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[2620:137:e000::1:20]) by mx.google.com with ESMTP id n11-20020a1709065e0b00b0098d0a88d4fasi3370125eju.808.2023.09.09.09.25.30; Sat, 09 Sep 2023 09:25:39 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344791AbjIHXNL convert rfc822-to-8bit (ORCPT + 36 others); Fri, 8 Sep 2023 19:13:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55588 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344784AbjIHXNJ (ORCPT ); Fri, 8 Sep 2023 19:13:09 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BDC0118E for ; Fri, 8 Sep 2023 16:13:05 -0700 (PDT) Received: from pps.filterd (m0109331.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 388HqD5G030687 for ; Fri, 8 Sep 2023 16:13:05 -0700 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3t06jvvkdt-5 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 08 Sep 2023 16:13:04 -0700 Received: from twshared52565.14.frc2.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:21d::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Fri, 8 Sep 2023 16:13:01 -0700 Received: by devbig932.frc1.facebook.com (Postfix, from userid 4523) id 01CBF24087ED5; Fri, 8 Sep 2023 16:12:48 -0700 (PDT) From: Song Liu To: CC: , Song Liu , Ricardo Ribalda , Sami Tolvanen , , , Subject: [PATCH v2] x86/purgatory: Remove LTO flags Date: Fri, 8 Sep 2023 16:12:44 -0700 Message-ID: <20230908231244.1092614-1-song@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: jg41T-4l24zQ1yAN3q4KewC_oaCjHY6p X-Proofpoint-ORIG-GUID: jg41T-4l24zQ1yAN3q4KewC_oaCjHY6p X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.957,Hydra:6.0.601,FMLib:17.11.176.26 definitions=2023-09-08_18,2023-09-05_01,2023-05-22_02 X-Spam-Status: No, score=-1.6 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1776519174461770110 X-GMAIL-MSGID: 1776577926745698684 With LTO enabled, ld.lld generates multiple .text sections for purgatory.ro: $ readelf -S purgatory.ro | grep " .text" [ 1] .text PROGBITS 0000000000000000 00000040 [ 7] .text.purgatory PROGBITS 0000000000000000 000020e0 [ 9] .text.warn PROGBITS 0000000000000000 000021c0 [13] .text.sha256_upda PROGBITS 0000000000000000 000022f0 [15] .text.sha224_upda PROGBITS 0000000000000000 00002be0 [17] .text.sha256_fina PROGBITS 0000000000000000 00002bf0 [19] .text.sha224_fina PROGBITS 0000000000000000 00002cc0 This cause WARNING from kexec_purgatory_setup_sechdrs(): WARNING: CPU: 26 PID: 110894 at kernel/kexec_file.c:919 kexec_load_purgatory+0x37f/0x390 Fix this by disabling LTO for purgatory. Fixes: 8652d44f466a ("kexec: support purgatories with .text.hot sections") Cc: Ricardo Ribalda Cc: Sami Tolvanen Cc: kexec@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: x86@kernel.org Cc: llvm@lists.linux.dev Signed-off-by: Song Liu --- AFAICT, x86 is the only arch that supports LTO and purgatory. Changes in v2: 1. Use CC_FLAGS_LTO instead of hardcode -flto. (Nick Desaulniers) --- arch/x86/purgatory/Makefile | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/purgatory/Makefile b/arch/x86/purgatory/Makefile index c2a29be35c01..08aa0f25f12a 100644 --- a/arch/x86/purgatory/Makefile +++ b/arch/x86/purgatory/Makefile @@ -19,6 +19,10 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS -D__NO_FORTIFY # optimization flags. KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS)) +# When LTO is enabled, llvm emits many text sections, which is not supported +# by kexec. Remove -flto=* flags. +KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO),$(KBUILD_CFLAGS)) + # When linking purgatory.ro with -r unresolved symbols are not checked, # also link a purgatory.chk binary without -r to check for unresolved symbols. PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib