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=-15.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 D287EC76186 for ; Tue, 30 Jul 2019 03:04:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A55FC20578 for ; Tue, 30 Jul 2019 03:04:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564455859; bh=akX8pTRSgtWmvSY+wS4yy14rnr2wZfN2n3Sc5ej76tw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=PTDB6uYnZsBQSLVfFQ9P7QraHYzoXuQF1G6nZvTlD+gQtRJE67j0FPmK1yKs251ML zx60EQcQxUZ9cp2q9IYxazuM2+SN/REWXjpcsg5f7pdPGw8iwhwETAyeADd0C9Pazy pkNHhb0lNcLZTPdJe8vrI/IPg4/a6nRjFz+AQA/8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731644AbfG3C4y (ORCPT ); Mon, 29 Jul 2019 22:56:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:46434 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731618AbfG3C4u (ORCPT ); Mon, 29 Jul 2019 22:56:50 -0400 Received: from quaco.ghostprotocols.net (unknown [179.97.35.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9F335206DD; Tue, 30 Jul 2019 02:56:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564455410; bh=akX8pTRSgtWmvSY+wS4yy14rnr2wZfN2n3Sc5ej76tw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YoZe4XaA+nDT0Lmgk66TJ+/JXsKlT62O6q11BxuVuSg/BVqIqEPW8Vo0rwBTW3QmR phIOzJnWrsH2m7AZBKmVsymbjlE+4iwzrTuQRypgemO5Upxzk4oIFfTBtyXzYWeoOA z58wPlGMCxwhpEVSXinIMe6HdBE4vtC1EYVR6HfY= From: Arnaldo Carvalho de Melo To: Ingo Molnar , Thomas Gleixner Cc: Jiri Olsa , Namhyung Kim , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Arnaldo Carvalho de Melo , Adrian Hunter , =?UTF-8?q?Luis=20Cl=C3=A1udio=20Gon=C3=A7alves?= Subject: [PATCH 010/107] perf trace: Handle raw_syscalls:sys_enter just like the BPF_OUTPUT augmented event Date: Mon, 29 Jul 2019 23:54:33 -0300 Message-Id: <20190730025610.22603-11-acme@kernel.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190730025610.22603-1-acme@kernel.org> References: <20190730025610.22603-1-acme@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnaldo Carvalho de Melo So, we use a PERF_COUNT_SW_BPF_OUTPUT to output the augmented sys_enter payload, i.e. to output more than just the raw syscall args, and if something goes wrong when handling an unfiltered syscall, we bail out and just return 1 in the bpf program associated with raw_syscalls:sys_enter, meaning, don't filter that tracepoint, in which case what will appear in the perf ring buffer isn't the BPF_OUTPUT event, but the original raw_syscalls:sys_enter event with its normal payload. Now that we're switching to using a bpf_tail_call + BPF_MAP_TYPE_PROG_ARRAY we're going to use this in the common case, so a bug where raw_syscalls:sys_enter wasn't being handled by trace__sys_enter() surfaced and for that case, instead of using the strace-like augmenter (trace__sys_enter()), we continued to use the normal generic tracepoint handler: (gdb) p evsel $2 = (struct perf_evsel *) 0xc03e40 (gdb) p evsel->name $3 = 0xbc56c0 "raw_syscalls:sys_enter" (gdb) p ((struct perf_evsel *) 0xc03e40)->name $4 = 0xbc56c0 "raw_syscalls:sys_enter" (gdb) p ((struct perf_evsel *) 0xc03e40)->handler $5 = (void *) 0x495eb3 This resulted in this: 0.027 raw_syscalls:sys_enter:NR 12 (0, 7fcfcac64c9b, 4d, 7fcfcac64c9b, 7fcfcac6ce00, 19) ... [continued]: brk()) = 0x563b88677000 I.e. only the sys_exit tracepoint was being properly handled, but since the sys_enter went to the generic trace__event_handler() we printed it using libtraceevent's formatter instead of 'perf trace's strace-like one. Fix it by setting trace__sys_enter() as the handler for raw_syscalls:sys_enter and setup the tp_field tracepoint field accessors. Now, to test it we just make raw_syscalls:sys_enter return 1 right after checking if the pid is filtered, making it not use bpf_perf_output_event() but rather ask for the tracepoint not to be filtered and the result is the expected one: brk(NULL) = 0x556f42d6e000 I.e. raw_syscalls:sys_enter returns 1, gets handled by trace__sys_enter() and gets it combined with the raw_syscalls:sys_exit in a strace-like way. Cc: Adrian Hunter Cc: Jiri Olsa Cc: Luis Cláudio Gonçalves Cc: Namhyung Kim Link: https://lkml.kernel.org/n/tip-0mkocgk31nmy0odknegcby4z@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/builtin-trace.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c index fb8b8e78d7b5..872c9cc982a5 100644 --- a/tools/perf/builtin-trace.c +++ b/tools/perf/builtin-trace.c @@ -4128,7 +4128,22 @@ int cmd_trace(int argc, const char **argv) if (perf_evsel__init_augmented_syscall_tp(augmented, evsel) || perf_evsel__init_augmented_syscall_tp_args(augmented)) goto out; + /* + * Augmented is __augmented_syscalls__ BPF_OUTPUT event + * Above we made sure we can get from the payload the tp fields + * that we get from syscalls:sys_enter tracefs format file. + */ augmented->handler = trace__sys_enter; + /* + * Now we do the same for the *syscalls:sys_enter event so that + * if we handle it directly, i.e. if the BPF prog returns 0 so + * as not to filter it, then we'll handle it just like we would + * for the BPF_OUTPUT one: + */ + if (perf_evsel__init_augmented_syscall_tp(evsel, evsel) || + perf_evsel__init_augmented_syscall_tp_args(evsel)) + goto out; + evsel->handler = trace__sys_enter; } if (strstarts(perf_evsel__name(evsel), "syscalls:sys_exit_")) { -- 2.21.0