From patchwork Mon Mar 15 13:56:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 401152 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, 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 CAE5EC4332D for ; Mon, 15 Mar 2021 14:10:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A0DF464F10 for ; Mon, 15 Mar 2021 14:10:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234671AbhCOOJx (ORCPT ); Mon, 15 Mar 2021 10:09:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:52484 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234592AbhCOOE1 (ORCPT ); Mon, 15 Mar 2021 10:04:27 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3608464EE3; Mon, 15 Mar 2021 14:04:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1615817064; bh=zkW3X2cjuHyAapqmSQFKgFaH8zGEnwvw4p/lYgJa3kc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=THUTm2s1yR9EIbYBUm1nJhq++S58lossXtcdChNqkZ5nZKbMCmkjfGCfbwCk5uh8o uNKwR53GU9Qo3wMeH7DoJomlbr/zc1nO+Dsn9DgiU2CnsMg0/v6DanepvlXV1FAXUl IkfkpP98abxEIR7EuMDI8DeqxUUhZGQJBCpRylQo= From: gregkh@linuxfoundation.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Joerg Roedel , Borislav Petkov Subject: [PATCH 5.10 270/290] x86/sev-es: Introduce ip_within_syscall_gap() helper Date: Mon, 15 Mar 2021 14:56:03 +0100 Message-Id: <20210315135551.141688745@linuxfoundation.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210315135541.921894249@linuxfoundation.org> References: <20210315135541.921894249@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Greg Kroah-Hartman From: Joerg Roedel commit 78a81d88f60ba773cbe890205e1ee67f00502948 upstream. Introduce a helper to check whether an exception came from the syscall gap and use it in the SEV-ES code. Extend the check to also cover the compatibility SYSCALL entry path. Fixes: 315562c9af3d5 ("x86/sev-es: Adjust #VC IST Stack on entering NMI handler") Signed-off-by: Joerg Roedel Signed-off-by: Borislav Petkov Cc: stable@vger.kernel.org # 5.10+ Link: https://lkml.kernel.org/r/20210303141716.29223-2-joro@8bytes.org Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/entry_64_compat.S | 2 ++ arch/x86/include/asm/proto.h | 1 + arch/x86/include/asm/ptrace.h | 15 +++++++++++++++ arch/x86/kernel/traps.c | 3 +-- 4 files changed, 19 insertions(+), 2 deletions(-) --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -210,6 +210,8 @@ SYM_CODE_START(entry_SYSCALL_compat) /* Switch to the kernel stack */ movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp +SYM_INNER_LABEL(entry_SYSCALL_compat_safe_stack, SYM_L_GLOBAL) + /* Construct struct pt_regs on stack */ pushq $__USER32_DS /* pt_regs->ss */ pushq %r8 /* pt_regs->sp */ --- a/arch/x86/include/asm/proto.h +++ b/arch/x86/include/asm/proto.h @@ -25,6 +25,7 @@ void __end_SYSENTER_singlestep_region(vo void entry_SYSENTER_compat(void); void __end_entry_SYSENTER_compat(void); void entry_SYSCALL_compat(void); +void entry_SYSCALL_compat_safe_stack(void); void entry_INT80_compat(void); #ifdef CONFIG_XEN_PV void xen_entry_INT80_compat(void); --- a/arch/x86/include/asm/ptrace.h +++ b/arch/x86/include/asm/ptrace.h @@ -94,6 +94,8 @@ struct pt_regs { #include #endif +#include + struct cpuinfo_x86; struct task_struct; @@ -175,6 +177,19 @@ static inline bool any_64bit_mode(struct #ifdef CONFIG_X86_64 #define current_user_stack_pointer() current_pt_regs()->sp #define compat_user_stack_pointer() current_pt_regs()->sp + +static inline bool ip_within_syscall_gap(struct pt_regs *regs) +{ + bool ret = (regs->ip >= (unsigned long)entry_SYSCALL_64 && + regs->ip < (unsigned long)entry_SYSCALL_64_safe_stack); + +#ifdef CONFIG_IA32_EMULATION + ret = ret || (regs->ip >= (unsigned long)entry_SYSCALL_compat && + regs->ip < (unsigned long)entry_SYSCALL_compat_safe_stack); +#endif + + return ret; +} #endif static inline unsigned long kernel_stack_pointer(struct pt_regs *regs) --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -686,8 +686,7 @@ asmlinkage __visible noinstr struct pt_r * In the SYSCALL entry path the RSP value comes from user-space - don't * trust it and switch to the current kernel stack */ - if (regs->ip >= (unsigned long)entry_SYSCALL_64 && - regs->ip < (unsigned long)entry_SYSCALL_64_safe_stack) { + if (ip_within_syscall_gap(regs)) { sp = this_cpu_read(cpu_current_top_of_stack); goto sync; }