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=-10.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_MED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 DA170C43142 for ; Mon, 25 Jun 2018 22:41:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 845D226210 for ; Mon, 25 Jun 2018 22:41:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ARK9ftcg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 845D226210 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934189AbeFYWla (ORCPT ); Mon, 25 Jun 2018 18:41:30 -0400 Received: from mail-io0-f202.google.com ([209.85.223.202]:49719 "EHLO mail-io0-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933969AbeFYWl0 (ORCPT ); Mon, 25 Jun 2018 18:41:26 -0400 Received: by mail-io0-f202.google.com with SMTP id x13-v6so12887215iog.16 for ; Mon, 25 Jun 2018 15:41:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:date:in-reply-to:message-id:references:subject:from:to :cc; bh=XXQ7C/CDeUMNvwwGw/8BYZVCFy2rI+v0Pigd08BAKSc=; b=ARK9ftcgOouSqk4fMxtyYsAfDex24/Ayzi/AtIxioDUezvChXudQkPfNOwwr+3ZiRL rVCwh5esMjB9OTMkdaqfam+0w2pfO9aYrBUYX40KkiohWcjVjigpRkTishZWQzBBP/uR 1ql786ng1WWfmkMjPO+FuSQfa1Z8UX34oKUUlsqe4cgFd2+9/+o8WiI19h/3a7pxOjwq MV/8m0KQdewBL4Q8AxKONCqHduy0eq5ZMhWTYJCpe6G/2I6BDldafG5NTvKRJKKHG4vX WhBbWMi5LPECGI+m2D0C2JNvVV08sSEH0TwU3YdQ8uhlfO7wtw83EhJ8/LD3yQCr9Jp7 060g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:date:in-reply-to:message-id :references:subject:from:to:cc; bh=XXQ7C/CDeUMNvwwGw/8BYZVCFy2rI+v0Pigd08BAKSc=; b=j9bW7+hp0r/ranvT5ZNkitWCu9uwwNfwHUg2cvWL0rc3/YTgygcA+qTaLkvwKHF+b8 TEvBiBgppqtxBZRxRQloG8mC9NOvYz/RHDd2P1icsnE5fkm4oS9+HFbKMFJ5b/h14mpV 1NsfOM7hufzA1VXZvVoTLeOOuREb1mwb81+zZEwLhlC8j4zQatnx09XzRSmcQ4Ln/TKR rdEgEwQe1oPufVvdX2J+ofnBT4IO7y8hRwtrQsw26bdD7YI1Hdc8kbQyHx3+dNK89ERV /QX2L2PONWX6lLzVZWuWcBkkHdygT0iHzUvBdwRD+sgRlGetwZE0UzrFB192JWIcqiif Hsng== X-Gm-Message-State: APt69E2TpNSfI5sc7A4FMGgbuAErrc5Rlr+fI8czhS+NlHNYIbF5HmCV VrlEJ5kiysrt+9rDwzyO72IH0n/sNe2/Dg== X-Google-Smtp-Source: ADUXVKInHsu2npYg7XtQ4k9TVhn2iNrTC4MpiIVgLdoBMmCL8Nj9iE/HXeNOjEeLLnh2WsEB9e3brWOFXptFRg== MIME-Version: 1.0 X-Received: by 2002:a24:14ca:: with SMTP id 193-v6mr1231065itg.13.1529966485494; Mon, 25 Jun 2018 15:41:25 -0700 (PDT) Date: Mon, 25 Jun 2018 15:38:58 -0700 In-Reply-To: <20180625224014.134829-1-thgarnie@google.com> Message-Id: <20180625224014.134829-11-thgarnie@google.com> References: <20180625224014.134829-1-thgarnie@google.com> X-Mailer: git-send-email 2.18.0.rc2.346.g013aa6912e-goog Subject: [PATCH v5 10/27] x86/boot/64: Adapt assembly for PIE support From: Thomas Garnier To: kernel-hardening@lists.openwall.com Cc: Thomas Garnier , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Josh Poimboeuf , "Kirill A. Shutemov" , Borislav Petkov , Dave Hansen , Tom Lendacky , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Change the assembly code to use only relative references of symbols for the kernel to be PIE compatible. Early at boot, the kernel is mapped at a temporary address while preparing the page table. To know the changes needed for the page table with KASLR, the boot code calculate the difference between the expected address of the kernel and the one chosen by KASLR. It does not work with PIE because all symbols in code are relatives. Instead of getting the future relocated virtual address, you will get the current temporary mapping. Instructions were changed to have absolute 64-bit references. Position Independent Executable (PIE) support will allow to extend the KASLR randomization range 0xffffffff80000000. Signed-off-by: Thomas Garnier --- arch/x86/kernel/head_64.S | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 8344dd2f310a..7fca19e1f556 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -89,8 +89,10 @@ startup_64: popq %rsi /* Form the CR3 value being sure to include the CR3 modifier */ - addq $(early_top_pgt - __START_KERNEL_map), %rax + movabs $(early_top_pgt - __START_KERNEL_map), %rcx + addq %rcx, %rax jmp 1f + ENTRY(secondary_startup_64) UNWIND_HINT_EMPTY /* @@ -119,7 +121,8 @@ ENTRY(secondary_startup_64) popq %rsi /* Form the CR3 value being sure to include the CR3 modifier */ - addq $(init_top_pgt - __START_KERNEL_map), %rax + movabs $(init_top_pgt - __START_KERNEL_map), %rcx + addq %rcx, %rax 1: /* Enable PAE mode, PGE and LA57 */ @@ -137,7 +140,7 @@ ENTRY(secondary_startup_64) movq %rax, %cr3 /* Ensure I am executing from virtual addresses */ - movq $1f, %rax + movabs $1f, %rax ANNOTATE_RETPOLINE_SAFE jmp *%rax 1: @@ -234,11 +237,12 @@ ENTRY(secondary_startup_64) * REX.W + FF /5 JMP m16:64 Jump far, absolute indirect, * address given in m16:64. */ - pushq $.Lafter_lret # put return address on stack for unwinder + movabs $.Lafter_lret, %rax + pushq %rax # put return address on stack for unwinder xorq %rbp, %rbp # clear frame pointer - movq initial_code(%rip), %rax + leaq initial_code(%rip), %rax pushq $__KERNEL_CS # set correct cs - pushq %rax # target address in negative space + pushq (%rax) # target address in negative space lretq .Lafter_lret: END(secondary_startup_64) -- 2.18.0.rc2.346.g013aa6912e-goog