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=-16.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 37D68C433E9 for ; Wed, 17 Feb 2021 12:45:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 078CD64D7F for ; Wed, 17 Feb 2021 12:45:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232760AbhBQMpd (ORCPT ); Wed, 17 Feb 2021 07:45:33 -0500 Received: from mail.kernel.org ([198.145.29.99]:54496 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232615AbhBQMpc (ORCPT ); Wed, 17 Feb 2021 07:45:32 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 86CB764E42; Wed, 17 Feb 2021 12:44:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1613565890; bh=WcU8ALpWENrCV4CpD1hmI2qKUhbciDlEwL7Vn5XgLyM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ARFZSczMhlO4QuTznVeDrYe0h8ECYqioqYjw3Wzkxa3hSjrBeTKW+AedAEnVRpXiG 8i7q0Kd2b2DTUSNXKFLHeSzX9fBAm4CfXJGM5hHMiW7D8Q/dFvOHl4I+h2UimjXCA+ CEEyxDfEVTFhfpqGoGe0RrbQA82TjR2D2uGFsejPHFmWtNY+QlnCzMjJ3iLfQXo+bA fSq4IenBru4zfyk4GWSg8jG9eiKSAa/ZIIgmOVB4y1+BYQ7EbVfiLc45sqFWpER/dn gEHUUTGO1V+g7/x6N2FbzYfo/wGEzgbDhVG1LkOnE3ar2rE1R8jmH7ysDdUE+6rNY+ Q3/LDJHCcH/aw== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id 81CDC40CD9; Wed, 17 Feb 2021 09:44:48 -0300 (-03) Date: Wed, 17 Feb 2021 09:44:48 -0300 From: Arnaldo Carvalho de Melo To: Sedat Dilek Cc: Jiri Olsa , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Andrii Nakryiko , dwarves@vger.kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, Yonghong Song , Hao Luo , Martin KaFai Lau , Song Liu , John Fastabend , KP Singh , Nathan Chancellor Subject: Re: [PATCHv2] btf_encoder: Match ftrace addresses within elf functions Message-ID: References: <20210213164648.1322182-1-jolsa@kernel.org> 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: netdev@vger.kernel.org Em Sat, Feb 13, 2021 at 08:11:40PM +0100, Sedat Dilek escreveu: > On Sat, Feb 13, 2021 at 5:46 PM Jiri Olsa wrote: > > > > Currently when processing DWARF function, we check its entrypoint > > against ftrace addresses, assuming that the ftrace address matches > > with function's entrypoint. > > > > This is not the case on some architectures as reported by Nathan > > when building kernel on arm [1]. > > > > Fixing the check to take into account the whole function not > > just the entrypoint. > > > > Most of the is_ftrace_func code was contributed by Andrii. > > > > [1] https://lore.kernel.org/bpf/20210209034416.GA1669105@ubuntu-m3-large-x86/ > > Acked-by: Andrii Nakryiko > > Signed-off-by: Jiri Olsa > > Tested this v2 together with "btf_encoder: sanitize non-regular int > base type" v2 on top of pahole v1.20 > > Tested-by: Sedat Dilek # Linux v5.11-rc7+ and > LLVM/Clang v12.0.0-rc1 on x86 (64bit) Thanks, added to the cset, - Arnaldo > - Sedat - > > > --- > > v2 changes: > > - update functions addr directly [Andrii] > > > > btf_encoder.c | 40 ++++++++++++++++++++++++++++++++++++++-- > > 1 file changed, 38 insertions(+), 2 deletions(-) > > > > diff --git a/btf_encoder.c b/btf_encoder.c > > index b124ec20a689..80e896961d4e 100644 > > --- a/btf_encoder.c > > +++ b/btf_encoder.c > > @@ -36,6 +36,7 @@ struct funcs_layout { > > struct elf_function { > > const char *name; > > unsigned long addr; > > + unsigned long size; > > unsigned long sh_addr; > > bool generated; > > }; > > @@ -98,6 +99,7 @@ static int collect_function(struct btf_elf *btfe, GElf_Sym *sym, > > > > functions[functions_cnt].name = name; > > functions[functions_cnt].addr = elf_sym__value(sym); > > + functions[functions_cnt].size = elf_sym__size(sym); > > functions[functions_cnt].sh_addr = sh.sh_addr; > > functions[functions_cnt].generated = false; > > functions_cnt++; > > @@ -236,6 +238,39 @@ get_kmod_addrs(struct btf_elf *btfe, __u64 **paddrs, __u64 *pcount) > > return 0; > > } > > > > +static int is_ftrace_func(struct elf_function *func, __u64 *addrs, __u64 count) > > +{ > > + __u64 start = func->addr; > > + __u64 addr, end = func->addr + func->size; > > + > > + /* > > + * The invariant here is addr[r] that is the smallest address > > + * that is >= than function start addr. Except the corner case > > + * where there is no such r, but for that we have a final check > > + * in the return. > > + */ > > + size_t l = 0, r = count - 1, m; > > + > > + /* make sure we don't use invalid r */ > > + if (count == 0) > > + return false; > > + > > + while (l < r) { > > + m = l + (r - l) / 2; > > + addr = addrs[m]; > > + > > + if (addr >= start) { > > + /* we satisfy invariant, so tighten r */ > > + r = m; > > + } else { > > + /* m is not good enough as l, maybe m + 1 will be */ > > + l = m + 1; > > + } > > + } > > + > > + return start <= addrs[r] && addrs[r] < end; > > +} > > + > > static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) > > { > > __u64 *addrs, count, i; > > @@ -283,10 +318,11 @@ static int setup_functions(struct btf_elf *btfe, struct funcs_layout *fl) > > * functions[x]::addr is relative address within section > > * and needs to be relocated by adding sh_addr. > > */ > > - __u64 addr = kmod ? func->addr + func->sh_addr : func->addr; > > + if (kmod) > > + func->addr += func->sh_addr; > > > > /* Make sure function is within ftrace addresses. */ > > - if (bsearch(&addr, addrs, count, sizeof(addrs[0]), addrs_cmp)) { > > + if (is_ftrace_func(func, addrs, count)) { > > /* > > * We iterate over sorted array, so we can easily skip > > * not valid item and move following valid field into > > -- > > 2.29.2 > > -- - Arnaldo