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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 9C784C43387 for ; Fri, 11 Jan 2019 20:10:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 749002133F for ; Fri, 11 Jan 2019 20:10:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=android.com header.i=@android.com header.b="HFVRz+8p" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390638AbfAKUK2 (ORCPT ); Fri, 11 Jan 2019 15:10:28 -0500 Received: from mail-pg1-f193.google.com ([209.85.215.193]:38229 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388761AbfAKUK2 (ORCPT ); Fri, 11 Jan 2019 15:10:28 -0500 Received: by mail-pg1-f193.google.com with SMTP id g189so6753663pgc.5 for ; Fri, 11 Jan 2019 12:10:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=android.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=N2t2CkOAm8FQ5aserNlV4RpNfw0q7c3zGmUG3z9KhEM=; b=HFVRz+8pHY5br+co8CLV5eogPIABPb0HgDM6TJ9MupONRsZe4K3ePAMZTZusTp0oj+ uT/IAIN7HL0Hg7PwR5t3x9wBJ9d/lX+VitXPsexDN2pCzItameO9zDdiVjG3JFUuRMIJ TfWdQUKwVEgZmNzn/930fgJs4K62qGj2V5JcvBK4Eha+qXXpjsVOo4dg9yzKd7ukO23i pyostSxlpoERcplNMqv8d70UXNMhWaiXCx7n2oDZFfHtob/uxfjqjj2bM3fo4H3iey5z mEm17LwKY+MfZ+oopO0qASY36KTf7FXdKxaOIP+fPXnByMDne8T1BYp6mR7xzNrqYZxQ bsfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=N2t2CkOAm8FQ5aserNlV4RpNfw0q7c3zGmUG3z9KhEM=; b=kAd3sCNr4PtwXtQWpkv1x4ruGouyqSRxkvjsLXY8zVeoNYTxuuiPlm1rzZ1V3GOWK4 ZVyLsyjv0Eg0gf6TnPQqG5ITGu2tWg4fgqenmrbFggDNFH1Uzs+hJGeDttoa9ZH+JG5f PdOPQesmo5FVQRdW3vkbsvf51RXfNKEb0mHowsqm8hfaW8H9C+GBceYuTboZRDSTDEeu dQ0LprB3gwo+3tp+SEuOlGcADYZ+37Lb7/G8kM8885hIvgwVFo8y4uJgFG1S11uoE8Z6 Voy949p5wwJwt5xIUnlYXbKqoXRfro+HNYnG5lqqAupeL90w4TLu9dmjNWz4RqRwwiFM 5uHA== X-Gm-Message-State: AJcUukfBbRoDRvkicR1khTuim/p6tGhI4bzELoP/skHJIVXBS5VHC1Iq ENrZRePuMTvqMviZsUR8rBGxcQ== X-Google-Smtp-Source: ALg8bN4ZMGrtC+D6keTcE5kPQRaPOL1nBKqWX51cLcR/iOGYCHIPsMKL4oZv3jVPSr8K5oy7szVNEA== X-Received: by 2002:a63:c503:: with SMTP id f3mr14204907pgd.431.1547237426713; Fri, 11 Jan 2019 12:10:26 -0800 (PST) Received: from trong0.mtv.corp.google.com ([2620:0:1000:1601:c43f:8c1b:f6ef:3dce]) by smtp.gmail.com with ESMTPSA id l185sm117201899pfl.54.2019.01.11.12.10.25 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 11 Jan 2019 12:10:26 -0800 (PST) From: Tri Vo To: x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com Cc: grimar@accesssoftek.com, dima@golovin.in, morbo@google.com, ndesaulniers@google.com, matz@suse.de, ruiu@google.com, linux-kernel@vger.kernel.org, Tri Vo Subject: [PATCH v3] x86_64: Add "-m elf_i386" when linking i386 object files. Date: Fri, 11 Jan 2019 12:10:12 -0800 Message-Id: <20190111201012.71210-1-trong@android.com> X-Mailer: git-send-email 2.20.1.97.g81188d93c3-goog In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: George Rimar Linux kernel uses OUTPUT_FORMAT in it's linker scripts. Most of the time -m option is passed to the linker with correct architecture, but sometimes (at least for x86_64) the -m option contradicts OUTPUT_FORMAT directive. Specifically, arch/x86/boot and arch/x86/realmode/rm modules have i386 object files, but are linked with -m elf_x86_64 linker flag when building for x86_64. "man ld" doesn't explicitly state any tie-breakers between -m and OUTPUT_FORMAT. BFD and Gold linkers override -m value with OUTPUT_FORMAT. But LLVM lld has a different behavior. When supplied with contradicting -m and OUTPUT_FORMAT values it fails with the following error message: ld.lld: error: arch/x86/realmode/rm/header.o is incompatible with elf_x86_64 Suggested fix: just add correct -m after incorrect one (it overrides it), so the linker invocation looks like this: ld -m elf_x86_64 -z max-page-size=0x200000 -m elf_i386 --emit-relocs -T realmode.lds header.o trampoline_64.o stack.o reboot.o -o realmode.elf This is not a functional change for GNU ld, because (although not explicitly documented) it already overrides -m EMULATION with OUTPUT_FORMAT. Tested by building x86_64 kernel with GNU gcc/ld toolchain and booting it in QEMU. Suggested-by: Dmitry Golovin Signed-off-by: George Rimar Signed-off-by: Tri Vo Tested-by: Tri Vo Tested-by: Nick Desaulniers --- v2: updated commit message to clarify that ld documentation is ambiguous w.r.t -m vs OUTPUT_FORMAT behavior. v3: fixed/added SOB and "Tested-by" fields. arch/x86/boot/Makefile | 2 +- arch/x86/realmode/rm/Makefile | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile index 9b5adae9cc40..e2839b5c246c 100644 --- a/arch/x86/boot/Makefile +++ b/arch/x86/boot/Makefile @@ -100,7 +100,7 @@ $(obj)/zoffset.h: $(obj)/compressed/vmlinux FORCE AFLAGS_header.o += -I$(objtree)/$(obj) $(obj)/header.o: $(obj)/zoffset.h -LDFLAGS_setup.elf := -T +LDFLAGS_setup.elf := -m elf_i386 -T $(obj)/setup.elf: $(src)/setup.ld $(SETUP_OBJS) FORCE $(call if_changed,ld) diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile index 4463fa72db94..96cb20de08af 100644 --- a/arch/x86/realmode/rm/Makefile +++ b/arch/x86/realmode/rm/Makefile @@ -47,7 +47,7 @@ $(obj)/pasyms.h: $(REALMODE_OBJS) FORCE targets += realmode.lds $(obj)/realmode.lds: $(obj)/pasyms.h -LDFLAGS_realmode.elf := --emit-relocs -T +LDFLAGS_realmode.elf := -m elf_i386 --emit-relocs -T CPPFLAGS_realmode.lds += -P -C -I$(objtree)/$(obj) targets += realmode.elf -- 2.20.1.97.g81188d93c3-goog