filter Date: Tue, 8 Jun 2021 12:55:12 +0100 [thread overview] Message-ID: <32c80c0e46237f49ad8da0c9f8864e13c4a803aa.1623153312.git.robin.murphy@arm.com> (raw) With global filtering, we only allow an event to be scheduled if its filter settings exactly match those of any existing events, therefore it is pointless to reapply the filter in that case. Much worse, though, is that in doing that we trample the event type of counter 0 if it's already active, and never touch the appropriate PMEVTYPERn so the new event is likely not counting the right thing either. Don't do that. CC: stable@vger.kernel.org Signed-off-by: Robin Murphy <robin.murphy@arm.com> --- drivers/perf/arm_smmuv3_pmu.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c index ff6fab4bae30..863d9f702aa1 100644 --- a/drivers/perf/arm_smmuv3_pmu.c +++ b/drivers/perf/arm_smmuv3_pmu.c @@ -277,7 +277,7 @@ static int smmu_pmu_apply_event_filter(struct smmu_pmu *smmu_pmu, struct perf_event *event, int idx) { u32 span, sid; - unsigned int num_ctrs = smmu_pmu->num_counters; + unsigned int cur_idx, num_ctrs = smmu_pmu->num_counters; bool filter_en = !!get_filter_enable(event); span = filter_en ? get_filter_span(event) : @@ -285,17 +285,19 @@ static int smmu_pmu_apply_event_filter(struct smmu_pmu *smmu_pmu, sid = filter_en ? get_filter_stream_id(event) : SMMU_PMCG_DEFAULT_FILTER_SID; - /* Support individual filter settings */ - if (!smmu_pmu->global_filter) { + cur_idx = find_first_bit(smmu_pmu->used_counters, num_ctrs); + /* + * Per-counter filtering, or scheduling the first globally-filtered + * event into an empty PMU so idx == 0 and it works out equivalent. + */ + if (!smmu_pmu->global_filter || cur_idx == num_ctrs) { smmu_pmu_set_event_filter(event, idx, span, sid); return 0; } - /* Requested settings same as current global settings*/ - idx = find_first_bit(smmu_pmu->used_counters, num_ctrs); - if (idx == num_ctrs || - smmu_pmu_check_global_filter(smmu_pmu->events[idx], event)) { - smmu_pmu_set_event_filter(event, 0, span, sid); + /* Otherwise, must match whatever's currently scheduled */ + if (smmu_pmu_check_global_filter(smmu_pmu->events[cur_idx], event)) { + smmu_pmu_set_evtyper(smmu_pmu, idx, get_event(event)); return 0; } -- 2.25.1 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2021-06-08 11:55 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-08 11:55 Robin Murphy [this message] 2021-06-08 11:55 ` [PATCH] perf/smmuv3: Don't trample existing events with global filter Robin Murphy 2021-06-11 16:15 ` Will Deacon 2021-06-11 16:15 ` Will Deacon
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