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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B96D5C433FE for ; Wed, 11 May 2022 07:28:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243036AbiEKH2O (ORCPT ); Wed, 11 May 2022 03:28:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56682 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242956AbiEKH2H (ORCPT ); Wed, 11 May 2022 03:28:07 -0400 Received: from mail-pl1-x636.google.com (mail-pl1-x636.google.com [IPv6:2607:f8b0:4864:20::636]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CADAF3D483 for ; Wed, 11 May 2022 00:28:00 -0700 (PDT) Received: by mail-pl1-x636.google.com with SMTP id i1so1052736plg.7 for ; Wed, 11 May 2022 00:28:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=gkGEhy3VfxaC6VD1+0Znm8PQRe5Rv1gv7lzNV+9U6sU=; b=hOL2SmGEKUuNpF8//yrIHyFyW9QpHj5EcEyqSlL2j5Ss2Kk637E+sdDr1ipujizSp6 mBs3ISgZQuqdAdu6OMZ75YBdnojiygEvrhyLm+fc2iZzRtk4RIIOEbmWSMxqSmzEJ6iu 9mpCShLthHzj8HAPNuuxT5t9pJU5mrD9R70FEwFrqI+jpZbyrbhS/F9XNccIhoi7zerA qQwXXC5zyn6Q42wm1x+zxTMSLFzjR4NIBGUmXDMwlT7zDPQcWsWqPmllg0KrINWZE7Hh V3iBAJED+kr+y055flPWxxW2ORJHzR62PfxEpXLilu7+dZkR2JTPP+fr0ooi5+Up7Czy P7gA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=gkGEhy3VfxaC6VD1+0Znm8PQRe5Rv1gv7lzNV+9U6sU=; b=Eys4qDuBve7Qtgo/wCyWHnNzLu56oqPeegFAisMbeN62YUA8wbiho7astHTK21NiPs 7UrRmdIc3aVQo5DT8BBDUC08STEpuppiiAoQ4nRHHfWjkrpaXQPSPQUXnSdOAleIKcXD 5aU084/FuQ1P2fFdoO3t4d1Sp9gLrZ+RRq4sqsaYAcMhx8NO39hugvq8JnvY9/2n6bJ6 Kw8moap5DFiAb5eyfA/FC/nysdbuMylIeNyFo/o63vcuohpKQeSICoLUShCcYLLApsvA BHeZ4ILftsIJ042N9O/DpYBmL4wpKUUgm+YBdyfpvkn9SxprebS2OXcuodI/XlBNLR9F VfQg== X-Gm-Message-State: AOAM530jJBuFsqFtSvrgNgxqE0cGRY6Mu7/CIJwpAr+9Mjxivlo50EE8 mhz7Dy/YmznRyway2kGxwz0rpGUH/To= X-Google-Smtp-Source: ABdhPJyiupD//7dRtmU1nOj1/+hIdK289hdKppc2VOXLd8W9IyHJRVmAo9TXo3zE35ecQWZRa1cRVA== X-Received: by 2002:a17:90a:ec0e:b0:1d9:7f4d:23be with SMTP id l14-20020a17090aec0e00b001d97f4d23bemr3883921pjy.181.1652254080230; Wed, 11 May 2022 00:28:00 -0700 (PDT) Received: from localhost ([47.251.4.198]) by smtp.gmail.com with ESMTPSA id be12-20020a170902aa0c00b0015e8d4eb1e4sm954269plb.46.2022.05.11.00.27.59 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 May 2022 00:27:59 -0700 (PDT) From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: Borislav Petkov , Peter Zijlstra , Josh Poimboeuf , Andy Lutomirski , Thomas Gleixner , x86@kernel.org, Lai Jiangshan , Ingo Molnar , Dave Hansen , "H. Peter Anvin" Subject: [PATCH 6/7] x86/traps: Add fence_swapgs_{user,kernel}_entry() and user_entry_swapgs_and_fence() Date: Wed, 11 May 2022 15:27:46 +0800 Message-Id: <20220511072747.3960-7-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20220511072747.3960-1-jiangshanlai@gmail.com> References: <20220511072747.3960-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Lai Jiangshan Add the C version fence_swapgs_{user,kernel}_entry() in entry64.c which are the same as the ASM macro FENCE_SWAPGS_{USER,KERNEL}_ENTRY. fence_swapgs_user_entry is used in the user entry swapgs code path, to prevent a speculative swapgs when coming from kernel space. fence_swapgs_kernel_entry is used in the kernel entry code path, to prevent the swapgs from getting speculatively skipped when coming from user space. Add the C user_entry_swapgs_and_fence() which implements the ASM code: swapgs FENCE_SWAPGS_USER_ENTRY It will be used in the user entry swapgs code path, doing the swapgs and lfence to prevent a speculative swapgs when coming from kernel space. Cc: Josh Poimboeuf Suggested-by: Peter Zijlstra Signed-off-by: Lai Jiangshan --- arch/x86/entry/entry64.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/arch/x86/entry/entry64.c b/arch/x86/entry/entry64.c index bd77cc8373ce..f7f23800cee4 100644 --- a/arch/x86/entry/entry64.c +++ b/arch/x86/entry/entry64.c @@ -36,3 +36,33 @@ static __always_inline void switch_to_kernel_cr3(void) #else static __always_inline void switch_to_kernel_cr3(void) {} #endif + +/* + * Mitigate Spectre v1 for conditional swapgs code paths. + * + * fence_swapgs_user_entry is used in the user entry swapgs code path, to + * prevent a speculative swapgs when coming from kernel space. It must be + * used with switch_to_kernel_cr3() in the same path. + * + * fence_swapgs_kernel_entry is used in the kernel entry code path without + * CR3 write or with conditinal CR3 write only, to prevent the swapgs from + * getting speculatively skipped when coming from user space. + * + * user_entry_swapgs_and_fence is a wrapper of swapgs and fence for user entry + * code path. + */ +static __always_inline void fence_swapgs_user_entry(void) +{ + alternative("", "lfence", X86_FEATURE_FENCE_SWAPGS_USER); +} + +static __always_inline void fence_swapgs_kernel_entry(void) +{ + alternative("", "lfence", X86_FEATURE_FENCE_SWAPGS_KERNEL); +} + +static __always_inline void user_entry_swapgs_and_fence(void) +{ + native_swapgs(); + fence_swapgs_user_entry(); +} -- 2.19.1.6.gb485710b