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, UNPARSEABLE_RELAY,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 77E37C433E1 for ; Tue, 26 May 2020 04:35:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F1FC207FB for ; Tue, 26 May 2020 04:35:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726690AbgEZEfS (ORCPT ); Tue, 26 May 2020 00:35:18 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:60945 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726380AbgEZEfR (ORCPT ); Tue, 26 May 2020 00:35:17 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R771e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e07488;MF=laijs@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0TzgeTgw_1590467713; Received: from localhost(mailfrom:laijs@linux.alibaba.com fp:SMTPD_---0TzgeTgw_1590467713) by smtp.aliyun-inc.com(127.0.0.1); Tue, 26 May 2020 12:35:13 +0800 From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: Lai Jiangshan , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" Subject: [PATCH 2/2] x86/entry: always flush user CR3 in RESTORE_CR3 Date: Tue, 26 May 2020 04:35:07 +0000 Message-Id: <20200526043507.51977-3-laijs@linux.alibaba.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200526043507.51977-1-laijs@linux.alibaba.com> References: <20200526043507.51977-1-laijs@linux.alibaba.com> 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 RESTORE_CR3 is called when CPL==0 or #DF, it is unlikely CPL==0&cr3==userCR3 and #DF itself is unlikely case. There is no much overhead to always flush userCR3. Signed-off-by: Lai Jiangshan --- arch/x86/entry/calling.h | 27 ++++++--------------------- arch/x86/entry/entry_64.S | 6 +++--- 2 files changed, 9 insertions(+), 24 deletions(-) diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index 505246185624..ff26e4eb7063 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -265,33 +265,18 @@ For 32-bit we have the following conventions - kernel is built with .Ldone_\@: .endm -.macro RESTORE_CR3 scratch_reg:req save_reg:req +.macro RESTORE_CR3 save_reg:req ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_PTI /* * Skip resuming KERNEL pages since it is already KERNEL CR3. + * + * RESTORE_CR3 is called when CPL==0 or #DF, it is unlikely + * CPL==0&cr3==userCR3 and #DF itself is unlikely case. + * There is no much overhead to always flush userCR3. */ bt $PTI_USER_PGTABLE_BIT, \save_reg jnc .Lend_\@ - - ALTERNATIVE "jmp .Lwrcr3_\@", "", X86_FEATURE_PCID - - /* - * Check if there's a pending flush for the user ASID we're - * about to set. - */ - movq \save_reg, \scratch_reg - andq $(0x7FF), \scratch_reg - bt \scratch_reg, THIS_CPU_user_pcid_flush_mask - jnc .Lnoflush_\@ - - btr \scratch_reg, THIS_CPU_user_pcid_flush_mask - jmp .Lwrcr3_\@ - -.Lnoflush_\@: - SET_NOFLUSH_BIT \save_reg - -.Lwrcr3_\@: movq \save_reg, %cr3 .Lend_\@: .endm @@ -306,7 +291,7 @@ For 32-bit we have the following conventions - kernel is built with .endm .macro SAVE_AND_SWITCH_TO_KERNEL_CR3 scratch_reg:req save_reg:req .endm -.macro RESTORE_CR3 scratch_reg:req save_reg:req +.macro RESTORE_CR3 save_reg:req .endm #endif diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index d983a0d4bc73..46efa842a45e 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1283,13 +1283,13 @@ SYM_CODE_START_LOCAL(paranoid_exit) jnz .Lparanoid_exit_no_swapgs TRACE_IRQS_IRETQ /* Always restore stashed CR3 value (see paranoid_entry) */ - RESTORE_CR3 scratch_reg=%rbx save_reg=%r14 + RESTORE_CR3 save_reg=%r14 SWAPGS_UNSAFE_STACK jmp restore_regs_and_return_to_kernel .Lparanoid_exit_no_swapgs: TRACE_IRQS_IRETQ_DEBUG /* Always restore stashed CR3 value (see paranoid_entry) */ - RESTORE_CR3 scratch_reg=%rbx save_reg=%r14 + RESTORE_CR3 save_reg=%r14 jmp restore_regs_and_return_to_kernel SYM_CODE_END(paranoid_exit) @@ -1703,7 +1703,7 @@ end_repeat_nmi: call exc_nmi /* Always restore stashed CR3 value (see paranoid_entry) */ - RESTORE_CR3 scratch_reg=%r15 save_reg=%r14 + RESTORE_CR3 save_reg=%r14 testl %ebx, %ebx /* swapgs needed? */ jnz nmi_restore -- 2.20.1