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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FB97C433F5 for ; Wed, 10 Nov 2021 11:59:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E304061152 for ; Wed, 10 Nov 2021 11:59:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231750AbhKJMCZ (ORCPT ); Wed, 10 Nov 2021 07:02:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35656 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231747AbhKJMCR (ORCPT ); Wed, 10 Nov 2021 07:02:17 -0500 Received: from mail-pl1-x62a.google.com (mail-pl1-x62a.google.com [IPv6:2607:f8b0:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F1F5BC061766 for ; Wed, 10 Nov 2021 03:59:29 -0800 (PST) Received: by mail-pl1-x62a.google.com with SMTP id b13so2846807plg.2 for ; Wed, 10 Nov 2021 03:59:29 -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=nHCZGxKN3KBd+O5Qi5dSjkEt/UOdmetDDo4XYyeRAyE=; b=oTmlxHs301RiGUq40HNvjcPCMfokdFkV1ZkxuIz0KKkFzhbHikk6SEflwB4DzhCmra 57eckNUYeEOtrrMDB0TsAJ400vPEacLDbvcW0LlfAuJaqXs6x8+LVEjS3qiyu7SQTtgc LVKuvdxjPoDxfBY7jedawdvf9odwwbebv2zapBsWr+KwRIX0lCVPUhAUeLdfzpCYfOTN 01XNtN9I6M67LbGb61f/tJq2T9UVvtgmxz8Av9AIY8yQNHXQBrTJ+/J9qPUsZko3xjU3 bbaOzsKN/nvOT9UPA5GvixAu8JJxfS2a3ex9Pbogl69jG5eiMPtGk0KsdsUYE392N7Ab 17YQ== 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=nHCZGxKN3KBd+O5Qi5dSjkEt/UOdmetDDo4XYyeRAyE=; b=dEphLI8Jz/VP8jPad9QeRTdvaUulC3AUXoAL30R77+z6+PLLDHiOK5XhZhDc9t0GoL /RqniK/O58JohI9L22xW6aobZ2t0BWw/dvOfAbKe5R0GzhJ4rt2U9PqMw53P1iSsnSlA 1bq4GDhMRxmIfrCibFqGsw0y5v/WA3w7OUvwwHiTfW7pE7aN8kkCrrSJ/Wn+5o6FjaNN +yK9uTAChWL+Ypg4ZcTbtJL+tYJlNqcWXyOjE5+QA/d5FP30khCDH6gQf8yXTV9ii/sS uXx7gRoDYTezF3geBUcSc1TXHssQ9Om8/2NKYr4jrinxcgtIGHq8Kp74rkciO6JLTNa9 +Niw== X-Gm-Message-State: AOAM532l9nkuNKxkwOgHbTyNl09jKZ09diBIMzRezAHYn4092E5gbZEn hFtJEAOWb6xe/C3NPO40mbStZplZqyw= X-Google-Smtp-Source: ABdhPJzgAMuzfykWS9OYcDggvoEflmiOxE/enn1amyNfftBLC6h7bNOhkfLYnA7ceoFBFHaOr2PwaA== X-Received: by 2002:a17:902:c202:b0:142:2441:aa25 with SMTP id 2-20020a170902c20200b001422441aa25mr15186198pll.68.1636545569209; Wed, 10 Nov 2021 03:59:29 -0800 (PST) Received: from localhost ([198.11.178.15]) by smtp.gmail.com with ESMTPSA id q11sm16583249pfk.192.2021.11.10.03.59.28 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 10 Nov 2021 03:59:28 -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" Subject: [PATCH V5 19/50] x86/entry: Switch the stack after error_entry() returns Date: Wed, 10 Nov 2021 19:57:05 +0800 Message-Id: <20211110115736.3776-20-jiangshanlai@gmail.com> X-Mailer: git-send-email 2.19.1.6.gb485710b In-Reply-To: <20211110115736.3776-1-jiangshanlai@gmail.com> References: <20211110115736.3776-1-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 error_entry() calls sync_regs() to settle/copy the pt_regs and switches the stack directly after sync_regs(). But because error_entry() is also called from entry, the switching has to handle the return address together, which causes the behavior tangly. Switching to the stack after error_entry() makes the code simpler and intuitive. Signed-off-by: Lai Jiangshan --- arch/x86/entry/entry_64.S | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index c6b617c19fe1..3667317f6825 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -323,6 +323,8 @@ SYM_CODE_END(ret_from_fork) .macro idtentry_body cfunc has_error_code:req call error_entry + movq %rax, %rsp /* switch stack settled by sync_regs() */ + ENCODE_FRAME_POINTER UNWIND_HINT_REGS movq %rsp, %rdi /* pt_regs pointer into 1st argument*/ @@ -988,14 +990,10 @@ SYM_CODE_START_LOCAL(error_entry) /* We have user CR3. Change to kernel CR3. */ SWITCH_TO_KERNEL_CR3 scratch_reg=%rax + leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */ .Lerror_entry_from_usermode_after_swapgs: /* Put us onto the real thread stack. */ - popq %r12 /* save return addr in %12 */ - movq %rsp, %rdi /* arg0 = pt_regs pointer */ call sync_regs - movq %rax, %rsp /* switch stack */ - ENCODE_FRAME_POINTER - pushq %r12 ret /* @@ -1028,6 +1026,7 @@ SYM_CODE_START_LOCAL(error_entry) */ .Lerror_entry_done_lfence: FENCE_SWAPGS_KERNEL_ENTRY + leaq 8(%rsp), %rax /* return pt_regs pointer */ ret .Lbstep_iret: @@ -1048,12 +1047,9 @@ SYM_CODE_START_LOCAL(error_entry) * Pretend that the exception came from user mode: set up pt_regs * as if we faulted immediately after IRET. */ - popq %r12 /* save return addr in %12 */ - movq %rsp, %rdi /* arg0 = pt_regs pointer */ + leaq 8(%rsp), %rdi /* arg0 = pt_regs pointer */ call fixup_bad_iret - mov %rax, %rsp - ENCODE_FRAME_POINTER - pushq %r12 + mov %rax, %rdi jmp .Lerror_entry_from_usermode_after_swapgs SYM_CODE_END(error_entry) -- 2.19.1.6.gb485710b