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=-0.8 required=3.0 tests=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 20C86C433E1 for ; Wed, 13 May 2020 22:48:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E1CF2065C for ; Wed, 13 May 2020 22:48:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731839AbgEMWsf (ORCPT ); Wed, 13 May 2020 18:48:35 -0400 Received: from smtprelay0137.hostedemail.com ([216.40.44.137]:53570 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731649AbgEMWsd (ORCPT ); Wed, 13 May 2020 18:48:33 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay02.hostedemail.com (Postfix) with ESMTP id C68353AA1; Wed, 13 May 2020 22:48:31 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: jail30_fefc17eb803f X-Filterd-Recvd-Size: 2415 Received: from XPS-9350.home (unknown [47.151.136.130]) (Authenticated sender: joe@perches.com) by omf08.hostedemail.com (Postfix) with ESMTPA; Wed, 13 May 2020 22:48:29 +0000 (UTC) Message-ID: Subject: Re: [PATCH v2 bpf-next 0/7] bpf, printk: add BTF-based type printing From: Joe Perches To: Alexei Starovoitov , Alan Maguire Cc: ast@kernel.org, daniel@iogearbox.net, bpf@vger.kernel.org, linux@rasmusvillemoes.dk, arnaldo.melo@gmail.com, yhs@fb.com, kafai@fb.com, songliubraving@fb.com, andriin@fb.com, john.fastabend@gmail.com, kpsingh@chromium.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Date: Wed, 13 May 2020 15:48:17 -0700 In-Reply-To: <20200513222424.4nfxgkequhdzn3u3@ast-mbp.dhcp.thefacebook.com> References: <1589263005-7887-1-git-send-email-alan.maguire@oracle.com> <20200513222424.4nfxgkequhdzn3u3@ast-mbp.dhcp.thefacebook.com> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.36.1-2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2020-05-13 at 15:24 -0700, Alexei Starovoitov wrote: > On Tue, May 12, 2020 at 06:56:38AM +0100, Alan Maguire wrote: > > The printk family of functions support printing specific pointer types > > using %p format specifiers (MAC addresses, IP addresses, etc). For > > full details see Documentation/core-api/printk-formats.rst. > > > > This patchset proposes introducing a "print typed pointer" format > > specifier "%pT"; the argument associated with the specifier is of > > form "struct btf_ptr *" which consists of a .ptr value and a .type > > value specifying a stringified type (e.g. "struct sk_buff") or > > an .id value specifying a BPF Type Format (BTF) id identifying > > the appropriate type it points to. > > > > pr_info("%pT", BTF_PTR_TYPE(skb, "struct sk_buff")); > > > > ...gives us: > > > > (struct sk_buff){ > > .transport_header = (__u16)65535, > > .mac_header = (__u16)65535, > > .end = (sk_buff_data_t)192, > > .head = (unsigned char *)000000007524fd8b, > > .data = (unsigned char *)000000007524fd8b, > > could you add "0x" prefix here to make it even more C like > and unambiguous ? linux pointers are not emitted with an 0x prefix (ie: pointers do not use SPECIAL in lib/vsprintf.c)