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 C034EC433FE for ; Fri, 26 Nov 2021 10:26:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377074AbhKZK34 (ORCPT ); Fri, 26 Nov 2021 05:29:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1376925AbhKZK1W (ORCPT ); Fri, 26 Nov 2021 05:27:22 -0500 Received: from mail-pf1-x42a.google.com (mail-pf1-x42a.google.com [IPv6:2607:f8b0:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 45C7CC061373 for ; Fri, 26 Nov 2021 02:15:40 -0800 (PST) Received: by mail-pf1-x42a.google.com with SMTP id g19so8469509pfb.8 for ; Fri, 26 Nov 2021 02:15:40 -0800 (PST) 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=sq0pyNwSiU0YOEEmJg4qMUcF5UCPsJUuDI8P3f7GAd0=; b=HP8PtrOxd5rcXiGux1HAhMocWpLMg/uReEzcxkOeuHPm+XHitXBcR4vrTlnf4GS+cH gmM/ZwJ3ykGB6OUqmU2VXqs+tQ+qm68vzpo1AAZztCo3cbNAu3ZDve6o9eNx0qfSkVxJ oe2EoW5qdqf6kg7vluVLtl+xFeiAEfEDmHqKqeEuiY5fG17H6itHtEisl9qUlUJ9IBun SpH9PpUqllAio7mF12FLAK9g9P9YaHIrk+4F1AkGe409fABH9AIAeni+8IeQJNZ1A7sy fc0k3jb0frrolS4CV7buWj26iMCy28DhmE1/N+JIiN3Ud95bHl47iQGWnGNP7Tl/o2Fr khJw== 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=sq0pyNwSiU0YOEEmJg4qMUcF5UCPsJUuDI8P3f7GAd0=; b=K87oc21pKjfdTzplAvA+m1FKacNFBr+11rFYFDWBqOFG044OxQBsQqP/LjdiNSJuWq 15sO2eDeiAVXbUqCEtqM6JLeJGD4DKyD8oKRqF7N5soi/jxgh+chuT5aClE4H9P1CBBI 79EHYDeJ/XTcJVOXJj1IH9ZuXdUluSzv4ncT4BM4kii7sAKoIPmOftIh/HSCXsQo5rwL HQYliRsvTivtLA9Nnx3oNs23gbWdn7Cq5UVvvkXHDCClVc2kV5Z8r/O7zs0N9XYPjpGl y4t7AcV28WZoik7zkcwb5NFxRjhM2zx17yFijAbsuTpN4XnJla2BQ0gn1weJVu6dkMuA o8jQ== X-Gm-Message-State: AOAM533VdtJcisHkSyKUxrOLF9yeLEGMTh/M1Nom1NaIX3qUqmRmQbGl FDOOE8tSPU/pUXrs0wNYvxa56dyXM8c= X-Google-Smtp-Source: ABdhPJx0vpvU0uf/5rcqKAlZf4+n6IwkDj0eCYQQffeWwROAxewl5qyfsOQvqkCBXHHHbR1aHDYvZg== X-Received: by 2002:a63:8449:: with SMTP id k70mr20245897pgd.27.1637921739661; Fri, 26 Nov 2021 02:15:39 -0800 (PST) Received: from localhost ([47.251.3.230]) by smtp.gmail.com with ESMTPSA id j127sm6436292pfg.14.2021.11.26.02.15.38 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Nov 2021 02:15:39 -0800 (PST) From: Lai Jiangshan To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Lai Jiangshan , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Juergen Gross , "Peter Zijlstra (Intel)" , Joerg Roedel Subject: [PATCH V6 36/49] x86/entry: Implement the C version ist_paranoid_exit() Date: Fri, 26 Nov 2021 18:11:56 +0800 Message-Id: <20211126101209.8613-37-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20211126101209.8613-1-jiangshanlai@gmail.com> References: <20211126101209.8613-1-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 It implements the whole ASM version paranoid_exit(). No functional difference intended. Signed-off-by: Lai Jiangshan --- arch/x86/entry/entry64.c | 41 +++++++++++++++++++++++++++++++++ arch/x86/include/asm/idtentry.h | 2 ++ 2 files changed, 43 insertions(+) diff --git a/arch/x86/entry/entry64.c b/arch/x86/entry/entry64.c index dc0bd9dc6d48..63a6021a1f70 100644 --- a/arch/x86/entry/entry64.c +++ b/arch/x86/entry/entry64.c @@ -269,6 +269,29 @@ static __always_inline unsigned long ist_switch_to_kernel_gsbase(void) return ret; } +static __always_inline void ist_restore_gsbase(unsigned long gsbase) +{ + /* + * Handle the three GSBASE cases. + * + * @gsbase contains the GSBASE related information depending + * on the availability of the FSGSBASE instructions: + * + * FSGSBASE @gsbase + * N 0 -> SWAPGS on exit + * 1 -> no SWAPGS on exit + * + * Y User space GSBASE, must be restored unconditionally + */ + if (static_cpu_has(X86_FEATURE_FSGSBASE)) { + wrgsbase(gsbase); + return; + } + + if (!gsbase) + native_swapgs(); +} + /* * Switch and save CR3 in *@cr3 if PTI enabled. Return GSBASE related * information in *@gsbase depending on the availability of the FSGSBASE @@ -305,3 +328,21 @@ void ist_paranoid_entry(unsigned long *cr3, unsigned long *gsbase) /* Handle GSBASE, store the return value in *@gsbase for exit. */ *gsbase = ist_switch_to_kernel_gsbase(); } + +/* + * "Paranoid" exit path from exception stack. This is invoked + * only on return from IST interrupts that came from kernel space. + * + * We may be returning to very strange contexts (e.g. very early + * in syscall entry), so checking for preemption here would + * be complicated. Fortunately, there's no good reason to try + * to handle preemption here. + */ +__visible __entry_text +void ist_paranoid_exit(unsigned long cr3, unsigned long gsbase) +{ + /* Restore CR3 at first, it can use kernel GSBASE. */ + ist_restore_cr3(cr3); + barrier(); + ist_restore_gsbase(gsbase); +} diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index f6efa21ec242..cf41901227ed 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -309,6 +309,8 @@ static __always_inline void __##func(struct pt_regs *regs) #ifdef CONFIG_X86_64 __visible __entry_text void ist_paranoid_entry(unsigned long *cr3, unsigned long *gsbase); +__visible __entry_text +void ist_paranoid_exit(unsigned long cr3, unsigned long gsbase); /** * DECLARE_IDTENTRY_IST - Declare functions for IST handling IDT entry points -- 2.19.1.6.gb485710b