From patchwork Mon Feb 8 15:00:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 379228 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=-24.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,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 E0C57C433E6 for ; Mon, 8 Feb 2021 15:13:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A6C4564EF6 for ; Mon, 8 Feb 2021 15:13:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233431AbhBHPNN (ORCPT ); Mon, 8 Feb 2021 10:13:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:56628 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230384AbhBHPKS (ORCPT ); Mon, 8 Feb 2021 10:10:18 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id BF47F64ECC; Mon, 8 Feb 2021 15:07:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612796832; bh=3rCQ7I9TwgVwgGUKfP/9UDumJyWLE6qOc5ewW1LSgEE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V4enW3kb0R7rAzSpsl6j8bqHNemFV0w/50vMtnlMTeVzvSQFGIiioJ7wBJZxcQaqD iVA/fdVYpQWLSpm0ef4Dr6QbJXDQBn5CCm/sjMZBBSixN3V3Qe33hXLWs7IbUfLB8H 7a2SCWvu/MqtwFvm1sUBlqCt5I0kHeXbL4YLlJXw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dmitry Golovin , Josh Poimboeuf , Borislav Petkov , Nathan Chancellor , Miroslav Benes , "Peter Zijlstra (Intel)" Subject: [PATCH 4.14 07/30] objtool: Support Clang non-section symbols in ORC generation Date: Mon, 8 Feb 2021 16:00:53 +0100 Message-Id: <20210208145805.550306003@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210208145805.239714726@linuxfoundation.org> References: <20210208145805.239714726@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Josh Poimboeuf commit e81e0724432542af8d8c702c31e9d82f57b1ff31 upstream. When compiling the kernel with AS=clang, objtool produces a lot of warnings: warning: objtool: missing symbol for section .text warning: objtool: missing symbol for section .init.text warning: objtool: missing symbol for section .ref.text It then fails to generate the ORC table. The problem is that objtool assumes text section symbols always exist. But the Clang assembler is aggressive about removing them. When generating relocations for the ORC table, objtool always tries to reference instructions by their section symbol offset. If the section symbol doesn't exist, it bails. Do a fallback: when a section symbol isn't available, reference a function symbol instead. Reported-by: Dmitry Golovin Signed-off-by: Josh Poimboeuf Signed-off-by: Borislav Petkov Tested-by: Nathan Chancellor Reviewed-by: Miroslav Benes Acked-by: Peter Zijlstra (Intel) Link: https://github.com/ClangBuiltLinux/linux/issues/669 Link: https://lkml.kernel.org/r/9a9cae7fcf628843aabe5a086b1a3c5bf50f42e8.1585761021.git.jpoimboe@redhat.com Signed-off-by: Greg Kroah-Hartman --- tools/objtool/orc_gen.c | 33 ++++++++++++++++++++++++++------- 1 file changed, 26 insertions(+), 7 deletions(-) --- a/tools/objtool/orc_gen.c +++ b/tools/objtool/orc_gen.c @@ -98,11 +98,6 @@ static int create_orc_entry(struct secti struct orc_entry *orc; struct rela *rela; - if (!insn_sec->sym) { - WARN("missing symbol for section %s", insn_sec->name); - return -1; - } - /* populate ORC data */ orc = (struct orc_entry *)u_sec->data->d_buf + idx; memcpy(orc, o, sizeof(*orc)); @@ -115,8 +110,32 @@ static int create_orc_entry(struct secti } memset(rela, 0, sizeof(*rela)); - rela->sym = insn_sec->sym; - rela->addend = insn_off; + if (insn_sec->sym) { + rela->sym = insn_sec->sym; + rela->addend = insn_off; + } else { + /* + * The Clang assembler doesn't produce section symbols, so we + * have to reference the function symbol instead: + */ + rela->sym = find_symbol_containing(insn_sec, insn_off); + if (!rela->sym) { + /* + * Hack alert. This happens when we need to reference + * the NOP pad insn immediately after the function. + */ + rela->sym = find_symbol_containing(insn_sec, + insn_off - 1); + } + if (!rela->sym) { + WARN("missing symbol for insn at offset 0x%lx\n", + insn_off); + return -1; + } + + rela->addend = insn_off - rela->sym->offset; + } + rela->type = R_X86_64_PC32; rela->offset = idx * sizeof(int);