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,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 867C4C43387 for ; Tue, 8 Jan 2019 19:46:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 537D42063F for ; Tue, 8 Jan 2019 19:46:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546976817; bh=OXxvn0OaptjFeg1jchr9B7WnvuREIkoQyP0OfUm8VAQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=QLAuvpPczAUbqUX+bUzP0415TfGAWT1WZ5KEN/m4eZA92jZ7OIf/UedLJ+GVvD6ZR dUSsW5N5Sq4LiyT4jdkka+t0uZZepwptYwFQ2wmpgoWY0ZYYMdc0JhKFgU8aWeDoFE lpCxqcHxstBSYXJ8pznZNs0gw9IQv1XW8Syds9wk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732743AbfAHTq4 (ORCPT ); Tue, 8 Jan 2019 14:46:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:41762 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731513AbfAHTc7 (ORCPT ); Tue, 8 Jan 2019 14:32:59 -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 71C832063F; Tue, 8 Jan 2019 19:32:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1546975978; bh=OXxvn0OaptjFeg1jchr9B7WnvuREIkoQyP0OfUm8VAQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jD+q6k5z9XslSRXniSbCSKitx3Wsvx+Io29lYU2vBuCHNLXfLfbXeimcOmhFjpvQL rSIVLkmVnmxbi4qORsBil29s6nYuR+RfKEZfRBTXr5EJY5X1Y6J5AWavCQdsHXhqUM cf167RsPza9SdMbVnBjnvTa8RpVifX3R7DjiO/r8= 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 4.14 20/53] arm64: relocatable: fix inconsistencies in linker script and options Date: Tue, 8 Jan 2019 14:31:48 -0500 Message-Id: <20190108193222.123316-20-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190108193222.123316-1-sashal@kernel.org> References: <20190108193222.123316-1-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 48f2b3657507..0c5f70e6d5cf 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 ddfd3c0942f7..6edfdf5b061d 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