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=-13.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 CE695C43387 for ; Tue, 8 Jan 2019 19:53:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C82520827 for ; Tue, 8 Jan 2019 19:53:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546977223; bh=xAxDl5gVabg/8waNC08baTXxsRCiq5C57RZnnEqhLbA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=F4sLu6HEvt0uWITo/hmzTrf+VktSCE51V+/kLr0IH5RUdOOV8bhFv0UxfsGZ/vDs/ StG+iPRDKmPtBGMcFM7kJxdps7U+/mpwrufzQD4tKzDtZrKE7XvvXlMVBQ8/QsRCvK dnP1IQ8jxKuPP4UOlwWBWfOwsQIo9vK4tn7jOBjc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731444AbfAHTxm (ORCPT ); Tue, 8 Jan 2019 14:53:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:38828 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730193AbfAHTa4 (ORCPT ); Tue, 8 Jan 2019 14:30:56 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 104122070B; Tue, 8 Jan 2019 19:30:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546975855; bh=xAxDl5gVabg/8waNC08baTXxsRCiq5C57RZnnEqhLbA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2XwzFX3jQSAEZSo8Y8asE8f0gNC2K1Ofnu/KwQwAOqi6OxjbXEDfcLQ198rn0JRlV 7cwLY21MmVhH61yDFs3gywKXTKLiTZHD6D1ngX/zKVsFACsD88fkXsNG6GcHGFo7Ou prK8ShCqdrzPVz5iusX1kFOxe5g29w0etvPwGFAc= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ard Biesheuvel , Nick Desaulniers , Peter Smith , Will Deacon , Sasha Levin Subject: [PATCH AUTOSEL 4.19 39/97] arm64: relocatable: fix inconsistencies in linker script and options Date: Tue, 8 Jan 2019 14:28:48 -0500 Message-Id: <20190108192949.122407-39-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190108192949.122407-1-sashal@kernel.org> References: <20190108192949.122407-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ard Biesheuvel [ Upstream commit 3bbd3db86470c701091fb1d67f1fab6621debf50 ] readelf complains about the section layout of vmlinux when building with CONFIG_RELOCATABLE=y (for KASLR): readelf: Warning: [21]: Link field (0) should index a symtab section. readelf: Warning: [21]: Info field (0) should index a relocatable section. Also, it seems that our use of '-pie -shared' is contradictory, and thus ambiguous. In general, the way KASLR is wired up at the moment is highly tailored to how ld.bfd happens to implement (and conflate) PIE executables and shared libraries, so given the current effort to support other toolchains, let's fix some of these issues as well. - Drop the -pie linker argument and just leave -shared. In ld.bfd, the differences between them are unclear (except for the ELF type of the produced image [0]) but lld chokes on seeing both at the same time. - Rename the .rela output section to .rela.dyn, as is customary for shared libraries and PIE executables, so that it is not misidentified by readelf as a static relocation section (producing the warnings above). - Pass the -z notext and -z norelro options to explicitly instruct the linker to permit text relocations, and to omit the RELRO program header (which requires a certain section layout that we don't adhere to in the kernel). These are the defaults for current versions of ld.bfd. - Discard .eh_frame and .gnu.hash sections to avoid them from being emitted between .head.text and .text, screwing up the section layout. These changes only affect the ELF image, and produce the same binary image. [0] b9dce7f1ba01 ("arm64: kernel: force ET_DYN ELF type for ...") Cc: Nick Desaulniers Cc: Peter Smith Tested-by: Nick Desaulniers Signed-off-by: Ard Biesheuvel Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/Makefile | 2 +- arch/arm64/kernel/vmlinux.lds.S | 9 +++++---- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 106039d25e2f..35649ee8ad56 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -18,7 +18,7 @@ ifeq ($(CONFIG_RELOCATABLE), y) # Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour # for relative relocs, since this leads to better Image compression # with the relocation offsets always being zero. -LDFLAGS_vmlinux += -pie -shared -Bsymbolic \ +LDFLAGS_vmlinux += -shared -Bsymbolic -z notext -z norelro \ $(call ld-option, --no-apply-dynamic-relocs) endif diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 605d1b60469c..74e469f8a850 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -99,7 +99,8 @@ SECTIONS *(.discard) *(.discard.*) *(.interp .dynamic) - *(.dynsym .dynstr .hash) + *(.dynsym .dynstr .hash .gnu.hash) + *(.eh_frame) } . = KIMAGE_VADDR + TEXT_OFFSET; @@ -176,12 +177,12 @@ SECTIONS PERCPU_SECTION(L1_CACHE_BYTES) - .rela : ALIGN(8) { + .rela.dyn : ALIGN(8) { *(.rela .rela*) } - __rela_offset = ABSOLUTE(ADDR(.rela) - KIMAGE_VADDR); - __rela_size = SIZEOF(.rela); + __rela_offset = ABSOLUTE(ADDR(.rela.dyn) - KIMAGE_VADDR); + __rela_size = SIZEOF(.rela.dyn); . = ALIGN(SEGMENT_ALIGN); __initdata_end = .; -- 2.19.1