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=-5.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 05730C3A5A5 for ; Mon, 2 Sep 2019 14:15:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA25D2173E for ; Mon, 2 Sep 2019 14:15:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="mj/Q0Kso" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730872AbfIBOPb (ORCPT ); Mon, 2 Sep 2019 10:15:31 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:37973 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726824AbfIBOPa (ORCPT ); Mon, 2 Sep 2019 10:15:30 -0400 Received: by mail-qk1-f194.google.com with SMTP id u190so12640405qkh.5 for ; Mon, 02 Sep 2019 07:15:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=vg5cV8RgYZAUwO4BlUHQDzrdFcjapkG4a4PKGmuKmDk=; b=mj/Q0KsoKkL2aU8JZYYOHHonFGHI32S47bwd5c/tBzZWVQqk20Z5lLx+BxwVj/27qU CVKjoFn4KS2uLQ/mVkJkNF2mAgDtmCdpBVGUKns+p5oTekFtv67IL8RRWmpZqFtxaZ3U v2gxg4Ku+yL/kAxYWoaL9NFMXqoa40a0L1BCLjo/4mrl/lj0XaHeavdXQVStmMlhMohI GtAbBq5vOdH/MuvS6pe6D9Sdce9cGAjxA0OGr3pmJ+a3bnABM0SX6/QPtxwY8LhWztnJ GuG0qHfkIj9uf2P8ls1l987c+SgQm0iqRt/CuNzTsAGgvJIL4p+Kb21tQgfa6Cxq6myZ wTUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=vg5cV8RgYZAUwO4BlUHQDzrdFcjapkG4a4PKGmuKmDk=; b=uW0JawJbXKNnnnz4BqPf8qMlCKPu4XrHI33zXnJcC11O82fB457iVtSD8V3C9xc0f5 w3vTAkQ6R9NevQrxgoTc8JezVA5ussPSsgye/Z9JBseKFMEs89Sm3paost/oM4YKMh6S Mcoe/Mdf8XWpkIgZ469aTMWCrbMsonMyGLzUAV6STvS1CGNcYDC4gJeoz/DQMBR02whm qnkbUo5+iDjr36/CQ7DvtiBIQrgVsdJNYIEpbriJvNCjTdYXvHj5yRzDlW9pKMKA68Dn FlexSwoJcVwlUdR7wM8KR+05kkcsBlq/iAb87kW6bBhP8oKsvTly9Sz9OCk/f6xrEaDN WS4w== X-Gm-Message-State: APjAAAWvLPflELpBa8w88Y74v6hPNSFKNvhK59YXX4Im6yoWpBRxfT2S ibcip2ncGJwCS3TQ/a+iN5IIYg== X-Google-Smtp-Source: APXvYqwh5YLrf3v8H14X6qT6Rudakihge2BEBvIqE2ipHpxFGIlfyf61HS+kjaheOm4zXVDWDgA7sA== X-Received: by 2002:a37:de14:: with SMTP id h20mr26496247qkj.260.1567433729523; Mon, 02 Sep 2019 07:15:29 -0700 (PDT) Received: from leoy-ThinkPad-X240s (li1320-244.members.linode.com. [45.79.221.244]) by smtp.gmail.com with ESMTPSA id d45sm3752547qtc.70.2019.09.02.07.15.17 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 02 Sep 2019 07:15:28 -0700 (PDT) Date: Mon, 2 Sep 2019 22:15:11 +0800 From: Leo Yan To: Adrian Hunter Cc: Arnaldo Carvalho de Melo , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, clang-built-linux@googlegroups.com, Mathieu Poirier , Peter Zijlstra , Suzuki Poulouse , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v5] perf machine: arm/arm64: Improve completeness for kernel address space Message-ID: <20190902141511.GF4931@leoy-ThinkPad-X240s> References: <20190815082521.16885-1-leo.yan@linaro.org> <20190815113242.GA28881@leoy-ThinkPad-X240s> <20190816014541.GA17960@leoy-ThinkPad-X240s> <363577f1-097e-eddd-a6ca-b23f644dd8ce@intel.com> <20190826125105.GA3288@leoy-ThinkPad-X240s> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190826125105.GA3288@leoy-ThinkPad-X240s> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi Adrian, On Mon, Aug 26, 2019 at 08:51:05PM +0800, Leo Yan wrote: > Hi Adrian, > > On Fri, Aug 16, 2019 at 04:00:02PM +0300, Adrian Hunter wrote: > > On 16/08/19 4:45 AM, Leo Yan wrote: > > > Hi Adrian, > > > > > > On Thu, Aug 15, 2019 at 02:45:57PM +0300, Adrian Hunter wrote: > > > > > > [...] > > > > > >>>> How come you cannot use kallsyms to get the information? > > >>> > > >>> Thanks for pointing out this. Sorry I skipped your comment "I don't > > >>> know how you intend to calculate ARM_PRE_START_SIZE" when you reviewed > > >>> the patch v3, I should use that chance to elaborate the detailed idea > > >>> and so can get more feedback/guidance before procceed. > > >>> > > >>> Actually, I have