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 X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80684C43461 for ; Wed, 12 May 2021 20:12:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 503CC6143F for ; Wed, 12 May 2021 20:12:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1384689AbhELUCL (ORCPT ); Wed, 12 May 2021 16:02:11 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:53288 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354186AbhELSfs (ORCPT ); Wed, 12 May 2021 14:35:48 -0400 From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1620844479; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KdNcJ8cEaSMgpbsP8tBqYM0z6corc8i7Q+IqLVoaSeI=; b=3x+cKd8kaBdN5LgKQSfI6isMBwiqQpyrzQri1RDEePZqtFMQda1NU3AzNJ5QQHoV0c4FQ8 /jw6Vrjp4LDjimTKLPcjzjH1XRq9qqmaEiE1dbge+Qe0x3DRV/HSGE8R++Bk+zWTGskdEF hxmHa9XeUAahJFqheh1+1S0A/D1RGuPA3V3c+35FpjLi/EfLHWNVNcTJCNl4zFti7EkLZ/ D1QT6NZMy3K3cr/wb0fw6K5dSPHTi2b+wm3sjUYPxAmWTH/U/1thh/tr5MDZl272BryNjv FSdpgfpBSvohUxvJafYVSXmx0OpHG3Xyj/6eV+yq6456C6w6aclMVHtTROl7fA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1620844479; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=KdNcJ8cEaSMgpbsP8tBqYM0z6corc8i7Q+IqLVoaSeI=; b=q1pkZx2cjT1GVCWu62URddV0ZE8eU1Js6/RuUC9ttaZ8Jpm1689ri3E0prukrnU5xUoDZI WOxqEgX1qNXkxTAA== To: "H. Peter Anvin" , Ingo Molnar , Borislav Petkov , Andy Lutomirski Cc: Linux Kernel Mailing List Subject: Re: [RFC v2 PATCH 7/7] x86/entry: use int for syscall number; handle all invalid syscall nrs In-Reply-To: <60495dd3-ea68-4db3-47ad-b7b45796bf76@zytor.com> References: <871racf928.ffs@nanos.tec.linutronix.de> <60495dd3-ea68-4db3-47ad-b7b45796bf76@zytor.com> Date: Wed, 12 May 2021 20:34:39 +0200 Message-ID: <87o8dfer7k.ffs@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 12 2021 at 11:21, H. Peter Anvin wrote: > On 5/12/21 5:09 AM, Thomas Gleixner wrote: >> >>> index 1d9db15fdc69..85f04ea0e368 100644 >>> --- a/arch/x86/entry/entry_64.S >>> +++ b/arch/x86/entry/entry_64.S >>> @@ -108,7 +108,7 @@ SYM_INNER_LABEL(entry_SYSCALL_64_after_hwframe, SYM_L_GLOBAL) >>> >>> /* IRQs are off. */ >>> movq %rsp, %rdi >>> - movq %rax, %rsi >>> + movslq %eax, %rsi >> >> This is wrong. >> >> syscall(long number,...); >> >> So the above turns syscall(UINT_MAX + N, ...) into syscall(N, ...). >> > > That is intentional, as (again) system calls are int. They are 'int' kernel internally, but _NOT_ at the user space visible side. Again: man syscall syscall(long number,...); So that results in a user ABI change. > As stated in my reply to Ingo, I'll clean the various descriptions and > try to capture the discussion better. If we agree to go there then this wants to be a seperate commit which does nothing else than changing this behaviour. Thanks, tglx