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 188A5C433F5 for ; Tue, 3 May 2022 19:01:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241721AbiECTFA (ORCPT ); Tue, 3 May 2022 15:05:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241510AbiECTEn (ORCPT ); Tue, 3 May 2022 15:04:43 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5F6722B269; Tue, 3 May 2022 12:01:09 -0700 (PDT) Date: Tue, 03 May 2022 19:01:06 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1651604467; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZfbsK3DEwofUyZP10SDohoj0R8YYZ9/UiaSs68zJg/M=; b=CpNdu6qRgsPFlatg/oTxj5KfHGBoyXQo0gIQSSN+syg7IBtDErY0rk0K9pDoo4RRX5DprV xWapHyoOjkN8TsQ3iWY2/gvlxCM8U5+PD69tZfkAvZW2uHjQLvuQCHKcQKDXaD61T17wEA 00YiDm5dlbH28KvS7Kq8fKcS7FXK49XSp8JK/kch5OxwoT/Asub7aN56OWqWGSDx8e+1pB Tuu6xVn7IqqMCyCxKe8rxkp728wv21L5RcgvSeLxTDZV3EMNKbtafe/xO5p43+omvikIeR /4Ndt1mh9qCPDpx3fTRqtrvhpyWuB2rUkuFVbYkt8PiaumM71KnqRBXoR6JWhw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1651604467; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZfbsK3DEwofUyZP10SDohoj0R8YYZ9/UiaSs68zJg/M=; b=EJgSDBsW39CxBVnrMnqxs6GNhtkQ0cYP1xQvwYV9UEryXXvHwiWeioQVFPk6ExQvkT4vl5 lw/IJvjsqMZZ9aAQ== From: "tip-bot2 for Lai Jiangshan" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/asm] x86/entry: Switch the stack after error_entry() returns Cc: Lai Jiangshan , Borislav Petkov , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20220503032107.680190-3-jiangshanlai@gmail.com> References: <20220503032107.680190-3-jiangshanlai@gmail.com> MIME-Version: 1.0 Message-ID: <165160446663.4207.12038427447242778092.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/asm branch of tip: Commit-ID: 520a7e80c96d655fbe4650d9cc985bd9d0443389 Gitweb: https://git.kernel.org/tip/520a7e80c96d655fbe4650d9cc985bd9d0443389 Author: Lai Jiangshan AuthorDate: Thu, 21 Apr 2022 22:10:49 +08:00 Committer: Borislav Petkov CommitterDate: Tue, 03 May 2022 11:35:34 +02:00 x86/entry: Switch the stack after error_entry() returns error_entry() calls fixup_bad_iret() before sync_regs() if it is a fault from a bad IRET, to copy pt_regs to the kernel stack. It switches to the kernel stack directly after sync_regs(). But error_entry() itself is also a function call, so it has to stash the address it is going to return to, in %r12 which is unnecessarily complicated. Move the stack switching after error_entry() and get rid of the need to handle the return address. [ bp: Massage commit message. ] Signed-off-by: Lai Jiangshan Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220503032107.680190-3-jiangshanlai@gmail.com --- 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 ecbfca3..ca3e99e 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -326,6 +326,8 @@ SYM_CODE_END(ret_from_fork) .macro idtentry_body cfunc has_error_code:req call error_entry + movq %rax, %rsp /* switch to the task stack if from userspace */ + ENCODE_FRAME_POINTER UNWIND_HINT_REGS movq %rsp, %rdi /* pt_regs pointer into 1st argument*/ @@ -1002,14 +1004,10 @@ 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 /* @@ -1041,6 +1039,7 @@ 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: @@ -1061,12 +1060,9 @@ 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)