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 21D55C77B7C for ; Fri, 5 May 2023 13:18:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232058AbjEENSM (ORCPT ); Fri, 5 May 2023 09:18:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232370AbjEENSL (ORCPT ); Fri, 5 May 2023 09:18:11 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9CB82699; Fri, 5 May 2023 06:18:09 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 0182860A71; Fri, 5 May 2023 13:18:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E735C433EF; Fri, 5 May 2023 13:18:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1683292688; bh=iWuVMtbZc8fX58fKAMNGGbRV6grNa+1PwhlQF6nB89w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=S35fn3fxmBi+6jrRNiFXaSAC30eGZPm5Rkh1QJQgPtnF7tFmgi7tb6ddOydiLE6om 7Gjv4ZuG4WmfLsZ0dSiVV8a7v0Zp2DcKKYCBtGTsWyrgsFeaSk0f8CYsO+0iewbAMM Ahb6wb5/sTjdVBBzRJ0NJSfJu8TIqhiVuv7Lrm6oketO3vo+F5bEP6dwpZS5E4Zzfe ZaXHWQwCesJhtU23Y1DWwYZWwfPmyobsrXya4D5V5eZLZO1N3CUObCjj8oclaO46VB A7mcIl9HDHQydU25b2IdCirzsW4I79Klrut2T+5xqyTFsVWbwTDH4fFupjaIhnuic4 5GR2x18K4OHlQ== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 4BA9E403B5; Fri, 5 May 2023 10:18:05 -0300 (-03) Date: Fri, 5 May 2023 10:18:05 -0300 From: Arnaldo Carvalho de Melo To: Yang Jihong , Andrii Nakryiko Cc: Linus Torvalds , Song Liu , Andrii Nakryiko , Ingo Molnar , Thomas Gleixner , Jiri Olsa , Clark Williams , Kate Carcia , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Adrian Hunter , Changbin Du , Hao Luo , Ian Rogers , James Clark , Kan Liang , Roman Lozko , Stephane Eranian , Thomas Richter , Arnaldo Carvalho de Melo , bpf Subject: Re: BPF skels in perf .Re: [GIT PULL] perf tools changes for v6.4 Message-ID: References: <20230503211801.897735-1-acme@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Url: http://acmel.wordpress.com Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org Em Thu, May 04, 2023 at 07:01:51PM -0300, Arnaldo Carvalho de Melo escreveu: > Em Thu, May 04, 2023 at 06:48:50PM -0300, Arnaldo Carvalho de Melo escreveu: > > Em Thu, May 04, 2023 at 04:07:29PM -0300, Arnaldo Carvalho de Melo escreveu: > > > Em Thu, May 04, 2023 at 11:50:07AM -0700, Andrii Nakryiko escreveu: > > > > On Thu, May 4, 2023 at 10:52 AM Arnaldo Carvalho de Melo wrote: > > > > > Andrii, can you add some more information about the usage of vmlinux.h > > > > > instead of using kernel headers? > > > > > > > I'll just say that vmlinux.h is not a hard requirement to build BPF > > > > programs, it's more a convenience allowing easy access to definitions > > > > of both UAPI and kernel-internal structures for tracing needs and > > > > marking them relocatable using BPF CO-RE machinery. Lots of real-world > > > > applications just check-in pregenerated vmlinux.h to avoid build-time > > > > dependency on up-to-date host kernel and such. > > > > > > > If vmlinux.h generation and usage is causing issues, though, given > > > > that perf's BPF programs don't seem to be using many different kernel > > > > types, it might be a better option to just use UAPI headers for public > > > > kernel type definitions, and just define CO-RE-relocatable minimal > > > > definitions locally in perf's BPF code for the other types necessary. > > > > E.g., if perf needs only pid and tgid from task_struct, this would > > > > suffice: > > > > > > > struct task_struct { > > > > int pid; > > > > int tgid; > > > > } __attribute__((preserve_access_index)); > > > > > > Yeah, that seems like a way better approach, no vmlinux involved, libbpf > > > CO-RE notices that task_struct changed from this two integers version > > > (of course) and does the relocation to where it is in the running kernel > > > by using /sys/kernel/btf/vmlinux. > > > > Doing it for one of the skels, build tested, runtime untested, but not > > using any vmlinux, BTF to help, not that bad, more verbose, but at least > > we state what are the fields we actually use, have those attribute > > documenting that those offsets will be recorded for future use, etc. Yang, can you please check that this works? >From bd6289bc3ffc89aecad3bd8798d76626c8c16d39 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Fri, 5 May 2023 10:13:09 -0300 Subject: [PATCH 1/1] perf kwork_trace.bpf: Stop using vmlinux.h, grab copies of used structs And mark them with __attribute__((preserve_access_index)) so that libbpf's CO-RE code can fixup offsets if they differ with the kernel data structure. Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/bpf_skel/kwork_trace.bpf.c | 70 +++++++++++++++++++++- 1 file changed, 69 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/bpf_skel/kwork_trace.bpf.c b/tools/perf/util/bpf_skel/kwork_trace.bpf.c index 063c124e099938ed..e38fe54c7667fa74 100644 --- a/tools/perf/util/bpf_skel/kwork_trace.bpf.c +++ b/tools/perf/util/bpf_skel/kwork_trace.bpf.c @@ -1,13 +1,81 @@ // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) // Copyright (c) 2022, Huawei -#include "vmlinux.h" +#include #include #include #define KWORK_COUNT 100 #define MAX_KWORKNAME 128 + +// non-UAPI kernel data structures, just the fields used in this tool, +// preserving the access index so that libbpf can fixup offsets with the ones +// used in the kernel when loading the BPF bytecode, if they differ from what +// is used here. + +enum { + HI_SOFTIRQ = 0, + TIMER_SOFTIRQ, + NET_TX_SOFTIRQ, + NET_RX_SOFTIRQ, + BLOCK_SOFTIRQ, + IRQ_POLL_SOFTIRQ, + TASKLET_SOFTIRQ, + SCHED_SOFTIRQ, + HRTIMER_SOFTIRQ, + RCU_SOFTIRQ, /* Preferable RCU should always be the last softirq */ + + NR_SOFTIRQS +}; + +struct trace_entry { + short unsigned int type; + unsigned char flags; + unsigned char preempt_count; + int pid; +} __attribute__((preserve_access_index)); + +struct trace_event_raw_irq_handler_entry { + struct trace_entry ent; + int irq; + __u32 __data_loc_name; + char __data[]; +} __attribute__((preserve_access_index)); + +struct trace_event_raw_irq_handler_exit { + struct trace_entry ent; + int irq; + int ret; + char __data[]; +} __attribute__((preserve_access_index)); + +struct trace_event_raw_softirq { + struct trace_entry ent; + unsigned int vec; + char __data[]; +} __attribute__((preserve_access_index)); + +struct trace_event_raw_workqueue_execute_start { + struct trace_entry ent; + void *work; + void *function; + char __data[]; +} __attribute__((preserve_access_index)); + +struct trace_event_raw_workqueue_execute_end { + struct trace_entry ent; + void *work; + void *function; + char __data[]; +} __attribute__((preserve_access_index)); + +struct trace_event_raw_workqueue_activate_work { + struct trace_entry ent; + void *work; + char __data[]; +} __attribute__((preserve_access_index)); + /* * This should be in sync with "util/kwork.h" */ -- 2.39.2