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 D7A59C4332F for ; Tue, 19 Apr 2022 13:56:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343692AbiDSN7W (ORCPT ); Tue, 19 Apr 2022 09:59:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240005AbiDSN7N (ORCPT ); Tue, 19 Apr 2022 09:59:13 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 414AF38BEA; Tue, 19 Apr 2022 06:56:30 -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 047E31063; Tue, 19 Apr 2022 06:56:30 -0700 (PDT) Received: from [10.32.36.25] (e121896.Emea.Arm.com [10.32.36.25]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EC7023F766; Tue, 19 Apr 2022 06:56:26 -0700 (PDT) Message-ID: Date: Tue, 19 Apr 2022 14:56:25 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH V5 2/8] perf: Extend branch type classification Content-Language: en-US To: Anshuman Khandual , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, peterz@infradead.org, acme@kernel.org Cc: Robin Murphy , Suzuki Poulose , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Thomas Gleixner , Will Deacon , linux-arm-kernel@lists.infradead.org References: <20220404045046.634522-1-anshuman.khandual@arm.com> <20220404045046.634522-3-anshuman.khandual@arm.com> From: James Clark In-Reply-To: <20220404045046.634522-3-anshuman.khandual@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/04/2022 05:50, Anshuman Khandual wrote: > branch_entry.type now has ran out of space to accommodate more branch types > classification. This will prevent perf branch stack implementation on arm64 > (via BRBE) to capture all available branch types. Extending this bit field > i.e branch_entry.type [4 bits] is not an option as it will break user space > ABI both for little and big endian perf tools. > > Extend branch classification with a new field branch_entry.new_type via a > new branch type PERF_BR_EXTEND_ABI in branch_entry.type. Perf tools which > could decode PERF_BR_EXTEND_ABI, will then parse branch_entry.new_type as > well. > > branch_entry.new_type is a 4 bit field which can hold upto 16 branch types. > The first three branch types will hold various generic page faults followed > by five architecture specific branch types, which can be overridden by the > platform for specific use cases. These architecture specific branch types > gets overridden on arm64 platform for BRBE implementation. > > New generic branch types > > - PERF_BR_NEW_FAULT_ALGN > - PERF_BR_NEW_FAULT_DATA > - PERF_BR_NEW_FAULT_INST > > New arch specific branch types > > - PERF_BR_NEW_ARCH_1 > - PERF_BR_NEW_ARCH_2 > - PERF_BR_NEW_ARCH_3 > - PERF_BR_NEW_ARCH_4 > - PERF_BR_NEW_ARCH_5 > > Cc: Peter Zijlstra > Cc: Ingo Molnar > Cc: Arnaldo Carvalho de Melo > Cc: Mark Rutland > Cc: Alexander Shishkin > Cc: Jiri Olsa > Cc: Namhyung Kim > Cc: Thomas Gleixner > Cc: Will Deacon > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-perf-users@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual Reviewed-by: James Clark > --- > include/uapi/linux/perf_event.h | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h > index 26d8f0b5ac0d..d29280adc3c4 100644 > --- a/include/uapi/linux/perf_event.h > +++ b/include/uapi/linux/perf_event.h > @@ -255,9 +255,22 @@ enum { > PERF_BR_IRQ = 12, /* irq */ > PERF_BR_SERROR = 13, /* system error */ > PERF_BR_NO_TX = 14, /* not in transaction */ > + PERF_BR_EXTEND_ABI = 15, /* extend ABI */ > PERF_BR_MAX, > }; > > +enum { > + PERF_BR_NEW_FAULT_ALGN = 0, /* Alignment fault */ > + PERF_BR_NEW_FAULT_DATA = 1, /* Data fault */ > + PERF_BR_NEW_FAULT_INST = 2, /* Inst fault */ > + PERF_BR_NEW_ARCH_1 = 3, /* Architecture specific */ > + PERF_BR_NEW_ARCH_2 = 4, /* Architecture specific */ > + PERF_BR_NEW_ARCH_3 = 5, /* Architecture specific */ > + PERF_BR_NEW_ARCH_4 = 6, /* Architecture specific */ > + PERF_BR_NEW_ARCH_5 = 7, /* Architecture specific */ > + PERF_BR_NEW_MAX, > +}; > + > #define PERF_SAMPLE_BRANCH_PLM_ALL \ > (PERF_SAMPLE_BRANCH_USER|\ > PERF_SAMPLE_BRANCH_KERNEL|\ > @@ -1372,7 +1385,8 @@ struct perf_branch_entry { > abort:1, /* transaction abort */ > cycles:16, /* cycle count to last branch */ > type:4, /* branch type */ > - reserved:40; > + new_type:4, /* additional branch type */ > + reserved:36; > }; > > union perf_sample_weight {