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=-8.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_AGENT_NEOMUTT autolearn=unavailable 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 D02EAC282E3 for ; Fri, 24 May 2019 13:06:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9FAB2168B for ; Fri, 24 May 2019 13:06:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391577AbfEXNGC (ORCPT ); Fri, 24 May 2019 09:06:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:29648 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391193AbfEXNGB (ORCPT ); Fri, 24 May 2019 09:06:01 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0561E308338F; Fri, 24 May 2019 13:06:01 +0000 (UTC) Received: from treble (ovpn-121-106.rdu2.redhat.com [10.10.121.106]) by smtp.corp.redhat.com (Postfix) with ESMTPS id EEC6F68706; Fri, 24 May 2019 13:05:59 +0000 (UTC) Date: Fri, 24 May 2019 08:05:57 -0500 From: Josh Poimboeuf To: Peter Zijlstra Cc: Kairui Song , Alexei Starovoitov , Song Liu , lkml , Kernel Team , Alexei Starovoitov , Daniel Borkmann , "bpf@vger.kernel.org" Subject: Re: Getting empty callchain from perf_callchain_kernel() Message-ID: <20190524130557.icmofltzzotqvurg@treble> References: <20190522140233.GC16275@worktop.programming.kicks-ass.net> <20190522174517.pbdopvookggen3d7@treble> <20190522234635.a47bettklcf5gt7c@treble> <20190523133253.tad6ywzzexks6hrp@treble> <20190523152413.m2pbnamihu3s2c5s@treble> <20190524085319.GE2589@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190524085319.GE2589@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Fri, 24 May 2019 13:06:01 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 24, 2019 at 10:53:19AM +0200, Peter Zijlstra wrote: > On Thu, May 23, 2019 at 10:24:13AM -0500, Josh Poimboeuf wrote: > > > Here's the latest version which should fix it in all cases (based on > > tip/master): > > > > https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux.git/commit/?h=bpf-orc-fix > > That patch suffers an inconsitency, the comment states: > > 'if they have "jump_table" in the name' > > while the actual code implements: > > 'if the name starts with "jump_table"' > > Other than that, I suppose that works just fine ;-) The thing is, gcc converts a static local variable named "jump_table" to an ELF symbol with a numbered suffix, something like "jump_table.12345". But yeah I should at least clarify that in the comment. -- Josh