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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 542D9C433EF for ; Fri, 3 Dec 2021 14:12:38 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.237701.412284 (Exim 4.92) (envelope-from ) id 1mt9IX-0002RN-4I; Fri, 03 Dec 2021 14:12:25 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 237701.412284; Fri, 03 Dec 2021 14:12:25 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mt9IX-0002RG-1F; Fri, 03 Dec 2021 14:12:25 +0000 Received: by outflank-mailman (input) for mailman id 237701; Fri, 03 Dec 2021 14:12:23 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mt9IV-0002R0-DC for xen-devel@lists.xenproject.org; Fri, 03 Dec 2021 14:12:23 +0000 Received: from ppsw-32.csi.cam.ac.uk (ppsw-32.csi.cam.ac.uk [131.111.8.132]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 0827c63e-5443-11ec-b1df-f38ee3fbfdf7; Fri, 03 Dec 2021 15:12:22 +0100 (CET) Received: from hades.srcf.societies.cam.ac.uk ([131.111.179.67]:44318) by ppsw-32.csi.cam.ac.uk (ppsw.cam.ac.uk [131.111.8.136]:25) with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) id 1mt9IT-000mMJ-1s (Exim 4.95) (return-path ); Fri, 03 Dec 2021 14:12:21 +0000 Received: from [192.168.1.10] (host-92-12-61-86.as13285.net [92.12.61.86]) (Authenticated sender: amc96) by hades.srcf.societies.cam.ac.uk (Postfix) with ESMTPSA id 662331FC8B; Fri, 3 Dec 2021 14:12:21 +0000 (GMT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 0827c63e-5443-11ec-b1df-f38ee3fbfdf7 X-Cam-AntiVirus: no malware found X-Cam-ScannerInfo: https://help.uis.cam.ac.uk/email-scanner-virus Message-ID: <76c98cae-13d5-4ad8-9238-71bef56609d1@srcf.net> Date: Fri, 3 Dec 2021 14:12:21 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.2 Subject: Re: [PATCH 62/65] x86/entry: Make IDT entrypoints CET-IBT compatible Content-Language: en-GB To: Jan Beulich , Andrew Cooper Cc: =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , Xen-devel References: <20211126123446.32324-1-andrew.cooper3@citrix.com> <20211126123446.32324-63-andrew.cooper3@citrix.com> From: Andrew Cooper In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 03/12/2021 13:23, Jan Beulich wrote: > On 26.11.2021 13:34, Andrew Cooper wrote: >> Each IDT vector needs to land on an endbr64 instruction. This is especially >> important for the #CP handler, which will escalate to #DF if the endbr64 is >> missing. >> >> Signed-off-by: Andrew Cooper > Reviewed-by: Jan Beulich Thanks. > > One remark though: > >> @@ -1136,7 +1158,8 @@ autogen_stubs: /* Automatically generated stubs. */ >> #endif >> >> ALIGN >> -1: pushq $0 >> +1: ENDBR64 >> + pushq $0 >> movb $vec,4(%rsp) >> jmp common_interrupt >> >> @@ -1146,7 +1169,8 @@ autogen_stubs: /* Automatically generated stubs. */ >> .elseif vec == X86_EXC_CSO || vec == X86_EXC_SPV || \ >> vec == X86_EXC_VE || (vec > X86_EXC_CP && vec < TRAP_nr) >> >> -1: test $8,%spl /* 64bit exception frames are 16 byte aligned, but the word */ >> +1: ENDBR64 >> + test $8,%spl /* 64bit exception frames are 16 byte aligned, but the word */ >> jz 2f /* size is 8 bytes. Check whether the processor gave us an */ >> pushq $0 /* error code, and insert an empty one if not. */ >> 2: movb $vec,4(%rsp) > Like with initializers of compound objects vs trailing commas there, I > think it would help if we moved away from placing insns on the same > lines as labels. As can be seen here, inserting something always means > touching two lines instead of just adding one. I had actually wondered the same, without drawing a comparison to trailing commas.  I'll adjust. ~Andrew