considered to use kallsyms when worked on the previous > > >>> patch set. > > >>> > > >>> As mentioned in patch set v4's cover letter, I tried to implement > > >>> machine__create_extra_kernel_maps() for arm/arm64, the purpose is to > > >>> parse kallsyms so can find more kernel maps and thus also can fixup > > >>> the kernel start address. But I found the 'perf script' tool directly > > >>> calls machine__get_kernel_start() instead of running into the flow for > > >>> machine__create_extra_kernel_maps(); > > >> > > >> Doesn't it just need to loop through each kernel map to find the lowest > > >> start address? > > > > > > Based on your suggestion, I worked out below change and verified it > > > can work well on arm64 for fixing up start address; please let me know > > > if the change works for you? > > > > How does that work if take a perf.data file to a machine with a different > > architecture? > > Sorry I delayed so long to respond to your question; I didn't have > confidence to give out very reasonale answer and this is the main reason > for delaying. Could you take chance to review my below replying? I'd like to get your confirmation before I send out offical patch. Thanks, Leo Yan > > For your question for taking a perf.data file to a machine with a > different architecture, we can firstly use command 'perf buildid-list' > to print out the buildid for kallsyms, based on the dumped buildid we > can find out the location for the saved kallsyms file; then we can use > option '--kallsyms' to specify the offline kallsyms file and use the > offline kallsyms to fixup kernel start address. The detailed commands > are listed as below: > > root@debian:~# perf buildid-list > 7b36dfca8317ef74974ebd7ee5ec0a8b35c97640 [kernel.kallsyms] > 56b84aa88a1bcfe222a97a53698b92723a3977ca /usr/lib/systemd/systemd > 0956b952e9cd673d48ff2cfeb1a9dbd0c853e686 /usr/lib/aarch64-linux-gnu/libm-2.28.so > [...] > > root@debian:~# perf script --kallsyms ~/.debug/\[kernel.kallsyms\]/7b36dfca8317ef74974ebd7ee5ec0a8b35c97640/kallsyms > > The amended patch is as below, please review and always welcome > any suggestions or comments! > > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c > index 5734460fc89e..593f05cc453f 100644 > --- a/tools/perf/util/machine.c > +++ b/tools/perf/util/machine.c > @@ -2672,9 +2672,26 @@ int machine__nr_cpus_avail(struct machine *machine) > return machine ? perf_env__nr_cpus_avail(machine->env) : 0; > } > > +static int machine__fixup_kernel_start(void *arg, > + const char *name __maybe_unused, > + char type, > + u64 start) > +{ > + struct machine *machine = arg; > + > + type = toupper(type); > + > + /* Fixup for text, weak, data and bss sections. */ > + if (type == 'T' || type == 'W' || type == 'D' || type == 'B') > + machine->kernel_start = min(machine->kernel_start, start); > + > + return 0; > +} > + > int machine__get_kernel_start(struct machine *machine) > { > struct map *map = machine__kernel_map(machine); > + char filename[PATH_MAX]; > int err = 0; > > /* > @@ -2696,6 +2713,22 @@ int machine__get_kernel_start(struct machine *machine) > if (!err && !machine__is(machine, "x86_64")) > machine->kernel_start = map->start; > } > + > + if (symbol_conf.kallsyms_name != NULL) { > + strncpy(filename, symbol_conf.kallsyms_name, PATH_MAX); > + } else { > + machine__get_kallsyms_filename(machine, filename, PATH_MAX); > + > + if (symbol__restricted_filename(filename, "/proc/kallsyms")) > + goto out; > + } > + > + if (kallsyms__parse(filename, machine, machine__fixup_kernel_start)) > + pr_warning("Fail to fixup kernel start address. skipping...\n"); > + > +out: > return err; > } > > > Thanks, > Leo Yan