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=-13.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 C7D3FC433F4 for ; Fri, 24 Jul 2020 16:04:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE7AF20674 for ; Fri, 24 Jul 2020 16:04:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727933AbgGXQE3 (ORCPT ); Fri, 24 Jul 2020 12:04:29 -0400 Received: from 8bytes.org ([81.169.241.247]:59420 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727834AbgGXQEV (ORCPT ); Fri, 24 Jul 2020 12:04:21 -0400 Received: from cap.home.8bytes.org (p5b006776.dip0.t-ipconnect.de [91.0.103.118]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by theia.8bytes.org (Postfix) with ESMTPSA id 8D88EFB8; Fri, 24 Jul 2020 18:04:12 +0200 (CEST) From: Joerg Roedel To: x86@kernel.org Cc: Joerg Roedel , Joerg Roedel , hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Sean Christopherson , Martin Radev , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH v5 30/75] x86/head/64: Setup MSR_GS_BASE before calling into C code Date: Fri, 24 Jul 2020 18:02:51 +0200 Message-Id: <20200724160336.5435-31-joro@8bytes.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200724160336.5435-1-joro@8bytes.org> References: <20200724160336.5435-1-joro@8bytes.org> 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: Joerg Roedel When stack-protector is enabled a valid GS_BASE is needed before calling any C code function, because the stack canary is loaded from per-cpu data. Signed-off-by: Joerg Roedel --- arch/x86/kernel/head64.c | 7 +++++++ arch/x86/kernel/head_64.S | 8 ++++++++ 2 files changed, 15 insertions(+) diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 8c82be44be94..b0ab5627900b 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -36,6 +36,7 @@ #include #include #include +#include /* * Manage page tables very early on. @@ -513,6 +514,8 @@ void __init x86_64_start_reservations(char *real_mode_data) */ void __head startup_64_setup_env(unsigned long physbase) { + unsigned long gsbase; + /* Load GDT */ startup_gdt_descr.address = (unsigned long)fixup_pointer(startup_gdt, physbase); native_load_gdt(&startup_gdt_descr); @@ -521,4 +524,8 @@ void __head startup_64_setup_env(unsigned long physbase) asm volatile("movl %%eax, %%ds\n" "movl %%eax, %%ss\n" "movl %%eax, %%es\n" : : "a"(__KERNEL_DS) : "memory"); + + /* Setup GS_BASE - needed for stack protector */ + gsbase = (unsigned long)fixup_pointer((void *)initial_gs, physbase); + __wrmsr(MSR_GS_BASE, (u32)gsbase, (u32)(gsbase >> 32)); } diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 2b2e91627221..800053219054 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -78,6 +78,14 @@ SYM_CODE_START_NOALIGN(startup_64) call startup_64_setup_env popq %rsi + /* + * Setup %gs here already to make stack-protector work - it needs to be + * setup again after the switch to kernel addresses. The address read + * from initial_gs is a kernel address, so it needs to be adjusted first + * for the identity mapping. + */ + movl $MSR_GS_BASE,%ecx + /* Now switch to __KERNEL_CS so IRET works reliably */ pushq $__KERNEL_CS leaq .Lon_kernel_cs(%rip), %rax -- 2.27.0