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 18F59C77B73 for ; Tue, 6 Jun 2023 04:47:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231947AbjFFEre (ORCPT ); Tue, 6 Jun 2023 00:47:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36214 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229536AbjFFErd (ORCPT ); Tue, 6 Jun 2023 00:47:33 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 43F10109; Mon, 5 Jun 2023 21:47:32 -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 899ABAB6; Mon, 5 Jun 2023 21:48:17 -0700 (PDT) Received: from [10.163.44.58] (unknown [10.163.44.58]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id AD7093F587; Mon, 5 Jun 2023 21:47:24 -0700 (PDT) Message-ID: <1a8965ed-1210-2350-1c97-aebc27d005b7@arm.com> Date: Tue, 6 Jun 2023 10:17:20 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH V11 03/10] arm64/perf: Add branch stack support in struct arm_pmu Content-Language: en-US To: Mark Rutland 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 References: <20230531040428.501523-1-anshuman.khandual@arm.com> <20230531040428.501523-4-anshuman.khandual@arm.com> From: Anshuman Khandual In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On 6/5/23 13:28, Mark Rutland wrote: > 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; Sure, will drop the helper and change as suggested in all the call sites. > > With that: > > Acked-by: Mark Rutland > > Mark.