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=-3.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,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 A43FCC43143 for ; Wed, 5 Sep 2018 22:05:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A1A920839 for ; Wed, 5 Sep 2018 22:05:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="x2tYt4ka" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5A1A920839 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727840AbeIFChK (ORCPT ); Wed, 5 Sep 2018 22:37:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:51042 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727518AbeIFChK (ORCPT ); Wed, 5 Sep 2018 22:37:10 -0400 Received: from jouet.infradead.org (unknown [179.97.41.186]) (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 721D42077C; Wed, 5 Sep 2018 22:04:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1536185098; bh=3cPm6dPWGsgT4eEKf2tLfrb7CkVC1KEd/Zd9b3zli7Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=x2tYt4kalgSHz7SBytcJCSwGSl+VwvFmtwUTCuPYJJnNouKo9OTFTl9FX8AJf8+8N kl2CLQbiLexEeixjZx2vEXPRUhCzQfi0/OxMFzlmtTenVv4wmhB8McZzRoV3t/jZOK sI8mogrlaVk+Jr+CruUrLZLrzohYZZCk6aWXiuUU= From: Arnaldo Carvalho de Melo To: Ingo Molnar Cc: Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Arnaldo Carvalho de Melo , Adrian Hunter , David Ahern , Jiri Olsa , Namhyung Kim , Wang Nan Subject: [PATCH 02/77] perf trace: Make the augmented_syscalls filter out the tracepoint event Date: Wed, 5 Sep 2018 19:03:25 -0300 Message-Id: <20180905220440.20256-3-acme@kernel.org> X-Mailer: git-send-email 2.14.4 In-Reply-To: <20180905220440.20256-1-acme@kernel.org> References: <20180905220440.20256-1-acme@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnaldo Carvalho de Melo When we attach a eBPF object to a tracepoint, if we return 1, then that tracepoint will be stored in the perf's ring buffer. In the augmented_syscalls.c case we want to just attach and _override_ the tracepoint payload with an augmented, extended one. In this example, tools/perf/examples/bpf/augmented_syscalls.c, we are attaching to the 'openat' syscall, and adding, after the syscalls:sys_enter_openat usual payload as defined by /sys/kernel/debug/tracing/events/syscalls/sys_enter_openat/format, a snapshot of its sole pointer arg: # grep 'field:.*\*' /sys/kernel/debug/tracing/events/syscalls/sys_enter_openat/format field:const char * filename; offset:24; size:8; signed:0; # For now this is not being considered, the next csets will make use of it, but as this is overriding the syscall tracepoint enter, we don't want that event appearing on the ring buffer, just our synthesized one. Before: # perf trace -e ~acme/git/perf/tools/perf/examples/bpf/augmented_syscalls.c,openat cat /etc/passwd > /dev/null 0.000 ( ): __augmented_syscalls__:dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC 0.006 ( ): syscalls:sys_enter_openat:dfd: CWD, filename: , flags: CLOEXEC 0.007 ( 0.004 ms): cat/24044 openat(dfd: CWD, filename: 0x216dda8, flags: CLOEXEC ) = 3 0.028 ( ): __augmented_syscalls__:dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC 0.030 ( ): syscalls:sys_enter_openat:dfd: CWD, filename: , flags: CLOEXEC 0.031 ( 0.006 ms): cat/24044 openat(dfd: CWD, filename: 0x2375ce0, flags: CLOEXEC ) = 3 0.291 ( ): __augmented_syscalls__:dfd: CWD, filename: /etc/passwd 0.293 ( ): syscalls:sys_enter_openat:dfd: CWD, filename: 0.294 ( 0.004 ms): cat/24044 openat(dfd: CWD, filename: 0x637db06b ) = 3 # After: # perf trace -e ~acme/git/perf/tools/perf/examples/bpf/augmented_syscalls.c,openat cat /etc/passwd > /dev/null 0.000 ( ): __augmented_syscalls__:dfd: CWD, filename: 0x9c6a1da8, flags: CLOEXEC 0.005 ( 0.015 ms): cat/27341 openat(dfd: CWD, filename: 0x9c6a1da8, flags: CLOEXEC ) = 3 0.040 ( ): __augmented_syscalls__:dfd: CWD, filename: 0x9c8a9ce0, flags: CLOEXEC 0.041 ( 0.006 ms): cat/27341 openat(dfd: CWD, filename: 0x9c8a9ce0, flags: CLOEXEC ) = 3 0.294 ( ): __augmented_syscalls__:dfd: CWD, filename: 0x482a706b 0.296 ( 0.067 ms): cat/27341 openat(dfd: CWD, filename: 0x482a706b ) = 3 # Now lets replace that __augmented_syscalls__ name with the syscall name, using: # grep 'field:.*syscall_nr' /sys/kernel/debug/tracing/events/syscalls/sys_enter_openat/format field:int __syscall_nr; offset:8; size:4; signed:1; # That the synthesized payload has exactly where the syscall enter tracepoint puts it. Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-og4r9k87mzp9hv7el046idmd@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/examples/bpf/augmented_syscalls.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/perf/examples/bpf/augmented_syscalls.c b/tools/perf/examples/bpf/augmented_syscalls.c index 69a31386d8cd..10e7997ab481 100644 --- a/tools/perf/examples/bpf/augmented_syscalls.c +++ b/tools/perf/examples/bpf/augmented_syscalls.c @@ -49,7 +49,7 @@ int syscall_enter(openat)(struct syscall_enter_openat_args *args) probe_read_str(&augmented_args.filename, sizeof(augmented_args.filename), args->filename_ptr); perf_event_output(args, &__augmented_syscalls__, BPF_F_CURRENT_CPU, &augmented_args, sizeof(augmented_args)); - return 1; + return 0; } license(GPL); -- 2.14.4