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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 929E4C43461 for ; Wed, 16 Sep 2020 20:08:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4701E21655 for ; Wed, 16 Sep 2020 20:08:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Tsxpr+qE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728251AbgIPUI2 (ORCPT ); Wed, 16 Sep 2020 16:08:28 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:32598 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727156AbgIPReO (ORCPT ); Wed, 16 Sep 2020 13:34:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600277650; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=oe2E/0j87SbF8+LWDnatG5uzDl9gHzTaZ0sjQBiPp+U=; b=Tsxpr+qEs0KxYcfGUGAsKW6xjJk2NgxziJ6WqrKCD55+QANKpzfHv25FCaAb6HLsqaql1+ hretkZyx7BGb2UfXpS/09ZHzzVZIRU7CL0UsrE2ZWMAEfdFBCT7usbVDoeAPVy/v54+ZNz WSqFdrHFVGtaOFQgjh6lSd581Rce/vA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-130-8cfANCu1PuamMpyzCO-72g-1; Wed, 16 Sep 2020 11:21:29 -0400 X-MC-Unique: 8cfANCu1PuamMpyzCO-72g-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 9E42C1891E80; Wed, 16 Sep 2020 15:21:27 +0000 (UTC) Received: from krava (ovpn-114-172.ams2.redhat.com [10.36.114.172]) by smtp.corp.redhat.com (Postfix) with SMTP id 8421275261; Wed, 16 Sep 2020 15:21:24 +0000 (UTC) Date: Wed, 16 Sep 2020 17:21:23 +0200 From: Jiri Olsa To: Arnaldo Carvalho de Melo Cc: peterz@infradead.org, Ian Rogers , Jiri Olsa , lkml , Ingo Molnar , Mark Rutland , Namhyung Kim , Alexander Shishkin , Michael Petlan , Song Liu , "Frank Ch. Eigler" , Stephane Eranian , Alexey Budankov , Andi Kleen , Adrian Hunter Subject: Re: [PATCH 16/26] perf tools: Synthesize modules with mmap3 Message-ID: <20200916152123.GH2301783@krava> References: <20200913210313.1985612-1-jolsa@kernel.org> <20200913210313.1985612-17-jolsa@kernel.org> <20200914160758.GK160517@kernel.org> <20200916082018.GA2301783@krava> <20200916140744.GR720847@kernel.org> <20200916141700.GC1362448@hirez.programming.kicks-ass.net> <20200916151021.GS720847@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200916151021.GS720847@kernel.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 16, 2020 at 12:10:21PM -0300, Arnaldo Carvalho de Melo wrote: > Em Wed, Sep 16, 2020 at 04:17:00PM +0200, peterz@infradead.org escreveu: > > On Wed, Sep 16, 2020 at 11:07:44AM -0300, Arnaldo Carvalho de Melo wrote: > > > Em Wed, Sep 16, 2020 at 10:20:18AM +0200, Jiri Olsa escreveu: > > > > > > > IIRC BUILD_ID_SIZE is 20 bytes which is the correct size for SHA-1. A > > > > > build ID may be 128-bits (16 bytes) if md5 or uuid hashes are used. > > > > > Should this test just be "> 0" ? > > > > > > > > ah right, will check on that > > > > > > And how do you deal with this in the kernel? I.e. to inform userspace, > > > via the PERF_RECORD_MMAP3 (or MMAP2 with that misc bit trick) the size > > > of the build-id? > > > > The union size is 24 bytes, so there's plenty space to store a length > > field with the buildid. > > So, I think we should instead use a bit in the misc field, stating the > kind of build-id, so that we don't waste a byte for that, I think. not sure there's too many misc bits left if there would be more build id kinds jirka