From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E62A6FD0 for ; Fri, 8 Sep 2023 23:13:05 +0000 (UTC) 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 388HqD5F030687 for ; Fri, 8 Sep 2023 16:13:04 -0700 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3t06jvvkdt-4 (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::11) 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 Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-GUID: bMJrZCuQPwxkV4xW8nbyWnvtNtaWehqN X-Proofpoint-ORIG-GUID: bMJrZCuQPwxkV4xW8nbyWnvtNtaWehqN 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 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 :=3D -D__DISABLE_EXPORTS -D__NO_FORTIF= Y # optimization flags. KBUILD_CFLAGS :=3D $(filter-out -fprofile-sample-use=3D% -fprofile-use=3D= %,$(KBUILD_CFLAGS)) =20 +# When LTO is enabled, llvm emits many text sections, which is not suppo= rted +# by kexec. Remove -flto=3D* flags. +KBUILD_CFLAGS :=3D $(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 sy= mbols. PURGATORY_LDFLAGS :=3D -e purgatory_start -z nodefaultlib --=20 2.34.1