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=-6.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 A3EA6C433ED for ; Wed, 28 Apr 2021 13:10:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 688CB61419 for ; Wed, 28 Apr 2021 13:10:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239620AbhD1NLj (ORCPT ); Wed, 28 Apr 2021 09:11:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:45480 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239201AbhD1NLj (ORCPT ); Wed, 28 Apr 2021 09:11:39 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id F114D613C2; Wed, 28 Apr 2021 13:10:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1619615454; bh=2Ibkd7Pge7HJjN3dGzr1Td0vru6DS1RxYXZaon8ku3k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QM1wPsmh/cx5qTIq9qICo7EkJtksp+xW0piMTnLgCiK0zXj4mPKWwd6HQsTjVkdrL OEcBHAe+QZ5efxnSBu09tqP952fEEfmNkSs6f6ytlfsnbMPAm14nm/3j8qMmGa+NFn 9xTE6ZFTkMoIfclhut6rFfM0EVxDfol0DzF9iwDVhNWSM1PQdrh6tF9z3NMRNMsjcy RAthyG+J9bIbJS9KJdLOf4B3qTp9fOWZ3YA8hNwVfzFkClCjhfduqSl241/Miu2TnT B3w3POZVW6CezKXqTdGNj26HUyPMohk9qO3uVQsSKqpGH73wgGaPClLlESYNS/fVYa phiU4brxGLkdQ== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 81E2940647; Wed, 28 Apr 2021 10:10:50 -0300 (-03) Date: Wed, 28 Apr 2021 10:10:50 -0300 From: Arnaldo Carvalho de Melo To: Andrii Nakryiko Cc: Jiri Olsa , Martin KaFai Lau , Jiri Olsa , dwarves@vger.kernel.org, bpf , Kernel Team , Andrii Nakryiko Subject: Re: [PATCH dwarves] btf: Generate btf for functions in the .BTF_ids section Message-ID: References: <20210423213728.3538141-1-kafai@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Url: http://acmel.wordpress.com Precedence: bulk List-ID: X-Mailing-List: dwarves@vger.kernel.org Em Tue, Apr 27, 2021 at 01:38:51PM -0700, Andrii Nakryiko escreveu: > On Tue, Apr 27, 2021 at 5:34 AM Arnaldo Carvalho de Melo wrote: > > And tools that expect to trace a function can get that information from > > the BTF info instead of getting some failure when trying to trace those > > functions, right? > I don't think it belongs in BTF, though. My thinking was that since BTF is used when tracing, one would be interested in knowing if some functions can't be used for that. > Plus there are additional limitations enforced by BPF verifier that > will prevent some functions to be attached. So just because the > function is in BTF doesn't mean it's 100% attachable. Well, at least we would avoid some that can't for sure be used for tracing. But, a bit in there is precious, so probably geting a NACK from the kernel should be a good enough capability query. :-) Tools should just silently prune things in wildcards provided by the user that aren't traceable, silently, and provide an error message when the user explicitely asks for tracing a verbotten function. - Arnaldo