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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,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 E733EC83000 for ; Tue, 28 Apr 2020 15:22:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF9D52186A for ; Tue, 28 Apr 2020 15:22:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728847AbgD1PWv (ORCPT ); Tue, 28 Apr 2020 11:22:51 -0400 Received: from 8bytes.org ([81.169.241.247]:37386 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728263AbgD1PSD (ORCPT ); Tue, 28 Apr 2020 11:18:03 -0400 Received: by theia.8bytes.org (Postfix, from userid 1000) id E526AF0E; Tue, 28 Apr 2020 17:17:47 +0200 (CEST) From: Joerg Roedel To: x86@kernel.org Cc: hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Thomas Hellstrom , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Joerg Roedel , Joerg Roedel , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH v3 31/75] x86/head/64: Install boot GDT Date: Tue, 28 Apr 2020 17:16:41 +0200 Message-Id: <20200428151725.31091-32-joro@8bytes.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200428151725.31091-1-joro@8bytes.org> References: <20200428151725.31091-1-joro@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joerg Roedel Handling exceptions during boot requires a working GDT. The kernel GDT is not yet ready for use, so install a temporary boot GDT. Signed-off-by: Joerg Roedel --- arch/x86/kernel/head_64.S | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 4bbc770af632..11a28c1fb51f 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -72,6 +72,26 @@ SYM_CODE_START_NOALIGN(startup_64) /* Set up the stack for verify_cpu(), similar to initial_stack below */ leaq (__end_init_task - SIZEOF_PTREGS)(%rip), %rsp + /* Setup boot GDT descriptor and load boot GDT */ + leaq boot_gdt(%rip), %rax + movq %rax, boot_gdt_base(%rip) + lgdt boot_gdt_descr(%rip) + + /* New GDT is live - reload data segment registers */ + movl $__KERNEL_DS, %eax + movl %eax, %ds + movl %eax, %ss + movl %eax, %es + + /* Now switch to __KERNEL_CS so IRET works reliably */ + pushq $__KERNEL_CS + leaq .Lon_kernel_cs(%rip), %rax + pushq %rax + lretq + +.Lon_kernel_cs: + UNWIND_HINT_EMPTY + /* Sanitize CPU configuration */ call verify_cpu @@ -480,6 +500,22 @@ SYM_DATA_LOCAL(early_gdt_descr_base, .quad INIT_PER_CPU_VAR(gdt_page)) SYM_DATA(phys_base, .quad 0x0) EXPORT_SYMBOL(phys_base) +/* Boot GDT used when kernel addresses are not mapped yet */ +SYM_DATA_LOCAL(boot_gdt_descr, .word boot_gdt_end - boot_gdt) +SYM_DATA_LOCAL(boot_gdt_base, .quad 0) +SYM_DATA_START(boot_gdt) + .quad 0 + .quad 0x00cf9a000000ffff /* __KERNEL32_CS */ + .quad 0x00af9a000000ffff /* __KERNEL_CS */ + .quad 0x00cf92000000ffff /* __KERNEL_DS */ + .quad 0 /* __USER32_CS - unused */ + .quad 0 /* __USER_DS - unused */ + .quad 0 /* __USER_CS - unused */ + .quad 0 /* unused */ + .quad 0x0080890000000000 /* TSS descriptor */ + .quad 0x0000000000000000 /* TSS continued */ +SYM_DATA_END_LABEL(boot_gdt, SYM_L_LOCAL, boot_gdt_end) + #include "../../x86/xen/xen-head.S" __PAGE_ALIGNED_BSS -- 2.17.1