Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753093AbeAJBYk (ORCPT + 1 other); Tue, 9 Jan 2018 20:24:40 -0500 Received: from mail-pg0-f66.google.com ([74.125.83.66]:35195 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751252AbeAJBYj (ORCPT ); Tue, 9 Jan 2018 20:24:39 -0500 X-Google-Smtp-Source: ACJfBostIxOmeuW+ucdv3tGt/V4r2WcmoLGtM+A1qH9jFHGLsqZxUqjuyYp186opCsS2nXbB8YWZnA== Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (1.0) Subject: Re: [PATCH v1 8/8] x86/entry/clearregs: Clear registers for 32bit kernel From: Andy Lutomirski X-Mailer: iPhone Mail (15C153) In-Reply-To: <20180110010328.22163-9-andi@firstfloor.org> Date: Tue, 9 Jan 2018 17:24:36 -0800 Cc: tglx@linutronix.de, x86@kernel.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, dwmw@amazon.co.uk, pjt@google.com, luto@kernel.org, peterz@infradead.org, thomas.lendacky@amd.com, tim.c.chen@linux.intel.com, gregkh@linux-foundation.org, dave.hansen@intel.com, jikos@kernel.org, Andi Kleen Content-Transfer-Encoding: 8BIT Message-Id: <2C51FBC8-EB93-4003-9EB5-E3F94B1E05FA@amacapital.net> References: <20180110010328.22163-1-andi@firstfloor.org> <20180110010328.22163-9-andi@firstfloor.org> To: Andi Kleen Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: > On Jan 9, 2018, at 5:03 PM, Andi Kleen wrote: > > From: Andi Kleen > > On a 32bit kernel clearing registers is much simpler than > on 64bit. The arguments for syscalls are initially passed > to a C function through the stack, so there's no need > to figure out how many arguments to clear. Why are we even trying to improve the situation on 32-bit? Unless someone actually tries to implement PTI, this seems useless.