From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E85A2C7EE24 for ; Mon, 5 Jun 2023 07:58:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231407AbjFEH6e (ORCPT ); Mon, 5 Jun 2023 03:58:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47246 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231719AbjFEH6Y (ORCPT ); Mon, 5 Jun 2023 03:58:24 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 2A644E9; Mon, 5 Jun 2023 00:58:22 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6A670D75; Mon, 5 Jun 2023 00:59:07 -0700 (PDT) Received: from FVFF77S0Q05N (unknown [10.57.24.244]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id ACF123F793; Mon, 5 Jun 2023 00:58:19 -0700 (PDT) Date: Mon, 5 Jun 2023 08:58:16 +0100 From: Mark Rutland To: Anshuman Khandual Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, will@kernel.org, catalin.marinas@arm.com, Mark Brown , James Clark , Rob Herring , Marc Zyngier , Suzuki Poulose , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , linux-perf-users@vger.kernel.org Subject: Re: [PATCH V11 03/10] arm64/perf: Add branch stack support in struct arm_pmu Message-ID: References: <20230531040428.501523-1-anshuman.khandual@arm.com> <20230531040428.501523-4-anshuman.khandual@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230531040428.501523-4-anshuman.khandual@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 31, 2023 at 09:34:21AM +0530, Anshuman Khandual wrote: > This updates 'struct arm_pmu' for branch stack sampling support later. This > adds a new 'features' element in the structure to track supported features, > and another 'private' element to encapsulate implementation attributes on a > given 'struct arm_pmu'. These updates here will help in tracking any branch > stack sampling support, which is being added later. This also adds a helper > arm_pmu_branch_stack_supported(). > > This also enables perf branch stack sampling event on all 'struct arm pmu', > supporting the feature but after removing the current gate that blocks such > events unconditionally in armpmu_event_init(). Instead a quick probe can be > initiated via arm_pmu_branch_stack_supported() to ascertain the support. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Mark Rutland > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Tested-by: James Clark > Signed-off-by: Anshuman Khandual > --- > drivers/perf/arm_pmu.c | 3 +-- > include/linux/perf/arm_pmu.h | 12 +++++++++++- > 2 files changed, 12 insertions(+), 3 deletions(-) > > diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c > index aada47e3b126..d4a4f2bd89a5 100644 > --- a/drivers/perf/arm_pmu.c > +++ b/drivers/perf/arm_pmu.c > @@ -510,8 +510,7 @@ static int armpmu_event_init(struct perf_event *event) > !cpumask_test_cpu(event->cpu, &armpmu->supported_cpus)) > return -ENOENT; > > - /* does not support taken branch sampling */ > - if (has_branch_stack(event)) > + if (has_branch_stack(event) && !arm_pmu_branch_stack_supported(armpmu)) > return -EOPNOTSUPP; > > return __hw_perf_event_init(event); > diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h > index f7fbd162ca4c..0da745eaf426 100644 > --- a/include/linux/perf/arm_pmu.h > +++ b/include/linux/perf/arm_pmu.h > @@ -102,7 +102,9 @@ struct arm_pmu { > int (*map_event)(struct perf_event *event); > void (*sched_task)(struct perf_event_pmu_context *pmu_ctx, bool sched_in); > int num_events; > - bool secure_access; /* 32-bit ARM only */ > + unsigned int secure_access : 1, /* 32-bit ARM only */ > + has_branch_stack: 1, /* 64-bit ARM only */ > + reserved : 30; > #define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40 > DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS); > #define ARMV8_PMUV3_EXT_COMMON_EVENT_BASE 0x4000 > @@ -118,8 +120,16 @@ struct arm_pmu { > > /* Only to be used by ACPI probing code */ > unsigned long acpi_cpuid; > + > + /* Implementation specific attributes */ > + void *private; > }; > > +static inline bool arm_pmu_branch_stack_supported(struct arm_pmu *armpmu) > +{ > + return armpmu->has_branch_stack; > +} Since this is a trivial test, and we already access the 'secure_access' field directly, I'd prefer we removed this helper and directly accessesed arm_pmu::has_branch_stack, e.g. with the logic in armpmu_event_init() being: if (has_branch_stack(event) && !armpmu->has_branch_stack) return -EOPNOTSUPP; With that: Acked-by: Mark Rutland Mark.