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=-5.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 45C16C4743D for ; Tue, 8 Jun 2021 18:17:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 29AF161376 for ; Tue, 8 Jun 2021 18:17:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233934AbhFHSTI (ORCPT ); Tue, 8 Jun 2021 14:19:08 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:48329 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233651AbhFHSTG (ORCPT ); Tue, 8 Jun 2021 14:19:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623176231; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=FgcNrFAjjDfM6kscY0HroHEpq/799D0mYtyjXFcJssg=; b=KLI/LlQfBcxH3f6cTiLoaZ9YqnoS54eKyF0WmMcpUFIR6kgqO7oLTPNmPh9M3erj487lwR stzOgl5mPoI2P5Pr/RJtTfJY2hRgEp4QqToh9gWDnmvbwE5Iwe9LJSxX7mq/hKBD5mAbQ/ xopfDctOOa5lQJQOPZ1DUhEbAQlmtnU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-436-snZbmUCDPcKyjcBflb7kmw-1; Tue, 08 Jun 2021 14:17:08 -0400 X-MC-Unique: snZbmUCDPcKyjcBflb7kmw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 1159D8189C6; Tue, 8 Jun 2021 18:17:05 +0000 (UTC) Received: from krava (unknown [10.40.195.112]) by smtp.corp.redhat.com (Postfix) with SMTP id 2B1D0620DE; Tue, 8 Jun 2021 18:17:01 +0000 (UTC) Date: Tue, 8 Jun 2021 20:17:00 +0200 From: Jiri Olsa To: Alexei Starovoitov Cc: Jiri Olsa , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , "Steven Rostedt (VMware)" , Network Development , bpf , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Daniel Xu , Viktor Malik Subject: Re: [PATCH 13/19] bpf: Add support to link multi func tracing program Message-ID: References: <20210605111034.1810858-1-jolsa@kernel.org> <20210605111034.1810858-14-jolsa@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Jun 08, 2021 at 08:42:32AM -0700, Alexei Starovoitov wrote: > On Sat, Jun 5, 2021 at 4:11 AM Jiri Olsa wrote: > > > > Adding support to attach multiple functions to tracing program > > by using the link_create/link_update interface. > > > > Adding multi_btf_ids/multi_btf_ids_cnt pair to link_create struct > > API, that define array of functions btf ids that will be attached > > to prog_fd. > > > > The prog_fd needs to be multi prog tracing program (BPF_F_MULTI_FUNC). > > > > The new link_create interface creates new BPF_LINK_TYPE_TRACING_MULTI > > link type, which creates separate bpf_trampoline and registers it > > as direct function for all specified btf ids. > > > > The new bpf_trampoline is out of scope (bpf_trampoline_lookup) of > > standard trampolines, so all registered functions need to be free > > of direct functions, otherwise the link fails. > > Overall the api makes sense to me. > The restriction of multi vs non-multi is too severe though. > The multi trampoline can serve normal fentry/fexit too. so multi trampoline gets called from all the registered functions, so there would need to be filter for specific ip before calling the standard program.. single cmp/jnz might not be that bad, I'll check > If ip is moved to the end (instead of start) the trampoline > will be able to call into multi and normal fentry/fexit progs. Right? > we could just skip ip arg when generating entry for normal programs and start from first argument address for %rdi and it'd need to be transparent for current trampolines user API, so I wonder there will be some hiccup ;-) let's see thanks, jirka